Evacuated displacement compression molding

NASA Technical Reports Server (NTRS)

Heier, W. C. (Inventor)

1973-01-01

A process for molding long, thin-wall tubular bodies from thermosetting plastic molding compounds is described. The tubular bodies produced may have body lengths several times the diameters. The application of the process for manufacturing rocket engine cases and nozzles is discussed. The advantages of the system over other methods of circular tube manufacture are analyzed.

Investigation of compression behavior of PE/EVA foam injection molded parts

NASA Astrophysics Data System (ADS)

Spina, Roberto

2017-10-01

The main objective of the presented work is to evaluate the compression behavior of a polymeric foam blend by using a robust framework for the testing sequence of foaming injection molded parts, with the aim of establishing a standard testing cycle for the evaluation of new matrix material. The research purpose is to assess parameters influencing compression behavior and give useful suggestions for the implementation of a finite element analysis. The polymeric blend consisted of a mixture of low density polyethylenes (LDPEs), a high-density polyethylene (HDPE), an ethylene-vinyl acetate (EVA) and an azodicarbonamide (ADC). The thermal, rheological and compression properties of the blend are fully described, as well as the injection molding process for two specimen types.

Direct molding of pavement tiles made of ground tire rubber

NASA Astrophysics Data System (ADS)

Quadrini, Fabrizio; Gagliardi, Donatella; Tedde, Giovanni Matteo; Santo, Loredana; Musacchi, Ettore

2016-10-01

Large rubber products can be molded by using only ground tire rubber (GTR) without any additive or binder due to a new technology called "direct molding". Rubber granules and powders from tire recycling are compression molded at elevated temperatures and pressures. The feasibility of this process was clearly shown in laboratory but the step to the industrial scale was missing. Thanks to an European Project (SMART "Sustainable Molding of Articles from Recycled Tires") this step has been made and some results are reported in this study. The press used for compression molding is described. Some tests were made to measure the energy consumption so as to evaluate costs for production in comparison with conventional technologies for GTR molding (by using binders). Results show that 1 m2 tiles can be easily molded with several thicknesses in a reasonable low time. Energy consumption is higher than conventional technologies but it is lower than the cost for binders.

Staged mold for encapsulating hazardous wastes

DOEpatents

Unger, Samuel L.; Telles, Rodney W.; Lubowitz, Hyman R.

1990-01-01

A staged mold for stabilizing hazardous wastes for final disposal by molding an agglomerate of the hazardous wastes and encapsulating the agglomerate. Three stages are employed in the process. In the first stage, a first mold body is positioned on a first mold base, a mixture of the hazardous wastes and a thermosetting plastic is loaded into the mold, the mixture is mechanically compressed, heat is applied to cure the mixture to form a rigid agglomerate, and the first mold body is removed leaving the agglomerate sitting on the first mold base. In the second stage, a clamshell second mold body is positioned around the agglomerate and the first mold base, a powdered thermoplastic resin is poured on top of the agglomerate and in the gap between the sides of the agglomerate and the second mold body, the thermoplastic is compressed, heat is applied to melt the thermoplastic, and the plastic is cooled jacketing the agglomerate on the top and sides. In the third stage, the mold with the jacketed agglomerate is inverted, the first mold base is removed exposing the former bottom of the agglomerate, powdered thermoplastic is poured over the former bottom, the first mold base is replaced to compress the thermoplastic, heat is applied to melt the new thermoplastic and the top part of the jacket on the sides, the plastic is cooled jacketing the bottom and fusing with the jacketing on the sides to complete the seamless encapsulation of the agglomerate.

Staged mold for encapsulating hazardous wastes

DOEpatents

Unger, Samuel L.; Telles, Rodney W.; Lubowitz, Hyman R.

1988-01-01

A staged mold for stabilizing hazardous wastes for final disposal by molding an agglomerate of the hazardous wastes and encapsulating the agglomerate. Three stages are employed in the process. In the first stage, a first mold body is positioned on a first mold base, a mixture of the hazardous wastes and a thermosetting plastic is loaded into the mold, the mixture is mechanically compressed, heat is applied to cure the mixture to form a rigid agglomerate, and the first mold body is removed leaving the agglomerate sitting on the first mold base. In the second stage, a clamshell second mold body is positioned around the agglomerate and the first mold base, a powdered thermoplastic resin is poured on top of the agglomerate and in the gap between the sides of the agglomerate and the second mold body, the thermoplastic is compressed, heat is applied to melt the thermoplastic, and the plastic is cooled jacketing the agglomerate on the top and sides. In the third stage, the mold with the jacketed agglomerate is inverted, the first mold base is removed exposing the former bottom of the agglomerate, powdered thermoplastic is poured over the former bottom, the first mold base is replaced to compress the thermoplastic, heat is applied to melt the new thermoplastic and the top part of the jacket on the sides, the plastic is cooled jacketing the bottom and fusing with the jacketing on the sides to complete the seamless encapsulation of the agglomerate.

Method for encapsulating hazardous wastes using a staged mold

DOEpatents

Unger, Samuel L.; Telles, Rodney W.; Lubowitz, Hyman R.

1989-01-01

A staged mold and method for stabilizing hazardous wastes for final disposal by molding an agglomerate of the hazardous wastes and encapsulating the agglomerate. Three stages are employed in the process. In the first stage, a first mold body is positioned on a first mold base, a mixture of the hazardous wastes and a thermosetting plastic is loaded into the mold, the mixture is mechanically compressed, heat is applied to cure the mixture to form a rigid agglomerate, and the first mold body is removed leaving the agglomerate sitting on the first mold base. In the second stage, a clamshell second mold body is positioned around the agglomerate and the first mold base, a powdered thermoplastic resin is poured on top of the agglomerate and in the gap between the sides of the agglomerate and the second mold body, the thermoplastic is compressed, heat is applied to melt the thermoplastic, and the plastic is cooled jacketing the agglomerate on the top and sides. In the third stage, the mold with the jacketed agglomerate is inverted, the first mold base is removed exposing the former bottom of the agglomerate, powdered thermoplastic is poured over the former bottom, the first mold base is replaced to compress the thermoplastic, heat is applied to melt the new thermoplastic and the top part of the jacket on the sides, the plastic is cooled jacketing the bottom and fusing with the jacketing on the sides to complete the seamless encapsulation of the agglomerate.

Natural Fiber Composite Retting, Preform Manufacture and Molding (Project 18988/Agreement 16313)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Simmons, Kevin L.; Howe, Daniel T.; Laddha, Sachin

2009-12-31

Plant-based natural fibers can be used in place of glass in fiber reinforced automotive composites to reduce weight, cost and provide environmental benefits. Current automotive applications use natural fibers in injection molded thermoplastics for interior, non-structural applications. Compression molded natural fiber reinforced thermosets have the opportunity to extend natural fiber composite applications to structural and semi-structural parts and exterior parts realizing further vehicle weight savings. The development of low cost molding and fiber processing techniques for large volumes of natural fibers has helped in understanding the barriers of non-aqueous retting. The retting process has a significant effect on the fibermore » quality and its processing ability that is related to the natural fiber composite mechanical properties. PNNL has developed a compression molded fiber reinforced composite system of which is the basis for future preforming activities and fiber treatment. We are using this process to develop preforming techniques and to validate fiber treatment methods relative to OEM provided application specifications. It is anticipated for next fiscal year that demonstration of larger quantities of SMC materials and molding of larger, more complex components with a more complete testing regimen in coordination with Tier suppliers under OEM guidance.« less

Brightness field distributions of microlens arrays using micro molding.

PubMed

Cheng, Hsin-Chung; Huang, Chiung-Fang; Lin, Yi; Shen, Yung-Kang

2010-12-20

This study describes the brightness field distributions of microlens arrays fabricated by micro injection molding (μIM) and micro injection-compression molding (μICM). The process for fabricating microlens arrays used room-temperature imprint lithography, photoresist reflow, electroforming, μIM, μICM, and optical properties measurement. Analytical results indicate that the brightness field distribution of the molded microlens arrays generated by μICM is better than those made using μIM. Our results further demonstrate that mold temperature is the most important processing parameter for brightness field distribution of molded microlens arrays made by μIM or μICM.

40 CFR Table 9 to Subpart Wwww of... - Initial Compliance With Work Practice Standards

Code of Federal Regulations, 2014 CFR

2014-07-01

... compression/injection molding uncover, unwrap or expose only one charge per mold cycle per compression/injection molding machine. For machines with multiple molds, one charge means sufficient material to fill... cycle per compression/injection molding machine, or prior to the loader, hoppers are closed except when...

Method for compression molding of thermosetting plastics utilizing a temperature gradient across the plastic to cure the article

NASA Technical Reports Server (NTRS)

Heier, W. C. (Inventor)

1974-01-01

A method is described for compression molding of thermosetting plastics composition. Heat is applied to the compressed load in a mold cavity and adjusted to hold molding temperature at the interface of the cavity surface and the compressed compound to produce a thermal front. This thermal front advances into the evacuated compound at mean right angles to the compression load and toward a thermal fence formed at the opposite surface of the compressed compound.

Manufacturing Process Selection of Composite Bicycle’s Crank Arm using Analytical Hierarchy Process (AHP)

NASA Astrophysics Data System (ADS)

Luqman, M.; Rosli, M. U.; Khor, C. Y.; Zambree, Shayfull; Jahidi, H.

2018-03-01

Crank arm is one of the important parts in a bicycle that is an expensive product due to the high cost of material and production process. This research is aimed to investigate the potential type of manufacturing process to fabricate composite bicycle crank arm and to describe an approach based on analytical hierarchy process (AHP) that assists decision makers or manufacturing engineers in determining the most suitable process to be employed in manufacturing of composite bicycle crank arm at the early stage of the product development process to reduce the production cost. There are four types of processes were considered, namely resin transfer molding (RTM), compression molding (CM), vacuum bag molding and filament winding (FW). The analysis ranks these four types of process for its suitability in the manufacturing of bicycle crank arm based on five main selection factors and 10 sub factors. Determining the right manufacturing process was performed based on AHP process steps. Consistency test was performed to make sure the judgements are consistent during the comparison. The results indicated that the compression molding was the most appropriate manufacturing process because it has the highest value (33.6%) among the other manufacturing processes.

Microcellular injection molding process for producing lightweight thermoplastic polyurethane with customizable properties

NASA Astrophysics Data System (ADS)

Ellingham, Thomas; Kharbas, Hrishikesh; Manitiu, Mihai; Scholz, Guenter; Turng, Lih-Sheng

2018-03-01

A three-stage molding process involving microcellular injection molding with core retraction and an "out-of-mold" expansion was developed to manufacture thermoplastic polyurethane into lightweight foams of varying local densities, microstructures, and mechanical properties in the same microcellular injection molded part. Two stages of cavity expansion through sequential core retractions and a third expansion in a separate mold at an elevated temperature were carried out. The densities varied from 0.25 to 0.42 g/cm3 (77% to 62% weight reduction). The mechanical properties varied as well. Cyclic compressive strengths and hysteresis loss ratios, together with the microstructures, were characterized and reported.

Effect of processing method on the mechanical and thermal of Silvergrass/HDPE composites

NASA Astrophysics Data System (ADS)

Liu, Bing; Jin, Yueqiang; Wang, Shuying

2017-05-01

This paper investigates the effect of compression and injection molding methods on properties of Silvergrass-HDPE (High Density Polyethylene) composites, with respect to mechanical behaviors. Maleated polyethylene (MAPE) was added in the composite and improved the mechanical property of the composite. The research founds MAPE can improve the mechanical property because it improved the interfacial compatibility as a coupling agent. When added a content of 8% of MAPE, Silvergrass-HDPE composites made from compression molding shows a better mechanical performance in tensile strength and flexural strength than that made from injection molding, with increasing Silvergrass fiber content from 30% to 50%. However, the WPCs (wood plastics composites) made from injection molding had a lower degree of crystallinity with or without MAPE treatment.

Evacuated, displacement compression mold. [of tubular bodies from thermosetting plastics

NASA Technical Reports Server (NTRS)

Heier, W. C. (Inventor)

1974-01-01

A process of molding long thin-wall tubular bodies from thermosetting plastic molding compounds is described wherein the tubular body lengths may be several times the diameters. The process is accomplished by loading a predetermined quantity of molding compound into a female mold cavity closed at one end by a force mandrel. After closing the other end of the female mold with a balance mandrel, the loaded cavity is evacuated by applying a vacuum of from one-to-five mm pressure for a period of fifteen-to-thirty minutes. The mold temperature is raised to the minimum temperature at which the resin constituent of the compound will soften or plasticize and a pressure of 2500 psi is applied.

Comparison of Fit of Dentures Fabricated by Traditional Techniques Versus CAD/CAM Technology.

PubMed

McLaughlin, J Bryan; Ramos, Van; Dickinson, Douglas P

2017-11-14

To compare the shrinkage of denture bases fabricated by three methods: CAD/CAM, compression molding, and injection molding. The effect of arch form and palate depth was also tested. Nine titanium casts, representing combinations of tapered, ovoid, and square arch forms and shallow, medium, and deep palate depths, were fabricated using electron beam melting (EBM) technology. For each base fabrication method, three poly(vinyl siloxane) impressions were made from each cast, 27 dentures for each method. Compression-molded dentures were fabricated using Lucitone 199 poly methyl methacrylate (PMMA), and injection molded dentures with Ivobase's Hybrid Pink PMMA. For CAD/CAM, denture bases were designed and milled by Avadent using their Light PMMA. To quantify the space between the denture and the master cast, silicone duplicating material was placed in the intaglio of the dentures, the titanium master cast was seated under pressure, and the silicone was then trimmed and recovered. Three silicone measurements per denture were recorded, for a total of 243 measurements. Each silicone measurement was weighed and adjusted to the surface area of the respective arch, giving an average and standard deviation for each denture. Comparison of manufacturing methods showed a statistically significant difference (p = 0.0001). Using a ratio of the means, compression molding had on average 41% to 47% more space than injection molding and CAD/CAM. Comparison of arch/palate forms showed a statistically significant difference (p = 0.023), with shallow palate forms having more space with compression molding. The ovoid shallow form showed CAD/CAM and compression molding had more space than injection molding. Overall, injection molding and CAD/CAM fabrication methods produced equally well-fitting dentures, with both having a better fit than compression molding. Shallow palates appear to be more affected by shrinkage than medium or deep palates. Shallow ovoid arch forms appear to benefit from the use of injection molding compared to CAD/CAM and compression molding. © 2017 by the American College of Prosthodontists.

Fabrication of tunable diffraction grating by imprint lithography with photoresist mold

NASA Astrophysics Data System (ADS)

Yamada, Itsunari; Ikeda, Yusuke; Higuchi, Tetsuya

2018-05-01

We fabricated a deformable transmission silicone [poly(dimethylsiloxane)] grating using a two-beam interference method and imprint lithography and evaluated its optical characteristics during a compression process. The grating pattern with 0.43 μm depth and 1.0 μm pitch was created on a silicone surface by an imprinting process with a photoresist mold to realize a simple, low-cost fabrication process. The first-order diffraction transmittance of this grating reached 10.3% at 632.8 nm wavelength. We also measured the relationship between the grating period and compressive stress to the fabricated elements. The grating period changed from 1.0 μm to 0.84 μm by 16.6% compression of the fabricated element in one direction, perpendicular to the grooves, and the first-order diffraction transmittance was 8.6%.

Fabrication of an infrared Shack-Hartmann sensor by combining high-speed single-point diamond milling and precision compression molding processes.

PubMed

Zhang, Lin; Zhou, Wenchen; Naples, Neil J; Yi, Allen Y

2018-05-01

A novel fabrication method by combining high-speed single-point diamond milling and precision compression molding processes for fabrication of discontinuous freeform microlens arrays was proposed. Compared with slow tool servo diamond broaching, high-speed single-point diamond milling was selected for its flexibility in the fabrication of true 3D optical surfaces with discontinuous features. The advantage of single-point diamond milling is that the surface features can be constructed sequentially by spacing the axes of a virtual spindle at arbitrary positions based on the combination of rotational and translational motions of both the high-speed spindle and linear slides. By employing this method, each micro-lenslet was regarded as a microstructure cell by passing the axis of the virtual spindle through the vertex of each cell. An optimization arithmetic based on minimum-area fabrication was introduced to the machining process to further increase the machining efficiency. After the mold insert was machined, it was employed to replicate the microlens array onto chalcogenide glass. In the ensuing optical measurement, the self-built Shack-Hartmann wavefront sensor was proven to be accurate in detecting an infrared wavefront by both experiments and numerical simulation. The combined results showed that precision compression molding of chalcogenide glasses could be an economic and precision optical fabrication technology for high-volume production of infrared optics.

Transfer molding of PMR-15 polyimide resin

NASA Technical Reports Server (NTRS)

Reardon, J. P.; Moyer, D. W.; Nowak, B. E.

1985-01-01

Transfer molding is an economically viable method of producing small shapes of PMR-15 polyimide. It is shown that with regard to flexural, compressive, and tribological properties transfer-molded PMR-15 polyimide is essentially equivalent to PMR-15 polyimide produced by the more common method of compression molding. Minor variations in anisotropy are predictable effects of molding design and secondary finishing operations.

Deformable silicone grating fabricated with a photo-imprinted polymer mold

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yamada, Itsunari, E-mail: yamada.i@e.usp.ac.jp; Nishii, Junji; Saito, Mitsunori

A tunable transmission grating was fabricated by molding a silicone elastomer (polydimethylsiloxane). Its optical characteristics were then evaluated during compression. For fabrication, a glass plate with a photoimprinted polymer grating film was used as a mold. Both the grating period and diffraction transmittance of the molded elastomer were functions of the compressive stress. The grating period changed from 3.02 to 2.86 μm during compressing the elastomer in the direction perpendicular to the grooves.

Numerical-experimental investigation of PE/EVA foam injection molded parts

NASA Astrophysics Data System (ADS)

Spina, Roberto

The main objective of the presented work is to propose a robust framework to test foaming injection molded parts, with the aim of establishing a standard testing cycle for the evaluation of a new foam material based on numerical and experimental results. The research purpose is to assess parameters influencing several aspects, such as foam morphology and compression behavior, using useful suggestions from finite element analysis. The investigated polymeric blend consisted of a mixture of low density polyethylenes (LDPEs), a high-density polyethylene (HDPE), an ethylene-vinyl acetate (EVA) and an azodicarbonamide (ADC). The thermal, rheological and compression properties of the blend are fully described, as well as the numerical models and the parameters of the injection molding process.

Topographic design and application of hierarchical polymer surfaces replicated by microinjection compression molding

NASA Astrophysics Data System (ADS)

Guan, Wei-Sheng; Huang, Han-Xiong; Wang, Bin

2013-10-01

In recent years, the fast growing demand for biomimetic surfaces featuring unique wettability and functionality in various fields highlights the necessity of developing a reliable technique for mass production. In this work, hierarchical topography designs of templates were applied to prepare superhydrophobic surfaces via microinjection compression molding, comprehensively considering the feasibility of mechanical demolding and the superhydrophobicity and mechanical robustness of the molded polypropylene parts. Mimicking the wettability of a lotus leaf or rose petal, superhydrophobic surfaces were replicated. An unstable wetting state formed on the surface exhibiting the petal effect. On such a surface, the increased water pressure could cause water penetration into the micro gaps between the hierarchical asperities featuring low-roughness sidewalls and bottom surface; the resultant water membrane led to drastically increased water adhesion of the surface. Moreover, the low-adhesion superhydrophobicity of the molded surface was changed into superhydrophilicity, by means of introducing carbonyl groups via ultraviolet/ozone treatment and the subsequent water membrane preserved in microstructures via the pre-wetting process. Patterning the superhydrophilic micro channel on the superhydrophobic surface developed the surface microfluidic devices for micro-liter fluid pumping and mixing processes driven by surface tension.

Foam injection molding of thermoplastic elastomers: Blowing agents, foaming process and characterization of structural foams

NASA Astrophysics Data System (ADS)

Ries, S.; Spoerrer, A.; Altstaedt, V.

2014-05-01

Polymer foams play an important role caused by the steadily increasing demand to light weight design. In case of soft polymers, like thermoplastic elastomers (TPE), the haptic feeling of the surface is affected by the inner foam structure. Foam injection molding of TPEs leads to so called structural foam, consisting of two compact skin layers and a cellular core. The properties of soft structural foams like soft-touch, elastic and plastic behavior are affected by the resulting foam structure, e.g. thickness of the compact skins and the foam core or density. This inner structure can considerably be influenced by different processing parameters and the chosen blowing agent. This paper is focused on the selection and characterization of suitable blowing agents for foam injection molding of a TPE-blend. The aim was a high density reduction and a decent inner structure. Therefore DSC and TGA measurements were performed on different blowing agents to find out which one is appropriate for the used TPE. Moreover a new analyzing method for the description of processing characteristics by temperature dependent expansion measurements was developed. After choosing suitable blowing agents structural foams were molded with different types of blowing agents and combinations and with the breathing mold technology in order to get lower densities. The foam structure was analyzed to show the influence of the different blowing agents and combinations. Finally compression tests were performed to estimate the influence of the used blowing agent and the density reduction on the compression modulus.

Compression molding of aerogel microspheres

DOEpatents

Pekala, R.W.; Hrubesh, L.W.

1998-03-24

An aerogel composite material produced by compression molding of aerogel microspheres (powders) mixed together with a small percentage of polymer binder to form monolithic shapes in a cost-effective manner is disclosed. The aerogel composites are formed by mixing aerogel microspheres with a polymer binder, placing the mixture in a mold and heating under pressure, which results in a composite with a density of 50--800 kg/m{sup 3} (0.05--0.80 g/cc). The thermal conductivity of the thus formed aerogel composite is below that of air, but higher than the thermal conductivity of monolithic aerogels. The resulting aerogel composites are attractive for applications such as thermal insulation since fabrication thereof does not require large and expensive processing equipment. In addition to thermal insulation, the aerogel composites may be utilized for filtration, ICF target, double layer capacitors, and capacitive deionization. 4 figs.

Compression molding of aerogel microspheres

DOEpatents

Pekala, Richard W.; Hrubesh, Lawrence W.

1998-03-24

An aerogel composite material produced by compression molding of aerogel microspheres (powders) mixed together with a small percentage of polymer binder to form monolithic shapes in a cost-effective manner. The aerogel composites are formed by mixing aerogel microspheres with a polymer binder, placing the mixture in a mold and heating under pressure, which results in a composite with a density of 50-800 kg/m.sup.3 (0.05-0.80 g/cc). The thermal conductivity of the thus formed aerogel composite is below that of air, but higher than the thermal conductivity of monolithic aerogels. The resulting aerogel composites are attractive for applications such as thermal insulation since fabrication thereof does not require large and expensive processing equipment. In addition to thermal insulation, the aerogel composites may be utilized for filtration, ICF target, double layer capacitors, and capacitive deionization.

Compression molded energy storage flywheels

NASA Astrophysics Data System (ADS)

Burdick, P. A.

Materials choices, manufacturing processes, and benefits of flywheels as an effective energy storage device are discussed. Tests at the LL Laboratories have indicated that compressing molding of plies of structural sheet molding compound (SMC) filled with randomly oriented fibers produces a laminated disk with transversely isotropic properties. Good performance has been realized with a carbon/epoxy system, which displays satisfactory stiffness and strength in flywheel applications. A core profile has been selected, consisting of a uniform 1 in cross sectional thickness and a 21 in diam. Test configurations using three different resin paste formulations were compared after being mounted elastomerically on aluminum hubs. Further development was found necessary on accurate balancing and hub bonding. It was concluded that the SMC flywheels display the low-cost, sufficient energy densities, suitable dynamic stability characteristics, and acceptably benign failure modes for automotive applications.

Rapid localized heating of graphene coating on a silicon mold by induction for precision molding of polymer optics.

PubMed

Zhang, Lin; Zhou, Wenchen; Yi, Allen Y

2017-04-01

In compression molding of polymer optical components with micro/nanoscale surface features, rapid heating of the mold surface is critical for the implementation of this technology for large-scale applications. In this Letter, a novel method of a localized rapid heating process is reported. This process is based on induction heating of a thin conductive coating deposited on a silicon mold. Since the graphene coating is very thin (∼45  nm), a high heating rate of 10∼20°C/s can be achieved by employing a 1200 W 30 kHz electrical power unit. Under this condition, the graphene-coated surface and the polymer substrate can be heated above the polymer's glass transition temperature within 30 s and subsequently cooled down to room temperature within several tens of seconds after molding, resulting in an overall thermal cycle of about 3 min or shorter. The feasibility of this process was validated by fabrication of optical gratings, micropillar matrices, and microlens arrays on polymethylmethacrylate (PMMA) substrates with very high precision. The uniformity and surface geometries of the replicated optical elements are evaluated using an optical profilometer, a diffraction test setup, and a Shack-Hartmann wavefront sensor built with a molded PMMA microlens array. Compared with the conventional bulk heating molding process, this novel rapid localized induction heating process could improve replication efficiency with better geometrical fidelity.

The compression of wood/thermoplastic fiber mats during consolidation

Treesearch

Karl R. Englund; Michael P. Wolcott; John C. Hermanson

2004-01-01

Secondary processing of non-woven wood and wood/thermoplastic fiber mats is generally performed using compression molding, where heated platens or dies form the final product. Although the study and use of wood-fiber composites is widespread, few research efforts have explicitly described the fundamentals of mat consolidation. In contrast, the wood composite literature...

Mold Heating and Cooling Pump Package Operator Interface Controls Upgrade

DOE Office of Scientific and Technical Information (OSTI.GOV)

Josh A. Salmond

2009-08-07

The modernization of the Mold Heating and Cooling Pump Package Operator Interface (MHC PP OI) consisted of upgrading the antiquated single board computer with a proprietary operating system to off-the-shelf hardware and off-the-shelf software with customizable software options. The pump package is the machine interface between a central heating and cooling system that pumps heat transfer fluid through an injection or compression mold base on a local plastic molding machine. The operator interface provides the intelligent means of controlling this pumping process. Strict temperature control of a mold allows the production of high quality parts with tight tolerances and lowmore » residual stresses. The products fabricated are used on multiple programs.« less

Method for Selective Cleaning of Mold Release from Composite Honeycomb Surfaces

NASA Technical Reports Server (NTRS)

Pugel, Diane

2011-01-01

Honeycomb structures are commonly employed as load- and force-bearing structures as they are structurally strong and lightweight. Manufacturing processes for heat-molded composite honeycomb structures commence with the placement of pre-impregnated composite layups over metal mandrels. To prevent permanent bonding between the composite layup and the metal mandrels, an agent, known as a mold release agent, is used. Mold release agents allow the molded composite material to be removed from mandrels after a heat-forming process. Without a specific removal process, mold release agents may continue to adhere to the surface of the composite material, thereby affecting the bonding of other materials that may come into contact with the composite surface in later stages of processing A constituent common to commercially available household cleaning agents is employed for the removal of mold release agents common to the manufacturing of heat-formed composite materials. The reliability of the solvent has been proven by the longevity and reliability of commercial household cleaners. At the time of this reporting, no one has attempted using constituent for this purpose. The material to be cleaned is immersed in the solution, vertically removed so that the solution is allowed to drain along cell walls and into a solvent bath, and then placed on a compressed airflow table for drying.

Low pressure process for continuous fiber reinforced polyamic acid resin matrix composite laminates

NASA Technical Reports Server (NTRS)

Druyun, Darleen A. (Inventor); Hou, Tan-Hung (Inventor); Kidder, Paul W. (Inventor); Reddy, Rakasi M. (Inventor); Baucom, Robert M. (Inventor)

1994-01-01

A low pressure processor was developed for preparing a well-consolidated polyimide composite laminate. Prepreg plies were formed from unidirectional fibers and a polyamic acid resin solution. Molding stops were placed at the sides of a matched metal die mold. The prepreg plies were cut shorter than the length of the mold in the in-plane lateral direction and were stacked between the molding stops to a height which was higher than the molding stops. The plies were then compressed to the height of the stops and heated to allow the volatiles to escape and to start the imidization reaction. After removing the stops from the mold, the heat was increased and 0 - 500 psi was applied to complete the imidization reaction. The heat and pressure were further increased to form a consolidated polyimide composite laminate.

Thermoplastic matrix composite processing model

NASA Technical Reports Server (NTRS)

Dara, P. H.; Loos, A. C.

1985-01-01

The effects the processing parameters pressure, temperature, and time have on the quality of continuous graphite fiber reinforced thermoplastic matrix composites were quantitatively accessed by defining the extent to which intimate contact and bond formation has occurred at successive ply interfaces. Two models are presented predicting the extents to which the ply interfaces have achieved intimate contact and cohesive strength. The models are based on experimental observation of compression molded laminates and neat resin conditions, respectively. Identified as the mechanism explaining the phenomenon by which the plies bond to themselves is the theory of autohesion (or self diffusion). Theoretical predictions from the Reptation Theory between autohesive strength and contact time are used to explain the effects of the processing parameters on the observed experimental strengths. The application of a time-temperature relationship for autohesive strength predictions is evaluated. A viscoelastic compression molding model of a tow was developed to explain the phenomenon by which the prepreg ply interfaces develop intimate contact.

Grinding aspheric and freeform micro-optical molds

NASA Astrophysics Data System (ADS)

Tohme, Yazid E.

2007-02-01

Fueled by the need for better performing optics, glass optics are now replacing plastic optics in many industrial and consumer electronic devices. One of these devices is the mobile phone camera. The optical sub-assembly in a mobile phone includes several micro lenses that are spherical and/or aspherical in shape and require form tolerances in the submicron range. These micro glass lenses are mass produced by a replication process known as glass press molding. The process entails the compression of a glass gob between two precise optical quality molds at an elevated temperature, usually near the transition temperature of the glass material. The elevated forces and temperatures required in the glass molding process limits the materials of the molds to very tough materials such as tungsten carbide or silicon carbide. These materials can withstand large pressing forces at high temperatures without any significant deformation. These materials offer great mechanical properties for glass press molding but they are also a challenge to machine to submicron accuracy. The work in this paper discusses a deterministic micro grinding manufacturing process referred to as wheel normal grinding, which is utilized to produce these optical quality molds. Wheel normal grinding is more accurate and more deterministic than most other grinding techniques and can produce molds to the form and finish tolerances required for optical molding. This method relies on the ability to recognize and compensate for grinding wheel wear and machine repeatable errors. Results will be presented to illustrate the accuracy of this micro grinding technique.

Influence of fiber length on flexural and impact properties of Zalacca Midrib fiber/HDPE by compression molding

NASA Astrophysics Data System (ADS)

Pamungkas, Agil Fitri; Ariawan, Dody; Surojo, Eko; Triyono, Joko

2018-02-01

The aim of the research is to investigate the effect of fiber length on the flexural and impact properties of the composite of Zalacca Midrib Fiber (ZMF)/HDPE. The process of making composite was using compression molding method. The variation of fiber length were 1 mm, 3 mm, 5 mm, 7 mm and 9 mm, at 30% fiber volume fraction. The flexural and impact test according to ASTM D790 and ASTM D5941, respectively. Observing fracture surface was examained by using Scanning Electron Microscopy (SEM). The results showed that the flexural and impact strengths would be increase with the increase of fiber length.

Correlation between some technological parameters and properties of composite material based on recycled tires and polymer binder

NASA Astrophysics Data System (ADS)

Plesuma, Renate; Malers, Laimonis

2015-04-01

The present article is dedicated to the determination of a possible connection between the composition, specific properties of the composite material and molding pressure as an important technological parameter. Apparent density, Shore C hardness, compressive modulus of elasticity and compressive stress at 10% deformation was determined for composite material samples. Definite formation conditions - varying molding pressure conditions at ambient temperature and corresponding relative air humiditywere realized. The results obtained showed a significant effect of molding pressure on the apparent density, mechanical properties of composite material as well as on the compressive stress change at a cyclic mode of loading. Some general regularities were determined - mechanical properties of the composite material, as well as values of Shore C hardness increases with an increase of molding pressure.

Highly oriented carbon fiber–polymer composites via additive manufacturing

DOE PAGES

Tekinalp, Halil L.; Kunc, Vlastimil; Velez-Garcia, Gregorio M.; ...

2014-10-16

Additive manufacturing, diverging from traditional manufacturing techniques, such as casting and machining materials, can handle complex shapes with great design flexibility without the typical waste. Although this technique has been mainly used for rapid prototyping, interest is growing in using this method to directly manufacture actual parts of complex shape. To use 3D-printing additive manufacturing in wide spread applications, the technique and the feedstock materials require improvements to meet the mechanical requirements of load-bearing components. Thus, we investigated the short fiber (0.2 mm to 0.4 mm) reinforced acrylonitrile-butadiene-styrene composites as a feedstock for 3D-printing in terms of their processibility, microstructuremore » and mechanical performance; and also provided comparison with traditional compression molded composites. The tensile strength and modulus of 3D-printed samples increased ~115% and ~700%, respectively. 3D-printer yielded samples with very high fiber orientation in printing direction (up to 91.5 %), whereas, compression molding process yielded samples with significantly less fiber orientation. Microstructure-mechanical property relationships revealed that although the relatively high porosity is observed in the 3D-printed composites as compared to those produced by the conventional compression molding technique, they both exhibited comparable tensile strength and modulus. Furthermore, this phenomena is explained based on the changes in fiber orientation, dispersion and void formation.« less

Additive Manufacturing of Parts and Tooling in Robotic Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Love, Lonnie J.; Hassen, Ahmed A.; Chesser, Phillip C.

ORNL worked with Transcend Robotics, LLC to explore additive manufacturing of the two-piece compression body for their ARTI mobile robot platform. Extrusion compression molding was identified as an effective means of manufacturing these parts. ORNL consulted on modifications to the housing design to accommodate the selected manufacturing process. Parts were printed using ORNL's FDM machines for testing and evaluation of the design as a precursor to molding the parts. The assembly and evaluation of the parts proved favorable and minor design changes to improve assembly and performance were identified.The goal is to develop a light weight and rugged two-part roboticmore » enclosure for an unmanned ground vehicle UGV) that will be used in search and rescue applications. The FDM parts fabricated by ORNL allowed Transcend Robotics to assemble a prototype robot and verify that the new parts will meet the performance requirements. ORNL fabricated enclosure parts out of ABS and Nylon 12 materials such that the design could be tested prior to fabricating tooling for compression molding of Nylon 6 with carbon fiber fill. The robot was performance tested and compared with the previous manufacturing techniques and found to have superior performance.« less

Fabrication of spherical microlens array by combining lapping on silicon wafer and rapid surface molding

NASA Astrophysics Data System (ADS)

Liu, Xiaohua; Zhou, Tianfeng; Zhang, Lin; Zhou, Wenchen; Yu, Jianfeng; Lee, L. James; Yi, Allen Y.

2018-07-01

Silicon is a promising mold material for compression molding because of its properties of hardness and abrasion resistance. Silicon wafers with carbide-bonded graphene coating and micro-patterns were evaluated as molds for the fabrication of microlens arrays. This study presents an efficient but flexible manufacturing method for microlens arrays that combines a lapping method and a rapid molding procedure. Unlike conventional processes for microstructures on silicon wafers, such as diamond machining and photolithography, this research demonstrates a unique approach by employing precision steel balls and diamond slurries to create microlenses with accurate geometry. The feasibility of this method was demonstrated by the fabrication of several microlens arrays with different aperture sizes and pitches on silicon molds. The geometrical accuracy and surface roughness of the microlens arrays were measured using an optical profiler. The measurement results indicated good agreement with the optical profile of the design. The silicon molds were then used to copy the microstructures onto polymer substrates. The uniformity and quality of the samples molded through rapid surface molding were also assessed and statistically quantified. To further evaluate the optical functionality of the molded microlens arrays, the focal lengths of the microlens arrays were measured using a simple optical setup. The measurements showed that the microlens arrays molded in this research were compatible with conventional manufacturing methods. This research demonstrated an alternative low-cost and efficient method for microstructure fabrication on silicon wafers, together with the follow-up optical molding processes.

Development of fire resistant, nontoxic aircraft interior materials

NASA Technical Reports Server (NTRS)

Haley, G.; Silverman, B.; Tajima, Y.

1976-01-01

All available newly developed nonmetallic polymers were examined for possible usage in developing fire resistant, nontoxic nonmetallic parts or assemblies for aircraft interiors. Specifically, feasibility for the development of clear films for new decorative laminates, compression moldings, injection molded parts, thermoformed plastic parts, and flexible foams were given primary considerations. Preliminary data on the flame resistant characteristics of the materials were obtained. Preliminary toxicity data were generated from samples of materials submitted from the contractor. Preliminary data on the physical characteristics of various thermoplastic materials to be considered for either compression molded, injection molded, or thermoformed parts were obtained.

Modes of fossil preservation

USGS Publications Warehouse

Schopf, J.M.

1975-01-01

The processes of geologic preservation are important for understanding the organisms represented by fossils. Some fossil differences are due to basic differences in organization of animals and plants, but the interpretation of fossils has also tended to be influenced by modes of preservation. Four modes of preservation generally can be distinguished: (1) Cellular permineralization ("petrifaction") preserves anatomical detail, and, occasionally, even cytologic structures. (2) Coalified compression, best illustrated by structures from coal but characteristic of many plant fossils in shale, preserves anatomical details in distorted form and produces surface replicas (impressions) on enclosing matrix. (3) Authigenic preservation replicates surface form or outline (molds and casts) prior to distortion by compression and, depending on cementation and timing, may intergrade with fossils that have been subject to compression. (4) Duripartic (hard part) preservation is characteristic of fossil skeletal remains, predominantly animal. Molds, pseudomorphs, or casts may form as bulk replacements following dissolution of the original fossil material, usually by leaching. Classification of the kinds of preservation in fossils will aid in identifying the processes responsible for modifying the fossil remains of both animals and plants. ?? 1975.

Compression Molding of Composite of Recycled HDPE and Recycled Tire Particles

NASA Technical Reports Server (NTRS)

Liu, Ping; Waskom, Tommy L.; Chen, Zhengyu; Li, Yanze; Peng, Linda

1996-01-01

Plastic and rubber recycling is an effective means of reducing solid waste to the environment and preserving natural resources. A project aimed at developing a new composite material from recycled high density polyethylene (HDPE) and recycled rubber is currently being conducted at Eastern Illinois University. The recycled plastic pellets with recycled rubber particles are extruded into some HDPE/rubber composite strands. The strand can be further cut into pellets that can be used to fabricate other material forms or products. This experiment was inspired by the above-mentioned research activity. In order to measure Durometer hardness of the extruded composite, a specimen with relatively large dimensions was needed. Thus, compression molding was used to form a cylindrical specimen of 1 in. diameter and 1 in. thickness. The initial poor quality of the molded specimen prompted a need to optimize the processing parameters such as temperature, holding time, and pressure. Design of experiment (DOE) was used to obtain optimum combination of the parameters.

Molding apparatus. [for thermosetting plastic compositions

NASA Technical Reports Server (NTRS)

Heier, W. C. (Inventor)

1974-01-01

Apparatus for compression molding of thermosetting plastics compositions including interfitting hollow male and female components is reported. The components are adapted to be compressed to form a rocket nozzle in a cavity. A thermal jacket is provided exteriorly adjacent to the female component for circulating a thermal transfer fluid to effect curing of a thermosetting plastics material being molded. Each of the male and female components is provided with suitable inlets and outlets for circulating a thermal transfer fluid.

An improved compression molding technology for continuous fiber reinforced composite laminate. Part 1: AS-4/LaRC-TPI 1500 (HFG) Prepreg system

NASA Technical Reports Server (NTRS)

Hou, Tan-Hung; Kidder, Paul W.; Reddy, Rakasi M.

1991-01-01

Poor processability of fiber reinforced high performance polyimide thermoplastic resin composites is a well recognized issue which, in many cases, prohibits the fabrication of composite parts with satisfactorily consolidated quality. Without modifying the resin matrix chemistry, improved compression modeling procedures were proposed and investigated with the AS-4/LaRC-TPI 1500 High Flow Grade (HFG) prepreg system. Composite panels with excellent C-scans can be consistently molded by this method under 700 F and a consolidation pressure as low as 100 psi. A mechanism for the consolidation of the composite under this improved molding technique is discussed. This mechanism reveals that a certain degree of matrix shear and tow filament slippage and nesting between plies occur during consolidation, which leads to a reduction of the consolidating pressure necessary to offset the otherwise intimate inter fiber-fiber contact and consequently achieves a better consolidation quality. Outstanding short beam shear strength and flexural strength were obtained from the molded panels. A prolonged consolidation step under low pressure, i.e., 100 psi at 700 F for 75 minutes, was found to significantly enhance the composite mechanical properties.

Low Cost Manufacturing Approach of High Temperature PMC Components

NASA Technical Reports Server (NTRS)

Kannmacher, Kevin

1997-01-01

The overall objective is to develop a satisfactory sheet molding compound (SMC) of a high temperature polyimide, such as PMR-11-50, VCAP-75, or NB2-76, and to develop compression molding processing parameters for a random, chopped fiber, high temperature, sheet molding compound that will be more affordable than the traditional hand lay-up fabrication methods. Compression molding will reduce manufacturing costs of composites by: (1) minimizing the conventional machining required after fabrication due to the use of full 360 deg matched tooling, (2) reducing fabrication time by minimizing the intensive hand lay-up operations associated with individual ply fabrication techniques, such as ply orientation and ply count and (3) possibly reducing component mold time by advanced B-staging prior to molding. This program is an integral part of Allison's T406/AE engine family's growth plan, which will utilize technologies developed under NASA's Sub-sonic Transport (AST) programs, UHPTET initiatives, and internally through Allison's IR&D projects. Allison is aggressively pursuing this next generation of engines, with both commercial and military applications, by reducing the overall weight of the engine through the incorporation of advanced, lightweight, high temperature materials, such as polymer matrix composites. This infusion of new materials into the engine is also a major factor in reducing engine cost because it permits the use of physically smaller structural components to achieve the same thrust levels as the generation that it replaced. A lighter, more efficient propulsion system translates to a substantial cost and weight savings to an airframe's structure.

Low cost tooling material and process for graphite and Kevlar composites

NASA Technical Reports Server (NTRS)

Childs, William I.

1987-01-01

An Extruded Sheet Tooling Compound (ESTC) was developed for use in quickly building low cost molds for fabricating composites. The ESTC is a very highly mineral-filled resin system formed into a 6 mm thick sheet. The sheet is laid on the pattern, vacuum (bag) is applied to remove air from the pattern surface, and the assembly is heat cured. The formed ESTC is then backed and/or framed and ready for use. The cured ESTC exhibits low coefficient of thermal expansion and maintains strength at temperatures of 180 to 200 C. Tools were made and used successfully for: Compression molding of high strength epoxy sheet molding compound, stamping of aluminum, resin transfer molding of polyester, and liquid resin molding of polyester. Several variations of ESTC can be made for specific requirements. Higher thermal conductivity can be achieved by using an aluminum particle filler. Room temperature gel is possible to allow use of foam patterns.

Development of improved asbestos reinforced phenolic insulating composites (optimization of physical properties as a function of molding technique and post cure conditions)

NASA Technical Reports Server (NTRS)

Hedges, L. M. (Editor)

1973-01-01

Detailed data are presented on phenolic-glass and phenolic-asbestos compounds which compare the effect of compression molding without degas to the effects of four variations of compression molding. These variations were designed to improve elimination of entrapped volatiles and the volatile products of the condensate reaction associated with the cure of phenolic resins. The utilization of conventional methods of degas plus degas by vacuum and directional heat flow methods are involved. Detailed data are also presented on these same compounds, comparing the effect of changes in post-bake time, and post-bake temperature for the five molding techniques.

High Cost/High Risk Components to Chalcogenide Molded Lens Model: Molding Preforms and Mold Technology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bernacki, Bruce E.

2012-10-05

This brief report contains a critique of two key components of FiveFocal's cost model for glass compression molding of chalcogenide lenses for infrared applications. Molding preforms and mold technology have the greatest influence on the ultimate cost of the product and help determine the volumes needed to select glass molding over conventional single-point diamond turning or grinding and polishing. This brief report highlights key areas of both technologies with recommendations for further study.

Processing and Properties of Vacuum Assisted Resin Transfer Molded Phenylethynyl Terminated Imide Composites

NASA Technical Reports Server (NTRS)

Cano, Roberto J.; Ghose, Sayata; Watson, Kent A.; Chunchu, Prasad B.; Jensen, Brian J.; Connell, John W.

2012-01-01

Polyimide composites are very attractive for applications that require a high strength to weight ratio and thermal stability. Recent work at NASA Langley Research Center (LaRC) has concentrated on developing new polyimide resin systems that can be processed without the use of an autoclave for advanced aerospace applications. Due to their low melt viscosities and long melt stability, certain phenylethynyl terminated imides (PETI) can be processed into composites using high temperature vacuum assisted resin transfer molding (HT-VARTM). VARTM has shown the potential to reduce the manufacturing cost of composite structures. In the current study, two PETI resins, LARC(Trademark) PETI-330 and LARC(Trademark) PETI-9, were infused into carbon fiber preforms at 260 C and cured at temperatures up to 371 C. Photomicrographs of polished cross sections were taken and void contents, determined by acid digestion, were below 4.5%. Mechanical properties including short block compression (SBC), compression after impact (CAI), and open hole compression (OHC) were determined at room temperature, 177 C, and 288 C. Both PETI-9 and PETI-330 composites demonstrated very good retention of mechanical properties at elevated temperatures. SBC and OHC properties after aging for 1000 hours at temperatures up to 288 C were also determined.

Mathematical modeling of the in-mold coating process for injection-molded thermoplastic parts

NASA Astrophysics Data System (ADS)

Chen, Xu

In-Mold Coating (IMC) has been successfully used for many years for exterior body panels made from compression molded Sheet Molding Compound (SMC). The coating material is a single component reactive fluid, designed to improve the surface quality of SMC moldings in terms of functional and cosmetic properties. When injected onto a cured SMC part, IMC cures and bonds to provide a pain-like surface. Because of its distinct advantages, IMC is being considered for application to injection molded thermoplastic parts. For a successful in mold coating operation, there are two key issues related to the flow of the coating. First, the injection nozzle should be located such that the thermoplastic substrate is totally covered and the potential for air trapping is minimized. The selected location should be cosmetically acceptable since it most likely will leave a mark on the coated surface. The nozzle location also needs to be accessible for easy of maintenance. Secondly, the hydraulic force generated by the coating injection pressure should not exceed the available clamping tonnage. If the clamping force is exceeded, coating leakage will occur. In this study, mathematical models for IMC flow on the compressible thermoplastic substrate have been developed. Finite Difference Method (FDM) is first used to solve the 1 dimensional (1D) IMC flow problem. In order to investigate the application of Control Volume based Finite Element Method (CV/FEM) to more complicated two dimensional IMC flow, that method is first evaluated by solving the 1D IMC flow problem. An analytical solution, which can be obtained when a linear relationship between the coating thickness and coating injection pressure is assumed, is used to verify the numerical results. The mathematical models for the 2 dimensional (2D) IMC flow are based on the generalized Hele-Shaw approximation. It has been found experimentally that the power law viscosity model adequately predicts the rheological behavior of the coating. The compressibility of the substrate is modeled by the 2-domain Tait PVT equation. CV/FEM is used to solve the discretized governing equations. A computer code has been developed to predict the fill pattern of the coating and the injection pressure. A number of experiments have been conducted to verify the numerical predictions of the computer code. It has been found both numerically and experimentally that the substrate thickness plays a significant role on the IMC fill pattern.

Pulp extrusion at ultra-high consistencies : selection of water soluble polymers for process optimization

Treesearch

C. Tim Scott

2002-01-01

Pulp extrusion at ultra-high consistencies (20% to 40% solids) is a new process developed at USDA Forest Service, Forest Products Laboratory (FPL) to convert recovered papers, wastepaper, and papermill residuals into solid sheets or profiles for compression molding. This process requires adding a water-soluble polymer (WSP) to alter the rheological properties of the...

A novel tool to standardize rheology testing of molten polymers for pharmaceutical applications.

PubMed

Treffer, Daniel; Troiss, Alexander; Khinast, Johannes

2015-11-10

Melt rheology provides information about material properties that are of great importance for equipment design and simulations, especially for novel pharmaceutical manufacturing operations, including extrusion, injection molding or 3d printing. To that end, homogeneous samples must be prepared, most commonly via compression or injection molding, both of which require costly equipment and might not be applicable for shear- and heat-sensitive pharmaceutical materials. Our study introduces a novel vacuum compression molding (VCM) tool for simple preparation of thermoplastic specimens using standard laboratory equipment: a hot plate and a vacuum source. Sticking is eliminated by applying polytetrafluoroethylene (PTFE) coated separation foils. The evacuation of the tool leads to compression of the sample chamber, which is cost-efficient compared to conventional methods, such as compression molding or injection molding that require special equipment. In addition, this compact design reduces the preparation time and the heat load. The VCM tool was used to prepare samples for a rheological study of three pharmaceutical polymers (Soluplus(®), Eudragit(®)E, EVA Rowalit(®) 300-1/28). The prepared samples were without any air inclusions or voids, and the measurements had a high reproducibility. All relative standard deviations were below 3%. The obtained data were fitted to the Carreau-Yasuda model and time-temperature superposition was applied. Copyright © 2015 Elsevier B.V. All rights reserved.

Fabrication of metallic microstructures by micromolding nanoparticles

DOEpatents

Morales, Alfredo M.; Winter, Michael R.; Domeier, Linda A.; Allan, Shawn M.; Skala, Dawn M.

2002-01-01

A method is provided for fabricating metallic microstructures, i.e., microcomponents of micron or submicron dimensions. A molding composition is prepared containing an optional binder and nanometer size (1 to 1000 nm in diameter) metallic particles. A mold, such as a lithographically patterned mold, preferably a LIGA or a negative photoresist mold, is filled with the molding composition and compressed. The resulting microstructures are then removed from the mold and the resulting metallic microstructures so provided are then sintered.

Phenolic Molding Compounds

NASA Astrophysics Data System (ADS)

Koizumi, Koji; Charles, Ted; de Keyser, Hendrik

Phenolic Molding Compounds continue to exhibit well balanced properties such as heat resistance, chemical resistance, dimensional stability, and creep resistance. They are widely applied in electrical, appliance, small engine, commutator, and automotive applications. As the focus of the automotive industry is weight reduction for greater fuel efficiency, phenolic molding compounds become appealing alternatives to metals. Current market volumes and trends, formulation components and its impact on properties, and a review of common manufacturing methods are presented. Molding processes as well as unique advanced techniques such as high temperature molding, live sprue, and injection/compression technique provide additional benefits in improving the performance characterisitics of phenolic molding compounds. Of special interest are descriptions of some of the latest innovations in automotive components, such as the phenolic intake manifold and valve block for dual clutch transmissions. The chapter also characterizes the most recent developments in new materials, including long glass phenolic molding compounds and carbon fiber reinforced phenolic molding compounds exhibiting a 10-20-fold increase in Charpy impact strength when compared to short fiber filled materials. The role of fatigue testing and fatigue fracture behavior presents some insight into long-term reliability and durability of glass-filled phenolic molding compounds. A section on new technology outlines the important factors to consider in modeling phenolic parts by finite element analysis and flow simulation.

Electroforming of optical tooling in high-strength Ni-Co alloy

NASA Astrophysics Data System (ADS)

Stein, Berl

2003-05-01

Plastic optics are often mass produced by injection, compression or injection-compression molding. Optical quality molds can be directly machined in appropriate materials (tool steels, electroless nickel, aluminum, etc.), but much greater cost efficiency can be achieved with electroformed modl inserts. Traditionally, electroforming of optical quality mold inserts has been carried out in nickel, a material much softer than tool steels which, when hardened to 45 - 50 HRc usually exhibit high wear resistance and long service life (hundreds of thousands of impressions per mold). Because of their low hardness (< 20 HRc), nickel molds can produce only tens of thousands of parts before they are scrapped due to wear or accidental damage. This drawback prevented their wider usage in general plastic and optical mold making. Recently, NiCoForm has developed a proprietary Ni-CO electroforming bath combining the high strength and wear resistance of the alloy with the low stress and high replication fidelity typical of pure nickel electroforming. This paper will outline the approach to electroforming of optical quality tooling in low stress, high strength Ni-Co alloy and present several examples of electroformed NiColoy mold inserts.

Evaluation of the microstructure, secondary dendrite arm spacing, and mechanical properties of Al-Si alloy castings made in sand and Fe-Cr slag molds

NASA Astrophysics Data System (ADS)

Narasimha Murthy, I.; Babu Rao, J.

2017-07-01

The microstructure and mechanical properties of as-cast A356 (Al-Si) alloy castings were investigated. A356 alloy was cast into three different molds composed of sand, ferrochrome (Fe-Cr) slag, and a mixture of sand and Fe-Cr. A sodium silicate-CO2 process was used to make the necessary molds. Cylindrical-shaped castings were prepared. Cast products with no porosity and a good surface finish were achieved in all of the molds. These castings were evaluated for their metallography, secondary dendrite arm spacing (SDAS), and mechanical properties, including hardness, compression, tensile, and impact properties. Furthermore, the tensile and impact samples were analyzed by fractography. The results show that faster heat transfer in the Fe-Cr slag molds than in either the silica sand or mixed molds led to lower SDAS values with a refined microstructure in the products cast in Fe-Cr slag molds. Consistent and enhanced mechanical properties were observed in the slag mold products than in the castings obtained from either sand or mixed molds. The fracture surface of the slag mold castings shows a dimple fracture morphology with a transgranular fracture nature. However, the fracture surfaces of the sand mold castings display brittle fracture. In conclusion, products cast in Fe-Cr slag molds exhibit an improved surface finish and enhanced mechanical properties compared to those of products cast in sand and mixed molds.

Wooden wind turbine blade manufacturing process

DOEpatents

Coleman, Clint

1986-01-01

A wooden wind turbine blade is formed by laminating wood veneer in a compression mold having the exact curvature needed for one side of the blade, following which the other side of the blade is ground flat along its length but twisted with respect to the blade axis.

In vitro cytotoxicity and in vivo osseointergration properties of compression-molded HDPE-HA-Al2O3 hybrid biocomposites.

PubMed

Tripathi, Garima; Gough, Julie E; Dinda, Amit; Basu, Bikramjit

2013-06-01

The aim of this study was to investigate the in vivo biocompatibility in terms of healing of long segmental bone defect in rabbit model as well as in vitro cytotoxicity of eluates of compression-molded High density polyethylene (HDPE)-hydroxyapatite (HA)-aluminum oxide (Al2O3) composite-based implant material. Based on the physical property in terms of modulus and strength properties, as reported in our recent publication, HDPE-40 wt % HA and HDPE-20 wt % HA-20 wt % Al2O3 hybrid composites were used for biocompatibility assessment. Osteoblasts cells were cultured in conditioned media, which contains varying amount of composite eluate (0.01, 0.1, and 1.0 wt %). In vitro, the eluates did not exhibit any significant negative impact on proliferation, mineralization or on morphology of human osteoblast cells. In vivo, the histological assessment revealed neobone formation at the bone/implant interface, characterized by the presence of osteoid and osteoblasts. The observation of osteoclastic activity indicates the process of bone remodeling. No inflammation to any noticeable extent was observed at the implantation site. Overall, the combination of in vitro and in vivo results are suggestive of potential biomedical application of compression-molded HDPE- 20 wt % HA- 20 wt % Al2O3 composites to heal long segmental bone defects without causing any toxicity of bone cells. Copyright © 2012 Wiley Periodicals, Inc.

Determination of Machining Parameters of Corn Byproduct Filled Plastics

USDA-ARS?s Scientific Manuscript database

In a collaborative project between the USDA and Northern Illinois University, the use of ethanol corn processing by-products as bio-filler materials in the compression molding of phenolic plastics has been studied. This paper reports on the results of a machinability study in the milling of various ...

Determining Machining Parameters of Corn Byproduct Filled Plastics

USDA-ARS?s Scientific Manuscript database

In a collaborative project between the USDA and Northern Illinois University, the use of corn ethanol processing byproducts (i.e., DDGS) as bio-filler materials in the compression molding of phenolic plastics has been studied. This paper reports on the results of a machinability study in the milling...

Effect of coal filler on the properties of soy protein plastics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, G.H.; Zhou, A.N.; Hu, M.B.

2006-11-15

The influence of ultrafine coal filler (UFC) content on tensile properties, water absorption, and biodegradability of soy protein plastics were investigated. The addition of UFC in the soy protein plastics, with different content of glycerol as a plasticizer, was at different ratio varying from 10:0 to 6:4. Blend sheets of the soy protein composites were prepared by the compression molding processing. The results show that, with 23.08 wt % glycerol, the tensile strength and elongation at break for the soy protein sheet with coal filler (range from 5 to 30 parts) can be enhanced as compared with nonfilled soy proteinmore » plastics. Water resistance of the soy protein plastics improves with the increase in UFC content. The derivative thermogravimetry (DTG) curves indicate a double-stage degradation process for defatted soy flour (SPF), while three-stage degradation process for soy plastics and the soy protein composites. FT-IR, XPS, and SEM were applied to study the interfacial interaction between coal macromolecules and soy protein molecules in UFC filled soy protein plastics. The results demonstrated that there is strong interfacial interaction in the soy protein plastics caused by the compression molding processing.« less

Compression Molding and Novel Sintering Treatments for Alnico Type-8 Permanent Magnets in Near-Final Shape with Preferred Orientation

NASA Astrophysics Data System (ADS)

Kassen, Aaron G.; White, Emma M. H.; Tang, Wei; Hu, Liangfa; Palasyuk, Andriy; Zhou, Lin; Anderson, Iver E.

2017-09-01

Economic uncertainty in the rare earth (RE) permanent magnet marketplace, as well as in an expanding electric drive vehicle market that favors permanent magnet alternating current synchronous drive motors, motivated renewed research in RE-free permanent magnets like "alnico," an Al-Ni-Co-Fe alloy. Thus, high-pressure, gas-atomized isotropic type-8H pre-alloyed alnico powder was compression molded with a clean burn- out binder to near-final shape and sintered to density >99% of cast alnico 8 (full density of 7.3 g/cm3). To produce aligned sintered alnico magnets for improved energy product and magnetic remanence, uniaxial stress was attempted to promote controlled grain growth, avoiding directional solidification that provides alignment in alnico 9. Successful development of solid-state powder processing may enable anisotropically aligned alnico magnets with enhanced energy density to be mass-produced.

Effects of number of ply, compression temperature, pressure and time on mechanical properties of prepreg kenaf-polypropilene composites

NASA Astrophysics Data System (ADS)

Tomo, H. S. S.; Ujianto, O.; Rizal, R.; Pratama, Y.

2017-07-01

Composite material thermoplastic was prepared from polypropilen granule as matrix, kenaf fiber as reinforcement and grafted polypropylene copolymer maleic anhydride as coupling agent. Composite products were produced as sandwich structures using compression molding. This research aimed to observe the influence of number of ply, temperature, pressure, and compression time using factorial design. Effects of variables on tensile and flexural strength were analyzed. Experimental results showed that tensile and flexural strength were influenced by degradation, fiber compaction, and matrix - fiber interaction mechanisms. Flexural strength was significantly affected by number of ply and its interaction to another process parameters (temperature, pressure, and compression time), but no significant effect of process parameters on tensile strength. The highest tensile strength (62.0 MPa) was produced at 3 ply, 210 °C, 50 Bar, and 3 min compression time (low, high, high, low), while the highest flexural strength (80.3 MPa) was produced at 3 ply, 190 °C, 50 Bar, and 3 min compression time (low, low, high, low).

Tuning the superstructure of ultrahigh-molecular-weight polyethylene/low-molecular-weight polyethylene blend for artificial joint application.

PubMed

Xu, Ling; Chen, Chen; Zhong, Gan-Ji; Lei, Jun; Xu, Jia-Zhuang; Hsiao, Benjamin S; Li, Zhong-Ming

2012-03-01

An easy approach was reported to achieve high mechanical properties of ultrahigh-molecular-weight polyethylene (UHMWPE)-based polyethylene (PE) blend for artificial joint application without the sacrifice of the original excellent wear and fatigue behavior of UHMWPE. The PE blend with desirable fluidity was obtained by melt mixing UHMWPE and low molecular weight polyethylene (LMWPE), and then was processed by a modified injection molding technology-oscillatory shear injection molding (OSIM). Morphological observation of the OSIM PE blend showed LMWPE contained well-defined interlocking shish-kebab self-reinforced superstructure. Addition of a small amount of long chain polyethylene (2 wt %) to LMWPE greatly induced formation of rich shish-kebabs. The ultimate tensile strength considerably increased from 27.6 MPa for conventional compression molded UHMWPE up to 78.4 MPa for OSIM PE blend along the flow direction and up to 33.5 MPa in its transverse direction. The impact strength of OSIM PE blend was increased by 46% and 7% for OSIM PE blend in the direction parallel and vertical to the shear flow, respectively. Wear and fatigue resistance were comparable to conventional compression molded UHMWPE. The superb performance of the OSIM PE blend was originated from formation of rich interlocking shish-kebab superstructure while maintaining unique properties of UHMWPE. The present results suggested the OSIM PE blend has high potential for artificial joint application. © 2012 American Chemical Society

Fabrication of low-cost beta-type Ti-Mn alloys for biomedical applications by metal injection molding process and their mechanical properties.

PubMed

Santos, Pedro Fernandes; Niinomi, Mitsuo; Liu, Huihong; Cho, Ken; Nakai, Masaaki; Itoh, Yoshinori; Narushima, Takayuki; Ikeda, Masahiko

2016-06-01

Titanium and its alloys are suitable for biomedical applications owing to their good mechanical properties and biocompatibility. Beta-type Ti-Mn alloys (8-17 mass% Mn) were fabricated by metal injection molding (MIM) as a potential low cost material for use in biomedical applications. The microstructures and mechanical properties of the alloys were evaluated. For up to 13 mass% Mn, the tensile strength (1162-938MPa) and hardness (308-294HV) of the MIM fabricated alloys are comparable to those of Ti-Mn alloys fabricated by cold crucible levitation melting. Ti-9Mn exhibits the best balance of ultimate tensile strength (1046MPa) and elongation (4.7%) among the tested alloys, and has a Young's modulus of 89GPa. The observed low elongation of the alloys is attributed to the combined effects of high oxygen content, with the presence of interconnected pores and titanium carbides, the formation of which is due to carbon pickup during the debinding process. The elongation and tensile strength of the alloys decrease with increasing Mn content. The Ti-Mn alloys show good compressive properties, with Ti-17Mn showing a compressive 0.2% proof stress of 1034MPa, and a compressive strain of 50%. Copyright © 2016 Elsevier Ltd. All rights reserved.

Mechanical characterization of 2D, 2D stitched, and 3D braided/RTM materials

NASA Technical Reports Server (NTRS)

Deaton, Jerry W.; Kullerd, Susan M.; Portanova, Marc A.

1993-01-01

Braided composite materials have potential for application in aircraft structures. Fuselage frames, floor beams, wing spars, and stiffeners are examples where braided composites could find application if cost effective processing and damage tolerance requirements are met. Another important consideration for braided composites relates to their mechanical properties and how they compare to the properties of composites produced by other textile composite processes being proposed for these applications. Unfortunately, mechanical property data for braided composites do not appear extensively in the literature. Data are presented in this paper on the mechanical characterization of 2D triaxial braid, 2D triaxial braid plus stitching, and 3D (through-the-thickness) braid composite materials. The braided preforms all had the same graphite tow size and the same nominal braid architectures, (+/- 30 deg/0 deg), and were resin transfer molded (RTM) using the same mold for each of two different resin systems. Static data are presented for notched and unnotched tension, notched and unnotched compression, and compression after impact strengths at room temperature. In addition, some static results, after environmental conditioning, are included. Baseline tension and compression fatigue results are also presented, but only for the 3D braided composite material with one of the resin systems.

Fuel cell collector plate and method of fabrication

DOEpatents

Braun, James C.; Zabriskie, Jr., John E.; Neutzler, Jay K.; Fuchs, Michel; Gustafson, Robert C.

2001-01-01

An improved molding composition is provided for compression molding or injection molding a current collector plate for a polymer electrolyte membrane fuel cell. The molding composition is comprised of a polymer resin combined with a low surface area, highly-conductive carbon and/or graphite powder filler. The low viscosity of the thermoplastic resin combined with the reduced filler particle surface area provide a moldable composition which can be fabricated into a current collector plate having improved current collecting capacity vis-a-vis comparable fluoropolymer molding compositions.

Modeling and control of flow during impregnation of heterogeneous porous media, with application to composite mold-filling processes

NASA Astrophysics Data System (ADS)

Bickerton, Simon

Liquid Composite Molding (LCM) encompasses a growing list of composite material manufacturing techniques. These processes have provided the promise for complex fiber reinforced plastics parts, manufactured from a single molding step. In recent years a significant research effort has been invested in development of process simulations, providing tools that have advanced current LCM technology and broadened the range of applications. The requirement for manufacture of larger, more complex parts has motivated investigation of active control of LCM processes. Due to the unlimited variety of part geometries that can be produced, finite element based process simulations will be used to some extent in design of actively controlled processes. Ongoing efforts are being made to improve material parameter specification for process simulations, increasing their value as design tools. Several phenomena occurring during mold filling have been addressed through flow visualization experimentation and analysis of manufactured composite parts. The influence of well defined air channels within a mold cavity is investigated, incorporating their effects within existing filling simulations. Three different flow configurations have been addressed, testing the application of 'equivalent permeabilities', effectively approximating air channels as representative porous media. LCM parts having doubly curved regions require preform fabrics to undergo significant, and varying deformation throughout a mold cavity. Existing methods for predicting preform deformation, and the resulting permeability distribution have been applied to a conical mold geometry. Comparisons between experiment and simulation are promising, while the geometry studied has required large deformation over much of the part, shearing the preform fabric beyond the scope of the models applied. An investigational study was performed to determine the magnitude of effect, if any, on mold filling caused by corners within LCM mold cavities. The molds applied in this study have required careful consideration of cavity thickness variations. Any effects on mold filling due to corner radii have been overshadowed by those due to preform compression. While numerical tools are available to study actively controlled mold filling in a virtual environment, some development is required for the physical equipment to implement this in practice. A versatile, multiple line fluid injection system is developed here. The equipment and control algorithms employed have provided servo control of flow rate, or injection pressure, and have been tested under very challenging conditions. The single injection line developed is expanded to a multiple line system, and shows great potential for application to actual resin systems. A case study is presented, demonstrating design and implementation of a simple actively controlled injection scheme. The experimental facility developed provides an excellent testbed for application of actively controlled mold filling concepts, an area that is providing great promise for the advancement of LCM processes.

Rational preparation of waste coal mixture for production of bricks by the method of compression molding

NASA Astrophysics Data System (ADS)

Stolboushkin, A. Yu; Ivanov, A. I.; Temlyantsev, M. V.; Fomina, O. A.

2016-10-01

Rational preparation of the mixture containing technogenic raw material - waste coal for the production of wall ceramics is developed. It was established that the technology of high-quality ceramic bricks requires: grinding of raw materials to class 0.3 + 0 mm, its aggregation in the intensive mixers into granules 1-3 mm, compression molding of adobe to plastic deformation of granules, drying and firing.

A simulated RTM process for fabricating polyimide (AMB-21) carbon fiber composites

NASA Technical Reports Server (NTRS)

Avva, V. Sarma; Sadler, Robert L.; Thomas, Shanon

1995-01-01

An experimental polyimide matrix, AMB-21 - supplied by NASA/LeRC, was especially formulated to be non-carcinogenic. It was also expected to be amenable to a Resin Transfer Molding Process (RTM). AMB-21 is a solid at room temperature and must be heated to a very high temperature to obtain a fluid state. However, even after heating it to a realistic high temperature, it was found to be too viscous for use in a RTM process. As a result, a promising approach was experimented leading to the introduction of the resin into a solvent solution in order to obtain a viscosity suitable for RTM. A mixture of methanol and tetrahydroferone was found to be a suitable solvent mixture. The matrix solution was introduced into carbon-fiber preform using two techniques: (1) injection of matrix into a Resin Transfer Mold after positioning the preform into the 'mold cavity', and (2) infiltration of matrix into the preform using the 'autoclave through-the-thickness transfer process'. After completing the resin transfer (infiltration) process, the 'filled' preform was heated to 300 F for one hour to reduce the solvent content. The temperature was then increased to 400 F under a vacuum to complete the solvent evaporation and to remove volatile products of the polyimide imidization. The impregnated preform was removed from the mold and press-cured at 200 psi and 600 FF for two hours. The resulting panel was found to be of reasonably good quality. This observation was based on the results obtained from short beam shear strength (700-8000 psi) tests and microscopic examination of the cross-section indicating a very low level of porosity. Further, the flash around the molded panels from the compression molding was free of porosity indicating the removal of volatiles, solvents, and other imidization products. Based on these studies, a new RTM mold containing a diaphragm capable of applying 200 psi at 600 F has been designed and constructed with the expectation that it will allow the incorporation of all of the above processing steps, including the consolidation with the preform in the mold cavity. Moreover, the new diaphragm design will enable to process larger preform panels. Processing studies with the diaphragm mold are being initiated.

Effect of injection parameters on mechanical and physical properties of super ultra-thin wall propylene packaging by Taguchi method

NASA Astrophysics Data System (ADS)

Ginghtong, Thatchanok; Nakpathomkun, Natthapon; Pechyen, Chiravoot

2018-06-01

The parameters of the plastic injection molding process have been investigated for the manufacture of a 64 oz. ultra-thin polypropylene bucket. The 3 main parameters, such as injection speed, melting temperature, holding pressure, were investigated to study their effect on the physical appearance and compressive strength. The orthogonal array of Taguchi's L9 (33) was used to carry out the experimental plan. The physical properties were measured and the compressive strength was determined using linear regression analysis. The differential scanning calorimeter (DSC) was used to analyze the crystalline structure of the product. The optimization results show that the proposed approach can help engineers identify optimal process parameters and achieve competitive advantages of energy consumption and product quality. In addition, the injection molding of the product includes 24 mm of shot stroke, 1.47 mm position transfer, 268 rpm screw speed, injection speed 100 mm/s, 172 ton clamping force, 800 kgf holding pressure, 0.9 s holding time and 1.4 s cooling time, make the products in the shape and proportion of the product satisfactory. The parameters of influence are injection speed 71.07%, melting temperature 23.31% and holding pressure 5.62%, respectively. The compressive strength of the product was able to withstand a pressure of up to 839 N before the product became plastic. The low melting temperature was caused by the superior crystalline structure of the super-ultra-thin wall product which leads to a lower compressive strength.

Compliant Buckled Foam Actuators and Application in Patient-Specific Direct Cardiac Compression.

PubMed

Mac Murray, Benjamin C; Futran, Chaim C; Lee, Jeanne; O'Brien, Kevin W; Amiri Moghadam, Amir A; Mosadegh, Bobak; Silberstein, Meredith N; Min, James K; Shepherd, Robert F

2018-02-01

We introduce the use of buckled foam for soft pneumatic actuators. A moderate amount of residual compressive strain within elastomer foam increases the applied force ∼1.4 × or stroke ∼2 × compared with actuators without residual strain. The origin of these improved characteristics is explained analytically. These actuators are applied in a direct cardiac compression (DCC) device design, a type of implanted mechanical circulatory support that avoids direct blood contact, mitigating risks of clot formation and stroke. This article describes a first step toward a pneumatically powered, patient-specific DCC design by employing elastomer foam as the mechanism for cardiac compression. To form the device, a mold of a patient's heart was obtained by 3D printing a digitized X-ray computed tomography or magnetic resonance imaging scan into a solid model. From this model, a soft, robotic foam DCC device was molded. The DCC device is compliant and uses compressed air to inflate foam chambers that in turn apply compression to the exterior of a heart. The device is demonstrated on a porcine heart and is capable of assisting heart pumping at physiologically relevant durations (∼200 ms for systole and ∼400 ms for diastole) and stroke volumes (∼70 mL). Although further development is necessary to produce a fully implantable device, the material and processing insights presented here are essential to the implementation of a foam-based, patient-specific DCC design.

Processing and Characterization of Cellulose Nanocrystals/Polylactic Acid Nanocomposite Films

Treesearch

Erin Sullivan; Robert Moon; Kyriaki Kalaitzidou

2015-01-01

The focus of this study is to examine the effect of cellulose nanocrystals (CNC) on the properties of polylactic acid (PLA) films. The films are fabricated via melt compounding and melt fiber spinning followed by compression molding. Film fracture morphology, thermal properties, crystallization behavior, thermo-mechanical behavior, and mechanical behavior were...

Innovative Approach for High Strength, High Thermal Conductive Composite Materials: Data Base

DTIC Science & Technology

2013-11-01

pitch fiber types, from which we were able to down select K6356U pitch fiber with balanced TC and strength properties. A prepreg processing line was...Creating a robust prepreg processing line to infuse unidirectional pitch fiber tape that can be used with other fibers…Pan-based carbon or glass...pitch fiber composites • Compression molding process outperforms autoclaving in mechanical and thermal properties using the same prepreg material and

VIEW OF INTERIOR OF SOUTHERN DUCTILE CASTING COMPANY, CENTERVILLE FOUNDRY ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

VIEW OF INTERIOR OF SOUTHERN DUCTILE CASTING COMPANY, CENTERVILLE FOUNDRY SHOWING MOLD MAKING WITH PNEWMATIC JOLT SQUEEZE COPE AND DRAG MOLDING MACHINES THAT INDIVIDUALLY MADE EITHER A COPE OR DRAG AND A SMALL WHEELED MATCHPLATE JOLT-SQUEEZE MACHINE THAT COMPRESSED AN ENTIRE MOLD AT A SINGLE TIME USING A DOUBLE-SIDED PATTERN (MATCHPLATE). ALSO SHOWN ARE RAILED PALLET CAR CONVEYORS THAT CARRIED COMPLETED MOLDS FROM MOLDING MACHINES TO POURING AREAS WHERE WORKERS USED SMALL OVERHEAD CRANE TO LIFT JACKETS AND WEIGHTS ONTO THE MOLDS TO HOLD THEM TOGETHER WHILE POURING. - Southern Ductile Casting Company, Centerville Foundry, 101 Airport Road, Centreville, Bibb County, AL

Spatially Targeted Activation of a Shape Memory, Polymer-Based, Reconfigurable Skin System

DTIC Science & Technology

2014-02-01

bone samples described in ASTM Standard D638 using a CNC router. Compression test samples were cured in an aluminum cylinder mold treated with mold...release with Teflon end plugs and cut to length with a small lathe . 2.2 Tensile/Compressive Tests Tensile tests were conducted on a MTS QTest/1L...fixture with a CNC mill and a decal applied to the front surface for tracking by the DIC system. Figure 10: Shear Test Sample with DIC Decal 10

Compact self-aligning assemblies with refractive microlens arrays made by contactless embossing

NASA Astrophysics Data System (ADS)

Schulze, Jens; Ehrfeld, Wolfgang; Mueller, Holger; Picard, Antoni

1998-04-01

The hybrid integration of microlenses and arrays of microlenses in micro-optical systems is simplified using contactless embossing of microlenses (CEM) in combination with LIGA microfabrication. CEM is anew fabrication technique for the production of precise refractive microlens arrays. A high precision matrix of holes made by LIGA technique is used as a compression molding tool to form the microlenses. The tool is pressed onto a thermoplastic sample which is heated close to the glass transformation temperature of the material. The material bulges into the openings of the molding tool due to the applied pressure and forms lens-like spherical structures. The name refers to the fact that the surface of the microlens does not get in contact with the compression molding tool during the shaping process and optical quality of the surface is maintained. Microlenses and arrays of microlenses with lens diameters from 30 micrometers up to 700 micrometers and numerical aperture values of up to 0.25 have been fabricated in different materials. Cost-effectiveness in the production process, excellent optical performance and the feature of easy replication are the main advantages of this technique. The most promising feature of this method is the possibility to obtain self- aligned assemblies then can be further integrated into a micro-optical bench setup. The CEM fabrication method in combination with LIGA microfabrication considerably enhances the hybrid integration in micro-optical devices which results in a more cost-effective production of compact micro-opto-electro-mechanical systems.

Process simulations for manufacturing of thick composites

NASA Astrophysics Data System (ADS)

Kempner, Evan A.

The availability of manufacturing simulations for composites can significantly reduce the costs associated with process development. Simulations provide a tool for evaluating the effect of processing conditions on the quality of parts produced without requiring numerous experiments. This is especially significant in parts that have troublesome features such as large thickness. The development of simulations for thick walled composites has been approached by examining the mechanics of resin flow and fiber deformation during processing, applying these evaluations to develop simulations, and evaluating the simulation with experimental results. A unified analysis is developed to describe the three-dimensional resin flow and fiber preform deformation during processing regardless of the manufacturing process used. It is shown how the generic governing evaluations in the unified analysis can be applied to autoclave molding, compression molding, pultrusion, filament winding, and resin transfer molding. A comparison is provided with earlier models derived individually for these processes. The evaluations described for autoclave curing were used to produce a one-dimensional cure simulation for autoclave curing of thick composites. The simulation consists of an analysis for heat transfer and resin flow in the composite as well as bleeder plies used to absorb resin removed from the part. Experiments were performed in a hot press to approximate curing in an autoclave. Graphite/epoxy laminates of 3 cm and 5 cm thickness were cured while monitoring temperatures at several points inside the laminate and thickness. The simulation predicted temperatures fairly closely, but difficulties were encountered in correlation of thickness results. This simulation was also used to study the effects of prepreg aging on processing of thick composites. An investigation was also performed on filament winding with prepreg tow. Cylinders were wound of approximately 12 mm thickness with pressure gages at the mandrel-composite interface. Cylinders were hoop wound with tensions ranging from 13-34 N. An analytical model was developed to calculate change in stress due to relaxation during winding. Although compressive circumferential stresses occurred throughout each of the cylinders, the magnitude was fairly low.

Compression Molding and Novel Sintering Treatments for Alnico Type-8 Permanent Magnets in Near-Final Shape with Preferred Orientation

DOE PAGES

Kassen, Aaron G.; White, Emma M. H.; Tang, Wei; ...

2017-07-14

We present economic uncertainty in the rare earth (RE) permanent magnet marketplace, as well as in an expanding electric drive vehicle market that favors permanent magnet alternating current synchronous drive motors, motivated renewed research in RE-free permanent magnets like “alnico,” an Al-Ni-Co-Fe alloy. Thus, high-pressure, gas-atomized isotropic type-8H pre-alloyed alnico powder was compression molded with a clean burn-out binder to near-final shape and sintered to density >99% of cast alnico 8 (full density of 7.3 g/cm 3). To produce aligned sintered alnico magnets for improved energy product and magnetic remanence, uniaxial stress was attempted to promote controlled grain growth, avoidingmore » directional solidification that provides alignment in alnico 9. Lastly, successful development of solid-state powder processing may enable anisotropically aligned alnico magnets with enhanced energy density to be mass-produced.« less

Effect of pH on compressive strength of some modification of mineral trioxide aggregate

PubMed Central

Saghiri, Mohammad A.; Garcia-Godoy, Franklin; Asatourian, Armen; Lotfi, Mehrdad; Khezri-Boukani, Kaveh

2013-01-01

Objectives: Recently, it was shown that NanoMTA improved the setting time and promoted a better hydration process which prevents washout and the dislodgment of this novel biomaterial in comparison with WTMA. This study analyzed the compressive strength of ProRoot WMTA (Dentsply), a NanoWMTA (Kamal Asgar Research Center), and Bioaggregate (Innovative Bioceramix) after its exposure to a range of environmental pH conditions during hydration. Study Design: After mixing the cements under aseptic condition and based on the manufacturers` recommendations, the cements were condensed with moderate force using plugger into 9 × 6 mm split molds. Each type of cement was then randomly divided into three groups (n=10). Specimens were exposed to environments with pH values of 4.4, 7.4, or 10.4 for 3 days. Cement pellets were compressed by using an Instron testing machine. Values were recorded and compared. Data were analyzed by using one-way analysis of variance and a post hoc Tukey’s test. Results: After 3 days, the samples were solid when probed with an explorer before removing them from the molds. The greatest mean compressive strength 133.19±11.14 MPa was observed after exposure to a pH value of 10.4 for NanoWMTA. The values decreased to 111.41±8.26 MPa after exposure to a pH value of 4.4. Increasing of pH had a significant effect on the compressive strength of the groups (p<0.001). The mean compressive strength for the NanoWMTA was statistically higher than for ProRoot WMTA and Bioaggregate (p<0.001). Moreover, increasing of pH values had a significant effect on compressive strength of the experimental groups (p<0.001). Conclusion: The compressive strength of NanoWMTA was significantly higher than WMTA and Bioaggregate; the more acidic the environmental pH, the lower was the compressive strength. Key words:Compressive strength, mineral trioxide aggregate, Nano. PMID:23722137

Design of a bioresorbable polymeric scaffold for osteoblast culture

NASA Astrophysics Data System (ADS)

Ditaranto, Vincent M., Jr.

Bioresorbable polymeric scaffolds were designed for the purpose of growing rat osteosarcoma cells (ROS 17/2.8) using the compression molding method. The material used in the construction of the scaffolds was a mixture of polycaprolactone (PCL), Hydroxyapatite (HA), Glycerin (GL) and salt (NaCl) for porosity. The concentration of the several materials utilized, was determined by volume. Past research at the University of Massachusetts Lowell (UML) has successfully utilized the compression molding method for the construction of scaffolds, but was unable to accomplish the goal of long term cell survival and complete cellular proliferation throughout a three dimensional scaffold. This research investigated various concentrations of the materials and molding temperatures used for the manufacture of scaffolds in order to improve the scaffold design and address those issues. The design of the scaffold using the compression molding process is detailed in the Method and Materials section of this thesis. The porogen (salt) used for porosity was suspected as a possible source of contamination causing cell apoptosis in past studies. This research addressed the issues for cell survival and proliferation throughout a three dimensional scaffold. The leaching of the salt was one major design modification. This research successfully used ultrasonic leaching in addition to the passive method. Prior to cell culture, the scaffolds were irradiated to 2.75 Mrad, with cobalt-60 gamma radionuclide. The tissue culture consisted of two trials: (1) cell culture in scaffolds cleaned with passive leaching; (2) cell culture with scaffolds cleaned with ultrasonic leaching. Cell survival and proliferation was accomplished only with the addition of ultrasonic leaching of the scaffolds. Analysis of the scaffolds included Scanning Electron Microscopy (SEM), Nikon light microscopy and x-ray mapping of the calcium, sodium and chloride ion distribution. The cells were analyzed by Environmental Scanning Electron Microscopy (ESEM) and Nikon light microscopy. The high magnification of ESEM up to 60,000 x revealed an unexpected discovery. The osteoblasts appeared to be remodeling the PCL scaffold shown in the last two figures of this research.

Choline chloride based ionic liquid analogues as tool for the fabrication of agar films with improved mechanical properties

USDA-ARS?s Scientific Manuscript database

In the present paper, we test the suitability of Choline-Cl/urea (DES-U) and Choline-Cl/glycerol (DES-G) eutectic mixtures at 1:2 molar ratios for the production of agar biodegradable films. A three-step process is proposed: pre-solubilization of polymer in DES followed by compression-molding and s...

Simulation Analysis and Performance Study of CoCrMo Porous Structure Manufactured by Selective Laser Melting

NASA Astrophysics Data System (ADS)

Guoqing, Zhang; Junxin, Li; Jin, Li; Chengguang, Zhang; Zefeng, Xiao

2018-04-01

To fabricate porous implants with improved biocompatibility and mechanical properties that are matched to their application using selective laser melting (SLM), flow within the mold and compressive properties and performance of the porous structures must be comprehensively studied. Parametric modeling was used to build 3D models of octahedron and hexahedron structures. Finite element analysis was used to evaluate the mold flow and compressive properties of the parametric porous structures. A DiMetal-100 SLM molding apparatus was used to manufacture the porous structures and the results evaluated by light microscopy. The results showed that parametric modeling can produce robust models. Square structures caused higher blood cell adhesion than cylindrical structures. "Vortex" flow in square structures resulted in chaotic distribution of blood elements, whereas they were mostly distributed around the connecting parts in the cylindrical structures. No significant difference in elastic moduli or compressive strength was observed in square and cylindrical porous structures of identical characteristics. Hexahedron, square and cylindrical porous structures had the same stress-strain properties. For octahedron porous structures, cylindrical structures had higher stress-strain properties. Using these modeling and molding results, an important basis for designing and the direct manufacture of fixed biological implants is provided.

Simulation Analysis and Performance Study of CoCrMo Porous Structure Manufactured by Selective Laser Melting

NASA Astrophysics Data System (ADS)

Guoqing, Zhang; Junxin, Li; Jin, Li; Chengguang, Zhang; Zefeng, Xiao

2018-05-01

To fabricate porous implants with improved biocompatibility and mechanical properties that are matched to their application using selective laser melting (SLM), flow within the mold and compressive properties and performance of the porous structures must be comprehensively studied. Parametric modeling was used to build 3D models of octahedron and hexahedron structures. Finite element analysis was used to evaluate the mold flow and compressive properties of the parametric porous structures. A DiMetal-100 SLM molding apparatus was used to manufacture the porous structures and the results evaluated by light microscopy. The results showed that parametric modeling can produce robust models. Square structures caused higher blood cell adhesion than cylindrical structures. "Vortex" flow in square structures resulted in chaotic distribution of blood elements, whereas they were mostly distributed around the connecting parts in the cylindrical structures. No significant difference in elastic moduli or compressive strength was observed in square and cylindrical porous structures of identical characteristics. Hexahedron, square and cylindrical porous structures had the same stress-strain properties. For octahedron porous structures, cylindrical structures had higher stress-strain properties. Using these modeling and molding results, an important basis for designing and the direct manufacture of fixed biological implants is provided.

On processing development for fabrication of fiber reinforced composite, part 2

NASA Technical Reports Server (NTRS)

Hou, Tan-Hung; Hou, Gene J. W.; Sheen, Jeen S.

1989-01-01

Fiber-reinforced composite laminates are used in many aerospace and automobile applications. The magnitudes and durations of the cure temperature and the cure pressure applied during the curing process have significant consequences for the performance of the finished product. The objective of this study is to exploit the potential of applying the optimization technique to the cure cycle design. Using the compression molding of a filled polyester sheet molding compound (SMC) as an example, a unified Computer Aided Design (CAD) methodology, consisting of three uncoupled modules, (i.e., optimization, analysis and sensitivity calculations), is developed to systematically generate optimal cure cycle designs. Various optimization formulations for the cure cycle design are investigated. The uniformities in the distributions of the temperature and the degree with those resulting from conventional isothermal processing conditions with pre-warmed platens. Recommendations with regards to further research in the computerization of the cure cycle design are also addressed.

40 CFR Table 4 to Subpart Wwww of... - Work Practice Standards

Code of Federal Regulations, 2010 CFR

2010-07-01

.... a new or existing closed molding operation using compression/injection molding uncover, unwrap or... new or existing cleaning operation not use cleaning solvents that contain HAP, except that styrene may... contacts resin. 3. a new or existing materials HAP-containing materials storage operation keep containers...

An in vitro study to compare the transverse strength of thermopressed and conventional compression-molded polymethylmethacrylate polymers.

PubMed

Raut, Anjana; Rao, Polsani Laxman; Vikas, B V J; Ravindranath, T; Paradkar, Archana; Malakondaiah, G

2013-01-01

Acrylic resins have been in the center stage of Prosthodontics for more than half a century. The flexural fatigue failure of denture base materials is the primary mode of clinical failure. Hence there is a need for superior physical and mechanical properties. This in vitro study compared the transverse strength of specimens of thermopressed injection-molded and conventional compression-molded polymethylmethacrylate polymers and examined the morphology and microstructure of fractured acrylic specimens. The following denture base resins were examined: Brecrystal (Thermopressed injection-molded, modified polymethylmethacrylate) and Pyrax (compression molded, control group). Specimens of each material were tested according to the American Society for Testing and Materials standard D790-03 for flexural strength testing of reinforced plastics and subsequently examined under SEM. The data was analyzed with Student unpaired t test. Flexural strength of Brecrystal (82.08 ± 1.27 MPa) was significantly higher than Pyrax (72.76 ± 0.97 MPa). The tested denture base materials fulfilled the requirements regarding flexural strength (>65 MPa). The scanning electron microscopy image of Brecrystal revealed a ductile fracture with crazing. The fracture pattern of control group specimens exhibited poorly defined crystallographic planes with a high degree of disorganization. Flexural strength of Brecrystal was significantly higher than the control group. Brecrystal showed a higher mean transverse strength value of 82.08 ± 1.27 MPa and a more homogenous pattern at microscopic level. Based on flexural strength properties and handling characteristics, Brecrystal may prove to be an useful alternative to conventional denture base resins.

Development and demonstration of manufacturing processes for fabricating graphite/LARC 160 polyimide structural elements

NASA Technical Reports Server (NTRS)

Frost, R. K.; Jones, J. S.; Dynes, P. J.; Wykes, D. H.

1981-01-01

The development and demonstration of manufacturing technologies for the structural application of Celion graphite/LARC-160 polyimide composite material is discussed. Process development and fabrication of demonstration components are discussed. Process development included establishing quality assurance of the basic composite material and processing, nondestructive inspection of fabricated components, developing processes for specific structural forms, and qualification of processes through mechanical testing. Demonstration components were fabricated. The demonstration components consisted of flat laminates, skin/stringer panels, honeycomb panels, chopped fiber compression moldings, and a technology demonstrator segment (TDS) representative of the space shuttle aft body flap.

Low cost damage tolerant composite fabrication

NASA Technical Reports Server (NTRS)

Palmer, R. J.; Freeman, W. T.

1988-01-01

The resin transfer molding (RTM) process applied to composite aircraft parts offers the potential for using low cost resin systems with dry graphite fabrics that can be significantly less expensive than prepreg tape fabricated components. Stitched graphite fabric composites have demonstrated compression after impact failure performance that equals or exceeds that of thermoplastic or tough thermoset matrix composites. This paper reviews methods developed to fabricate complex shape composite parts using stitched graphite fabrics to increase damage tolerance with RTM processes to reduce fabrication cost.

Test and analysis results for composite transport fuselage and wing structures

NASA Technical Reports Server (NTRS)

Deaton, Jerry W.; Kullerd, Susan M.; Madan, Ram C.; Chen, Victor L.

1992-01-01

Automated tow placement (ATP) and stitching of dry textile composite preforms followed by resin transfer molding (RTM) are being studied as cost effective manufacturing processes for obtaining damage tolerant fuselage and wing structures for transport aircraft. Data are presented to assess the damage tolerance of ATP and RTM fuselage elements with stitched-on stiffeners from compression tests of impacted three J-stiffened panels and from stiffener pull-off tests. Data are also presented to assess the damage tolerance of RTM wing elements which had stitched skin and stiffeners from impacted single stiffener and three blade stiffened compression tests and stiffener pull-off tests.

A Route for Polymer Nanocomposites with Engineered Electrical Conductivity and Percolation Threshold

PubMed Central

Kalaitzidou, Kyriaki; Fukushima, Hiroyuki; Drzal, Lawrence T.

2010-01-01

Polymer nanocomposites with engineered electrical properties can be made by tuning the fabrication method, processing conditions and filler’s geometric and physical properties. This work focuses on investigating the effect of filler’s geometry (aspect ratio and shape), intrinsic electrical conductivity, alignment and dispersion within the polymer, and polymer crystallinity, on the percolation threshold and electrical conductivity of polypropylene based nanocomposites. The conductive reinforcements used are exfoliated graphite nanoplatelets, carbon black, vapor grown carbon fibers and polyacrylonitrile carbon fibers. The composites are made using melt mixing followed by injection molding. A coating method is also employed to improve the nanofiller’s dispersion within the polymer and compression molding is used to alter the nanofiller’s alignment.

Taking Impressions of Hidden Cavity Walls

NASA Technical Reports Server (NTRS)

Burley, D.; Mayer, W.

1987-01-01

Lightweight, portable internal-molding device makes it possible to measure radii of, or examine contours of, passageways in hidden or complicated cavities. With device, measurements made in field, without returning assemblies to shop or laboratory for inspection. Molding head expands when compressed air applied. Inflatable tubes around head perform dual sealing and aligning function.

Low-cost conformable storage to maximize vehicle range

DOE Office of Scientific and Technical Information (OSTI.GOV)

Graham, R.P.

Liquefied petroleum gas (LPG) and compressed natural gas (CNG) are currently the leading fuel contenders for converting vehicles from gasoline and diesel to alternative fuels. Two factors that inhibit conversion are additional vehicle costs and reduced range compared to gasoline. In overcoming these barriers, a key element of the alternative fuel system becomes the storage tank for these pressurized fuels. Using cylindrical pressure vessels is the conventional approach, but they do not package well in the available vehicle volume. Thiokol Corporation has developed and is now producing a conformable (non-cylindrical) aluminum storage system for LPG vans. This system increases fuelmore » storage in a given rectangular envelope. The goal of this project was to develop the technology for a lower cost conformable tank made of injection-molded plastic. Much of the cost of the aluminum conformable tank is in the fabrication because several weld seams are required. The injection-molding process has the potential to greatly reduce the fabrication costs. The requirements of a pressurized fuel tank on a vehicle necessitate the proper combination of material properties. Material selection and tank design must be optimized for maximum internal volume and minimum material use to be competitive with other technologies. The material and the design must also facilitate the injection-molding process. Prototype tanks must be fabricated to reveal molding problems, prove solutions, and measure results. In production, efficient fabrication will be key to making these tanks cost competitive. The work accomplished during this project has demonstrated that conformable LPG tanks can be molded with thermoplastics. However, to achieve a competitive tank, improvements are needed in the effective material strength. If these improvements can be made, molded plastics should produce a lower cost tank that can store more LPG on a vehicle than conventional cylinders.« less

From micro- to nano-scale molding of metals : size effect during molding of single crystal Al with rectangular strip punches.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, K.; Meng, W. J.; Mei, F.

2011-02-01

A single crystal Al specimen was molded at room temperature with long, rectangular, strip diamond punches. Quantitative molding response curves were obtained at a series of punch widths, ranging from 5 {micro}m to 550 nm. A significant size effect was observed, manifesting itself in terms of significantly increasing characteristic molding pressure as the punch width decreases to 1.5 {micro}m and below. A detailed comparison of the present strip punch molding results was made with Berkovich pyramidal indentation on the same single crystal Al specimen. The comparison reveals distinctly different dependence of the characteristic pressure on corresponding characteristic length. The presentmore » results show the feasibility of micro-/nano-scale compression molding as a micro-/nano-fabrication technique, and offer an experimental test case for size-dependent plasticity theories.« less

Improvements in Fabrication of Sand/Binder Cores for Casting

NASA Technical Reports Server (NTRS)

Bakhitiyarov, Sayavur I.; Overfelt, Ruel A.; Adanur, Sabit

2005-01-01

Three improvements have been devised for the cold-box process, which is a special molding process used to make sand/binder cores for casting hollow metal parts. These improvements are: The use of fiber-reinforced composite binder materials (in contradistinction to the non-fiber-reinforced binders used heretofore), The substitution of a directed-vortex core-blowing subprocess for a prior core-blowing process that involved a movable gassing plate, and The use of filters made from filtration-grade fabrics to prevent clogging of vents. For reasons that exceed the scope of this article, most foundries have adopted the cold-box process for making cores for casting metals. However, this process is not widely known outside the metal-casting industry; therefore, a description of pertinent aspects of the cold-box process is prerequisite to a meaningful description of the aforementioned improvements. In the cold-box process as practiced heretofore, sand is first mixed with a phenolic resin (considered to be part 1 of a three-part binder) and an isocyanate resin (part 2 of the binder). Then by use of compressed air, the mixture is blown into a core box, which is a mold for forming the core. Next, an amine gas (part 3 of the binder) that acts as a catalyst for polymerization of parts 1 and 2 is blown through the core box. Alternatively, a liquid amine that vaporizes during polymerization can be incorporated into the sand/resin mixture. Once polymerization is complete, the amine gas is purged from the core box by use of compressed air. The finished core is then removed from the core box.

Materials to Engineer the Immune System

DTIC Science & Technology

2010-04-01

presentation of danger signals to regulate the ratio of distinct DC subtypes was next examined by immobilizing TLR-activating, polyethylenimine (PEI...compression molded. The resulting disc was allowed to equilibrate within a high-pressure CO2 environment, and a rapid reduction in pressure causes the...pressure CO2 process to foam macroporous PLG matrices incorporating tumor lysates. To incorporate CpG-ODNs into PLG scaffolds, we first con- densed CpG-ODN

Formability and mechanical properties of porous titanium produced by a moldless process.

PubMed

Naito, Yoshihito; Bae, Jiyoung; Tomotake, Yoritoki; Hamada, Kenichi; Asaoka, Kenzo; Ichikawa, Tetsuo

2013-08-01

Tailor-made porous titanium implants show great promise in both orthopedic and dental applications. However, traditional powder metallurgical processes require a high-cost mold, making them economically unviable for producing unique devices. In this study, a mixture of titanium powder and an inlay wax binder was developed for moldless forming and sintering. The formability of the mixture, the dimensional changes after sintering, and the physical and mechanical properties of the sintered porous titanium were evaluated. A 90:10 wt % mixture of Ti powder and wax binder was created manually at 70°C. After debindering, the specimen was sintered in Ar at 1100°C without any mold for 1, 5, and 10 h. The shrinkage, porosity, absorption ratio, bending and compressive strength, and elastic modulus were measured. The bending strength (135-356 MPa), compression strength (178-1226 MPa), and elastic modulus (24-54 GPa) increased with sintering time; the shrinkage also increased, whereas the porosity (from 37.1 to 29.7%) and absorption ratio decreased. The high formability of the binder/metal powder mixture presents a clear advantage for fabricating tailor-made bone and hard tissue substitution units. Moreover, the sintered compacts showed high strength and an elastic modulus comparable to that of cortical bone. Copyright © 2013 Wiley Periodicals, Inc.

A mass reduction effort of the electric and hybrid vehicle. [composite door panels

NASA Technical Reports Server (NTRS)

Freeman, R. B.; Jahnle, H. A.

1980-01-01

Weight reduction, cost competitiveness, and elimination of the intrusion beam resulted from the redesign and fabrication using composite materials of the door outer panel and intrusion beam from a Chevrolet Impala. The basis of the redesign involved replacing these two steel parts with a single compression molding using the unique approach of simultaneously curing a sheet molding compound outside panel with a continuous glass fiber intrusion strap. A weight reduction of nearly 11 pounds per door was achieved. Additional weight savings are possible by taking advantage of the elimination of the intrusion beam to design thinner door structures. The parts consolidation approach allows the composite structure to be cost competitive with the original steel design for both the lower production car models and for the near to midterm production vehicles using current state of the art composite production techniques. The design, prototype fabrication, costing, material, properties and compression molding production requirements are discussed.

Producing Zirconium Diboride Components with Complex, Near-Net Shape Geometries by Aqueous Room-Temperature Injection Molding

NASA Technical Reports Server (NTRS)

Wiesner, Valerie L.; Youngblood, Jeffrey; Trice, Rodney

2014-01-01

Room-temperature injection molding is proposed as a novel, low-cost and more energy efficient manufacturing process capable of forming complex-shaped zirconium diboride (ZrB2) parts. This innovative processing method utilized aqueous suspensions with high powder loading and a minimal amount (5 vol.) of water-soluble polyvinylpyrrolidone (PVP), which was used as a viscosity modifier. Rheological characterization was performed to evaluate the room-temperature flow properties of ZrB2-PVP suspensions. ZrB2 specimens were fabricated with high green body strength and were machinable prior to binder removal despite their low polymer content. After binder burnout and pressureless sintering, the bulk density and microstructure of specimens were characterized using Archimedes technique and scanning electron microscopy. X-Ray Diffraction was used to determine the phase compositions present in sintered specimens. Ultimate strength of sintered specimens will be determined using ASTM C1323-10 compressive C-ring test.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Weizhao; Zhang, Zixuan; Lu, Jie

Carbon fiber composites have received growing attention because of their high performance. One economic method to manufacturing the composite parts is the sequence of forming followed by the compression molding process. In this sequence, the preforming procedure forms the prepreg, which is the composite with the uncured resin, to the product geometry while the molding process cures the resin. Slip between different prepreg layers is observed in the preforming step and this paper reports a method to characterize the properties of the interaction between different prepreg layers, which is critical to predictive modeling and design optimization. An experimental setup wasmore » established to evaluate the interactions at various industrial production conditions. The experimental results were analyzed for an in-depth understanding about how the temperature, the relative sliding speed, and the fiber orientation affect the tangential interaction between two prepreg layers. The interaction factors measured from these experiments will be implemented in the computational preforming program.« less

Effect of volatile removal during molding on the properties of two phenolic-fiber composites

NASA Technical Reports Server (NTRS)

Price, H. L.; Lucy, M. H.

1974-01-01

A comparison has been made of the effect of three volatile-removing techniques during molding on the properties of phenolic-fiber composites. The first technique involved heating the molding compound from one side, initiating the volatile-producing reactions, and driving these volatiles through the compound toward the cooler side. The second technique involved the application of a vacuum to the molding cavity before and during the cure cycle. The third technique was a combination of the first two. These techniques were used in the compression molding of phenolic-asbestos and phenolic-glass composites. The effects of both the individual and combined techniques on the mechanical, thermal, and sorption properties of the composites are reported.

Processing and characterization of unidirectional thermoplastic nanocomposites

NASA Astrophysics Data System (ADS)

Narasimhan, Kameshwaran

The manufacture of continuous fibre-reinforced thermoplastic nanocomposites is discussed for the case of E-Glass reinforced polypropylene (PP) matrix and for E-Glass reinforced Polyamide-6 (Nylon-6), with and without dispersed nanoclay (montmorillonite) platelets. The E-Glass/PP nanocomposite was manufactured using pultrusion, whereas the E-Glass/Nylon-6 nanocomposite was manufactured using compression molding. Mechanical characterization of nanocomposites were performed and compared with traditional microcomposites. Compressive as well as shear strength of nanocomposites was improved by improving the yield strength of the surrounding matrix through the dispersion of nanoclay. Significant improvements were achieved in compressive strength and shear strength with relatively low nanoclay loadings. Initially, polypropylene with and without nanoclay were melt intercalated using a single-screw extruder and the pultruded nanocomposite was fabricated using extruded pre-impregnated (pre-preg) tapes. Compression tests were performed as mandated by ASTM guidelines. SEM and TEM characterization revealed presence of nanoclay in an intercalated and partially exfoliated morphology. Mechanical tests confirmed significant improvements in compressive strength (˜122% at 10% nanoclay loading) and shear strength (˜60% at 3% nanoclay loading) in modified pultruded E-Glass/PP nanocomposites in comparison with baseline properties. Uniaxial tensile tests showed a small increase in tensile strength (˜3.4%) with 3% nanoclay loading. Subsequently, E-Glass/Nylon-6 nanocomposite panels were manufactured by compression molding. Compression tests were performed according to IITRI guidelines, whereas short beam shear and uni-axial tensile tests were performed according to ASTM standards. Mechanical tests confirmed strength enhancement with nanoclay addition, with a significant improvement in compressive strength (50% at 4% nanoclay loading) and shear strength (˜36% at 4% nanoclay loading) when compared with the baseline E-Glass/Nylon-6. Uni-axial tensile tests resulted in a small increase in tensile strength (˜3.2%) with 4% nanoclay loading. Also, hygrothermal aging (50°C and 100% RH) of baseline and nanoclay modified (4%) E-Glass/Nylon-6 was studied. It was observed that the moisture diffusion process followed Fickian diffusion. E-Glass/Nylon-6 modified with 4% nanoclay loading showed improved barrier performance with a significant reduction (˜30%) in moisture uptake compared to baseline E-Glass/Nylon-6 composites. Significant improvement in mechanical properties was also observed in hygrothermally aged nanocomposite specimens when compared with the aged baseline composite.

Induction Consolidation of Thermoplastic Composites Using Smart Susceptors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matsen, Marc R

2012-06-14

This project has focused on the area of energy efficient consolidation and molding of fiber reinforced thermoplastic composite components as an energy efficient alternative to the conventional processing methods such as autoclave processing. The expanding application of composite materials in wind energy, automotive, and aerospace provides an attractive energy efficiency target for process development. The intent is to have this efficient processing along with the recyclable thermoplastic materials ready for large scale application before these high production volume levels are reached. Therefore, the process can be implemented in a timely manner to realize the maximum economic, energy, and environmental efficiencies.more » Under this project an increased understanding of the use of induction heating with smart susceptors applied to consolidation of thermoplastic has been achieved. This was done by the establishment of processing equipment and tooling and the subsequent demonstration of this fabrication technology by consolidating/molding of entry level components for each of the participating industrial segments, wind energy, aerospace, and automotive. This understanding adds to the nation's capability to affordably manufacture high quality lightweight high performance components from advanced recyclable composite materials in a lean and energy efficient manner. The use of induction heating with smart susceptors is a precisely controlled low energy method for the consolidation and molding of thermoplastic composites. The smart susceptor provides intrinsic thermal control based on the interaction with the magnetic field from the induction coil thereby producing highly repeatable processing. The low energy usage is enabled by the fact that only the smart susceptor surface of the tool is heated, not the entire tool. Therefore much less mass is heated resulting in significantly less required energy to consolidate/mold the desired composite components. This energy efficiency results in potential energy savings of {approx}75% as compared to autoclave processing in aerospace, {approx}63% as compared to compression molding in automotive, and {approx}42% energy savings as compared to convectively heated tools in wind energy. The ability to make parts in a rapid and controlled manner provides significant economic advantages for each of the industrial segments. These attributes were demonstrated during the processing of the demonstration components on this project.« less

PERFORMANCE ENHANCEMENT OF COMPRESSION MOLDED KENAF FIBER REINFORCED VINYL ESTER COMPOSITES THROUGH RESIN ADDITIVE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fifield, Leonard S.; Simmons, Kevin L.; Laddha, Sachin

2010-05-17

Plant-based bio-fiber has the potential to achieve weight and cost savings over glass fiber in automotive polymer composites if moisture stability and fiber-resin compatibility issues can be solved. This paper describes the compression molding of 50vol% 2 inch random nonwoven mat kenaf fiber vinyl ester composites with and without chemical resin additives intended to improve moisture stability and resin compatibility. The 2wt% addition of n-undecanoyl chloride or 10-undecenoyl chloride to the styrene-based resin prior to molding of the kenaf composites was observed to decrease the 24hr, 25oC moisture uptake of the molded panels by more than 50%. The tensile stiffnessmore » and flexural stiffness of the soaked panels containing these additives were seen to increase by more than 30% and 70%, respectively, relative to panels made with no additives. While ‘dry’ panel (50% relative humidity at 25oC) strengths did not significantly change in the presence of the additives, tensile strength was observed to increase by more than 40% and flexural strength more than doubled for the soaked panels.« less

Active bilayer films of thermoplastic starch and polycaprolactone obtained by compression molding.

PubMed

Ortega-Toro, Rodrigo; Morey, Iris; Talens, Pau; Chiralt, Amparo

2015-08-20

Bilayer films consisting of one layer of PCL with either one of thermoplastic starch (S) or one of thermoplastic starch with 5% PCL (S95) were obtained by compression molding. Before compression, aqueous solutions of ascorbic acid or potassium sorbate were sprayed onto the S or S95 layers in order to plasticize them and favor layer adhesion. S95 films formed bilayers with PCL with very good adhesion and good mechanical performance, especially when potassium sorbate was added at the interface. All bilayers enhanced their barrier properties to water vapour (up to 96% compared to net starch films) and oxygen (up to 99% compared to PCL pure). Bilayers consisting of PCL and starch containing 5% PCL, with potassium sorbate at the interface, showed the best mechanical and barrier properties and interfacial adhesion while having active properties, associated with the antimicrobial action of potassium sorbate. Copyright © 2015 Elsevier Ltd. All rights reserved.

Formulation and evaluation of controlled release antibiotic biodegradable implants for post operative site delivery.

PubMed

Mathur, Vijay; Mudnaik, Rajesh; Barde, Laxmikant; Roy, Arghya; Shivhare, Umesh; Bhusari, Kishore

2010-03-01

Biodegradable implants of ciprofloxacin hydrochloride for post operative site delivery were prepared using glyceryl monostearate and different concentrations of polyethylene glycol (PEG 6000), glycerol and Tween 80 as erosion enhancers by compression and molding technique. Formulations were subjected to in vitro drug release by the USP dissolution method, while promising formulations were subjected to in vitro drug release by the agar gel method and also to stability studies. It was observed that glyceryl monostearate formed hydrophobic matrix and delayed the drug delivery. Antibiotic release profile was controlled by using different combinations of erosion enhancers. The formulation prepared by the compression method showed more delayed release compared to formulations prepared by the molding method.

INTEGRATION OF COST MODELS AND PROCESS SIMULATION TOOLS FOR OPTIMUM COMPOSITE MANUFACTURING PROCESS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pack, Seongchan; Wilson, Daniel; Aitharaju, Venkat

Manufacturing cost of resin transfer molded composite parts is significantly influenced by the cycle time, which is strongly related to the time for both filling and curing of the resin in the mold. The time for filling can be optimized by various injection strategies, and by suitably reducing the length of the resin flow distance during the injection. The curing time can be reduced by the usage of faster curing resins, but it requires a high pressure injection equipment, which is capital intensive. Predictive manufacturing simulation tools that are being developed recently for composite materials are able to provide variousmore » scenarios of processing conditions virtually well in advance of manufacturing the parts. In the present study, we integrate the cost models with process simulation tools to study the influence of various parameters such as injection strategies, injection pressure, compression control to minimize high pressure injection, resin curing rate, and demold time on the manufacturing cost as affected by the annual part volume. A representative automotive component was selected for the study and the results are presented in this paper« less

Testing of molded high temperature plastic actuator road seals for use in advanced aircraft hydraulic systems

NASA Technical Reports Server (NTRS)

Waterman, A. W.; Huxford, R. L.; Nelson, W. G.

1976-01-01

Molded high temperature plastic first and second stage rod seal elements were evaluated in seal assemblies to determine performance characteristics. These characteristics were compared with the performance of machined seal elements. The 6.35 cm second stage Chevron seal assembly was tested using molded Chevrons fabricated from five molding materials. Impulse screening tests conducted over a range of 311 K to 478 K revealed thermal setting deficiencies in the aromatic polyimide molding materials. Seal elements fabricated from aromatic copolyester materials structurally failed during impulse cycle calibration. Endurance testing of 3.85 million cycles at 450 K using MIL-H-83283 fluid showed poorer seal performance with the unfilled aromatic polyimide material than had been attained with seals machined from Vespel SP-21 material. The 6.35 cm first stage step-cut compression loaded seal ring fabricated from copolyester injection molding material failed structurally during impulse cycle calibration. Molding of complex shape rod seals was shown to be a potentially controllable technique, but additional molding material property testing is recommended.

Effects of Moisture and Other Contaminants in Friction Composites

DTIC Science & Technology

1993-01-30

NC 126, (Cardolite Corporation, Newark, NJ), a cashew nut shell liquid modified phenolic resin. NC126 is different from a straight phenolic resin in...that there is an alkyl chain substituent in the meta position of the phenol. The resin is derived from cashew nut shell liquid and is a solid...crosslinked cashew resin and is often referred to as cashew particles. The friction materials were processed by compression molding at 160 °C and 1000 psi

Polyimide Composites from 'Salt-Like' Solution Precursors

NASA Technical Reports Server (NTRS)

Cano, Roberto J.; Hou, Tan H.; Weiser, Erik S.; SaintClair, Terry L.

2001-01-01

Four NASA Langley-developed polyimide matrix resins, LaRC(TM)-IA, LaRC(TM)-IAX, LaRC(TM)-8515 and LaRC(TM)-PETI-5, were produced via a 'saltlike' process developed by Unitika Ltd. The salt-like solutions (65% solids in NMP) were prepregged onto Hexcel IM7 carbon fiber using the NASA LaRC multipurpose tape machine. Process parameters were determined and composite panels fabricated. The temperature dependent volatile depletion rates, the thermal crystallization behavior and the resin rheology were characterized. Composite molding cycles were developed which consistently yielded well consolidated, void-free laminated parts. Composite mechanical properties such as the short beam shear strength; the longitudinal and transverse flexural strength and flexural modulus; the longitudinal compression strength and modulus; and the open hole compression strength and compression after impact strength were measured at room temperature and elevated temperatures. The processing characteristics and the composite mechanical properties of the four intermediate modulus carbon fiber/polyimide matrix composites were compared to existing data on the same polyimide resin systems and IM7 carbon fiber manufactured via poly(amide acid) solutions (30-35% solids in NMP). This work studies the effects of varying the synthetic route on the processing and mechanical properties of the polyimide composites.

Development and Evaluation of Stitched Sandwich Panels

NASA Technical Reports Server (NTRS)

Stanley, Larry E.; Adams, Daniel O.; Reeder, James R. (Technical Monitor)

2001-01-01

This study explored the feasibility and potential benefits provided by the addition of through-the-thickness reinforcement to sandwich structures. Through-the-thickness stitching is proposed to increase the interlaminar strength and damage tolerance of composite sandwich structures. A low-cost, out-of-autoclave processing method was developed to produce composite sandwich panels with carbon fiber face sheets, a closed-cell foam core, and through-the-thickness Kevlar stitching. The sandwich panels were stitched in a dry preform state, vacuum bagged, and infiltrated using Vacuum Assisted Resin Transfer Molding (VARTM) processing. For comparison purposes, unstitched sandwich panels were produced using the same materials and manufacturing methodology. Test panels were produced initially at the University of Utah and later at NASA Langley Research Center. Four types of mechanical tests were performed: flexural testing, flatwise tensile testing, core shear testing, and edgewise compression testing. Drop-weight impact testing followed by specimen sectioning was performed to characterize the damage resistance of stitched sandwich panels. Compression after impact (CAI) testing was performed to evaluate the damage tolerance of the sandwich panels. Results show significant increases in the flexural stiffness and strength, out-of-plane tensile strength, core shear strength, edgewise compression strength, and compression-after-impact strength of stitched sandwich structures.

Effect of Aspect Ratio on Electrical, Rheological and Glass Transition Properties of PC/MWCNT Nanocomposites.

PubMed

Cruz, Heidy; Son, Younggon

2018-02-01

Since the discovery of carbon nanotubes (CNT), significant research works have focused on the application of CNT as conductive filler to polymer nanocomposites which can be used in several fields such as electrostatic dissipation (ESD), electrostatic painting and electromagnetic interference shielding (EMI-shielding). However, the main challenge in the large-scale manufacturing of this technology is the poor electrical conductivity of polymer nanocomposites produced by injection molding process. This study aims to investigate the effect of CNT aspect ratio in improving the electrical conductivity of injection molded nanocomposites. In this work, three types of multiwall carbon nanotubes with different lengths were melt-mixed with polycarbonate in a twin screw extruder followed by injection and compression molding. Results show that nanocomposites with higher CNT aspect ratio exhibit higher electrical conductivity. Longer nanotubes form a stronger conductive network during secondary agglomeration which can withstand the high shear forces during injection molding. Higher melt viscosity and storage modulus were observed in nanocomposites with higher CNT aspect ratio which is attributed to the effective constriction of polymer chains by longer nanotubes. It was also found that Tg of the composites increased with nanotube aspect ratio and the addition of CNT causes degradation which leads to the general Tg depression of polycarbonate.

EMTA-NLA

DOE Office of Scientific and Technical Information (OSTI.GOV)

2009-10-14

EMTA-NLA is a computer program for analyzing the nonlinear stiffness, strength, and thermo-elastic properties of discontinuous fiber composite materials. Discontinuous fiber composites are chopped-fiber reinforced polymer materials that are formed by injection molding or compression molding techniques. The fibers tend to align during forming as the composite flows and fills the mold. EMTA-NLA can read the fiber orientation data from the molding software, Autodesk Moldflow Plastics Insight, and calculate the local material properties for accurately analyzing the warpage, stiffness, and strength of the as-formed composite part using the commercial NLA software. Therefore, EMTA-NLA is a unique assembly of mathematical algorithmsmore » that provide a one-of-a-kind composites constitutive model that links these two powerful commercial software packages.« less

High rate fabrication of compression molded components

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matsen, Marc R.; Negley, Mark A.; Dykstra, William C.

2016-04-19

A method for fabricating a thermoplastic composite component comprises inductively heating a thermoplastic pre-form with a first induction coil by inducing current to flow in susceptor wires disposed throughout the pre-form, inductively heating smart susceptors in a molding tool to a leveling temperature with a second induction coil by applying a high-strength magnetic field having a magnetic flux that passes through surfaces of the smart susceptors, shaping the magnetic flux that passes through surfaces of the smart susceptors to flow substantially parallel to a molding surface of the smart susceptors, placing the heated pre-form between the heated smart susceptors; andmore » applying molding pressure to the pre-form to form the composite component.« less

Characterization and Evaluation of Incorporation the Casting Sand in Mortar

NASA Astrophysics Data System (ADS)

Zanelato, E. B.; Azevedo, A. R. G.; Alexandre, J.; Xavier, C. G.; Monteiro, S. N.; Mendonça, T. A. O.

The process of casting metals and alloys occurs through the fusion of this metal and its subsequent casting into a mold with the dimensions and geometry close to the final piece. Most foundries use sand casting molds for making you. This work aims to characterize and evaluate the foundry sand to allow its use in segments of Civil Engineering, creating a viable destination for a residue is that discarded. The following characterization tests were performer: particle size, chemical analysis, X-ray Diffraction and Density Real grain. For the execution of the test specimens was used to 1:3 cement and sand, and the incorporation of 10% and 20% of the total mass replacing the sand, and the trace reference. The results show that best results in compression and bending tests were obtained by replacing 10 % of common sand for sand casting.

Experiments Related to the Fabrication of Carbon Fiber/AMB-21 Polyimide Composite Tubes Using the RTM Process

NASA Technical Reports Server (NTRS)

Exum, Daniel

1996-01-01

AMB-21 is a new polymer developed by Mr. Ray Vannucci, NASA, LeRC as a noncarcinogenic polyimide matrix which may be suitable for fabricating composite parts by the Resin Transfer Modeling (RTM) process. The polyimide for this project was prepared at the Center of Composite Materials Research at N.C. A&T State University because it is not currently an item of commerce. The RTM process is especially suitable for producing geometrically complex composite parts at a low cost. Because of the high melting point and very high viscosity at the time of processing, polyimides have not been extensively used in the RTM process. The process for preparing AMB-21 as well as the process for fabricating composite plates will be described. The basic fabrication process consists of injecting a solvent solution of AMP-21 into a carbon fiber preform, evaporating the solvent, imidizing the polyimide, and vacuum/compression modeling the impregnated preform. All the above molding steps are preformed in a specially designed RTM mold which will be described. The results of this process have been inconsistent. Where as some experiments have resulted in a reasonably sound panels, others have not. Further refinements of the process are required to establish a reliable process.

Mechanical and analytical screening of braided composites for transport fuselage applications

NASA Technical Reports Server (NTRS)

Fedro, Mark J.; Gunther, Christian; Ko, Frank K.

1991-01-01

The mechanics of materials progress in support of the goal of understanding the application of braided composites in a transport aircraft fuselage are summarized. Composites consisting of both 2-D and 3-D braid patterns are investigated. Both consolidation of commingled graphite/PEEK and resin transfer molding of graphite-epoxy braided composite processes are studied. Mechanical tests were used to examine unnotched tension, open hole tension, compression, compression after impact, in-plane shear, out-of-plane tension, bearing, and crippling. Analytical methods are also developed and applied to predict the stiffness and strengths of test specimens. A preliminary study using the test data and analytical results is performed to assess the applicability of braided composites to a commercial aircraft fuselage.

Mechanical properties and biocompatibility of melt processed, self-reinforced ultrahigh molecular weight polyethylene.

PubMed

Huang, Yan-Fei; Xu, Jia-Zhuang; Li, Jian-Shu; He, Ben-Xiang; Xu, Ling; Li, Zhong-Ming

2014-08-01

The low efficiency of fabrication of ultrahigh molecular weight polyethylene (UHMWPE)-based artificial knee joint implants is a bottleneck problem because of its extremely high melt viscosity. We prepared melt processable UHMWPE (MP-UHMWPE) by addition of 9.8 wt% ultralow molecular weight polyethylene (ULMWPE) as a flow accelerator. More importantly, an intense shear flow was applied during injection molding of MP-UHMWPE, which on one hand, promoted the self-diffusion of UHMWPE chains, thus effectively reducing the structural defects; on the other hand, increased the overall crystallinity and induced the formation of self-reinforcing superstructure, i.e., interlocked shish-kebabs and oriented lamellae. Aside from the good biocompatibility, and the superior fatigue and wear resistance to the compression-molded UHMWPE, the injection-molded MP-UHMWPE exhibits a noteworthy enhancement in tensile properties and impact strength, where the yield strength increases to 46.3 ± 4.4 MPa with an increment of 128.0%, the ultimate tensile strength and Young's modulus rise remarkably up to 65.5 ± 5.0 MPa and 1248.7 ± 45.3 MPa, respectively, and the impact strength reaches 90.6 kJ/m(2). These results suggested such melt processed and self-reinforced UHMWPE parts hold a great application promise for use of knee joint implants, particularly for younger and more active patients. Our work sets up a new method to fabricate high-performance UHMWPE implants by tailoring the superstructure during thermoplastic processing. Copyright © 2014 Elsevier Ltd. All rights reserved.

Making Plant-Support Structures From Waste Plant Fiber

NASA Technical Reports Server (NTRS)

Morrow, Robert C.; < oscjmocl. < attjew K/; {ertzbprm. A,amda; Ej (e. Cjad); Hunt, John

2006-01-01

Environmentally benign, biodegradable structures for supporting growing plants can be made in a process based on recycling of such waste plant fiber materials as wheat straw or of such derivative materials as paper and cardboard. Examples of structures that can be made in this way include plant plugs, pots, planter-lining mats, plant fences, and root and shoot barriers. No chemical binders are used in the process. First, the plant material is chopped into smaller particles. The particles are leached with water or steam to remove material that can inhibit plant growth, yielding a fibrous slurry. If the desired structures are plugs or sheets, then the slurry is formed into the desired shapes in a pulp molding subprocess. If the desired structures are root and shoot barriers, pots, or fences, then the slurry is compression-molded to the desired shapes in a heated press. The processed materials in these structures have properties similar to those of commercial pressboard, but unlike pressboard, these materials contain no additives. These structures have been found to withstand one growth cycle, even when wet

3D Printed Prisms with Tunable Dispersion for the THz Frequency Range

NASA Astrophysics Data System (ADS)

Busch, Stefan F.; Castro-Camus, Enrique; Beltran-Mejia, Felipe; Balzer, Jan C.; Koch, Martin

2018-04-01

Here, we present a 3D printed prism for THz waves made out of an artificial dielectric material in which the dispersion can be tuned by external compression. The artificial material consists of thin dielectric layers with variable air spacings which has been produced using a fused deposition molding process. The material properties are carefully characterized and the functionality of the prisms is in a good agreement with the underlying theory. These prisms are durable, lightweight, inexpensive, and easy to produce.

3D Printed Prisms with Tunable Dispersion for the THz Frequency Range

NASA Astrophysics Data System (ADS)

Busch, Stefan F.; Castro-Camus, Enrique; Beltran-Mejia, Felipe; Balzer, Jan C.; Koch, Martin

2018-06-01

Here, we present a 3D printed prism for THz waves made out of an artificial dielectric material in which the dispersion can be tuned by external compression. The artificial material consists of thin dielectric layers with variable air spacings which has been produced using a fused deposition molding process. The material properties are carefully characterized and the functionality of the prisms is in a good agreement with the underlying theory. These prisms are durable, lightweight, inexpensive, and easy to produce.

The Formation of Novel Thermoplastic Composites from Liquid Crystalline Polymers and Their Blends

DTIC Science & Technology

1991-07-01

melting point of the Vectra. This is due to the long relaxation time of the LCPs ccjzIed with the much higher viscosity of the matrix polymer. Ultem...the LCP reinforcing characteristics i.e. orientation and morphology can be retained upon post-processing provided that the melting point of the LCP is...isothermal compression molding and involves deforming the composites in a cold press after heating the blends at temperatures below the melting point of

The algorithm of verification of welding process for plastic pipes

NASA Astrophysics Data System (ADS)

Rzasinski, R.

2017-08-01

The study analyzes the process of butt welding of PE pipes in terms of proper selection of connector parameters. The process was oriented to the elements performed as a series of types of pipes. Polymeric materials commonly referred to as polymers or plastics, synthetic materials are produced from oil products in the polyreaction compounds of low molecular weight, called monomers. During the polyreactions monomers combine to build a macromolecule material monomer named with the prefix poly polypropylene, polyethylene or polyurethane, creating particles in solid state on the order of 0,2 to 0,4 mm. Finished products from polymers of virtually any shape and size are obtained by compression molding, injection molding, extrusion, laminating, centrifugal casting, etc. Weld can only be a thermoplastic that softens at an elevated temperature, and thus can be connected via a clamp. Depending on the source and method of supplying heat include the following welding processes: welding contact, radiant welding, friction welding, dielectric welding, ultrasonic welding. The analysis will be welding contact. In connection with the development of new generation of polyethylene, and the production of pipes with increasing dimensions (diameter, wall thickness) is important to select the correct process.

Fit of interim crowns fabricated using photopolymer-jetting 3D printing.

PubMed

Mai, Hang-Nga; Lee, Kyu-Bok; Lee, Du-Hyeong

2017-08-01

The fit of interim crowns fabricated using 3-dimensional (3D) printing is unknown. The purpose of this in vitro study was to evaluate the fit of interim crowns fabricated using photopolymer-jetting 3D printing and to compare it with that of milling and compression molding methods. Twelve study models were fabricated by making an impression of a metal master model of the mandibular first molar. On each study model, interim crowns (N=36) were fabricated using compression molding (molding group, n=12), milling (milling group, n=12), and 3D polymer-jetting methods. The crowns were prepared as follows: molding group, overimpression technique; milling group, a 5-axis dental milling machine; and polymer-jetting group using a 3D printer. The fit of interim crowns was evaluated in the proximal, marginal, internal axial, and internal occlusal regions by using the image-superimposition and silicone-replica techniques. The Mann-Whitney U test and Kruskal-Wallis tests were used to compare the results among groups (α=.05). Compared with the molding group, the milling and polymer-jetting groups showed more accurate results in the proximal and marginal regions (P<.001). In the axial regions, even though the mean discrepancy was smallest in the molding group, the data showed large deviations. In the occlusal region, the polymer-jetting group was the most accurate, and compared with the other groups, the milling group showed larger internal discrepancies (P<.001). Polymer-jet 3D printing significantly enhanced the fit of interim crowns, particularly in the occlusal region. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Processing, thermal and mechanical behaviour of PEI/MWCNT/carbon fiber nanostructured laminate

NASA Astrophysics Data System (ADS)

Santos, L. F. P.; Ribeiro, B.; Hein, L. R. O.; Botelho, E. C.; Costa, M. L.

2017-11-01

In this work, nanostructured composites of polyetherimide (PEI) with addition of functionalized multiwall carbon nanotube (MWCNT) were processed via solution mixing. After processing, these nanocomposites were evaluated by thermogravimetry (TGA), dynamic-mechanical analysis (DMA), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Subsequently, the nanocomposite was processed with carbon fibers by using hot compression molding. In order to evaluate interlaminar fracture strength, the processed laminates were mechanically evaluated by interlaminar shear strength (ILSS) and compression shear test (CST). Also, the Weibull distribution was employed to help in the statistical treatment of the data obtained from the mechanical tests. With regards to the fracture of the specimens, optical microscopy was used for the evaluation of the material. The addition of 1 wt% of MWCNT in the polymer matrix increased both thermal stability and viscoelastic behavior of the material. These improvements positively impacted the mechanical properties, generating a 16% and 58% increase in the short-beam strength and apparent interlaminar shear, respectively. In addition, it can be verified from morphological analysis of the fracture a change in the failure mode of the laminate by the incorporation of MWCNT. This behavior can be proven from CST test where there was no presence of the shear force by compression.

Lightweight and Compostable Fiberboard for the Military

DTIC Science & Technology

2012-08-01

individual sheets with compression molding methods. The second approach examined different biodegradable coatings for paper formation which enhanced wet...strength properties of paper based products. The third approach identified effective coated corrugated alternatives that exhibited comparable...fiberboard containers to different environmental conditions. Analysis of variance of compression data as a function of moisture, insert design and paper

Performance of resin transfer molded multiaxial warp knit composites

NASA Technical Reports Server (NTRS)

Dexter, H. Benson; Hasko, Gregory H.

1993-01-01

Composite materials that are subjected to complex loads have traditionally been fabricated with multidirectionally oriented prepreg tape materials. Some of the problems associated with this type of construction include low delamination resistance, poor out-of-plane strength, and labor intensive fabrication processes. Textile reinforced composites with through-the-thickness reinforcement have the potential to solve some of these problems. Recently, a relatively new class of noncrimp fabrics designated as multiaxial warp knits have been developed to minimize some of the high cost and damage tolerance concerns. Multiple stacks of warp knit fabrics can be knitted or stitched together to reduce layup labor cost. The through-the-thickness reinforcement can provide significant improvements in damage tolerance and out-of-plane strength. Multilayer knitted/stitched preforms, in conjunction with resin transfer molding (RTM), offer potential for significant cost savings in fabrication of primary aircraft structures. The objectives of this investigation were to conduct RTM processing studies and to characterize the mechanical behavior of composites reinforced with three multiaxial warp knit fabrics. The three fabrics investigated were produced by Hexcel and Milliken in the United States, and Saerbeck in Germany. Two resin systems, British Petroleum E9O5L and 3M PR 500, were characterized for RTM processing. The performance of Hexcel and Milliken quasi-isotropic knitted fabrics are compared to conventional prepreg tape laminates. The performance of the Saerbeck fabric is compared to uniweave wing skin layups being investigated by Douglas Aircraft Company in the NASA Advanced Composites Technology (ACT) program. Tests conducted include tension, open hole tension, compression, open hole compression, and compression after impact. The effects of fabric defects, such as misaligned fibers and gaps between tows, on material performance are also discussed. Estimated material and labor cost savings are projected for the Saerbeck fabric as compared to uniweave fabric currently being used by Douglas in the NASA ACT wing development program.

Structure and Compressive Properties of Invar-Cenosphere Syntactic Foams.

PubMed

Luong, Dung; Lehmhus, Dirk; Gupta, Nikhil; Weise, Joerg; Bayoumi, Mohamed

2016-02-18

The present study investigates the mechanical performance of syntactic foams produced by means of the metal powder injection molding process having an Invar (FeNi36) matrix and including cenospheres as hollow particles at weight fractions (wt.%) of 5 and 10, respectively, corresponding to approximately 41.6 and 60.0 vol.% in relation to the metal content and at 0.6 g/cm³ hollow particle density. The synthesis process results in survival of cenospheres and provides low density syntactic foams. The microstructure of the materials is investigated as well as the mechanical performance under quasi-static and high strain rate compressive loads. The compressive stress-strain curves of syntactic foams reveal a continuous strain hardening behavior in the plastic region, followed by a densification region. The results reveal a strain rate sensitivity in cenosphere-based Invar matrix syntactic foams. Differences in properties between cenosphere- and glass microsphere-based materials are discussed in relation to the findings of microstructural investigations. Cenospheres present a viable choice as filler material in iron-based syntactic foams due to their higher thermal stability compared to glass microspheres.

Moisture and temperature influence on mechanical behavior of PPS/buckypapers carbon fiber laminates

NASA Astrophysics Data System (ADS)

Rojas, J. A.; Santos, L. F. P.; Costa, M. L.; Ribeiro, B.; Botelho, E. C.

2017-07-01

In this work, multiwall carbon nanotubes (MWCNT) were dispersed in water with the assistance of water based surfactant and then sonicated in order to obtain a very well dispersed solution. The suspension was filtrate under vaccum conditions, generating a thin film called buckypapers (BP). Poly (phenylene sulphide) (PPS) reinforced carbon fiber (CF) and PPS reinforced CF/BP composites were manufactured through hot compression molding technique. Subsequently the samples were exposed to extreme humidity (90% of moisture) combined with high temperature (80 °C). The mechanical properties of the laminates were evaluated by dynamic mechanical analysis, compression shear test, interlaminar shear strength and impulse excitation of vibration. Volume fraction of pores were 10.93% for PPS/CF and 16.18% for PPS/BP/CF, indicating that the hot compression molding parameters employed in this investigation (1.4 MPa, 5 min and 330 °C) affected both the consolidation quality of the composites and the mechanical properties of the final laminates.

Occupational exposure to styrene in the fibreglass reinforced plastic industry: comparison between two different manufacturing processes.

PubMed

Tranfo, Giovanna; Gherardi, Monica; Paci, E; Gatto, Mariapia; Gordiani, A; Caporossi, Lidia; Capanna, Silvia; Sisto, Renata; Papaleo, B; Fiumalbi, Carla; Garofani, Patrizia

2012-01-01

Styrene is used in manufacturing fiberglass reinforced plastics: and occupational exposure was related to neurotoxicology and genotoxicity. The sum of the metabolites mandelic and phenylglyoxylic acids is the ACGIH biomarker for occupational exposure with a BEI of 400 mg/g of creatinine in end shift urine corresponding to a airborne styrene concentration of 85 mg/m3. There are two main molding processes, open and closed, the last more effective at controlling worker's styrene exposure. To compare the open molding process to the compression of fiber reinforced resin foils, a kind of closed molding, monitoring the styrene exposure of workers in two production sites (A and B). Environmental Monitoring was carried out by Radiello samplers and Biological Monitoring by means of the determination of MA and PGA with HPLC/MS/MS in 10 workers at Site A and 14 at Site B. The median values for styrene exposure resulted 31.1 mg/m3 for Site A and 24.4 mg/m for Site B, while the medians for the sum of the two metabolites in the end shift urine were 86.7 e 33.8 mg/g creatinine respectively. There is a significant linear correlation between personal styrene exposure and the excretion of styrene metabolites (R = 0.74). As expected the exposure markers of the workers of the two production sites resulted higher in the open process. The analytical results of both environmental and biological monitoring were all below the occupational exposure limits, confirming the efficacy of the protective devices.

The Influence of Multiple Nested Layer Waviness on the Compression Strength of Double Nested Wave Formations in a Carbon Fiber Composite Laminate

NASA Astrophysics Data System (ADS)

Khan, Z. M.; Adams, D. O.; Anas, S.

2016-01-01

As advanced composite materials having superior physical and mechanical properties are being developed, the optimization of their processing techniques is eagerly sought. One of the most common defects arising during processing of structural composites is layer waviness. The layer waviness is more pronounced in thick-section flat and cylindrical laminates, which are extensively used in large wind turbine blades, submersibles, and space platforms. The layer waviness undulates the entire layer of a multidirectional laminate in the throughthe-thickness direction, leading to a gross deterioration of its compressive strength. This research investigates the influence of multiple layer waviness in a double nest formation on the compression strength of a composite laminate. Different wave fractions of wavy 0° layers were fabricated in an IM/8551-7 carbon-epoxy composite laminate on a steel mold by using a single-step fabrication procedure. The test laminates were cured on a heated press according to the specific curing cycle of epoxy. Their static compression testing was performed using a NASA short block compression fixture on an MTS servohydraulic machine. The purpose of these tests was to determine the effects of multiple layer wave regions on the compression strength of the composite laminate. The experimental and analytical results obtained revealed that the reduction in the compression strength of composite laminate was constant after the fraction of the wavy 0° layers exceeded 35%. This analysis indicated that the percentage of the 0° wavy layer may be used to estimate the reduction in the compression strength of a double nested wave formation in a composite laminate.

Importance of Tensile Strength on the Shear Behavior of Discontinuities

NASA Astrophysics Data System (ADS)

Ghazvinian, A. H.; Azinfar, M. J.; Geranmayeh Vaneghi, R.

2012-05-01

In this study, the shear behavior of discontinuities possessing two different rock wall types with distinct separate compressive strengths was investigated. The designed profiles consisted of regular artificial joints molded by five types of plaster mortars, each representing a distinct uniaxial compressive strength. The compressive strengths of plaster specimens ranged from 5.9 to 19.5 MPa. These specimens were molded considering a regular triangular asperity profile and were designed so as to achieve joint walls with different strength material combinations. The results showed that the shear behavior of discontinuities possessing different joint wall compressive strengths (DDJCS) tested under constant normal load (CNL) conditions is the same as those possessing identical joint wall strengths, but the shear strength of DDJCS is governed by minor joint wall compressive strength. In addition, it was measured that the predicted values obtained by Barton's empirical criterion are greater than the experimental results. The finding indicates that there is a correlation between the joint roughness coefficient (JRC), normal stress, and mechanical strength. It was observed that the mode of failure of asperities is either pure tensile, pure shear, or a combination of both. Therefore, Barton's strength criterion, which considers the compressive strength of joint walls, was modified by substituting the compressive strength with the tensile strength. The validity of the modified criterion was examined by the comparison of the predicted shear values with the laboratory shear test results reported by Grasselli (Ph.D. thesis n.2404, Civil Engineering Department, EPFL, Lausanne, Switzerland, 2001). These comparisons infer that the modified criterion can predict the shear strength of joints more precisely.

Novel technique for fabrication of multi-layered microcoils in microelectromechanical systems (MEMS) applications

NASA Astrophysics Data System (ADS)

Chang, Hung-Pin; Qian, Jiangyuan; Bachman, Mark; Congdon, Philip; Li, Guann-pyng

2002-07-01

A novel planarization technique, compressive molding planarization (CMP) is developed for implementation of a multi-layered micro coil device. Applying CMP and other micromachining techniques, a multi-layered micro coil device has been designed and fabricated, and its use in the magnetic micro actuators for hard disk drive applications has been demonstrated, showing that it can produce milli-Newton of magnetic force suitable for driving a micro actuator. The novel CMP technique can be equally applicable in other MEMS devices fabrication to ease the process integration for the complicated structure.

Durable, Low-Surface-Energy Treatments

NASA Technical Reports Server (NTRS)

Willis, Paul B.; Mcelroy, Paul M.; Hickey, Gregory S.

1992-01-01

Chemical treatment for creation of durable, low-surface-energy coatings for glass, ceramics and other protonated surfaces easily applied, and creates very thin semipermanent film with extremely low surface tension. Exhibits excellent stability; surfaces retreated if coating becomes damaged or eroded. Uses include water-repellent surfaces, oil-repellent surfaces, antimigration barriers, corrosion barriers, mold-release agents, and self-cleaning surfaces. Film resists wetting by water, alcohols, hydrocarbon solvents, and silicone oil. Has moderate resistance to abrasion, such as rubbing with cloths, and compression molding to polymers and composite materials.

Fatigue-propagation du melange polymere polystyrene/polyethylene

NASA Astrophysics Data System (ADS)

Bureau, Martin N.

The interrelations between the morphology of PS/HDPE and PS/SEBS/HDPE immiscible polymer blends and their mechanical behavior, namely in monotonic loading and in cyclic loading, were studied. As predicted by theory, high shear rates encountered during extrusion blending led to efficient minor phase emulsification in PS/HDPE blends for which the viscosity ratio approaches unity. Consequently, the emulsifying effect of an SEBS triblock copolymer employed as a compatibilizer was found to be negligible. In subsequent molding process, disintegration, shape relaxation and coarsening of the minor phase domains were responsible for the morphological evolution of the blends. In the compression molding process, morphological observations showed that the rate of minor phase coarsening followed the predictions of the Ostwald ripening theory, in agreement with the rheological analysis. In the injection molding process, minor phase coarsening was attributed to shear coalescence. The fatigue crack propagation behavior of injection-molded specimens of pure PS as well as of 95/5, 85/15 and 70/30 PS/HDPE blends and of 95/(0.5/4.5), 85/(1.5/13.5) and 70/(3/27) PS/(SEBS/HDPE) blends was then studied. The fatigue fracture surface features of specimens of pure PS as well as of PS/HDPE and PS/SEBS/HDPE blends were analyzed in detail in order to interpret their fatigue crack propagation behavior. In pure PS specimens, discontinuous growth bands, associated with the fracture of crazes in the plastic zone, formed at low fatigue crack growth rates, large dimple-like features at intermediate fatigue crack growth rates and fatigue striations at high fatigue crack growth rates. The fracture toughness of injection-molded specimens of pure PS as well as of 95/5, 85/15 and 70/30 PS/HDPE blends and of 95/(0.5/4.5) PS/(SEBS/HDPE), 85/(1.5/13.5) and 70/(3/27) PS/(SEBS/HDPE) was finally studied. The results showed that the addition of HDPE to PS led to a reduction of the fracture toughness KQ following ASTM E-399 when compared to that of pure PS. This effect was attributed to the very fine minor phase morphology of the blends obtained after extrusion blending and injection molding. (Abstract shortened by UMI.)

Comparison of The Dimensional Stability of Kel-F 81 and Neoflon CTFE M400H Polychlorotrifluoroethylenes Used in Valve Seat Application

NASA Technical Reports Server (NTRS)

Waller, Jess M.; Beeson, Harold D.; Newton, Barry E.; Fries, Joseph (Technical Monitor)

2000-01-01

The dimensional stability of polychlorotrifluoroethylene (PCTFE) valve seats used in oxygen regulator applications was determined by thermomechanical analysis (TMA). Two traceable grades of PCTFE were tested; Kel-F 81 and Neoflon CTFE M400H. For these particular resins, the effect of percent crystallinity, zero strength time (ZST) molecular weight, resin grade, process history (compression-molded versus extruded) on the dimensional stability and annealing behavior was determined. In addition to the traceable Kel-F 81 and Neoflon CTFE M400H grades, actual PCI'PH valve seats of differing geometry and design were tested by TMA. The PCTFE valve seats were of unspecified resin grade, although certain inferences about the grade could be drawn based on knowledge of the valve seat fabrication date. Results consistently revealed dimensional instability of varying magnitude at temperatures ranging from 40 to 70 degrees Celsius. Furthermore, some of the pre- 1 995 seats appeared to be more dimensionally stable than those fabricated after 1995. The TMA results are discussed in the context of several proposed ignition mechanisms; namely, particle impact, presence of contaminant oils and fibers, and localized heating by flow friction and/or resonance. The effect of metal constraint on the dimensional stability of PCTFE is also discussed. Finally, the effect of percent crystallinity, ZST molecular weight, resin grade, process history (compression-molded versus extruded) on the AIT, delta Hc and impact sensitivity of various types of Neoflon CTFE M400H was determined using Kel-F 81 as a control. Results show that the AIT, delta Hc and impact sensitivity were essentially independent of Neoflon CTFE process history and structure.

Test and analysis results for composite transport fuselage and wing structures

NASA Technical Reports Server (NTRS)

Deaton, Jerry W.; Kullerd, Susan M.; Madan, Ram C.; Chen, Victor L.

1992-01-01

Automated tow placement (ATP) and stitching of dry textile composite preforms followed by resin transfer molding (RTM) are being investigated by researchers at NASA LaRC and Douglas Aircraft Company as cost-effective manufacturing processes for obtaining damage tolerant fuselage and wing structures for transport aircraft. The Douglas work is being performed under a NASA contract entitled 'Innovative Composites Aircraft Primary Structures (ICAPS)'. Data are presented in this paper to assess the damage tolerance of ATP and RTM fuselage elements with stitched-on stiffeners from compression tests of impacted three-J-stiffened panels and from stiffener pull-off tests. Data are also presented to assess the damage tolerance of RTM wing elements which had stitched skin and stiffeners from impacted single stiffener and three blade-stiffened compression tests and stiffener pull-off tests.

Development of stitching reinforcement for transport wing panels

NASA Technical Reports Server (NTRS)

Palmer, Raymond J.; Dow, Marvin B.; Smith, Donald L.

1991-01-01

The NASA Advanced Composites Technology (ACT) program has the objective of providing the technology required to obtain the full benefit of weight savings and performance improvements offered by composite primary aircraft structures. Achieving the objective is dependent upon developing composite materials and structures which are damage tolerant and economical to manufacture. Researchers are investigating stitching reinforcement combined with resin transfer molding to produce materials meeting the ACT program objective. Research is aimed at materials, processes, and structural concepts for application in both transport wings and fuselages, but the emphasis to date has been on wing panels. Empirical guidelines are being established for stitching reinforcement in structures designed for heavy loads. Results are presented from evaluation tests investigating stitching types, threads, and density (penetrations per square inch). Tension strength, compression strength, and compression after impact data are reported.

Energy Absorption in Chopped Carbon Fiber Compression Molded Composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Starbuck, J.M.

2001-07-20

In passenger vehicles the ability to absorb energy due to impact and be survivable for the occupant is called the ''crashworthiness'' of the structure. To identify and quantify the energy absorbing mechanisms in candidate automotive composite materials, test methodologies were developed for conducting progressive crush tests on composite plate specimens. The test method development and experimental set-up focused on isolating the damage modes associated with the frond formation that occurs in dynamic testing of composite tubes. Quasi-static progressive crush tests were performed on composite plates manufactured from chopped carbon fiber with an epoxy resin system using compression molding techniques. Themore » carbon fiber was Toray T700 and the epoxy resin was YLA RS-35. The effect of various material and test parameters on energy absorption was evaluated by varying the following parameters during testing: fiber volume fraction, fiber length, fiber tow size, specimen width, profile radius, and profile constraint condition. It was demonstrated during testing that the use of a roller constraint directed the crushing process and the load deflection curves were similar to progressive crushing of tubes. Of all the parameters evaluated, the fiber length appeared to be the most critical material parameter, with shorter fibers having a higher specific energy absorption than longer fibers. The combination of material parameters that yielded the highest energy absorbing material was identified.« less

Colloidal isopressing: A new shaping method for ceramic suspensions

NASA Astrophysics Data System (ADS)

Yu, Benjamin Christopher

Colloidal Isopressing is a new processing method for shaping compacts from particulate suspensions. The study of interparticle interactions within a suspension, and their effect on the overall slurry behavior, has led to the prior discovery of a plastic-to-brittle transition in powder compacts formed by pressure filtration. Colloidal Isopressing utilizes this pressure dependent behavior for slurries with a short-range repulsive potential to rapidly transform plastic consolidated bodies into more complex shapes. The first results are presented for aqueous alumina suspensions where electrostatic double layer repulsion is compressed to short interparticle separations by the addition of ammonium chloride. Consolidation at low pressures produces a high relative density slurry that is plastic and can be extruded into a rubber mold. The application of an hydrostatic pressure forces a small amount of liquid into a porous portion of the mold and pushes particles together into a rigid network. As the pressure is released, the newly formed powder compact will partially separate from the lower modulus rubber mold. The body can then be ejected from the mold, dried, and densified to produce the final ceramic component. Colloidal Isopressing has been successfully modeled as a special case of consolidation via pressure filtration. Theoretical analyses have accurately predicted the time required for the rapid transformation from plastic slurry to elastic powder compact. The effects of slurry composition on processing were studied. The electrolyte concentration, powder particle size, slurry pH, and polymer concentration were shown to alter the flow behavior of filter pressed and liquefied compacts. As the free volume of liquid decreased and/or the relative attraction between particles increased, the concentrated slurry became more difficult to process. Finally, drying of compacts formed by Colloidal Isopressing did not result in any shrinkage during drying, thus allowing for very rapid heating rates to be used. In fact, the drying, burnout, and densification could be combined into one step, with final densities approaching the theoretical limit.

Biopolymer foams - Relationship between material characteristics and foaming behavior of cellulose based foams

NASA Astrophysics Data System (ADS)

Rapp, F.; Schneider, A.; Elsner, P.

2014-05-01

Biopolymers are becoming increasingly important to both industry and consumers. With regard to waste management, CO2 balance and the conservation of petrochemical resources, increasing efforts are being made to replace standard plastics with bio-based polymers. Nowadays biopolymers can be built for example of cellulose, lactic acid, starch, lignin or bio mass. The paper will present material properties of selected cellulose based polymers (cellulose propionate [CP], cellulose acetate butyrate [CAB]) and corresponding processing conditions for particle foams as well as characterization of produced parts. Special focus is given to the raw material properties by analyzing thermal behavior (differential scanning calorimetry), melt strength (Rheotens test) and molecular weight distribution (gel-permeation chromatography). These results will be correlated with the foaming behavior in a continuous extrusion process with physical blowing agents and underwater pelletizer. Process set-up regarding particle foam technology, including extrusion foaming and pre-foaming, will be shown. The characteristics of the resulting foam beads will be analyzed regarding part density, cell morphology and geometry. The molded parts will be tested on thermal conductivity as well as compression behavior (E-modulus, compression strength).

High Pressure Compression-Molding of α-Cellulose and Effects of Operating Conditions.

PubMed

Pintiaux, Thibaud; Viet, David; Vandenbossche, Virginie; Rigal, Luc; Rouilly, Antoine

2013-05-30

Commercial α-cellulose was compression-molded to produce 1A dog-bone specimens under various operating conditions without any additive. The resulting agromaterials exhibited a smooth, plastic-like surface, and constituted a suitable target as replacement for plastic materials. Tensile and three-points bending tests were conducted according to ISO standards related to the evaluation of plastic materials. The specimens had strengths comparable to classical petroleum-based thermoplastics. They also exhibited high moduli, which is characteristic of brittle materials. A higher temperature and higher pressure rate produced specimens with higher mechanical properties while low moisture content produced weaker specimens. Generally, the strong specimen had higher specific gravity and lower moisture content. However, some parameters did not follow the general trend e.g., thinner specimen showed much higher Young's Modulus, although their specific gravity and moisture content remained similar to control, revealing a marked skin-effect which was confirmed by SEM observations.

Effect of fiber orientation on tensile and impact properties of Zalacca Midrib fiber-HDPE composites by compression molding

NASA Astrophysics Data System (ADS)

Lasikun, Ariawan, Dody; Surojo, Eko; Triyono, Joko

2018-02-01

The research aims to investigate the fiber orientation effect on the tensile and impact properties of zalacca midrib fiber /HDPE composites. The composites were produced by compression molding with pressing temperature at 150°C, pressing pressure at 50 bar, and holding time of 25 minutes. The fiber orientations applied in composites were 0°, 15°, 30°, 45°, 60°, 75°, and 90°, at 10% fiber volume fraction. The samples were evaluated by using: Tensile test and Izod impact test according to ASTM D638 and ASTM D5941, respectively. The result of experiments indicate that the orientation of zalacca midrib fiber influences the characteristics of HDPE composite-zalacca midrib fiber. The composite mechanical strength decline with the increase of orientation fibers from 0° to 90°. The composite failure mode of composites are observed by Scanning Electron Microscope (SEM).

High Pressure Compression-Molding of α-Cellulose and Effects of Operating Conditions

PubMed Central

Pintiaux, Thibaud; Viet, David; Vandenbossche, Virginie; Rigal, Luc; Rouilly, Antoine

2013-01-01

Commercial α-cellulose was compression-molded to produce 1A dog-bone specimens under various operating conditions without any additive. The resulting agromaterials exhibited a smooth, plastic-like surface, and constituted a suitable target as replacement for plastic materials. Tensile and three-points bending tests were conducted according to ISO standards related to the evaluation of plastic materials. The specimens had strengths comparable to classical petroleum-based thermoplastics. They also exhibited high moduli, which is characteristic of brittle materials. A higher temperature and higher pressure rate produced specimens with higher mechanical properties while low moisture content produced weaker specimens. Generally, the strong specimen had higher specific gravity and lower moisture content. However, some parameters did not follow the general trend e.g., thinner specimen showed much higher Young’s Modulus, although their specific gravity and moisture content remained similar to control, revealing a marked skin-effect which was confirmed by SEM observations. PMID:28809271

Dimensional change in complete dentures fabricated by injection molding and microwave processing.

PubMed

Keenan, Phillip L J; Radford, David R; Clark, Robert K F

2003-01-01

Acrylic resin complete dentures undergo dimensional changes during polymerization. Techniques with injection molding and polymerization and microwave polymerization are reported to reduce these changes and thereby improve clinical fit. These dimensional changes need to be quantified. The purpose of this study was to compare differences in dimensional changes of simulated maxillary complete dentures during polymerization and storage in water after injection molding and conventional polymerization, or microwave polymerization against a control of conventionally packed and polymerized simulated maxillary complete dentures. Forty identical maxillary denture bases were prepared in dental wax with anatomic teeth. They were invested and the wax eliminated from the molds. Ten specimens each were randomly assigned to 1 of 4 groups. Group 1 was compression molded and conventionally polymerized; group 2 was injection molded and conventionally polymerized (Success); group 3 was injection molded and microwave polymerized (Acron MC); and group 4 was injection molded and microwave polymerized (Microbase). Intermolar width and changes in vertical dimension of occlusion, were determined after polymerization and after storage in water for 28 days. Measurements in triplicate were made between points scribed on the second molar teeth with a traveling microscope (accurate to 0.005 mm). Vertical dimension of occlusion was measured between points scribed on the upper and lower members of an articulator by use of an internal micrometer (accurate to 0.05 mm). Data were analyzed by use of a 1-way analysis of variance with Tukey post-hoc contrasts (P <.05). Polymerization contractions (intermolar widths) for each group were: group 1, -0.24%; group 2, -0.27%; group 3, -0.35%; and group 4, -0.37%. The Microbase specimens had greater shrinkage than conventionally polymerized specimens, but there were no significant differences between the groups. All injection methods had less postpolymerization increase in vertical dimension of occlusion (0.63 to 0.41 mm) than the conventional Trevalon control (0.74 mm), but only group 4 was significantly different (P<.004). After storage in water for 28 days, all specimens increased in vertical dimension of occlusion (0.10% to 0.16%) from polymerization techniques, but there were no significant differences between groups. Within the limitations of this study, injection molding resulted in a slightly less increase of vertical dimension of occlusion than conventional polymerization techniques, the difference being significant for Microbase compared with the conventional Trevalon control.

Evaluation of Ceramic Honeycomb Core Compression Behavior at Room Temperature

NASA Technical Reports Server (NTRS)

Bird, Richard K.; Lapointe, Thomas S.

2013-01-01

Room temperature flatwise compression tests were conducted on two varieties of ceramic honeycomb core specimens that have potential for high-temperature structural applications. One set of specimens was fabricated using strips of a commercially-available thin-gage "ceramic paper" sheet molded into a hexagonal core configuration. The other set was fabricated by machining honeycomb core directly from a commercially available rigid insulation tile material. This paper summarizes the results from these tests.

Effects of 401’. Phosphoric Acid Etch on the Compressive Strength of Biodentine

DTIC Science & Technology

2016-06-10

specification No. 96 for water based cements . Specimens were prepared using stainless steel cylindrical split molds with the internal dimension of 4.0...determined according to ISO 9917:2010 and ADA specification No. 96 for water based cements . Specimens were prepared using stainless steel ...Copyright Statement. ……………………………………………………………….. 26   iv   List of Figures Figure 1. Stainless Steel Cylindrical Split Molds

Effecting aging time of epoxy molding compound to molding process for integrated circuit packaging

NASA Astrophysics Data System (ADS)

Tachapitunsuk, Jirayu; Ugsornrat, Kessararat; Srisuwitthanon, Warayoot; Thonglor, Panakamon

2017-09-01

This research studied about effecting aging time of epoxy molding compound (EMC) that effect to reliability performance of integrated circuit (IC) package in molding process. Molding process is so important of IC packaging process for protecting IC chip (or die) from temperature and humidity environment using encapsulated EMC. For general molding process, EMC are stored in the frozen at 5°C and left at room temperature at 25 °C for aging time on self before molding of die onto lead frame is 24 hours. The aging time effect to reliability performance of IC package due to different temperature and humidity inside the package. In experiment, aging time of EMC were varied from 0 to 24 hours for molding process of SOIC-8L packages. For analysis, these packages were tested by x-ray and scanning acoustic microscope to analyze properties of EMC with an aging time and also analyzed delamination, internal void, and wire sweep inside the packages with different aging time. The results revealed that different aging time of EMC effect to properties and reliability performance of molding process.

Multiscale finite element modeling of sheet molding compound (SMC) composite structure based on stochastic mesostructure reconstruction

DOE PAGES

Chen, Zhangxing; Huang, Tianyu; Shao, Yimin; ...

2018-03-15

Predicting the mechanical behavior of the chopped carbon fiber Sheet Molding Compound (SMC) due to spatial variations in local material properties is critical for the structural performance analysis but is computationally challenging. Such spatial variations are induced by the material flow in the compression molding process. In this work, a new multiscale SMC modeling framework and the associated computational techniques are developed to provide accurate and efficient predictions of SMC mechanical performance. The proposed multiscale modeling framework contains three modules. First, a stochastic algorithm for 3D chip-packing reconstruction is developed to efficiently generate the SMC mesoscale Representative Volume Element (RVE)more » model for Finite Element Analysis (FEA). A new fiber orientation tensor recovery function is embedded in the reconstruction algorithm to match reconstructions with the target characteristics of fiber orientation distribution. Second, a metamodeling module is established to improve the computational efficiency by creating the surrogates of mesoscale analyses. Third, the macroscale behaviors are predicted by an efficient multiscale model, in which the spatially varying material properties are obtained based on the local fiber orientation tensors. Our approach is further validated through experiments at both meso- and macro-scales, such as tensile tests assisted by Digital Image Correlation (DIC) and mesostructure imaging.« less

Multiscale finite element modeling of sheet molding compound (SMC) composite structure based on stochastic mesostructure reconstruction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Zhangxing; Huang, Tianyu; Shao, Yimin

Predicting the mechanical behavior of the chopped carbon fiber Sheet Molding Compound (SMC) due to spatial variations in local material properties is critical for the structural performance analysis but is computationally challenging. Such spatial variations are induced by the material flow in the compression molding process. In this work, a new multiscale SMC modeling framework and the associated computational techniques are developed to provide accurate and efficient predictions of SMC mechanical performance. The proposed multiscale modeling framework contains three modules. First, a stochastic algorithm for 3D chip-packing reconstruction is developed to efficiently generate the SMC mesoscale Representative Volume Element (RVE)more » model for Finite Element Analysis (FEA). A new fiber orientation tensor recovery function is embedded in the reconstruction algorithm to match reconstructions with the target characteristics of fiber orientation distribution. Second, a metamodeling module is established to improve the computational efficiency by creating the surrogates of mesoscale analyses. Third, the macroscale behaviors are predicted by an efficient multiscale model, in which the spatially varying material properties are obtained based on the local fiber orientation tensors. Our approach is further validated through experiments at both meso- and macro-scales, such as tensile tests assisted by Digital Image Correlation (DIC) and mesostructure imaging.« less

Polymeric compositions and their method of manufacture. [forming filled polymer systems using cryogenics

NASA Technical Reports Server (NTRS)

Moser, B. G.; Landel, R. F. (Inventor)

1972-01-01

Filled polymer compositions are made by dissolving the polymer binder in a suitable sublimable solvent, mixing the filler material with the polymer and its solvent, freezing the resultant mixture, and subliming the frozen solvent from the mixture from which it is then removed. The remaining composition is suitable for conventional processing such as compression molding or extruding. A particular feature of the method of manufacture is pouring the mixed solution slowly in a continuous stream into a cryogenic bath wherein frozen particles of the mixture result. The frozen individual particles are then subjected to the sublimation.

3D printing of polypropylene using the fused filament fabrication technique

NASA Astrophysics Data System (ADS)

Silva, A. F.; Carneiro, O. S.; Gomes, R.

2017-10-01

This work addresses the potential of polypropylene, neat (PP) and reinforced with short glass fibers (GRPP), as a candidate for the Fused Filament Fabrication (FFF)-based 3D printing technique. The entire production chain was evaluated, i.e., starting with PP and GRPP pellets, filaments were produced by extrusion and test samples were printed in different process conditions (different layers' thicknesses, deposition orientation and infill) with the in-house produced filaments. This strategy enabled a true comparison between parts printed (FFF) with parts manufactured by compression molding (CM), using exactly the same grade of raw material.

Analysis of the Effect of Surface Modification on Polyimide Composites Coated with Erosion Resistant Materials

NASA Technical Reports Server (NTRS)

Ndalama, Tchinga; Hirschfeld, Deidre; Sutter, James K. (Technical Monitor)

2003-01-01

The aim of this research is to enhance performance of composite coatings through modification of graphite-reinforced polyimide composite surfaces prior to metal bond coat/ hard topcoat application for use in the erosive and/or oxidative environments of advanced engines. Graphite reinforced polyimide composites, PMR-15 and PMR-II-50, formed by sheet molding and pre-pregging will be surface treated, overlaid with a bond coat and then coated with WC-Co. The surface treatment will include cleaning, RF plasma or ultraviolet light- ozone etching, and deposition of SiO(x) groups. These surface treatments will be studied in order to investigate and improve adhesion and oxidation resistance. The following panels were provided by NASA-Glenn Research Center(NASA-GRC): Eight compression molded PMR-II-50; 6 x 6 x 0.125 in. Two vacuum-bagged PMR-II-50; 12 x 12 x 0.125 in. Eight compression molded PMR-15; 6 x 6 x 0.125 in. One vacuum-bagged PMR-15; 12 x 12 x 0.125 in. All panels were made using a 12 x 12 in. T650-35 8HS (3K-tow) graphite fabric. A diamond-wafering blade, with deionized water as a cutting fluid, was used to cut PMR-II-50 and PMR-15 panels into 1 x 1 in. pieces for surface tests. The panel edges exhibiting delamination were used for the preliminary surface preparation tests as these would be unsuitable for strength and erosion testing. PMR-15 neat resin samples were also provided by NASA GRC. Surface profiles of the as-received samples were determined using a Dektak III Surface profile measuring system. Two samples of compression molded PMR-II-50 and PMR-15, vacuum-bagged PMR-II-50 and PMR-15 were randomly chosen for surface profile measurement according to ANSI/ASME B46.1. Prior to each measurement, the samples were blasted with compressed air to remove any artifacts. Five 10 mm-long scans were made on each sample. The short and long wavelength cutoff filter values were set at 100 and 1000 m, diamond stylus radius was 12.5 microns. Table 1 is a summary of the arithmetic average roughness (Ra) and waviness (Wa) for the composite surfaces.

Development of Ground Coils with Low Eddy Current Loss by Applying the Compression Molding Method after the Coil Winding

NASA Astrophysics Data System (ADS)

Suzuki, Masao; Aiba, Masayuki; Takahashi, Noriyuki; Ota, Satoru; Okada, Shigenori

In a magnetically levitated transportation (MAGLEV) system, a huge number of ground coils will be required because they must be laid for the whole line. Therefore, stable performance and reduced cost are essential requirements for the ground coil development. On the other hand, because the magnetic field changes when the superconducting magnet passes by, an eddy current will be generated in the conductor of the ground coil and will result in energy loss. The loss not only increases the magnetic resistance for the train running but also brings an increase in the ground coil temperature. Therefore, the reduction of the eddy current loss is extremely important. This study examined ground coils in which both the eddy current loss and temperature increase were small. Furthermore, quantitative comparison for the eddy current loss of various magnet wire samples was performed by bench test. On the basis of the comparison, a round twisted wire having low eddy current loss was selected as an effective ground coil material. In addition, the ground coils were manufactured on trial. A favorable outlook to improve the size accuracy of the winding coil and uneven thickness of molded resin was obtained without reducing the insulation strength between the coil layers by applying a compression molding after winding.

Silicon nitride sintered body

NASA Technical Reports Server (NTRS)

Suzuki, K.; Shinohara, N.

1984-01-01

The sintering of silicon carbide and it production are described. The method of production is by calcination in which molding is followed by sintering without compression. The invention improves the composition of the silicon carbide ceramic. Six examples of the invention are illustrated and discussed.

The beetle elytron plate: a lightweight, high-strength and buffering functional-structural bionic material.

PubMed

Zhang, Xiaoming; Xie, Juan; Chen, Jinxiang; Okabe, Yoji; Pan, Longcheng; Xu, Mengye

2017-06-30

To investigate the characteristics of compression, buffering and energy dissipation in beetle elytron plates (BEPs), compression experiments were performed on BEPs and honeycomb plates (HPs) with the same wall thickness in different core structures and using different molding methods. The results are as follows: 1) The compressive strength and energy dissipation capacity in the BEP are 2.44 and 5.0 times those in the HP, respectively, when the plates are prepared using the full integrated method (FIM). 2) The buckling stress is directly proportional to the square of the wall thickness (t). Thus, for core structures with equal wall thicknesses, although the core volume of the BEP is 42 percent greater than that of the HP, the mechanical properties of the BEP are several times higher than those of the HP. 3) It is also proven that even when the single integrated method (SIM) is used to prepare BEPs, the properties discussed above remain superior to those of HPs by a factor of several; this finding lays the foundation for accelerating the commercialization of BEPs based on modern manufacturing processes.

The reflectivity, wettability and scratch durability of microsurface features molded in the injection molding process using a dynamic tool tempering system

NASA Astrophysics Data System (ADS)

Kuhn, Sascha; Burr, August; Kübler, Michael; Deckert, Matthias; Bleesen, Christoph

2011-02-01

In this paper the replication qualities of periodically and randomly arranged micro-features molded in the injection molding process and their effects on surface properties are studied. The features are molded in PC, PMMA and PP at different mold wall temperatures in order to point out the necessity and profitability of a variotherm mold wall temperature control system. A one-dimensional heat conduction model is proposed to predict the cycle times of the variotherm injection molding processes. With regard to these processes, the molding results are compared to the molded surface feature heights using an atomic force microscope. In addition, the effects of the molded surface features on macroscopic surfaces are characterized in terms of light reflection using a spectrometer and in terms of water wettability by measuring the static contact angle. Furthermore, due to the sensitivity of the surface features on the molded parts, their durability is compared in a scratch test with a diamond tip. This leads to successful implementation in applications in which the optical appearance, in terms of gloss and reflection, and the water repellence, in terms of drag flow and adhesion, are of importance.

Modeling and flow analysis of pure nylon polymer for injection molding process

NASA Astrophysics Data System (ADS)

Nuruzzaman, D. M.; Kusaseh, N.; Basri, S.; Oumer, A. N.; Hamedon, Z.

2016-02-01

In the production of complex plastic parts, injection molding is one of the most popular industrial processes. This paper addresses the modeling and analysis of the flow process of the nylon (polyamide) polymer for injection molding process. To determine the best molding conditions, a series of simulations are carried out using Autodesk Moldflow Insight software and the processing parameters are adjusted. This mold filling commercial software simulates the cavity filling pattern along with temperature and pressure distributions in the mold cavity. In the modeling, during the plastics flow inside the mold cavity, different flow parameters such as fill time, pressure, temperature, shear rate and warp at different locations in the cavity are analyzed. Overall, this Moldflow is able to perform a relatively sophisticated analysis of the flow process of pure nylon. Thus the prediction of the filling of a mold cavity is very important and it becomes useful before a nylon plastic part to be manufactured.

Macroscopic strain controlled ion current in an elastomeric microchannel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuo, Chin-Chang; Nguyen, Du; Buchsbaum, Steven

We report on the fabrication of an ultra-high aspect ratio ionically conductive single microchannel with tunable diameter from ≈ 20 μm to fully closed. The 4 mm-long channel is fabricated in a Polydimethylsiloxane (PDMS) mold and its cross-sectional area is controlled by applying macroscopic compressive strain to the mold in a direction perpendicular to the channel length. We investigated the ionic conduction properties of the channel. For a wide range of compressive strain up to ≈ 0.27, the strain dependence of the resistance is monotonic and fully reversible. For strain > 0.27, ionic conduction suddenly shuts off and the system becomes hystereticmore » (whereby a finite strain reduction is required to reopen the channel). Upon unloading, the original behavior is retrieved. This reversible behavior is observed over 200 compression cycles. The cross-sectional area of the channel can be inferred from the ion current measurement, as confirmed by a Nano-Computed Tomography investigation. We show that the cross-sectional area decreases monotonically with the applied compressive strain in the reversible range, in qualitative agreement with linear elasticity theory. We find that the shut-off strain is affected by the spatial extent of the applied strain, which provides additional tunability. Our tunable channel is well-suited for multiple applications in micro/nano-fluidic devices.« less

Morphological changes of the caudal cervical intervertebral foramina due to flexion-extension and compression-traction movements in the canine cervical vertebral column.

PubMed

Ramos, Renato M; da Costa, Ronaldo C; Oliveira, Andre L A; Kodigudla, Manoj K; Goel, Vijay K

2015-08-06

Previous studies in humans have reported that the dimensions of the intervertebral foramina change significantly with movement of the spine. Cervical spondylomyelopathy (CSM) in dogs is characterized by dynamic and static compressions of the neural components, leading to variable degrees of neurologic deficits and neck pain. Studies suggest that intervertebral foraminal stenosis has implications in the pathogenesis of CSM. The dimensions of the cervical intervertebral foramina may significantly change during neck movements. This could have implication in the pathogenesis of CSM and other diseases associated with radiculopathy such as intervertebral disc disease. The purpose of this study was to quantify the morphological changes in the intervertebral foramina of dogs during flexion, extension, traction, and compression of the canine cervical vertebral column. All vertebral columns were examined with magnetic resonance imaging prior to biomechanic testing. Eight normal vertebral columns were placed in Group 1 and eight vertebral columns with intervertebral disc degeneration or/and protrusion were assigned to Group 2. Molds of the left and right intervertebral foramina from C4-5, C5-6 and C6-7 were taken during all positions and loading modes. Molds were frozen and vertical (height) and horizontal (width) dimensions of the foramina were measured. Comparisons were made between neutral to flexion and extension, flexion to extension, and traction to compression in neutral position. Extension decreased all the foraminal dimensions significantly, whereas flexion increased all the foraminal dimensions significantly. Compression decreased all the foraminal dimensions significantly, and traction increased the foraminal height, but did not significantly change the foraminal width. No differences in measurements were seen between groups. Our results show movement-related changes in the dimensions of the intervertebral foramina, with significant foraminal narrowing in extension and compression.

Fabrication Of Carbon-Boron Reinforced Dry Polymer Matrix Composite Tape

NASA Technical Reports Server (NTRS)

Belvin, Harry L.; Cano, Roberto J.; Treasure, Monte; Shahood, Thomas W.

1999-01-01

Future generation aerospace vehicles will require specialized hybrid material forms for component structure fabrication. For this reason, high temperature composite prepregs in both dry and wet forms are being developed at NASA Langley Research Center (LaRC). In an attempt to improve compressive properties of carbon fiber reinforced composites, a hybrid carbon-boron tape was developed and used to fabricate composite laminates which were subsequently cut into flexural and compression specimens and tested. The hybrid material, given the designation HYCARB, was fabricated by modifying a previously developed process for the manufacture of dry polymer matrix composite (PMC) tape at LaRC. In this work, boron fibers were processed with IM7/LaRC(TradeMark)IAX poly(amide acid) solution-coated prepreg to form a dry hybrid tape for Automated Tow Placement (ATP). Boron fibers were encapsulated between two (2) layers of reduced volatile, low fiber areal weight poly(amide acid) solution-coated prepreg. The hybrid prepreg was then fully imidized and consolidated into a dry tape suitable for ATP. The fabrication of a hybrid boron material form for tow placement aids in the reduction of the overall manufacturing cost of boron reinforced composites, while realizing the improved compression strengths. Composite specimens were press-molded from the hybrid material and exhibited excellent mechanical properties.

Mechanical and toxicological evaluation of concrete artifacts containing waste foundry sand.

PubMed

Mastella, Miguel Angelo; Gislon, Edivelton Soratto; Pelisser, Fernando; Ricken, Cláudio; da Silva, Luciano; Angioletto, Elídio; Montedo, Oscar Rubem Klegues

2014-08-01

The creation of metal parts via casting uses molds that are generally made from sand and phenolic resin. The waste generated after the casting process is called waste foundry sand (WFS). Depending on the mold composition and the casting process, WFS can contain substances that prevent its direct emission to the environment. In Brazil, this waste is classified according to the Standard ABNT NBR 10004:2004 as a waste Class II (Non-Inert). The recycling of this waste is limited because its characteristics change significantly after use. Although the use (or reuse) of this byproduct in civil construction is a technically feasible alternative, its effects must be evaluated, especially from mechanical and environmental points of view. Thus, the objective of this study is to investigate the effect of the use of WFS in the manufacture of cement artifacts, such as masonry blocks for walls, structural masonry blocks, and paving blocks. Blocks containing different concentrations of WFS (up to 75% by weight) were produced and evaluated using compressive strength tests (35 MPa at 28 days) and toxicity tests on Daphnia magna, Allium cepa (onion root), and Eisenia foetida (earthworm). The results showed that there was not a considerable reduction in the compressive strength, with values of 35 ± 2 MPa at 28 days. The toxicity study with the material obtained from leaching did not significantly interfere with the development of D. magna and E. foetida, but the growth of the A. cepa species was reduced. The study showed that the use of this waste in the production of concrete blocks is feasible from both mechanical and environmental points of view. Copyright © 2014 Elsevier Ltd. All rights reserved.

A new method of fabricating a blend scaffold using an indirect three-dimensional printing technique.

PubMed

Jung, Jin Woo; Lee, Hyungseok; Hong, Jung Min; Park, Jeong Hun; Shim, Jung Hee; Choi, Tae Hyun; Cho, Dong-Woo

2015-11-03

Due to its simplicity and effectiveness, the physical blending of polymers is considered to be a practical strategy for developing a versatile scaffold having desirable mechanical and biochemical properties. In the present work, an indirect three-dimensional (i3D) printing technique was proposed to fabricate a 3D free-form scaffold using a blend of immiscible materials, such as polycaprolactone (PCL) and gelatin. The i3D printing technique includes 3D printing of a mold and a sacrificial molding process. PCL/chloroform and gelatin/water were physically mixed to prepare the blend solution, which was subsequently injected into the cavity of a 3D printed mold. After solvent removal and gelatin cross-linking, the mold was dissolved to obtain a PCL-gelatin (PG) scaffold, with a specific 3D structure. Scanning electron microscopy and Fourier transform infrared spectroscopy analysis indicated that PCL masses and gelatin fibers in the PG scaffold homogenously coexisted without chemical bonding. Compression tests confirmed that gelatin incorporation into the PCL enhanced its mechanical flexibility and softness, to the point of being suitable for soft-tissue engineering, as opposed to pure PCL. Human adipose-derived stem cells, cultured on a PG scaffold, exhibited enhanced in vitro chondrogenic differentiation and tissue formation, compared with those on a PCL scaffold. The i3D printing technique can be used to blend a variety of materials, facilitating 3D scaffold fabrication for specific tissue regeneration. Furthermore, this convenient and versatile technique may lead to wider application of 3D printing in tissue engineering.

[Correlation between physical characteristics of sticks and quality of traditional Chinese medicine pills prepared by plastic molded method].

PubMed

Wang, Ling; Xian, Jiechen; Hong, Yanlong; Lin, Xiao; Feng, Yi

2012-05-01

To quantify the physical characteristics of sticks of traditional Chinese medicine (TCM) honeyed pills prepared by the plastic molded method and the correlation of adhesiveness and plasticity-related parameters of sticks and quality of pills, in order to find major parameters and the appropriate range impacting pill quality. Sticks were detected by texture analyzer for their physical characteristic parameters such as hardness and compression action, and pills were observed by visual evaluation for their quality. The correlation of both data was determined by the stepwise discriminant analysis. Stick physical characteristic parameter l(CD) can exactly depict the adhesiveness, with the discriminant equation of Y0 - Y1 = 6.415 - 41.594l(CD). When Y0 < Y1, pills were scattered well; when Y0 > Y1, pills were adhesive with each other. Pills' physical characteristic parameters l(CD) and l(AC), Ar, Tr can exactly depict smoothness of pills, with the discriminant equation of Z0 - Z1 = -195.318 + 78.79l(AC) - 3 258. 982Ar + 3437.935Tr. When Z0 < Z1, pills were smooth on surface. When Z0 > Z1, pills were rough on surface. The stepwise discriminant analysis is made to show the obvious correlation between key physical characteristic parameters l(CD) and l(AC), Ar, Tr of sticks and appearance quality of pills, defining the molding process for preparing pills by the plastic molded and qualifying ranges of key physical characteristic parameters characterizing intermediate sticks, in order to provide theoretical basis for prescription screening and technical parameter adjustment for pills.

Testing single point incremental forming molds for thermoforming operations

NASA Astrophysics Data System (ADS)

Afonso, Daniel; de Sousa, Ricardo Alves; Torcato, Ricardo

2016-10-01

Low pressure polymer processing processes as thermoforming or rotational molding use much simpler molds then high pressure processes like injection. However, despite the low forces involved with the process, molds manufacturing for this operations is still a very material, energy and time consuming operation. The goal of the research is to develop and validate a method for manufacturing plastically formed sheets metal molds by single point incremental forming (SPIF) operation for thermoforming operation. Stewart platform based SPIF machines allow the forming of thick metal sheets, granting the required structural stiffness for the mold surface, and keeping the short lead time manufacture and low thermal inertia.

A comparative study between melt granulation/compression and hot melt extrusion/injection molding for the manufacturing of oral sustained release thermoplastic polyurethane matrices.

PubMed

Verstraete, G; Mertens, P; Grymonpré, W; Van Bockstal, P J; De Beer, T; Boone, M N; Van Hoorebeke, L; Remon, J P; Vervaet, C

2016-11-20

During this project 3 techniques (twin screw melt granulation/compression (TSMG), hot melt extrusion (HME) and injection molding (IM)) were evaluated for the manufacturing of thermoplastic polyurethane (TPU)-based oral sustained release matrices, containing a high dose of the highly soluble metformin hydrochloride. Whereas formulations with a drug load between 0 and 70% (w/w) could be processed via HME/(IM), the drug content of granules prepared via melt granulation could only be varied between 85 and 90% (w/w) as these formulations contained the proper concentration of binder (i.e. TPU) to obtain a good size distribution of the granules. While release from HME matrices and IM tablets could be sustained over 24h, release from the TPU-based TSMG tablets was too fast (complete release within about 6h) linked to their higher drug load and porosity. By mixing hydrophilic and hydrophobic TPUs the in vitro release kinetics of both formulations could be adjusted: a higher content of hydrophobic TPU was correlated with a slower release rate. Although mini-matrices showed faster release kinetics than IM tablets, this observation was successfully countered by changing the hydrophobic/hydrophilic TPU ratio. In vivo experiments via oral administration to dogs confirmed the versatile potential of the TPU platform as intermediate-strong and low-intermediate sustained characteristics were obtained for the IM tablets and HME mini-matrices, respectively. Copyright © 2016 Elsevier B.V. All rights reserved.

Effects of process parameters in plastic, metal, and ceramic injection molding processes

NASA Astrophysics Data System (ADS)

Lee, Shi W.; Ahn, Seokyoung; Whang, Chul Jin; Park, Seong Jin; Atre, Sundar V.; Kim, Jookwon; German, Randall M.

2011-09-01

Plastic injection molding has been widely used in the past and is a dominant forming approach today. As the customer demands require materials with better engineering properties that were not feasible with polymers, powder injection molding with metal and ceramic powders has received considerable attention in recent decades. To better understand the differences in the plastic injection molding, metal injection molding, and ceramic injection molding, the effects of the core process parameters on the process performances has been studied using the state-of-the-art computer-aided engineering (CAE) design tool, PIMSolver® The design of experiments has been conducted using the Taguchi method to obtain the relative contributions of various process parameters onto the successful operations.

Precision molding of advanced glass optics: innovative production technology for lens arrays and free form optics

NASA Astrophysics Data System (ADS)

Pongs, Guido; Bresseler, Bernd; Bergs, Thomas; Menke, Gert

2012-10-01

Today isothermal precision molding of imaging glass optics has become a widely applied and integrated production technology in the optical industry. Especially in consumer electronics (e.g. digital cameras, mobile phones, Blu-ray) a lot of optical systems contain rotationally symmetrical aspherical lenses produced by precision glass molding. But due to higher demands on complexity and miniaturization of optical elements the established process chain for precision glass molding is not sufficient enough. Wafer based molding processes for glass optics manufacturing become more and more interesting for mobile phone applications. Also cylindrical lens arrays can be used in high power laser systems. The usage of unsymmetrical free-form optics allows an increase of efficiency in optical laser systems. Aixtooling is working on different aspects in the fields of mold manufacturing technologies and molding processes for extremely high complex optical components. In terms of array molding technologies, Aixtooling has developed a manufacturing technology for the ultra-precision machining of carbide molds together with European partners. The development covers the machining of multi lens arrays as well as cylindrical lens arrays. The biggest challenge is the molding of complex free-form optics having no symmetrical axis. A comprehensive CAD/CAM data management along the entire process chain is essential to reach high accuracies on the molded lenses. Within a national funded project Aixtooling is working on a consistent data handling procedure in the process chain for precision molding of free-form optics.

Remelt Ingot Production Technology

NASA Astrophysics Data System (ADS)

Grandfield, J. F.

The technology related to the production of remelt ingots (small ingots, sows and T-Bar) is reviewed. Open mold conveyors, sow casting, wheel and belt casting and VDC and HDC casting are described and compared. Process economics, capacity, product quality and process problems are listed. Trends in casting machine technology such as longer open mold conveyor lines are highlighted. Safety issues related to the operation of these processes are discussed. The advantages and disadvantages of the various machine configurations and options e.g. such as dry filling with the mold out of water and wet filling with the mold in water for open mould conveyors are discussed. The effect of mold design on machine productivity, mold cracking and mold life is also examined.

[Contribution of the physical and rehabilitation medicine in pediatric plastic surgery].

PubMed

Gottrand, L; Devinck, F; Martinot Duquennoy, V; Guerreschi, P

2016-10-01

Physical, non-painful processes guide the scar reshaping in children in order to prevent growth anomalies due to cutaneous shrinkage. The objective of the surgical treatment, coordinated with the reeducation care, is to improve the physical abilities of the skin, to restore the function and avoid the deformations. Reeducation uses various techniques (i.e. sensitive-motility, massage and mobilizations) with or without physical agent (water, aspiration and touch-drive technique). Posture and positioning rely on the small or major aids, from orthosis to prosthesis. Compression is obtained by the adjustment of aids on molding and compression garment. Indications of the reeducation treatment depend on the timing of cutaneous covering and the advance of the healing process. It also depends on the underlying condition including skin traumas (frictions, wounds, burns), skin surgeries (purpura fulminans consequences, skin graft reconstruction after giant nevus resection, malignant lesion or vascular malformations). The final goal is the rehabilitation and development of the child and the adolescent in its entire somatopsychic dimension. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

A hybrid optimization approach in non-isothermal glass molding

NASA Astrophysics Data System (ADS)

Vu, Anh-Tuan; Kreilkamp, Holger; Krishnamoorthi, Bharathwaj Janaki; Dambon, Olaf; Klocke, Fritz

2016-10-01

Intensively growing demands on complex yet low-cost precision glass optics from the today's photonic market motivate the development of an efficient and economically viable manufacturing technology for complex shaped optics. Against the state-of-the-art replication-based methods, Non-isothermal Glass Molding turns out to be a promising innovative technology for cost-efficient manufacturing because of increased mold lifetime, less energy consumption and high throughput from a fast process chain. However, the selection of parameters for the molding process usually requires a huge effort to satisfy precious requirements of the molded optics and to avoid negative effects on the expensive tool molds. Therefore, to reduce experimental work at the beginning, a coupling CFD/FEM numerical modeling was developed to study the molding process. This research focuses on the development of a hybrid optimization approach in Non-isothermal glass molding. To this end, an optimal configuration with two optimization stages for multiple quality characteristics of the glass optics is addressed. The hybrid Back-Propagation Neural Network (BPNN)-Genetic Algorithm (GA) is first carried out to realize the optimal process parameters and the stability of the process. The second stage continues with the optimization of glass preform using those optimal parameters to guarantee the accuracy of the molded optics. Experiments are performed to evaluate the effectiveness and feasibility of the model for the process development in Non-isothermal glass molding.

33. BENCH CORE STATION, GREY IRON FOUNDRY CORE ROOM WHERE ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

33. BENCH CORE STATION, GREY IRON FOUNDRY CORE ROOM WHERE CORE MOLDS WERE HAND FILLED AND OFTEN PNEUMATICALLY COMPRESSED WITH A HAND-HELD RAMMER BEFORE THEY WERE BAKED. - Stockham Pipe & Fittings Company, Grey Iron Foundry, 4000 Tenth Avenue North, Birmingham, Jefferson County, AL

Effect of molding conditions on fracture mechanisms and stiffness of a composite of grid structure

NASA Astrophysics Data System (ADS)

Nikolaev, V. P.; Pichugin, V. S.; Korobeinikov, A. G.

1999-01-01

Methods of determining a complex of stiffness and deformability characteristics of a composite with rhomb-type grid structure were elaborated. Rhomb-type specimens were used for testing the ribs of the structure in tension, compression, and bending and the nodal points in shear in the plane of the ribs. The effect of additional tensioning of the ribs preceding the curing of the binder was investigated (ten tensioning levels ranging from 8 to 70 N/bundle with a linear density of 390 tex were applied). In testing epoxy-carbon specimens (UKN-5000+EHD-MK) in compression and tension, the failure mode changed depending on the tensioning level, i.e., the presence or absence of delamination and the appearance of "dry" fibers were detected. Dependences of the mechanical properties on tensioning were of a markedly pronounced extreme nature. The methods elaborated allow us to investigate the effect of other molding parameters, as well as the conditions and nature of loading, on the mechanical characteristics of composites.

Biopolymer foams - Relationship between material characteristics and foaming behavior of cellulose based foams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rapp, F., E-mail: florian.rapp@ict.fraunhofer.de, E-mail: anja.schneider@ict.fraunhofer.de; Schneider, A., E-mail: florian.rapp@ict.fraunhofer.de, E-mail: anja.schneider@ict.fraunhofer.de; Elsner, P., E-mail: peter.elsner@ict.fraunhofer.de

2014-05-15

Biopolymers are becoming increasingly important to both industry and consumers. With regard to waste management, CO{sub 2} balance and the conservation of petrochemical resources, increasing efforts are being made to replace standard plastics with bio-based polymers. Nowadays biopolymers can be built for example of cellulose, lactic acid, starch, lignin or bio mass. The paper will present material properties of selected cellulose based polymers (cellulose propionate [CP], cellulose acetate butyrate [CAB]) and corresponding processing conditions for particle foams as well as characterization of produced parts. Special focus is given to the raw material properties by analyzing thermal behavior (differential scanning calorimetry),more » melt strength (Rheotens test) and molecular weight distribution (gel-permeation chromatography). These results will be correlated with the foaming behavior in a continuous extrusion process with physical blowing agents and underwater pelletizer. Process set-up regarding particle foam technology, including extrusion foaming and pre-foaming, will be shown. The characteristics of the resulting foam beads will be analyzed regarding part density, cell morphology and geometry. The molded parts will be tested on thermal conductivity as well as compression behavior (E-modulus, compression strength)« less

Spinoff From a Moon Suit

NASA Technical Reports Server (NTRS)

1991-01-01

Al Gross transferred expertise obtained as an ILC engineer for NASA's Apollo program to the manufacture of athletic shoes. Gross substituted DuPont's Hytrel plastic for foam materials in the shoe's midsole, eliminating cushioning loss caused by body weight. An external pressurized shell applied from space suit technology was incorporated into the shoe. Stiffness and cushioning properties of the midsole were "tuned" by varying material thickness and styling lines. A stress free "blow molding" process adapted from NASA space suit design was also utilized. The resulting compression chamber midsole performed well in tests. It allows AVIA to re-configure for specific sports and is a "first step" toward a durable, foamless, non-fatiguing midsole.

Processing and Characterization of Cellulose Nanocrystals/Polylactic Acid Nanocomposite Films

PubMed Central

Sullivan, Erin M.; Moon, Robert J.; Kalaitzidou, Kyriaki

2015-01-01

The focus of this study is to examine the effect of cellulose nanocrystals (CNC) on the properties of polylactic acid (PLA) films. The films are fabricated via melt compounding and melt fiber spinning followed by compression molding. Film fracture morphology, thermal properties, crystallization behavior, thermo-mechanical behavior, and mechanical behavior were determined as a function of CNC content using scanning electron microscopy, differential scanning calorimetry, X-ray diffraction, dynamic mechanical analysis, and tensile testing. Film crystallinity increases with increasing CNC content indicating CNC act as nucleating agents, promoting crystallization. Furthermore, the addition of CNC increased the film storage modulus and slightly broadened the glass transition region. PMID:28793701

Development of integrated control system for smart factory in the injection molding process

NASA Astrophysics Data System (ADS)

Chung, M. J.; Kim, C. Y.

2018-03-01

In this study, we proposed integrated control system for automation of injection molding process required for construction of smart factory. The injection molding process consists of heating, tool close, injection, cooling, tool open, and take-out. Take-out robot controller, image processing module, and process data acquisition interface module are developed and assembled to integrated control system. By adoption of integrated control system, the injection molding process can be simplified and the cost for construction of smart factory can be inexpensive.

Thermal stability of poly(3-hydroxybutyrate)/vegetable fiber composites

NASA Astrophysics Data System (ADS)

Cipriano, Pâmela Bento; de Sá, Mayelli Dantas; Andrade, André L. Simões; de Carvalho, Laura Hecker; Canedo, Eduardo Luis

2015-05-01

The present work deals with the thermal stability during and after processing of composites of poly(3-hydroxybutyrate) (PHB) - a fully biodegradable semi-crystalline thermoplastic obtained from renewable resources through low-impact biotechnological process, biocompatible and non-toxic - and vegetable fiber from the fruit (coconut) of babassu palm tree. PHB/babassu composites with 0, 5, 10 and 20% w/w load were prepared in a laboratory internal mixer. Two fractions of the mesocarp of babassu with different particle sizes were compounded with PHB and test specimens molded by compression. The effect of loading level and processing conditions on torque, temperature and mechanical energy dissipation were studied using a new engineering model. It was found that PHB degrades during processing at temperatures slightly above the melting point. To minimize thermal degradation stabilizer and chain extender additives were incorporated, with mixed results. These findings were confirmed by the dependence of the melt flow rate on the processing temperature.

A programmable nanoreplica molding for the fabrication of nanophotonic devices.

PubMed

Liu, Longju; Zhang, Jingxiang; Badshah, Mohsin Ali; Dong, Liang; Li, Jingjing; Kim, Seok-min; Lu, Meng

2016-03-01

The ability to fabricate periodic structures with sub-wavelength features has a great potential for impact on integrated optics, optical sensors, and photovoltaic devices. Here, we report a programmable nanoreplica molding process to fabricate a variety of sub-micrometer periodic patterns using a single mold. The process utilizes a stretchable mold to produce the desired periodic structure in a photopolymer on glass or plastic substrates. During the replica molding process, a uniaxial force is applied to the mold and results in changes of the periodic structure, which resides on the surface of the mold. Direction and magnitude of the force determine the array geometry, including the lattice constant and arrangement. By stretching the mold, 2D arrays with square, rectangular, and triangular lattice structures can be fabricated. As one example, we present a plasmonic crystal device with surface plasmon resonances determined by the force applied during molding. In addition, photonic crystal slabs with different array patterns are fabricated and characterized. This unique process offers the capability of generating various periodic nanostructures rapidly and inexpensively.

Rapid and low-cost prototyping of medical devices using 3D printed molds for liquid injection molding.

PubMed

Chung, Philip; Heller, J Alex; Etemadi, Mozziyar; Ottoson, Paige E; Liu, Jonathan A; Rand, Larry; Roy, Shuvo

2014-06-27

Biologically inert elastomers such as silicone are favorable materials for medical device fabrication, but forming and curing these elastomers using traditional liquid injection molding processes can be an expensive process due to tooling and equipment costs. As a result, it has traditionally been impractical to use liquid injection molding for low-cost, rapid prototyping applications. We have devised a method for rapid and low-cost production of liquid elastomer injection molded devices that utilizes fused deposition modeling 3D printers for mold design and a modified desiccator as an injection system. Low costs and rapid turnaround time in this technique lower the barrier to iteratively designing and prototyping complex elastomer devices. Furthermore, CAD models developed in this process can be later adapted for metal mold tooling design, enabling an easy transition to a traditional injection molding process. We have used this technique to manufacture intravaginal probes involving complex geometries, as well as overmolding over metal parts, using tools commonly available within an academic research laboratory. However, this technique can be easily adapted to create liquid injection molded devices for many other applications.

A programmable nanoreplica molding for the fabrication of nanophotonic devices

PubMed Central

Liu, Longju; Zhang, Jingxiang; Badshah, Mohsin Ali; Dong, Liang; Li, Jingjing; Kim, Seok-min; Lu, Meng

2016-01-01

The ability to fabricate periodic structures with sub-wavelength features has a great potential for impact on integrated optics, optical sensors, and photovoltaic devices. Here, we report a programmable nanoreplica molding process to fabricate a variety of sub-micrometer periodic patterns using a single mold. The process utilizes a stretchable mold to produce the desired periodic structure in a photopolymer on glass or plastic substrates. During the replica molding process, a uniaxial force is applied to the mold and results in changes of the periodic structure, which resides on the surface of the mold. Direction and magnitude of the force determine the array geometry, including the lattice constant and arrangement. By stretching the mold, 2D arrays with square, rectangular, and triangular lattice structures can be fabricated. As one example, we present a plasmonic crystal device with surface plasmon resonances determined by the force applied during molding. In addition, photonic crystal slabs with different array patterns are fabricated and characterized. This unique process offers the capability of generating various periodic nanostructures rapidly and inexpensively. PMID:26925828

Interface conditions of two-shot molded parts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kisslinger, Thomas, E-mail: thomas.kisslinger@pccl.at; Bruckmoser, Katharina, E-mail: katharina.bruckmoser@unileoben.ac.at; Resch, Katharina, E-mail: katharina.resch@unileoben.ac.at

2014-05-15

The focus of this work is on interfaces of two-shot molded parts. It is well known that e.g. material combination, process parameters and contact area structures show significant effects on the bond strength of multi-component injection molded parts. To get information about the bond strength at various process parameter settings and material combinations a test mold with core back technology was used to produce two-component injection molded tensile test specimens. At the core back process the different materials are injected consecutively, so each component runs through the whole injection molding cycle (two-shot process). Due to this consecutive injection molding processes,more » a cold interface is generated. This is defined as overmolding of a second melt to a solidified polymer preform. Strong interest lies in the way the interface conditions change during the adhesion formation between the individual components. Hence the interface conditions were investigated by computed tomography and Raman spectroscopy. By analyzing these conditions the understanding of the adhesion development during the multi-component injection molding was improved.« less

Rotational molding of pultruded profiles reinforced polyethylene

NASA Astrophysics Data System (ADS)

Greco, Antonio; Maffezzoli, Alfonso; Romano, Giorgio

2014-05-01

The aim of this paper is the production of fiber reinforced LLDPE components by rotational molding. To this purpose, a process upgrade was developed, for the incorporation of pultruded tapes in the rotational molding cycle. Pultruded tapes, made of 50% by weight of glass fibers dispersed in a high density polyethylene(HDPE) matrix, were glued on the internal surface of a cubic mold, and rotational molding process was run using the same processing conditions used for conventional LLDPE processing. During processing, melting of LLDPE powders and of HDPE allowed to incorporate the tapes inside rotational molded LLDPE. The glass fiber reinforced prototypes were characterized in terms of mechanical properties. Plate bending tests were performed on the square faces extracted from the rotational molded product. The rotational molding products were also subjected to internal hydrostatic pressure tests up to 10 bar. In any case, no failure of the cubic samples was observed. In both cases, it was found that addition of a single pultruded strips, which corresponds to addition of about 0.6% by weight of glass fibers, involved an increase of the stiffness of the faces by about 25%.

Mathematical modeling of the process of filling a mold during injection molding of ceramic products

NASA Astrophysics Data System (ADS)

Kulkov, S. N.; Korobenkov, M. V.; Bragin, N. A.

2015-10-01

Using the software package Fluent it have been predicted of the filling of a mold in injection molding of ceramic products is of great importance, because the strength of the final product is directly related to the presence of voids in the molding, making possible early prediction of inaccuracies in the mold prior to manufacturing. The calculations were performed in the formulation of mathematical modeling of hydrodynamic turbulent process of filling a predetermined volume of a viscous liquid. The model used to determine the filling forms evaluated the influence of density and viscosity of the feedstock, and the injection pressure on the mold filling process to predict the formation of voids in the area caused by the shape defect geometry.

Optimization of injection molding process parameters for a plastic cell phone housing component

NASA Astrophysics Data System (ADS)

Rajalingam, Sokkalingam; Vasant, Pandian; Khe, Cheng Seong; Merican, Zulkifli; Oo, Zeya

2016-11-01

To produce thin-walled plastic items, injection molding process is one of the most widely used application tools. However, to set optimal process parameters is difficult as it may cause to produce faulty items on injected mold like shrinkage. This study aims at to determine such an optimum injection molding process parameters which can reduce the fault of shrinkage on a plastic cell phone cover items. Currently used setting of machines process produced shrinkage and mis-specified length and with dimensions below the limit. Thus, for identification of optimum process parameters, maintaining closer targeted length and width setting magnitudes with minimal variations, more experiments are needed. The mold temperature, injection pressure and screw rotation speed are used as process parameters in this research. For optimal molding process parameters the Response Surface Methods (RSM) is applied. The major contributing factors influencing the responses were identified from analysis of variance (ANOVA) technique. Through verification runs it was found that the shrinkage defect can be minimized with the optimal setting found by RSM.

Study of injection molded microcellular polyamide-6 nanocomposites

Treesearch

Mingjun Yuan; Lih-Sheng Turng; Shaoqin Gong; Daniel Caulfield; Chris Hunt; Rick Spindler

2004-01-01

This study aims to explore the processing benefits and property improvements of combining nanocomposites with microcellular injection molding. The microcellular nanocomposite processing was performed on an injection-molding machine equipped with a commercially available supercritical fluid (SCF) system. The molded samples produced based on the Design of Experiments (...

Static Mixer for Heat Transfer Enhancement for Mold Cooling Application

NASA Astrophysics Data System (ADS)

Becerra, Rodolfo; Barbosa, Raul; Lee, Kye-Hwan; Park, Younggil

Injection molding is the process by which a material is melted in a barrel and then it is injected through a nozzle in the mold cavity. When it cools down, the material solidifies into the shape of the cavity. Typical injection mold has cooling channels to maintain constant mold temperature during injection molding process. Even and constant temperature throughout the mold are very critical for a part quality and productivity. Conformal cooling improves the quality and productivity of injection molding process through the implementation of cooling channels that ``conform'' to the shape of the molded part. Recent years, the use of conformal cooling increases with advance of 3D printing technology such as Selective Laser Melting (SLM). Although it maximizes cooling, material and dimension limitations make SLM methods highly expensive. An alternative is the addition of static mixers in the molds with integrated cooling channels. A static mixer is a motionless mixing device that enhances heat transfer by producing improved flow mixing in the pipeline. In this study, the performance of the cooling channels will be evaluated with and without static mixers, by measuring temperature, pressure drop, and flow rate. The following question is addressed: Can a static mixer effectively enhance heat transfer for mold cooling application processes? This will provide insight on the development of design methods and guidelines that can be used to increase cooling efficiency at a lower cost.

Flow Kills Conductivity of Single Wall Carbon Nanotubes (SWNT) Composites

NASA Astrophysics Data System (ADS)

Bhatt, Sanjiv; Macosko, Christopher

2006-03-01

Most composites of polymer and single wall carbon nanotubes (SWNT) reported in the literature are made by solvent casting or simple compression molding. Commercial utility of these composites requires use of precision injection molding. We have observed a unique behavior wherein the SWNT composites made by injection molding or by extrusion are insulators but upon heating become electrically conductive. This behavior appears to be the result of a relaxation phenomenon in the SWNT composite. During flow into an injection mold or through an extrusion die the well-dispersed SWNT in the polymer matrix tend to align such that they are not in contact with each other and are farther than the minimum required distance, 5 nm (1), to achieve electrical percolation through electron hopping. Upon heating the SWNT relax and either touch each other or are at a distance less than or equal to 5 nm from each other to create a percolating. [1] Du, F., Scogna, R, C., Zhou, W., Brand, Stijn, Fischer, J. E., and Winey, K. I., Macromolecules 2004, 37, 9048-9055.

A Review of Metal Injection Molding- Process, Optimization, Defects and Microwave Sintering on WC-Co Cemented Carbide

NASA Astrophysics Data System (ADS)

Shahbudin, S. N. A.; Othman, M. H.; Amin, Sri Yulis M.; Ibrahim, M. H. I.

2017-08-01

This article is about a review of optimization of metal injection molding and microwave sintering process on tungsten cemented carbide produce by metal injection molding process. In this study, the process parameters for the metal injection molding were optimized using Taguchi method. Taguchi methods have been used widely in engineering analysis to optimize the performance characteristics through the setting of design parameters. Microwave sintering is a process generally being used in powder metallurgy over the conventional method. It has typical characteristics such as accelerated heating rate, shortened processing cycle, high energy efficiency, fine and homogeneous microstructure, and enhanced mechanical performance, which is beneficial to prepare nanostructured cemented carbides in metal injection molding. Besides that, with an advanced and promising technology, metal injection molding has proven that can produce cemented carbides. Cemented tungsten carbide hard metal has been used widely in various applications due to its desirable combination of mechanical, physical, and chemical properties. Moreover, areas of study include common defects in metal injection molding and application of microwave sintering itself has been discussed in this paper.

Method of making a wooden wind turbine blade

DOEpatents

Coleman, Clint

1984-01-01

A wooden wind turbine blade is formed by laminating wood veneer in a compression mold having the exact curvature needed for one side of the blade, following which the other side of the blade is ground flat along its length but twisted with respect to the blade axis.

Method of making a wooden wind turbine blade

DOEpatents

Coleman, C.

1984-08-14

A wooden wind turbine blade is formed by laminating wood veneer in a compression mold having the exact curvature needed for one side of the blade, following which the other side of the blade is ground flat along its length but twisted with respect to the blade axis. 8 figs.

Polymer composites prepared from heat-treated starch and styrene-butadiene latex

USDA-ARS?s Scientific Manuscript database

Thermoplastic starch/latex polymer composites were prepared using styrene–butadiene (SB) latex and heat-treated cornstarch. The composites were prepared in a compression mold at 130 °C, with starch content 20%. An amylose-free cornstarch, waxy maize, was used for this research and the heat treatment...

Rapid and Low-cost Prototyping of Medical Devices Using 3D Printed Molds for Liquid Injection Molding

PubMed Central

Chung, Philip; Heller, J. Alex; Etemadi, Mozziyar; Ottoson, Paige E.; Liu, Jonathan A.; Rand, Larry; Roy, Shuvo

2014-01-01

Biologically inert elastomers such as silicone are favorable materials for medical device fabrication, but forming and curing these elastomers using traditional liquid injection molding processes can be an expensive process due to tooling and equipment costs. As a result, it has traditionally been impractical to use liquid injection molding for low-cost, rapid prototyping applications. We have devised a method for rapid and low-cost production of liquid elastomer injection molded devices that utilizes fused deposition modeling 3D printers for mold design and a modified desiccator as an injection system. Low costs and rapid turnaround time in this technique lower the barrier to iteratively designing and prototyping complex elastomer devices. Furthermore, CAD models developed in this process can be later adapted for metal mold tooling design, enabling an easy transition to a traditional injection molding process. We have used this technique to manufacture intravaginal probes involving complex geometries, as well as overmolding over metal parts, using tools commonly available within an academic research laboratory. However, this technique can be easily adapted to create liquid injection molded devices for many other applications. PMID:24998993

Intelligent process development of foam molding for the Thermal Protection System (TPS) of the space shuttle external tank

NASA Technical Reports Server (NTRS)

Bharwani, S. S.; Walls, J. T.; Jackson, M. E.

1987-01-01

A knowledge based system to assist process engineers in evaluating the processability and moldability of poly-isocyanurate (PIR) formulations for the thermal protection system of the Space Shuttle external tank (ET) is discussed. The Reaction Injection Molding- Process Development Advisor (RIM-PDA) is a coupled system which takes advantage of both symbolic and numeric processing techniques. This system will aid the process engineer in identifying a startup set of mold schedules and in refining the mold schedules to remedy specific process problems diagnosed by the system.

Development of Methods and Equipment for Sheet Stamping

NASA Astrophysics Data System (ADS)

Botashev, A. Yu; Bisilov, N. U.; Malsugenov, R. S.

2018-03-01

New methods of sheet stamping were developed: the gas forming with double-sided heating of a blank part and the gas molding with backpressure. In case of the first method the blank part is heated to the set temperature by means of a double-sided impact of combustion products of gas mixtures, after which, under the influence of gas pressure a stamping process is performed. In case of gas molding with backpressure, the blank part is heated to the set temperature by one-sided impact of the combustion products, while backpressure is created on the opposite side of the blank part by compressed air. In both methods the deformation takes place in the temperature range of warm or hot treatment due to the heating of a blank part. This allows one to form parts of complicated shape within one technological operation, which significantly reduces the cost of production. To implement these methods, original devices were designed and produced, which are new types of forging and stamping equipment. Using these devices, an experimental research on the stamping process was carried out and high-quality parts were obtained, which makes it possible to recommend the developed methods of stamping in the industrial production. Their application in small-scale production will allow one to reduce the cost price of stamped parts 2 or 3 times.

Design and fabrication of label-free biochip using a guided mode resonance filter with nano grating structures by injection molding process.

PubMed

Cho, E; Kim, B; Choi, S; Han, J; Jin, J; Han, J; Lim, J; Heo, Y; Kim, S; Sung, G Y; Kang, S

2011-01-01

This paper introduces technology to fabricate a guided mode resonance filter biochip using injection molding. Of the various nanofabrication processes that exist, injection molding is the most suitable for the mass production of polymer nanostructures. Fabrication of a nanograting pattern for guided mode resonance filters by injection molding requires a durable metal stamp, because of the high injection temperature and pressure. Careful consideration of the optimized process parameters is also required to achieve uniform sub-wavelength gratings with high fidelity. In this study, a metallic nanostructure pattern to be used as the stamp for the injection molding process was fabricated using electron beam lithography, a UV nanoimprinting process, and an electroforming process. A one-dimensional nanograting substrate was replicated by injection molding, during which the process parameters were controlled. To evaluate the geometric quality of the injection molded nanograting patterns, the surface profile of the fabricated nanograting for different processing conditions was analyzed using an atomic force microscope and a scanning electron microscope. Finally, to demonstrate the feasibility of the proposed process for fabricating guided mode resonance filter biochips, a high-refractive-index material was deposited on the polymer nanograting and its guided mode resonance characteristics were analyzed.

MOLD-SPECIFIC QUANTITATIVE PCR: THE EMERGING STANDARD IN MOLD ANALYSIS

EPA Science Inventory

Molds can cause health problems like infections and allergies, destroy crops, and contaminate our food or pharmaceuticals. We can't avoid molds. Molds are essential players in the biological processes on earth, but we can now identify and quantify the molds that will be most pr...

Viscoelastic properties of chalcogenide glasses and the simulation of their molding processes

NASA Astrophysics Data System (ADS)

Liu, Weiguo; Shen, Ping; Jin, Na

In order to simulate the precision molding process, the viscoelastic properties of chalcogenide glasses under high temperatures were investigated. Thermomechanical analysis were performed to measure and analysis the thermomechanical properties of chalcogenide glasses. The creep responses of the glasses at different temperatures were obtained. Finite element analysis was applied for the simulation of the molding processes. The simulation results were in consistence with previously reported experiment results. Stress concentration and evolution during the molding processes was also described with the simulation results.

Optical clock signal distribution and packaging optimization

NASA Astrophysics Data System (ADS)

Wu, Linghui

Polymer-based waveguides for optoelectronic interconnects and packagings were fabricated by a fabrication process that is compatible with the Si CMOS packaging process. An optoelectronic interconnection layer (OIL) for the high-speed massive clock signal distribution for the Cray T-90 supercomputer board employing optical multimode channel waveguides in conjunction with surface-normal waveguide grating couplers and a 1-to-2 3 dB splitter was constructed. Equalized optical paths were realized using an optical H-tree structure having 48 optical fanouts. This device could be increased to 64 without introducing any additional complications. A 1-to-48 fanout H-tree structure using Ultradel 9000D series polyimide was fabricated. The propagation loss and splitting loss have been measured as 0.21 dB/cm and 0.4 dB/splitter at 850 nm. The power budget was discussed, and the H-tree waveguide fully satisfies the power budget requirement. A tapered waveguide coupler was employed to match the mode profile between the single-mode fiber and the multimode channel waveguides of the OIL. A thermo-optical based multimode switch was designed, fabricated, and tested. The finite difference method was used to simulate the thermal distribution in the polymer waveguide. Both stable and transient conditions have been calculated. The thermo-optical switch was fabricated and tested. The switching speed of 1 ms was experimentally confirmed, fitting well with the simulation results. Thermo-optic switching for randomly polarized light at wavelengths of 850 nm was experimental confirmed, as was a stable attenuation of 25 dB. The details of tapered waveguide fabrication were investigated. Compression-molded 3-D tapered waveguides were demonstrated for the first time. Not only the vertical depth variation but also the linear dimensions of the molded waveguides were well beyond the limits of what any other conventional waveguide fabrication method is capable of providing. Molded waveguides with vertical depths of 100 mum at one end and 5 mum at the other end and lengths of 1.0 cm were fabricated using a photolime gel polymer. A propagation loss of 0.5 dB/cm was achieved when light was coupled from the 5 mum x 5 mum end to the 100 mum x 100 mum end and that of 1.1 dB/cm was observed when light was coupled from the 100 mum x 100 mum end to the 5 mum x 5 mum. By confining the energy to the fundamental mode when coupling from the large end to the small end, low-loss packaging can be achieved bi-directionally. 3-D compression-molded polymeric waveguides present a promising solution to bridging the huge dynamic range of different optoelectronic device-depths varying from a few microns to several hundred microns.

Strength and fatigue properties of three-step sintered dense nanocrystal hydroxyapatite bioceramics

NASA Astrophysics Data System (ADS)

Guo, Wen-Guang; Qiu, Zhi-Ye; Cui, Han; Wang, Chang-Ming; Zhang, Xiao-Jun; Lee, In-Seop; Dong, Yu-Qi; Cui, Fu-Zhai

2013-06-01

Dense hydroxyapatite (HA) ceramic is a promising material for hard tissue repair due to its unique physical properties and biologic properties. However, the brittleness and low compressive strength of traditional HA ceramics limited their applications, because previous sintering methods produced HA ceramics with crystal sizes greater than nanometer range. In this study, nano-sized HA powder was employed to fabricate dense nanocrystal HA ceramic by high pressure molding, and followed by a three-step sintering process. The phase composition, microstructure, crystal dimension and crystal shape of the sintered ceramic were examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Mechanical properties of the HA ceramic were tested, and cytocompatibility was evaluated. The phase of the sintered ceramic was pure HA, and the crystal size was about 200 nm. The compressive strength and elastic modulus of the HA ceramic were comparable to human cortical bone, especially the good fatigue strength overcame brittleness of traditional sintered HA ceramics. Cell attachment experiment also demonstrated that the ceramics had a good cytocompatibility.

Improved molding process ensures plastic parts of higher tensile strength

NASA Technical Reports Server (NTRS)

Heier, W. C.

1968-01-01

Single molding process ensures that plastic parts /of a given mechanical design/ produced from a conventional thermosetting molding compound will have a maximum tensile strength. The process can also be used for other thermosetting compounds to produce parts with improved physical properties.

Nonisothermal glass molding for the cost-efficient production of precision freeform optics

NASA Astrophysics Data System (ADS)

Vu, Anh-Tuan; Kreilkamp, Holger; Dambon, Olaf; Klocke, Fritz

2016-07-01

Glass molding has become a key replication-based technology to satisfy intensively growing demands of complex precision optics in the today's photonic market. However, the state-of-the-art replicative technologies are still limited, mainly due to their insufficiency to meet the requirements of mass production. This paper introduces a newly developed nonisothermal glass molding in which a complex-shaped optic is produced in a very short process cycle. The innovative molding technology promises a cost-efficient production because of increased mold lifetime, less energy consumption, and high throughput from a fast process chain. At the early stage of the process development, the research focuses on an integration of finite element simulation into the process chain to reduce time and labor-intensive cost. By virtue of numerical modeling, defects including chill ripples and glass sticking in the nonisothermal molding process can be predicted and the consequent effects are avoided. In addition, the influences of process parameters and glass preforms on the surface quality, form accuracy, and residual stress are discussed. A series of experiments was carried out to validate the simulation results. The successful modeling, therefore, provides a systematic strategy for glass preform design, mold compensation, and optimization of the process parameters. In conclusion, the integration of simulation into the entire nonisothermal glass molding process chain will significantly increase the manufacturing efficiency as well as reduce the time-to-market for the mass production of complex precision yet low-cost glass optics.

Accelerated aging studies of UHMWPE. I. Effect of resin, processing, and radiation environment on resistance to mechanical degradation.

PubMed

Edidin, A A; Herr, M P; Villarraga, M L; Muth, J; Yau, S S; Kurtz, S M

2002-08-01

The resin and processing route have been identified as potential variables influencing the mechanical behavior, and hence the clinical performance, of ultra-high molecular weight polyethylene (UHMWPE) orthopedic components. Researchers have reported that components fabricated from 1900 resin may oxidize to a lesser extent than components fabricated from GUR resin during shelf aging after gamma sterilization in air. Conflicting reports on the oxidation resistance for 1900 raise the question of whether resin or manufacturing method, or an interaction between resin and manufacturing method, influences the mechanical behavior of UHMWPE. We conducted a series of accelerated aging studies (no aging, aging in oxygen or in nitrogen) to systematically examine the influence of resin (GUR or 1900), manufacturing method (bulk compression molding or extrusion), and sterilization method (none, in air, or in nitrogen) on the mechanical behavior of UHMWPE. The small punch testing technique was used to evaluate the mechanical behavior of the materials, and Fourier transform infrared spectroscopy was used to characterize the oxidation in selected samples. Our study showed that the sterilization environment, aging condition, and specimen location (surface or subsurface) significantly affected the mechanical behavior of UHMWPE. Each of the three polyethylenes evaluated seem to degrade according to a similar pathway after artificial aging in oxygen and gamma irradiation in air. The initial ability of the materials to exhibit post-yield strain hardening was significantly compromised by degradation. In general, there were only minor differences in the aging behavior of molded and extruded GUR 1050, whereas the molded 1900 material seemed to degrade slightly faster than either of the 1050 materials. Copyright 2002 Wiley Periodicals, Inc.

Investigation of micro-injection molding based on longitudinal ultrasonic vibration core.

PubMed

Qiu, Zhongjun; Yang, Xue; Zheng, Hui; Gao, Shan; Fang, Fengzhou

2015-10-01

An ultrasound-assisted micro-injection molding method is proposed to improve the rheological behavior of the polymer melt radically, and a micro-injection molding system based on a longitudinal ultrasonic vibration core is developed and employed in the micro-injection molding process of Fresnel lenses. The verification experiments show that the filling mold area of the polymer melt is increased by 6.08% to 19.12%, and the symmetric deviation of the Fresnel lens is improved 15.62% on average. This method improved the filling performance and replication quality of the polymer melt in the injection molding process effectively.

Dynamic Feed Control For Injection Molding

DOEpatents

Kazmer, David O.

1996-09-17

The invention provides methods and apparatus in which mold material flows through a gate into a mold cavity that defines the shape of a desired part. An adjustable valve is provided that is operable to change dynamically the effective size of the gate to control the flow of mold material through the gate. The valve is adjustable while the mold material is flowing through the gate into the mold cavity. A sensor is provided for sensing a process condition while the part is being molded. During molding, the valve is adjusted based at least in part on information from the sensor. In the preferred embodiment, the adjustable valve is controlled by a digital computer, which includes circuitry for acquiring data from the sensor, processing circuitry for computing a desired position of the valve based on the data from the sensor and a control data file containing target process conditions, and control circuitry for generating signals to control a valve driver to adjust the position of the valve. More complex embodiments include a plurality of gates, sensors, and controllable valves. Each valve is individually controllable so that process conditions corresponding to each gate can be adjusted independently. This allows for great flexibility in the control of injection molding to produce complex, high-quality parts.

Feasibility of using Big Area Additive Manufacturing to Directly Manufacture Boat Molds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Post, Brian K.; Chesser, Phillip C.; Lind, Randall F.

The goal of this project was to explore the feasibility of using Big Area Additive Manufacturing (BAAM) to directly manufacture a boat mold without the need for coatings. All prior tooling projects with BAAM required the use to thick coatings to overcome the surface finish limitations of the BAAM process. While the BAAM process significantly lowers the cost of building the mold, the high cost element rapidly became the coatings (cost of the material, labor on coating, and finishing). As an example, the time and cost to manufacture the molds for the Wind Turbine project with TPI Composites Inc. andmore » the molds for the submarine project with Carderock Naval Warfare Systems was a fraction of the time and cost of the coatings. For this project, a catamaran boat hull mold was designed, manufactured, and assembled with an additional 0.15” thickness of material on all mold surfaces. After printing, the mold was immediately machined and assembled. Alliance MG, LLC (AMG), the industry partner of this project, experimented with mold release agents on the carbon-fiber reinforced acrylonitrile butadiene styrene (CF ABS) to verify that the material can be directly used as a mold (rather than needing a coating). In addition, for large molds (such as the wind turbine mold with TPI Composites Inc.), the mold only provided the target surface. A steel subframe had to be manufactured to provide structural integrity. If successful, this will significantly reduce the time and cost necessary for manufacturing large resin infusion molds using the BAAM process.« less

Residual thermal stresses in a solid sphere cast from a thermosetting material

NASA Technical Reports Server (NTRS)

Levitsky, M.; Shaffer, B. W.

1975-01-01

Expressions are developed for the residual thermal stresses in a solid sphere cast from a chemically hardening thermosetting material in a rigid spherical mold. The description of the heat generation rate and temperature variation is derived from a first-order chemical reaction. Solidification is described by the continuous transformation of the material from an inviscid liquidlike state into an elastic solid, with intermediate properties determined by the degree of chemical reaction. Residual stress components are obtained as functions of the parameters of the hardening process and the properties of the hardening material. Variation of the residual stresses with a nondimensionalized reaction rate parameter and the relative compressibility of the hardened material is discussed in detail.

Dimensional Precision Research of Wax Molding Rapid Prototyping based on Droplet Injection

NASA Astrophysics Data System (ADS)

Mingji, Huang; Geng, Wu; yan, Shan

2017-11-01

The traditional casting process is complex, the mold is essential products, mold quality directly affect the quality of the product. With the method of rapid prototyping 3D printing to produce mold prototype. The utility wax model has the advantages of high speed, low cost and complex structure. Using the orthogonal experiment as the main method, analysis each factors of size precision. The purpose is to obtain the optimal process parameters, to improve the dimensional accuracy of production based on droplet injection molding.

Improved silicon carbide for advanced heat engines. I - Process development for injection molding

NASA Technical Reports Server (NTRS)

Whalen, Thomas J.; Trela, Walter

1989-01-01

Alternate processing methods have been investigated as a means of improving the mechanical properties of injection-molded SiC. Various mixing processes (dry, high-sheer, and fluid) were evaluated along with the morphology and particle size of the starting beta-SiC powder. Statistically-designed experiments were used to determine significant effects and interactions of variables in the mixing, injection molding, and binder removal process steps. Improvements in mechanical strength can be correlated with the reduction in flaw size observed in the injection molded green bodies obtained with improved processing methods.

Implementation of Statistical Process Control: Evaluating the Mechanical Performance of a Candidate Silicone Elastomer Docking Seal

NASA Technical Reports Server (NTRS)

Oravec, Heather Ann; Daniels, Christopher C.

2014-01-01

The National Aeronautics and Space Administration has been developing a novel docking system to meet the requirements of future exploration missions to low-Earth orbit and beyond. A dynamic gas pressure seal is located at the main interface between the active and passive mating components of the new docking system. This seal is designed to operate in the harsh space environment, but is also to perform within strict loading requirements while maintaining an acceptable level of leak rate. In this study, a candidate silicone elastomer seal was designed, and multiple subscale test articles were manufactured for evaluation purposes. The force required to fully compress each test article at room temperature was quantified and found to be below the maximum allowable load for the docking system. However, a significant amount of scatter was observed in the test results. Due to the stochastic nature of the mechanical performance of this candidate docking seal, a statistical process control technique was implemented to isolate unusual compression behavior from typical mechanical performance. The results of this statistical analysis indicated a lack of process control, suggesting a variation in the manufacturing phase of the process. Further investigation revealed that changes in the manufacturing molding process had occurred which may have influenced the mechanical performance of the seal. This knowledge improves the chance of this and future space seals to satisfy or exceed design specifications.

Contact Behavior of Composite CrTiSiN Coated Dies in Compressing of Mg Alloy Sheets under High Pressure

PubMed Central

Yang, T.S.; Yao, S.H.; Chang, Y.Y.; Deng, J.H.

2018-01-01

Hard coatings have been adopted in cutting and forming applications for nearly two decades. The major purpose of using hard coatings is to reduce the friction coefficient between contact surfaces, to increase strength, toughness and anti-wear performance of working tools and molds, and then to obtain a smooth work surface and an increase in service life of tools and molds. In this report, we deposited a composite CrTiSiN hard coating, and a traditional single-layered TiAlN coating as a reference. Then, the coatings were comparatively studied by a series of tests. A field emission SEM was used to characterize the microstructure. Hardness was measured using a nano-indentation tester. Adhesion of coatings was evaluated using a Rockwell C hardness indentation tester. A pin-on-disk wear tester with WC balls as sliding counterparts was used to determine the wear properties. A self-designed compression and friction tester, by combining a Universal Testing Machine and a wear tester, was used to evaluate the contact behavior of composite CrTiSiN coated dies in compressing of Mg alloy sheets under high pressure. The results indicated that the hardness of composite CrTiSiN coating was lower than that of the TiAlN coating. However, the CrTiSiN coating showed better anti-wear performance. The CrTiSiN coated dies achieved smooth surfaces on the Mg alloy sheet in the compressing test and lower friction coefficient in the friction test, as compared with the TiAlN coating. PMID:29316687

Contact Behavior of Composite CrTiSiN Coated Dies in Compressing of Mg Alloy Sheets under High Pressure.

PubMed

Yang, T S; Yao, S H; Chang, Y Y; Deng, J H

2018-01-08

Hard coatings have been adopted in cutting and forming applications for nearly two decades. The major purpose of using hard coatings is to reduce the friction coefficient between contact surfaces, to increase strength, toughness and anti-wear performance of working tools and molds, and then to obtain a smooth work surface and an increase in service life of tools and molds. In this report, we deposited a composite CrTiSiN hard coating, and a traditional single-layered TiAlN coating as a reference. Then, the coatings were comparatively studied by a series of tests. A field emission SEM was used to characterize the microstructure. Hardness was measured using a nano-indentation tester. Adhesion of coatings was evaluated using a Rockwell C hardness indentation tester. A pin-on-disk wear tester with WC balls as sliding counterparts was used to determine the wear properties. A self-designed compression and friction tester, by combining a Universal Testing Machine and a wear tester, was used to evaluate the contact behavior of composite CrTiSiN coated dies in compressing of Mg alloy sheets under high pressure. The results indicated that the hardness of composite CrTiSiN coating was lower than that of the TiAlN coating. However, the CrTiSiN coating showed better anti-wear performance. The CrTiSiN coated dies achieved smooth surfaces on the Mg alloy sheet in the compressing test and lower friction coefficient in the friction test, as compared with the TiAlN coating.

Composite hub/metal blade compressor rotor

NASA Technical Reports Server (NTRS)

Yao, S.

1978-01-01

A low cost compressor rotor was designed and fabricated for a small jet engine. The rotor hub and blade keepers were compression molded with graphite epoxy. Each pair of metallic blades was held in the hub by a keeper. All keepers were locked in the hub with circumferential windings. Feasibility of fabrication was demonstrated in this program.

Response of resin transfer molded (RTM) composites under reversed cyclic loading

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mahfuz, H.; Haque, A.; Yu, D.

1996-01-01

Compressive behavior and the tension-compression fatigue response of resin transfer molded IM7 PW/PR 500 composite laminate with a circular notch have been studied. Fatigue damage characteristics have been investigated through the changes in the laminate strength and stiffness by gradually incrementing the fatigue cycles at a preselected load level. Progressive damage in the surface of the laminate during fatigue has been investigated using cellulose replicas. Failure mechanisms during static and cyclic tests have been identified and presented in detail. Extensive debonding of filaments and complete fiber bundle fracture accompanied by delamination were found to be responsible for fatigue failures, whilemore » fiber buckling, partial fiber fracture and delamination were characterized as the failure modes during static tests. Weibull analysis of the static, cyclic and residual tests have been performed and described in detail. Fractured as well as untested specimens were C-scanned, and the progressive damage growth during fatigue is presented. Optical Microscopy (OM) and Scanning Electron Microscopy (SEM) for the fractured specimen were also performed and the analysis of the failure behavior is presented.« less

Hydrogen silsesquioxane mold coatings for improved replication of nanopatterns by injection molding

NASA Astrophysics Data System (ADS)

Hobæk, Thor Christian; Matschuk, Maria; Kafka, Jan; Pranov, Henrik J.; Larsen, Niels B.

2015-03-01

We demonstrate the replication of nanosized pillars in polymer (cyclic olefin copolymer) by injection molding using nanostructured thermally cured hydrogen silsesquioxane (HSQ) ceramic coatings on stainless steel mold inserts with mold nanostructures produced by a simple embossing process. At isothermal mold conditions, the average pillar height increases by up to 100% and a more uniform height distribution is observed compared to a traditional metal mold insert. Thermal heat transfer simulations predict that the HSQ film retards the cooling of the polymer melt during the initial stages of replication, thus allowing more time to fill the nanoscale cavities compared to standard metal molds. A monolayer of a fluorinated silane (heptadecafluorotrichlorosilane) deposited on the mold surface reduces the mold/polymer interfacial energy to support demolding of the polymer replica. The mechanical stability of thermally cured HSQ makes it a promising material for nanopattern replication on an industrial scale without the need for slow and energy intensive variotherm processes.

Real-time parameter optimization based on neural network for smart injection molding

NASA Astrophysics Data System (ADS)

Lee, H.; Liau, Y.; Ryu, K.

2018-03-01

The manufacturing industry has been facing several challenges, including sustainability, performance and quality of production. Manufacturers attempt to enhance the competitiveness of companies by implementing CPS (Cyber-Physical Systems) through the convergence of IoT(Internet of Things) and ICT(Information & Communication Technology) in the manufacturing process level. Injection molding process has a short cycle time and high productivity. This features have been making it suitable for mass production. In addition, this process is used to produce precise parts in various industry fields such as automobiles, optics and medical devices. Injection molding process has a mixture of discrete and continuous variables. In order to optimized the quality, variables that is generated in the injection molding process must be considered. Furthermore, Optimal parameter setting is time-consuming work to predict the optimum quality of the product. Since the process parameter cannot be easily corrected during the process execution. In this research, we propose a neural network based real-time process parameter optimization methodology that sets optimal process parameters by using mold data, molding machine data, and response data. This paper is expected to have academic contribution as a novel study of parameter optimization during production compare with pre - production parameter optimization in typical studies.

Process influences and correction possibilities for high precision injection molded freeform optics

NASA Astrophysics Data System (ADS)

Dick, Lars; Risse, Stefan; Tünnermann, Andreas

2016-08-01

Modern injection molding processes offer a cost-efficient method for manufacturing high precision plastic optics for high volume applications. Besides form deviation of molded freeform optics, internal material stress is a relevant influencing factor for the functionality of a freeform optics in an optical system. This paper illustrates dominant influence parameters of an injection molding process relating to form deviation and internal material stress based on a freeform demonstrator geometry. Furthermore, a deterministic and efficient way for 3D mold correcting of systematic, asymmetrical shrinkage errors is shown to reach micrometer range shape accuracy at diameters up to 40 mm. In a second case, a stress-optimized parameter combination using unusual molding conditions was 3D corrected to reach high precision and low stress freeform polymer optics.

Integrally cored ceramic investment casting mold fabricated by ceramic stereolithography

NASA Astrophysics Data System (ADS)

Bae, Chang-Jun

Superalloy airfoils are produced by investment casting (IC), which uses ceramic cores and wax patterns with ceramic shell molds. Hollow cored superalloy airfoils in a gas turbine engine are an example of complex IC parts. The complex internal hollow cavities of the airfoil are designed to conduct cooling air through one or more passageways. These complex internal passageways have been fabricated by a lost wax process requiring several processing steps; core preparation, injection molding for wax pattern, and dipping process for ceramic shell molds. Several steps generate problems such as high cost and decreased accuracy of the ceramic mold. For example, costly tooling and production delay are required to produce mold dies for complex cores and wax patterns used in injection molding, resulting in a big obstacle for prototypes and smaller production runs. Rather than using separate cores, patterns, and shell molds, it would be advantageous to directly produce a mold that has the casting cavity and the ceramic core by one process. Ceramic stereolithography (CerSLA) can be used to directly fabricate the integrally cored ceramic casting mold (ICCM). CerSLA builds ceramic green objects from CAD files from many thin liquid layers of powder in monomer, which are solidified by polymerization with a UV laser, thereby "writing" the design for each slice. This dissertation addresses the integrally cored casting ceramic mold (ICCM), the ceramic core with a ceramic mold shell in a single patternless construction, fabricated by ceramic stereolithography (CerSLA). CerSLA is considered as an alternative method to replace lost wax processes, for small production runs or designs too complex for conventional cores and patterns. The main topic is the development of methods to successfully fabricate an ICCM by CerSLA from refractory silica, as well as related issues. The related issues are the segregation of coarse fused silica powders in a layer, the degree of segregation parameter to prevent segregation, and sintering and cristobalite transformation in fused silica compacts.

Novel pre-alloyed powder processing of modified alnico 8: Correlation of microstructure and magnetic properties

DOE PAGES

Anderson, I. E.; Kassen, A. G.; White, E. M. H.; ...

2015-04-13

Progress is reviewed on development of an improved near-final bulk magnet fabrication process for alnico 8, as a non-rare earth permanent magnet with promise for sufficient energy density and coercivity for electric drive motors. This study showed that alnico bulk magnets in near-final shape can be made by simple compression molding from spherical high purity gas atomized pre-alloyed powder. Dwell time at peak sintering temperature (1250°C) greatly affected grain size of the resulting magnet alloys. This microstructure transformation was demonstrated to be useful for gaining partially aligned magnetic properties and boosting energy product. Furthermore, while a route to increased coercivitymore » was not identified by these experiments, manufacturability of bulk alnico magnet alloys in near-final shapes was demonstrated, permitting further processing and alloy modification experiments that can target higher coercivity and better control of grain anisotropy during grain growth.« less

Processing-microstructure relationships in thermotropic liquid crystalline polymers: Experimental and numerical modeling studies

NASA Astrophysics Data System (ADS)

Fang, Jun

Thermotropic liquid crystalline polymers (TLCPs) are a class of promising engineering materials for high-demanding structural applications. Their excellent mechanical properties are highly correlated to the underlying molecular orientation states, which may be affected by complex flow fields during melt processing. Thus, understanding and eventually predicting how processing flows impact molecular orientation is a critical step towards rational design work in order to achieve favorable, balanced physical properties in finished products. This thesis aims to develop deeper understanding of orientation development in commercial TLCPs during processing by coordinating extensive experimental measurements with numerical computations. In situ measurements of orientation development of LCPs during processing are a focal point of this thesis. An x-ray capable injection molding apparatus is enhanced and utilized for time-resolved measurements of orientation development in multiple commercial TLCPs during injection molding. Ex situ wide angle x-ray scattering is also employed for more thorough characterization of molecular orientation distributions in molded plaques. Incompletely injection molded plaques ("short shots") are studied to gain further insights into the intermediate orientation states during mold filling. Finally, two surface orientation characterization techniques, near edge x-ray absorption fine structure (NEXAFS) and infrared attenuated total reflectance (FTIR-ATR) are combined to investigate the surface orientation distribution of injection molded plaques. Surface orientation states are found to be vastly different from their bulk counterparts due to different kinematics involved in mold filling. In general, complex distributions of orientation in molded plaques reflect the spatially varying competition between shear and extension during mold filling. To complement these experimental measurements, numerical calculations based on the Larson-Doi polydomain model are performed. The implementation of the Larson-Doi in complex processing flows is performed using a commercial process modeling software suite (MOLDFLOWRTM), exploiting a nearly exact analogy between the Larson-Doi model and a fiber orientation model that has been widely used in composites processing simulations. The modeling scheme is first verified by predicting many qualitative and quantitative features of molecular orientation distributions in isothermal extrusion-fed channel flows. In coordination with experiments, the model predictions are found to capture many qualitative features observed in injection molded plaques (including short shots). The final, stringent test of Larson-Doi model performance is prediction of in situ transient orientation data collected during mold filling. The model yields satisfactory results, though certain numerical approximations limit performance near the mold front.

Study on In-mold Punching during PPS/GF Injection Molding

NASA Astrophysics Data System (ADS)

Inuzuka, Takayuki; Fujita, Akihiro; Nakai, Asami; Hamada, Hiroyuki

The influence of the punching condition on strength and the amount of shear droop was investigated to optimize the processing condition for punching in the mold during glass fiber reinforced polyphenylenesulfide (PPS/GF) injection molding. For in-mold punching part during cooling process, the tensile strength was constant because the pressure loss by the punch did not occur. The amount of the shear droop decreased in line with the increase in delay time because the rigidity of injection molded part in the mold increased when the resin was cooled. Moreover, when the resin temperature lowered more than the glass transition temperature, the amount of the shear droop was constant because the rigidity became constant. It is necessary to begin punching when the resin temperature lowers more than the glass transition temperature after holding pressure process is completed, to secure high strength and to assume 0.05 mm or less, at which level the shear droop cannot be visually recognized. The shortest delay time for PPS/GF is 8 sec. The delay time to minimize the amount of the shear droop can be guessed by analyzing the temperature change of the resin in the mold by injection molding CAE.

Digital Twin concept for smart injection molding

NASA Astrophysics Data System (ADS)

Liau, Y.; Lee, H.; Ryu, K.

2018-03-01

Injection molding industry has evolved over decades and became the most common method to manufacture plastic parts. Monitoring and improvement in the injection molding industry are usually performed separately in each stage, i.e. mold design, mold making and injection molding process. However, in order to make a breakthrough and survive in the industrial revolution, all the stages in injection molding need to be linked and communicated with each other. Any changes in one stage will cause a certain effect in other stage because there is a correlation between each other. Hence, the simulation should not only based on the input of historical data, but it also needs to include the current condition of equipment and prediction of future events in other stages to make the responsive decision. This can be achieved by implementing the concept of Digital Twin that models the entire process as a virtual model and enables bidirectional control with the physical process. This paper presented types of data and technology required to build the Digital Twin for the injection molding industry. The concept includes Digital Twin of each stage and integration of these Digital Twin model as a thoroughgoing model of the injection molding industry.

Applications of nanocomposites and woodfiber plastics for microcellular injection molding

Treesearch

Lih-Sheng Turng; Mingjun Yuan; Hrishikesh Kharbas; Herman Winata; Daniel F. Caulfield

2003-01-01

The paper reviews the processing advantages and challenges of microcellular injection molding and presents recent research results on applications of nanocomposites and woodfiber-plastic composites as well as new process develop for the microcellular injection molding process. In particular, two types of polyamide (PA-6) neat resins and their filled counterparts, such...

Applications of thin carbon coatings and films in injection molding

NASA Astrophysics Data System (ADS)

Cabrera, Eusebio Duarte

In this research, the technical feasibility of two novel applications of thin carbon coatings is demonstrated. The first application consists of using thin carbon coatings on molds for molding ultra-thin plastic parts (<0.5 mm thickness) with lower pressures by promoting wall slip. The second application consists of a new approach to provide electromagnetic interference (EMI) shielding for plastic parts using in mold coated nanoparticle thin films or nanopapers to create a conductive top layer. During this research, the technical feasibility of a new approach was proven which provides injection molding of ultra-thin parts at lower pressures, without the need of fast heating/fast cooling or other expensive mold modification. An in-house developed procedure by other members of our group, was employed for coating the mold surface using chemical vapor deposition (CVD) resulting in a graphene coating with carbide bonding to the mold surface. The coating resulted in a significant decrease of surface friction and consequently easiness of flow when compared to their uncoated counterparts. Thermoplastic polymers and their composites are a very attractive alternative but are hindered by the non-conductive nature of polymers. There are two general approaches used to date to achieve EMI shielding for plastic products. One is to spray a conductive metal coating onto the plastic surface forming a layer that must maintain its shielding effectiveness (SE), and its adhesion to the plastic throughout the expected life of the product. However, metal coatings add undesirable weight and tend to corrode over time. Furthermore, scratching the coating may create shielding failure; therefore, a protective topcoat may be required. The other approach is to use polymer composites filled with conductive fillers such as carbon black (CB), carbon nanofiber (CNF), and carbon nanotube (CNT). While conductive fillers may increase the electrical conductivity of polymer composites, the loading of such fillers often cannot reach a high level (<10 wt. %) due to the dispersion difficulty and exponential increase in viscosity. In this research, the technical feasibility of a new approach to EMI shielding of plastic parts was proven using in mold coated nanoparticle thin films or nanopapers to create a conductive top layer. For many years, in-mold coating (IMC) has been commercially applied to Sheet Molding Compound (SMC) compression molded parts, as an environmentally friendly approach to improve its surface quality and provide the required conductivity for electrostatic painting using carbon black (CB). Such process can also be applied to injection molding for creating a top conductive layer. Increasing the amount of CB will increase the surface conductivity of the coated part, thus improving the paint transfer efficiency. However the CB levels needed to achieve the conductivity levels required for achieving EMI shielding would make the coating viscosity too large for proper coating. Nanopaper based composites are excellent candidates for EMI shielding because of the nanopaper's high concentration of carbon nanofibers (CNFs) (~2 wt% to 10 wt% depending on nanopaper/thermoplastic thickness and 71wt.% to 79wt.% in the nanopaper itself after resin infusion) and high conductivity of the nanopaper. Instead of premixing nanoparticles with IMC coating, nanopapers enable the use of low viscosity IMC without CB coating to impregnate the CNF network in order to reach high electrical conductivity and EMI shielding values. (Abstract shortened by UMI.).

Implications of diamond-turned versus diamond-ground mold fabrication techniques on precision-molded optics

NASA Astrophysics Data System (ADS)

Mertus, Lou; Symmons, Alan

2012-10-01

In recent years, the trend within the molded optics community has been an overall advancement in the capability to diamond grind molds using a variety of grinding techniques. Improvements in grinding equipment, materials and tooling have enabled higher quality ceramic and carbide molds and thereby lenses. Diamond turned molds from ductile metals are still used prevalently throughout the molding industry. Each technology presents a unique set of advantages and disadvantages whether used for precision injection molding of plastic optics or precision glass molding. This paper reviews the manufacturing techniques for each approach and applicable molding process. The advantages and disadvantages of each are compared and analyzed. The subtle differences that exist in optics molded from each technique and the impact they have on the performance in various applications is reviewed. Differences stemming from tooling material properties, material-specific minor defects, as well as cutting and grinding process-induced artifacts are described in detail as well as their influence on the roughness, waviness, and form errors present on the molded surface. A comparison with results between similar surfaces for both diamond grinding and diamond turning is presented.

Demonstration of pharmaceutical tablet coating process by injection molding technology.

PubMed

Puri, Vibha; Brancazio, David; Harinath, Eranda; Martinez, Alexander R; Desai, Parind M; Jensen, Keith D; Chun, Jung-Hoon; Braatz, Richard D; Myerson, Allan S; Trout, Bernhardt L

2018-01-15

We demonstrate the coating of tablets using an injection molding (IM) process that has advantage of being solvent free and can provide precision coat features. The selected core tablets comprising 10% w/w griseofulvin were prepared by an integrated hot melt extrusion-injection molding (HME-IM) process. Coating trials were conducted on a vertical injection mold machine. Polyethylene glycol and polyethylene oxide based hot melt extruded coat compositions were used. Tablet coating process feasibility was successfully demonstrated using different coating mold designs (with both overlapping and non-overlapping coatings at the weld) and coat thicknesses of 150 and 300 μm. The resultant coated tablets had acceptable appearance, seal at the weld, and immediate drug release profile (with an acceptable lag time). Since IM is a continuous process, this study opens opportunities to develop HME-IM continuous processes for transforming powder to coated tablets. Copyright © 2017 Elsevier B.V. All rights reserved.

Investigation of the adhesion interface obtained through two-component injection molding

NASA Astrophysics Data System (ADS)

Fetecau, Catalin; Stan, Felicia; Dobrea, Daniel

2011-01-01

In this paper we study the interface strength obtained through two-component (2C) injection molding of LDPE-HDPE polymers. First, numerical simulation of the over-molding process is carried out using Moldflow technology. Second, butt-joint specimens were produced by over-molding under different process condition, and tested. Two injection sequences were considered, injection of LDPE on HDPE polymer, and HDLE on LDPE, respectively. To investigate the effects of the mold surface roughness on the polymers adhesion at interface, different inserts with different roughness are employed.

Effects of process parameters on the molding quality of the micro-needle array

NASA Astrophysics Data System (ADS)

Qiu, Z. J.; Ma, Z.; Gao, S.

2016-07-01

Micro-needle array, which is used in medical applications, is a kind of typical injection molded products with microstructures. Due to its tiny micro-features size and high aspect ratios, it is more likely to produce short shots defects, leading to poor molding quality. The injection molding process of the micro-needle array was studied in this paper to find the effects of the process parameters on the molding quality of the micro-needle array and to provide theoretical guidance for practical production of high-quality products. With the shrinkage ratio and warpage of micro needles as the evaluation indices of the molding quality, the orthogonal experiment was conducted and the analysis of variance was carried out. According to the results, the contribution rates were calculated to determine the influence of various process parameters on molding quality. The single parameter method was used to analyse the main process parameter. It was found that the contribution rate of the holding pressure on shrinkage ratio and warpage reached 83.55% and 94.71% respectively, far higher than that of the other parameters. The study revealed that the holding pressure is the main factor which affects the molding quality of micro-needle array so that it should be focused on in order to obtain plastic parts with high quality in the practical production.

Residual stresses in injection molded shape memory polymer parts

NASA Astrophysics Data System (ADS)

Katmer, Sukran; Esen, Huseyin; Karatas, Cetin

2016-03-01

Shape memory polymers (SMPs) are materials which have shape memory effect (SME). SME is a property which has the ability to change shape when induced by a stimulator such as temperature, moisture, pH, electric current, magnetic field, light, etc. A process, known as programming, is applied to SMP parts in order to alter them from their permanent shape to their temporary shape. In this study we investigated effects of injection molding and programming processes on residual stresses in molded thermoplastic polyurethane shape memory polymer, experimentally. The residual stresses were measured by layer removal method. The study shows that injection molding and programming process conditions have significantly influence on residual stresses in molded shape memory polyurethane parts.

Process for slip casting textured tubular structures

DOEpatents

Steinlage, Greg A.; Trumble, Kevin P.; Bowman, Keith J.

2002-01-01

A process for centrifugal slip casting a textured hollow tube. A slip made up of a carrier fluid and a suspended powder is introduced into a porous mold which is rotated at a speed sufficient to create a centrifugal force that forces the slip radially outward toward the inner surface of the mold. The suspended powder, which is formed of particles having large dimensional aspect ratios such as particles of superconductive BSCCO, settles in a textured fashion radially outward toward the mold surface. The carrier fluid of the slip passes by capillary action radially outward around the settled particles and into the absorbent mold. A layer of mold release material is preferably centrifugally slip cast to cover the mold inner surface prior to the introduction of the BSCCO slip, and the mold release layer facilitates removal of the BSCCO greenbody from the mold without fracturing.

Replication of the nano-scale mold fabricated with focused ion beam

NASA Astrophysics Data System (ADS)

Gao, J. X.; Chan-Park, M. B.; Xie, D. Z.; Ngoi, Bryan K. A.

2004-12-01

Silicon mold fabricated with Focused Ion Beam lithography (FIB) was used to make silicone elastomer molds. The silicon mold is composed of lattice of holes which the diameter and depth are about 200 nm and 60 nm, respectively. The silicone elastomer material was then used to replicate slavery mold. Our study show the replication process with the elastomer mold had been performed successfully and the diameter of humps on the elastomer mold is near to that of holes on the master mold. But the height of humps in the elastomer mold is only 42 nm and it is different from the depth of holes in the master mold.

Precision lens molding of asphero diffractive surfaces in chalcogenide materials

NASA Astrophysics Data System (ADS)

Nelson, J.; Scordato, M.; Schwertz, K.; Bagwell, J.

2015-10-01

Finished lens molding, and the similar process of precision lens molding, have long been practiced for high volume, accurate replication of optical surfaces on oxide glass. The physics surrounding these processes are well understood, and the processes are capable of producing high quality optics with great fidelity. However, several limitations exist due to properties inherent with oxide glasses. Tooling materials that can withstand the severe environmental conditions of oxide glass molding cannot easily be machined to produce complex geometries such as diffractive surfaces, lens arrays, and off axis features. Current machining technologies coupled with a limited selection of tool materials greatly limits the type of structures that can be molded into the finished optic. Tooling for chalcogenide glasses are not bound by these restrictions since the molding temperatures required are much lower than for oxide glasses. Innovations in tooling materials and manufacturing techniques have enabled the production of complex geometries to optical quality specifications and have demonstrated the viability of creating tools for molding diffractive surfaces, off axis features, datums, and arrays. Applications for optics having these features are found in automotive, defense, security, medical, and industrial domains. This paper will discuss results achieved in the study of various molding techniques for the formation of positive diffractive features on a concave spherical surface molded from As2Se3 chalcogenide glass. Examples and results of molding with tools having CTE match with the glass and non CTE match will be reviewed. The formation of stress within the glass during molding will be discussed, and methods of stress management will also be demonstrated and discussed. Results of process development methods and production of good diffractive surfaces will be shown.

Microcellular nanocomposite injection molding process

Treesearch

Mingjun Yuan; Lih-Sheng Turng; Rick Spindler; Daniel Caulfield; Chris Hunt

2003-01-01

This study aims to explore the processing benefits and property improvements of combining nanocomposites with microcellular injection molding. The molded parts produced based on the Design of Experiments (DOE) matrices were subjected to tensile testing, impact testing, and Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), Dynamic Mechanical...

An experimental study on fracture mechanical behavior of rock-like materials containing two unparallel fissures under uniaxial compression

NASA Astrophysics Data System (ADS)

Huang, Yan-Hua; Yang, Sheng-Qi; Tian, Wen-Ling; Zeng, Wei; Yu, Li-Yuan

2016-06-01

Strength and deformability characteristics of rock with pre-existing fissures are governed by cracking behavior. To further research the effects of pre-existing fissures on the mechanical properties and crack coalescence process, a series of uniaxial compression tests were carried out for rock-like material with two unparallel fissures. In the present study, cement, quartz sand, and water were used to fabricate a kind of brittle rock-like material cylindrical model specimen. The mechanical properties of rock-like material specimen used in this research were all in good agreement with the brittle rock materials. Two unparallel fissures (a horizontal fissure and an inclined fissure) were created by inserting steel during molding the model specimen. Then all the pre-fissured rock-like specimens were tested under uniaxial compression by a rock mechanics servo-controlled testing system. The peak strength and Young's modulus of pre-fissured specimen all first decreased and then increased when the fissure angle increased from 0° to 75°. In order to investigate the crack initiation, propagation and coalescence process, photographic monitoring was adopted to capture images during the entire deformation process. Moreover, acoustic emission (AE) monitoring technique was also used to obtain the AE evolution characteristic of pre-fissured specimen. The relationship between axial stress, AE events, and the crack coalescence process was set up: when a new crack was initiated or a crack coalescence occurred, the corresponding axial stress dropped in the axial stress-time curve and a big AE event could be observed simultaneously. Finally, the mechanism of crack propagation under microscopic observation was discussed. These experimental results are expected to increase the understanding of the strength failure behavior and the cracking mechanism of rock containing unparallel fissures.

An in-mold packaging process for plastic fluidic devices.

PubMed

Yoo, Y E; Lee, K H; Je, T J; Choi, D S; Kim, S K

2011-01-01

Micro or nanofluidic devices have many channel shapes to deliver chemical solutions, body fluids or any fluids. The channels in these devices should be covered to prevent the fluids from overflowing or leaking. A typical method to fabricate an enclosed channel is to bond or weld a cover plate to a channel plate. This solid-to-solid bonding process, however, takes a considerable amount of time for mass production. In this study, a new process for molding a cover layer that can enclose open micro or nanochannels without solid-to-solid bonding is proposed and its feasibility is estimated. First, based on the design of a model microchannel, a brass microchannel master core was machined and a plastic microchannel platform was injection-molded. Using this molded platform, a series of experiments was performed for four process or mold design parameters. Some feasible conditions were successfully found to enclosed channels without filling the microchannels for the injection molding of a cover layer over the plastic microchannel platform. In addition, the bond strength and seal performance were estimated in a comparison with those done by conventional bonding or welding processes.

Characterization of hydroxyapatite whisker reinforced composites and scaffolds for mechanical and biological function in orthopaedic and spinal implants

NASA Astrophysics Data System (ADS)

Conrad, Timothy L.

The overall objective of this study was to investigate the mechanical and biological properties of HA whisker reinforced polyaryletherketone (PAEK) composites and scaffolds which are key to clinical translation for orthopedic and spinal implants. The fatigue behavior of polyetherketoneketone (PEKK) reinforced with 0, 20, and 40 vol% hydroxyapatite (HA) was investigated in four-point bending fatigue. The fatigue life decreased with increasing HA reinforcement. However, PEKK reinforced with 40 vol% HA whiskers exhibited a fatigue life greater than 2.106 cycles at 40 MPa. Moreover, HA whisker reinforcement resulted in decreased creep deformation and minimal modulus degradation. The effects of the mold temperature and polyetheretherketone (PEEK) powder were investigated on the mechanical properties and crystallinity of HA whisker reinforced PEEK scaffolds prepared using compression molding and porogen leaching. The mechanical properties of the scaffolds increased while the PEEK crystallinity decreased, with increasing mold temperature and suggested an optimal mold temperature of 370--375°C for PEEK scaffolds comprising of 75% porosity and 20 vol% HA whisker reinforcement, regardless of the PEEK powder size. The effects of the porogen morphology on the architecture, mechanical properties, and permeability of HA whisker reinforced PEEK scaffolds were investigated in 75--90% porous scaffolds. HA whisker reinforced PEEK scaffolds prepared with an ellipsoidal porogen exhibited a greater permeability than scaffolds prepared with a cubic porogen. The compressive modulus, yield strength, and yield strain were not affected by the porogen morphology. The effects of HA reinforcement morphology and content was investigated on the behavior of primary osteoblasts on dense HA reinforced PEEK substrates in vitro. At day 7, the number of osteoblasts attached to PEEK substrate surfaces increased with increasing HA content and for HA whiskers compared to equiaxed HA powder reinforcement. This suggests that the HA reinforcement content morphology can promote cellular attachment and proliferation at early time points.

Material flow data for numerical simulation of powder injection molding

NASA Astrophysics Data System (ADS)

Duretek, I.; Holzer, C.

2017-01-01

The powder injection molding (PIM) process is a cost efficient and important net-shape manufacturing process that is not completely understood. For the application of simulation programs for the powder injection molding process, apart from suitable physical models, exact material data and in particular knowledge of the flow behavior are essential in order to get precise numerical results. The flow processes of highly filled polymers are complex. Occurring effects are very hard to separate, like shear flow with yield stress, wall slip, elastic effects, etc. Furthermore, the occurrence of phase separation due to the multi-phase composition of compounds is quite probable. In this work, the flow behavior of a 316L stainless steel feedstock for powder injection molding was investigated. Additionally, the influence of pre-shearing on the flow behavior of PIM-feedstocks under practical conditions was examined and evaluated by a special PIM injection molding machine rheometer. In order to have a better understanding of key factors of PIM during the injection step, 3D non-isothermal numerical simulations were conducted with a commercial injection molding simulation software using experimental feedstock properties. The simulation results were compared with the experimental results. The mold filling studies amply illustrate the effect of mold temperature on the filling behavior during the mold filling stage. Moreover, the rheological measurements showed that at low shear rates no zero shear viscosity was observed, but instead the viscosity further increased strongly. This flow behavior could be described with the Cross-WLF approach with Herschel-Bulkley extension very well.

Applying simulation to optimize plastic molded optical parts

NASA Astrophysics Data System (ADS)

Jaworski, Matthew; Bakharev, Alexander; Costa, Franco; Friedl, Chris

2012-10-01

Optical injection molded parts are used in many different industries including electronics, consumer, medical and automotive due to their cost and performance advantages compared to alternative materials such as glass. The injection molding process, however, induces elastic (residual stress) and viscoelastic (flow orientation stress) deformation into the molded article which alters the material's refractive index to be anisotropic in different directions. Being able to predict and correct optical performance issues associated with birefringence early in the design phase is a huge competitive advantage. This paper reviews how to apply simulation analysis of the entire molding process to optimize manufacturability and part performance.

Conductivity fuel cell collector plate and method of fabrication

DOEpatents

Braun, James C.

2002-01-01

An improved method of manufacturing a PEM fuel cell collector plate is disclosed. During molding a highly conductive polymer composite is formed having a relatively high polymer concentration along its external surfaces. After molding the polymer rich layer is removed from the land areas by machining, grinding or similar process. This layer removal results in increased overall conductivity of the molded collector plate. The polymer rich surface remains in the collector plate channels, providing increased mechanical strength and other benefits to the channels. The improved method also permits greater mold cavity thickness providing a number of advantages during the molding process.

Crack Coalescence in Molded Gypsum and Carrara Marble

NASA Astrophysics Data System (ADS)

Wong, N.; Einstein, H. H.

2007-12-01

This research investigates the fracturing and coalescence behavior in prismatic laboratory-molded gypsum and Carrara marble specimens, which consist of either one or two pre-existing open flaws, under uniaxial compression. The tests are monitored by a high speed video system with a frame rate up to 24,000 frames/second. It allows one to precisely observe the cracking mechanisms, in particular if shear or tensile fracturing takes place. Seven crack types and nine crack coalescence categories are identified. The flaw inclination angle, the ligament length and the bridging angle between two flaws have different extents of influence on the coalescence patterns. For coplanar flaws, as the flaw inclination angle increases, there is a general trend of variation from shear coalescence to tensile coalescence. For stepped flaws, as the bridging angle changes from negative to small positive, and further up to large positive values, the coalescence generally progresses from categories of no coalescence, indirect coalescence to direct coalescence. For direct coalescence, it generally progresses from shear, mixed shear-tensile to tensile as the bridging angle increases. Some differences in fracturing and coalescence processes are observed in gypsum and marble, particularly the crack initiation in marble is preceded by the development of macroscopic white patches, but not in gypsum. Scanning Electron Microprobe (SEM) study reveals that the white patches consist of zones of microcracks (process zones).

Experimental analysis for fabrication of high-aspect-ratio piezoelectric ceramic structure by micro-powder injection molding process

NASA Astrophysics Data System (ADS)

Han, Jun Sae; Gal, Chang Woo; Park, Jae Man; Kim, Jong Hyun; Park, Seong Jin

2018-04-01

Aspect ratio effects in the micro-powder injection molding process were experimentally analyzed for fabrication of high-aspect-ratio piezoelectric ceramic structure. The mechanisms of critical defects have been studied according to individual manufacturing steps. In the molding process, incomplete filling phenomenon determines the critical aspect ratios of a micro pattern. According to mold temperature, an incomplete filling phenomenon has been analyzed with respect to different pattern sizes and aspect ratio. In demolding and drying process, the capillary behavior of sacrificial polymeric mold insert determines the critical aspect ratio of a micro pattern. With respect to pattern dimensions, slumping behavior has been analyzed. Based on our current systems, micro PZT feature has stability when it has lower aspect ratio than 5. Under optimized processing conditions, 20 μm and 40 μm ceramic rod array feature which has 5 of aspect ratio were successfully fabricated by the developed process. Further modification points to fabricate the smaller and higher feature were specifically addressed.

CAE for Injection Molding — Past, Present and the Future

NASA Astrophysics Data System (ADS)

Wang, Kuo K.

2004-06-01

It is well known that injection molding is the most effective process for mass-producing discrete plastic parts of complex shape to the highest precision at the lowest cost. However, due to the complex property of polymeric materials undergoing a transient non-isothermal process, it is equally well recognized that the quality of final products is often difficult to be assured. This is particularly true when a new mold or material is encountered. As a result, injection molding has often been viewed as an art than a science. During the past few decades, numerical simulation of injection molding process based on analytic models has become feasible for practical use as computers became faster and cheaper continually. A research effort was initiated at the Cornell Injection Molding Program (CIMP) in 1974 under a grant from the National Science Foundation. Over a quarter of the century, CIMP has established some scientific bases ranging from materials characterization, flow analysis, to prediction of part quality. Use of such CAE tools has become common place today in industry. Present effort has been primarily aimed at refinements of many aspects of the process. Computational efficiency and user-interface have been main thrusts by commercial software developers. Extension to 3-dimensional flow analysis for certain parts has drawn some attention. Research activities are continuing on molding of fiber-filled materials and reactive polymers. Expanded molding processes such as gas-assisted, co-injection, micro-molding and many others are continually being investigated. In the future, improvements in simulation accuracy and efficiency will continue. This will include in-depth studies on materials characterization. Intelligent on-line process control may draw more attention in order to achieve higher degree of automation. As Internet technology continues to evolve, Web-based CAE tools for design, production, remote process monitoring and control can come to path. The CAE tools will eventually be integrated into an Enterprise Resources Planning (ERP) system as the trend of enterprise globalization continues.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Tianyu; Xu, Hongyi; Chen, Wei

Fiber-reinforced polymer composites are strong candidates for structural materials to replace steel and light alloys in lightweight vehicle design because of their low density and relatively high strength. In the integrated computational materials engineering (ICME) development of carbon fiber composites, microstructure reconstruction algorithms are needed to generate material microstructure representative volume element (RVE) based on the material processing information. The microstructure RVE reconstruction enables the material property prediction by finite element analysis (FEA)This paper presents an algorithm to reconstruct the microstructure of a chopped carbon fiber/epoxy laminate material system produced by compression molding, normally known as sheet molding compounds (SMC).more » The algorithm takes the result from material’s manufacturing process as inputs, such as the orientation tensor of fibers, the chopped fiber sheet geometry, and the fiber volume fraction. The chopped fiber sheets are treated as deformable rectangle chips and a random packing algorithm is developed to pack these chips into a square plate. The RVE is built in a layer-by-layer fashion until the desired number of lamina is reached, then a fine tuning process is applied to finalize the reconstruction. Compared to the previous methods, this new approach has the ability to model bended fibers by allowing limited amount of overlaps of rectangle chips. Furthermore, the method does not need SMC microstructure images, for which the image-based characterization techniques have not been mature enough, as inputs. Case studies are performed and the results show that the statistics of the reconstructed microstructures generated by the algorithm matches well with the target input parameters from processing.« less

Use of overburden rocks from open-pit coal mines and waste coals of Western Siberia for ceramic brick production with a defect-free structure

NASA Astrophysics Data System (ADS)

Stolboushkin, A. Yu; Ivanov, A. I.; Storozhenko, G. I.; Syromyasov, V. A.; Akst, D. V.

2017-09-01

The rational technology for the production of ceramic bricks with a defect-free structure from coal mining and processing wastes was developed. The results of comparison of physical and mechanical properties and the structure of ceramic bricks manufactured from overburden rocks and waste coal with traditional for semi-dry pressing mass preparation and according to the developed method are given. It was established that a homogeneous, defect-free brick texture obtained from overburden rocks of open-pit mines and waste coal improves the quality of ceramic wall materials produced by the method of compression molding by more than 1.5 times compared to the brick with a traditional mass preparation.

Significant aspects on thermal degradation of hybrid biocomposite material

NASA Astrophysics Data System (ADS)

Bavan, D. Saravana; Kumar, G. C. Mohan

2013-06-01

Interest in use of bio fibers is increasing rapidly in structural and automotive applications because of few important properties such as low density, mechanical properties, renewability, biodegradation and sustainability. The present work is focused on fabricating a hybrid bio-composite material processed through compression molding technique. Natural fibers of maize and jute with bio polymeric resin of epoxidized soya bean oil are used as a matrix in obtaining a hybrid bio composite material. Thermal degradation of the prepared material is studied through Thermal gravimetric analyzer. Chemical treatment of the fibers was performed to have a better adhesion between the fibers and the matrix. The work is also surveyed on various parameters influencing the thermal properties and other aspects for a hybrid bio composite material.

Manufacture of mold of polymeric composite water pipe reinforced charcoal

NASA Astrophysics Data System (ADS)

Zulfikar; Misdawati; Idris, M.; Nasution, F. K.; Harahap, U. N.; Simanjuntak, R. K.; Jufrizal; Pranoto, S.

2018-03-01

In general, household wastewater pipelines currently use thermoplastic pipes of Polyvinyl Chloride (PVC). This material is known to be not high heat resistant, contains hazardous chemicals (toxins), relatively inhospitable, and relatively more expensive. Therefore, researchers make innovations utilizing natural materials in the form of wood charcoal as the basic material of making the water pipe. Making this pipe requires a simple mold design that can be worked in the scale of household and intermediate industries. This research aims to produce water pipe mold with simple design, easy to do, and making time relatively short. Some considerations for molding materials are weight of mold, ease of raw material, strong, sturdy, and able to cast. Pipe molds are grouped into 4 (four) main parts, including: outer diameter pipe molding, pipe inside diameter, pipe holder, and pipe alignment control. Some materials have been tested as raw materials for outer diameter of pipes, such as wood, iron / steel, cement, and thermoset. The best results are obtained on thermoset material, where the process of disassembling is easier and the resulting mold weight is relatively lighter. For the inside diameter of the pipe is used stainless steel, because in addition to be resistant to chemical processes that occur, in this part of the mold must hold the press load due to shrinkage of raw materials of the pipe during the process of hardening (polymerization). Therefore, it needs high pressure resistant material and does not blend with the raw material of the pipe. The base of the mold is made of stainless steel material because it must be resistant to corrosion due to chemical processes. As for the adjustment of the pipe is made of ST 37 carbon steel, because its function is only as a regulator of the alignment of the pipe structure.

Processing study of injection molding of silicon nitride for engine applications

NASA Technical Reports Server (NTRS)

Rorabaugh, M. E.; Yeh, H. C.

1985-01-01

The high hardness of silicon nitride, which is currently under consideration as a structural material for such hot engine components as turbine blades, renders machining of the material prohibitively costly; the near net shape forming technique of injection molding is accordingly favored as a means for component fabrication. Attention is presently given to the relationships between injection molding processing parameters and the resulting microstructural and mechanical properties of the resulting engine parts. An experimental program has been conducted under NASA sponsorship which tests the quality of injection molded bars of silicon nitride at various stages of processing.

Manufacturing plastic injection optical molds

NASA Astrophysics Data System (ADS)

Bourque, David

2008-08-01

ABCO Tool & Die, Inc. is a mold manufacturer specializing in the manufacturing of plastic injection molds for molded optical parts. The purpose of this presentation is to explain the concepts and procedures required to build a mold that produces precision optical parts. Optical molds can produce a variety of molded parts ranging from safety eyewear to sophisticated military lens parts, which must meet precise optical specifications. The manufacturing of these molds begins with the design engineering of precision optical components. The mold design and the related optical inserts are determined based upon the specific optical criteria and optical surface geometry. The mold manufacturing techniques will be based upon the optical surface geometry requirements and specific details. Manufacturing processes used will be specific to prescribed geometrical surface requirements of the molded part. The combined efforts result in a robust optical mold which can produce molded parts that meet the most precise optical specifications.

Graphite/epoxy composite stiffened panel fabrication development

NASA Technical Reports Server (NTRS)

Palmer, R. J.

1984-01-01

This report describes the manufacturing development procedures used to fabricate a series of carbon/epoxy panels with integrally molded stiffeners. Panel size was started at 6 inches by 18 inches and one stiffener and increased to 30 inches by 60 inches and six integral stiffeners. Stiffener concepts were optimized for minimum weight (or mass) to carry stress levels from 1500 lbs/inch to 25,000 lbs/inch compression load. Designs were created and manufactured with a stiffener configuration of integrally molded hat, J, I, sine wave I, solid blade, and honeycomb blade shapes. Successful and unsuccessful detail methods of tooling, lay-up methods, and bagging methods are documented. Recommendations are made for the best state-of-the-art manufacturing technique developed for type of stiffener construction.

Experimental and Numerical Analysis of Injection Molding of Ti-6Al-4V Powders for High-Performance Titanium Parts

NASA Astrophysics Data System (ADS)

Lin, Dongguo; Kang, Tae Gon; Han, Jun Sae; Park, Seong Jin; Chung, Seong Taek; Kwon, Young-Sam

2018-02-01

Both experimental and numerical analysis of powder injection molding (PIM) of Ti-6Al-4V alloy were performed to prepare a defect-free high-performance Ti-6Al-4V part with low carbon/oxygen contents. The prepared feedstock was characterized with specific experiments to identify its viscosity, pressure-volume-temperature and thermal properties to simulate its injection molding process. A finite-element-based numerical scheme was employed to simulate the thermomechanical process during the injection molding. In addition, the injection molding, debinding, sintering and hot isostatic pressing processes were performed in sequence to prepare the PIMed parts. With optimized processing conditions, the PIMed Ti-6Al-4V part exhibits excellent physical and mechanical properties, showing a final density of 99.8%, tensile strength of 973 MPa and elongation of 16%.

Development of stitched/RTM composite primary structures

NASA Technical Reports Server (NTRS)

Kullerd, Susan M.; Dow, Marvin B.

1992-01-01

The goal of the NASA Advanced Composites Technology (ACT) Program is to provide the technology required to gain the full benefit of weight savings and performance offered by composite primary structures. Achieving the goal is dependent on developing composite materials and structures which are damage tolerant and economical to manufacture. Researchers at NASA LaRC and Douglas Aircraft Company are investigating stitching reinforcement combined with resin transfer molding (RTM) to create structures meeting the ACT program goals. The Douglas work is being performed under a NASA contract entitled Innovative Composites Aircraft Primary Structures (ICAPS). The research is aimed at materials, processes and structural concepts for application in both transport wings and fuselages. Empirical guidelines are being established for stitching reinforcement in primary structures. New data are presented in this paper for evaluation tests of thick (90-ply) and thin (16-ply) stitched laminates, and from selection tests of RTM composite resins. Tension strength, compression strength and post-impact compression strength data are reported. Elements of a NASA LaRC program to expand the science base for stitched/RTM composites are discussed.

Automated catalyst processing for cloud electrode fabrication for fuel cells

DOEpatents

Goller, Glen J.; Breault, Richard D.

1980-01-01

A process for making dry carbon/polytetrafluoroethylene floc material, particularly useful in the manufacture of fuel cell electrodes, comprises of the steps of floccing a co-suspension of carbon particles and polytetrafluoroethylene particles, filtering excess liquids from the co-suspension, molding pellet shapes from the remaining wet floc solids without using significant pressure during the molding, drying the wet floc pellet shapes within the mold at temperatures no greater than about 150.degree. F., and removing the dry pellets from the mold.

The Effect of Epoxy Molding Compound Floor Life to Reliability Performance and mold ability for QFN Package

NASA Astrophysics Data System (ADS)

Peanpunga, Udom; Ugsornrat, Kessararat; Thorlor, Panakamol; Sumithpibul, Chalermsak

2017-09-01

This research studied about an epoxy molding compound (EMC) floor life to reliability performance of integrated circuit (IC) package. Molding is the process for protecting the die of IC package form mechanical and chemical reaction from external environment by shaping EMC. From normal manufacturing process, the EMC is stored in the frozen at 5oC and left at around room temperature for aging time or floor life before molding process. The EMC floor life effect to its properties and reliability performance of IC package. Therefore, this work interested in varied the floor life of EMC before molding process to analyze properties of EMC such as spiral flow length, gelation time, and viscosity. In experiment, the floor life of EMC was varied to check the effect of its property to reliability performance. The EMC floor life were varied from 0 hours to 60 hours with a step of 12 hours and observed wire sweep, incomplete EMC, and delamination inside the packages for 3x3, 5x5 and 8x8 mm2 of QFN packages. The evaluation showed about clearly effect of EMC floor life to IC packaging reliability. EMC floor life is not any concern for EMC property, moldabilty, and reliability from 0 hours to 48 hours for molding process of 3x3,5x5 and 8x8 mm2 QFN packaging manufacturing

Compression-Molding-Machine Tender (fabric. plastics prod.) 556.885--Technical Report on Development of USES Aptitude Test Battery.

ERIC Educational Resources Information Center

Manpower Administration (DOL), Washington, DC. U.S. Training and Employment Service.

The United States Training and Employment Service General Aptitude Test Battery (GATB), first published in 1947, has been included in a continuing program of research to validate the tests against success in many different occupations. The GATB consists of 12 tests which measure nine aptitudes: General Learning Ability; Verbal Aptitude; Numerical…

Fabrication of a Mechanically Robust Carbon Nanofiber Foam

DTIC Science & Technology

2015-06-01

Erlenmeyer exhaust trap utilizing zeolite and permanganate . ........................ 11   Figure 9.   Early CFF experimental mold...containing zeolite and permanganate to dilute the exhaust gases and trap unreacted ethylene prior to their release. Figure 7. MKS mass flow...controller (model MKS 647a). Figure 8. Erlenmeyer exhaust trap utilizing zeolite and permanganate . 12 c. Gas Mixture A flow of pure compressed

Effect of modified mold shell on the microstructure and tensile fracture morphology of single-crystal nickel-base superalloy

NASA Astrophysics Data System (ADS)

Xu, Weitai; Zhao, Yutao; Sun, Shaochun; Liu, Manping; Ma, Dexin; Liang, Xiangfeng; Wang, Cunlong; Tao, Ran

2018-04-01

The mold shell used for single-crystal turbine blades preparation was modified from conventional process to fiber reinforcement technology. The wall thickness was decreased by 32.3 percent (pct) than the conventional process. Then these two mold shells were used to produce single crystal samples of nickel-base superalloy in a Bridgman furnace. The local temperature curves were recorded in the process. The results show that the modified mold shell can increase the temperature gradient in the mushy zone than the conventional mold shell. The primary and secondary dendrite arm space were reduced by 8 pct and 12 pct, respectively. Moreover, both the area fraction and mean size of the γ‧/γ eutectic were declined, as well as the dendritic segregation tendency. Therefore it contributed to the lower residual eutectic and micro-porosity in the heat-treated microstructure. Further, fracture surface of the samples made by modified mold shell exhibited smaller facets and more uniform dimples in the size and shape.

An apparatus for in situ x-ray scattering measurements during polymer injection molding.

PubMed

Rendon, Stanley; Fang, Jun; Burghardt, Wesley R; Bubeck, Robert A

2009-04-01

We report a novel instrument for synchrotron-based in situ x-ray scattering measurements during injection molding processing. It allows direct, real-time monitoring of molecular-scale structural evolution in polymer materials undergoing a complex processing operation. The instrument is based on a laboratory-scale injection molding machine, and employs customized mold tools designed to allow x-ray access during mold filling and subsequent solidification, while providing sufficient robustness to withstand high injection pressures. The use of high energy, high flux synchrotron radiation, and a fast detector allows sufficiently rapid data acquisition to resolve time-dependent orientation dynamics in this transient process. Simultaneous monitoring of temperature and pressure signals allows transient scattering data to be referenced to various stages of the injection molding cycle. Representative data on a commercial liquid crystalline polymer, Vectra(R) B950, are presented to demonstrate the features of this apparatus; however, it may find application in a wide range of polymeric materials such as nanocomposites, semicrystalline polymers and fiber-reinforced thermoplastics.

Imidazole-based deep eutectic solvents for starch dissolution and plasticization.

PubMed

Zdanowicz, Magdalena; Spychaj, Tadeusz; Mąka, Honorata

2016-04-20

Potato starch and high-amylose starch were treated with imidazole-based deep eutectic solvents (DESs) as dissolution and plasticization media. Beside imidazole (IM) for two-component DESs preparation choline chloride (CC), glycerol (G) or carboxylic acids (citric or malic) were used. An influence of water content in starch (as well as an extra water in the starch/DES system) on polymer dissolution and plasticization processes was investigated. Dissolution and gelatinization of starch in DESs were followed via DSC and laser scanning microscopy. A rheometric characteristics revealed an influence of starch/DES system storage time on the plasticization process. The tendency to recrystallization of compression-molded-starch films was evaluated using XRD technique. High dissolution and plasticization effectiveness of CC/IM and G/IM and a low tendency to film retrogradation of thermoplasticized starch were noted. Copyright © 2015 Elsevier Ltd. All rights reserved.

Reversible TAD Chemistry as a Convenient Tool for the Design of (Re)processable PCL-Based Shape-Memory Materials.

PubMed

Defize, Thomas; Riva, Raphaël; Thomassin, Jean-Michel; Alexandre, Michaël; Herck, Niels Van; Prez, Filip Du; Jérôme, Christine

2017-01-01

A chemically cross-linked but remarkably (re)processable shape-memory polymer (SMP) is designed by cross-linking poly(ε-caprolactone) (PCL) stars via the efficient triazolinedione click chemistry, based on the very fast and reversible Alder-ene reaction of 1,2,4-triazoline-3,5-dione (TAD) with indole compounds. Typically, a six-arm star-shaped PCL functionalized by indole moieties at the chain ends is melt-blended with a bisfunctional TAD, directly resulting in a cross-linked PCL-based SMP without the need of post-curing treatment. As demonstrated by the stress relaxation measurement, the labile character of the TAD-indole adducts under stress allows for the solid-state plasticity reprocessing of the permanent shape at will by compression molding of the raw cross-linked material, while keeping excellent shape-memory properties. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Comparative study on the in vitro performance of blister molded and conventional lornoxicam immediate release liquitablets: accelerated stability study and anti-inflammatory and ulcerogenic effects.

PubMed

El-Setouhy, Doaa Ahmed; Gamiel, Alaa Abdel-Rahman; Badawi, Alia Abd El-Latif; Osman, Afaf Sayed; Labib, Dina Ahmed

2017-03-01

Lornoxicam is a potent non-steroidal anti-inflammatory drug (NSAID). It shows limited solubility in the gastric pH, delayed bioavailability and pharmacodynamic effects with aggravated gastric side effects (due to longer residence in the stomach wall). To enhance dissolution of lornoxicam in the gastric fluid and expectedly absorption and pharmacological action, with less ulcerogenic effects. Formulation of immediate release (IR) lornoxicam liquitablets containing both liquid and solid release modulators (wetting agent, solubilizers and microenvironmental pH modifiers). Beside the traditional direct compression technique employed for the preparation of liquitablets a new technique, blister molding, was also used. The effect of the two different manufacturing methods on the fast release characteristics (rapid disintegration and dissolution) was studied. Stability and pharmacological activity of the optimum formula were also explored. Similarity factor pointed out the superiority of molding technique in enhancing dissolution of lornoxicam owing to significant crystallinity reduction (XRD). Optimum formula showed negligible change in drug content and dissolution profiles over 12 weeks, significantly improved anti-inflammatory activity and significantly reduced gastric ulcerative effect over pure lornoxicam and commercial formula. Blister molded lornoxicam liquitablet of improved dissolution and pharmacological activity and less gastric erosion was successfully prepared.

Know your fibers : process and properties, or, a material science approach to designing pulp molded products

Treesearch

John F. Hunt

1998-01-01

The following results are preliminary, but show some basic information that will be used in an attempt to model pulp molded structures so that by measuring several basic fundamental properties of a fiber furnish and specifying process conditions, a molded structure could be designed for a particular performance need.

Virtual Manufacturing of Composite Structures for Ground Platforms, A DARPA Instant Foundry Adaptive Through Bits (iFAB) Program

DTIC Science & Technology

2012-08-01

This document contains color. 14. ABSTRACT This effort focused specifically on the Liquid Composite Molding (LCM) class of processes as they...SUBJECT TERMS Liquid Composite Molding (LCM), fabrication, manufacturability assessment 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF... Molding (LCM) .......................................................................... 2 1.1.1 LCM Process Variations

Flow behavior in liquid molding

NASA Technical Reports Server (NTRS)

Hunston, D.; Phelan, F.; Parnas, R.

1992-01-01

The liquid molding (LM) process for manufacturing polymer composites with structural properties has the potential to significantly lower fabrication costs and increase production rates. LM includes both resin transfer molding and structural reaction injection molding. To achieve this potential, however, the underlying science base must be improved to facilitate effective process optimization and implementation of on-line process control. The National Institute of Standards and Technology (NIST) has a major program in LM that includes materials characterization, process simulation models, on-line process monitoring and control, and the fabrication of test specimens. The results of this program are applied to real parts through cooperative projects with industry. The key feature in the effort is a comprehensive and integrated approach to the processing science aspects of LM. This paper briefly outlines the NIST program and uses several examples to illustrate the work.

Numerical prediction of flow induced fibers orientation in injection molded polymer composites

NASA Astrophysics Data System (ADS)

Oumer, A. N.; Hamidi, N. M.; Mat Sahat, I.

2015-12-01

Since the filling stage of injection molding process has important effect on the determination of the orientation state of the fibers, accurate analysis of the flow field for the mold filling stage becomes a necessity. The aim of the paper is to characterize the flow induced orientation state of short fibers in injection molding cavities. A dog-bone shaped model is considered for the simulation and experiment. The numerical model for determination of the fibers orientation during mold-filling stage of injection molding process was solved using Computational Fluid Dynamics (CFD) software called MoldFlow. Both the simulation and experimental results showed that two different regions (or three layers of orientation structures) across the thickness of the specimen could be found: a shell region which is near to the mold cavity wall, and a core region at the middle of the cross section. The simulation results support the experimental observations that for thin plates the probability of fiber alignment to the flow direction near the mold cavity walls is high but low at the core region. It is apparent that the results of this study could assist in decisions regarding short fiber reinforced polymer composites.

Investigation on the Effect of Mold Constraints and Cooling Rate on Residual Stress During the Sand-Casting Process of 1086 Steel by Employing a Thermomechanical Model

NASA Astrophysics Data System (ADS)

Baghani, Amir; Davami, Parviz; Varahram, Naser; Shabani, Mohsen Ostad

2014-06-01

In this study, the effects of mold constraints and cooling rate on residual stress were analyzed during the shaped casting process. For this purpose, an H-shaped sample was designed in which the contraction of its middle portion is highly restricted by the mold during the cooling process. The effects of an increasing cooling rate combined with mold constraints were analyzed by reducing the thickness of the middle portion in the second sample. A three-dimensional coupled temperature-displacement analysis was performed in finite-element code ABAQUS to simulate residual stress distribution, and then numerical results were verified by the hole-drilling strain-gauge method. It was concluded that the mold constraints have a greater effect on the values of residual stress than the cooling rate (thin section) in steel sand casting. Increasing the cooling rate would increase the amount of residual stress, only in the presence of mold constraints. It is also suggested that employing the elastic-plastic stress model for the sand mold will satisfy the experimental results and avoid exaggerated values of residual stress in simulation.

Predicting shrinkage and warpage in injection molding: Towards automatized mold design

NASA Astrophysics Data System (ADS)

Zwicke, Florian; Behr, Marek; Elgeti, Stefanie

2017-10-01

It is an inevitable part of any plastics molding process that the material undergoes some shrinkage during solidification. Mainly due to unavoidable inhomogeneities in the cooling process, the overall shrinkage cannot be assumed as homogeneous in all volumetric directions. The direct consequence is warpage. The accurate prediction of such shrinkage and warpage effects has been the subject of a considerable amount of research, but it is important to note that this behavior depends greatly on the type of material that is used as well as the process details. Without limiting ourselves to any specific properties of certain materials or process designs, we aim to develop a method for the automatized design of a mold cavity that will produce correctly shaped moldings after solidification. Essentially, this can be stated as a shape optimization problem, where the cavity shape is optimized to fulfill some objective function that measures defects in the molding shape. In order to be able to develop and evaluate such a method, we first require simulation methods for the diffierent steps involved in the injection molding process that can represent the phenomena responsible for shrinkage and warpage ina sufficiently accurate manner. As a starting point, we consider the solidification of purely amorphous materials. In this case, the material slowly transitions from fluid-like to solid-like behavior as it cools down. This behavior is modeled using adjusted viscoelastic material models. Once the material has passed a certain temperature threshold during cooling, any viscous effects are neglected and the behavior is assumed to be fully elastic. Non-linear elastic laws are used to predict shrinkage and warpage that occur after this point. We will present the current state of these simulation methods and show some first approaches towards optimizing the mold cavity shape based on these methods.

Influence of mold surface temperature on polymer part warpage in rapid heat cycle molding

NASA Astrophysics Data System (ADS)

Berger, G. R.; Pacher, G. A.; Pichler, A.; Friesenbichler, W.; Gruber, D. P.

2014-05-01

Dynamic mold surface temperature control was examined for its influence on the warpage. A test mold, featuring two different rapid heat cycle molding (RHCM) technologies was used to manufacture complex plate-shaped parts having different ribs, varying thin-wall regions, and both, circular and rectangular cut-outs. The mold's nozzle side is equipped with the areal heating and cooling technology BFMOLD®, where the heating/cooling channels are replaced by a ball-filled slot near the cavity surface flooded through with hot and cold water sequentially. Two local electrical ceramic heating elements are installed into the mold's ejection side. Based on a 23 full-factorial design of experiments (DoE) plan, varying nozzle temperature (Tnozzle), rapid heat cycle molding temperature (TRHCM) and holding pressure (pn), specimens of POM were manufactured systematically. Five specimens were examined per DoE run. The resulting warpage was measured at 6 surface line scans per part using the non-contact confocal topography system FRT MicroProf®. Two warpage parameters were calculated, the curvature of a 2nd order approximation a, and the vertical deflection at the profile center d. Both, the influence strength and the acting direction of the process parameters and their interactions on a and d were calculated by statistical analysis. Linear mathematical process models were determined for a and d to predict the warpage as a function of the process parameter settings. Finally, an optimum process setting was predicted, based on the process models and Microsoft Excel GRG solver. Clear and significant influences of TRHCM, pn, Tnozzle, and the interaction of TRHCM and pn were determined. While TRHCM was dominant close to the gate, pn became more effective as the flow length increased.

Injection molding of iPP samples in controlled conditions and resulting morphology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sessa, Nino, E-mail: ninosessa.ns@gmail.com; De Santis, Felice, E-mail: fedesantis@unisa.it; Pantani, Roberto, E-mail: rpantani@unisa.it

2015-12-17

Injection molded parts are driven down in size and weight especially for electronic applications. In this work, an investigation was carried out on the process of injection molding of thin iPP samples and on the morphology of these parts. Melt flow in the mold cavity was analyzed and described with a mathematical model. Influence of mold temperature and injection pressure was analyzed. Samples orientation was studied using optical microscopy.

Indirect three-dimensional printing of synthetic polymer scaffold based on thermal molding process.

PubMed

Park, Jeong Hun; Jung, Jin Woo; Kang, Hyun-Wook; Cho, Dong-Woo

2014-06-01

One of the major issues in tissue engineering has been the development of three-dimensional (3D) scaffolds, which serve as a structural template for cell growth and extracellular matrix formation. In scaffold-based tissue engineering, 3D printing (3DP) technology has been successfully applied for the fabrication of complex 3D scaffolds by using both direct and indirect techniques. In principle, direct 3DP techniques rely on the straightforward utilization of the final scaffold materials during the actual scaffold fabrication process. In contrast, indirect 3DP techniques use a negative mold based on a scaffold design, to which the desired biomaterial is cast and then sacrificed to obtain the final scaffold. Such indirect 3DP techniques generally impose a solvent-based process for scaffold fabrication, resulting in a considerable increase in the fabrication time and poor mechanical properties. In addition, the internal architecture of the resulting scaffold is affected by the properties of the biomaterial solution. In this study, we propose an advanced indirect 3DP technique using projection-based micro-stereolithography and an injection molding system (IMS) in order to address these challenges. The scaffold was fabricated by a thermal molding process using IMS to overcome the limitation of the solvent-based molding process in indirect 3DP techniques. The results indicate that the thermal molding process using an IMS has achieved a substantial reduction in scaffold fabrication time and has also provided the scaffold with higher mechanical modulus and strength. In addition, cell adhesion and proliferation studies have indicated no significant difference in cell activity between the scaffolds prepared by solvent-based and thermal molding processes.

Physical and mechanical properties of bio-composites from wood particles and liquefied wood resin

Treesearch

Hui Pan; Todd F. Shupe; Chung-Yun Hse

2009-01-01

Compression molded composites were made from wood particles and a liquefied wood/phenol/formaldehyde co-condensed resin. Based on our previous research, a phenol to wood (P/W) ratio of 2/1 was chosen for this study. The two experimental variables selected were: 1) liquefaction temperature (150o and 180oC) and 2) cooking method (atmospheric and sealed). Panels were...

Effect of Sericin on Mechanical Behavior of Composite Material Reinforced by Silk Woven Fabric

NASA Astrophysics Data System (ADS)

Kimura, Teruo; Ino, Haruhiro; Hanada, Koji; Katori, Sigetaka

Recent, attention has been given to shift from glass fibers and carbon fibers to natural fibers for FRP composites for the goal of protecting the environment. This paper concerned with the application of silk fabric for composite materials. Polypropylene (PP) was used for the matrix material and the silk fabric composites were molded using a compression molding method. Especially, the effect of sericin on mechanical behaviors of composite materials was discussed. Good adhesion between silk and PP was obtained by removing the sericin existing around the fibroin. The tensile modulus of composite decreased with decreasing the sericin because of the flexibility of silk fibers without sericin. In particular, the higher Izod impact value was obtained for the composites containing the silk fibers without sericin.

Interim Report on Mixing During the Casting of LEU-10Mo Plates in the Triple Plate Molds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aikin, Jr., Robert M.

LEU-10%Mo castings are commonly produced by down blending unalloyed HEU with a DU-12.7%Mo master-alloy. This work uses process modeling to provide insight into the mixing of the unalloyed uranium and U-Mo master alloy during melting and mold filling of a triple plate casting. Two different sets of situations are considered: (1) mixing during mold filling from a compositionally stratified crucible and (2) convective mixing of a compositionally stratified crucible during mold heating. The mold filling simulations are performed on the original Y-12 triple plate mold and the horizontal triple plate mold.

Fabrication Process for Large Size Mold and Alignment Method for Nanoimprint System

NASA Astrophysics Data System (ADS)

Ishibashi, Kentaro; Kokubo, Mitsunori; Goto, Hiroshi; Mizuno, Jun; Shoji, Shuichi

Nanoimprint technology is considered one of the mass production methods of the display for cellular phone or notebook computer, with Anti-Reflection Structures (ARS) pattern and so on. In this case, the large size mold with nanometer order pattern is very important. Then, we describe the fabrication process for large size mold, and the alignment method for UV nanoimprint system. We developed the original mold fabrication process using nanoimprint method and etching techniques. In 66 × 45 mm2 area, 200nm period seamless patterns were formed using this process. And, we constructed original alignment system that consists of the CCD-camera system, X-Y-θ table, method of moiré fringe, and image processing system, because the accuracy of pattern connection depends on the alignment method. This alignment system accuracy was within 20nm.

Determination of injection molding process windows for optical lenses using response surface methodology.

PubMed

Tsai, Kuo-Ming; Wang, He-Yi

2014-08-20

This study focuses on injection molding process window determination for obtaining optimal imaging optical properties, astigmatism, coma, and spherical aberration using plastic lenses. The Taguchi experimental method was first used to identify the optimized combination of parameters and significant factors affecting the imaging optical properties of the lens. Full factorial experiments were then implemented based on the significant factors to build the response surface models. The injection molding process windows for lenses with optimized optical properties were determined based on the surface models, and confirmation experiments were performed to verify their validity. The results indicated that the significant factors affecting the optical properties of lenses are mold temperature, melt temperature, and cooling time. According to experimental data for the significant factors, the oblique ovals for different optical properties on the injection molding process windows based on melt temperature and cooling time can be obtained using the curve fitting approach. The confirmation experiments revealed that the average errors for astigmatism, coma, and spherical aberration are 3.44%, 5.62%, and 5.69%, respectively. The results indicated that the process windows proposed are highly reliable.

Dense chitosan surgical membranes produced by a coincident compression-dehydration process

PubMed Central

Dooley, Thomas P.; Ellis, April L.; Belousova, Maria; Petersen, Don; DeCarlo, Arthur A.

2012-01-01

High density chitosan membranes were produced via a novel manufacturing process for use as implantable resorbable surgical membranes. The innovative method utilizes the following three sequential steps: (1) casting an acidic chitosan solution within a silicon mold, followed by freezing; (2) neutralizing the frozen acidic chitosan solution in alkaline solution to facilitate polymerization; and (3) applying coincident compression-dehydration under a vacuum. Resulting membranes of 0.2 – 0.5 mm thickness have densities as high as 1.6 g/cm3. Inclusion of glycerol prior to the compression-dehydration step provides additional physical and clinical handling benefits. The biomaterials exhibit tensile strength with a maximum load as high as 10.9 N at ~ 2.5 mm width and clinically-relevant resistance to suture pull-out with a maximum load as high as 2.2 N. These physical properties were superior to those of a commercial reconstituted collagen membrane. The dense chitosan membranes have excellent clinical handling characteristics, such as pliability and “memory” when wet. They are semi-permeable to small molecules, biodegradable in vitro in lysozyme solution, and the rates of degradation are inversely correlated to the degree of deacetylation. Furthermore, the dense chitosan membranes are biocompatible and resorbable in vivo as demonstrated in a rat oral wound healing model. The unique combination of physical, in vitro, in vivo, and clinical handling properties demonstrate the high utility of dense chitosan membranes produced by this new method. The materials may be useful as surgical barrier membranes, scaffolds for tissue engineering, wound dressings, and as delivery devices for active ingredients. PMID:23565872

Brittle Materials Design, High Temperature Gas Turbine

DTIC Science & Technology

1975-04-01

was directed toward fabricating flaw- free one-piece first stage stators using a silicon metal powder injection molding composition yielding reaction...process was used because this composition utilizes thermoset polymers which cannot be handled on available injection molding equipment. Silicon...molded of several compositions incorporating slight variations. Some of the components molded had completely filled the die cavity and appeared

Thermoplastics for aircraft interiors

NASA Technical Reports Server (NTRS)

Silverman, B.

1978-01-01

The goal for this contract is the development of processes and techniques for molding thermally stable, fire retardant, low smoke emitting polymeric materials. Outlined in this presentation are: (1) the typical molding types; (2) a program schedule; (3) physical properties of molding types with the test methods to be used; (4) general properties of injection molding materials; and (5) preliminary materials selection.

Laser micromilling of convex microfluidic channels onto glassy carbon for glass molding dies

NASA Astrophysics Data System (ADS)

Tseng, Shih-Feng; Chen, Ming-Fei; Hsiao, Wen-Tse; Huang, Chien-Yao; Yang, Chung-Heng; Chen, Yu-Sheng

2014-06-01

This study reports the fabrication of convex microfluidic channels on glassy carbon using an ultraviolet laser processing system to produce glass molding dies. The laser processing parameters, including various laser fluences and scanning speeds of galvanometers, were adjusted to mill a convex microchannel on a glassy carbon substrate to identify the effects of material removal. The machined glassy carbon substrate was then applied as a glass molding die to fabricate a glass-based microfluidic biochip. The surface morphology, milled width and depth, and surface roughness of the microchannel die after laser micromilling were examined using a three-dimensional confocal laser scanning microscope. This study also investigates the transcription rate of microchannels after the glass molding process. To produce a 180 μm high microchannel on the GC substrate, the optimal number of milled cycles, laser fluence, and scanning speed were 25, 4.9 J/cm2, and 200 mm/s, respectively. The width, height, and surface roughness of milled convex microchannels were 119.6±0.217 μm, 180.26±0.01 μm, and 0.672±0.08 μm, respectively. These measured values were close to the predicted values and suitable for a glass molding die. After the glass molding process, a typical glass-based microchannel chip was formed at a molding temperature of 660 °C and the molding force of 0.45 kN. The transcription rates of the microchannel width and depth were 100% and 99.6%, respectively. Thus, the proposed approach is suitable for performing in chemical, biochemical, or medical reactions.

Effect of simulated mechanical recycling processes on the structure and properties of poly(lactic acid).

PubMed

Beltrán, F R; Lorenzo, V; Acosta, J; de la Orden, M U; Martínez Urreaga, J

2018-06-15

The aim of this work is to study the effects of different simulated mechanical recycling processes on the structure and properties of PLA. A commercial grade of PLA was melt compounded and compression molded, then subjected to two different recycling processes. The first recycling process consisted of an accelerated ageing and a second melt processing step, while the other recycling process included an accelerated ageing, a demanding washing process and a second melt processing step. The intrinsic viscosity measurements indicate that both recycling processes produce a degradation in PLA, which is more pronounced in the sample subjected to the washing process. DSC results suggest an increase in the mobility of the polymer chains in the recycled materials; however the degree of crystallinity of PLA seems unchanged. The optical, mechanical and gas barrier properties of PLA do not seem to be largely affected by the degradation suffered during the different recycling processes. These results suggest that, despite the degradation of PLA, the impact of the different simulated mechanical recycling processes on the final properties is limited. Thus, the potential use of recycled PLA in packaging applications is not jeopardized. Copyright © 2017 Elsevier Ltd. All rights reserved.

High-rate production of micro- and nanostructured surfaces: Injection molding and novel process for metal tooling manufacturing

NASA Astrophysics Data System (ADS)

De Jesus Vega, Marisely

Devices containing micro and nanostructured surfaces are developing and constantly finding new applications, especially for medical diagnostics, point-of-care applications, and microneedles. They are also employed in the functionalization of surfaces for superhydrophobicity, drag reduction, or reversible adhesion by mimicking bio-inspired surfaces. This research provides a thorough investigation on the effects of different polymeric materials and processing conditions on the replication of micro and nanostructured surfaces via injection molding. In addition, this dissertation also presents a novel approach for the production of durable microstructured metal tooling to be used for the production of surfaces with microchannels via injection molding. Materials such as thermoplastic vulcanizates are substituting regular thermoplastic materials and vulcanized elastomers in many applications due to their outstanding properties and ease of processability. These material properties broaden the scope of applications for microstructured surfaces. However, there is a need for understanding how these materials behave in microinjection molding since thermoplastic elastomers' behavior during injection molding have been shown to differ from that of the widely understood behavior of thermoplastics. Replication of microstructured surfaces using thermoplastic vulcanizates (TPV) was studied in the first part of this thesis. TPVs with different hardness's were molded using microinjection molding with various processing conditions and the replication and surface details of 20 microm pillars (aspect ratio of 1:1) were characterized. In the second part of this research liquid silicone rubber (LSR) was studied as a material for the production of micro and nanostructured surfaces. LSR is a silicone based material such as polydimethylsiloxane (PDMS), which is widely used for research and development of micro and nanostructured devices, and thus provides all the benefits of PDMS but can be rapidly processed via liquid injection molding. LSR with its excellent mechanical properties, transparency, non-toxicity and rapid molding capabilities can bring the production of micro and nanostructured surfaces from laboratory research facilities to high-rate manufacturing. However, previous research on microstructured surfaces made off LSR does not focus on the processing aspect of this material. Therefore, there is a lack of understanding of how different processing conditions affect the replication of microstructures. Additionally, there are no reports molding nanostructures of LSR. Features between 115 microm and 0.250 microm were molded in this work and the effect of different processing conditions and features sizes were studied. For the last part of this work, a novel metal additive manufacturing technique was used for the production of microstructured surfaces to be used as tooling for injection molding. The printing method consists of metal pastes printed through a tip onto a steel substrate. Prior work has shown spreading and swelling of features when metal pastes extrude out of the printing tip. PDMS was studied as a binder material to minimize spreading and swelling of the features by curing right after printing. In addition, prior work has shown durability of this metal printed tool up to 5000 injection molding cycles. This work compares this durability to durability of commercially available selective laser sintering metal tools. Furthermore, surface roughness was studied as this is one of the most important things to consider when molding microchannels for certain applications.

Method for making an elastomeric member with end pieces

DOEpatents

Hoppie, L.O.; McNinch, J.H. Jr.; Nowell, G.C.

1984-10-23

A molding process is described for molding an elongated elastomeric member with wire mesh sleeves bonded to the ends. A molding preform of elastomeric material is positioned within a seamless mold cylinder, and the open ends of the wire mesh sleeves are mounted to end plug assemblies slidably received into the mold cylinder and positioned against the ends of the preform. A specialized profile is formed into surfaces of the respective end plug assemblies and by heating of the mold, the ends of the elastomeric preform are molded to the profile, as well as bonded to the reinforcing wire mesh sleeves. Vacuum is applied to the interior of the mold to draw outgassing vapors through relief spaces there through. The completed elastomeric member is removed from the mold cylinder by stretching, the consequent reduction in diameter enabling ready separation from the mold cylinder and removal thereof. 9 figs.

PMR polyimides from solutions containing mixed endcaps

NASA Technical Reports Server (NTRS)

Delvigs, P.

1985-01-01

Previous studies have shown that partial substitution of p-aminostyrene (PAS) for the monomethylester of endo-5-norbornene-2, 3-dicarboxylic acid (NE) lowered the cure temperature of PMR polyimides from 316 to 260 C, but the modified PMR polyimides required higher compression-molding pressures than state-of-the-art PMR-15. In this study PMR polyimides are prepared employing three encaps: NE, PAS, and endo-N-phenyl-5-norbornene-2,3-dicarboximide (PN). The effect of PN addition on the processing characteristics and glass transition temperatures of graphite fiber-reinforced PMR composites is studied. The room temperature and short-time 316 C mechanical properties of the composites are determined. The weight loss and mechanical property retention characteristics of the composites after exposure in air at 316 C are also determined.

An investigation into the injection molding of PMR-15 polyimide

NASA Technical Reports Server (NTRS)

Colaluca, M. A.

1984-01-01

The chemorheological behavior of the PRM-15 molding compounds were characterized, the range of suitable processing parameters for injection molding in a reciprocating screw injection molding machine was determined, and the effects of the injection molding processing parameters on the mechanical properties of molded PMR-15 parts were studied. The apparatus and procedures for measuring viscosity and for determining the physical response of the material during heating are described. Results show that capillary rheometry can be effectively used with thermosets if the equipment is designed to overcome some of the inherent problems of these materials. A uniform temperature was provided in the barrel by using a circulating hot oil system. Standard capillary rheometry methods can provide the dependence of thermoset apparent viscosity on shear rate, temperature, and time. Process conditions resulting in complete imidization should be carefully defined. Specification of controlled oven temperature is inadequate and can result in incomplete imidization. For completely imidized PMR-15 heat at 15 C/min melt flow without gas evolution occurs in the temperature range of 325 C to 400 C.

Factors that affect micro-tooling features created by direct printing approach

NASA Astrophysics Data System (ADS)

Kumbhani, Mayur N.

Current market required faster pace production of smaller, better, and improved products in shorter amount of time. Traditional high-rate manufacturing process such as hot embossing, injection molding, compression molding, etc. use tooling to replicate feature on a products. Miniaturization of many product in the field of biomedical, electronics, optical, and microfluidic is occurring on a daily bases. There is a constant need to produce cheaper, and faster tooling, which can be utilize by existing manufacturing processes. Traditionally, in order to manufacture micron size tooling features processes such as micro-machining, Electrical Discharge Machining (EDM), etc. are utilized. Due to a higher difficulty to produce smaller size features, and longer production cycle time, various additive manufacturing approaches are proposed, e.g. selective laser sintering (SLS), inkjet printing (3DP), fused deposition modeling (FDM), etc. were proposed. Most of these approaches can produce net shaped products from different materials such as metal, ceramic, or polymers. Several attempts were made to produce tooling features using additive manufacturing approaches. Most of these produced tooling were not cost effective, and the life cycle of these tooling was reported short. In this research, a method to produce tooling features using direct printing approach, where highly filled feedstock was dispensed on a substrate. This research evaluated different natural binders, such as guar gum, xanthan gum, and sodium carboxymethyl cellulose (NaCMC) and their combinations were evaluated. The best binder combination was then use to evaluate effect of different metal (316L stainless steel (3 mum), 316 stainless steel (45 mum), and 304 stainless steel (45 mum)) particle size on feature quality. Finally, the effect of direct printing process variables such as dispensing tip internal diameter (500 mum, and 333 mum) at different printing speeds were evaluated.

Intelligent methods for the process parameter determination of plastic injection molding

NASA Astrophysics Data System (ADS)

Gao, Huang; Zhang, Yun; Zhou, Xundao; Li, Dequn

2018-03-01

Injection molding is one of the most widely used material processing methods in producing plastic products with complex geometries and high precision. The determination of process parameters is important in obtaining qualified products and maintaining product quality. This article reviews the recent studies and developments of the intelligent methods applied in the process parameter determination of injection molding. These intelligent methods are classified into three categories: Case-based reasoning methods, expert system- based methods, and data fitting and optimization methods. A framework of process parameter determination is proposed after comprehensive discussions. Finally, the conclusions and future research topics are discussed.

40 CFR Table 1 to Subpart Wwww of... - Equations To Calculate Organic HAP Emissions Factors for Specific Open Molding and Centrifugal...

Code of Federal Regulations, 2010 CFR

2010-07-01

... Emissions Factors for Specific Open Molding and Centrifugal Casting Process Streams 1 Table 1 to Subpart... Standards for Hazardous Air Pollutants: Reinforced Plastic Composites Production Pt. 63, Subpt. WWWW, Table... Specific Open Molding and Centrifugal Casting Process Streams ER25AU05.020 ER25AU05.021 [70 FR 50129, Aug...

Method of casting pitch based foam

DOEpatents

Klett, James W.

2002-01-01

A process for producing molded pitch based foam is disclosed which minimizes cracking. The process includes forming a viscous pitch foam in a container, and then transferring the viscous pitch foam from the container into a mold. The viscous pitch foam in the mold is hardened to provide a carbon foam having a relatively uniform distribution of pore sizes and a highly aligned graphic structure in the struts.

Simple and cost-effective fabrication of solid biodegradable polymer microneedle arrays with adjustable aspect ratio for transdermal drug delivery using acupuncture microneedles

NASA Astrophysics Data System (ADS)

Cha, Kyoung Je; Kim, Taewan; Jea Park, Sung; Kim, Dong Sung

2014-11-01

Polymer microneedle arrays (MNAs) have received much attention for their use in transdermal drug delivery and microneedle therapy systems due to the advantages they offer, such as low cost, good mechanical properties, and a versatile choice of materials. Here, we present a simple and cost-effective method for the fabrication of a biodegradable polymer MNA in which the aspect ratio of each microneedle is adjustable using commercially available acupuncture microneedles. In our process, a master template with acupuncture microneedles, whose shape will be the final MNA, was carefully prepared by fixing them onto a plastic substrate with selectively drilled holes which, in turn, determine the aspect ratios of the microneedles. A polylactic acid (PLA; a biodegradable polymer) MNA was fabricated by a micromolding process with a polydimethylsiloxane (PDMS) mold containing the cavity of the microneedles, which was obtained by the PDMS replica molding against the master template. The mechanical force and degradation behavior of the replicated PLA MNA were characterized with the help of a compression test and an accelerated degradation test, respectively. Finally, the transdermal drug delivery performance of the PLA MNA was successfully simulated by two different methods of penetration and staining, using the skin of a pig cadaver. These results indicated that the proposed method can be effectively used for the fabrication of polymer MNAs which can be used in various microneedle applications.

Process for Forming a High Temperature Single Crystal Canted Spring

NASA Technical Reports Server (NTRS)

DeMange, Jeffrey J (Inventor); Ritzert, Frank J (Inventor); Nathal, Michael V (Inventor); Dunlap, Patrick H (Inventor); Steinetz, Bruce M (Inventor)

2017-01-01

A process for forming a high temperature single crystal canted spring is provided. In one embodiment, the process includes fabricating configurations of a rapid prototype spring to fabricate a sacrificial mold pattern to create a ceramic mold and casting a canted coiled spring to form at least one canted coil spring configuration based on the ceramic mold. The high temperature single crystal canted spring is formed from a nickel-based alloy containing rhenium using the at least one coil spring configuration.

Microstructure and Deformation Response of TRIP-Steel Syntactic Foams to Quasi-Static and Dynamic Compressive Loads

PubMed Central

Ehinger, David; Weise, Jörg; Baumeister, Joachim; Funk, Alexander; Krüger, Lutz; Martin, Ulrich

2018-01-01

The implementation of hollow S60HS glass microspheres and Fillite 106 cenospheres in a martensitically transformable AISI 304L stainless steel matrix was realized by means of metal injection molding of feedstock with varying fractions of the filler material. The so-called TRIP-steel syntactic foams were studied with respect to their behavior under quasi-static compression and dynamic impact loading. The interplay between matrix material behavior and foam structure was discussed in relation to the findings of micro-structural investigations, electron back scatter diffraction EBSD phase analyses and magnetic measurements. During processing, the cenospheres remained relatively stable retaining their shape while the glass microspheres underwent disintegration associated with the formation of pre-cracked irregular inclusions. Consequently, the AISI 304L/Fillite 106 syntactic foams exhibited a higher compression stress level and energy absorption capability as compared to the S60HS-containing variants. The α′ -martensite kinetic of the steel matrix was significantly influenced by material composition, strain rate and arising deformation temperature. The highest ferromagnetic α′-martensite phase fraction was detected for the AISI 304L/S60HS batches and the lowest for the TRIP-steel bulk material. Quasi-adiabatic sample heating, a gradual decrease in strain rate and an enhanced degree of damage controlled the mechanical deformation response of the studied syntactic foams under dynamic impact loading. PMID:29695107

Development of heat resistant geopolymer-based materials from red mud and rice husk ash

NASA Astrophysics Data System (ADS)

Thang, Nguyen Hoc; Nhung, Le Thuy; Quyen, Pham Vo Thi Ha; Phong, Dang Thanh; Khe, Dao Thanh; Van Phuc, Nguyen

2018-04-01

Geopolymer is an inorganic polymer composite developed by Joseph Davidovits in 1970s. Such material has potentials to replace Ordinary Portland Cement (OPC)-based materials in the future because of its lower energy consumption, minimal CO2 emissions and lower production cost as it utilizes industrial waste resources. Hence, geopolymerization and the process to produce geopolymers for various applications like building materials can be considered as green industry. Moreover, in this study, red mud and rice husk ash were used as raw materials for geopolymeric production, which are aluminum industrial and agricultural wastes that need to be managed to reduce their negative impact to the environment. The red mud and rice husk ash were mixed with sodium silicate (water glass) solution to form geopolymer paste. The geopolymer paste was filled into 5-cm cube molds according to ASTM C109/C109M 99, and then cured at room temperature for 28 days. These products were then tested for compressive strength and volumetric weight. Results indicated that the material can be considered lightweight with a compressive strength at 28 days that are in the range of 6.8 to 15.5 MPa. Moreover, the geopolymer specimens were also tested for heat resistance at a temperature of 1000oC for 2 hours. Results suggest high heat resistance with an increase of compressive strength from 262% to 417% after exposed at high temperature.

Microstructure and Deformation Response of TRIP-Steel Syntactic Foams to Quasi-Static and Dynamic Compressive Loads.

PubMed

Ehinger, David; Weise, Jörg; Baumeister, Joachim; Funk, Alexander; Waske, Anja; Krüger, Lutz; Martin, Ulrich

2018-04-24

The implementation of hollow S60HS glass microspheres and Fillite 106 cenospheres in a martensitically transformable AISI 304L stainless steel matrix was realized by means of metal injection molding of feedstock with varying fractions of the filler material. The so-called TRIP-steel syntactic foams were studied with respect to their behavior under quasi-static compression and dynamic impact loading. The interplay between matrix material behavior and foam structure was discussed in relation to the findings of micro-structural investigations, electron back scatter diffraction EBSD phase analyses and magnetic measurements. During processing, the cenospheres remained relatively stable retaining their shape while the glass microspheres underwent disintegration associated with the formation of pre-cracked irregular inclusions. Consequently, the AISI 304L/Fillite 106 syntactic foams exhibited a higher compression stress level and energy absorption capability as compared to the S60HS-containing variants. The α ′ -martensite kinetic of the steel matrix was significantly influenced by material composition, strain rate and arising deformation temperature. The highest ferromagnetic α ′ -martensite phase fraction was detected for the AISI 304L/S60HS batches and the lowest for the TRIP-steel bulk material. Quasi-adiabatic sample heating, a gradual decrease in strain rate and an enhanced degree of damage controlled the mechanical deformation response of the studied syntactic foams under dynamic impact loading.

Organic materials for ceramic molding processes

NASA Technical Reports Server (NTRS)

Saito, K.

1984-01-01

Ceramic molding processes are examined. Binders, wetting agents, lubricants, plasticizers, surface active agents, dispersants, etc., for pressing, rubber pressing, sip casting, injection casting, taping, extrusion, etc., are described, together with forming machines.

Investigation of Materials Processing Technology

DTIC Science & Technology

1993-07-01

Figure 6: Time-temperature curves of A357 casting in Cu mold ................. 12 Figure 7: Time-temperature curves of 17 -4 casting in ceramic mold...simulation of 17 -4 ................ 17 Figure 12: IHTC from IHEAT simulation of 17 -4 casting ..................... 18 Figure 13: Temperature profiles...mold used for Ti castings .......................... 23 Figure 16: Cooling curves for a Ti casting in ceramic mold .................. 24 Figure 17

Precision injection molding of freeform optics

NASA Astrophysics Data System (ADS)

Fang, Fengzhou; Zhang, Nan; Zhang, Xiaodong

2016-08-01

Precision injection molding is the most efficient mass production technology for manufacturing plastic optics. Applications of plastic optics in field of imaging, illumination, and concentration demonstrate a variety of complex surface forms, developing from conventional plano and spherical surfaces to aspheric and freeform surfaces. It requires high optical quality with high form accuracy and lower residual stresses, which challenges both optical tool inserts machining and precision injection molding process. The present paper reviews recent progress in mold tool machining and precision injection molding, with more emphasis on precision injection molding. The challenges and future development trend are also discussed.

High-strength mineralized collagen artificial bone

NASA Astrophysics Data System (ADS)

Qiu, Zhi-Ye; Tao, Chun-Sheng; Cui, Helen; Wang, Chang-Ming; Cui, Fu-Zhai

2014-03-01

Mineralized collagen (MC) is a biomimetic material that mimics natural bone matrix in terms of both chemical composition and microstructure. The biomimetic MC possesses good biocompatibility and osteogenic activity, and is capable of guiding bone regeneration as being used for bone defect repair. However, mechanical strength of existing MC artificial bone is too low to provide effective support at human load-bearing sites, so it can only be used for the repair at non-load-bearing sites, such as bone defect filling, bone graft augmentation, and so on. In the present study, a high strength MC artificial bone material was developed by using collagen as the template for the biomimetic mineralization of the calcium phosphate, and then followed by a cold compression molding process with a certain pressure. The appearance and density of the dense MC were similar to those of natural cortical bone, and the phase composition was in conformity with that of animal's cortical bone demonstrated by XRD. Mechanical properties were tested and results showed that the compressive strength was comparable to human cortical bone, while the compressive modulus was as low as human cancellous bone. Such high strength was able to provide effective mechanical support for bone defect repair at human load-bearing sites, and the low compressive modulus can help avoid stress shielding in the application of bone regeneration. Both in vitro cell experiments and in vivo implantation assay demonstrated good biocompatibility of the material, and in vivo stability evaluation indicated that this high-strength MC artificial bone could provide long-term effective mechanical support at human load-bearing sites.

Synthesis of an Al-Mn-Based Alloy Containing In Situ-Formed Quasicrystals and Evaluation of Its Mechanical and Corrosion Properties

NASA Astrophysics Data System (ADS)

Naglič, Iztok; Samardžija, Zoran; Delijić, Kemal; Kobe, Spomenka; Leskovar, Blaž; Markoli, Boštjan

2018-05-01

An Al-Mn alloy with additions of copper, magnesium, and silicon was prepared and cast into a copper mold. It contains in situ-formed icosahedral quasicrystals (iQCs), as confirmed by electron backscatter diffraction. The aim of this work is to present the mechanical and corrosion properties of this alloy and compare its properties with some conventional commercial materials. The compressive strength and compressive yield strength were 751 MPa and 377 MPa, while the compressive fracture strain was 19%. It was observed that intensive shearing caused the final fracture of the specimens and the fractured iQC dendrites still showed cohesion with the α-Al matrix. The polarization resistance and corrosion rate of the artificially aged alloy were 7.30 kΩ and 1.2 μm/year. The evaluated properties are comparable to conventional, discontinuously reinforced aluminum metal-matrix composites and structural wrought aluminum alloys.

A new class of sonic composites

NASA Astrophysics Data System (ADS)

Munteanu, Ligia; Chiroiu, Veturia; Donescu, Ştefania; Brişan, Cornel

2014-03-01

Transformation acoustics opens a new avenue towards the architecture, modeling and simulation of a new class of sonic composites with scatterers made of various materials and having various shapes embedded in an epoxy matrix. The design of acoustic scatterers is based on the property of Helmholtz equations to be invariant under a coordinate transformation, i.e., a specific spatial compression is equivalent to a new material in a new space. In this paper, the noise suppression for a wide full band-gap of frequencies is discussed for spherical shell scatterers made of auxetic materials (materials with negative Poisson's ratio). The original domain consists of spheres made from conventional foams with positive Poisson's ratio. The spatial compression is controlled by the coordinate transformation, and leads to an equivalent domain filled with an auxetic material. The coordinate transformation is strongly supported by the manufacturing of auxetics which is based on the pore size reduction through radial compression molds.

Test and Analyses of a Composite Multi-Bay Fuselage Panel Under Uni-Axial Compression

NASA Technical Reports Server (NTRS)

Li, Jian; Baker, Donald J.

2004-01-01

A composite panel containing three stringers and two frames cut from a vacuum-assisted resin transfer molded (VaRTM) stitched fuselage article was tested under uni-axial compression loading. The stringers and frames divided the panel into six bays with two columns of three bays each along the compressive loading direction. The two frames were supported at the ends with pins to restrict the out-of-plane translation. The free edges of the panel were constrained by knife-edges. The panel was modeled with shell finite elements and analyzed with ABAQUS nonlinear solver. The nonlinear predictions were compared with the test results in out-of-plane displacements, back-to-back surface strains on stringer flanges and back-to-back surface strains at the centers of the skin-bays. The analysis predictions were in good agreement with the test data up to post-buckling.

Development of Metal Plate with Internal Structure Utilizing the Metal Injection Molding (MIM) Process.

PubMed

Shin, Kwangho; Heo, Youngmoo; Park, Hyungpil; Chang, Sungho; Rhee, Byungohk

2013-12-12

In this study, we focus on making a double-sided metal plate with an internal structure, such as honeycomb. The stainless steel powder was used in the metal injection molding (MIM) process. The preliminary studies were carried out for the measurement of the viscosity of the stainless steel feedstock and for the prediction of the filling behavior through Computer Aided Engineering (CAE) simulation. PE (high density polyethylene (HDPE) and low density polyethylene (LDPE)) and polypropylene (PP) resins were used to make the sacrificed insert with a honeycomb structure using a plastic injection molding process. Additionally, these sacrificed insert parts were inserted in the metal injection mold, and the metal injection molding process was carried out to build a green part with rectangular shape. Subsequently, debinding and sintering processes were adopted to remove the sacrificed polymer insert. The insert had a suitable rigidity that was able to endure the filling pressure. The core shift analysis was conducted to predict the deformation of the insert part. The 17-4PH feedstock with a low melting temperature was applied. The glass transition temperature of the sacrificed polymer insert would be of a high grade, and this insert should be maintained during the MIM process. Through these processes, a square metal plate with a honeycomb structure was made.

Development of Metal Plate with Internal Structure Utilizing the Metal Injection Molding (MIM) Process

PubMed Central

Shin, Kwangho; Heo, Youngmoo; Park, Hyungpil; Chang, Sungho; Rhee, Byungohk

2013-01-01

In this study, we focus on making a double-sided metal plate with an internal structure, such as honeycomb. The stainless steel powder was used in the metal injection molding (MIM) process. The preliminary studies were carried out for the measurement of the viscosity of the stainless steel feedstock and for the prediction of the filling behavior through Computer Aided Engineering (CAE) simulation. PE (high density polyethylene (HDPE) and low density polyethylene (LDPE)) and polypropylene (PP) resins were used to make the sacrificed insert with a honeycomb structure using a plastic injection molding process. Additionally, these sacrificed insert parts were inserted in the metal injection mold, and the metal injection molding process was carried out to build a green part with rectangular shape. Subsequently, debinding and sintering processes were adopted to remove the sacrificed polymer insert. The insert had a suitable rigidity that was able to endure the filling pressure. The core shift analysis was conducted to predict the deformation of the insert part. The 17-4PH feedstock with a low melting temperature was applied. The glass transition temperature of the sacrificed polymer insert would be of a high grade, and this insert should be maintained during the MIM process. Through these processes, a square metal plate with a honeycomb structure was made. PMID:28788427

Surface quality of unsaturated polyester resin processed via continuous multi-shot rotational molding

NASA Astrophysics Data System (ADS)

Ogila, K. O.; Yang, W.; Shao, M.; Tan, J.

2017-05-01

Unsaturated Polyester Resin is a versatile and cost efficient thermosetting plastic whose application in rotational molding is currently limited by its relatively high initial viscosity and heat of reaction. These material characteristics result in uneven material distribution, poor surface finish and imperfections in the moldings especially when large wall thicknesses are required. The current work attempts to remedy these shortcomings through the development of a continuous multi-shot system which adds predetermined loads of unsaturated polyester resin into a rotating mold at various intervals. As part of this system, a laboratory-scale uniaxial rotational molding machine was used to produce Unsaturated Polyester Resin moldings in single and double shots. Optimal processing conditions were determined through visual studies, three dimensional microscopic studies, thickness distribution analysis and Fourier Transform Infrared spectroscopy. Volume filling fractions of 0.049-0.065, second shot volumes of 0.5-0.75 from the first shot, rotational speeds of 15-20 rpm and temperatures of 30-50 °C resulted in moldings of suitable quality on both the inner and outer surfaces.

Enabling Learning through the Assessment Process

DTIC Science & Technology

2010-04-08

Software, 47. 32 a specific pattern over time.”98 Johnson provides an example of this when discussing the computer simulation of slime mold growth. He...asserts that since the designers understood the underlying interactions between the individual slime molds , they could increase or decrease the...density of individual mold cells and the aggregating chemical that is required for the molds to group together. Furthermore, Johnson suggests that this

Photopolymerizable liquid encapsulants for microelectronic devices

NASA Astrophysics Data System (ADS)

Baikerikar, Kiran K.

2000-10-01

Plastic encapsulated microelectronic devices consist of a silicon chip that is physically attached to a leadframe, electrically interconnected to input-output leads, and molded in a plastic that is in direct contact with the chip, leadframe, and interconnects. The plastic is often referred to as the molding compound, and is used to protect the chip from adverse mechanical, thermal, chemical, and electrical environments. Encapsulation of microelectronic devices is typically accomplished using a transfer molding process in which the molding compound is cured by heat. Most transfer molding processes suffer from significant problems arising from the high operating temperatures and pressures required to fill the mold. These aspects of the current process can lead to thermal stresses, incomplete mold filling, and wire sweep. In this research, a new strategy for encapsulating microelectronic devices using photopolymerizable liquid encapsulants (PLEs) has been investigated. The PLEs consist of an epoxy novolac-based vinyl ester resin (˜25 wt.%), fused silica filler (70--74 wt.%), and a photoinitiator, thermal initiator, and silane coupling agent. For these encapsulants, the use of light, rather than heat, to initiate the polymerization allows precise control over when the reaction starts, and therefore completely decouples the mold filling and the cure. The low viscosity of the PLEs allows for low operating pressures and minimizes problems associated with wire sweep. In addition, the in-mold cure time for the PLEs is equivalent to the in-mold cure times of current transfer molding compounds. In this thesis, the thermal and mechanical properties, as well as the viscosity and adhesion of photopolymerizable liquid encapsulants, are reported in order to demonstrate that a UV-curable formulation can have the material properties necessary for microelectronic encapsulation. In addition, the effects of the illumination time, postcure time, fused silica loading, and the inclusion of a thermal initiator on the thermal and mechanical properties of the final cured encapsulants have been investigated. The results show that the material properties of the PLEs are the same, if not better, than those exhibited by conventional transfer molding compounds and demonstrate the potential of using PLEs for encapsulating microelectronic devices.

Phenylethynyl Containing Polyarylene Ethers/Polyimides Resin Infiltration of Composites

NASA Technical Reports Server (NTRS)

Dunn, DeRome O.

1998-01-01

The following tasks were performed at NCA&TSU during the second year in performance of the grant. LaRC-LV-1 13 resin was synthesized at NCA&TSU. In order to perform the synthesis, glassware and needed apparatus were purchased with grant funds along with the appropriate monomers. It was found that the LaRC-LV-1 13 resin was easily synthesized by the NMP solvent/toluene imminization/distilled water precipitation process. However, in use this resin exhibited a bubbling/foaming behavior during cure that was detrimental leading to the production of composite panels having a high void content. Composite panels were fabricated using compression molding and resin transfer molding (RTM) techniques. Initial fiber volume determinations were computed at NCA&TSU along with NASA-Langley measured c-scans on the panels produced. The initial results indicated a unsatisfactory level of approximately 20% by volume of voids. Testing of uniaxial coupons in compression to failure also agreed with these results. The uniaxial coupons delaminated as the major mode of failure indicative of an unacceptably low level of resin and to much void content in the final composites produced. In discussions with Dr. Brian Jensen, it was suggested the void fraction needs to be reduced to at least 2% by volume for a useful composite. The panels produced used both resin synthesized at NASA-Langley and NCA&TSU. In reviewing our progress over the past year, it was noted that the resin as formulated by the current synthesis process bubbled at elevated temperature. This was especially observed in neat resin slugs cured at the recommended one, four and eight hour cure temperatures. Pressurized cures where then performed with pressures up to 200 psi and simultaneously the lowest eight hour cure temperatures. Although this procedure reduced the amount of bubbles to some extent in the neat resin slugs it did not completely eliminate them. The cure reaction appears to be very energetic even at the lowest recommended cure temperature. Currently, the pressurized cure apparatus developed at NCA&TSU is limited to 200 psi.

Method for making an elastomeric member with end pieces

DOEpatents

Hoppie, Lyle O.; McNinch, Jr., Joseph H.; Nowell, Gregory C.

1984-01-01

A molding process for molding an elongated elastomeric member (60) with wire mesh sleeves (16) bonded to the ends (14). A molding preform (10) of elastomeric material is positioned within a seamless mold cylinder (26), and the open ends of the wire mesh sleeves (16) are mounted to end plug assemblies (30) slidably received into the mold cylinder (26) and positioned against the ends (14) of the preform (10). A specialized profile is formed into surfaces (44) of the respective end plug assemblies (30) and by heating of the mold (26), the ends (14) of the elastomeric preform (10) are molded to the profile, as well as bonded to the reinforcing wire mesh sleeves (16). Vacuum is applied to the interior of the mold to draw outgassing vapors through relief spaces therethrough. The completed elastomeric member (60) is removed from the mold cylinder (26) by stretching, the consequent reduction in diameter enabling ready separation from the mold cylinder (26) and removal thereof.

Transferability of glass lens molding

NASA Astrophysics Data System (ADS)

Katsuki, Masahide

2006-02-01

Sphere lenses have been used for long time. But it is well known that sphere lenses theoretically have spherical aberration, coma and so on. And, aspheric lenses attract attention recently. Plastic lenses are molded easily with injection machines, and are relatively low cost. They are suitable for mass production. On the other hand, glass lenses have several excellent features such as high refractive index, heat resistance and so on. Many aspheric glass lenses came to be used for the latest digital camera and mobile phone camera module. It is very difficult to produce aspheric glass lenses by conventional process of curve generating and polishing. For the solution of this problem, Glass Molding Machine was developed and is spreading through the market. High precision mold is necessary to mold glass lenses with Glass Molding Machine. The mold core is ground or turned by high precision NC aspheric generator. To obtain higher transferability of the mold core, the function of the molding machine and the conditions of molding are very important. But because of high molding temperature, there are factors of thermal expansion and contraction of the mold and glass material. And it is hard to avoid the factors. In this session, I introduce following items. [1] Technology of glass molding and the machine is introduced. [2] The transferability of glass molding is analyzed with some data of glass lenses molded. [3] Compensation of molding shape error is discussed with examples.

Additive technology of soluble mold tooling for embedded devices in composite structures: A study on manufactured tolerances

NASA Astrophysics Data System (ADS)

Roy, Madhuparna

Composite textiles have found widespread use and advantages in various industries and applications. The constant demand for high quality products and services requires companies to minimize their manufacturing costs, and delivery time in order to compete in general and niche marketplaces. Advanced manufacturing methods aim to provide economical methods of mold production. Creation of molding and tooling options for advanced composites encompasses a large portion of the fabrication time, making it a costly process and restraining factor. This research discusses a preliminary investigation into the use of soluble polymer compounds and additive manufacturing to fabricate soluble molds. These molds suffer from dimensional errors due to several factors, which have also been characterized. The basic soluble mold of a composite is 3D printed to meet the desired dimensions and geometry of holistic structures or spliced components. The time taken to dissolve the mold depends on the rate of agitation of the solvent. This process is steered towards enabling the implantation of optoelectronic devices within the composite to provide sensing capability for structural health monitoring. The shape deviation of the 3D printed mold is also studied and compared to its original dimensions to optimize the dimensional quality to produce dimensionally accurate parts. Mechanical tests were performed on compact tension (CT) resin samples prepared from these 3D printed molds and revealed crack propagation towards an embedded intact optical fiber.

Injection molding ceramics to high green densities

NASA Technical Reports Server (NTRS)

Mangels, J. A.; Williams, R. M.

1983-01-01

The injection molding behavior of a concentrated suspension of Si powder in wax was studied. It was found that the injection molding behavior was a function of the processing techniques used to generate the powder. Dry ball-milled powders had the best molding behavior, while air classified and impact-milled powders demonstrated poorer injection moldability. The relative viscosity of these molding batches was studied as a function of powder properties: distribution shape, surface area, packing density, and particle morphology. The experimental behavior, in all cases, followed existing theories. The relative viscosity of an injection molding composition composed of dry ball-milled powders could be expressed using Farris' relation.

Pressurized Shell Molds For Metal-Matrix Composites

NASA Technical Reports Server (NTRS)

Kashalikar, Uday K.; Lusignea, Richard N.; Cornie, James

1993-01-01

Balanced-pressure molds used to make parts in complex shapes from fiber-reinforced metal-matrix composite materials. In single step, molding process makes parts in nearly final shapes; only minor finishing needed. Because molding pressure same on inside and outside, mold does not have to be especially strong and can be made of cheap, nonstructural material like glass or graphite. Fibers do not have to be cut to conform to molds. Method produces parts with high content of continuous fibers. Parts stiff but light in weight, and coefficients of thermal expansion adjusted. Parts resistant to mechanical and thermal fatigue superior to similar parts made by prior fabrication methods.

Rotationally Molded Liquid Crystalline Polymers

NASA Technical Reports Server (NTRS)

Rogers, Martin; Scribben, Eric; Baird, Donald; Hulcher, Bruce

2002-01-01

Rotational molding is a unique process for producing hollow plastic parts. Rotational molding offers low cost tooling and can produce very large parts with complicated shapes. Products made by rotational molding include water tanks with capacities up to 20,000 gallons, truck bed liners, playground equipment, air ducts, Nylon fuel tanks, pipes, toys, stretchers, kayaks, pallets, and many others. Thermotropic liquid crystalline polymers are an important class of engineering resins employed in a wide variety of applications. Thermotropic liquid crystalline polymers resins are composed of semirigid, nearly linear polymeric chains resulting in an ordered mesomorphic phase between the crystalline solid and the isotropic liquid. Ordering of the rigid rod-like polymers in the melt phase yields microfibrous, self-reinforcing polymer structures with outstanding mechanical and thermal properties. Rotational molding of liquid crystalline polymer resins results in high strength and high temperature hollow structures useful in a variety of applications. Various fillers and reinforcements can potentially be added to improve properties of the hollow structures. This paper focuses on the process and properties of rotationally molded liquid crystalline polymers. This paper will also highlight the interactions between academia and small businesses in developing new products and processes.

Micro Dot Patterning on the Light Guide Panel Using Powder Blasting

PubMed Central

Jang, Ho Su; Cho, Myeong Woo; Park, Dong Sam

2008-01-01

This study is to develop a micromachining technology for a light guide panel(LGP) mold, whereby micro dot patterns are formed on a LGP surface by a single injection process instead of existing screen printing processes. The micro powder blasting technique is applied to form micro dot patterns on the LGP mold surface. The optimal conditions for masking, laminating, exposure, and developing processes to form the micro dot patterns are first experimentally investigated. A LGP mold with masked micro patterns is then machined using the micro powder blasting method and the machinability of the micro dot patterns is verified. A prototype LGP is test- injected using the developed LGP mold and a shape analysis of the patterns and performance testing of the injected LGP are carried out. As an additional approach, matte finishing, a special surface treatment method, is applied to the mold surface to improve the light diffusion characteristics, uniformity and brightness of the LGP. The results of this study show that the applied powder blasting method can be successfully used to manufacture LGPs with micro patterns by just single injection using the developed mold and thereby replace existing screen printing methods. PMID:27879740

Surface quality and microstructure of low-vacuum sintered orthodontic bracket 17-4 PH stainless steel fabricated by MIM process

NASA Astrophysics Data System (ADS)

Suharno, Bambang; Suharno, Lingga Pradinda; Saputro, Hantoro Restucondro; Irawan, Bambang; Prasetyadi, Tjokro; Ferdian, Deni; Supriyadi, Sugeng

2018-02-01

Surface roughness and microstructure play important role on orthodontic bracket quality. Therefore, orthodontic brackets need to have smooth surface roughness to reduce the friction and bacterial adhesion. Microstructure of orthodontic brackets also determine the mechanical properties and corrosion resistance. There are two methods to produce orthodontic bracket, investment casting and metal injection molding. The purpose of this study is to observe the surface roughness and microstructure of orthodontic bracket which were made from two different fabrication methods. To produce orthodontic bracket with metal injection molding method, 17-4 PH stainless steel feedstock was injected to the orthodontic bracket mold using injection molding machine. After injection, the binder was eliminated with solvent and thermal debinding. Solvent debinding process was conducted with hexane at 50 °C on magnetic stirrer for 1.5 hours. Thermal debinding process was conducted at 510 °C with 0.5 °C/min heat rate and 120 min holding time. Hereafter, sintering process were performed with vacuum tube furnace at 1360 °C with heat rate 5 °C/min and 90 min holding time in low vacuum atmosphere. To produce orthodontic bracket with investment casting method, the wax was injected into the mold then the wax pattern was arranged into the tree form. The tree form was then dipped into ceramic slurry and allowed to harden, the ceramic slurry has a thickness in the region of 10 mm. The ceramic mold was then heated at a temperature of over than 1100°C to strengthen the ceramic mold and to remove the remaining wax. After that, the molten 17-4 PH stainless steel was poured into the ceramic mold at a temperature of over 1600°C. The natural cooling process was carried out at temperature of 25°C, after which the ceramic mold was broken away. Then, the orthodontic bracket was cut from the tree form. The results show that the orthodontic bracket which were made with investment casting fabrication method have low porosity, high density, and there is no indication of secondary phase on the microstructure. However, it has rough brackets surface. Whereas, the production of orthodontic brackets using metal injection molding method resulted in better surface roughness. But, it has relatively high porosity, presence of another phase on the microstructure, and low density.

Cyclic tests of P-bulb end-seal designs for a shuttle-type wing-elevon cove membrane seal

NASA Technical Reports Server (NTRS)

Hunt, L. R.

1979-01-01

Four P-bulb end seal designs were tested at room temperature in a cyclic seal test apparatus. Test results show that all the P-bulb end seals have the durability required for a 100 mission life (neglecting possible elevated-temperature effects) and three of the four P-bulbs provide an adequate seal against a 7.0-kPa air pressure differential. Antifriction material attached to the P-bulb rub surface reduced friction slightly but could degrade the sealing effectiveness. A flat rub surface molded into the P-bulb discouraged wrinkling and rolling and thereby reduced leakage. However, the P-bulbs lacked resilience, as indicated by increased leakage when P-bulb compression was reduced. The best P-bulb design tested included an antifriction interface bonded to a flat surface molded into the P-bulb.

Soft lithography of ceramic microparts using wettability-tunable poly(dimethylsiloxane) (PDMS) molds

NASA Astrophysics Data System (ADS)

Su, Bo; Zhang, Aijun; Meng, Junhu; Zhang, Zhaozhu

2016-07-01

Green alumina microparts were fabricated from a high solid content aqueous suspension by microtransfer molding using air plasma-treated poly(dimethylsiloxane) (PDMS) molds. The wettability of the air plasma-treated PDMS molds spontaneously changed between the hydrophilic and hydrophobic states during the process. Initial hydrophilicity of the air plasma-treated PDMS molds significantly improved the flowability of the concentrated suspension. Subsequent hydrophobic recovery of the air plasma-treated PDMS molds enabled a perfect demolding of the green microparts. Consequently, defect-free microchannel parts of 60 μm and a micromixer with an area of several square centimeters were successfully fabricated. In soft lithography, tuning the wetting behavior of PDMS molds has a great effect on the quality of ceramic microparts. Using wettability-tunable PDMS molds has great potential in producing complex-shaped and large-area ceramic microparts and micropatterns.

Estimation of state and material properties during heat-curing molding of composite materials using data assimilation: A numerical study.

PubMed

Matsuzaki, Ryosuke; Tachikawa, Takeshi; Ishizuka, Junya

2018-03-01

Accurate simulations of carbon fiber-reinforced plastic (CFRP) molding are vital for the development of high-quality products. However, such simulations are challenging and previous attempts to improve the accuracy of simulations by incorporating the data acquired from mold monitoring have not been completely successful. Therefore, in the present study, we developed a method to accurately predict various CFRP thermoset molding characteristics based on data assimilation, a process that combines theoretical and experimental values. The degree of cure as well as temperature and thermal conductivity distributions during the molding process were estimated using both temperature data and numerical simulations. An initial numerical experiment demonstrated that the internal mold state could be determined solely from the surface temperature values. A subsequent numerical experiment to validate this method showed that estimations based on surface temperatures were highly accurate in the case of degree of cure and internal temperature, although predictions of thermal conductivity were more difficult.

Simulation of cracking cores when molding piston components

NASA Astrophysics Data System (ADS)

Petrenko, Alena; Soukup, Josef

2014-08-01

The article deals with pistons casting made from aluminum alloy. Pistons are casting at steel mold with steel core. The casting is provided by gravity casting machine. The each machine is equipped by two metal molds, which are preheated above temperature 160 °C before use. The steel core is also preheated by flame. The metal molds and cores are heated up within the casting process. The temperature of the metal mold raise up to 200 °C and temperature of core is higher. The surface of the core is treated by nitration. The mold and core are cooled down by water during casting process. The core is overheated and its top part is finally cracked despite its intensive water-cooling. The life time cycle of the core is decreased to approximately 5 to 15 thousands casting, which is only 15 % of life time cycle of core for production of other pistons. The article presents the temperature analysis of the core.

Turbine blade processing

NASA Technical Reports Server (NTRS)

1975-01-01

Space processing of directionally solidified eutectic-alloy type turbine blades is envisioned as a simple remelt operations in which precast blades are remelted in a preformed mold. Process systems based on induction melting, continuous resistance furnaces, and batch resistance furnaces were evaluated. The batch resistance furnace type process using a multiblade mold is considered to offer the best possibility for turbine blade processing.

A thermoplastic polyimidesulfone. [synthesis of processable and solvent resistant system

NASA Technical Reports Server (NTRS)

St. Clair, T. L.; Yamaki, D. A.

1984-01-01

A polymer system has been prepared which has the excellent thermoplastic properties generally associated with polysulfones, and the solvent resistance and thermal stability of aromatic polyimides. This material, with improved processability over the base polyimide, can be processed in the 260-325 C range in such a manner as to yield high quality, tough unfilled moldings; strong, high-temperature-resistant adhesive bonds; and well consolidated, graphite-fiber-reinforced moldings (composites). The unfilled moldings have physical properties that are similar to aromatic polysulfones which demonstrates the potential as an engineering thermoplastic. The adhesive bonds exhibit excellent retention of initial strength levels even after thermal aging for 5000 hours at 232 C. The graphite-fiber-reinforced moldings have mechanical properties which makes this polymer attractive for the fabrication of structural composites.

Fabrication and characterization of nanoclay modified PMR type polyimide composites reinforced with 3D woven basalt fabric

NASA Astrophysics Data System (ADS)

Xie, Jianfei; Qiu, Yiping

2009-07-01

Nanoclay modified PMR type polyimide composites were prepared from 3D orthogonal woven basalt fiber performs and nanoclay modified polyimide matrix resin, which derived from methylene dianiline (MDA), dimethyl ester of 3,3',4,4'- oxydiphthalic acid (ODPE), monomethyl ester of cis-5-norbornene-endo-2,3-dicarboxylic acid (NE) and nanoclay. The Na+-montmorillonite was organically treated using a 1:1 molar ratio mixture of dodecylamine (C12) and MDA. The rheological properties of neat B-stage PMR polyimide and 2% clay modified B-stage PMR polyimide were investigated. Based on the results obtained from the rheological tests, a two step compression molding process can be established for the composites. In the first step, the 3D fabric preforms were impregnated with polyimide resin in a vacuum oven and heated up for degassing the volatiles and by-products. In the second step, composites were compressed. The internal structure of the composites was observed by a microscope. Incorporation of 2% clay showed an improvement in the Tg and stiffness of the PMR polyimide. The resulting composites exhibited high thermal stability and good mechanical properties.

Local deformation behavior of surface porous polyether-ether-ketone.

PubMed

Evans, Nathan T; Torstrick, F Brennan; Safranski, David L; Guldberg, Robert E; Gall, Ken

2017-01-01

Surface porous polyether-ether-ketone has the ability to maintain the tensile monotonic and cyclic strength necessary for many load bearing orthopedic applications while providing a surface that facilitates bone ingrowth; however, the relevant deformation behavior of the pore architecture in response to various loading conditions is not yet fully characterized or understood. The focus of this study was to examine the compressive and wear behavior of the surface porous architecture using micro Computed Tomography (micro CT). Pore architectures of various depths (~0.5-2.5mm) and pore sizes (212-508µm) were manufactured using a melt extrusion and porogen leaching process. Compression testing revealed that the pore architecture deforms in the typical three staged linear elastic, plastic, and densification stages characteristic of porous materials. The experimental moduli and yield strengths decreased as the porosity increased but there was no difference in properties between pore sizes. The porous architecture maintained a high degree of porosity available for bone-ingrowth at all strains. Surface porous samples showed no increase in wear rate compared to injection molded samples, with slight pore densification accompanying wear. Copyright © 2016 Elsevier Ltd. All rights reserved.

Experimental Tests on the Composite Foam Sandwich Pipes Subjected to Axial Load

NASA Astrophysics Data System (ADS)

Li, Feng; Zhao, QiLin; Xu, Kang; Zhang, DongDong

2015-12-01

Compared to the composite thin-walled tube, the composite foam sandwich pipe has better local flexural rigidity, which can take full advantage of the high strength of composite materials. In this paper, a series of composite foam sandwich pipes with different parameters were designed and manufactured using the prefabricated polyurethane foam core-skin co-curing molding technique with E-glass fabric prepreg. The corresponding axial-load compressive tests were conducted to investigate the influence factors that experimentally determine the axial compressive performances of the tubes. In the tests, the detailed failure process and the corresponding load-displacement characteristics were obtained; the influence rules of the foam core density, surface layer thickness, fiber ply combination and end restraint on the failure modes and ultimate bearing capacity were studied. Results indicated that: (1) the fiber ply combination, surface layer thickness and end restraint have a great influence on the ultimate load bearing capacity; (2) a reasonable fiber ply combination and reliable interfacial adhesion not only optimize the strength but also transform the failure mode from brittle failure to ductile failure, which is vital to the fully utilization of the composite strength of these composite foam sandwich pipes.

Investigation of Heat Transfer at the Mold/Metal Interface in Permanent Mold Casting of Light Alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Robert D. Pehlke; John T. Berry

2005-12-16

Accurate modeling of the metal casting process prior to creating a mold design demands reliable knowledge of the interfacial heat transfer coefficient at the mold metal interface as a function of both time and location. The phenomena concerned with the gap forming between the mold and the solidifying metal are complex but need to be understood before any modeling is attempted. The presence of mold coatings further complicates the situation. A commercial casting was chosen and studied in a gravity permanent mold casting process. The metal/mold interfacial heat transfer coefficient (IHTC) was the focus of the research. A simple, directmore » method has been used to evaluate the IHTC. Both the simulation and experiments have shown that a reasonably good estimate of the heat transfer coefficient could be made in the case studied. It has been found that there is a good agreement between experiments and simulations in the temperature profiles during the solidification process, given that the primary mechanism of heat transfer across the gap in permanent mold casting of light alloys is by conduction across the gap. The procedure utilized to determine the interfacial heat transfer coefficient can be applied to other casting processes. A recently completed project involving The University of Michigan and Mississippi State University, together with several industrial partners, which was supported by the USDOE through the Cast Metals Coalition, examined a number of cases of thermal contact. In an investigation which gave special consideration to the techniques of measurement, several mold coatings were employed and results presented as a function of time. Realistic conditions of coating thickness and type together with an appropriate combination of mold preheat and metal pouring temperature were strictly maintained throughout the investigation. Temperature sensors, in particular thermocouples, play an important part in validating the predictions of solidification models. Cooling curve information, as well as temperature gradient history both in the solidifying metal and within the mold are invariably required to be validated. This validation depends upon the response of the sensor concerned, but also on its own effect upon the thermal environment. A joint university/industry team has completed an investigation of the invasive effects of thermocouples upon temperature history in permanent molds determining the degree of uncertainty associated with placement and indicating how the time-temperature history may be recovered. In addition to its relevance to the all important study of thermal contact of the casting with metallic molds, the observations also impact the determination of heat flux and interfacial heat transfer coefficients. In these respects the study represents the first of its kind that has tackled the problem in depth for permanent mold castings. An important ramification of this investigation has been the errors likely to be encountered in mold temperature measurement with thin section aluminum castings, especially with respect to the plans for thermocouple placement. A comparison between the degree of uncertainty experienced in sand molds compared with that found in permanent molds reveals that the associated problems have a lesser impact. These conclusions and the related recommendations have been disseminated to industry and the technical community through project reports and publications.« less

Multiphysics modeling of the steel continuous casting process

NASA Astrophysics Data System (ADS)

Hibbeler, Lance C.

This work develops a macroscale, multiphysics model of the continuous casting of steel. The complete model accounts for the turbulent flow and nonuniform distribution of superheat in the molten steel, the elastic-viscoplastic thermal shrinkage of the solidifying shell, the heat transfer through the shell-mold interface with variable gap size, and the thermal distortion of the mold. These models are coupled together with carefully constructed boundary conditions with the aid of reduced-order models into a single tool to investigate behavior in the mold region, for practical applications such as predicting ideal tapers for a beam-blank mold. The thermal and mechanical behaviors of the mold are explored as part of the overall modeling effort, for funnel molds and for beam-blank molds. These models include high geometric detail and reveal temperature variations on the mold-shell interface that may be responsible for cracks in the shell. Specifically, the funnel mold has a column of mold bolts in the middle of the inside-curve region of the funnel that disturbs the uniformity of the hot face temperatures, which combined with the bending effect of the mold on the shell, can lead to longitudinal facial cracks. The shoulder region of the beam-blank mold shows a local hot spot that can be reduced with additional cooling in this region. The distorted shape of the funnel mold narrow face is validated with recent inclinometer measurements from an operating caster. The calculated hot face temperatures and distorted shapes of the mold are transferred into the multiphysics model of the solidifying shell. The boundary conditions for the first iteration of the multiphysics model come from reduced-order models of the process; one such model is derived in this work for mold heat transfer. The reduced-order model relies on the physics of the solution to the one-dimensional heat-conduction equation to maintain the relationships between inputs and outputs of the model. The geometric parameters in the model are calibrated such that the reduced-order model temperatures match a small, periodic subdomain of the mold. These parameters are demonstrated to be insensitive to the calibration conditions. The thermal behavior of the detailed, three-dimensional mold models used in this work can be approximated closely with a few arithmetic calculations after calibrating the reduced-order model of mold heat transfer. The example application of the model includes the effects of the molten steel jet on the solidification front and the ferrostatic pressure. The model is demonstrated to match measurements of mold heat removal and the thickness of a breakout shell all the way around the perimeter of the mold, and gives insight to the cause of breakouts in a beam-blank caster. This multiphysics modeling approach redefines the state of the art of process modeling for continuous casting, and can be~used in future work to explore the formation and prevention of defects and other practical issues. This work also explores the eigen-problem for an arbitrary 3x3 matrix. An explicit, algebraic formula for the eigenvectors is presented.

Molding of strength testing samples using modern PDCPD material for purpose of automotive industry

NASA Astrophysics Data System (ADS)

Grabowski, L.; Baier, A.; Sobek, M.

2017-08-01

The casting of metal materials is widely known but the molding of composite polymer materials is not well-known method still. The initial choice of method for producing composite bodies was the method of casting of PDCPD material. For purpose of performing casting of polymer composite material, a special mold was made. Firstly, the 3D printed, using PLA material, mold was used. After several attempts of casting PDCPD many problems were encountered. The second step was to use mold milled from a firm and dense isocyanate foam. After several attempts research shown that this solution is more resistant to high-temperature peak, but this material is too fragile to use it several times. This solution also prevents mold from using external heating, which can be necessary for performing correct molding process. The last process was to use the aluminum mold, which is dedicated to PDCPD polymer composite, because of low adhesiveness. This solution leads to perform correct PDCPD polymer composite material injection. After performing casting operation every PDCPD testing samples were tested. These results were compared together. The result of performed work was to archive correct properties of injection of composite material. Research and results were described in detail in this paper.

40 CFR 463.21 - Specialized definitions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... AND STANDARDS (CONTINUED) PLASTICS MOLDING AND FORMING POINT SOURCE CATEGORY Cleaning Water... “average process water usage flow rate” for a plant with more than one plastics molding and forming process... a cleaning process and comes in contact with the plastic product over a period of one year. ...

40 CFR 463.31 - Specialized definitions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... AND STANDARDS (CONTINUED) PLASTICS MOLDING AND FORMING POINT SOURCE CATEGORY Finishing Water... “average process water usage flow rate” for a plant with more than one plastics molding and forming process... a finishing water process and comes in contact with the plastics product over a period of one year. ...

40 CFR 463.21 - Specialized definitions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... AND STANDARDS (CONTINUED) PLASTICS MOLDING AND FORMING POINT SOURCE CATEGORY Cleaning Water... “average process water usage flow rate” for a plant with more than one plastics molding and forming process... a cleaning process and comes in contact with the plastic product over a period of one year. ...

40 CFR 463.31 - Specialized definitions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... AND STANDARDS (CONTINUED) PLASTICS MOLDING AND FORMING POINT SOURCE CATEGORY Finishing Water... “average process water usage flow rate” for a plant with more than one plastics molding and forming process... a finishing water process and comes in contact with the plastics product over a period of one year. ...

Preliminary guidelines and recommendations for the development of material and process specifications for carbon fiber-reinforced liquid resin molded materials.

DOT National Transportation Integrated Search

2007-05-01

This document recommends guidance and criteria for the development of material and process specifications and material acceptance documents for liquid resins and continuous carbon fiber reinforcement materials used in liquid molding processes to manu...

The study about forming high-precision optical lens minimalized sinuous error structures for designed surface

NASA Astrophysics Data System (ADS)

Katahira, Yu; Fukuta, Masahiko; Katsuki, Masahide; Momochi, Takeshi; Yamamoto, Yoshihiro

2016-09-01

Recently, it has been required to improve qualities of aspherical lenses mounted on camera units. Optical lenses in highvolume production generally are applied with molding process using cemented carbide or Ni-P coated steel, which can be selected from lens material such as glass and plastic. Additionally it can be obtained high quality of the cut or ground surface on mold due to developments of different mold product technologies. As results, it can be less than 100nmPV as form-error and 1nmRa as surface roughness in molds. Furthermore it comes to need higher quality, not only formerror( PV) and surface roughness(Ra) but also other surface characteristics. For instance, it can be caused distorted shapes at imaging by middle spatial frequency undulations on the lens surface. In this study, we made focus on several types of sinuous structures, which can be classified into form errors for designed surface and deteriorate optical system performances. And it was obtained mold product processes minimalizing undulations on the surface. In the report, it was mentioned about the analyzing process by using PSD so as to evaluate micro undulations on the machined surface quantitatively. In addition, it was mentioned that the grinding process with circumferential velocity control was effective for large aperture lenses fabrication and could minimalize undulations appeared on outer area of the machined surface, and mentioned about the optical glass lens molding process by using the high precision press machine.

An Investigation of the Mold-Flux Performance for the Casting of Cr12MoV Steel Using a Mold Simulator Technique

NASA Astrophysics Data System (ADS)

Zhou, Lejun; Wang, Wanlin; Xu, Chao; Zhang, Chen

2017-08-01

Mold flux plays important roles in the process of continuous casting. In this article, the performance of mold flux for the casting of Cr12MoV steel was investigated by using a mold simulator. The results showed that the slag film formed in the gap between the initial shell and mold hot surface is thin and discontinuous during the casting process with the Flux BM, due to the absorption of chromic oxide inclusions into the liquid slag, while the slag film formed in the case of the optimized Flux NEW casting process is uniform. The main precipitated crystals in Flux BM slag film are cuspidine (Ca4Si2O7F2) and Cr3O4, but only Ca4Si2O7F2 precipitated in the Flux NEW case. Besides, both the responding temperature and heat flux in the case of Flux BM are relatively higher and fluctuate in a larger amplitude. The surface of the shell obtained in the case of the Flux BM experiment is quite uneven, and many severe depressions, cracks, and entrapped slags are observed in the surface due to the lack of lubrication. However, the obtained shell surface in the case of the Flux NEW shows good surface quality due to the addition of B2O3 and the adjustment of basicity, which can compensate for the negative effects of the mold-flux properties caused by the absorption of chromic oxide during the casting process.

Fabrication of a high aspect ratio thick silicon wafer mold and electroplating using flipchip bonding for MEMS applications

NASA Astrophysics Data System (ADS)

Kim, Bong-Hwan; Kim, Jong-Bok

2009-06-01

We have developed a microfabrication process for high aspect ratio thick silicon wafer molds and electroplating using flipchip bonding with THB 151N negative photoresist (JSR micro). This fabrication technique includes large area and high thickness silicon wafer mold electroplating. The process consists of silicon deep reactive ion etching (RIE) of the silicon wafer mold, photoresist bonding between the silicon mold and the substrate, nickel electroplating and a silicon removal process. High thickness silicon wafer molds were made by deep RIE and flipchip bonding. In addition, nickel electroplating was developed. Dry film resist (ORDYL MP112, TOK) and thick negative-tone photoresist (THB 151N, JSR micro) were used as bonding materials. In order to measure the bonding strength, the surface energy was calculated using a blade test. The surface energy of the bonding wafers was found to be 0.36-25.49 J m-2 at 60-180 °C for the dry film resist and 0.4-1.9 J m-2 for THB 151N in the same temperature range. Even though ORDYL MP112 has a better value of surface energy than THB 151N, it has a critical disadvantage when it comes to removing residue after electroplating. The proposed process can be applied to high aspect ratio MEMS structures, such as air gap inductors or vertical MEMS probe tips.

RTM: Cost-effective processing of composite structures

NASA Technical Reports Server (NTRS)

Hasko, Greg; Dexter, H. Benson

1991-01-01

Resin transfer molding (RTM) is a promising method for cost effective fabrication of high strength, low weight composite structures from textile preforms. In this process, dry fibers are placed in a mold, resin is introduced either by vacuum infusion or pressure, and the part is cured. RTM has been used in many industries, including automotive, recreation, and aerospace. Each of the industries has different requirements of material strength, weight, reliability, environmental resistance, cost, and production rate. These requirements drive the selection of fibers and resins, fiber volume fractions, fiber orientations, mold design, and processing equipment. Research is made into applying RTM to primary aircraft structures which require high strength and stiffness at low density. The material requirements are discussed of various industries, along with methods of orienting and distributing fibers, mold configurations, and processing parameters. Processing and material parameters such as resin viscosity, perform compaction and permeability, and tool design concepts are discussed. Experimental methods to measure preform compaction and permeability are presented.

Gravity Effects in Small-Scale Structural Modeling

DTIC Science & Technology

1988-12-01

attenuating material (Reference 23). The materials tested were cellular concrete with fly ash, expanded polystyrene concrete with fly ash, foamed...polyurethane, foamed sulfer and molded expanded polystyrene . The studies showed that with proper adjustments in the cement content, water-cement ratio and foam...Compression (Ou,c) 4000 100 Tension (Ou,t) 400 10 E/Quc 1000 1000 Ou,c/Ou,t 10 10 Further analysis of the properties of expanded polystyrene concrete with

Cross-stiffened continuous fiber structures

NASA Technical Reports Server (NTRS)

Ewen, John R.; Suarez, Jim A.

1993-01-01

Under NASA's Novel Composites for Wing and Fuselage Applications (NCWFA) program, Contract NAS1-18784, Grumman is evaluating the structural efficiency of graphite/epoxy cross-stiffened panel elements fabricated using innovative textile preforms and cost effective Resin Transfer Molding (RTM) and Resin Film Infusion (RFI) processes. Two three-dimensional woven preform assembly concepts have been defined for application to a representative window belt design typically found in a commercial transport airframe. The 3D woven architecture for each of these concepts is different; one is vertically woven in the plane of the window belt geometry and the other is loom woven in a compressed state similar to an unfolded eggcrate. The feasibility of both designs has been demonstrated in the fabrication of small test element assemblies. These elements and the final window belt assemblies will be structurally tested, and results compared.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kassen, Aaron G.; White, Emma M. H.; Tang, Wei

We present economic uncertainty in the rare earth (RE) permanent magnet marketplace, as well as in an expanding electric drive vehicle market that favors permanent magnet alternating current synchronous drive motors, motivated renewed research in RE-free permanent magnets like “alnico,” an Al-Ni-Co-Fe alloy. Thus, high-pressure, gas-atomized isotropic type-8H pre-alloyed alnico powder was compression molded with a clean burn-out binder to near-final shape and sintered to density >99% of cast alnico 8 (full density of 7.3 g/cm 3). To produce aligned sintered alnico magnets for improved energy product and magnetic remanence, uniaxial stress was attempted to promote controlled grain growth, avoidingmore » directional solidification that provides alignment in alnico 9. Lastly, successful development of solid-state powder processing may enable anisotropically aligned alnico magnets with enhanced energy density to be mass-produced.« less

Porogen-based solid freeform fabrication of polycaprolactone-calcium phosphate scaffolds for tissue engineering.

PubMed

Mondrinos, Mark J; Dembzynski, Robert; Lu, Lin; Byrapogu, Venkata K C; Wootton, David M; Lelkes, Peter I; Zhou, Jack

2006-09-01

Drop on demand printing (DDP) is a solid freeform fabrication (SFF) technique capable of generating microscale physical features required for tissue engineering scaffolds. Here, we report results toward the development of a reproducible manufacturing process for tissue engineering scaffolds based on injectable porogens fabricated by DDP. Thermoplastic porogens were designed using Pro/Engineer and fabricated with a commercially available DDP machine. Scaffolds composed of either pure polycaprolactone (PCL) or homogeneous composites of PCL and calcium phosphate (CaP, 10% or 20% w/w) were subsequently fabricated by injection molding of molten polymer-ceramic composites, followed by porogen dissolution with ethanol. Scaffold pore sizes, as small as 200 microm, were attainable using the indirect (porogen-based) method. Scaffold structure and porosity were analyzed by scanning electron microscopy (SEM) and microcomputed tomography, respectively. We characterized the compressive strength of 90:10 and 80:20 PCL-CaP composite materials (19.5+/-1.4 and 24.8+/-1.3 Mpa, respectively) according to ASTM standards, as well as pure PCL scaffolds (2.77+/-0.26 MPa) fabricated using our process. Human embryonic palatal mesenchymal (HEPM) cells attached and proliferated on all scaffolds, as evidenced by fluorescent nuclear staining with Hoechst 33258 and the Alamar Blue assay, with increased proliferation observed on 80:20 PCL-CaP scaffolds. SEM revealed multilayer assembly of HEPM cells on 80:20 PCL-CaP composite, but not pure PCL, scaffolds. In summary, we have developed an SFF-based injection molding process for the fabrication of PCL and PCL-CaP scaffolds that display in vitro cytocompatibility and suitable mechanical properties for hard tissue repair.

Processing and Characterization of Functionally Graded Aluminum (A319)—SiCp Metallic Composites by Centrifugal Casting Technique

NASA Astrophysics Data System (ADS)

Jayakumar, E.; Jacob, Jibin C.; Rajan, T. P. D.; Joseph, M. A.; Pai, B. C.

2016-08-01

Functionally graded materials (FGM) are successfully adopted for the design and fabrication of engineering components with location-specific properties. The present study describes the processing and characterization of A319 Aluminum functionally graded metal matrix composites (FGMMC) with 10 and 15 wt pct SiCp reinforcements. The liquid stir casting method is used for composite melt preparation followed by FGMMC formation by vertical centrifugal casting method. The process parameters used are the mold preheating temperature of 523 K (250 °C), melt pouring temperature of 1013 K (740 °C), and mold rotation speed of 1300 rpm. The study analyzes the distribution and concentration of reinforcement particles in the radial direction of the FGMMC disk along with the effects of gradation on density, hardness, mechanical strength, the variation in coefficient of thermal expansion and the wear resistance properties at different zones. Microstructures of FGMMC reveal an outward radial gradient distribution of reinforcements forming different zones. Namely, matrix-rich inner, transition, particles-rich outer, and chill zone of a few millimeters thick at the outer most periphery of the casting are formed. From 10-FGM, a radial shift in the position of SiCp maxima is observed in 15-FGM casting. The mechanical characterization depicts enhanced properties for the particle-rich zone. The hardness shows a graded nature in correlation with particle concentration and a maximum of 94.4 HRB has been obtained at the particle-rich region of 15-FGM. In the particle-rich zone, the lowest CTE value of 20.1 µm/mK is also observed with a compressive strength of 650 MPa and an ultimate tensile strength of 279 MPa. The wear resistance is higher at the particle-rich zone of the FGMMC.

Characterization of curing behavior of UV-curable LSR for LED embedded injection mold

NASA Astrophysics Data System (ADS)

Tae, Joon-Sung; Yim, Kyung-Gyu; Rhee, Byung-Ohk; Kwak, Jae B.

2016-11-01

For many applications, liquid silicone rubber (LSR) injection molding is widely used for their great design flexibility and high productivity. In particular, a sealing part for a mobile device such as smartphone and watch has been produced by injection molding. While thermally curable LSR causes deformation problem due to a high mold temperature, UV-curable LSR can be molded at room temperature, which has advantages for over-molding with inserts of temperature-sensitive materials. Ultraviolet light-emitting diodes (UV LEDs) have advantages such as a longer service life, a lower heat dissipation, and smaller size to equip into the mold than conventional halogen or mercury UV lamps. In this work, rheological behavior of UV-curable LSR during curing process was analyzed by UV LEDs available in the market. UV-LEDs of various wave lengths and intensities were tested. The steady shear test was applied to find the starting time of curing and the SAOS was applied to find the ending time of curing to estimate processing time. In addition, the hardness change with irradiation energy was compared with the rheological data to confirm the reliability of the rheological test.

Neodymium: YAG laser damage threshold. A comparison of injection-molded and lathe-cut polymethylmethacrylate intraocular lenses.

PubMed

Wilson, S E; Brubaker, R F

1987-01-01

The possibility that injection-molded intraocular lenses (IOLs) with imperfections called iridescent clefts could have a decreased threshold to neodymium: YAG (Nd:YAG) laser-induced damage was investigated. Thresholds for Nd:YAG laser-induced damage were determined for injection-molded and lathe-cut polymethylmethacrylate lenses. When aimed at a membrane in contact with a posterior convex surface, the average thresholds were 0.96 +/- 0.18 mJ (Standard deviation [SD]) and 1.80 +/- 0.55 mJ, respectively. The difference was significant at P = 0.001. When injection-molding polymethylmethacrylate was used to make lathe-cut IOLs, very few iridescent clefts were present, and the threshold to Nd:YAG laser-induced damage was 0.94 +/- 0.25 mJ. Iridescent clefts are therefore produced during the injection-molding process but they do not lower the threshold to Nd:YAG laser-induced damage. Rather, the reduced threshold in injection-molded lenses is most probably a result of the polymethylmethacrylate used in their manufacture. Clinically, iridescent clefts in a lens suggest that it has been manufactured by an injection-molding process and that Nd:YAG laser posterior capsulotomy must be performed at the lowest possible energy level to avoid damage.

Method of Fabricating Chopped-Fiber Composite Piston

NASA Technical Reports Server (NTRS)

Rivers, H. Kevin (Inventor); Ransone, Philip O. (Inventor); Northam, G. Burton (Inventor)

1999-01-01

A three-dimensional piston molding is fabricated from a mixture of chopped, carbon tow filaments of variable length, which are prepregged with carbonaceous organic resins and/or pitches and molded by conventional molding processes into a near net shape, to form a carbon-fiber reinforced organic-matrix composite part. Continuous reinforcement in the form of carbon-carbon composite tapes or pieces of fabric can be also laid in the mold before or during the charging of the mold with the chopped-fiber mixture, to enhance the strength in the crown and wrist-pin areas. The molded chopped-fiber reinforced organic-matrix composite parts are then pyrolized in an inert atmosphere, to convert the organic matrix materials to carbon. These pyrolized parts are then densified by reimpregnation with resins or pitches, which are subsequently carbonized. Densification is also accomplished by direct infiltration with carbon by vapor deposition processes. Once the desired density has been achieved, the piston molds are machined to final piston dimensions, and piston ring grooves are added. To prevent oxidation and/or to seal the piston surface or near surface, the chopped-fiber piston is coated with ceramic and/or metallic sealants: and/or coated with a catalyst.

Process of modifying a cable end

DOEpatents

Roose, L.D.

1995-08-01

End moldings for high-voltage cables are described wherein the dielectric insulator of the cable is heated and molded to conform to a desired shape. As a consequence, high quality substantially bubble-free cable connectors suitable for mating to premanufactured fittings are made. Disclosed are a method for making the cable connectors either in the field or in a factory, molds suitable for use with the method, and the molded cable connectors, themselves. 5 figs.

Fabrication of injection molded sintered alpha SiC turbine components

NASA Technical Reports Server (NTRS)

Storm, R. S.; Ohnsorg, R. W.; Frechette, F. J.

1981-01-01

Fabrication of a sintered alpha silicon carbide turbine blade by injection molding is described. An extensive process variation matrix was carried out to define the optimum fabrication conditions. Variation of molding parameters had a significant impact on yield. Turbine blades were produced in a reasonable yield which met a rigid quality and dimensional specification. Application of injection molding technology to more complex components such as integral rotors is also described.

Making High-Tensile-Strength Amalgam Components

NASA Technical Reports Server (NTRS)

Grugel, Richard

2008-01-01

Structural components made of amalgams can be made to have tensile strengths much greater than previously known to be possible. Amalgams, perhaps best known for their use in dental fillings, have several useful attributes, including room-temperature fabrication, corrosion resistance, dimensional stability, and high compressive strength. However, the range of applications of amalgams has been limited by their very small tensile strengths. Now, it has been discovered that the tensile strength of an amalgam depends critically on the sizes and shapes of the particles from which it is made and, consequently, the tensile strength can be greatly increased through suitable choice of the particles. Heretofore, the powder particles used to make amalgams have been, variously, in the form of micron-sized spheroids or flakes. The tensile reinforcement contributed by the spheroids and flakes is minimal because fracture paths simply go around these particles. However, if spheroids or flakes are replaced by strands having greater lengths, then tensile reinforcement can be increased significantly. The feasibility of this concept was shown in an experiment in which electrical copper wires, serving as demonstration substitutes for copper powder particles, were triturated with gallium by use of a mortar and pestle and the resulting amalgam was compressed into a mold. The tensile strength of the amalgam specimen was then measured and found to be greater than 10(exp 4) psi (greater than about 69 MPa). Much remains to be done to optimize the properties of amalgams for various applications through suitable choice of starting constituents and modification of the trituration and molding processes. The choice of wire size and composition are expected to be especially important. Perusal of phase diagrams of metal mixtures could give insight that would enable choices of solid and liquid metal constituents. Finally, whereas heretofore, only binary alloys have been considered for amalgams, ternary additions to liquid or solid components should be considered as means to impart desired properties to amalgams.

Effect of Additives on Green Sand Molding Properties using Design of Experiments and Taguchi's Quality Loss Function - An Experimental Study

NASA Astrophysics Data System (ADS)

Desai, Bhagyashree; Mokashi, Pavani; Anand, R. L.; Burli, S. B.; Khandal, S. V.

2016-09-01

The experimental study aims to underseek the effect of various additives on the green sand molding properties as a particular combination of additives could yield desired sand properties. The input parameters (factors) selected were water and powder (Fly ash, Coconut shell and Tamarind) in three levels. Experiments were planned using design of experiments (DOE). On the basis of plans, experiments were conducted to understand the behavior of sand mould properties such as compression strength, shear strength, permeability number with various additives. From the experimental results it could be concluded that the factors have significant effect on the sand properties as P-value found to be less than 0.05 for all the cases studied. The optimization based on quality loss function was also performed. The study revealed that the quality loss associated with the tamarind powder was lesser compared to other additives selected for the study. The optimization based on quality loss function and the parametric analysis using ANOVA suggested that the tamarind powder of 8 gm per Kg of molding sand and moisture content of 7% yield better properties to obtain sound castings.

Design and thermal analysis of a mold used in the injection of elastomers

NASA Astrophysics Data System (ADS)

Fekiri, Nasser; Canto, Cécile; Madec, Yannick; Mousseau, Pierre; Plot, Christophe; Sarda, Alain

2017-10-01

In the process of injection molding of elastomers, improving the energy efficiency of the tools is a current challenge for industry in terms of energy consumption, productivity and product quality. In the rubber industry, 20% of the energy consumed by capital goods comes from heating processes; more than 50% of heat losses are linked to insufficient control and thermal insulation of Molds. The design of the tooling evolves in particular towards the reduction of the heated mass and the thermal insulation of the molds. In this paper, we present a complex tool composed, on one hand, of a multi-cavity mold designed by reducing the heated mass and equipped with independent control zones placed closest to each molding cavity and, on the other hand, of a regulated channel block (RCB) which makes it possible to limit the waste of rubber during the injection. The originality of this tool lies in thermally isolating the regulated channel block from the mold and the cavities between them in order to better control the temperature field in the material which is transformed. We present the design and the instrumentation of the experimental set-up. Experimental measurements allow us to understand the thermal of the tool and to show the thermal heterogeneities on the surface of the mold and in the various cavities. Tests of injection molding of the rubber and a thermal balance on the energy consumption of the tool are carried out.

Processing research and development of 'green' polymer nanoclay composites containing a polyhydroxybutyrate, vinyl acetates, and modified montmorillonite clay

NASA Astrophysics Data System (ADS)

McKirahan, James N., Jr.

The purpose of this research was to determine the feasibility of direct melt-blending (intercalation) montmorillonite nanoclay to polyhydroxybutyrate along with vinyl acetate, at different weight percentages, to enhance plasticization using typical plastic processing equipment and typical processing methodology. The purpose was to determine and compare the specific mechanical properties of tensile strength and flexural strength developed as a result from this processing. Single screw and twin screw extrusion, Banbury mixer compounding, and compression molding were used to intercalate montmorillonite, and for sample preparation purposes, to test tensile and flexural strength of the resultant polymer clay nanocomposites (PCN). Results indicate Polyhydroxybutyrate and Ethylene vinyl acetate, and weight percentages of 70%, 65% and 60% PHB, and 15%, 20%, and 25% of EVA, respectively, influenced mechanical properties. The resultant materials remained in a mostly amorphous state. The nanoclay, at specific weight percentage of 10%, acted as an antimicrobial and preservative for the materials produced during the research. The intention of the research was to promote knowledge and understanding concerning these materials and processes so technology transfer regarding the use, mechanical properties, manufacture, and process ability of these bio-friendly materials to academia, industry, and society can occur.

Resin Flow Behavior Simulation of Grooved Foam Sandwich Composites with the Vacuum Assisted Resin Infusion (VARI) Molding Process

PubMed Central

Zhao, Chenhui; Zhang, Guangcheng; Wu, Yibo

2012-01-01

The resin flow behavior in the vacuum assisted resin infusion molding process (VARI) of foam sandwich composites was studied by both visualization flow experiments and computer simulation. Both experimental and simulation results show that: the distribution medium (DM) leads to a shorter molding filling time in grooved foam sandwich composites via the VARI process, and the mold filling time is linearly reduced with the increase of the ratio of DM/Preform. Patterns of the resin sources have a significant influence on the resin filling time. The filling time of center source is shorter than that of edge pattern. Point pattern results in longer filling time than of linear source. Short edge/center patterns need a longer time to fill the mould compared with Long edge/center sources.

Developing quartz wafer mold manufacturing process for patterned media

NASA Astrophysics Data System (ADS)

Chiba, Tsuyoshi; Fukuda, Masaharu; Ishikawa, Mikio; Itoh, Kimio; Kurihara, Masaaki; Hoga, Morihisa

2009-04-01

Recently, patterned media have gained attention as a possible candidate for use in the next generation of hard disk drives (HDD). Feature sizes on media are predicted to be 20-25 nm half pitch (hp) for discrete-track media in 2010. One method of fabricating such a fine pattern is by using a nanoimprint. The imprint mold for the patterned media is created from a 150-millimeter, rounded, quartz wafer. The purpose of the process introduced here was to construct a quartz wafer mold and to fabricate line and space (LS) patterns at 24 nmhp for DTM. Additionally, we attempted to achieve a dense hole (HOLE) pattern at 12.5 nmhp for BPM for use in 2012. The manufacturing process of molds for patterned media is almost the same as that for semiconductors, with the exception of the dry-etching process. A 150-millimeter quartz wafer was etched on a special tray made from carving a 6025 substrate, by using the photo-mask tool. We also optimized the quartz etching conditions. As a result, 24 nmhp LS and HOLE patterns were manufactured on the quartz wafer. In conclusion, the quartz wafer mold manufacturing process was established. It is suggested that the etching condition should be further optimized to achieve a higher resolution of HOLE patterns.

Warpage of QFN Package in Post Mold Cure Process of integrated circuit packaging

NASA Astrophysics Data System (ADS)

Sriwithoon, Nattha; Ugsornrat, Kessararat; Srisuwitthanon, Warayoot; Thonglor, Panakamon

2017-09-01

This research studied about warpage of QFN package in post mold cure process of integrated circuit (IC) packages using pre-plated (PPF) leadframe. For IC package, epoxy molding compound (EMC) are molded by cross linking of compound stiffness but incomplete crosslinked network and leading the fully cured thermoset by post mold cure (PMC) process. The cure temperature of PMC can change microstructure of EMC in term of stress inside the package and effect to warpage of the package due to coefficient of thermal expansion (CTE) between EMC and leadframe. In experiment, cure temperatures were varied to check the effect of internal stress due to different cure temperature after completed post mold cure for TDFN 2×3 8L. The cure temperature were varied with 180 °C, 170 °C, 160 °C, and 150°C with cure time 4 and 6 hours, respectively. For analysis, the TDFN 2×3 8L packages were analyzed the warpage by thickness gauge and scanning acoustic microscope (SAM) after take the test samples out from the oven cure. The results confirmed that effect of different CTE between EMC and leadframe due to different cure temperature resulting to warpage of the TDFN 2×3 8L packages.

Micro Machining of Injection Mold Inserts for Fluidic Channel of Polymeric Biochips

PubMed Central

Jung, Woo-Chul; Heo, Young-Moo; Yoon, Gil-Sang; Shin, Kwang-Ho; Chang, Sung-Ho; Kim, Gun-Hee; Cho, Myeong-Woo

2007-01-01

Recently, the polymeric micro-fluidic biochip, often called LOC (lab-on-a-chip), has been focused as a cheap, rapid and simplified method to replace the existing biochemical laboratory works. It becomes possible to form miniaturized lab functionalities on a chip with the development of MEMS technologies. The micro-fluidic chips contain many micro-channels for the flow of sample and reagents, mixing, and detection tasks. Typical substrate materials for the chip are glass and polymers. Typical techniques for microfluidic chip fabrication are utilizing various micro pattern forming methods, such as wet-etching, micro-contact printing, and hot-embossing, micro injection molding, LIGA, and micro powder blasting processes, etc. In this study, to establish the basis of the micro pattern fabrication and mass production of polymeric micro-fluidic chips using injection molding process, micro machining method was applied to form micro-channels on the LOC molds. In the research, a series of machining experiments using micro end-mills were performed to determine optimum machining conditions to improve surface roughness and shape accuracy of designed simplified micro-channels. Obtained conditions were used to machine required mold inserts for micro-channels using micro end-mills. Test injection processes using machined molds and COC polymer were performed, and then the results were investigated.

Development and Demonstration of Adanced Tooling Alloys for Molds and Dies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kevin M. McHugh; Enrique J. Lavernia

2006-01-01

This report summarizes research results in the project Development and Demonstration of Advanced Tooling Alloys for Molds and Dies. Molds, dies and related tooling are used to manufacture most of the plastic and metal products we use every day. Conventional fabrication of molds and dies involves a multiplicity of machining, benching and heat treatment unit operations. This approach is very expensive and time consuming. Rapid Solidifcation Process (RSP) Tooling is a spray-forming technology tailored for producing molds and dies. The appraoch combines rapid solidifcation processing and net-shape materials processing in a single step. An atomized spray of a tool-forming alloy,more » typically a tool steel, is deposited onto an easy-to-form tool pattern to replicate the pattern's shape and surface features. By so doing, the approach eliminates many machining operations in conventional mold making, significantly reducing cost, lead time and energy. Moreover, rapid solidification creates unique microstructural features by suppressing carbide precipitation and growth, and creating metastable phases. This can result in unique material properties following heat treatment. Spray-formed and aged tool steel dies have exhibited extended life compared to conventional dies in many forming operations such as forging, extrusion and die casting. RSP Tooling technolocy was commercialized with the formation of RSP Tooling, LLC in Solon, Oh.« less

Development of a continuous roll-to-roll processing system for mass production of plastic optical film

NASA Astrophysics Data System (ADS)

Chang, Chih-Yuan; Tsai, Meng-Hsun

2015-12-01

This paper reports a highly effective method for the mass production of large-area plastic optical films with a microlens array pattern based on a continuous roll-to-roll film extrusion and roller embossing process. In this study, a thin steel mold with a micro-circular hole array pattern is fabricated by photolithography and a wet chemical etching process. The thin steel mold was then wrapped onto a metal cylinder to form an embossing roller mold. During the roll-to-roll process operation, a thermoplastic raw material (polycarbonate grains) was put into the barrel of the plastic extruder with a flat T-die. Then, the molten polymer film was extruded and immediately pressed against the surface of the embossing roller mold. Under the proper processing conditions, the molten polymer will just partially fill the micro-circular holes of the mold and due to surface tension form a convex lens surface. A continuous plastic optical film with a microlens array pattern was obtained. Experiments are carried out to investigate the effect of plastic microlens formation on the roll-to-roll process. Finally, the geometrical and optical properties of the fabricated plastic optical film were measured and proved satisfactory. This technique shows great potential for the mass production of large-area plastic optical films with a microlens array pattern.

Microfluidic systems with embedded materials and structures and method thereof

DOEpatents

Morse, Jeffrey D [Martinez, CA; Rose, Klint A [Boston, MA; Maghribi, Mariam [Livermore, CA; Benett, William [Livermore, CA; Krulevitch, Peter [Pleasanton, CA; Hamilton, Julie [Tracy, CA; Graff, Robert T [Modesto, CA; Jankowski, Alan [Livermore, CA

2007-03-06

Described herein is a process for fabricating microfluidic systems with embedded components in which micron-scale features are molded into the polymeric material polydimethylsiloxane (PDMS). Micromachining is used to create a mold master and the liquid precursors for PDMS are poured over the mold and allowed to cure. The PDMS is then removed form the mold and bonded to another material such as PDMS, glass, or silicon after a simple surface preparation step to form sealed microchannels.

Development and manufacture of visor for helmet-mounted display

NASA Astrophysics Data System (ADS)

Krevor, David H.; McNelly, Gregg; Skubon, John; Speirs, Robert

2004-01-01

The manufacturing design and process development for the Visor for the JHMCS (Joint Helmet Mounted Cueing System) are discussed. The JHMCS system is a Helmet Mounted Display (HMD) system currently flying on the F-15, F-16 and F/A-18 aircraft. The Visor manufacturing processes are essential to both system performance and economy. The Visor functions both as the system optical combiner and personal protective equipment for the pilot. The Visor material is optical polycarbonate. For a military HMD system, the mechanical and environmental properties of the Visor are as necessary as the optical properties. The visor must meet stringent dimensional requirements to assure adequate system optical performance. Injection molding can provide dimensional fidelity to the requirements, if done properly. Concurrent design of the visor and the tool (i.e., the injection mold) is essential. The concurrent design necessarily considers manufacturing operations and the use environment of the Visor. Computer modeling of the molding process is a necessary input to the mold design. With proper attention to product design and tool development, it is possible to improve upon published standard dimensional tolerances for molded polycarbonate articles.

Progress in Titanium Metal Powder Injection Molding.

PubMed

German, Randall M

2013-08-20

Metal powder injection molding is a shaping technology that has achieved solid scientific underpinnings. It is from this science base that recent progress has occurred in titanium powder injection molding. Much of the progress awaited development of the required particles with specific characteristics of particle size, particle shape, and purity. The production of titanium components by injection molding is stabilized by a good understanding of how each process variable impacts density and impurity level. As summarized here, recent research has isolated the four critical success factors in titanium metal powder injection molding (Ti-MIM) that must be simultaneously satisfied-density, purity, alloying, and microstructure. The critical role of density and impurities, and the inability to remove impurities with sintering, compels attention to starting Ti-MIM with high quality alloy powders. This article addresses the four critical success factors to rationalize Ti-MIM processing conditions to the requirements for demanding applications in aerospace and medical fields. Based on extensive research, a baseline process is identified and reported here with attention to linking mechanical properties to the four critical success factors.

Micro Dot Patterning on the Light Guide Panel Using Powder Blasting.

PubMed

Jang, Ho Su; Cho, Myeong Woo; Park, Dong Sam

2008-02-08

This study is to develop a micromachining technology for a light guidepanel(LGP) mold, whereby micro dot patterns are formed on a LGP surface by a singleinjection process instead of existing screen printing processes. The micro powder blastingtechnique is applied to form micro dot patterns on the LGP mold surface. The optimalconditions for masking, laminating, exposure, and developing processes to form the microdot patterns are first experimentally investigated. A LGP mold with masked micro patternsis then machined using the micro powder blasting method and the machinability of themicro dot patterns is verified. A prototype LGP is test- injected using the developed LGPmold and a shape analysis of the patterns and performance testing of the injected LGP arecarried out. As an additional approach, matte finishing, a special surface treatment method,is applied to the mold surface to improve the light diffusion characteristics, uniformity andbrightness of the LGP. The results of this study show that the applied powder blastingmethod can be successfully used to manufacture LGPs with micro patterns by just singleinjection using the developed mold and thereby replace existing screen printing methods.

Progress in Titanium Metal Powder Injection Molding

PubMed Central

German, Randall M.

2013-01-01

Metal powder injection molding is a shaping technology that has achieved solid scientific underpinnings. It is from this science base that recent progress has occurred in titanium powder injection molding. Much of the progress awaited development of the required particles with specific characteristics of particle size, particle shape, and purity. The production of titanium components by injection molding is stabilized by a good understanding of how each process variable impacts density and impurity level. As summarized here, recent research has isolated the four critical success factors in titanium metal powder injection molding (Ti-MIM) that must be simultaneously satisfied—density, purity, alloying, and microstructure. The critical role of density and impurities, and the inability to remove impurities with sintering, compels attention to starting Ti-MIM with high quality alloy powders. This article addresses the four critical success factors to rationalize Ti-MIM processing conditions to the requirements for demanding applications in aerospace and medical fields. Based on extensive research, a baseline process is identified and reported here with attention to linking mechanical properties to the four critical success factors. PMID:28811458

Modeling of process-induced residual stresses and resin flow behavior in resin transfer molded composites with woven fiber mats

NASA Astrophysics Data System (ADS)

Golestanian, Hossein

This research focuses on modeling Resin Transfer Molding process for manufacture of composite parts with woven fiber mats. Models are developed to determine cure dependent stiffness matrices for composites manufactured with two types of woven fiber mats. Five-harness carbon and eight-harness fiberglass mats with EPON 826 resin composites are considered. The models presented here take into account important material/process parameters with emphasis on; (1) The effects of cure-dependent resin mechanical properties, (2) Fiber undulation due to the weave of the fiber fill and warp bundles, and (3) Resin interaction with the fiber bundles at a microscopic scale. Cure-dependent mechanical properties were then used in numerical models to determine residual stresses and deformation in the composite parts. The complete cure cycle was modeled in these analyses. Also the cool down stage after the composite cure was analyzed. The effect of 5% resin shrinkage on residual stresses and deformations was also investigated. In the second part of the study, Finite Element models were developed to simulate mold filling in RTM processes. Resin flow in the fiber mats was modeled as flow through porous media. Physical models were also developed to investigate resin flow behavior into molds of rectangular and irregular shapes. Silicone fluids of 50 and 100 centistoke viscosities as well as EPON 826 epoxy resin were used in the mold filling experiments. The reinforcements consisted of several layers of woven fiberglass and carbon fiber mats. The effects of injection pressure, fluid viscosity, type of reinforcement, and mold geometry on mold filling times were investigated. Fiber mat permeabilities were determined experimentally for both types of reinforcements. Comparison of experimental and numerical resin front positions indicated the importance of edge effects in resin flow behavior in small cavities. The resin front positions agreed well for the rectangular mold geometry.

Validation of New Process Models for Large Injection-Molded Long-Fiber Thermoplastic Composite Structures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nguyen, Ba Nghiep; Jin, Xiaoshi; Wang, Jin

2012-02-23

This report describes the work conducted under the CRADA Nr. PNNL/304 between Battelle PNNL and Autodesk whose objective is to validate the new process models developed under the previous CRADA for large injection-molded LFT composite structures. To this end, the ARD-RSC and fiber length attrition models implemented in the 2013 research version of Moldflow was used to simulate the injection molding of 600-mm x 600-mm x 3-mm plaques from 40% glass/polypropylene (Dow Chemical DLGF9411.00) and 40% glass/polyamide 6,6 (DuPont Zytel 75LG40HSL BK031) materials. The injection molding was performed by Injection Technologies, Inc. at Windsor, Ontario (under a subcontract by Oakmore » Ridge National Laboratory, ORNL) using the mold offered by the Automotive Composite Consortium (ACC). Two fill speeds under the same back pressure were used to produce plaques under slow-fill and fast-fill conditions. Also, two gating options were used to achieve the following desired flow patterns: flows in edge-gated plaques and in center-gated plaques. After molding, ORNL performed measurements of fiber orientation and length distributions for process model validations. The structure of this report is as follows. After the Introduction (Section 1), Section 2 provides a summary of the ARD-RSC and fiber length attrition models. A summary of model implementations in the latest research version of Moldflow is given in Section 3. Section 4 provides the key processing conditions and parameters for molding of the ACC plaques. The validations of the ARD-RSC and fiber length attrition models are presented and discussed in Section 5. The conclusions will be drawn in Section 6.« less

Method for fabricating ceramic filaments and high density tape casting method

NASA Technical Reports Server (NTRS)

Collins, Jr., Earl R. (Inventor)

1990-01-01

An apparatus and method is disclosed for fabricating mats of ceramic material comprising preparing a slurry of ceramic particles in a binder/solvent, charging the slurry into a vessel, forcing the slurry from the vessel into spinneret nozzles, discharging the slurry from the nozzles into the path of airjets to enhance the sinuous character of the slurry exudate and to dry it, collecting the filaments on a moving belt so that the filaments overlap each other thereby forming a mat, curing the binder therein, compressing and sintering the mat to form a sintered mat, and crushing the sintered mat to produce filament shaped fragments. A process is also disclosed for producing a tape of densely packed, bonded ceramic particles comprising forming a slurry of ceramic particles and a binder/solvent, applying the slurry to a rotating internal molding surface, applying a large centrifugal force to the slurry to compress it and force excess binder/solvent from the particles, evaporating solvent and curing the binder thereby forming layers of bonded ceramic particles and cured binder, and separating the binder layer from the layer of particles. Multilayers of ceramic particles are cast in an analogous manner on top of previously formed layers. When all of the desired layers have been cast the tape is fired to produce a sintered tape. For example, a three-layer tape is produced having outer layers of highly compressed filament shaped fragments of strontium doped lanthanum (LSM) particles and a center layer of yttria stabilized zicronia (YSZ) particles.

Controle de la morphologie d'hydrogels poreux a partir de structures polymeres

NASA Astrophysics Data System (ADS)

Esquirol, Anne-Laure

This master thesis presents a new fabrication method to prepare hydrogels with fully interconnected and tunable macropore networks prepared with co-continuous polymer blends. The main contributions are: (1) a hydrogel fabrication process providing a high control over the average pore size diameter, their volume fraction and their interconnectivity; (2) the microstructural characterization of porous hydrogels with new techniques such as X-ray microtomography and (3) the preparation of porous gels with industrial equipment such as extruders and injection molding presses. The development and improvement of methods and techniques to prepare porous polymers and porous gels have been intensive areas of research in materials science over the past 20 years because of their potential use in fields as diverse as high performance membranes and filtration devices, supports for catalysis and biochemical reactions, encapsulating devices for drug release, and scaffolds for cells seeding and proliferation. For this last application, in tissue engineering, some typical parameters related to porosity must be rigorously controlled: (1) the average pore size diameter; (2) the pore volume fraction; (3) the pore interconnectivity. Porous hydrogels are excellent candidates due to their similarities with the extracellular matrix (composition, mechanical properties and diffusion properties). A certain number of methods and techniques have been developed and studied to prepare gels comprising microstructured 3-D networks of (more or less) interconnected pores (also called sometimes microfluidic gels or (macro)porous gels). Poly(L-lactide) (PLA) porous materials were realized from immiscible and co-continuous binary blends of polystyrene/poly(L-lactide) (PS/PLA) at 50/50 %vol prepared by different methods : (1) internal mixer (cubic samples with 0.8 mm sides) and (2) extrusion followed by injection molding which allows the fabrication of bars with superior dimensions (0.95 cm x 1.25 cm x 6.3 cm). Quiescent annealing of the binary blends was performed at 190 °C to tune the characteristic dimensions of the co-continuous morphology: (1) 0, 10, 30, 60 and 90 min for cubic samples and (2) 0, 10, 20 and 30 min for bars. Afterwards, the PLA phase has been isolated by a specific solvent extraction of the PS phase to obtain porous PLA molds. Gravimetric analysis have demonstrated a co-continuity superior to 95% for cubic samples and superior to 85% for the bars. This morphology was analyzed by scanning electron microscopy (SEM) for each annealing time (for the cubic samples). Image analysis performed on the SEM micrographs have demonstrated that the average pore diameter can range from 3 mum to over 400 mum and that the specific interfacial area ranges from 5800 cm-1 to 45 cm-1, for annealing times going from 0 min to 90 min). The porosity of the bars was observed by X-ray microtomography and shows that the average pore diameter ranges from 10 mum to 500 mum (annealing from 10 min to 30 min). Solutions of agar or alginate were subsequently injected into the PLA porous molds by using a manual injection system, followed by an in situ gelification. Visual inspections and optical microscope observations show a complete injection for molds with average pore sizes over 20 mum (cubic samples) and over 300 mum (for bars). These assumptions are also supported by the gels morphology characterization. The second polymer phase (PLA) was subsequently dissolved using a second selective solvent, leaving only the porous gel structures. X-ray microtomography analysis, which provide 2-D and 3-D images, have demonstrated that the morphologies of the porous gels are similar to the PLA molds microstructures. For example, porous gels prepared with cubic PLA molds annealed during 60 min, show an average pore size of about 285 mum (as compared to 200 mum for the PLA molds) and a specific interfacial area of 70 cm -1 (as compared to 100 cm-1 for the PLA molds). Similar results were obtained for the porous gels prepared with the porous PLA bars (qualitative observation). The effectiveness of two sterilization methods has been proven on nutrient agar (NA) and "Brain Heart Infusion" (BHI) with no bacterial colonies apparition. The first method is the freeze-drying followed by an oven treatment at 120 °C in a sterile environment. The porous gel morphology was characterized by X-ray microtomography before and after freeze-drying, and after rehydration, demonstrating the conservation of the macroscopic dimensions of the gels, of their morphologies and porosities. The second method is the successive baths in an ethanol solution. Finally mechanical compression tests have shown that porous gels, as can be expected, have a lower compressive resistance as compared to non-porous hydrogels. (Abstract shortened by UMI.).

Effect of mold designs on molten metal behaviour in high-pressure die casting

NASA Astrophysics Data System (ADS)

Ibrahim, M. D.; Rahman, M. R. A.; Khan, A. A.; Mohamad, M. R.; Suffian, M. S. Z. M.; Yunos, Y. S.; Wong, L. K.; Mohtar, M. Z.

2017-04-01

This paper presents a research study conducted in a local automotive component manufacturer that produces aluminium alloy steering housing local and global markets. This study is to investigate the effect of design modification of mold in die casting as to improve the production rate. Design modification is carried out on the casting shot of the mold. Computer flow simulation was carried out to study the flow of molten metal in the mold with respect to the mold design modification. The design parameters of injection speed, die temperature and clamping force has been included in the study. The result of the simulation showed that modifications of casting shot give significant impact towards the molten flow behaviour in casting process. The capabilities and limitations of die casting process simulation to conduct defect analysis had been optimized. This research will enhance the efficiency of the mass production of the industry of die casting with the understanding of defect analysis, which lies on the modification of the mold design, a way early in its stages of production.

Foam injection molding of poly(lactic acid) with physical blowing agents

NASA Astrophysics Data System (ADS)

Pantani, R.; Sorrentino, A.; Volpe, V.; Titomanlio, G.

2014-05-01

Foam injection molding uses environmental friendly blowing agents under high pressure and temperature to produce parts having a cellular core and a compact solid skin (the so-called "structural foam"). The addition of a supercritical gas reduces the part weight and at the same time improves some physical properties of the material through the promotion of a faster crystallization; it also leads to the reduction of both the viscosity and the glass transition temperature of the polymer melt, which therefore can be injection molded adopting lower temperatures and pressures. These aspects are of extreme interest for biodegradable polymers, which often present a very narrow processing window, with the suitable processing temperatures close to the degradation conditions. In this work, foam injection molding was carried out by an instrumented molding machine, able to measure the pressure evolution in different positions along the flow-path. The material adopted was a biodegradable polymer, namely the Poly(lactic acid), PLA. The effect of a physical blowing agent (PBA) on the viscosity was measured. The density reduction and the morphology of parts obtained by different molding conditions was assessed.

Rotationally Molded Liquid Crystalline Polymers

NASA Technical Reports Server (NTRS)

Rogers, Martin; Stevenson, Paige; Scribben, Eric; Baird, Donald; Hulcher, Bruce

2002-01-01

Rotational molding is a unique process for producing hollow plastic parts. Rotational molding offers advantages of low cost tooling and can produce very large parts with complicated shapes. Products made by rotational molding include water tanks with capacities up to 20,000 gallons, truck bed liners, playground equipment, air ducts, Nylon fuel tanks, pipes, toys, stretchers, kayaks, pallets, and many others. Thermotropic liquid crystalline polymers are an important class of engineering resins employed in a wide variety of applications. Thermotropic liquid crystalline polymers resins are composed of semi-rigid, nearly linear polymeric chains resulting in an ordered mesomorphic phase between the crystalline solid and the isotropic liquid. Ordering of the rigid rod-like polymers in the melt phase yields microfibrous, self-reinforcing polymer structures with outstanding mechanical and thermal properties. Rotational molding of liquid crystalline polymer resins results in high strength and high temperature hollow structures useful in a variety of applications. Various fillers and reinforcements can potentially be added to improve properties of the hollow structures. This paper focuses on the process and properties of rotationally molded liquid crystalline polymers.

Cartilage formation in the CELLS 'double bubble' hardware

NASA Technical Reports Server (NTRS)

Duke, P. J.; Arizpe, Jorge; Montufar-Solis, Dina

1991-01-01

The CELLS experiment scheduled to be flown on the first International Microgravity Laboratory is designed to study the effect of microgravity on the cartilage formation, by measuring parameters of growth in a differentiating cartilage cell culture. This paper investigates the conditions for this experiment by studying cartilage differentiation in the 'bubble exchange' hardware with the 'double bubble' design in which the bubbles are joined by a flange which also overlays the gasket. Four types of double bubbles (or double gas permeable membranes) were tested: injection-molded bubbles 0.01- and 0.005-in. thick, and compression molded bubbles 0.015- and 0.01-in. thick. It was found that double bubble membranes of 0.005- and 0.010-in. thickness supported cartilage differentiation, while the 0.015-in. bubbles did not. It was also found that nodule count, used in this study as a parameter, is not the best measure of the amount of cartilage differentiation.

Helmet of a laminate construction of polycarbonate and polysulfone polymeric material

NASA Technical Reports Server (NTRS)

Kosmo, Joseph J. (Inventor); Dawn, Frederic S. (Inventor)

1991-01-01

An article of laminate construction is disclosed which is comprised of an underlayer of polycarbonate polymer material to which is applied a chemically resistant outer layer of polysulfone. The layers which are joined by compression-heat molding, are molded to form the shape of a body protective shell such as a space helmet comprising a shell of polycarbonate, polysulfone laminate construction attached at its open end to a sealing ring adapted for connection to a space suit. The front portion of the shell provides a transparent visor for the helmet. An outer visor of polycarbonate polysulfone laminate construction is pivotally mounted to the sealing ring for covering the transparent visor portion of the shell during extravehicular activities. The polycarbonate under layer of the outer visor is coated on its inner surface with a vacuum deposit of gold to provide additional thermal radiation resistance.

Nde of Lumber and Natural Fiber Based Products with Air Coupled Ultrasound

NASA Astrophysics Data System (ADS)

Hsu, David K.; Utrata, David; Kuo, Monlin

2010-02-01

Due to the porous nature of wood and natural fiber based products, conventional fluid or gel coupled ultrasonic inspection is unsuitable. Air-coupled ultrasonic transmission scanning, being non-contact, is ideally suited for inspecting lumber, wood and natural fiber based products. We report here several successful applications of air-coupled ultrasound for the inspection of wood. Air-coupled ultrasonic scan at 120 kHz can easily detect "sinker-stock" lumber in which bacterial damage of ray tissue cells had occurred during anaerobic pond storage. Channels in ash lumber board caused by insect bore were imaged in transmission scan. Delamination and material inhomogeneities were mapped out in manufactured wood and natural fiber products including medium density fiberboards, compression molded shredded waste wood with formaldehyde resin, and acoustic panels molded with kenaf fibers. The study has demonstrated some of the capabilities of air-coupled ultrasound in the NDE of forest products.

Energy Saving Melting and Revert Reduction Technology (Energy-SMARRT): Light Metals Permanent Mold Casting

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fasoyinu, Yemi

2014-03-31

Current vehicles use mostly ferrous components for structural applications. It is possible to reduce the weight of the vehicle by substituting these parts with those made from light metals such as aluminum and magnesium. Many alloys and manufacturing processes can be used to produce these light metal components and casting is known to be most economical. One of the high integrity casting processes is permanent mold casting which is the focus of this research report. Many aluminum alloy castings used in automotive applications are produced by the sand casting process. Also, aluminum-silicon (Al-Si) alloys are the most widely used alloymore » systems for automotive applications. It is possible that by using high strength aluminum alloys based on an aluminum-copper (Al-Cu) system and permanent mold casting, the performance of these components can be enhanced significantly. This will also help to further reduce the weight. However, many technological obstacles need to be overcome before using these alloys in automotive applications in an economical way. There is very limited information in the open literature on gravity and low-pressure permanent mold casting of high strength aluminum alloys. This report summarizes the results and issues encountered during the casting trials of high strength aluminum alloy 206.0 (Al-Cu alloy) and moderate strength alloy 535.0 (Al-Mg alloy). Five engineering components were cast by gravity tilt-pour or low pressure permanent mold casting processes at CanmetMATERIALS (CMAT) and two production foundries. The results of the casting trials show that high integrity engineering components can be produced successfully from both alloys if specific processing parameters are used. It was shown that a combination of melt processing and mold temperature is necessary for the elimination of hot tears in both alloys.« less

Design of Revolute Joints for In-Mold Assembly Using Insert Molding.

PubMed

Ananthanarayanan, Arvind; Ehrlich, Leicester; Desai, Jaydev P; Gupta, Satyandra K

2011-12-01

Creating highly articulated miniature structures requires assembling a large number of small parts. This is a very challenging task and increases cost of mechanical assemblies. Insert molding presents the possibility of creating a highly articulated structure in a single molding step. This can be accomplished by placing multiple metallic bearings in the mold and injecting plastic on top of them. In theory, this idea can generate a multi degree of freedom structures in just one processing step without requiring any post molding assembly operations. However, the polymer material has a tendency to shrink on top of the metal bearings and hence jam the joints. Hence, until now insert molding has not been used to create articulated structures. This paper presents a theoretical model for estimating the extent of joint jamming that occurs due to the shrinkage of the polymer on top of the metal bearings. The level of joint jamming is seen as the effective torque needed to overcome the friction in the revolute joints formed by insert molding. We then use this model to select the optimum design parameters which can be used to fabricate functional, highly articulating assemblies while meeting manufacturing constraints. Our analysis shows that the strength of weld-lines formed during the in-mold assembly process play a significant role in determining the minimum joint dimensions necessary for fabricating functional revolute joints. We have used the models and methods described in this paper to successfully fabricate the structure for a minimally invasive medical robot prototype with potential applications in neurosurgery. To the best of our knowledge, this is the first demonstration of building an articulated structure with multiple degrees of freedom using insert molding.

[Effects of different excipients on properties of Tongsaimai mixture and pellet molding].

PubMed

Wang, Jin; Lv, Zhiyang; Wu, Xiaoyan; Di, Liuqing; Dong, Yu; Cai, Baochang

2011-01-01

To study preliminarily on the relationship between properties of the mixture composed of Tongsaimai extract and different excipients and pellet molding. The multivariate regression analysis was used to investigate the correlation of different mixture and pellet molding by measuring the cohesion, liquid-plastic limit of mixture, and the powder properties of pellets. The weighted coefficients of the powder properties were determined by analytic hierarchy process combined with criteria importance through intercriteria correlation. The results showed that liquid-plastic limit seemed to be a major factor, which had positive correlation with pellet molding, while cohesion had negative correlation with pellet molding in the measured range. The physical properties of the mixture has marked influence on pellet molding.

Index change of chalcogenide materials from precision glass molding processes

NASA Astrophysics Data System (ADS)

Deegan, J.; Walsh, K.; Lindberg, G.; Benson, R.; Gibson, D.; Bayya, S.; Sanghera, J.; Stover, E.

2015-05-01

With the increase in demand for infrared optics for thermal applications and the use of glass molding of chalcogenide materials to support these higher volume optical designs, an investigation of changes to the optical properties of these materials is required. Typical precision glass molding requires specific thermal conditions for proper lens molding of any type of optical glass. With these conditions a change (reduction) of optical index occurs after molding of all oxide glass types and it is presumed that a similar behavior will happen with chalcogenide based materials. We will discuss the effects of a typical molding thermal cycle for use with commercially and newly developed chalcogenide materials and show results of index variation from nominally established material data.

Optimal cure cycle design of a resin-fiber composite laminate

NASA Technical Reports Server (NTRS)

Hou, Jean W.; Sheen, Jeenson

1987-01-01

A unified computed aided design method was studied for the cure cycle design that incorporates an optimal design technique with the analytical model of a composite cure process. The preliminary results of using this proposed method for optimal cure cycle design are reported and discussed. The cure process of interest is the compression molding of a polyester which is described by a diffusion reaction system. The finite element method is employed to convert the initial boundary value problem into a set of first order differential equations which are solved simultaneously by the DE program. The equations for thermal design sensitivities are derived by using the direct differentiation method and are solved by the DE program. A recursive quadratic programming algorithm with an active set strategy called a linearization method is used to optimally design the cure cycle, subjected to the given design performance requirements. The difficulty of casting the cure cycle design process into a proper mathematical form is recognized. Various optimal design problems are formulated to address theses aspects. The optimal solutions of these formulations are compared and discussed.

Influence of injection temperatures and fiberglass compositions on mechanical properties of polypropylene

NASA Astrophysics Data System (ADS)

Keey, Tony Tiew Chun; Azuddin, M.

2017-06-01

Injection molding process appears to be one of the most suitable mass and cost efficiency manufacturing processes for polymeric parts nowadays due to its high efficiency of large scale production. When down-scaling the products and components, the limits of conventional injection molding process are reached. These constraints had initiated the development of conventional injection molding process into a new era of micro injection molding technology. In this study, fiberglass reinforced polypropylenes (PP) with various glass fiber percentage materials were used. The study start with fabrication of micro tensile specimens at three different injection temperature, 260°C, 270°C and 280°C for different percentage by weight of fiberglass reinforced PP. Then evaluate the effects of various injection temperatures on the tensile properties of micro tensile specimens. Different percentage by weight of fiberglass reinforced PP were tested as well and it was found that 20% fiberglass reinforced PP possessed the greatest percentage increase of tensile strength with increasing temperatures.

DIRECT INGOT PROCESS FOR PRODUCING URANIUM

DOEpatents

Leaders, W.M.; Knecht, W.S.

1960-11-15

A process is given in which uranium tetrafluoride is reduced to the metal with magnesium and in the same step the uranium metal formed is cast into an ingot. For this purpose a mold is arranged under and connected with the reaction bomb, and both are filled with the reaction mixture. The entire mixture is first heated to just below reaction temperature, and thereafter heating is restricted to the mixture in the mold. The reaction starts in the mold whereby heat is released which brings the rest of the mixture to reaction temperature. Pure uranium metal settles in the mold while the magnesium fluoride slag floats on top of it. After cooling, the uranium is separated from the slag by mechanical means.

Composite Structures and Materials Research at NASA Langley Research Center

NASA Technical Reports Server (NTRS)

Starnes, James H., Jr.; Dexter, H. Benson; Johnston, Norman J.; Ambur, Damodar R.; Cano, roberto J.

2003-01-01

A summary of recent composite structures and materials research at NASA Langley Research Center is presented. Fabrication research to develop low-cost automated robotic fabrication procedures for thermosetting and thermoplastic composite materials, and low-cost liquid molding processes for preformed textile materials is described. Robotic fabrication procedures discussed include ply-by-ply, cure-on-the-fly heated placement head and out-of-autoclave electron-beam cure methods for tow and tape thermosetting and thermoplastic materials. Liquid molding fabrication processes described include Resin Film Infusion (RFI), Resin Transfer Molding (RTM) and Vacuum-Assisted Resin Transfer Molding (VARTM). Results for a full-scale composite wing box are summarized to identify the performance of materials and structures fabricated with these low-cost fabrication methods.

Composite Structures and Materials Research at NASA Langley Research Center

NASA Technical Reports Server (NTRS)

Starnes, James H., Jr.; Dexter, H. Benson; Johnston, Norman J.; Ambur, Damodar R.; Cano, Roberto J.

2001-01-01

A summary of recent composite structures and materials research at NASA Langley Research Center is presented. Fabrication research to develop low-cost automated robotic fabrication procedures for thermosetting and thermoplastic composite materials, and low-cost liquid molding processes for preformed textile materials is described. Robotic fabrication procedures discussed include ply-by-ply, cure-on-the-fly heated placement head and out-of-autoclave electron-beam cure methods for tow and tape thermosetting and thermoplastic materials. Liquid molding fabrication processes described include Resin Film Infusion (RFI) Resin Transfer Molding (RTM) and Vacuum-Assisted Resin Transfer Molding (VARTM). Results for a full-scale composite wing box are summarized to identify the performance of materials and structures fabricated with these low-cost fabrication methods.

A thermoplastic polyimidesulfone

NASA Technical Reports Server (NTRS)

St.clair, T. L.; Yamaki, D. A.

1982-01-01

A polymer system has been prepared which has the excellent thermoplastic properties generally associated with polysulfones, and the solvent resistance and thermal stability of aromatic polyimides. This material, with improved processability over the base polyimide, can be processed in the 260-325 C range in such a manner as to yield high quality, tough unfilled moldings; strong, high-temperature-resistant adhesive bonds; and well consolidated, graphite-fiber-reinforced moldings (composities). The unfilled moldings have physical properties that are similar to aromatic polysulfones which demonstrates the potential as an engineering thermoplastic. The adhesive bonds exhibit excellent retention of initial strength levels even after thermal aging for 5000 hours at 232 C. The graphite-fiber-reinforced moldings have mechanical properties which makes this polymer attractive for the fabrication of structural composites.

Resin bleed improvement on surface mount semiconductor device

NASA Astrophysics Data System (ADS)

Rajoo, Indra Kumar; Tahir, Suraya Mohd; Aziz, Faieza Abdul; Shamsul Anuar, Mohd

2018-04-01

Resin bleed is a transparent layer of epoxy compound which occurs during molding process but is difficult to be detected after the molding process. Resin bleed on the lead on the unit from the focused package, SOD123, can cause solderability failure at end customer. This failed unit from the customer will be considered as a customer complaint. Generally, the semiconductor company has to perform visual inspection after the plating process to detect resin bleed. Mold chase with excess hole, split cavity & stepped design ejector pin hole have been found to be the major root cause of resin bleed in this company. The modifications of the mold chase, changing of split cavity to solid cavity and re-design of the ejector pin proposed were derived after a detailed study & analysis conducted to arrive at these solutions. The solutions proposed have yield good results during the pilot run with zero (0) occurrence of resin bleed for 3 consecutive months.

Neurologic and neuropsychiatric syndrome features of mold and mycotoxin exposure.

PubMed

Empting, L D

2009-01-01

Human exposure to molds, mycotoxins, and water-damaged buildings can cause neurologic and neuropsychiatric signs and symptoms. Many of these clinical features can partly mimic or be similar to classic neurologic disorders including pain syndromes, movement disorders, delirium, dementia, and disorders of balance and coordination. In this article, the author delineates the signs and symptoms of a syndrome precipitated by mold and mycotoxin exposure and contrasts and separates these findings neurodiagnostically from known neurologic diseases. This clinical process is designed to further the scientific exploration of the underlying neuropathophysiologic processes and to promote better understanding of effects of mold/mycotoxin/water-damaged buildings on the human nervous system and diseases of the nervous system. It is clear that mycotoxins can affect sensitive individuals, and possibly accelerate underlying neurologic/pathologic processes, but it is crucial to separate known neurologic and neuropsychiatric disorders from mycotoxin effects in order to study it properly.

Bio-inspired piezoelectric artificial hair cell sensor fabricated by powder injection molding

NASA Astrophysics Data System (ADS)

Han, Jun Sae; Oh, Keun Ha; Moon, Won Kyu; Kim, Kyungseop; Joh, Cheeyoung; Seo, Hee Seon; Bollina, Ravi; Park, Seong Jin

2015-12-01

A piezoelectric artificial hair cell sensor was fabricated by the powder injection molding process in order to make an acoustic vector hydrophone. The entire process of powder injection molding was developed and optimized for PMN-PZT ceramic powder. The artificial hair cell sensor, which consists of high aspect ratio hair cell and three rectangular mechanoreceptors, was precisely fabricated through the developed powder injection molding process. The density and the dielectric property of the fabricated sensor shows 98% of the theoretical density and 85% of reference dielectric property of PMN-PZT ceramic powder. With regard to homogeneity, three rectangular mechanoreceptors have the same dimensions, with 3 μm of tolerance with 8% of deviation of dielectric property. Packaged vector hydrophones measure the underwater acoustic signals from 500 to 800 Hz with -212 dB of sensitivity. Directivity of vector hydrophone was acquired at 600 Hz as analyzing phase differences of electric signals.

American Society of Composites, 32nd Technical Conference

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aitharaju, Venkat; Yu, Hang; Zhao, Selina

Resin transfer molding (RTM) has become increasingly popular for the manufacturing of composite parts. To enable high volume manufacturing and obtain good quality parts at an acceptable cost to automotive industry, accurate process simulation tools are necessary to optimize the process conditions. Towards that goal, General Motors and the ESI-group are involved in developing a state of the art process simulation tool for composite manufacturing in a project supported by the Department of Energy. This paper describes the modeling of various stages in resin transfer molding such as resin injection, resin curing, and part distortion. An instrumented RTM system locatedmore » at the General Motors Research and Development center was used to perform flat plaque molding experiments. The experimental measurements of fill time, in-mold pressure versus time, cure variation with time, and part deformation were compared with the model predictions and very good correlations were observed.« less

Heat Transfer in the LCCM Thermal Reserve Battery

DTIC Science & Technology

2009-09-01

and Molded Sheet 3M Corporation, Elkhart IN 46516 Microtherm Sheet Microtherm Inc., Alcoa TN 37701 AR5401 Flexible Blanket Aspen Aerogels, Inc...heated Microtherm side wall and axial thermal insulation 90.9 GPS9I 04/27/07 All batteries after GPS9H used six silicone rubber gaskets to form...pressure before ignition. Thin Microtherm side wrap next to cell stack. No pre- compression of any side wall insulation or side wall heat paper (– 40

Microfluidic fuel cell systems with embedded materials and structures and method thereof

DOEpatents

Morse, Jeffrey D.; Rose, Klint A; Maghribi, Mariam; Benett, William; Krulevitch, Peter; Hamilton, Julie; Graff, Robert T.; Jankowski, Alan

2005-07-26

Described herein is a process for fabricating microfluidic systems with embedded components in which micron-scale features are molded into the polymeric material polydimethylsiloxane (PDMS). Micromachining is used to create a mold master and the liquid precursors for PDMS are poured over the mold and allowed to cure. The PDMS is then removed form the mold and bonded to another material such as PDMS, glass, or silicon after a simple surface preparation step to form sealed microchannels.

Classification of buildings mold threat using electronic nose

NASA Astrophysics Data System (ADS)

Łagód, Grzegorz; Suchorab, Zbigniew; Guz, Łukasz; Sobczuk, Henryk

2017-07-01

Mold is considered to be one of the most important features of Sick Building Syndrome and is an important problem in current building industry. In many cases it is caused by the rising moisture of building envelopes surface and exaggerated humidity of indoor air. Concerning historical buildings it is mostly caused by outdated raising techniques among that is absence of horizontal isolation against moisture and hygroscopic materials applied for construction. Recent buildings also suffer problem of mold risk which is caused in many cases by hermetization leading to improper performance of gravitational ventilation systems that make suitable conditions for mold development. Basing on our research there is proposed a method of buildings mold threat classification using electronic nose, based on a gas sensors array which consists of MOS sensors (metal oxide semiconductor). Used device is frequently applied for air quality assessment in environmental engineering branches. Presented results show the interpretation of e-nose readouts of indoor air sampled in rooms threatened with mold development in comparison with clean reference rooms and synthetic air. Obtained multivariate data were processed, visualized and classified using a PCA (Principal Component Analysis) and ANN (Artificial Neural Network) methods. Described investigation confirmed that electronic nose - gas sensors array supported with data processing enables to classify air samples taken from different rooms affected with mold.

Rapid control of mold temperature during injection molding process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liparoti, Sara; Titomanlio, Giuseppe; Hunag, Tsang Min

2015-05-22

The control of mold surface temperature is an important factor that determines surface morphology and its dimension in thickness direction. It can also affect the frozen molecular orientation and the mold surface replicability in injection molded products. In this work, thin thermally active films were used to quickly control the mold surface temperature. In particular, an active high electrical conductivity carbon black loaded polyimide composites sandwiched between two insulating thin polymeric layers was used to condition the mold surface. By controlling the heating time, it was possible to control precisely the temporal variation of the mold temperature surface during themore » entire cycle. The surface heating rate was about 40°C/s and upon contact with the polymer the surface temperature decreased back to 40°C within about 5 s; the overall cycle time increased only slightly. The effect on cross section sample morphology of samples of iPP were analyzed and discussed on the basis of the recorded temperature evolution.« less

Analytical modeling and sensor monitoring for optimal processing of advanced textile structural composites by resin transfer molding

NASA Technical Reports Server (NTRS)

Loos, Alfred C.; Macrae, John D.; Hammond, Vincent H.; Kranbuehl, David E.; Hart, Sean M.; Hasko, Gregory H.; Markus, Alan M.

1993-01-01

A two-dimensional model of the resin transfer molding (RTM) process was developed which can be used to simulate the infiltration of resin into an anisotropic fibrous preform. Frequency dependent electromagnetic sensing (FDEMS) has been developed for in situ monitoring of the RTM process. Flow visualization tests were performed to obtain data which can be used to verify the sensor measurements and the model predictions. Results of the tests showed that FDEMS can accurately detect the position of the resin flow-front during mold filling, and that the model predicted flow-front patterns agreed well with the measured flow-front patterns.

Method for molding ceramic powders using a water-based gel casting process

DOEpatents

Jenny, Mark A.; Omalete, Ogbemi O.

1992-09-08

A method for molding ceramic powders comprises forming a slurry mixture including ceramic powder, a dispersant, and a monomer solution. The monomer solution includes at least one monofunctional monomer and at least one difunctional monomer, a free-radical initiator, and a aqueous solvent. The slurry mixture is transferred to a mold, and the mold containing the slurry mixture is heated to polymerize and crosslink the monomer and form a firm polymer-solvent gel matrix. The solid product may be removed from the mold and heated to first remove the solvent and subsequently remove the polymer, whereafter the product may be sintered.

Method and composition for molding low-density desiccant syntactic-foam articles

DOEpatents

Not Available

1981-12-07

These and other objects of the invention are achieved by a process for molding to size a desiccant syntactic foam article having a density of 0.2 to 0.9 g/cc and a moisture capacity of 1 to 12% by weight, comprising the steps of: charging a mold with a powdery mixture of an activated desiccant, microspheres and a thermosetting resin, the amount of the desiccant being sufficient to provide the required moisture capacity, and the amounts of the microspheres and resin being such that the microspheres/desiccant volume fraction exceeds the packing factor by an amount sufficient to substantially avoid shrinkage without causing excessively high molding pressures; covering the mold and heating the covered mold to a temperature and for an amount of time sufficient to melt the resin; and tightly closing the mold and heating the closed mold to a temperature and for an amount of time sufficient to cure the resin, and removing the resultant desiccant syntactic foam article from the mold. In a composition of matter aspect, the present invention provides desiccant syntactic foam articles, and a composition of matter for use in molding the same.

A study on the development of engineering plastic piston used in the shock absorber

NASA Astrophysics Data System (ADS)

Kim, Young-Ho; Bae, Won-Byong; Lim, Dong-Ju; Suh, Yun-Soo

1998-08-01

A piston is an important component of the shock absorber which determines comfortable riding and handling. Conventional piston is made of metal powder that is pressed in a mold, and then sintered at high temperatures below the melting point before machining processes such as drilling, sizing and teflon banding. This study aims at cutting down cost and weight, and improving the process by replacing the traditional sintering process used for manufacturing the shock absorber with the injection molding process adopting engineering plastics as raw material. To analyze the injection molding process, we used the commercial program, MOLDFLOW, and obtained an optimal combination of the process parameters. In addition, by comparing the engineering plastic piston with the metal powder piston through the formability and the performance experiments, we confirmed the availability of this alternative process suggested.

Cross Section of Legislative Approaches to Reducing Indoor Dampness and Mold

PubMed Central

Boese, Gerald W.

2017-01-01

Exposure to indoor dampness and mold is associated with numerous adverse respiratory conditions, including asthma. While no quantitative health-based threshold currently exists for mold, the conditions that support excessive dampness and mold are known and preventable; experts agree that controlling these conditions could lead to substantial savings in health care costs and improvement in public health. This article reviews a sample of state and local policies to limit potentially harmful exposures. Adoption of laws to strengthen building codes, specify dampness and mold in habitability laws, regulate mold contractors, and other legislative approaches are discussed, as are key factors supporting successful implementation. Communicating these lessons learned could accelerate the process for other jurisdictions considering similar approaches. Information about effectiveness of legislation as prevention is lacking; thus, evaluation could yield important information to inform the development of model state or local laws that significantly address mold as a public health concern. PMID:27977504

40 CFR 463.11 - Specialized definitions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... AND STANDARDS (CONTINUED) PLASTICS MOLDING AND FORMING POINT SOURCE CATEGORY Contact Cooling and... one plastics molding and forming process that uses contact cooling and heating water is the sum of the... heating water process and comes in contact with the plastic product over a period of one year. ...

40 CFR 463.10 - Applicability; description of the contact cooling and heating water subcategory.

Code of Federal Regulations, 2011 CFR

2011-07-01

... ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS PLASTICS MOLDING AND FORMING POINT... heating water subcategory are processes where process water comes in contact with plastic materials or plastic products for the purpose of heat transfer during plastics molding and forming. ...

40 CFR 63.544 - Standards for process fugitive sources.

Code of Federal Regulations, 2010 CFR

2010-07-01

...) Smelting furnace and dryer charging hoppers, chutes, and skip hoists; (2) Smelting furnace lead taps, and molds during tapping; (3) Smelting furnace slag taps, and molds during tapping; (4) Refining kettles; (5) Dryer transition pieces; and (6) Agglomerating furnace product taps. (b) Process fugitive emission...

40 CFR 463.21 - Specialized definitions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... AND STANDARDS PLASTICS MOLDING AND FORMING POINT SOURCE CATEGORY Cleaning Water Subcategory § 463.21... usage flow rate” for a plant with more than one plastics molding and forming process that uses cleaning... process and comes in contact with the plastic product over a period of one year. ...

40 CFR 463.31 - Specialized definitions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... AND STANDARDS PLASTICS MOLDING AND FORMING POINT SOURCE CATEGORY Finishing Water Subcategory § 463.31... usage flow rate” for a plant with more than one plastics molding and forming process that uses finishing... water process and comes in contact with the plastics product over a period of one year. ...

40 CFR 463.10 - Applicability; description of the contact cooling and heating water subcategory.

Code of Federal Regulations, 2010 CFR

2010-07-01

... ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS PLASTICS MOLDING AND FORMING POINT... heating water subcategory are processes where process water comes in contact with plastic materials or plastic products for the purpose of heat transfer during plastics molding and forming. ...

40 CFR 463.11 - Specialized definitions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... AND STANDARDS (CONTINUED) PLASTICS MOLDING AND FORMING POINT SOURCE CATEGORY Contact Cooling and... one plastics molding and forming process that uses contact cooling and heating water is the sum of the... heating water process and comes in contact with the plastic product over a period of one year. ...

Predicting and preventing mold spoilage of food products.

PubMed

Dagnas, Stéphane; Membré, Jeanne-Marie

2013-03-01

This article is a review of how to quantify mold spoilage and consequently shelf life of a food product. Mold spoilage results from having a product contaminated with fungal spores that germinate and form a visible mycelium before the end of the shelf life. The spoilage can be then expressed as the combination of the probability of having a product contaminated and the probability of mold growth (germination and proliferation) up to a visible mycelium before the end of the shelf life. For products packed before being distributed to the retailers, the probability of having a product contaminated is a function of factors strictly linked to the factory design, process, and environment. The in-factory fungal contamination of a product might be controlled by good manufacturing hygiene practices and reduced by particular processing practices such as an adequate air-renewal system. To determine the probability of mold growth, both germination and mycelium proliferation can be mathematically described by primary models. When mold contamination on the product is scarce, the spores are spread on the product and more than a few spores are unlikely to be found at the same spot. In such a case, models applicable for a single spore should be used. Secondary models can be used to describe the effect of intrinsic and extrinsic factors on either the germination or proliferation of molds. Several polynomial models and gamma-type models quantifying the effect of water activity and temperature on mold growth are available. To a lesser extent, the effect of pH, ethanol, heat treatment, addition of preservatives, and modified atmospheres on mold growth also have been quantified. However, mold species variability has not yet been properly addressed, and only a few secondary models have been validated for food products. Once the probability of having mold spoilage is calculated for various shelf lives and product formulations, the model can be implemented as part of a risk management decision tool.

Precision glass molding: Toward an optimal fabrication of optical lenses

NASA Astrophysics Data System (ADS)

Zhang, Liangchi; Liu, Weidong

2017-03-01

It is costly and time consuming to use machining processes, such as grinding, polishing and lapping, to produce optical glass lenses with complex features. Precision glass molding (PGM) has thus been developed to realize an efficient manufacture of such optical components in a single step. However, PGM faces various technical challenges. For example, a PGM process must be carried out within the super-cooled region of optical glass above its glass transition temperature, in which the material has an unstable non-equilibrium structure. Within a narrow window of allowable temperature variation, the glass viscosity can change from 105 to 1012 Pas due to the kinetic fragility of the super-cooled liquid. This makes a PGM process sensitive to its molding temperature. In addition, because of the structural relaxation in this temperature window, the atomic structure that governs the material properties is strongly dependent on time and thermal history. Such complexity often leads to residual stresses and shape distortion in a lens molded, causing unexpected changes in density and refractive index. This review will discuss some of the central issues in PGM processes and provide a method based on a manufacturing chain consideration from mold material selection, property and deformation characterization of optical glass to process optimization. The realization of such optimization is a necessary step for the Industry 4.0 of PGM.

Edgewise Compression Testing of STIPS-0 (Structurally Integrated Thermal Protection System)

NASA Technical Reports Server (NTRS)

Brewer, Amy R.

2011-01-01

The Structurally Integrated Thermal Protection System (SITPS) task was initiated by the NASA Hypersonics Project under the Fundamental Aeronautics Program to develop a structural load-carrying thermal protection system for use in aerospace applications. The initial NASA concept for SITPS consists of high-temperature composite facesheets (outer and inner mold lines) with a light-weight insulated structural core. An edgewise compression test was performed on the SITPS-0 test article at room temperature using conventional instrumentation and methods in order to obtain panel-level mechanical properties and behavior of the panel. Three compression loadings (10, 20 and 37 kips) were applied to the SITPS-0 panel. The panel behavior was monitored using standard techniques and non-destructive evaluation methods such as photogrammetry and acoustic emission. The elastic modulus of the SITPS-0 panel was determined to be 1.146x106 psi with a proportional limit at 1039 psi. Barrel-shaped bending of the panel and partial delamination of the IML occurred under the final loading.

Thermoplastic composites for veneering posterior teeth-a feasibility study.

PubMed

Gegauff, Anthony G; Garcia, Jose L; Koelling, Kurt W; Seghi, Robert R

2002-09-01

This pilot study was conducted to explore selected commercially-available thermoplastic composites that potentially had physical properties superior to currently available dental systems for restoring esthetic posterior crowns. Polyurethane, polycarbonate, and poly(ethylene/tetrafluoroethylene) (ETFE) composites and unfilled polyurethane specimens were injection molded to produce shapes adaptive to five standardized mechanical tests. The mechanical testing included abrasive wear rate, yield strength, apparent fracture toughness (strength ratio), flexural strength, and compressive strength. Compared to commercially available dental composites, abrasion wear rates were lower for all materials tested, yield strength was greater for the filled polycarbonates and filled polyurethane resins, fracture toughness testing was invalid (strength ratios were calculated for comparison of the pilot test materials), flexural strength was roughly similar except for the filled ETFE which was significantly greater, and compressive strength was lower. Commercially available thermoplastic resin composites, such as polyurethane, demonstrate the potential for development of an artificial crown material which exceeds the mechanical properties of currently available esthetic systems, if compressive strength can be improved.

Low-cost endoscopic third ventriculostomy simulator with mimetic endoscope.

PubMed

Garling, Richard Justin; Jin, Xin; Yang, Jianzhong; Khasawneh, Ahmad H; Harris, Carolyn Anne

2018-05-11

OBJECTIVE Hydrocephalus affects approximately 1 in 500 people in the US, yet ventricular shunting, the gold standard of treatment, has a nearly 85% failure rate. Endoscopic third ventriculostomy (ETV) is an alternative surgical approach for a specific subset of hydrocephalic patients, but can be limited by the inability of neurosurgical residents to practice prior to patient contact. The goal of this study was to create an affordable ETV model and endoscope for resident training. METHODS Open-source software was used to isolate the skull and brain from the CT and MR images of a 2-year-old boy with hydrocephalus. A 3D printer created the skull and a 3D mold of the brain. A mixture of silicone and silicone tactile mutator was used to cast the brain mold prior to subsequent compression and shearing modulus testing. A mimetic endoscope was then created from basic supplies and a 3D printed frame. A small cohort of neurosurgical residents and attending physicians evaluated the ETV simulator with mimetic endoscope. RESULTS The authors successfully created a mimetic endoscope and ETV simulator. After compression and shearing modulus testing, a silicone/Slacker ratio between 10:6 and 10:7 was found to be similar to that of human brain parenchyma. Eighty-seven percent of participants strongly agreed that the simulator was useful for resident training, and 93% strongly agreed that the simulator helped them understand how to orient themselves with the endoscope. CONCLUSIONS The authors created an affordable (US$123, excluding 3D printer), easy-to-use ETV simulator with endoscope. Previous models have required expensive software and costly operative endoscopes that may not be available to most residents. Instead, this attempt takes advantage of open-source software for the manipulation and fabrication of a patient-specific mold. This model can assist with resident development, allowing them to safely practice use of the endoscope in ETV.

Electrical and dielectric properties of foam injection-molded polypropylene/multiwalled carbon nanotube composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ameli, A.; Nofar, M.; Saniei, M.

A combination of high dielectric permittivity (ε′) and low dielectric loss (tan δ) is required for charge storage applications. In percolative systems such as conductive polymer composites, however, obtaining high ε′ and low tan δ is very challenging due to the sharp insulation-conduction transition near the threshold region. Due to the particular arrangement of conductive fillers induced by both foaming and injection molding processes, they may address this issue. Therefore, this work evaluates the application of foam injection molding process in fabricating polymer nanocomposites for energy storage. Polypropylene-multiwalled carbon nanotubes (PP-MWCNT) composites were prepared by melt mixing and foamed inmore » an injection molding process. Electrical conductivity (σ), ε′ and tan δ were then characterized. Also, scanning and transmission electron microscopy (SEM and TEM) was used to investigate the carbon nanotube’s arrangement as well as cellular morphology. The results showed that foam injection-molded composites exhibited highly superior dielectric properties to those of solid counterparts. For instance, foamed samples had ε′=68.3 and tan δ =0.05 (at 1.25 vol.% MWCNT), as opposed to ε′=17.8 and tan δ=0.04 in solid samples (at 2.56 vol.% MWCNT). The results of this work reveal that high performance dielectric nanocomposites can be developed using foam injection molding technologies for charge storage applications.« less

40 CFR 463.10 - Applicability; description of the contact cooling and heating water subcategory.

Code of Federal Regulations, 2014 CFR

2014-07-01

... ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS (CONTINUED) PLASTICS MOLDING AND... cooling and heating water subcategory are processes where process water comes in contact with plastic materials or plastic products for the purpose of heat transfer during plastics molding and forming. ...

EVALUATION OF POLLUTION PREVENTION TECHNIQUES TO REDUCE STYRENE EMISIONS FROM OPEN CONTACT MOLDING PROCESSES - VOLUME 1. FINAL REPORT

EPA Science Inventory

The report gives results of a study to evaluate several pollution prevention techniques that could be used to reduce styrene emissions from open molding processes in the fiberglass-reinforced
plastics/composites (FRP/C) and fiberglass boat building industries. Styrene emission...

EVALUATION OF POLLUTION PREVENTION TECHNIQUES TO REDUCE STYRENE EMISSIONS FROM OPEN CONTACT MOLDING PROCESSES - VOLUME 2. APPENDICES

EPA Science Inventory

The report gives results of a study to evaluate several pollution prevention techniques that could be used to reduce styrene emissions from open molding processes in the fiberglass-reinforced plastics/composites (FRP/C) and fiberglass boat building industries. Styrene emissions u...

EVALUATION OF POLLUTION PREVENTION OPTIONS TO REDUCE STYRENE EMISSIONS FROM FIBER-REINFORCED PLASTIC OPEN MOLDING PROCESSES

EPA Science Inventory

Pollution prevention (P2) options to reduce styrene emissions, such as new materials, and application equipment, are commercially available to the operators of open molding processes. However, information is lacking on the emissions reduction that these options can achieve. To me...

40 CFR 463.10 - Applicability; description of the contact cooling and heating water subcategory.

Code of Federal Regulations, 2012 CFR

2012-07-01

... ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS (CONTINUED) PLASTICS MOLDING AND... cooling and heating water subcategory are processes where process water comes in contact with plastic materials or plastic products for the purpose of heat transfer during plastics molding and forming. ...

Design and fabrication of optical homogenizer with micro structure by injection molding process

NASA Astrophysics Data System (ADS)

Chen, C.-C. A.; Chang, S.-W.; Weng, C.-J.

2008-08-01

This paper is to design and fabricate an optical homogenizer with hybrid design of collimator, toroidal lens array, and projection lens for beam shaping of Gaussian beam into uniform cylindrical beam. TracePro software was used to design the geometry of homogenizer and simulation of injection molding was preceded by Moldflow MPI to evaluate the mold design for injection molding process. The optical homogenizer is a cylindrical part with thickness 8.03 mm and diameter 5 mm. The micro structure of toroidal array has groove height designed from 12 μm to 99 μm. An electrical injection molding machine and PMMA (n= 1.4747) were selected to perform the experiment. Experimental results show that the optics homogenizer has achieved the transfer ratio of grooves (TRG) as 88.98% and also the optical uniformity as 68% with optical efficiency as 91.88%. Future study focuses on development of an optical homogenizer for LED light source.

Powder Injection Molding of Ceramic Engine Components for Transportation

NASA Astrophysics Data System (ADS)

Lenz, Juergen; Enneti, Ravi K.; Onbattuvelli, Valmikanathan; Kate, Kunal; Martin, Renee; Atre, Sundar

2012-03-01

Silicon nitride has been the favored material for manufacturing high-efficiency engine components for transportation due to its high temperature stability, good wear resistance, excellent corrosion resistance, thermal shock resistance, and low density. The use of silicon nitride in engine components greatly depends on the ability to fabricate near net-shape components economically. The absence of a material database for design and simulation has further restricted the engineering community in developing parts from silicon nitride. In this paper, the design and manufacturability of silicon nitride engine rotors for unmanned aerial vehicles by the injection molding process are discussed. The feedstock material property data obtained from experiments were used to simulate the flow of the material during injection molding. The areas susceptible to the formation of defects during the injection molding process of the engine component were identified from the simulations. A test sample was successfully injection molded using the feedstock and sintered to 99% density without formation of significant observable defects.

New alnico magnets fabricated from pre-alloyed gas-atomized powder through diverse consolidation techniques

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tang, W.; Zhou, L.; Kassen, A. G.

2015-05-25

Fine Alnico 8 spherical powder produced by gas atomization was consolidated through hot pressing (HP), hot isostatic pressing (HIP), and compression molding and subsequent sintering (CMS) techniques. The effects of different fabrication techniques and processing parameters on microstructure and magnetic properties were analyzed and compared. The HP, HIP, and CMS magnets exhibited different features in microstructures and magnetic properties. Magnetically annealed at 840°C for 10 min and subsequently tempered at 650°C for 5h and 580°C for 15h, the HIP sample achieved the best coercivity (H cj =1845 Oe) due to spinodally decomposed (SD) phases with uniform and well-faceted mosaic morphology.more » As a result, the CMS sample had a lower Hcj than HIP and HP samples, but a higher remanence and thus the best energy product (6.5 MGOe) due to preferential grain alignment induced by abnormal grain growth.« less

Tensile strength of ramie yarn (spinning by machine)/HDPE thermoplastic matrix composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Banowati, Lies, E-mail: liesbano@gmail.com; Hadi, Bambang K., E-mail: bkhadi@ae.itb.ac.id; Suratman, Rochim, E-mail: rochim@material.itb.ac.id

2016-03-29

Technological developments should be trooped to prevent a gap between technology and environmental sustainability, then it needs to be developed “Green technology”. In this research is making of green composites which use natural fiber ramie as reinforcement. Whereas the matrix used was HDPE (High Density Polyethylene) thermoplastic polymer which could be recycled and had a good formability and flexibility. The ramie yarns and fibers for unidirectional (0°) direction respectively were mixed with HDPE powder and processed using hot compression molding. The surface morphology was observed by SEM (Scanning Electrone Microscopy). Results showed that both tensile strength of the ramie fiber/HDPEmore » composites increased in comparison with the ramie yarn (spinning by machine)/HDPE composites. However, the ramie yarn (spinning by machine)/HDPE composites have a good producibility for wider application. Analysis of the test results using the Weibull distribution as approaches to modeling the reliability of the specimens.« less

Method and technique for installing light-weight, fragile, high-temperature fiber insulation

NASA Technical Reports Server (NTRS)

Patel, B. C. (Inventor)

1983-01-01

A method of installing fragile, light weight, high temperature fiber insulation, particularly where the insulation is to be used as a seal strip providing a high order of thermal barrier insulation is discussed. The process is based on provision of a strip of the mineral batting cut oversize by a predetermined amount, saturated in a fugitive polymer solution, compressed in a mold, dried and cured to form a rigidized batting material which is machined to required shape. The machine dimensions would normally be at least nominally less than the dimensions of the cavity to be sealed. After insertion in the cavity, which may be a wire-mesh seal enclosure, the apparatus is subjected to baking at a temperature sufficiently high to cause the resin to burn off cleanly, leaving the batting substantially in its original condition and expanded into the cavity or seal enclosure.

A method and technique for installing light-weight fragile, high-temperature fiber insulation

NASA Technical Reports Server (NTRS)

Ballantine, T. J. (Inventor)

1982-01-01

A method of installing fragile, light-weight, high-temperature fiber insulation, particularly where the insulation is to be used as a seal strip providing a high order of thermal barrier insulation is described. The process is based on provision of a strip of the mineral batting cut oversize by a predetermined amount, saturated in a fugitive polymer solution, compressed in a mold, dried and cured to form a rigidized batting material which may be machined to required shape. The machined dimensions would normally be at least nominally less than the dimensions of the cavity to be sealed. After insertion in the cavity, which may be a wire-mesh seal enclosure, the apparatus is subjected to baking at a temperature sufficiently high to cause the resin to burn off cleanly, leaving the batting substantially in its original condition and expanded into the cavity or seal enclosure.

Development of a low-cost, modified resin transfer molding process using elastomeric tooling and automated preform fabrication

NASA Technical Reports Server (NTRS)

Doane, William J.; Hall, Ronald G.

1992-01-01

This paper describes the design and process development of low-cost structural parts made by a modified resin transfer molding process. Innovative application of elastomeric tooling to increase laminate fiber volume and automated forming of fiber preforms are discussed, as applied to fabrication of a representative section of a cruise missile fuselage.

Bag molding processes

NASA Astrophysics Data System (ADS)

Slobodzinsky, A.

Features, materials, and techniques of vacuum, pressure, and autoclave FRP bag molding processes are described. The bags are used in sealed environments, inflated to flexibly force a curing FRP laminate to conform to a stiff mold form which defines the shape of the finished product. Densification is achieved as the bag presses out the voids and excess resin from the laminate, and consolidation occurs as the plies and adherends are bonded by the bag pressure. Curing techniques nominally involved room temperature or high temperature, and investigations of alternative techniques, such as induction, dielectric, microwave, xenon flash, UV, electron beam, and gamma radiation heating are proceeding. Polysulfone is the most common thermoplastic. Details are given of mold preparations, peel plies or release films and fabrics, bagging techniques, and reusable venting blankets and silicone rubber bags.

Multicomponent micropatterned sol-gel materials by capillary molding

NASA Astrophysics Data System (ADS)

Lochhead, Michael J.; Yager, Paul

1997-10-01

A physically and chemically benign method for patterning multiple sol-gel materials onto a single substrate is described. Structures are demonstrated for potential micro- optical chemical sensor, biosensor, and waveguiding applications. Fabrication is based on the micro molding in capillaries (MIMIC) approach. A novel mold design allows several sols to be cast simultaneously. Closely spaced, organically modified silica ridges containing fluorescent dyes are demonstrated. Ridges have cross sectional dimensions from one to 50 micrometers and are centimeters in length. Processing issues, particularly those related to mold filling, are discussed in detail. Because sol-gel MIMIC avoids the harsh physical and chemical environments normally associated with patterning, the approach allows full exploitation of sol- gel processing advantages, such as the ability to entrap sensitive organic dopant molecules in the sol-gel matrix.

Fiber optic strain monitoring of textile GFRP during RTM molding and fatigue tests by using embedded FBG sensors

NASA Astrophysics Data System (ADS)

Kosaka, Tatsuro; Osaka, Katsuhiko; Nakakita, Satoru; Fukuda, Takehito

2003-08-01

This paper describes cure and health monitoring of glass fiber reinforced plastics (GFRP) textile composites both during a resin transfer molding (RTM) process and in loading tests. Carbon fiber reinforced plastics (CFRP) textile composites also were used for a comparative study. Fiber Bragg grating (FBG) fiber optic sensors were embedded in FRP to monitor internal strain. From the results of cure monitoring, it was found that the embedded FBG sensors were useful to know when cured resin constrained fibers. It also appeared that specimens were subjected to friction stress resulted from difference of coefficient of thermal expansion between FRP and a stainless steel mold in cooling process of RTM molding. After the molding, tensile and fatigue tests were conducted. The results of tensile tests showed that output of the embedded FBG sensors agreed well that of surface-bonded strain gauges despite deterioration of reflected spectra form the sensors. From the results of fatigue tests, the FBG sensors showed good status until 100,000 cycles when specimens had no damage. From these results, it can be concluded that embedded FBG sensors have good capability of monitoring internal strain in textile FRP both during RTM process and in service.

Survey of molds, yeast and Alicyclobacillus spp. from a concentrated apple juice productive process.

PubMed

de Cássia Martins Salomão, Beatriz; Muller, Chalana; do Amparo, Hudson Couto; de Aragão, Gláucia Maria Falcão

2014-01-01

Bacteria and molds may spoil and/or contaminate apple juice either by direct microbial action or indirectly by the uptake of metabolites as off-flavours and toxins. Some of these microorganisms and/or metabolites may remain in the food even after extensive procedures. This study aim to identify the presence of molds (including heat resistant species) and Alicyclobacillus spp., during concentrated apple juice processing. Molds were isolated at different steps and then identified by their macroscopic and microscopic characteristics after cultivation on standard media at 5, 25 and 37 °C, during 7 days. Among the 19 isolated found, 63% were identified as Penicillium with 50% belonging to the P. expansum specie. With regards to heat resistant molds, the species Neosartorya fischeri, Byssochlamys fulva and also the genus Eupenicillium sp., Talaromyces sp. and Eurotium sp. were isolated. The thermoacidophilic spore-forming bacteria were identified as A. acidoterrestris by a further investigation based on 16S rRNA sequence similarity. The large contamination found indicates the need for methods to eliminate or prevent the presence of these microorganisms in the processing plants in order to avoid both spoilage of apple juice and toxin production.

Using template/hotwire cutting to demonstrate moldless composite fabrication

NASA Technical Reports Server (NTRS)

Coleman, J. Mario

1990-01-01

The objective of this experiment is to provide a simple, inexpensive composite fabrication technique which can be easily performed with a minimum of equipment and facilities. This process eliminates expensive female molds and uses only male molds which are easily formed from foam blocks. Once the mold is shaped, it is covered with fiberglass and becomes a structural component of the product.

Rapid fabrication method of a microneedle mold with controllable needle height and width.

PubMed

Lin, Yen-Heng; Lee, I-Chi; Hsu, Wei-Chieh; Hsu, Ching-Hong; Chang, Kai-Ping; Gao, Shao-Syuan

2016-10-01

The main issue of transdermal drug delivery is that macromolecular drugs cannot diffuse through the stratum corneum of skin. Many studies have pursued micro-sized needles encapsulated with drugs to overcome this problem, as these needles can pierce the stratum corneum and allow drugs to enter the circulatory system of the human body. However, most microneedle fabrication processes are time-consuming and require expensive equipment. In this study, we demonstrate a rapid method for fabricating a microneedle mold using drawing lithography and a UV-cured resin. The mold was filled with a water-soluble material, polyvinylpyrrolidone (PVP), which was then demolded to produce a water-soluble microneedle array. The results of an in vitro skin insertion test using PVP microneedles and pig ear skin demonstrated the feasibility of the microneedle mold. In addition, by controlling the viscosity of the UV-cured resin through various heat treatments, microneedles with different heights and aspect ratios were produced. Compared with other methods, this technology significantly simplifies and accelerates the mold fabrication process. In addition, the required equipment is relatively simple and inexpensive. Through this technology, we can rapidly fabricate microneedle molds with controllable dimensions for various applications.

Casting materials

DOEpatents

Chaudhry, Anil R [Xenia, OH; Dzugan, Robert [Cincinnati, OH; Harrington, Richard M [Cincinnati, OH; Neece, Faurice D [Lyndurst, OH; Singh, Nipendra P [Pepper Pike, OH

2011-06-14

A foam material comprises a liquid polymer and a liquid isocyanate which is mixed to make a solution that is poured, injected or otherwise deposited into a corresponding mold. A reaction from the mixture of the liquid polymer and liquid isocyanate inside the mold forms a thermally collapsible foam structure having a shape that corresponds to the inside surface configuration of the mold and a skin that is continuous and unbroken. Once the reaction is complete, the foam pattern is removed from the mold and may be used as a pattern in any number of conventional casting processes.

Improved Sand-Compaction Method for Lost-Foam Metal Casting

NASA Technical Reports Server (NTRS)

Bakhtiyarov, Sayavur I.; Overfelt, Ruel A.

2008-01-01

An improved method of filling a molding flask with sand and compacting the sand around a refractory-coated foam mold pattern has been developed for incorporation into the lost-foam metal-casting process. In comparison with the conventional method of sand filling and compaction, this method affords more nearly complete filling of the space around the refractory-coated foam mold pattern and more thorough compaction of the sand. In so doing, this method enables the sand to better support the refractory coat under metallostatic pressure during filling of the mold with molten metal.

Deposition of aluminum coatings on bio-composite laminates

NASA Astrophysics Data System (ADS)

Boccarusso, L.; Viscusi, A.; Durante, M.; Astarita, A.; De Fazio, D.; Sansone, R.; Caraviello, A.; Carrino, L.

2018-05-01

As a result of the increasing environmental awareness, the concern for environmental sustainability and the growing global waste problem, the interest of bio-composites materials is growing rapidly in the last years in order to use them in various engineering fields. Tremendous advantages and opportunities are associated with the use of these materials. On the other hand, some issues are related to the superficial properties of the bio-laminates, in particular the wear properties, the flame resistance and the aesthetic appearance have to be improved in order to extend the application fields of these materials. Aiming to these goals this paper deals with the study of the deposition of aluminum coating through cold spray process on hemp/PLA bio-composites manufactured by using the compression molding technique. Therefore, SEM observations, roughness analyses, bending tests, pin on disk and scratch tests were carried out in order to study the feasibility of the process and to investigate on the properties of the coated samples. The experimental results proved that when the process parameters of the deposition process are properly set, no damages are induced in the composite panel and that the aluminum coating, under specific load conditions, resulted to be able to protect the substrate.

Arrays of hollow out-of-plane microneedles made by metal electrodeposition onto solvent cast conductive polymer structures

NASA Astrophysics Data System (ADS)

Mansoor, I.; Liu, Y.; Häfeli, U. O.; Stoeber, B.

2013-08-01

Transdermal drug delivery using microneedles is a technique to potentially replace hypodermic needles for injection of many vaccines and drugs. Fabrication of hollow metallic microneedles so far has been associated with time-consuming steps that restrict batch production of these devices. Here, we are presenting a novel method for making metallic microneedles with any desired height, spacing, and lumen size. In our process, we use solvent casting to coat a mold, which contains an array of pillars, with a conductive polymer composite layer. The conductive layer is then used as a seed layer in a metal electrodeposition process. To characterize the process, the conductivity of the polymer composite with respect to different filler concentrations was investigated. In addition, plasma etching of the polymer was characterized. The electroplating process was also studied further to control the thickness of the microneedle array plate. The strength of the microneedle devices was evaluated through a series of compression tests, while their performance for transdermal drug delivery was tested by injection of 2.28 µm fluorescent microspheres into animal skin. The fabricated metallic microneedles seem appropriate for subcutaneous delivery of drugs and microspheres.

Sensory quality of Camembert-type cheese: Relationship between starter cultures and ripening molds.

PubMed

Galli, Bruno Domingues; Martin, José Guilherme Prado; da Silva, Paula Porrelli Moreira; Porto, Ernani; Spoto, Marta Helena Fillet

2016-10-03

Starter cultures and ripening molds used in the manufacture of moldy cheese aimed at obtaining characteristic flavors and textures considerably differ among dairy industries. Thus, the study of variables inherent to the process and their influence on sensory patterns in cheese can improve the standardization and control of the production process. The aim of this work was to study the influence of three different variables on the sensory quality of Camembert-type cheese: type of lactic bacteria, type of ripener molds and inoculation method. Batches of Camembert-type cheese were produced using O or DL-type mesophilic starter culture, ripened with Penicillium camemberti or Penicillium candidum and mold inoculation was made directly into the milk or by spraying. All batches were sensorially evaluated using Quantitative Descriptive Analysis (QDA) with panelists trained for various attributes. Among the combinations analyzed, those resulting in more typical Camembert-type cheese were those using O-type mesophilic starter culture and P. candidum maturation mold directly applied into the milk or sprayed and those using DL-type mesophilic starter and P. camemberti ripener mold applied by surface spraying. These results demonstrate, therefore, that the combination of different ripener molds, inoculation methods and starter cultures directly influences the sensory quality of Camembert-type cheese, modifying significantly its texture, appearance, aroma and taste. Copyright © 2016 Elsevier B.V. All rights reserved.

Chemically-bonded brick production based on burned clay by means of semidry pressing

NASA Astrophysics Data System (ADS)

Voroshilov, Ivan; Endzhievskaya, Irina; Vasilovskaya, Nina

2016-01-01

We presented a study on the possibility of using the burnt rocks of the Krasnoyarsk Territory for production of chemically-bonded materials in the form of bricks which are so widely used in multistory housing and private house construction. The radiographic analysis of the composition of burnt rock was conducted and a modifier to adjust the composition uniformity was identified. The mixing moisture content was identified and optimal amount at 13-15% was determined. The method of semidry pressing has been chosen. The process of obtaining moldings has been theoretically proved; the advantages of chemically-bonded wall materials compared to ceramic brick were shown. The production of efficient artificial stone based on material burnt rocks, which is comparable with conventionally effective ceramic materials or effective with cell tile was proved, the density of the burned clay-based cell tile makes up to 1630-1785 kg m3, with compressive strength of 13.6-20.0 MPa depending on the compression ratio and cement consumption, frost resistance index is F50, and the thermal conductivity in the masonry is λ = 0,459-0,546 W m * °C. The clear geometric dimensions of pressed products allow the use of the chemically-bonded brick based on burnt clay as a facing brick.

Superior Mechanical Properties of Epoxy Composites Reinforced by 3D Interconnected Graphene Skeleton.

PubMed

Ni, Ya; Chen, Lei; Teng, Kunyue; Shi, Jie; Qian, Xiaoming; Xu, Zhiwei; Tian, Xu; Hu, Chuansheng; Ma, Meijun

2015-06-03

Epoxy-based composites reinforced by three-dimensional graphene skeleton (3DGS) were fabricated in resin transfer molding method with respect to the difficulty in good dispersion and arrangement of graphene sheets in composites by directly mixing graphene and epoxy. 3DGS was synthesized in the process of self-assembly and reduction with poly(amidoamine) dendrimers. In the formation of 3DGS, graphene sheets were in good dispersion and ordered state, which resulted in exceptional mechanical properties and thermal stability for epoxy composites. For 3DGS/epoxy composites, the tensile and compressive strengths significantly increased by 120.9% and 148.3%, respectively, as well as the glass transition temperature, which increased by a notable 19 °C, unlike the thermal exfoliation graphene/epoxy composites via direct-mixing route, which increased by only 0.20 wt % content of fillers. Relative to the graphene/epoxy composites in direct-mixing method mentioned in literature, the increase in tensile and compressive strengths of 3DGS/epoxy composites was at least twofold and sevenfold, respectively. It can be expected that 3DGS, which comes from preforming graphene sheets orderly and dispersedly, would replace graphene nanosheets in polymer nanocomposite reinforcement and endow composites with unique structure and some unexpected performance.

Fatigue resistance of unnotched and post impact(+/- 30 deg/0 deg) 3-D braided composites

NASA Technical Reports Server (NTRS)

Portanova, Marc A.

1994-01-01

The fatigue resistance of a multiaxial braided (3-D) graphite/expoxy composite in both unnotched and post impacted conditions has been evaluated. The material tested is a (+/- 30/0 deg) multiaxial braid constructed from AS4/12K tow graphite fibers and British Petroleum E905L epoxy resin. These materials were braided as dry preforms and the epoxy was added using a resin transfer molding process (RTM). The unnotched and post-impact specimens were tested in compression-compression fatigue at 10 Hz with a stress ratio of R=10. The unnotched tension-tension fatigue specimens were tested at S Hz with a stress ration of R=0.1. Damage initiation and growth was documented through the application of radiography and ultrasonic through transmission (C-scans). Visible inspection of surface and edge damage was also noted to describe the initiation and progression of damage in these materials. The mechanisms leading to damage initiation were established and failure modes were determined. Stiffness and strength degradation were measured as a function of applied cycles. These 3-D braided composite results were compared to strain levels currently used to design primary structure in commercial aircraft composite components made from prepreg tape and autoclave cured.

Silicon micro-mold and method for fabrication

DOEpatents

Morales, Alfredo M.

2005-01-11

The present invention describes a method for rapidly fabricating a robust 3-dimensional silicon micro-mold for use in preparing complex metal micro-components. The process begins by depositing a conductive metal layer onto one surface of a silicon wafer. A thin photoresist and a standard lithographic mask are then used to transfer a trace image pattern onto the opposite surface of the wafer by exposing and developing the resist. The exposed portion of the silicon substrate is anisotropically etched through the wafer thickness down to conductive metal layer to provide an etched pattern consisting of a series of rectilinear channels and recesses in the silicon which serve as the silicon micro-mold. Microcomponents are prepared with this mold by first filling the mold channels and recesses with a metal deposit, typically by electroplating, and then removing the silicon micro-mold by chemical etching.

Silicon micro-mold

DOEpatents

Morales, Alfredo M [Livermore, CA

2006-10-24

The present invention describes a method for rapidly fabricating a robust 3-dimensional silicon-mold for use in preparing complex metal micro-components. The process begins by depositing a conductive metal layer onto one surface of a silicon wafer. A thin photoresist and a standard lithographic mask are then used to transfer a trace image pattern onto the opposite surface of the wafer by exposing and developing the resist. The exposed portion of the silicon substrate is anisotropically etched through the wafer thickness down to conductive metal layer to provide an etched pattern consisting of a series of rectilinear channels and recesses in the silicon which serve as the silicon micro-mold. Microcomponents are prepared with this mold by first filling the mold channels and recesses with a metal deposit, typically by electroplating, and then removing the silicon micro-mold by chemical etching.

Developing the elastic modulus measurement of asphalt concrete using the compressive strength test

NASA Astrophysics Data System (ADS)

Setiawan, Arief; Suparma, Latif Budi; Mulyono, Agus Taufik

2017-11-01

Elastic modulus is a fundamental property of an asphalt mixture. An analytical method of the elastic modulus is needed to determine the thickness of flexible pavement. It has a role as one of the input values on a stress-strain analysis in the finite element method. The aim of this study was to develop the measurement of the elastic modulus by using compressive strength testing. This research used a set of specimen mold tool and Delta Dimensi software to record strain changes occurring in the proving ring of compression machine and the specimens. The elastic modulus of the five types of aggregate gradation and 2 types of asphalt were measured at optimum asphalt content. Asphalt Cement 60/70 and Elastomer Modified Asphalt (EMA) were used as a binder. Manufacturing success indicators of the specimens used void-in-the-mix (VIM) 3-5 % criteria. The success rate of the specimen manufacturing was more than 76%. Thus, the procedure and the compressive strength test equipment could be used for the measurement of the elastic modulus. The aggregate gradation and asphalt types significantly affected the elastic modulus of the asphalt concrete.

Minimally invasive repair of pectus carinatum and how to deal with complications

PubMed Central

Aragone, Xavier; Blanco, Javier Borbore; Ciano, Alejandro; Abramson, Leonardo

2016-01-01

While less common than pectus excavatum, pectus carinatum is also a chest wall deformity affecting males in higher proportion than women. Patient requests for a solution of this disease occur especially during the growth spurt of puberty when this malformation becomes more obvious and difficult to conceal. Those people suffering from pectus carinatum are very likely subject to behavioral changes and negative personality impacts. By compressing the protruding anterior region of the chest wall we achieve correction of the chest contour and simultaneous lateral expansion of the depressed costochondral arches. This original technique and the procedure to apply it fit within the category of minimally invasive surgery. The compression system acts in a way similar to that of orthodontic braces. Two rectangular fixation plates are fixed to the compression strut with screws. The plates have threaded holes along a groove in the central portion, and two holes at both ends used to attach them to the ribs by means of steel wire suture. The compression strut has to be modified into a convex shape to adapt it to the particular characteristics of the patient’s malformation. This molding is done using benders designed as part of the procedure. PMID:29078492

Minimally invasive repair of pectus carinatum and how to deal with complications.

PubMed

Abramson, Horacio; Aragone, Xavier; Blanco, Javier Borbore; Ciano, Alejandro; Abramson, Leonardo

2016-01-01

While less common than pectus excavatum, pectus carinatum is also a chest wall deformity affecting males in higher proportion than women. Patient requests for a solution of this disease occur especially during the growth spurt of puberty when this malformation becomes more obvious and difficult to conceal. Those people suffering from pectus carinatum are very likely subject to behavioral changes and negative personality impacts. By compressing the protruding anterior region of the chest wall we achieve correction of the chest contour and simultaneous lateral expansion of the depressed costochondral arches. This original technique and the procedure to apply it fit within the category of minimally invasive surgery. The compression system acts in a way similar to that of orthodontic braces. Two rectangular fixation plates are fixed to the compression strut with screws. The plates have threaded holes along a groove in the central portion, and two holes at both ends used to attach them to the ribs by means of steel wire suture. The compression strut has to be modified into a convex shape to adapt it to the particular characteristics of the patient's malformation. This molding is done using benders designed as part of the procedure.

Flexible Nonstick Replica Mold for Transfer Printing of Ag Ink.

PubMed

Lee, Bong Kuk; Yu, Han Young; Kim, Yarkyeon; Yoon, Yong Sun; Jang, Won Ik; Do, Lee-Mi; Park, Ji-Ho; Park, Jaehoon

2016-03-01

We report the fabrication of flexible replica molds for transfer printing of Ag ink on a rigid glass substrate. As mold precursors, acrylic mixtures were prepared from silsesquioxane-based materials, silicone acrylate, poly(propylene glycol) diacrylate, 3,3,4,4,5,5,6,6,7,7,8,8, 9,9,10,10,10-heptadecafluorodecyl methacrylate, and photoinitiator. By using these materials, the replica molds were fabricated from a silicon master onto a flexible substrate by means of UV-assisted molding process at room temperature. The wettability of Ag ink decreased with increase in the water contact angle of replica molds. On the other hand, the transfer rate of Ag ink onto adhesive-modified substrates increased with increase in the water contact angle of replica molds. Transferred patterns were found to be thermally stable on the photocurable adhesive layer, whereas Ag-ink patterns transferred on non-photocurable adhesives were distorted by thermal treatment. We believe that these characteristics of replica molds and adhesives offer a new strategy for the development of the transfer printing of solution-based ink materials.

Textile composite processing science

NASA Technical Reports Server (NTRS)

Loos, Alfred C.; Hammond, Vincent H.; Kranbuehl, David E.; Hasko, Gregory H.

1993-01-01

A multi-dimensional model of the Resin Transfer Molding (RTM) process was developed for the prediction of the infiltration behavior of a resin into an anisotropic fiber preform. Frequency dependent electromagnetic sensing (FDEMS) was developed for in-situ monitoring of the RTM process. Flow visualization and mold filling experiments were conducted to verify sensor measurements and model predictions. Test results indicated good agreement between model predictions, sensor readings, and experimental data.

Fabrication of long-focal-length plano-convex microlens array by combining the micro-milling and injection molding processes.

PubMed

Chen, Lei; Kirchberg, Stefan; Jiang, Bing-Yan; Xie, Lei; Jia, Yun-Long; Sun, Lei-Lei

2014-11-01

A uniform plano-convex spherical microlens array with a long focal length was fabricated by combining the micromilling and injection molding processes in this work. This paper presents a quantitative study of the injection molding process parameters on the uniformity of the height of the microlenses. The variation of the injection process parameters, i.e., barrel temperature, mold temperature, injection speed, and packing pressure, was found to have a significant effect on the uniformity of the height of the microlenses, especially the barrel temperature. The filling-to-packing switchover point is also critical to the uniformity of the height of the microlenses. The optimal uniformity was achieved when the polymer melts completely filled the mold cavity, or even a little excessively filled the cavity, during the filling stage. In addition, due to the filling resistance, the practical filling-to-packing switchover point can vary with the change of the filling processing conditions and lead to a non-negligible effect on the uniformity of the height of the microlenses. Furthermore, the effect of injection speed on the uniformity of the height of the microlenses was analyzed in detail. The results indicated that the effect of injection speed on the uniformity of the height of the microlenses is mainly attributed to the two functions of injection speed: transferring the filling-to-packing switchover point and affecting the distribution of residual flow stress in the polymer melt.

Simulation-based process windows simultaneously considering two and three conflicting criteria in injection molding

PubMed Central

Rodríguez-Yáñez, Alicia Berenice; Méndez-Vázquez, Yaileen

2014-01-01

Process windows in injection molding are habitually built with only one performance measure in mind. In reality, a more realistic picture can be obtained when considering multiple performance measures at a time, especially in the presence of conflict. In this work, the construction of process windows for injection molding (IM) is undertaken considering two and three performance measures in conflict simultaneously. The best compromises between the criteria involved are identified through the direct application of the concept of Pareto-dominance in multiple criteria optimization. The aim is to provide a formal and realistic strategy to set processing conditions in IM operations. The resulting optimization approach is easily implementable in MS Excel. The solutions are presented graphically to facilitate their use in manufacturing plants. PMID:25530927

Simulation-based process windows simultaneously considering two and three conflicting criteria in injection molding.

PubMed

Rodríguez-Yáñez, Alicia Berenice; Méndez-Vázquez, Yaileen; Cabrera-Ríos, Mauricio

2014-01-01

Process windows in injection molding are habitually built with only one performance measure in mind. In reality, a more realistic picture can be obtained when considering multiple performance measures at a time, especially in the presence of conflict. In this work, the construction of process windows for injection molding (IM) is undertaken considering two and three performance measures in conflict simultaneously. The best compromises between the criteria involved are identified through the direct application of the concept of Pareto-dominance in multiple criteria optimization. The aim is to provide a formal and realistic strategy to set processing conditions in IM operations. The resulting optimization approach is easily implementable in MS Excel. The solutions are presented graphically to facilitate their use in manufacturing plants.

NASA. Langley Research Center dry powder towpreg system

NASA Technical Reports Server (NTRS)

Baucom, Robert M.; Marchello, Joseph M.

1990-01-01

Dry powder polymer impregnated carbon fiber tows were produced for preform weaving and composite materials molding applications. In the process, fluidized powder is deposited on spread tow bundles and melted on the fibers by radiant heating to adhere the polymer to the fiber. Unit design theory and operating correlations were developed to provide the basis for scale up of the process to commercial operation. Special features of the operation are the pneumatic tow spreader, fluidized bed, resin feeder, and quality control system. Bench scale experiments, at tow speeds up to 50 cm/sec, demonstrated that process variables can be controlled to produce weavable LARC-TPI carbon fiber towpreg. The towpreg made by the dry powder process was formed into unidirectional fiber moldings and was woven and molded into preform material of good quality.

Distortion-free foamed-plastic parts

NASA Technical Reports Server (NTRS)

Hogenson, P. A.; Jackson, R. G.

1979-01-01

In process for molding foamed-plastic products, gases that are formed as byproducts of foaming reaction escape through perforated die. Thus, volatiles are not trapped in pockets that can deform and weaken the molded part.

Deflectometric analysis of high volume injection molds for production of occupational eye wear.

PubMed

Speck, Alexis; Zelzer, Benedikt; Speich, Marco; Börret, Rainer; Langenbucher, Achim; Eppig, Timo

2013-12-01

Most of the protective eye wear devices currently on the market are manufactured on simple polycarbonate shields, produced by injection molding techniques. Despite high importance of optical quality, injection molds are rarely inspected for surface quality before or during the manufacturing process. Quality degradation is mainly monitored by optical testing of the molded parts. The purpose of this work was to validate a non-contact deflectometric measurement technique for surface and shape analysis of injection molds to facilitate deterministic surface quality control and to monitor minor conformity of the injection mold with the design data. The system is based on phase-measuring deflectometry with a operating measurement field of 80×80 mm(2) (±18° slope), a lateral resolution of 60μm and a local sensitivity of some nanometers. The calibration was tested with a calibration normal and a reference sphere. The results were crosschecked against a measurement of the same object with a tactile coordinate measuring machine. Eight injection molds for production of safety goggles with radii of +58mm (convex) and -60mm (concave) were measured in this study. The molds were separated into two groups (cavity 1 and 2 of the tool with different polishing techniques) and measured to test whether the measurement tool could extract differences. The analysis was performed on difference height between the measured surface and the spherical model. The device could derive the surface change due to polishing and discriminate between both polishing techniques, on the basis of the measured data. The concave nozzle sides of the first group (cavity 1) showed good shape conformity. In comparison, the nozzle sides of the second group (cavity 2) showed local deviations from design data up to 14.4μm. Local form variations of about 5μm occurred in the field of view. All convex ejector sides of both groups (cavity 1 and 2) showed rotational symmetric errors and the molds were measured in general flatter than design data. We applied a deflectometric system for measuring and evaluating specular reflective injection molding tools to optimize the production process of occupational eye wear. The surface quality could be inline monitored in the production processes for actual spectacle models. Copyright © 2013. Published by Elsevier GmbH.

Design of experiment for optimization of plasma-polymerized octafluorocyclobutane coating on very high aspect ratio silicon molds.

PubMed

Yeo, L P; Yan, Y H; Lam, Y C; Chan-Park, Mary B

2006-11-21

As-fabricated deep reactive ion etched (DRIE) silicon mold with very high aspect ratio (>10) feature patterns is unsuitable for poly(dimethylsiloxane) (PDMS) replication because of the strong interaction between the Si surface and the replica and the corrugated mold sidewalls. The silicon mold can be conveniently passivated via plasma polymerization of octafluorocyclobutane (C4F8), which is also employed in the DRIE process itself, to enable the mold to be used repeatedly. To optimize the passivation conditions, we have undertaken a Box-Behnken experimental design on the basis of three passivation process parameters (plasma power, C4F8 flow rate, and deposition time). The measured responses were fluorinated film thickness, demolding status/success, demolding force, and fluorine/carbon ratio on the fifth replica surface. The optimal passivation process conditions were predicted to be an input power of 195 W, a C4F8 flow rate of 57 sccm, and a deposition time of 364 s; these were verified experimentally to have high accuracy. Demolding success requires medium-deposited film thickness (66-91 nm), and the thickness of the deposited films correlated strongly with deposition time. At moderate to high ranges, increased plasma power or gas flow rate promoted polymerization over reactive etching of the film. It was also found that small quantities of the fluorinated surface were transferred from the Si mold to the PDMS at each replication, entailing progressive wear of the fluorinated layer.

Preparing silica aerogel monoliths via a rapid supercritical extraction method.

PubMed

Carroll, Mary K; Anderson, Ann M; Gorka, Caroline A

2014-02-28

A procedure for the fabrication of monolithic silica aerogels in eight hours or less via a rapid supercritical extraction process is described. The procedure requires 15-20 min of preparation time, during which a liquid precursor mixture is prepared and poured into wells of a metal mold that is placed between the platens of a hydraulic hot press, followed by several hours of processing within the hot press. The precursor solution consists of a 1.0:12.0:3.6:3.5 x 10(-3) molar ratio of tetramethylorthosilicate (TMOS):methanol:water:ammonia. In each well of the mold, a porous silica sol-gel matrix forms. As the temperature of the mold and its contents is increased, the pressure within the mold rises. After the temperature/pressure conditions surpass the supercritical point for the solvent within the pores of the matrix (in this case, a methanol/water mixture), the supercritical fluid is released, and monolithic aerogel remains within the wells of the mold. With the mold used in this procedure, cylindrical monoliths of 2.2 cm diameter and 1.9 cm height are produced. Aerogels formed by this rapid method have comparable properties (low bulk and skeletal density, high surface area, mesoporous morphology) to those prepared by other methods that involve either additional reaction steps or solvent extractions (lengthier processes that generate more chemical waste).The rapid supercritical extraction method can also be applied to the fabrication of aerogels based on other precursor recipes.

Preparing Silica Aerogel Monoliths via a Rapid Supercritical Extraction Method

PubMed Central

Gorka, Caroline A.

2014-01-01

A procedure for the fabrication of monolithic silica aerogels in eight hours or less via a rapid supercritical extraction process is described. The procedure requires 15-20 min of preparation time, during which a liquid precursor mixture is prepared and poured into wells of a metal mold that is placed between the platens of a hydraulic hot press, followed by several hours of processing within the hot press. The precursor solution consists of a 1.0:12.0:3.6:3.5 x 10-3 molar ratio of tetramethylorthosilicate (TMOS):methanol:water:ammonia. In each well of the mold, a porous silica sol-gel matrix forms. As the temperature of the mold and its contents is increased, the pressure within the mold rises. After the temperature/pressure conditions surpass the supercritical point for the solvent within the pores of the matrix (in this case, a methanol/water mixture), the supercritical fluid is released, and monolithic aerogel remains within the wells of the mold. With the mold used in this procedure, cylindrical monoliths of 2.2 cm diameter and 1.9 cm height are produced. Aerogels formed by this rapid method have comparable properties (low bulk and skeletal density, high surface area, mesoporous morphology) to those prepared by other methods that involve either additional reaction steps or solvent extractions (lengthier processes that generate more chemical waste).The rapid supercritical extraction method can also be applied to the fabrication of aerogels based on other precursor recipes. PMID:24637334

Ultrasonic Welding of Thermoplastic Composite Coupons for Mechanical Characterization of Welded Joints through Single Lap Shear Testing.

PubMed

Villegas, Irene F; Palardy, Genevieve

2016-02-11

This paper presents a novel straightforward method for ultrasonic welding of thermoplastic-composite coupons in optimum processing conditions. The ultrasonic welding process described in this paper is based on three main pillars. Firstly, flat energy directors are used for preferential heat generation at the joining interface during the welding process. A flat energy director is a neat thermoplastic resin film that is placed between the parts to be joined prior to the welding process and heats up preferentially owing to its lower compressive stiffness relative to the composite substrates. Consequently, flat energy directors provide a simple solution that does not require molding of resin protrusions on the surfaces of the composite substrates, as opposed to ultrasonic welding of unreinforced plastics. Secondly, the process data provided by the ultrasonic welder is used to rapidly define the optimum welding parameters for any thermoplastic composite material combination. Thirdly, displacement control is used in the welding process to ensure consistent quality of the welded joints. According to this method, thermoplastic-composite flat coupons are individually welded in a single lap configuration. Mechanical testing of the welded coupons allows determining the apparent lap shear strength of the joints, which is one of the properties most commonly used to quantify the strength of thermoplastic composite welded joints.

Ultrasonic Welding of Thermoplastic Composite Coupons for Mechanical Characterization of Welded Joints through Single Lap Shear Testing

PubMed Central

Villegas, Irene F.; Palardy, Genevieve

2016-01-01

This paper presents a novel straightforward method for ultrasonic welding of thermoplastic-composite coupons in optimum processing conditions. The ultrasonic welding process described in this paper is based on three main pillars. Firstly, flat energy directors are used for preferential heat generation at the joining interface during the welding process. A flat energy director is a neat thermoplastic resin film that is placed between the parts to be joined prior to the welding process and heats up preferentially owing to its lower compressive stiffness relative to the composite substrates. Consequently, flat energy directors provide a simple solution that does not require molding of resin protrusions on the surfaces of the composite substrates, as opposed to ultrasonic welding of unreinforced plastics. Secondly, the process data provided by the ultrasonic welder is used to rapidly define the optimum welding parameters for any thermoplastic composite material combination. Thirdly, displacement control is used in the welding process to ensure consistent quality of the welded joints. According to this method, thermoplastic-composite flat coupons are individually welded in a single lap configuration. Mechanical testing of the welded coupons allows determining the apparent lap shear strength of the joints, which is one of the properties most commonly used to quantify the strength of thermoplastic composite welded joints. PMID:26890931

Effect of Binder and Mold parameters on Collapsibility and Surface Finish of Gray Cast Iron No-bake Sand Molds

NASA Astrophysics Data System (ADS)

Srinivasulu Reddy, K.; Venkata Reddy, Vajrala; Mandava, Ravi Kumar

2017-08-01

Chemically bonded no-bake molds and cores have good mechanical properties and produce dimensionally accurate castings compared to green sand molds. Poor collapsibility property of CO2 hardened sodium silicate bonded sand mold and phenolic urethane no-bake (PUN) binder system, made the reclamation of the sands more important. In the present work fine silica sand is mixed with phenolic urethane no-bake binder and the sand sets in a very short time within few minutes. In this paper it is focused on optimizing the process parameters of PUN binder based sand castings for better collapsibility and surface finish of gray cast iron using Taguchi design. The findings were successfully verified through experiments.

THE DURABILITY OF LARGE-SCALE ADDITIVE MANUFACTURING COMPOSITE MOLDS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Post, Brian K; Love, Lonnie J; Duty, Chad

2016-01-01

Oak Ridge National Laboratory s Big Area Additive Manufacturing (BAAM) technology permits the rapid production of thermoplastic composite molds using a carbon fiber filled Acrylonitrile-Butadiene-Styrene (ABS) thermoplastic. Demonstration tools (i.e. 0.965 m X 0.559 m X 0.152 m) for composite part fabrication have been printed, coated, and finished with a traditional tooling gel. We present validation results demonstrating the stability of thermoplastic printed molds for room temperature Vacuum Assisted Resin Transfer Molding (VARTM) processes. Arkema s Elium thermoplastic resin was investigated with a variety of reinforcement materials. Experimental results include dimensional characterization of the tool surface using laser scanning techniquemore » following demolding of 10 parts. Thermoplastic composite molds offer rapid production compared to traditionally built thermoset molds in that near-net deposition allows direct digital production of the net geometry at production rate of 45 kg/hr.« less

Nonaqueous slip casting of high temperature ceramic superconductors using an investment casting technique

NASA Technical Reports Server (NTRS)

Hooker, Matthew W. (Inventor); Taylor, Theodore D. (Inventor); Wise, Stephanie A. (Inventor); Buckley, John D. (Inventor); Vasquez, Peter (Inventor); Buck, Gregory M. (Inventor); Hicks, Lana P. (Inventor)

1993-01-01

A process for slip casting ceramic articles that does not employ parting agents and affords the casting of complete, detailed, precision articles that do not possess parting lines is presented. This process is especially useful for high temperature superconductors and water-sensitive ceramics. A wax pattern for a shell mold is provided, and an aqueous mixture of a calcium sulfate-bonded investment material is applied as a coating to the wax pattern. The coated wax pattern is then dried, followed by curing to vaporize the wax pattern and leave a shell mold of the calcium sulfate-bonded investment material. The shell mold is cooled to room temperature, and a ceramic slip, created by dispersing a ceramic powder in an organic liquid, is poured therein. After a ceramic shell of desired thickness or a solid article has set up in the shell mold, excess ceramic slip is poured out. The shell mold is misted with water and peeled away from the ceramic article, after which the ceramic is fired to provide a complete, detailed, precision, high temperature superconductive ceramic article without parting lines. The casting technique may take place in the presence of a magnetic field to orient the ceramic powders during the casting process.

Experimental Studies of Heat-Transfer Behavior at a Casting/Water-Cooled-Mold Interface and Solution of the Heat-Transfer Coefficient

NASA Astrophysics Data System (ADS)

Zeng, Y. D.; Wang, F.

2018-02-01

In this paper, we propose an experimental model for forming an air gap at the casting/mold interface during the solidification process of the casting, with the size and formation time of the air gap able to be precisely and manually controlled. Based on this model, experiments of gravity casting were performed, and on the basis of the measured temperatures at different locations inside the casting and the mold, the inverse analysis method of heat transfer was applied to solve for the heat-transfer coefficient at the casting/mold interface during the solidification process. Furthermore, the impacts of the width and formation time of the air gap on the interface heat-transfer coefficient (IHTC) were analyzed. The results indicate that the experimental model succeeds in forming an air gap having a certain width at any moment during solidification of the casting, thus allowing us to conveniently and accurately study the impact of the air gap on IHTC using the model. In addition, the casting/mold IHTC is found to first rapidly decrease as the air gap forms and then slowly decrease as the solidification process continues. Moreover, as the width of the air gap and the formation time of the air gap increase, the IHTC decreases.

Liquid Crystalline Thermosets from Ester, Ester-Imide, and Ester-Amide Oligomers

NASA Technical Reports Server (NTRS)

Dingemans, Theodornus J. (Inventor); Weiser, Erik S. (Inventor); SaintClair, Terry L. (Inventor)

2005-01-01

Main chain thermotropic liquid crystal esters, ester-imides, and ester-amides were prepared from AA, BB, and AB type monomeric materials and were end-capped with phenylacetylene, phenylmaleimide, or nadimide reactive end-groups. The resulting reactive end-capped liquid crystal oligomers exhibit a variety of improved and preferred physical properties. The end-capped liquid crystal oligomers are thermotropic and have, preferably, molecular weights in the range of approximately 1000-15,OOO grams per mole. The end-capped liquid crystal oligomers have broad liquid crystalline melting ranges and exhibit high melt stability and very low melt viscosities at accessible temperatures. The end-capped liquid crystal oligomers are stable for up to an hour in the melt phase. These properties make the end-capped liquid crystal oligomers highly processable by a variety of melt process shape forming and blending techniques including film extrusion, fiber spinning, reactive injection molding (RIM), resin transfer molding (RTM), resin film injection (RFI), powder molding, pultrusion, injection molding, blow molding, plasma spraying and thermo-forming. Once processed and shaped, the end- capped liquid crystal oligomers were heated to further polymerize and form liquid crystalline thermosets (LCT). The fully cured products are rubbers above their glass transition temperatures. The resulting thermosets display many properties that are superior to their non-end-capped high molecular weight analogs.

Liquid crystalline thermosets from ester, ester-imide, and ester-amide oligomers

NASA Technical Reports Server (NTRS)

Dingemans, Theodorous J. (Inventor); Weiser, Erik S. (Inventor); St. Clair, Terry L. (Inventor)

2005-01-01

Main chain thermotropic liquid crystal esters, ester-imides, and ester-amides were prepared from AA, BB, and AB type monomeric materials and were end-capped with phenylacetylene, phenylmaleimide, or nadimide reactive end-groups. The resulting reactive end-capped liquid crystal oligomers exhibit a variety of improved and preferred physical properties. The end-capped liquid crystal oligomers are thermotropic and have, preferably, molecular weights in the range of approximately 1000-15,000 grams per mole. The end-capped liquid crystal oligomers have broad liquid crystalline melting ranges and exhibit high melt stability and very low melt viscosities at accessible temperatures. The end-capped liquid crystal oligomers are stable for up to an hour in the melt phase. These properties make the end-capped liquid crystal oligomers highly processable by a variety of melt process shape forming and blending techniques including film extrusion, fiber spinning, reactive injection molding (RIM), resin transfer molding (RTM), resin film injection (RFI), powder molding, pultrusion, injection molding, blow molding, plasma spraying and thermo-forming. Once processed and shaped, the end-capped liquid crystal oligomers were heated to further polymerize and form liquid crystalline thermosets (LCT). The fully cured products are rubbers above their glass transition temperatures. The resulting thermosets display many properties that are superior to their non-end-capped high molecular weight analogs.

Prosthetics & Orthotics Manufacturing Initiative (POMI)

DTIC Science & Technology

2012-12-21

the two materials. The rod was then put onto a lathe machine, allowing a thin sheet, with stripes of alternating materials, to be cut from the rod...tooling from. Mentis determined a method to use Aquacore, which involved machining blanks via CNC , followed by coating the mold to prevent resin...infusion into the mold. Mentis also attempted to use plaster combined with CNC machining, however, these molds did not survive the machining process

Optimization of process parameters in the RF-DC plasma N2-H2 for AISI420 molds and dies

NASA Astrophysics Data System (ADS)

Herdianto, Hengky; Djoko, D. J.; Santjojo, H.; Masruroh

2017-11-01

The RF-DC plasma N2-H2 was used to make precise AISI420 molds and dies have complex textured geometry. The quality of the molds and dies directly affect the quality of the produced parts. The excellent examples of molds were used for injection molding lenses and dies used for the precision forging of automotive drive train components. In this study, a temperature, DC bias, and duration as process parameters of the RF-DC plasma N2-H2 have been optimized for molds and dies fabrication. The mask-less micro-patterned method was utilized to draw the initial 2D micro patterns directly onto the AISI420 substrate surface. The unprinted substrate surfaces were selectively nitrided by the RF-DC plasma N2-H2 at 673 K for 5400 s by 70 Pa with hollow cathode device. Energy Dispersive X-ray was utilized to describe the nitrogen content distribution at the vicinity of the border between the unprinted surfaces. This exclusive nitrogen mapping proves that only the unprinted parts of the substrate have high content nitrogen solutes. XRD analysis was performed to investigate whether the iron nitrides were precipitated by RF-DC plasma N2-H2 in the AISI420.

Dimensional changes of acrylic resin denture bases: conventional versus injection-molding technique.

PubMed

Gharechahi, Jafar; Asadzadeh, Nafiseh; Shahabian, Foad; Gharechahi, Maryam

2014-07-01

Acrylic resin denture bases undergo dimensional changes during polymerization. Injection molding techniques are reported to reduce these changes and thereby improve physical properties of denture bases. The aim of this study was to compare dimensional changes of specimens processed by conventional and injection-molding techniques. SR-Ivocap Triplex Hot resin was used for conventional pressure-packed and SR-Ivocap High Impact was used for injection-molding techniques. After processing, all the specimens were stored in distilled water at room temperature until measured. For dimensional accuracy evaluation, measurements were recorded at 24-hour, 48-hour and 12-day intervals using a digital caliper with an accuracy of 0.01 mm. Statistical analysis was carried out by SPSS (SPSS Inc., Chicago, IL, USA) using t-test and repeated-measures ANOVA. Statistical significance was defined at P<0.05. After each water storage period, the acrylic specimens produced by injection exhibited less dimensional changes compared to those produced by the conventional technique. Curing shrinkage was compensated by water sorption with an increase in water storage time decreasing dimensional changes. Within the limitations of this study, dimensional changes of acrylic resin specimens were influenced by the molding technique used and SR-Ivocap injection procedure exhibited higher dimensional accuracy compared to conventional molding.

Advanced fabrication of Si nanowire FET structures by means of a parallel approach.

PubMed

Li, J; Pud, S; Mayer, D; Vitusevich, S

2014-07-11

In this paper we present fabricated Si nanowires (NWs) of different dimensions with enhanced electrical characteristics. The parallel fabrication process is based on nanoimprint lithography using high-quality molds, which facilitates the realization of 50 nm-wide NW field-effect transistors (FETs). The imprint molds were fabricated by using a wet chemical anisotropic etching process. The wet chemical etch results in well-defined vertical sidewalls with edge roughness (3σ) as small as 2 nm, which is about four times better compared with the roughness usually obtained for reactive-ion etching molds. The quality of the mold was studied using atomic force microscopy and scanning electron microscopy image data. The use of the high-quality mold leads to almost 100% yield during fabrication of Si NW FETs as well as to an exceptional quality of the surfaces of the devices produced. To characterize the Si NW FETs, we used noise spectroscopy as a powerful method for evaluating device performance and the reliability of structures with nanoscale dimensions. The Hooge parameter of fabricated FET structures exhibits an average value of 1.6 × 10(-3). This value reflects the high quality of Si NW FETs fabricated by means of a parallel approach that uses a nanoimprint mold and cost-efficient technology.

Dimensional Changes of Acrylic Resin Denture Bases: Conventional Versus Injection-Molding Technique

PubMed Central

Gharechahi, Jafar; Asadzadeh, Nafiseh; Shahabian, Foad; Gharechahi, Maryam

2014-01-01

Objective: Acrylic resin denture bases undergo dimensional changes during polymerization. Injection molding techniques are reported to reduce these changes and thereby improve physical properties of denture bases. The aim of this study was to compare dimensional changes of specimens processed by conventional and injection-molding techniques. Materials and Methods: SR-Ivocap Triplex Hot resin was used for conventional pressure-packed and SR-Ivocap High Impact was used for injection-molding techniques. After processing, all the specimens were stored in distilled water at room temperature until measured. For dimensional accuracy evaluation, measurements were recorded at 24-hour, 48-hour and 12-day intervals using a digital caliper with an accuracy of 0.01 mm. Statistical analysis was carried out by SPSS (SPSS Inc., Chicago, IL, USA) using t-test and repeated-measures ANOVA. Statistical significance was defined at P<0.05. Results: After each water storage period, the acrylic specimens produced by injection exhibited less dimensional changes compared to those produced by the conventional technique. Curing shrinkage was compensated by water sorption with an increase in water storage time decreasing dimensional changes. Conclusion: Within the limitations of this study, dimensional changes of acrylic resin specimens were influenced by the molding technique used and SR-Ivocap injection procedure exhibited higher dimensional accuracy compared to conventional molding. PMID:25584050

Lost Mold Rapid Infiltration Forming of Mesoscale Ceramics: Part 1, Fabrication

PubMed Central

Antolino, Nicholas E.; Hayes, Gregory; Kirkpatrick, Rebecca; Muhlstein, Christopher L.; Frecker, Mary I.; Mockensturm, Eric M.; Adair, James H.

2009-01-01

Free-standing mesoscale (340 μm × 30 μm × 20 μm) bend bars with an aspect ratio over 15:1 and an edge resolution as fine as a single grain diameter (∼400 nm) have been fabricated in large numbers on refractory ceramic substrates by combining a novel powder processing approach with photoresist molds and an innovative lost-mold thermal process. The colloid and interfacial chemistry of the nanoscale zirconia particulates has been modeled and used to prepare highly concentrated suspensions. Engineering solutions to challenges in mold fabrication and casting have yielded free-standing, crack-free parts. Molds are fabricated using high-aspect-ratio photoresist on ceramic substrates. Green parts are formed using a rapid infiltration method that exploits the shear thinning behavior of the highly concentrated ceramic suspension in combination with gelcasting. The mold is thermally decomposed and the parts are sintered in place on the ceramic substrate. Chemically aided attrition milling disperses and concentrates the as-received 3Y-TZP powder to produce a dense, fine-grained sintered microstructure. Initial three-point bend strength data are comparable to that of conventional zirconia; however, geometric irregularities (e.g., trapezoidal cross sections) are present in this first generation and are discussed with respect to the distribution of bend strength. PMID:19809595

DAMAGE MODELING OF INJECTION-MOLDED SHORT- AND LONG-FIBER THERMOPLASTICS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nguyen, Ba Nghiep; Kunc, Vlastimil; Bapanapalli, Satish K.

2009-10-30

This article applies the recent anisotropic rotary diffusion – reduced strain closure (ARD-RSC) model for predicting fiber orientation and a new damage model for injection-molded long-fiber thermoplastics (LFTs) to analyze progressive damage leading to total failure of injection-molded long-glass-fiber/polypropylene (PP) specimens. The ARD-RSC model was implemented in a research version of the Autodesk Moldflow Plastics Insight (MPI) processing code, and it has been used to simulate injection-molding of a long-glass-fiber/PP plaque. The damage model combines micromechanical modeling with a continuum damage mechanics description to predict the nonlinear behavior due to plasticity coupled with damage in LFTs. This model has beenmore » implemented in the ABAQUS finite element code via user-subroutines and has been used in the damage analyses of tensile specimens removed from the injection-molded long-glass-fiber/PP plaques. Experimental characterization and mechanical testing were performed to provide input data to support and validate both process modeling and damage analyses. The predictions are in agreement with the experimental results.« less

Fast and cheap fabrication of molding tools for polymer replication

NASA Astrophysics Data System (ADS)

Richter, Christiane; Kirschner, Nadine; Worgull, Matthias; Rapp, Bastian E.

2017-02-01

Polymer replication is a prerequisite for low-cost microstructure components for consumer and end user market. The production of cost-effective microstructure in polymers requires metal molding tools which are often fabricated by direct structuring methods like milling or laser machining both of which are time-consuming and cost-intensive. We present an alternative fabrication method based on replication processes which allows the cheap ( 50 €) and fast ( 12 h) replication of complex microstructures into metal. The process comprises three steps: 1. Generation of the microstructure in a photoresist via lithography. 2. Casting of the structure into a high-temperature silicone which serves as original mold for creation of the metal molding tool. 3. Melting of an eutectic alloy of Sn, Ag and Cu under light pressure directly inside of the silicone within an oven. After cooling to room temperature the metal molding tool can be used for polymer replication into conventional thermoplastic polymers. As a first example we structured polymethylmethacrylate (PMMA) foils with a thickness of 1 mm via hot embossing and feature sizes of 100 μm could be replicated with high fidelity.

Development of Maltodextrin-Based Immediate-Release Tablets Using an Integrated Twin-Screw Hot-Melt Extrusion and Injection-Molding Continuous Manufacturing Process.

PubMed

Puri, Vibha; Brancazio, Dave; Desai, Parind M; Jensen, Keith D; Chun, Jung-Hoon; Myerson, Allan S; Trout, Bernhardt L

2017-11-01

The combination of hot-melt extrusion and injection molding (HME-IM) is a promising process technology for continuous manufacturing of tablets. However, there has been limited research on its application to formulate crystalline drug-containing immediate-release tablets. Furthermore, studies that have applied the HME-IM process to molded tablets have used a noncontinuous 2-step approach. The present study develops maltodextrin (MDX)-based extrusion-molded immediate-release tablets for a crystalline drug (griseofulvin) using an integrated twin-screw HME-IM continuous process. At 10% w/w drug loading, MDX was selected as the tablet matrix former based on a preliminary screen. Furthermore, liquid and solid polyols were evaluated for melt processing of MDX and for impact on tablet performance. Smooth-surfaced tablets, comprising crystalline griseofulvin solid suspension in the amorphous MDX-xylitol matrix, were produced by a continuous process on a twin-screw extruder coupled to a horizontally opening IM machine. Real-time HME process profiles were used to develop automated HME-IM cycles. Formulation adjustments overcame process challenges and improved tablet strength. The developed MDX tablets exhibited adequate strength and a fast-dissolving matrix (85% drug release in 20 min), and maintained performance on accelerated stability conditions. Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Experimental investigation of defect criticality in FRP laminate composites

NASA Astrophysics Data System (ADS)

Joyce, Peter James

1999-11-01

This work examines the defect criticality of fiber reinforced polymer Composites. The objective is to determine the sensitivity of the finished composite to various process-induced defects. This work focuses on two different classes of process-induced defects; (1) fiber waviness in high performance carbon-fiber reinforced unidirectional composites and (2) void volume in low cost glass-fabric reinforced composites. The role of fiber waviness in the compressive response of unidirectional composites has been studied by a number of other investigators. Because of difficulties associated with producing real composites with varying levels of fiber waviness, most experimental studies of fiber waviness have evaluated composites with artificially induced fiber waviness. Furthermore, most experimental studies have been concentrated on the effects of out-of-plane fiber waviness. The objective of this work is to evaluate the effects of in-plane fiber waviness naturally occurring in autoclave consolidated thermoplastic laminates. The first phase of this project involved the development of a simple technique for measuring the resulting fiber waviness levels. An experimental investigation of the compression strength reduction in composites with in-plane fiber waviness followed. The experimental program included carbon-fiber reinforced thermoplastic composites manufactured from prepreg tape by hand layup, and carbon-fiber and glass-fiber reinforced composites manufactured from an experimental powder towpreg by filament winding and autoclave consolidation. The compression specimens exhibited kink band failure in the prepreg composite and varying amounts of longitudinal splitting and kink banding in the towpreg composites. The compression test results demonstrated the same trend as predicted by microbudding theory but the overall quantitative correlation was poor. The second thrust of this research evaluated void effects in resin transfer molded composites. Much of the existing literature in this area has focused on composites with unidirectional fiber reinforcement. In this program, the influence of void volume on the mechanical behavior of RTM composites with plain weave reinforcement was investigated. The experimental program demonstrated that the effects of void volume are negligible in terms of the fiber dominated properties. Interlaminar shear strength tests on the other hand demonstrated a linear dependence on void volume in the range tested.

Improved high temperature resistant matrix resins

NASA Technical Reports Server (NTRS)

Chang, G. E.; Powell, S. H.; Jones, R. J.

1983-01-01

The objective was to develop organic matrix resins suitable for service at temperatures up to 644 K (700 F) and at air pressures up to 0.4 MPa (60 psia) for time durations of a minimum of 100 hours. Matrix resins capable of withstanding these extreme oxidative environmental conditions would lead to increased use of polymer matrix composites in aircraft engines and provide significant weight and cost savings. Six linear condensation, aromatic/heterocyclic polymers containing fluorinated and/or diphenyl linkages were synthesized. The thermo-oxidative stability of the resins was determined at 644 K and compressed air pressures up to 0.4 MPa. Two formulations, both containing perfluoroisopropylidene linkages in the polymer backbone structure, exhibited potential for 644 K service to meet the program objectives. Two other formulations could not be fabricated into compression molded zero defect specimens.

Particle Image Velocimetry During Injection Molding

NASA Astrophysics Data System (ADS)

Bress, Thomas; Dowling, David

2012-11-01

Injection molding involves the unsteady non-isothermal flow of a non-Newtonian polymer melt. An optical-access mold has been used to perform particle image velocimetry (PIV) on molten polystyrene during injection molding. Velocimetry data of the mold-filling flow will be presented. Statistical assessments of the velocimetry data and scaled residuals of the continuity equation suggest that PIV can be conducted in molten plastics with an uncertainty of +/-2 percent. Simulations are often used to model polymer flow during injection molding to design molds and select processing parameters but it is difficult to determine the accuracy of these simulations due to a lack of in-mold velocimetry and melt-front progression data. Moldflow was used to simulate the filling of the optical-access mold, and these simulated results are compared to the appropriately-averaged time-varying velocity field measurements. Simulated results for melt-front progression are also compared with the experimentally observed flow fronts. The ratio of the experimentally measured average velocity magnitudes to the simulation magnitudes was found on average to be 0.99 with a standard deviation of 0.25, and the difference in velocity orientations was found to be 0.9 degree with a standard deviation of 3.2 degrees. formerly at the University of Michigan.

Factors influencing microinjection molding replication quality

NASA Astrophysics Data System (ADS)

Vera, Julie; Brulez, Anne-Catherine; Contraires, Elise; Larochette, Mathieu; Trannoy-Orban, Nathalie; Pignon, Maxime; Mauclair, Cyril; Valette, Stéphane; Benayoun, Stéphane

2018-01-01

In recent years, there has been increased interest in producing and providing high-precision plastic parts that can be manufactured by microinjection molding: gears, pumps, optical grating elements, and so on. For all of these applications, the replication quality is essential. This study has two goals: (1) fabrication of high-precision parts using the conventional injection molding machine; (2) identification of robust parameters that ensure production quality. Thus, different technological solutions have been used: cavity vacuuming and the use of a mold coated with DLC or CrN deposits. AFM and SEM analyses were carried out to characterize the replication profile. The replication quality was studied in terms of the process parameters, coated and uncoated molds and crystallinity of the polymer. Specific studies were processed to quantify the replicability of injection molded parts (ABS, PC and PP). Analysis of the Taguchi experimental designs permits prioritization of the impact of each parameter on the replication quality. A discussion taking into account these new parameters and the thermal and spreading properties on the coatings is proposed. It appeared that, in general, increasing the mold temperature improves the molten polymer fill in submicron features except for the steel insert (for which the presence of a vacuum is the most important factor). Moreover, the DLC coating was the best coating to increase the quality of the replication. This result could be explained by the lower thermal diffusivity of this coating. We noted that the viscosity of the polymers is not a primordial factor of the replication quality.

Analysis of form deviation in non-isothermal glass molding

NASA Astrophysics Data System (ADS)

Kreilkamp, H.; Grunwald, T.; Dambon, O.; Klocke, F.

2018-02-01

Especially in the market of sensors, LED lighting and medical technologies, there is a growing demand for precise yet low-cost glass optics. This demand poses a major challenge for glass manufacturers who are confronted with the challenge arising from the trend towards ever-higher levels of precision combined with immense pressure on market prices. Since current manufacturing technologies especially grinding and polishing as well as Precision Glass Molding (PGM) are not able to achieve the desired production costs, glass manufacturers are looking for alternative technologies. Non-isothermal Glass Molding (NGM) has been shown to have a big potential for low-cost mass manufacturing of complex glass optics. However, the biggest drawback of this technology at the moment is the limited accuracy of the manufactured glass optics. This research is addressing the specific challenges of non-isothermal glass molding with respect to form deviation of molded glass optics. Based on empirical models, the influencing factors on form deviation in particular form accuracy, waviness and surface roughness will be discussed. A comparison with traditional isothermal glass molding processes (PGM) will point out the specific challenges of non-isothermal process conditions. Furthermore, the underlying physical principle leading to the formation of form deviations will be analyzed in detail with the help of numerical simulation. In this way, this research contributes to a better understanding of form deviations in non-isothermal glass molding and is an important step towards new applications demanding precise yet low-cost glass optics.

Polyimides Based on Asymmetric Dianhydrides (II) (a-BPDA vs a-BTDA) for Resin Transfer Molding (RTM)

NASA Technical Reports Server (NTRS)

Chuang, Kathy C.; Criss, Jim M.; Mintz, Eric A.

2010-01-01

A new series of low-melt viscosity imide resins (10-20 poise at 280 C) were formulated from asymmetric 2,3,3',4' -benzophenone dianhydride (a-BTDA) and 4-phenylethynylphthalic endcaps, along with 3,4' -oxydianiline, 3,3' -methylenedianiline and 3,3'- diaminobenzophenone, using a solvent-free melt process. a-BTDA RTM resins exhibited higher glass transition temperatures (Tg's = 330-400 C) compared to those prepared by asymmetric 2,3,3',4' -biphenyl dianhydride, (a-BPDA, Tg's = 320-370 C). These low-melt viscosity imide resins were fabricated into polyimide/T650-35 carbon fiber composites by a RTM process. Composites properties of a-BTDA resins, such as open-hole compression and short-beam shear strength, are compared to those of composites made from a-BPDA based resin at room temperature, 288 C and 315 C. These novel, high temperature RTM imide resins exhibit outstanding properties beyond the performance of conventional RTM resins, such as epoxy and BMI resins which have use-temperatures around 177 C and 232 C for aerospace applications.

Effect of CaO on Hot Workability and Microstructure of Mg-9.5Zn-2Y Alloy

NASA Astrophysics Data System (ADS)

Kwak, Tae-yang; Kim, Daeguen; Yang, Jaehack; Yoon, Young-ok; Kim, Shae K.; Lim, Hyunkyu; Kim, Woo Jin

Mg-Zn-Y system alloys have been a great interest because Mg-Zn-Y alloys with I-phase exhibited high ductility at room and elevated temperatures. According to our preliminary experiments, the addition of CaO improved strength, but the process window became narrow. Therefore, the aim of current work was to find optimum extrusion conditions for CaO added Mg-Zn-Y alloys by processing maps. The 0.3 wt.% of CaO added Mg-9.5Zn-2Y (Mg95.6Zn3.8Y0.6) alloy was prepared by casting into steel mold and homogenizing. Hot compression test were performed in the Gleeble machine at temperature range of 250-400 °C with various strain rates. The alloys were extruded with a reduction ratio of 20:1. To analyze the microstructure and texture, optical micrograph, scanning electron microscope and electron backscattered diffraction were used. Moreover, we investigated the effects of metallic Ca addition in this alloy to compare with the addition of CaO.

[Biological monitoring in the molding of plastics and rubbers].

PubMed

Fustinoni, S; Campo, L; Cirla, A M; Cirla, P E; Cutugno, V; Lionetti, C; Martinotti, I; Mossini, E; Foà, V

2007-01-01

This survey was carried out in the molding of plastics and rubbers, in the "Professional Cancer Prevention Project" sponsored by the Lombardy region with the objective of developing and implementing protocols for evaluating exposure to carcinogens through the biological monitoring. The realities of molding the thermoplastic polymer ABS, rubber, and thermosetting plastics containing formaldehyde were examined. The carcinogenic substances identified in these processes were: 1,3-butadiene, acrylonitrile and styrene in molding ABS, polycyclic aromatic hydrocarbons (PAH) in molding rubber, and formaldehyde in molding the thermosetting plastics. Only for some of these substances biological indicators are available. The limited exposure to airborne chemicals in molding ABS and the intrinsic characteristics of biological indicators available for 1-3 butadiene have determined the non applicability of biological monitoring to this situation. The absence of a biological indicator of exposure to formaldehyde has made this situation not investigable. Exposure in the rubber molding was studied in 19 subjects applying the determination not metabolized PAH in urine. The levels of these indicators were similar to those measured in other groups of subjects without occupational exposure to PAH, confirming a low airborne contamination in this workplace.

The use of image analysis in evaluation of the fibers orientation in Wood-polymer composites (WPC)

NASA Astrophysics Data System (ADS)

Bednarz, Arkadiusz; Frącz, Wiesław; Janowski, Grzegorz

2016-12-01

In this paper a novel way of a digital analysis of fibers orientation with a five-step algorithmwas presented. In the study, a molded piece with a dumbbell shape prepared from wood-polymer composite was used. The injection molding process was examined in experimental and numerical way. Based on the developed mathematical algorithm, a significant compliance of fiber orientation in different areas of the molded piece was obtained. The main aim of thisworkwas fiber orientation analysis of wood-polymer composites. An additional goal of thiswork was the comparison of the results reached in numerical analysis with results obtained from an experiment. The results of this research were important for the scientific and also from the practical point of view. In future works the prepared algorithm could be used to reach optimal parameters of the injection molding process.

Porous electrode apparatus for electrodeposition of detailed metal structures or microelectronic interconnections

DOEpatents

Griffiths, Stewart K.; Nilson, Robert H.; Hruby, Jill M.

2002-01-01

An apparatus and procedure for performing microfabrication of detailed metal structures by electroforming metal deposits within small cavities. Two primary areas of application are: the LIGA process which manufactures complex three-dimensional metal parts and the damascene process used for electroplating line and via interconnections of microelectronic devices. A porous electrode held in contact or in close proximity with a plating substrate or mold top to ensure one-dimensional and uniform current flow into all mold cavities is used. Electrolyte is pumped over the exposed surface of the porous electrode to ensure uniform ion concentrations at this external surface. The porous electrode prevents electrolyte circulation within individual mold cavities, avoiding preferential enhancement of ion transport in cavities having favorable geometries. Both current flow and ion transport are one-dimensional and identical in all mold cavities, so all metal deposits grow at the same rate eliminating nonuniformities of the prior art.

Toward mass producible ordered bulk heterojunction organic photovoltaic devices.

PubMed

Kim, Taeyong; Yoon, Hyunsik; Song, Hyung-Jun; Haberkorn, Niko; Cho, Younghyun; Sung, Seung Hyun; Lee, Chang Hee; Char, Kookheon; Theato, Patrick

2012-12-13

A strategy to fabricate nanostructured poly(3-hexylthiophene) (P3HT) films for organic photovoltaic (OPV) cells by a direct transfer method from a reusable soft replica mold is presented. The flexible polyfluoropolyether (PFPE) replica mold allows low-pressure and low- temperature process condition for the successful transfer of nanostructured P3HT films onto PEDOT/PSS-coated ITO substrates. To reduce the fabrication cost of masters in large area, we employed well-ordered anodic aluminum oxide (AAO) as a template. Also, we provide a method to fabricate reversed nanostructures by exploiting the self-replication of replica molds. The concept of the transfer method in low temperature with a flexible and reusable replica mold obtained from an AAO template will be a firm foundation for a low-cost fabrication process of ordered OPVs. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Development of an impact- and solvent-resistant thermoplastic composite matrix, phase 4

NASA Technical Reports Server (NTRS)

Delano, C. B.

1987-01-01

Polyimides from BTDA with m-phenylenediamine and three aliphatic diamines were prepared in cresol and characterized. Characterization tests included compression strength and modulus, stressed solvent resistance, and melt-flow tests. Efforts to reduce the molecular weights of these polymers by either stoichiometric imbalance or phthalic anhydride end capping produced opacity in the polymer moldings when the stoichiometry was less than 99 percent. Use of 2,4-diaminotoluene in place of the m-phenylenediamine allowed clear polymer moldings to be obtained at all stoichiometries by end capping or stoichiometric imbalance. After melt-flow/molecular-weight studies, carbon fabric composites were prepared from three polyimide compositions containing BTDA, 2,4-diaminotoluene and two aliphatic diamines. Flexural strengths of two of the resins were in excess of 689 MPa (100 ksi) at both room temperature and 93 C. The polyimide from BTDA was selected for scale-up and neat resin characterization tests. The Tg of this polymer was 233 C.

Investigation of the shear thinning behavior of epoxy resins for utilization in vibration assisted liquid composite molding processes

NASA Astrophysics Data System (ADS)

Meier, R.; Kirdar, C.; Rudolph, N.; Zaremba, S.; Drechsler, K.

2014-05-01

Efficient production and consumption of energy are of greatest importance for contemporary industries and their products. This has led to an increasing application of lightweight materials in general and of Carbon Fiber Reinforced Plastics (CFRP) in particular. However, broader application of CFRP is often limited by high costs and manual labor production processes. These constraints are addressed by Liquid Composite Molding (LCM) processes. In LCM a dry fibrous preform is placed into a cavity and infiltrated mostly by thermoset resins; epoxy resins are wide spread in CFRP applications. One crucial parameter for a fast mold filling is the viscosity of the resin, which is affected by the applied shear rates as well as temperature and curing time. The work presented focuses on the characterization of the shear thinning behavior of epoxy resins. Furthermore, the correlation with the conditions in vibration assisted LCM processes, where additional shear rates are created during manufacture, is discussed. Higher shear rates result from high frequencies and/or high amplitudes of the vibration motions which are created by a vibration engine mounted on the mold. In rheological investigations the shear thinning behavior of a representative epoxy resin is studied by means of rotational and oscillatory experiments. Moreover, possible effects of shear rates on the chemical curing reaction are studied. Here, the time for gelation is measured for different levels of shear rates in a pre-shearing phase. Based on the rheological studies, the beneficial effect of vibration assistance in LCM processes with respect to mold filling can further be predicted and utilized.

High-Temperature Properties of Mold Flux Observed and Measured In Situ by Single/Double Hot-Thermocouple Technique

NASA Astrophysics Data System (ADS)

Wang, Wanlin; Lyu, Peisheng; Zhou, Lejun; Li, Huan; Zhang, Tongsheng

2018-05-01

Mold flux plays very important roles in the continuous casting process, and its high-temperature properties affect the quality of the final as-cast product greatly. Investigations on the melting, isothermal and nonisothermal crystallization, and phase evolution behaviors under a simulated temperature field for the mold flux system using the single/double hot-thermocouple technique (S/DHTT) were reviewed. Meanwhile, further in situ observations on the wetting behavior and heat transfer ability of the mold flux system were also carried out using the S/DHTT. The results summarized here provide a clear understanding of both the high-temperature properties of mold flux and the detailed application of advanced real-time visual high-temperature S/DHTT to this molten slag system.

Chemistry of rubber processing and disposal.

PubMed Central

Bebb, R L

1976-01-01

The major chemical changes during the processing of rubber occur with the breakdown in mastication and during vulcanization of the molded tire. There is little chemical change during the compounding, calendering, extrusion, and molding steps. Reclaiming is the process of converting scrap rubber into an unsaturated, processible product that can be vulcanized with sulfur. Pyrolysis of scrap rubber yields a complex mixture of liquids, gas, and residue in varying ratios dependent on the nature of the scrap and the conditions of pyrolysis. PMID:799964

Polymeric waveguide array with 45 degree slopes fabricated by bottom side tilted exposure

NASA Astrophysics Data System (ADS)

Lin, Xiaohui; Dou, Xinyuan; Wang, Alan X.; Chen, Ray T.

2011-01-01

This paper demonstrated a practical fabrication process of polymeric waveguide array (12 channels) with 50μm(W)×50μm(H)×23mm(L) dimension and mirror embedded 45° degree slopes for vertical coupling purpose. The entire process contained three main parts: a SU8 pre-mold with 45° slope, a PDMS mold and the final waveguide array device. The key step of fabricating the pre-mold included a bottom side tilted exposure of SU8 photo resist. By placing the sample upside down, tilting by 58.7° and immersing into DI water, the ultraviolet (UV) beam that shined vertically was directed to go through from the bottom of the glass substrate into top side SU8 resist with 45° angle to form the surface. This method was able to guarantee no-gap contact between the mask pattern and the photo resist when exposing. By comparing the process complexity and achieved structure of the top and bottom side exposure, the later was proved to be a promising method for making high quality tilted structure without any tailing effect. The reversed PDMS mold was then fabricated on the SU8 pre-mold. The PDMS mold was used to imprint the cladding layer of the waveguide array. After metal deposition, core filling and top cladding layer coating, the final polymeric waveguide array device was achieved. For performance evaluation, 850nm laser beam from VCSEL was modulated to 10Gbps signals and vertically coupled into the waveguide array. The eye diagrams revealed high Q factor when transmitting signals along these waveguide array.

Thermally stable laminating resins

NASA Technical Reports Server (NTRS)

Jones, R. J.; Vaughan, R. W.; Burns, E. A.

1972-01-01

Improved thermally stable laminating resins were developed based on the addition-type pyrolytic polymerization. Detailed monomer and polymer synthesis and characterization studies identified formulations which facilitate press molding processing and autoclave fabrication of glass and graphite fiber reinforced composites. A specific resin formulation, termed P10P was utilized to prepare a Courtaulds HMS reinforced simulated airfoil demonstration part by an autoclave molding process.

Resin transfer molding for advanced composite primary aircraft structures

NASA Technical Reports Server (NTRS)

Markus, Alan; Palmer, Ray

1991-01-01

Resin Transfer Molding (RTM) has been identified by Douglas Aircraft Company (DAC) and industry to be one of the promising processes being developed today which can break the cost barrier of implementing composite primary structures into a commercial aircraft production environment. The RTM process developments and scale-up plans Douglas Aircrart will be conducting under the NASA ACT contract are discussed.