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Sample records for injection molding

  1. INJECTION-MOLDING APPARATUS

    DOEpatents

    Lobell, G.M.

    1958-02-11

    This patent is drawn to an injection molding apparatus for producing a tube closed at one end wherein the normally unsupported end of the core located in the cavity during the injection of the molten material to fill the space between the core and cavity wall, which supporting means is automatically removed from operation during the forming of the closed end of the tube. This support means is a plug extending through the end of the core into a recess in the bottom of the cavity where the closed end of the tube is to be formed. The plug is spring pressed into said recess and is forced out of the recess by a slidable bushing at the top of the cavity which is moved against the force of the spring by the molten material when it fills the uppormost open end portion of the cavity, thereby permitting the closed end of the tube to be formed.

  2. Advances in Aluminum Mold Block for Plastic Injection Molding Operations

    NASA Astrophysics Data System (ADS)

    Kim, Jinsoo; Smierciak, Ron; Shin, Yong Seung; Cooper, Leighton

    Mold performance with high strength aluminum alloy QC-10® in injection molding was investigated and compared with NAK 80 steel mold. Two different shapes of molds were tooled and tested. Interfacial heat fluxes between cooling mold and solidifying polymer melt were measured using the IHCP (Inverse Heat Conduction Method) technique during the injection molding cycles. The influence of thermo-physical properties of mold materials and polymer resins on molding cycle time and internal residual stress were also investigated by injection molding control optimization and birefringence analyzer. Evaluation of the thermal energy absorbed and uniform heat extraction during injection molding revealed that aluminum mold QC-10® resulted in significant cycle time reduction and produced the part with less distortion. In addition to the benefit of reduced tooling time, it was proven that aluminum mold is a promising mold material for increasing the productivity in plastic injection molding operations.

  3. 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...

  4. Injection molding of engineering plastics

    NASA Astrophysics Data System (ADS)

    Kalyon, Dilhan M.

    1991-03-01

    This final report summarizes the findings of a study in injection molding of engineering plastics. Two engineering plastic resins, i.e., unmodified grades of a polyetherimide and a poly (2,6-dimethyl-1,4-phenylene ether) were thoroughly characterized. The characterization included rheology, thermal properties and P-V-T behavior. The data were employed to predict various microstructural distributions including density, residual stress and birefringence distributions in compression and injection molded specimens of these two engineering plastics. The detailed microstructural distributions were also studied experimentally upon processing the two engineering plastics, employing instrumented machines and industrial practices. The experimental findings were elucidated under the light of the numerical simulation results. Overall, this study should furnish a first order understanding of the microstructure development in articles injection molded from amorphous engineering plastic resins.

  5. Injection Molding of Plastics from Agricultural Materials

    SciTech Connect

    Bhattacharya, M.; Ruan, R.

    2001-02-22

    The objective of this research was to conduct a systematic study to relate injection molding parameters to properties of blends of starch and synthetic polymer. From this study, we wished to develop a thorough understanding of the injection molding process and gain significant insight into designing molds and aiding in developing products cheaply and efficiently.

  6. 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.

  7. 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.

  8. Porous media heat transfer for injection molding

    DOEpatents

    Beer, Neil Reginald

    2016-05-31

    The cooling of injection molded plastic is targeted. Coolant flows into a porous medium disposed within an injection molding component via a porous medium inlet. The porous medium is thermally coupled to a mold cavity configured to receive injected liquid plastic. The porous medium beneficially allows for an increased rate of heat transfer from the injected liquid plastic to the coolant and provides additional structural support over a hollow cooling well. When the temperature of the injected liquid plastic falls below a solidifying temperature threshold, the molded component is ejected and collected.

  9. Planning an Injection Mold Design Training Program.

    ERIC Educational Resources Information Center

    Allyn, Edward P.

    With the increased use of plastics worldwide the shortage of trained personnel in moldmaking and design for plastic injection molds is becoming critical. Local schools and community colleges should provide courses in mold design and mold making, since most workers presently learn while working under experienced designers on the job. Following this…

  10. A comparison of molding procedures - Contact, injection and vacuum injection

    NASA Astrophysics Data System (ADS)

    Cathiard, G.

    1980-06-01

    The technical and economic aspects of the contact, injection and vacuum injection molding of reinforced plastic components are compared for the example of a tractor roof with a gel-coated surface. Consideration is given to the possibility of reinforcement, number of smooth faces, condition of the gel-coated surface, reliability, and labor and workplace requirements of the three processes, and advantages of molding between the mold and a countermold in smooth faces, reliability, labor requirements, working surface and industrial hygiene are pointed out. The times and labor requirements of each step in the molding cycles are examined, and material requirements and yields, investment costs, amortization and product cost prices of the processes are compared. It is concluded that, for the specific component examined, the processes of vacuum injection and injection molding appear very interesting, with injection molding processes resulting in lower cost prices than contact molding for any production volume.

  11. Injection molded optical backplane for broadcast architecture

    NASA Astrophysics Data System (ADS)

    Rosenberg, Paul; Mathai, Sagi; Sorin, Wayne V.; McLaren, Moray; Straznicky, Joseph; Panotopoulos, Georgios; Warren, David; Morris, Terry; Tan, Michael R. T.

    2012-01-01

    A low cost, blind mate, injection molded optical backplane is presented. The optical backplane is comprised of 12 channel optical broadcast buses, operating at 10Gbps/channel with six blindmate optical output ports spaced 1U apart.

  12. Rapid control of mold temperature during injection molding process

    SciTech Connect

    Liparoti, Sara; Titomanlio, Giuseppe; Hunag, Tsang Min; Cakmak, Mukerrem; Sorrentino, Andrea

    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 the 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.

  13. Metal Injection Molding of Tungsten Heavy Alloys: SBIR Phase 1

    DTIC Science & Technology

    1991-10-01

    Huntington Beach, CA). Task 7: Injection Molding Injection Molding was performed in a Arburg (Model 305-211-700) with test specimens provided for both solid... Arburg Injection Molding machine (Model 305-211-700). The molding conditions were: Temperature: Nozzle - 177°C (350°F) Front - 177 0 C (350°F) Middle

  14. 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.

  15. The research of UV curing injection molding

    NASA Astrophysics Data System (ADS)

    Xie, Pengcheng; Chang, Le; Song, Le; Cai, Tianze; Ding, Yumei; Yang, Weimin

    2015-05-01

    The micro-injection molding technology and the UV (ultraviolet) curing technique are combined to bring about a new plastic forming method, UV curing injection molding. The mean weight of micro-product is an important process characteristic for UV curing injection molding as well as the surface quality of micro-features is another important process characteristic for this new plastic forming method. This research investigates three effects of processing factors on the mass-change rate of micro-product and the surface quality of micro-features. In every particular, the following two factors are considered: UV material system temperature and the packing pressure. The study revealed that as usual, the micro-products gain weight with the imported increasing UV material system temperature and the improved packing pressure. Meanwhile, the increasing packing pressure also improves the surface quality, yet, warming the UV system temperature up has no effect on the quality of the product.

  16. Surface Replication of Molded Products with Microneedle Features in Injection Molding

    NASA Astrophysics Data System (ADS)

    Uchiumi, Kazuyasu; Takayama, Tetsuo; Ito, Hiroshi; Inou, Akinori

    Micro-molding of microneedle features was conducted using several injection-molding techniques. Injection compression molding and injection molding were performed with supercritical carbon dioxide fluid and with or without vacuum processing inside the mold cavity. Effects of process parameters on processability and surface replication of the molded parts were evaluated. The height replication ratio for microneedles was improved using injection compression molding. At a shorter compression stroke, the needle height was improved, and the influence of compression delay time was also small. Moreover, the effects of vacuum processing inside the mold cavity under the filling process were slight. The height replication ratio for microneedles showed the highest values using injection molding using supercritical carbon dioxide fluid with vacuum inside the mold cavity.

  17. 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

  18. Photorefractive polymer composites fabricated by injection molding

    NASA Astrophysics Data System (ADS)

    Herlocker, J. A.; Fuentes-Hernandez, C.; Wang, J. F.; Peyghambarian, N.; Kippelen, B.; Zhang, Q.; Marder, S. R.

    2002-02-01

    We report on the fabrication of bulk samples of photorefractive polymers using the injection molding technique. The photorefractive properties of these materials are evaluated by four-wave mixing and two-beam coupling experiments. Samples with good optical quality, high diffraction efficiency, and net optical gain are obtained.

  19. An automatic quality system for injection molding

    NASA Astrophysics Data System (ADS)

    Koikkalainen, Pasi; Haranen, Michael; Lensu, Anssi; Sippola, Risto

    2007-09-01

    This paper describes a fully automatic quality system for injection molding. The proposed system includes an on-line measurement platform with a digital camera, a methodology for adaptive design of experiments (DOE), statistical modeling, process monitoring, and a closed loop process control. The system has been tested in the manufacturing of plastic parts for mobile phones.

  20. Injection molding and debinding of micro gears fabricated by micro powder injection molding

    NASA Astrophysics Data System (ADS)

    Ni, Xin-lei; Yin, Hai-qing; Liu, Lin; Yi, Shan-jie; Qu, Xuan-hui

    2013-01-01

    Micro powder injection molding (μPIM) was investigated for possible mass production of micro-components at relatively low cost. However, scaling down to such a level produces challenges in injection molding and debinding. Micro gears were fabricated by μPIM from in-house feedstock. The effect of injection speed and injection pressure on the replication of the micro gear cavity was investigated. Solvent debinding and thermal debinding processes were discussed. The results show that micro gears can be successfully fabricated under the injection pressure of 70 MPa and the 60% injection speed. Either too low or too high injection speed can cause incomplete filling of micro gears. The same is the case with too low injection pressure. Too high injection pressure can bring cracks. Solvent debinding of micro gears was performed in a mixture of petroleum ether and ethanol. Subsequently, micro gears were successfully debound by a multistep heating schedule.

  1. 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 (...

  2. The use of IR thermography to show the mold and part temperature evolution in injection molding

    NASA Astrophysics Data System (ADS)

    Bula, Karol; Różański, Leszek; Marciniak-Podsadna, Lidia; Wróbel, Dawid

    2016-12-01

    This study concerns the application of infrared camera for injection molding analysis by measuring temperatures of both injection molded parts and injection mold cavities in a function of injection cycles. The mold with two cavities, differing in thickness (1 and 3 mm), and a cold direct runner was used. Isotactic polypropylene homopolymer was utilized to produce parts. Mold temperature was set at 22°C and controlled by a water chiller. Five measuring points were determined: SP1, SP2 (placed in the 3 mm cavity), SP3, SP4 (located in the 1 mm cavity) and SP5 around an injection molding gate. Our investigations showed that the highest temperature is localized around SP2 point and the lowest at SP4. Also, it was proved that even after 62 injection molding cycles, temperatures of cavities were not stable, revealing their further increase with each cycle.

  3. Effect of process parameters on cavity pressure in injection molding

    NASA Astrophysics Data System (ADS)

    Wang, Quan; Zhen, Mengxiang; Wu, Zhenghuan; Cai, Yujun

    2017-03-01

    In this study, an experimental work is performed on the effect of injection molding parameters on the polymer pressure inside the mold cavity. Different process parameters of the injection molding are considered during the experimental work (packing pressure, packing time, injection pressure, mold temperature, and melt temperature). A set analyses are carried out by combining the process parameters based on the L16(45)Taguchi orthogonal design. The cavity pressure is measured with time by using Kistler pressure sensor at different injection molding cycles. The results show the packing pressure is significant factor of affecting the maximum of diverse spline cavity pressure. The results obtained specify well the developing of the cavity pressure inside the mold cavity during the injection molding cycles.

  4. Metal Injection Molding for Superalloy Jet Engine Components

    DTIC Science & Technology

    2006-05-01

    RTO-MP-AVT-139 9 - 1 UNCLASSIFIED/UNLIMITED UNCLASSIFIED/UNLIMITED Metal Injection Molding for Superalloy Jet Engine...muc.mtu.de METAL INJECTION MOLDING FOR SUPERALLOY JET ENGINE COMPONENTS The Metal Injection Molding [MIM] process is a combination of powder...firearms and medical. MTU Aero Engines GmbH advanced the MIM process using high temperature superalloys powders. Optimized thermal processes and

  5. Thermal monitoring of the thermoplastic injection molding process with FBGs

    NASA Astrophysics Data System (ADS)

    Alberto, Nélia J.; Nogueira, Rogério N.; Neto, Victor F.

    2014-08-01

    Injection molding is an important polymer processing method for manufacturing plastic components. In this work, the thermal monitoring of the thermoplastic injection molding is presented, since temperature is a critical parameter that influences the process features. A set of fiber Bragg gratings were multiplexed, aiming a two dimensional monitoring of the mold. The results allowed to identify the different stages of the thermoplastic molding cycle. Additionally, the data provide information about the heat transfer phenomena, an important issue for the thermoplastic injection sector, and thus for an endless number of applications that employ this type of materials.

  6. 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...

  7. 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.

  8. Fast prototyping of injection molded polymer microfluidic chips

    NASA Astrophysics Data System (ADS)

    Steen Hansen, Thomas; Selmeczi, David; Larsen, Niels B.

    2010-01-01

    We present fast prototyping of injection molding tools by the definition of microfluidic structures in a light-curable epoxy (SU-8) directly on planar nickel mold inserts. Optimized prototype mold structures could withstand injection molding of more than 300 replicas in cyclic olefin copolymer (COC) without any signs of failure or release. The key parameters to avoid mold failure are maximum adhesion strength of the epoxy to the nickel insert and minimum interfacial energy of the epoxy pattern to the molded polymer. Optimal molding of microstructures with vertical sidewalls was found for nickel inserts pre-coated by silicon oxide before applying the structured epoxy, followed by coating of the epoxy by a fluorocarbon layer prior to injection molding. Further improvements in the mold stability were observed after homogeneous coating of the patterned epoxy by a second reflowed layer of epoxy, likely due to the resulting reduction in sidewall steepness. We employed the latter method for injection molding bondable polymer microfluidic chips with integrated conducting polymer electrode arrays that permitted the culture and on-chip analysis of cell spreading by impedance spectroscopy.

  9. Injection-molded nanocomposites and materials based on wheat gluten.

    PubMed

    Cho, S-W; Gällstedt, M; Johansson, E; Hedenqvist, M S

    2011-01-01

    This is, to our knowledge, the first study of the injection molding of materials where wheat gluten (WG) is the main component. In addition to a plasticizer (glycerol), 5 wt.% natural montmorillonite clay was added. X-ray indicated intercalated clay and transmission electron microscopy indicated locally good clay platelet dispersion. Prior to feeding into the injection molder, the material was first compression molded into plates and pelletized. The filling of the circular mold via the central gate was characterized by a divergent flow yielding, in general, a stronger and stiffer material in the circumferential direction. It was observed that 20-30 wt.% glycerol yielded the best combination of processability and mechanical properties. The clay yielded improved processability, plate homogeneity and tensile stiffness. IR spectroscopy and protein solubility indicated that the injection molding process yielded a highly aggregated structure. The overall conclusion was that injection molding is a very promising method for producing WG objects.

  10. Analysis of optical properties in injection-molded and compression-molded optical lenses.

    PubMed

    Wang, Chung Yen; Wang, Pei Jen

    2014-04-10

    Numerical mold-flow simulations and experimental measurements for injection-molded lenses have been investigated in form accuracy on a two-cavity mold with various process conditions. First, form profiles of the molded lenses have been measured together with the corresponding simulated mold-temperature distribution and displacement distribution of the lens in the z direction. A flow-through type layout of cooling channels has been devised for balance of mold-temperature distribution in mold cavities with various parametric distances for assessments in uniformity of temperature distribution. Finally, a compression-molding process is proposed for the post-process of birefringence relaxation as well as adequate form accuracy of lenses. In conclusion, optimization of process parameters to achieve good form accuracy in a multicavity mold with symmetric geometry but nonuniform cooling conditions is difficult. A good design of cooling channels plus optimized process conditions could provide uniform mold-temperature distribution so that molded lenses of good quality would be possible. Then, the profile deviation of lenses could be further compensated by profile geometry corrections. In conclusion, the post-compression-molding process could make birefringence-free plastic lenses with good form accuracy.

  11. Effects of mold geometry on fiber orientation of powder injection molded metal matrix composites

    SciTech Connect

    Ahmad, Faiz Aslam, Muhammad Altaf, Khurram Shirazi, Irfan

    2015-07-22

    Fiber orientations in metal matrix composites have significant effect on improving tensile properties. Control of fiber orientations in metal injection molded metal composites is a difficult task. In this study, two mold cavities of dimensions 6x6x90 mm and 10x20x180 mm were used for comparison of fiber orientation in injection molded metal composites test parts. In both mold cavities, convergent and divergent flows were developed by modifying the sprue dimensions. Scanning electron microscope (SEM) was used to examine the fiber orientations within the test samples. The results showed highly aligned fiber in injection molded test bars developed from the convergent melt flow. Random orientation of fibers was noted in the composites test bars produced from divergent melt flow.

  12. Injection molding simulation with variothermal mold temperature control of highly filled polyphenylene sulfide

    NASA Astrophysics Data System (ADS)

    Birkholz, A.; Tschiersky, M.; Wortberg, J.

    2015-05-01

    For the installation of a fuel cell stack to convert chemical energy into electricity it is common to apply bipolar plates to separate and distribute reaction gases and cooling agents. For reducing manufacturing costs of bipolar plates a fully automated injection molding process is examined. The high performance thermoplastic matrix material, polyphenylene sulfide (PPS), defies against the chemical setting and the operation temperature up to 200 °C. To adjust also high electrical and thermal conductivity, PPS is highly filled with various carbon fillers up to an amount of 65 percentage by volume. In the first step two different structural plates (one-sided) with three different gate heights and molds are designed according to the characteristics of a bipolar plate. To cope with the approach that this plate should be producible on standard injection molding machines with variothermal mold temperature control, injection molding simulation is used. Additionally, the simulation should allow to formulate a quality prediction model, which is transferrable to bipolar plates. Obviously, the basis for a precise simulation output is an accurate description of the material properties and behavior of the highly filled compound. This, the design of the structural plate and mold and the optimization via simulation is presented, as well. The influence of the injection molding process parameters, e.g. injection time, cycle times, packing pressure, mold temperature, and melt temperature on the form filling have been simulated to determine optimal process conditions. With the aid of the simulation and the variothermal mold temperature control it was possible to reduce the required melt temperature below the decomposition temperature of PPS. Thereby, hazardous decomposition products as hydrogen sulfide are obviated. Thus, the health of the processor, the longevity of the injection molding machine as well as the material and product properties can be protected.

  13. Design and development of injection molded Fresnel lenses for point-focus photovoltaic systems

    SciTech Connect

    Grendol, C.L.

    1987-05-01

    A summary of work performed on a method of injection molding an 80% efficient point-focus Fresnel lens is presented. A current optical design for compression molded lenses yields a 68.5% efficiency when translated directly to injection molding. An optical design optimized for injection molding, with a mold and process developed for high efficiency Fresnel lenses, yields an 82% efficiency.

  14. Smart plastic functionalization by nanoimprint and injection molding

    NASA Astrophysics Data System (ADS)

    Zalkovskij, Maksim; Thamdrup, Lasse H.; Smistrup, Kristian; Andén, Thomas; Johansson, Alicia C.; Mikkelsen, Niels Jørgen; Madsen, Morten Hannibal; Garnæs, Jørgen; Kristiansen, Tommy Tungelund; Diemer, Mads; Døssing, Michael; Minzari, Daniel; Tang, Peter Torben; Kristensen, Anders; Taboryski, Rafael; Essendrop, Søren; Nielsen, Theodor; Bilenberg, Brian

    2015-03-01

    In this paper, we present a route for making smart functionalized plastic parts by injection molding with sub-micrometer surface structures. The method is based on combining planar processes well known and established within silicon micro and sub-micro fabrication with proven high resolution and high fidelity with truly freeform injection molding inserts. The link between the planar processes and the freeform shaped injection molding inserts is enabled by the use of nanoimprint with flexible molds for the pattern definition combined with unidirectional sputter etching for transferring the pattern. With this approach, we demonstrate the transfer of down to 140 nm wide holes on large areas with good structure fidelity on an injection molding steel insert. The durability of the sub-micrometer structures on the inserts have been investigated by running two production series of 102,000 and 73,000 injection molded parts, respectively, on two different inserts and inspecting the inserts before and after the production series and the molded parts during the production series.

  15. 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.

  16. Wear resistance of injection-molded thermoplastic denture base resins.

    PubMed

    Hamanaka, Ippei; Iwamoto, Misa; Lassila, Lippo V J; Vallittu, Pekka K; Takahashi, Yutaka

    2016-12-01

    Objective This study investigated the wear resistance of injection-molded thermoplastic denture base resins using nanoindentation instrument. Materials and methods Six injection-molded thermoplastic denture base resins (two polyamides, two polyesters, one polycarbonate, one polymethylmethacrylate [PMMA]) and a PMMA conventional heat-polymerized denture-based polymer control were tested. Elastic modulus, hardness, wear depth, and roughness were calculated using a nanoindentation instrument. Results Elastic modulus and hardness of the injection-molded thermoplastic denture base resins were significantly lower than those of the PMMA conventional heat-polymerized denture-based polymer. Wear depth of polycarbonate and PMMA conventional heat-polymerized denture-based polymer were significantly higher than that of other injection-molded thermoplastic denture base resins. The roughness of injection-molded thermoplastic denture base resins was significantly more than that of PMMA conventional heat-polymerized denture-based polymer after testing. Conclusions Wear resistance of injection-molded thermoplastic denture base was low compared to PMMA conventional heat-polymerized denture-based polymers.

  17. Wear resistance of injection-molded thermoplastic denture base resins

    PubMed Central

    Hamanaka, Ippei; Iwamoto, Misa; Lassila, Lippo V. J.; Vallittu, Pekka K.; Takahashi, Yutaka

    2016-01-01

    Abstract Objective This study investigated the wear resistance of injection-molded thermoplastic denture base resins using nanoindentation instrument. Materials and methods Six injection-molded thermoplastic denture base resins (two polyamides, two polyesters, one polycarbonate, one polymethylmethacrylate [PMMA]) and a PMMA conventional heat-polymerized denture-based polymer control were tested. Elastic modulus, hardness, wear depth, and roughness were calculated using a nanoindentation instrument. Results Elastic modulus and hardness of the injection-molded thermoplastic denture base resins were significantly lower than those of the PMMA conventional heat-polymerized denture-based polymer. Wear depth of polycarbonate and PMMA conventional heat-polymerized denture-based polymer were significantly higher than that of other injection-molded thermoplastic denture base resins. The roughness of injection-molded thermoplastic denture base resins was significantly more than that of PMMA conventional heat-polymerized denture-based polymer after testing. Conclusions Wear resistance of injection-molded thermoplastic denture base was low compared to PMMA conventional heat-polymerized denture-based polymers. PMID:28642909

  18. Residual orientation in micro-injection molded parts

    SciTech Connect

    Healy, John; Edward, Graham H.; Knott, Robert B.

    2008-06-30

    The residual orientation following micro-injection molding of small rectangular plates with linear polyethylene has been examined using small-angle neutron scattering, and small- and wide-angle X-ray scattering. The effect of changing the molding conditions has been examined, and the residual chain orientation has been compared to the residual orientation of the crystallites as a function of position in the sample. This study has found that, for micromoldings, the orientation of the crystallites decreases with increasing injection speed and increasing mold thickness. The combined data suggest that the majority of the orientation present comes from oriented crystal growth rather than residual chain orientation.

  19. Rapid control of mold temperature during injection molding process: Effect of packing pressure

    NASA Astrophysics Data System (ADS)

    Liparoti, Sara; Sorrentino, Andrea; Titomanlio, Giuseppe

    2015-12-01

    A thorough analysis of the effect of operative conditions of injection molding process on the morphology distribution inside the obtained molded is performed, with particular reference to semi- crystalline polymers. In particular, fully characterized injection molding tests are presented using an isotactic polypropylene, previously carefully characterized as far as most of properties of interest. The effects of mold temperature and packing conditions are analyzed. The mold temperature was controlled by a thin heating device, composed by polyimide as insulating layer and polyimide loaded carbon black as electrical conductive layer, that is able to increase temperature on mold surface in few seconds (70°C/s) by joule effect and cool down soon after. The shear layer thickness in the molded is reduced in the samples produced at high mold temperatures, that means high electrical power and long heating time, and this reduction is more significant at lower packing pressures, indeed, at 360bar as packing pressure and 20s as heating time the shear layer disappear. The resulting morphology was analyzed by optical microscope.

  20. 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.

  1. 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

  2. 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.

  3. Injection molded polymer optics in the 21st Century

    NASA Astrophysics Data System (ADS)

    Beich, William S.

    2005-08-01

    Precision polymer optics, manufactured by injection molding techniques, has been a key enabling technology for several decades now. The technology, which can be thought of as a subset of the wider field of precision optics manufacturing, was pioneered in the United States by companies such as Eastman Kodak, US Precision Lens, and Polaroid. In addition to suppliers in the U.S. there are several companies worldwide that design and manufacture precision polymer optics, for example Philips High Tech Plastics in Europe and Fujinon in Japan. Designers who are considering using polymer optics need a fundamental understanding of exactly how the optics are created. This paper will survey the technology and processes that are employed in the successful implementation of a polymer optic solution from a manufacturer's perspective. Special emphasis will be paid to the unique relationship between the molds and the optics that they produce. We will discuss the key elements of production: molding resins, molds and molding equipment, and metrology. Finally we will offer a case study to illustrate just how the optics designer carries a design concept through to production. The underlying theme throughout the discussion of polymer optics is the need for the design team to work closely with an experienced polymer optics manufacturer with a solid track record of success in molded optics. As will be seen shortly, the complex interaction between thermoplastics, molds, and molding machines dictates the need for working closely with a supplier who has the critical knowledge needed to manage all aspects of the program.

  4. The Influence of Molding Conditions on Solidification Growth during Injection Molding

    NASA Astrophysics Data System (ADS)

    Seto, Masahiro; Wada, Takuya; Satoh, Kazuhito; Okada, Yuji; Yamabe, Masashi

    The CAE method for the injection molding process is now used in the plastic industry for the purpose of predicting warp problems. But the accuracy of this is not good enough for the mold designer. We have proposed a theoretical method to predict anisotropic property distribution for the thermal expansion coefficient in the thickness direction. It was found that there is a good relation between the thermal expansion and the molecular orientations, and also between the thermal expansion coefficient and the energy of shear rate. It is important to know the growing process of the solidified layer during the injection molding, to obtain the accurate flow mode as key information for CAE technology. In this paper, visualization experiments were conducted on the effects of molding conditions on solidified layer growth. The results made the following points clear. 1) The effects of resin temperature and mold temperature on solidified layer growth are low. 2) Solidified layer growth changes depending on resin flow velocity in cavity during the injection molding. 3) Growth rate of solidified layer is affected by shear heat resulting from distribution of resin flow velocity. Therefore it is important to predict the shear heat for predicting the growth rate of the solidified layer.

  5. Morphology Evolution during Injection Molding: effect of packing pressure

    NASA Astrophysics Data System (ADS)

    Pantani, R.; Coccorullo, I.; Speranza, V.; Titomanlio, G.

    2007-04-01

    Injection molding is one of the most widely employed methods for manufacturing polymeric products. The final properties and the quality of an injection molded part are to a great extent affected by morphology. Thus, the prediction of microstructure formation is of technological importance, also for optimizing processing variables, in order to cut down on the expensive costs of tooling and the trial-and-error procedures. In this work, some injection molding tests were performed with the aim of studying the effects of packing pressure on morphology distribution. The resulting morphology of the moldings was in fact characterized by adopting different experimental techniques and, in order to underline the effects of holding pressure, it was compared with previous results gathered on samples obtained applying a lower holding pressure. Furthermore, the molding tests were simulated by means of a code developed at University of Salerno, which implements procedures able to model molecular orientation, crystallization kinetics and morphology evolution. The results obtained show that on increasing holding pressure the molecular orientation inside the samples increases, and simulations show that this is due mainly to the increase of relaxation time caused by the higher pressures. Furthermore, a sensible reduction of the percentage of α-phase is found on increasing the holding pressure, whereas the percentage of mesomorphic phase increases and a small fraction of γ-phase is found, which was not present in the samples molded at lower holding pressures.

  6. FIBER ORIENTATION IN INJECTION MOLDED LONG CARBON FIBER THERMOPLASTIC COMPOSITES

    SciTech Connect

    Wang, Jin; Nguyen, Ba Nghiep; Mathur, Raj N.; Sharma, Bhisham; Sangid, Michael D.; Costa, Franco; Jin, Xiaoshi; Tucker III, Charles L.; Fifield, Leonard S.

    2015-03-23

    A set of edge-gated and center-gated plaques were injection molded with long carbon fiber-reinforced thermoplastic composites, and the fiber orientation was measured at different locations of the plaques. Autodesk Simulation Moldflow Insight (ASMI) software was used to simulate the injection molding of these plaques and to predict the fiber orientation, using the anisotropic rotary diffusion and the reduced strain closure models. The phenomenological parameters of the orientation models were carefully identified by fitting to the measured orientation data. The fiber orientation predictions show very good agreement with the experimental data.

  7. 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.

  8. Injection Molding and its application to drug delivery.

    PubMed

    Zema, Lucia; Loreti, Giulia; Melocchi, Alice; Maroni, Alessandra; Gazzaniga, Andrea

    2012-05-10

    Injection Molding (IM) consists in the injection, under high pressure conditions, of heat-induced softened materials into a mold cavity where they are shaped. The advantages the technique may offer in the development of drug products concern both production costs (no need for water or other solvents, continuous manufacturing, scalability, patentability) and technological/biopharmaceutical characteristics of the molded items (versatility of the design and composition, possibility of obtaining solid molecular dispersions/solutions of the active ingredient). In this article, process steps and formulation aspects relevant to IM are discussed, with emphasis on the issues and advantages connected with the transfer of this technique from the plastics industry to the production of conventional and controlled-release dosage forms. Moreover, its pharmaceutical applications thus far proposed in the primary literature, intended as either alternative manufacturing strategies for existing products or innovative systems with improved design and performance characteristics, are critically reviewed.

  9. Metal Injection Molding of Alloy 718 for Aerospace Applications

    NASA Astrophysics Data System (ADS)

    Ott, Eric A.; Peretti, Michael W.

    2012-02-01

    The metal injection molding process, used in the automotive, medical, and consumer markets for several decades, was investigated for application to superalloys for small, complex-shaped, aerospace components. With sufficient control on processing, inclusion risks, and chemistry, the process can successfully be applied to superalloy 718 components. Assessments included tensile and fatigue property evaluation, characterization of microstructure, and development of an AMS specification.

  10. Injection Molding of Flat Glass Fiber Reinforced Thermoplastics

    NASA Astrophysics Data System (ADS)

    Tanaka, Kazuto; Katayama, Tsutao; Tanaka, Tatsuya; Anguri, Akihiro

    During an injection molding of composite materials, fiber attrition occurs and the average fiber length is reduced. In order to control the breakage of fibers and degradation of mechanical properties during processing, Flat glass Fiber (FF), that has oval cross-section shape, has been developed to use for glass fiber reinforced thermoplastic (GFRTP). Using FF as reinforcement of GFRTP has advantages as following: (1) Fluidity of FF is better than conventional Normal glass Fiber (NF) with 'circular' cross-section; (2) Fiber breakage during the injection molding process using FF is smaller than that using NF. In this study, the mechanical properties of FF and NF were compared for reinforcement of long fiber thermoplastics pellets (LFT pellets). We have also investigated the effect of screw design on fiber damage and the mechanical properties. The mechanical properties of specimens molded by FF reinforcement LFT (FF-LFT) pellets were superior to these of NF reinforcement LFT (NF-LFT) pellets. The former could give composites with higher fluidity and longer residual fiber length. Moreover, FF was able to strengthen injection-molded samples with higher fiber content than NF. Low shear type screw was effective to prevent the fiber attrition during plasticization process, hence leads to better mechanical properties of GFRTP

  11. Comparative Study Of Injection Molding Pressure Obtained From A Simulation And From A Monitored Mold

    NASA Astrophysics Data System (ADS)

    Peydró Rasero, M. A.; Juarez Varón, D.; Seguí Llinares, V. J.; Boronat Vitoria, T.

    2009-11-01

    The main objective of the present work is to identify the exact of behavior of ABS when it is injected into a mold. We study the conditions and the most important parameters of the process, emphasizing the injection pressure and cycle time. Another objective is to characterize two of the properties of the material that most influence the injection of thermoplastic materials. For the calculation of viscosity, a capillary rheometer was used, and a Differential Scanning Calorimetry (DSC) was used to determinate specific heat capacity. The final objective of the work is to quantify the accuracy of the data obtained by a computer aided simulation to help determine the best processing conditions. To this end, results obtained from this simulation and results obtained from a mold monitored with sensors were compared. Finally, the possible causes of the differences observed in this comparison are presented.

  12. FPGA-Based Multiprocessor System for Injection Molding Control

    PubMed Central

    Muñoz-Barron, Benigno; Morales-Velazquez, Luis; Romero-Troncoso, Rene J.; Rodriguez-Donate, Carlos; Trejo-Hernandez, Miguel; Benitez-Rangel, Juan P.; Osornio-Rios, Roque A.

    2012-01-01

    The plastic industry is a very important manufacturing sector and injection molding is a widely used forming method in that industry. The contribution of this work is the development of a strategy to retrofit control of an injection molding machine based on an embedded system microprocessors sensor network on a field programmable gate array (FPGA) device. Six types of embedded processors are included in the system: a smart-sensor processor, a micro fuzzy logic controller, a programmable logic controller, a system manager, an IO processor and a communication processor. Temperature, pressure and position are controlled by the proposed system and experimentation results show its feasibility and robustness. As validation of the present work, a particular sample was successfully injected. PMID:23202036

  13. FPGA-based multiprocessor system for injection molding control.

    PubMed

    Muñoz-Barron, Benigno; Morales-Velazquez, Luis; Romero-Troncoso, Rene J; Rodriguez-Donate, Carlos; Trejo-Hernandez, Miguel; Benitez-Rangel, Juan P; Osornio-Rios, Roque A

    2012-10-18

    The plastic industry is a very important manufacturing sector and injection molding is a widely used forming method in that industry. The contribution of this work is the development of a strategy to retrofit control of an injection molding machine based on an embedded system microprocessors sensor network on a field programmable gate array (FPGA) device. Six types of embedded processors are included in the system: a smart-sensor processor, a micro fuzzy logic controller, a programmable logic controller, a system manager, an IO processor and a communication processor. Temperature, pressure and position are controlled by the proposed system and experimentation results show its feasibility and robustness. As validation of the present work, a particular sample was successfully injected.

  14. Influence of melt mixer on injection molding of thermoset elastomers

    NASA Astrophysics Data System (ADS)

    Rochman, Arif; Zahra, Keith

    2016-10-01

    One of the drawbacks in injection molding is that the plasticizing screw is short such that polymers having high concentrations of additives, such as thermoset elastomers, might not mix homogeneously within the short period of time during the plasticizing stage. In this study, various melt mixers inside the nozzle chamber, together forming a mixing nozzle, were developed. Three different materials were investigated, namely nitrile butadiene rubber (NBR), ethylene propylene-diene monomer (EPDM) and fluorocarbon (FKM). The use of these melt mixers resulted in better homogeneity and properties of the molded parts despite a curing time reduction of 10 s. This was due to the increase in mixing and shearing introduced a higher rate of crosslinking formation in the molded parts.

  15. Injection molding of thermoplastic elastomers for microstructured substrates

    NASA Astrophysics Data System (ADS)

    Birkar, Smita

    Amorphous and semi-crystalline thermoplastic polymers have been widely investigated for injection molding of parts with microstructured surfaces. Microstructured surfaces injection molded from thermoplastic elastomers have emerging applications as superhydrobic surfaces and patterned adhesives, but there is a limited understanding of the factors affecting replication with these materials. This research was a continued investigation of block copolymer thermoplastic elastomers as well as the first in-depth examination of thermoplastic vulcanizates for injection molding microfeatures. The first focus of this research was the interactions between tooling aspect ratio and feature orientation (negative and positive tooling) and thermoplastic elastomer hard segment content on microfeature replication. Electroformed nickel tooling having positive and negative features with different geometries and aspect ratios of 0.02:1 to 2:1 were molded from three copolyester thermoplastic elastomers with similar chemistry and different hardness values. The tooling and part features were characterized for feature depth and height as well as feature definition using scanning electron microscopy and optical profilometry. Results were correlated with elastomer properties. In the second parts of this research, the effects of microfeature spacing on the replication of thermoplastic elastomer features was investigated using micropillars with two diameters (10 and 20 mum) and three spacing ratios (0.5:1, 1:1, and 2:1). The tooling and part features were characterized for feature depth and height as well as feature definition using scanning electron microscopy and optical profilometry. Feature spacing significantly affected the replication of micropillars using a thermoplastic elastomer. This replication was competition between cooling and pressurization of the melt. Wider spacing between smaller features allowed cooling in the tooling lands to dominate the feature filling. Higher pressures did

  16. Direct processing of continuous fibers onto injection molding machines

    NASA Astrophysics Data System (ADS)

    Truckenmueller, F. M.

    1993-06-01

    A new injection molding process 'DIF' (Direct Incorporation of Continuous Fibers) is proposed whereby roving strands are directly incorporated into the polymer melt by using a reciprocating-screw-plasticating unit. The DIF-technology offers the possibility to substitute the relatively expensive pultrusion process which is used to produce long fiber pellets. Furthermore it can be used as a fast and flexible R&D tool. In order to improve fiber dispersion with minimum fiber breakage a new mixing non-return-valve 'LFMR' (Long Fiber Mixing Ring) was developed based on the 'Twente Mixing Ring'; Its mixing capacity and influence on processing characteristics, fiber breakage and property profile of the injection molded parts is examined and compared to a general purpose non-return-valve of the ring type. The results of fundamental mechanical and physical property investigations are presented including dispersion of fiber clusters and bundles, fiber length distribution and fiber orientation.

  17. Injection molding of iPP samples in controlled conditions and resulting morphology

    SciTech Connect

    Sessa, Nino De Santis, Felice Pantani, Roberto

    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.

  18. Effects of powder characteristics on injection molding and burnout cracking

    SciTech Connect

    Bandyopadhyay, G.; French, K.W. )

    1994-03-01

    Silicon nitride particle size and size distributions were varied widely to determine their effects on burnout cracking of injection-molded test parts containing thick and thin sections. Elimination of internal cracking required significant burnout shrinkage, which did not occur by changes of particle size and size distribution. However, isopressing of test parts after burnout provided the dimensional shrinkage necessary for producing crack-free components.

  19. 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

  20. Materials processing research opportunities in powder injection molding

    SciTech Connect

    German, R.M.

    1995-12-31

    Materials processing is an active area with many research opportunities for advanced instrumentation, control, and modeling. Among new materials processing routes, powder injection molding (PIM) has rapidly grown from a curiosity to a viable production technique over just a few years. This manufacturing technique is applicable to all materials, and is the preferred fabrication route for many complex-shaped, high-performance components for surgical tools, computer hardware, automotive systems, consumer products, and turbine components. This presentation introduces the use of a computer controlled injection molding machine to shape powders (metal, carbide, composite, and ceramic) in a high productivity setting. After molding the organic is extracted and the powder structure is sintered to full density. Much research is needed in process modeling, control, inspection, and optimization. This presentation summarizes the basic technology and several important factors relevant to manufacturing. An important development is in minimization of molding defects via closed-loop feedback control using pressure, temperature, and optical sensors. Recent progress has occurred using in situ guided waves for ultrasonic inspection of the molded part. Neural networks are being generated to allow assessment of processing changes as required from the integrated robot, visual imaging, pressure, and ultrasonic sensors. Similar, but less refined efforts are occurring in die compaction technology. As another example, computer simulation of heat transfer is needed during sintering to understand sources of component warpage during densification. A furnace equipped with visual imaging and residual gas analysis is being used to assist in verification of such computer simulations. These tools are still in the research stage, so future integration into the manufacturing environment will bring new challenges.

  1. Investigations on injection molded, glass-fiber reinforced polyamide 6 integral foams using breathing mold technology

    NASA Astrophysics Data System (ADS)

    Roch, A.; Kehret, L.; Huber, T.; Henning, F.; Elsner, P.

    2015-05-01

    Investigations on PA6-GF50 integral foams have been carried out using different material systems: longfiber- and shortfiber-reinforced PA6 as well as unreinforced PA6 as a reference material. Both chemical and physical blowing agents were applied. Breathing mold technology (decompression of the mold) was selected for the foaming process. The integral foam design, which can be conceived as a sandwich structure, helps to save material in the neutral axis area and maintains a distance between load-bearing, unfoamed skin layers. For all test series an initial mold gap of 2.5 mm was chosen and the same amount of material was injected. In order to realize different density reductions, the mold opening stroke was varied. The experiments showed that, at a constant mass per unit area, integral polyamide 6 foams have a significantly higher bending stiffness than compact components, due to their higher area moment of inertia after foaming. At a constant surface weight the bending stiffness in these experiments could be increased by up to 600 %. Both shortfiber- and longfiber-reinforced polyamide 6 showed an increase in energy absorption during foaming.

  2. Injection-molded capsular device for oral pulsatile release: development of a novel mold.

    PubMed

    Zema, Lucia; Loreti, Giulia; Macchi, Elena; Foppoli, Anastasia; Maroni, Alessandra; Gazzaniga, Andrea

    2013-02-01

    The development of a purposely devised mold and a newly set up injection molding (IM) manufacturing process was undertaken to prepare swellable/erodible hydroxypropyl cellulose-based capsular containers. When orally administered, such devices would be intended to achieve pulsatile and/or colonic time-dependent delivery of drugs. An in-depth evaluation of thermal, rheological, and mechanical characteristics of melt formulations/molded items made of the selected polymer (Klucel® LF) with increasing amounts of plasticizer (polyethylene glycol 1500, 5%-15% by weight) was preliminarily carried out. On the basis of the results obtained, a new mold was designed that allowed, through an automatic manufacturing cycle of 5 s duration, matching cap and body items to be prepared. These were subsequently filled and coupled to give a closed device of constant 600 μm thickness. As compared with previous IM systems having the same composition, such capsules showed improved closure mechanism, technological properties, especially in terms of reproducibility of the shell thickness, and release performance. Moreover, the ability of the capsular container to impart a constant lag phase before the liberation of the contents was demonstrated irrespective of the conveyed formulation.

  3. Injection-molded replication of binary optic structures

    NASA Astrophysics Data System (ADS)

    Nisper, Jon K.

    1995-12-01

    Application of molded plastics to precision optical systems has required significant advances in both the design and fabrication of these optical components. Tighter fabrication tolerances and improved transmitted wavefront quality are being achieved with each passing year. Recently, interest has focused on the particular challenge of injection molded diffractive optic structures. Binary optics are generated using VLSI techniques of microlithography and dry etching to produce a diffractive structure with submicron accuracy. The cost incurred in wafer scale fabrication of individual elements is quite high. By precise mastering, detailed mold design and careful process control, binary optics can be successfully replicated in plastic materials allowing significantly lower costs. This paper will address three specific applications of mass produced diffractive structures. A hybrid refractive/diffractive lens has been designed and produced in acrylic; a set of complex diffractive fanout gratings has been produced in acrylic, polycarbonate, polymethylpentene, and cyclic olefin copolymer; and a diode laser collimator/corrector has recently been successfully molded in polycarbonate. Detailed results highlighting the fidelity of the replicated surface will be included.

  4. Applications of polyamide/cellulose fiber/wollastonite composites for microcellular injection molding

    Treesearch

    Herman Winata; Lih-Sheng Turng; Daniel F. Caulfield; Tom Kuster; Rick Spindler; Rod Jacobson

    2003-01-01

    In this study, a cellulose-fiber-reinforced Polyamide-6 (PA-6) composite, a hybrid composite (PA-6/cellulose/Wollastonite), and the neat PA-6 resin were injection molded into ASTM test–bar samples with conventional and microcellular injection molding. The impact and tensile strengths of molded samples were measured and the Scanning Electron Microscopy (SEM) images were...

  5. 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.

  6. Respiratory symptoms associated with the use of azodicarbonamide foaming agent in a plastics injection molding facility.

    PubMed

    Whitehead, L W; Robins, T G; Fine, L J; Hansen, D J

    1987-01-01

    Respiratory health variables were studied cross-sectionally in 227 employees of a plastics molding facility where numerous complaints had been apparently associated with the use of azodicarbonamide foaming agent in injection molding. Pre- and postshift respiratory status measures and azodicarbonamide concentrations were also obtained for 17 employees. Cross-sectional pulmonary function differences by injection molding status were not observed. Modest decrements in pulmonary function measures were observed between start and end of shift but with no dose-effect relationship. A strong association was observed for injection molding workers for eye/nose/throat irritation, cough, and wheezing. Additionally, wheezing, chest tightness, and symptoms of chronic bronchitis were strongly associated with work in injection molding during periods in which azodicarbonamide was in use. These results suggest respiratory symptom causation by some combination of azodicarbonamide itself, reaction products of azodicarbonamide formed during injection molding, or other unidentified agents uniquely associated with the process of injection molding with azodicarbonamide foaming agent.

  7. Investigation of Properties of Powder Injection-Molded Steatites

    NASA Astrophysics Data System (ADS)

    Urtekin, L.; Uslan, I.; Tuc, B.

    2012-03-01

    In this study, the mechanical and micro-structural properties of injection-molded steatites were investigated experimentally. Initially, steatite powders and binders of polyethylene glycol (PEG), polypropylene (PP), and stearic aside (SA) were mixed to prepare the feedstock. The mixing powders were granulated using the extruder. The short granules in cylindrical shapes were used as the feedstock in the injection-molding operations. Solvent- and thermal-debinding processes were applied to the green samples after the molding. The samples were sintered at 1300 °C for 4 h, and a theoretical density of 98-99% was achieved. Three-point bending and tensile tests were performed on the samples which were sintered at 1200-1300 °C. The maximum three-point bending and tensile strength values were found as 154 and 47 MPa, respectively. The morphology of fractured surface was done by scanning electron microscopy whereas porosity investigations were carried out using the same microscopy. Grain growth and structure on the specimens were also investigated using transmission electron microscopy.

  8. 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.

  9. 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

  10. Ion channel recordings on an injection-molded polymer chip.

    PubMed

    Tanzi, Simone; Matteucci, Marco; Christiansen, Thomas Lehrmann; Friis, Søren; Christensen, Mette Thylstrup; Garnaes, Joergen; Wilson, Sandra; Kutchinsky, Jonatan; Taboryski, Rafael

    2013-12-21

    In this paper, we demonstrate recordings of the ion channel activity across the cell membrane in a biological cell by employing the so-called patch clamping technique on an injection-molded polymer microfluidic device. The findings will allow direct recordings of ion channel activity to be made using the cheapest materials and production platform to date and with the potential for very high throughput. The employment of cornered apertures for cell capture allowed the fabrication of devices without through holes and via a scheme comprising master origination by dry etching in a silicon substrate, electroplating in nickel and injection molding of the final part. The most critical device parameters were identified as the length of the patching capillary and the very low surface roughness on the inside of the capillary. The cross-sectional shape of the orifice was found to be less critical, as both rectangular and semicircular profiles seemed to have almost the same ability to form tight seals with cells with negligible leak currents. The devices were functionally tested using human embryonic kidney cells expressing voltage-gated sodium channels (Nav1.7) and benchmarked against a commercial state-of-the-art system for automated ion channel recordings. These experiments considered current-voltage (IV) relationships for activation and inactivation of the Nav1.7 channels and their sensitivity to a local anesthetic, lidocaine. Both IVs and lidocaine dose-response curves obtained from the injection-molded polymer device were in good agreement with data obtained from the commercial system.

  11. Capabilities Of Micro Powder Injection Molding For Microparts Manufacturing

    NASA Astrophysics Data System (ADS)

    Kong, X.; Barriere, T.; Gelin, J. C.

    2011-01-01

    The Micro-PIM processing technology satisfies the increasing demand in terms of smaller parts and miniaturization. Research works in this area have been carried out at FEMTO-ST Institute by performing the injection molding with 316L stainless steel fine powders and polymer binders. Several formulations with different proportion of powders and binders as well various polymers have been tested, and then a well adapted one has been selected. The process to select the well adapted formulation and the rheological characteristics of the feedstock realized according with the selected formulation are also detailed. Several test specimens have been successfully manufactured.

  12. The technology and commercial status of powder-injection molding

    NASA Astrophysics Data System (ADS)

    Bose, Animesh

    1995-08-01

    The process of powder-injection molding (PIM) is a viable and competitive commercial technique that is being used to process complex-shaped parts of various materials in moderate to high volumes. The hey advantage of the process is its unique ability to combine materials selection flexibility with the complex shape-forming ability of plastics. Although the PIM process has been discussed in the open literature for more than quarter of a century, it has become a commercial reality only during the last decade or so. Currently, there is a tremendous interest in this unique technology throughout the world. As a result, the PIM industry is poised for significant growth.

  13. Modeling injection molding of net-shape active ceramic components.

    SciTech Connect

    Baer, Tomas; Cote, Raymond O.; Grillet, Anne Mary; Yang, Pin; Hopkins, Matthew Morgan; Noble, David R.; Notz, Patrick K.; Rao, Rekha Ranjana; Halbleib, Laura L.; Castaneda, Jaime N.; Burns, George Robert; Mondy, Lisa Ann; Brooks, Carlton, F.

    2006-11-01

    To reduce costs and hazardous wastes associated with the production of lead-based active ceramic components, an injection molding process is being investigated to replace the current machining process. Here, lead zirconate titanate (PZT) ceramic particles are suspended in a thermoplastic resin and are injected into a mold and allowed to cool. The part is then bisque fired and sintered to complete the densification process. To help design this new process we use a finite element model to describe the injection molding of the ceramic paste. Flow solutions are obtained using a coupled, finite-element based, Newton-Raphson numerical method based on the GOMA/ARIA suite of Sandia flow solvers. The evolution of the free surface is solved with an advanced level set algorithm. This approach incorporates novel methods for representing surface tension and wetting forces that affect the evolution of the free surface. Thermal, rheological, and wetting properties of the PZT paste are measured for use as input to the model. The viscosity of the PZT is highly dependent both on temperature and shear rate. One challenge in modeling the injection process is coming up with appropriate constitutive equations that capture relevant phenomenology without being too computationally complex. For this reason we model the material as a Carreau fluid and a WLF temperature dependence. Two-dimensional (2D) modeling is performed to explore the effects of the shear in isothermal conditions. Results indicate that very low viscosity regions exist near walls and that these results look similar in terms of meniscus shape and fill times to a simple Newtonian constitutive equation at the shear-thinned viscosity for the paste. These results allow us to pick a representative viscosity to use in fully three-dimensional (3D) simulation, which because of numerical complexities are restricted to using a Newtonian constitutive equation. Further 2D modeling at nonisothermal conditions shows that the choice of

  14. Fabrication of Composite Material Using Gettou Fiber by Injection Molding

    NASA Astrophysics Data System (ADS)

    Setsuda, Roy; Fukumoto, Isao; Kanda, Yasuyuki

    This study investigated the mechanical properties of composite using gettou (shell ginger) fiber as reinforcement fabricated from injection molding. Gettou fiber is a natural fiber made from gettou, a subtropical plant that is largely abundant in Okinawa, Japan. We used the stem part of gettou plant and made the gettou fiber by crushing the stem. The composite using gettou fiber contributed to low shrinkage ratio, high bending strength and high flexural modulus. The mechanical strength of composite using long gettou fiber showed higher value than composite using short gettou fiber. Next, because gettou is particularly known for its anti-mold characteristic, we investigated the characteristic in gettou plastic composite. The composite was tested against two molds: aspergillius niger and penicillium funiculosum. The 60% gettou fiber plastic composite was found to satisfy the JISZ2801 criterion. Finally, in order to predict the flexural modulus of composite using gettou fiber by Halpin-Tsai equation, the tensile elastic modulus of single gettou fiber was measured. The tendency of the experimental results of composite using gettou fiber was in good agreement with Halpin-Tsai equation.

  15. Molds

    MedlinePlus

    ... cause health problems. Inhaling or touching mold or mold spores may cause allergic reactions or asthma attacks in sensitive people. Molds can cause fungal infections. In addition, mold exposure ...

  16. Foaming morphology control of microcellular injection molded parts with gas counter pressure and dynamic mold temperature control

    NASA Astrophysics Data System (ADS)

    Shiu, Tai-Yi; Huang, Chao-Tsai; Chang, Rong-Yu; Hwang, Shyh-Shin

    2014-05-01

    Microcellular injection molding process is a promising solution for products with special requirements such as weight reduction, extra thin wall, high dimensional stability, clamping force reduction, etc. Despite microcellular foaming application used in reciprocating screw injection molding machine was built more than a decade, some limitations, such as poor surface quality or poor foaming control, confine the usage of this technology. Earlier CAE simulation tool for microcellular injection molding was not successful due to insufficient physical and computational considerations, limited by complicated bubble growth mechanism; so that, an economic and efficient tool for examining foaming quality of injection foaming product was lack. In this study, a recent developed three-dimensional simulation tool is used to predict injection foaming process. Predictions are carried out with commodity polypropylene and polystyrene with nitrogen and carbon dioxide supercritical fluids (SCFs). Comparisons of simulations between microcellular injection molding with and without counter pressure are discussed to provide insights into the correlation of surface quality and cell size distribution near the surface of product. Furthermore, comparisons between simulation predictions and experimental results of molding process, which is featured with dynamic mold temperature and gas counter pressure, are given for understanding quality improvement by controlling foaming morphology, and benefit of industrial application.

  17. Fiber Reinforcement in Injection Molded Nylon 6/6 Spur Gears

    NASA Astrophysics Data System (ADS)

    Senthilvelan, S.; Gnanamoorthy, R.

    2006-07-01

    Injection molded polymer composite gears are being used in many power and or motion transmission applications. In order to widen the utilization of reinforced polymers for precision motion transmission and noise less applications, the accuracy of molded gears should be increased. Since the injection molded gear accuracy is significantly influenced by the material shrinkage behaviour, there is a need to understand the influence of fiber orientation and gate location on part shrinkage behaviour and hence the gear accuracy. Unreinforced and 20% short glass fiber reinforced Nylon 6/6 spur gears were injection molded in the laboratory and computer aided simulations of gear manufacturing was also carried out. Results of the mold flow simulation of gear manufacturing were correlated with the actual fiber orientation and measured major geometrical parameters of the molded gears. Actual orientation of the fibers near the tooth profile, weld line region and injection points of molded gears were observed using optical microscope and correlated with predicted fiber orientation.

  18. A Study on the Optimization for Metal Injection Molding Process

    NASA Astrophysics Data System (ADS)

    Jung, M. K.; Jang, K. C.; Lee, D. G.; Kim, M. H.

    2011-01-01

    The objective of this paper is study the optimization for metal injection molding process by using the design of experiments (DOE) and numerical analysis. In order to determine optimal process parameters, experiment and computerized analysis have been performed for various process conditions. Proper coded and uncoded regression equations and optimization for responses (flow front temperature, part weight, filling time, cycle time, and volumetric shrinkage) achieved from studying and verifying interrelation of the factors. About 70% of whole binder extracted within about 10 minutes and temperature of solvent is higher, the debinding rate is fast. 50° C was the most suitable condition for solvent extraction because of crack occurrence on green body at 55° C. It took about 14.5 hours to perform secondary thermal debinding, which was only about 35% of the entire time taken compared with single thermal debinding process, even if it considers solvent extraction time required. Therefore, the applied method greatly reduces the debinding time. The excellent process capability showed that the PPM total and Z.Bench were 9,946.8 and 2.33 showing good quality rate of around 99.01% and sigma level of 3.83. As a result, the process and optimization have been improved, and the proposed approach could be successfully reflected on the metal injection molding.

  19. CREEP MODELING FOR INJECTION-MOLDED LONG-FIBER THERMOPLASTICS

    SciTech Connect

    Nguyen, Ba Nghiep; Kunc, Vlastimil; Bapanapalli, Satish K.

    2008-06-30

    This paper proposes a model to predict the creep response of injection-molded long-fiber thermoplastics (LFTs). The model accounts for elastic fibers embedded in a thermoplastic resin that exhibits the nonlinear viscoelastic behavior described by the Schapery’s model. It also accounts for fiber length and orientation distributions in the composite formed by the injection-molding process. Fiber length and orientation distributions were measured and used in the analysis that applies the Eshelby’s equivalent inclusion method, the Mori-Tanaka assumption (termed as the Eshelby-Mori-Tanaka approach) and the fiber orientation averaging technique to compute the overall strain increment resulting from an overall constant applied stress during a given time increment. The creep model for LFTs has been implemented in the ABAQUS finite element code via user-subroutines and has been validated against the experimental creep data obtained for long-glass-fiber/polypropylene specimens. The effects of fiber orientation and length distributions on the composite creep response are determined and discussed.

  20. 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.

  1. 3D Fiber Orientation Simulation for Plastic Injection Molding

    NASA Astrophysics Data System (ADS)

    Lin, Baojiu; Jin, Xiaoshi; Zheng, Rong; Costa, Franco S.; Fan, Zhiliang

    2004-06-01

    Glass fiber reinforced polymer is widely used in the products made using injection molding processing. The distribution of fiber orientation inside plastic parts has direct effects on quality of molded parts. Using computer simulation to predict fiber orientation distribution is one of most efficient ways to assist engineers to do warpage analysis and to find a good design solution to produce high quality plastic parts. Fiber orientation simulation software based on 2-1/2D (midplane /Dual domain mesh) techniques has been used in industry for a decade. However, the 2-1/2D technique is based on the planar Hele-Shaw approximation and it is not suitable when the geometry has complex three-dimensional features which cannot be well approximated by 2D shells. Recently, a full 3D simulation software for fiber orientation has been developed and integrated into Moldflow Plastics Insight 3D simulation software. The theory for this new 3D fiber orientation calculation module is described in this paper. Several examples are also presented to show the benefit in using 3D fiber orientation simulation.

  2. Injection molded polymeric micropatterns for bone regeneration study.

    PubMed

    Zanchetta, Erika; Guidi, Enrica; Della Giustina, Gioia; Sorgato, Marco; Krampera, Mauro; Bassi, Giulio; Di Liddo, Rosa; Lucchetta, Giovanni; Conconi, Maria Teresa; Brusatin, Giovanna

    2015-04-08

    An industrially feasible process for the fast mass-production of molded polymeric micro-patterned substrates is here presented. Microstructured polystyrene (PS) surfaces were obtained through micro injection molding (μIM) technique on directly patterned stamps realized with a new zirconia-based hybrid spin-on system able to withstand 300 cycles at 90 °C. The use of directly patterned stamps entails a great advantage on the overall manufacturing process as it allows a fast, flexible, and simple one-step process with respect to the use of milling, laser machining, electroforming techniques, or conventional lithographic processes for stamp fabrication. Among the different obtainable geometries, we focused our attention on PS replicas reporting 2, 3, and 4 μm diameter pillars with 8, 9, 10 μm center-to-center distance, respectively. This enabled us to study the effect of the substrate topography on human mesenchymal stem cells behavior without any osteogenic growth factors. Our data show that microtopography affected cell behavior. In particular, calcium deposition and osteocalcin expression enhanced as diameter and interpillar distance size increases, and the 4-10 surface was the most effective to induce osteogenic differentiation.

  3. Rapid clinical diagnostics assays using injection-molded planar waveguides

    NASA Astrophysics Data System (ADS)

    Herron, James N.; Wang, Hsu-Kun; Terry, Allen H.; Durtschi, Jacob D.; Tan, Lyndon; Astill, Mark E.; Smith, Richard S.; Christensen, Douglas A.

    1998-04-01

    The goal of our research program is to develop an evanescent wave immunoassay system that can be used in point-of-care and critical care settings. Several key attributes are required to accomplish this goal: (1) the assay system should be at least as sensitive as present day immunoassays; (2) assay time should be 5 minutes or less; (3) the assay protocol should be relatively simple; (4) the sensor should be capable of performing more than one assay on a single specimen; (5) the assay system should be able to accommodate specimens such as serum, plasma and whole blood; and (6) the sensor should be an inexpensive, disposable cartridge. Our laboratory has developed an injection-molded planar waveguide sensor that meets most, if not all, of these attributes. This sensor has been evaluated in a number of different immunoassays for analytes such as bovine serum albumin, human chorionic gonadotrophin, creatine phosphokinase MB and cardiac troponin I.

  4. A senior manufacturing laboratory for determining injection molding process capability

    NASA Technical Reports Server (NTRS)

    Wickman, Jerry L.; Plocinski, David

    1992-01-01

    The following is a laboratory experiment designed to further understanding of materials science. This subject material is directed at an upper level undergraduate/graduate student in an Engineering or Engineering Technology program. It is assumed that the student has a thorough understanding of the process and quality control. The format of this laboratory does not follow that which is normally recommended because of the nature of process capability and that of the injection molding equipment and tooling. This laboratory is instead developed to be used as a point of departure for determining process capability for any process in either a quality control laboratory or a manufacturing environment where control charts, process capability, and experimental or product design are considered important topics.

  5. Microcellular foam injection molding with cellulose nanofibers (CNFs)

    NASA Astrophysics Data System (ADS)

    Ohshima, Masahiro; Kubota, Masaya; Ishihara, Shota; Hikima, Yuta; Sato, Akihiro; Sekiguchi, Takafumi

    2016-03-01

    Cellulose nanofibers (CNFs) nanocomposites polypropylene foams are prepared by microcellular foam injection molding with core-back operation. The modified CNFs were blended with isotactic-polypropylene (i-PP) at different CNFs weight percentages and foamed to investigate the effect of CNFs on cell morphology. CNFs in i-PP increased the elastic modulus and induced a strain hardening behavior. CNFs also shifted the crystallization temperature of i-PP to higher temperature and enhanced crystallization. With these changes in rheological and thermal properties, CNFs could reduce the cell size and increase the cell density of the foams. By adjusting the core-back timing i.e., foaming temperature, the closed cell and the nano-fibrillated open cellular structure could be produced. The flexural modulus and bending strength of foams were measured by three point flexural tester. The flexural modulus and bending strength were increased as the CNFs content in i-PP was increased at any foam expansion ratio.

  6. Tensile Characterization of Injection-Molded Fuzzy Glass Fiber/Nylon Composite Material

    DTIC Science & Technology

    2016-05-01

    Composite Material by Michael A Minnicino and Christopher Goodeaux Approved for public release; distribution is...Army Research Laboratory Tensile Characterization of Injection-Molded Fuzzy Glass Fiber/Nylon Composite Material by Michael A Minnicino...Characterization of Injection-Molded Fuzzy Glass Fiber/Nylon Composite Material 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER

  7. Effect of cross sectional geometry on PDMS micro peristaltic pump performance: comparison of SU-8 replica molding vs. micro injection molding.

    PubMed

    Graf, Neil J; Bowser, Michael T

    2013-10-07

    Two different fabrication methods were employed to fabricate micropumps with different cross-sectional channel geometries. The first was to fabricate rectangular cross-sectional microchannel geometries using the well known fabrication method of replica molding (REM). The second, and far less utilized fabrication technique, was to create microchannel molds using an in-house fabricated handheld micro injection molding apparatus. The injection mold apparatus was designed for use with elastomeric room temperature vulcanization (RTV) polymers, as opposed to most other injection molding machines, which are designed for use with thermoplastic polymers. The injection mold's bottom plate was used as a microchannel molding template. The molding template was created by threading a small-diameter wire (150 μm or less) through the injection mold's bottom plate, with subsequent adhesion and smoothing of a thin piece of aluminum foil over the wire-raised injection mold template. When molded against, the template produced a rounded/Gaussian-shaped PDMS microchannel. The design of the injection mold will be presented, along with a direct comparison for micropump performance metrics such as flow rate, valving characteristics, and maximum backpressures attainable for each of the respective micropump channel geometries.

  8. 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.

  9. 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.

  10. Low Cost Injection Mold Creation via Hybrid Additive and Conventional Manufacturing

    SciTech Connect

    Dehoff, Ryan R.; Watkins, Thomas R.; List, III, Frederick Alyious; Carver, Keith; England, Roger

    2015-12-01

    The purpose of the proposed project between Cummins and ORNL is to significantly reduce the cost of the tooling (machining and materials) required to create injection molds to make plastic components. Presently, the high cost of this tooling forces the design decision to make cast aluminum parts because Cummins typical production volumes are too low to allow injection molded plastic parts to be cost effective with the amortized cost of the injection molding tooling. In addition to reducing the weight of components, polymer injection molding allows the opportunity for the alternative cooling methods, via nitrogen gas. Nitrogen gas cooling offers an environmentally and economically attractive cooling option, if the mold can be manufactured economically. In this project, a current injection molding design was optimized for cooling using nitrogen gas. The various components of the injection mold tooling were fabricated using the Renishaw powder bed laser additive manufacturing technology. Subsequent machining was performed on the as deposited components to form a working assembly. The injection mold is scheduled to be tested in a projection setting at a commercial vendor selected by Cummins.

  11. Characterization of polymeric binders for Metal Injection Molding (MIM) process

    NASA Astrophysics Data System (ADS)

    Adames, Juan M.

    The Metal Injection Molding (MIM) process is an economically attractive method of producing large amounts of small and complex metallic parts. This is achieved by combining the productivity of injection molding with the versatility of sintering of metal particulates. In MIM, the powdered metal is blended with a plastic binder to obtain the feedstock. The binder imparts flowability to the blend at injection molding conditions and strength at ambient conditions. After molding, the binder is removed in a sequence of steps that usually involves solvent-extraction and polymer burn-out. Once the binder is removed, the metal particles are sintered. In this research several topics of the MIM process were studied to understand how the polymeric binder, similar to the one used in the sponsoring company, works. This was done by examining the compounding and water debinding processes, the rheological and thermal properties, and the microstructure of the binder/metal composite at different processing stages. The factors studied included the metal contents, the composition of the binder and the processing conditions. The three binders prepared during the course of this research were blends of a polyolefin, polyoxymethylene copolymer (POM) and a water-soluble polymer (WSP). The polyolefin resins included polypropylene (PP), high-density polyethylene (HDPE) and linear low-density polyethylene (LLDPE). The powdered metal in the feedstocks was 316 L stainless steel. The compounding studies were completed in an internal mixer under different conditions of temperature, rotational speed and feedstock composition. It was found that the metal concentration was the most important factor in determining the torque evolution curves. The observation of microstructure with Scanning Electron Microscope (SEM) at different stages during compounding revealed that the metal particles neither agglomerate nor touch each other. The liquid extraction of the water-soluble polymer (WSP) from the molded

  12. Flexural Properties of Injection-Molded Bamboo/pbs Composites

    NASA Astrophysics Data System (ADS)

    Ohkita, Kazuya; Takagi, Hitoshi

    In recent years, from an environmental perspective, there has been increasing interest in the change to a sustainable society. The use of natural-fiber-reinforced biodegradable composites has been proposed as one solution. Bamboo is an often used renewable bio-resource; it has an inherent advantage of rapid growth. Polybutylene succinate (PBS), used as matrix resin, has biodegradable characteristics. This paper describes flexural properties of bamboo/PBS composites prepared by injection molding. The following results were obtained. The flexural modulus was improved with increasing bamboo powder contents when the cylinder temperature of the injection molder was 140°C. However, the flexural strength showed the opposite tendency to be decreased with increasing bamboo powder contents. An SEM photomicrograph of the fracture surface for bamboo/PBS composites showed typical fracture behavior of pull-out fibers without fiber fracture. Furthermore, there was no adhesion of PBS resin on the bamboo fiber surface. Processing conditions affected mechanical properties of bamboo/PBS composites, imparting higher flexural strength and flexural modulus at high cylinder temperatures such as 180°C and 200°C.

  13. Warpage Generation Mechanism by Cooling Speed Distribution in Actual Injection Molding

    NASA Astrophysics Data System (ADS)

    Satoh, Kazuhito; Matsubara, Eiji; Yamabe, Masashi

    In some cases, warpage failure occurs in the injection molding plate. This warpage can be predicted by using injection molding CAE. However, the prediction accuracy is not enough in the warpage analysis of injection molding CAE. The warpage generation mechanism changes according to the material and shape. The mechanism has not been clarified in each condition. For example, there is difference in the cooling speed of the real injection plate in each position. In this report, we considered the influence of the difference of mold temperature on warpage, assuming the mold temperature to be an asymmetric condition. And the following conclusions were arrived at. Moreover, upon examining the influence of mold temperature difference on warpage of PP plate, the following conclusions were obtained. 1) The amount of warpage grows in an asymmetrical mold temperature condition. The amount of warpage increases in the case of high mold temperature even if the difference of temperature between fixed side and moved side is constant. 2) In the case of asymmetrical mold temperature, the distribution of crystallinity becomes asymmetrical in the thickness direction. However, the thermal expansion coefficient is isotropy and constant. 3) The key factor of warpage in asymmetrical mold temperature conditions in PP is induced by thermal effect. 4) The resin flow of asymmetrical mold temperature conditions in PP becomes a symmetrical flow. This is thought to be influenced by heat of shearing and latent heat of crystallization. 5) Even under the same mold temperature asymmetric condition, differences in material cause the influence of mold temperature on flow to differ.

  14. Friction behavior of ceramic injection-molded (CIM) brackets.

    PubMed

    Reimann, Susanne; Bourauel, Christoph; Weber, Anna; Dirk, Cornelius; Lietz, Thomas

    2016-07-01

    Bracket material, bracket design, archwire material, and ligature type are critical modifiers of friction behavior during archwire-guided movement of teeth. We designed this in vitro study to compare the friction losses of ceramic injection-molded (CIM) versus pressed-ceramic (PC) and metal injection-molded (MIM) brackets-used with different ligatures and archwires-during archwire-guided retraction of a canine. Nine bracket systems were compared, including five CIM (Clarity™ and Clarity™ ADVANCED, both by 3M Unitek; discovery(®) pearl by Dentaurum; Glam by Forestadent; InVu by TP Orthodontics), two PC (Inspire Ice by Ormco; Mystique by DENTSPLY GAC), and two MIM (discovery(®) and discovery(®) smart, both by Dentaurum) systems. All of these were combined with archwires made of either stainless steel or fiberglass-reinforced resin (remanium(®) ideal arch or Translucent pearl ideal arch, both by Dentaurum) and with elastic ligatures or uncoated or coated stainless steel (all by Dentaurum). Archwire-guided retraction of a canine was simulated with a force of 0.5 N in the orthodontic measurement and simulation system (OMSS). Friction loss was determined by subtracting the effective orthodontic forces from the applied forces. Based on five repeated measurements performed on five brackets each, weighted means were calculated and evaluated by analysis of variance and a Bonferroni post hoc test with a significance level of 0.05. Friction losses were significantly (p < 0.05) higher (58-79 versus 20-30 %) for the combinations involving the steel versus the resin archwire in conjunction with the elastic ligature. The uncoated steel ligatures were associated with the lowest friction losses with Clarity™ (13 %) and discovery(®) pearl (16 %) on the resin archwire and the highest friction losses with Clarity™ ADVANCED (53 %) and Mystique (63 %) on the steel archwire. The coated steel ligatures were associated with friction losses similar to the uncoated steel

  15. FIBER LENGTH DISTRIBUTION MEASUREMENT FOR LONG GLASS AND CARBON FIBER REINFORCED INJECTION MOLDED THERMOPLASTICS

    SciTech Connect

    Kunc, Vlastimil; Frame, Barbara J; Nguyen, Ba N.; TuckerIII, Charles L.; Velez-Garcia, Gregorio

    2007-01-01

    Procedures for fiber length distribution (FLD) measurement of long fiber reinforced injection molded thermoplastics were refined for glass and carbon fibers. Techniques for sample selection, fiber separation, digitization and length measurement for both fiber types are described in detail. Quantitative FLD results are provided for glass and carbon reinforced polypropylene samples molded with a nominal original fiber length of 12.7 mm (1/2 in.) using equipment optimized for molding short fiber reinforced thermoplastics.

  16. Effect of Cross Sectional Geometry on PDMS Micro Peristaltic Pump Performance: Comparison of SU-8 Replica Molding vs. Micro Injection Molding

    PubMed Central

    Graf, Neil J.

    2013-01-01

    Two different fabrication methods were employed to fabricate micropumps with different cross-sectional channel geometries. The first was to fabricate rectangular cross-sectional microchannel geometries using the well known fabrication method of replica molding (REM).1 The second, and far less utilized fabrication technique, was to create microchannel molds using an in-house fabricated handheld micro injection molding apparatus. The injection mold apparatus was designed for use with elastomeric room temperature vulcanization (RTV) polymers, as opposed to most other injection molding machines, which are designed for use with thermoplastic polymers. The injection mold’s bottom plate was used as a microchannel molding template. The molding template was created by threading a small-diameter wire (150 μm or less) through the injection mold’s bottom plate, with subsequent adhesion and smoothing of a thin piece of aluminum foil over the wire-raised injection mold template. When molded against, the template produced a rounded/Gaussian-shaped PDMS microchannel. The design of the injection mold will be presented, along with a direct comparison for micropump performance metrics such as flow rate, valving characteristics, and maximum backpressures attainable for each of the respective micropump channel geometries. PMID:23917263

  17. 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.

  18. Metal Injection Molding (MIM) of NdFeB Magnets

    NASA Astrophysics Data System (ADS)

    Hartwig, T.; Lopes, L.; Wendhausen, P.; Ünal, N.

    2014-07-01

    Due to the increased and unstable prices for Rare Earth elements there are activities to develop alternative hard magnetic materials. Reducing the amount of material necessary to produce complex sintered NdFeB magnets can also help to reduce some of the supply problem. Metal Injection Molding (MIM) is able to produce near net shape parts and can reduce the amount of finishing to achieve final geometry. Although MIM of NdFeB has been patented and published fairly soon after the development of the NdFeB magnets there has never been an industrial production. This could be due to the fact that MIM was very young at that time and hardly developed. Thus, the feasibility of the process needs to be revaluated. This paper presents results of our work on determining the process parameters influencing the magnetic properties of the sintered magnets as well as the shrinkage during processing. The role of binder and powder loading on the alignment of the particles as well as on the carbon and oxygen contamination was examined.

  19. Injection molding lens metrology using software configurable optical test system

    NASA Astrophysics Data System (ADS)

    Zhan, Cheng; Cheng, Dewen; Wang, Shanshan; Wang, Yongtian

    2016-10-01

    Optical plastic lens produced by injection molding machine possesses numerous advantages of light quality, impact resistance, low cost, etc. The measuring methods in the optical shop are mainly interferometry, profile meter. However, these instruments are not only expensive, but also difficult to alignment. The software configurable optical test system (SCOTS) is based on the geometry of the fringe refection and phase measuring deflectometry method (PMD), which can be used to measure large diameter mirror, aspheric and freeform surface rapidly, robustly, and accurately. In addition to the conventional phase shifting method, we propose another data collection method called as dots matrix projection. We also use the Zernike polynomials to correct the camera distortion. This polynomials fitting mapping distortion method has not only simple operation, but also high conversion precision. We simulate this test system to measure the concave surface using CODE V and MATLAB. The simulation results show that the dots matrix projection method has high accuracy and SCOTS has important significance for on-line detection in optical shop.

  20. Modeling morphology evolution during injection molding of thermoplastic polymers

    NASA Astrophysics Data System (ADS)

    Pantani, R.; De Santis, F.; Speranza, V.; Titomanlio, G.

    2015-05-01

    The effect of temperature, pressure and flow on relaxation time (or spectrum), crystallization time, nucleation density and rate, spherulite growth rate, the interrelation among these quantities and the distributions of deformation rate and cooling time during the process all together determine the morphology distribution in the final object. A simple model linking all these quantities was developed to describe morphology evolution during polymer processing. The effect of flow on nucleation density and growth rate of an isotactic polypropylene (iPP) is described on the basis of a molecular stretch parameter and the stretch evolution is described by a simple nonlinear Maxwell model, whose relaxation time, in its turn, is determined by the molecular stretch and, obviously, temperature pressure and crystallinity [1]. The model is applied to the description of morphology evolution during the injection molding process of a very accurately characterized iPP as far as rheology, quiescent crystallization and effect of flow on nucleation and spherulitic growth rates. Main characteristics of final morphology are reproduced by the simulations.

  1. Injection molded microfluidic devices for biological sample separation and detection

    NASA Astrophysics Data System (ADS)

    Morales, Alfredo M.; Simmons, Blake A.; Wallow, Thomas I.; Campbell, K. Jeffery; Mani, Seethambal S.; Mittal, Brita; Crocker, Robert W.; Cummings, Eric B.; Davalos, Rafael V.; Domeier, Linda A.; Hunter, Marion C.; Krafcik, Karen L.; McGraw, Gregory J.; Mosier, Bruce P.; Sickafoose, Shane M.

    2006-01-01

    We are developing a variety of microsystems for the separation and detection of biological samples. At the heart of these systems, inexpensive polymer microfluidic chips carry out sample preparation and analysis. Fabrication of polymer microfluidic chips involves the creation of a master in etched silicon or glass; plating of the master to produce a nickel stamp; large lot chip replication by injection molding; precision chip sealing; and chemical modification of channel surfaces. Separation chips rely on insulator-based dielectrophoresis for the separation of biological particles. Detection chips carry out capillary electrophoresis to detect fluorescent tags that identify specific biological samples. Since the performance and reliability of these microfluidic chips are very sensitive to fluidic impedance, electromagnetic flux, and zeta potential, the microchannel dimensions, shape, and surface chemistry have to be tightly controlled during chip fabrication and use. This paper will present an overview of chip design, fabrication, and testing. Dimensional metrology data, surface chemistry characterization, and chip performance data will be discussed in detail.

  2. The application of fuzzy theory for the control of weld line positions in injection-molded part.

    PubMed

    Chen, Mei-Yung; Tzeng, Huan-Wen; Chen, Yi-Cheng; Chen, Shia-Chung

    2008-01-01

    This research proposes the fuzzy theory for the control of weld lines in plastic injection molding. The weld line occurs as a result of geometrical changes in molded parts in the injection molding process. The weld line is one of the defects present in plastic injection-molded parts; the line affects the quality of parts as well as the strength of the products. In the present study, fuzzy theory was applied in the design of injection molding. First, expert experiences were transformed into IF approximately THEN approximately rules to establish the knowledge base for developing fuzzy inference rules. The rules were then used to adjust the molding parameters, which in turn were applied to control the weld line position in the injection molding process. The results indicate that fuzzy theory exhibited favorable applicability in the control of the weld line as well as decreased the simulation time, thereby accelerating the design process of injection molding.

  3. Atomic layer deposition as pore diameter adjustment tool for nanoporous aluminum oxide injection molding masks.

    PubMed

    Miikkulainen, Ville; Rasilainen, Tiina; Puukilainen, Esa; Suvanto, Mika; Pakkanen, Tapani A

    2008-05-06

    The wetting properties of polypropylene (PP) surfaces were modified by adjusting the dimensions of the surface nanostructure. The nanostructures were generated by injection molding with nanoporous anodized aluminum oxide (AAO) as the mold insert. Atomic layer deposition (ALD) of molybdenum nitride film was used to control the pore diameters of the AAO inserts. The original 50-nm pore diameter of AAO was adjusted by depositing films of thickness 5, 10, and 15 nm on AAO. Bis(tert-butylimido)-bis(dimethylamido)molybdenum and ammonia were used as precursors in deposition. The resulting pore diameters in the nitride-coated AAO inserts were 40, 30, and 20 nm, respectively. Injection molding of PP was conducted with the coated inserts, as well as with the non-coated insert. Besides the pore diameter, the injection mold temperature was varied with temperatures of 50, 70, and 90 degrees C tested. Water contact angles of PP casts were measured and compared with theoretical contact angles calculated from Wenzel and Cassie-Baxter theories. The highest contact angle, 140 degrees , was observed for PP molded with the AAO mold insert with 30-nm pore diameter. The Cassie-Baxter theory showed better fit than the Wenzel theory to the experimental values. With the optimal AAO mask, the nanofeatures in the molded PP pieces were 100 nm high. In explanation of this finding, it is suggested that some sticking and stretching of the nanofeatures occurs during the molding. Increase in the mold temperature increased the contact angle.

  4. Properties of high density polyethylene – Paulownia wood flour composites via injection molding

    USDA-ARS?s Scientific Manuscript database

    Paulownia wood (PW) flour is evaluated as a bio-based fiber reinforcement. Composites of high density polyethylene (HDPE), 25% by weight of PW, and either 0% or 5% by weight of maleated polyethylene (MAPE) were produced by twin screw compounding followed by injection molding. Molded test composite...

  5. Analysis of cavity pressure and warpage of polyoxymethylene thin walled injection molded parts: Experiments and simulations

    NASA Astrophysics Data System (ADS)

    Guerrier, P.; Tosello, G.; Hattel, J. H.

    2015-05-01

    Process analysis and simulations on molding experiments of 3D thin shell parts have been conducted. Moldings were carried out with polyoxymethylene (POM). The moldings were performed with cavity pressure sensors in order to compare experimental process results with simulations. The warpage was characterized by measuring distances using a tactile coordinate measuring machine (CMM). Molding simulations have been executed taking into account actual processing conditions. Various aspects have been considered in the simulation: machine barrel geometry, injection speed profiles, cavity injection pressure, melt and mold temperatures, material rheological and pvT characterization. Factors investigated for comparisons were: injection pressure profile, short shots length, flow pattern, and warpage. A reliable molding experimental database was obtained, accurate simulations were conducted and a number of conclusions concerning improvements to simulation accuracy are presented regarding: pvT data, mesh, short shots, cavity pressure for process control validation as well as molding machine geometry modelling. Eventually, a methodology for improved molding simulations of cavity injection pressure, filling pattern and warpage was established.

  6. Effect of injection-molding-induced residual stress on microchannel deformation irregularity during thermal bonding

    NASA Astrophysics Data System (ADS)

    Yu, H.; Tor, S. B.; Loh, N. H.; Asundi, A. K.

    2013-01-01

    Micro injection molding offers a promising approach to rapidly produce thermoplastic microfluidic substrates in large volumes. Many research works have been focused on the replication fidelity of microstructures by injection molding. However, there has not been any investigation on the effect of molded-in residual stress on microchannel deformation during the subsequent thermal bonding process. These effects could be important, because the residual stress developed due to anisotropic polymer flow orientation and inhomogeneous cooling may lead to abnormal microchannel distortion. In the direct thermal bonding process, asymmetric cross-sectional distortion was observed in well-formed microchannels aligned perpendicular to the polymer melt injection direction. This asymmetric distortion is attributed to the residual stress introduced into the substrates during molding, particularly in the surface region where microchannels are molded. Design of experiment on injection molding was carried out to reduce the residual stress in order to achieve the lowest microchannel deformation irregularity, which is a new term defined in this study. The direct thermal bonding was utilized as a feasible non-destructive indirectly quantitative method to evaluate the effect of residual stress around microchannel regarding deformation irregularity. The dominant molding parameters with positive effects were found to be melt temperature, mold temperature as well as cooling time after packing. The presence of the residual stress was also demonstrated through photoelastic stress analysis in terms of phase retardation. With improved molding condition, the absolute retardation difference around microchannels aligned parallel and perpendicular to the molding direction could be tuned to the same level, which indicates that the molded-in residual stresses have been moderated.

  7. Comparison of glare in YAG-damaged intraocular lenses: injection-molded versus lathe-cut.

    PubMed

    Bath, P E; Dang, Y; Martin, W H

    1986-11-01

    A comparative analysis of YAG laser intraocular lens (IOL) damage was undertaken on injection-molded and lathe-cut IOLs. Damage sites were evaluated with polarized light. A consistent positive polarization was observed in the damage sites of lathe-cut IOLs. A consistent negative polarization was observed in the damage sites of injection-molded IOLs. The presence of positive polarization in IOL damage sites may be correlated with increased potential for glare. Results and clinical implications are discussed.

  8. Review on Sintering Process of WC-Co Cemented Carbide in Metal Injection Molding Technology

    NASA Astrophysics Data System (ADS)

    Prathabrao, M.; Amin, Sri Yulis M.; Ibrahim, M. H. I.

    2017-01-01

    The objective of this paper is to give an overview on sintering process of WC-Co cemented carbides in metal injection molding technology. Metal injection molding is an advanced and promising technology in producing cemented nanostructured carbides. Cemented tungsten carbide (WC-Co) hard metal is known for its high hardness and wear resistance in various applications. Moreover, areas include fine grained materials, alternative binders, and alternative sintering techniques has been discussed in this paper.

  9. 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.

  10. 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.

  11. Molecular orientation distributions during injection molding of liquid crystalline polymers: Ex situ investigation of partially filled moldings

    SciTech Connect

    Fang, Jun; Burghardt, Wesley R.; Bubeck, Robert A.

    2013-01-10

    The development of molecular orientation in thermotropic liquid crystalline polymers (TLCPs) during injection molding has been investigated using two-dimensional wide-angle X-ray scattering coordinated with numerical computations employing the Larson-Doi polydomain model. Orientation distributions were measured in 'short shot' moldings to characterize structural evolution prior to completion of mold filling, in both thin and thick rectangular plaques. Distinct orientation patterns are observed near the filling front. In particular, strong extension at the melt front results in nearly transverse molecular alignment. Far away from the flow front shear competes with extension to produce complex spatial distributions of orientation. The relative influence of shear is stronger in the thin plaque, producing orientation along the filling direction. Exploiting an analogy between the Larson-Doi model and a fiber orientation model, we test the ability of process simulation tools to predict TLCP orientation distributions during molding. Substantial discrepancies between model predictions and experimental measurements are found near the flow front in partially filled short shots, attributed to the limits of the Hele-Shaw approximation used in the computations. Much of the flow front effect is however 'washed out' by subsequent shear flow as mold filling progresses, leading to improved agreement between experiment and corresponding numerical predictions.

  12. Modular injection mold manufacturing in a selective laser sintering machine

    NASA Astrophysics Data System (ADS)

    Ikonen, Ilkka T.; Biles, William E.

    1997-12-01

    Reduced time to market places exacting requirements for the speed and quality of the design, manufacture and testing of new plastic parts. Traditionally, the greatest time for getting a new plastic product prototyped and tested is that for the mold fabrication phase. New metal materials for selective laser sintering (SLS) rapid prototyping technology allow direct mold fabrication for prototype plastic parts. Typically these molds are also useable for small scale production runs up to 50,000 parts. Using this technology prototype parts can be manufactured using the same materials and processes as used for the final product allowing testing of the whole manufacturing process for the prototype. This gives a company new opportunities to get a new or modified product to market faster and cheaper than by using traditional mold making processes. In this paper we describe this new technology and discuss how small and mid-size manufacturing companies can benefit from it.

  13. Experimental and numerical analysis of the temperature distribution of injection molded products using protruding microprobes.

    PubMed

    Liu, Shih-Jung; Ho, Chia-Wei

    2011-05-01

    Injection molding has been one of the most important polymer processing methods for manufacturing plastic parts. In the process, the temperature is an important parameter that influences process features such as cycle times, crystallization rates, degree of crystallinity, melt flow properties, and molded product qualities. This study aims to, experimentally and numerically, examine the three-dimensional temperature distribution along the melt flow path of injection molded parts. A special experimental set-up, which includes an injection mold equipped with protruding microprobes for guiding embedded thermocouples, was designed and built to measure the temperature field along the flow path, i.e., inside the runner and the cavity, of injection molded products. The experimental results suggested that the disturbance induced by the probes remained negligible and precise temperature profiles could be measured at various positions inside the cavity. A significant increase of melt temperature was found to result from the viscous dissipation of the polymeric materials in the runner. Additionally, a commercially available code was employed to simulate and predict the temperature variation in injection molded parts. It was shown that the numerical simulation predicted better the temperature distributions inside the cavity than those along the runner.

  14. Mechanical and Electrical Properties of Vapor Grown Carbon Fiber/Polypropylene Composites Made by Injection Molding

    NASA Astrophysics Data System (ADS)

    Takahashi, Yoshihiko; Yamagiwa, Yoshitoshi; Kiyono, Ryoutaro; Fujii, Tsuneo

    We made pellets by adding 0-20 wt% vapor grown carbon fiber (VGCF) to polypropylene and made an injection molding test piece with the pellets so as to test the rheological, as well as the mechanical, electrical, and injection molding properties. In the test piece made by injection molding, the quantity of VGCF in the surface layer is extremely small as compared to the quantity of addition. The value of resistance at the end of flow of the injection-molded product is smaller than that measured at other locations, which is considered to be the influence of the fountain flow at the end of flow. In addition, it is known that the above phenomenon is attributable to the fact that the orientation is in the direction of thickness in the same way as the orientation of glass fiber and carbon fiber. Even if the additive rate of VGCF is the same, the value of resistance changes substantially depending on the thickness of injection-molded products. One of the causes is considered to be the orientation of VGCF, and the orientation of VGCF in the test piece is considered to be strong in the direction of flow. There exists a proportionality relation between the shear rate and the value of resistance calculated on the basis of the rate of flow, which is one of the molding conditions.

  15. Experimental and numerical analysis of the temperature distribution of injection molded products using protruding microprobes

    NASA Astrophysics Data System (ADS)

    Liu, Shih-Jung; Ho, Chia-Wei

    2011-05-01

    Injection molding has been one of the most important polymer processing methods for manufacturing plastic parts. In the process, the temperature is an important parameter that influences process features such as cycle times, crystallization rates, degree of crystallinity, melt flow properties, and molded product qualities. This study aims to, experimentally and numerically, examine the three-dimensional temperature distribution along the melt flow path of injection molded parts. A special experimental set-up, which includes an injection mold equipped with protruding microprobes for guiding embedded thermocouples, was designed and built to measure the temperature field along the flow path, i.e., inside the runner and the cavity, of injection molded products. The experimental results suggested that the disturbance induced by the probes remained negligible and precise temperature profiles could be measured at various positions inside the cavity. A significant increase of melt temperature was found to result from the viscous dissipation of the polymeric materials in the runner. Additionally, a commercially available code was employed to simulate and predict the temperature variation in injection molded parts. It was shown that the numerical simulation predicted better the temperature distributions inside the cavity than those along the runner.

  16. Parameter Optimization Of Natural Hydroxyapatite/SS316l Via Metal Injection Molding (MIM)

    NASA Astrophysics Data System (ADS)

    Mustafa, N.; Ibrahim1, M. H. I.; Amin, A. M.; Asmawi, R.

    2017-01-01

    Metal injection molding (MIM) are well known as a worldwide application of powder injection molding (PIM) where as applied the shaping concept and the beneficial of plastic injection molding but develops the applications to various high performance metals and alloys, plus metal matrix composites and ceramics. This study investigates the strength of green part by using stainless steel 316L/ Natural hydroxyapatite composite as a feedstock. Stainless steel 316L (SS316L) was mixed with Natural hydroxyapatite (NHAP) by adding 40 wt. % Low Density Polyethylene and 60 %wt. Palm Stearin as a binder system at 63 wt. % powder loading consist of 90 % wt. of SS316 L and 10 wt. % NHAP prepared thru critical powder volume percentage (CPVC). Taguchi method was functional as a tool in determining the optimum green strength for Metal Injection Molding (MIM) parameters. The green strength was optimized with 4 significant injection parameter such as Injection temperature (A), Mold temperature (B), Pressure (C) and Speed (D) were selected throughout screening process. An orthogonal array of L9 (3)4 was conducted. The optimum injection parameters for highest green strength were established at A1, B2, C0 and D1 and where as calculated based on Signal to Noise Ratio.

  17. Reduction of birefringence in a skin-layer of injection molded polymer strips using CO{sub 2} laser irradiation

    SciTech Connect

    Kurosaki, Yasuo; Satoh, Isao; Saito, Takushi

    1995-12-31

    Injection molding of polymers is currently utilized for numerous industrial applications. Because of high productivity and stable quality of molded products, the injection-molding process makes the production costs lower, and therefore, is expected to spread more widely in the future. This paper deals with a technique for improving the optical quality of injection molded polymer products using radiative heating. The birefringence frozen in a skin-layer of the molded part was reduced by CO{sub 2} laser heating, and the efficiency of this technique was investigated experimentally. Namely, a simple numerical calculation was performed to estimate the heating efficiency of CO{sub 2} laser in the polymer, effects of radiation heating on the skin-layer of the molded polymer were observed by using a mold with transparent windows, and the residual birefringence frozen in the final molded specimen was measured. The results clearly showed that the birefringence in the skin-layer of injection molded polymer strips was reduced with CO{sub 2} laser heating. The authors believe that the proposed method for reducing the birefringence frozen in injection-molded polymer products is suitable for practical molding, because process time required for the injection-molding is only slightly increased with this method.

  18. A Model for Fiber Length Attrition in Injection-Molded Long-Fiber Composites

    SciTech Connect

    TuckerIII, Charles L.; Phelps, Jay H; El-Rahman, Ahmed Abd; Kunc, Vlastimil

    2013-01-01

    Long-fiber thermoplastic (LFT) composites consist of an engineering thermoplastic matrix with glass or carbon reinforcing fibers that are initially 10 to 13 mm long. When an LFT is injection molded, flow during mold filling orients the fibers and degrades the fiber length. Fiber orientation models for injection molding are well developed, and special orientation models for LFTs have been developed. Here we present a detailed quantitative model for fiber length attrition in a flowing fiber suspension. The model tracks a discrete fiber length distribution (FLD) at each spatial node. Key equations are a conservation equation for total fiber length, and a breakage rate equation. The breakage rate is based on buckling of fibers due to hydrodynamic forces, when the fibers are in unfavorable orientations. The FLD model is combined with a mold filling simulation to predict spatial and temporal variations in fiber length distribution in a mold cavity during filling. The predictions compare well to experiments on a glassfiber/ PP LFT molding. Fiber length distributions predicted by the model are easily incorporated into micromechanics models to predict the stress-strain behavior of molded LFT materials. Author to whom correspondence should be addressed; electronic mail: ctucker@illinois.edu 1

  19. Electrical and dielectric properties of foam injection-molded polypropylene/multiwalled carbon nanotube composites

    SciTech Connect

    Ameli, A.; Nofar, M.; Saniei, M.; Hossieny, N.; Park, C. B.; Pötschke, P.

    2015-05-22

    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 in 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.

  20. Electrical and dielectric properties of foam injection-molded polypropylene/multiwalled carbon nanotube composites

    NASA Astrophysics Data System (ADS)

    Ameli, A.; Nofar, M.; Saniei, M.; Hossieny, N.; Park, C. B.; Pötschke, P.

    2015-05-01

    A combination of high dielectric permittivity (ɛ') and low dielectric loss (tan δ) is required for charge storage applications. In percolative systems such as conductive polymer composites, however, obtaining high ɛ' 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 in an injection molding process. Electrical conductivity (σ), ɛ' 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 ɛ'=68.3 and tan δ =0.05 (at 1.25 vol.% MWCNT), as opposed to ɛ'=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.

  1. 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

  2. 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.

  3. Effect of injection molding cycle time on surface properties of polypropylene

    NASA Astrophysics Data System (ADS)

    Kobayashi, Yutaka; Kanai, Toshitaka

    This paper deals with the effect of shortening injection molding cycle time on morphology and properties of the compounded materials of polypropylene (PP), ethylene propylene rubber (EPR) and talc. Recently, shear rate and cooling speed in injection molding for automotive parts have been increasing because of higher productivity. Orientation and crystallinity in the skin layer, which were measured by a polarizing optical microscope and wide angle X-ray diffraction, increased when shortening the cycle time. Phenomenon of bleeding out additives was observed for the evaluation of surface properties by ATR-FTIR. For decreasing resin temperature, higher crystallinity restricted diffusion of additives at the same position in the injection molded plaques. But comparing the gate with the flow end, the difference of bleeding in the position was controlled by the other factors.

  4. Injection molded nanofluidic chips: fabrication method and functional tests using single-molecule DNA experiments.

    PubMed

    Utko, Pawel; Persson, Fredrik; Kristensen, Anders; Larsen, Niels B

    2011-01-21

    We demonstrate that fabrication of well-defined nanofluidic systems can be greatly simplified by injection molding of thermoplastic polymers. Chips featuring nanochannel arrays, microchannels and integrated interconnects are produced in a single processing step by injection molding. The resulting open channel structures are subsequently sealed by facile plasma-enhanced thermal bonding of a polymer film. This fast, inexpensive and industry-compatible method thus provides a single-use all-polymer platform for nanofluidic lab-on-a-chip applications. Its applicability for nanofluidics is demonstrated by DNA stretching experiments performed on individual double-stranded DNA molecules confined in the injection molded nanochannels. The obtained results are consistent with measurements performed in costly state-of-the-art silica nanochannels, for both straight and tapered channel geometries.

  5. Influence of Mold Surface Treatments on Flow of Polymer in Injection Moulding. Application to Weldlines

    NASA Astrophysics Data System (ADS)

    Chailly, M.; Charmeau, J.-Y.; Bereaux, Y.; Monasse, B.

    2007-04-01

    Due to increasing expectations from the market, the aspect of molded parts has to be improved constantly. Some of the defects observed on these parts such as weldlines are related to the filling stage. To limit this, we investigated the influence on weldlines using various surface deposits on the mold surface, mainly PVD and PACVD deposits : Chromium nitride (CrN), Titanium nitride (TiN), Diamond like Carbon (DLC), Chromium and polished steel (PG) on an instrumented plate mold. Injection campaign was led on three polymers which differ in terms of nature (amorphous, semi-crystalline, copolymers). We studied the evolution of the dimensions of weldlines appearing on the plate using the same injection parameters for a given polymer, but with various deposits and thicknesses. Another aspect that had been investigated is the morphology of the weldline through the thickness of the part, depending on polymer nature. Adhesion of polymer at the flow front with the mold surface proved to change. The modification of the initial contact in the filling stage and thus the thermal resistance at the mold implied a change in the process, increasing or reducing the pressure loss in the flow and differential shrinkage in the final part. The induced impact on dimensions of the weldlines allowed to distinguish which surface treatments were able to reduce the defect. A complementary study was led on both polymers in molten state and deposits in terms of wetting using a sessile drop method to confirm the adhesion at the polymer/mold interface. This study proved the influence of the use of surface treatments has clearly an impact on the filling stage of the injection molding process, and it is necessary to get a better knowledge of the interactions between physical adhesion, tribology of polymer/mold contact, and thermal properties of the coatings and their impact on solidification of the polymer.

  6. The shrinkage behavior and surface topographical investigation for micro metal injection molding

    NASA Astrophysics Data System (ADS)

    Islam, A.; Giannekas, N.; Marhöfer, D. M.; Tosello, G.; Hansen, H. N.

    2015-05-01

    Metal injection molding (MIM) is a near net shape manufacturing technology that can produce highly complex and dimensionally stable parts for high end engineering applications. Despite the recent growth and industrial interest, micro metal molding is yet to be the field of extensive research especially when it is compared with micro molding of thermoplastics. The current paper presents a thorough investigation on the process of metal injection molding where it systematically characterizes the effects of important process conditions on the shrinkage and surface quality of molded parts with micro features. Effects of geometrical factors like feature dimensions and distance from the gate on the replication quality are studied. The influence of process conditions on the achievable roughness for the final metal parts is discussed based on the experimental findings. The test geometry is characterized by 2½D surface structures containing thin ribs of different aspect ratios and thicknesses in the sub-mm dimensional range. The test parts were molded from Catamold 316L with a conventional injection molding machine. Afterwards, the parts were de-binded and sintered to produce the final test samples. Among the different process parameters studied, the melt temperature was the most influential parameters for better replication and dimensional stability of the final part. The results presented in the paper clearly show that the shrinkage in metal part is not uniform in the micro scale. It depends on the feature dimensions and also on the process conditions. A thin section of the part exhibits higher relative shrinkage compared with a thicker section. Based on these findings, it can be concluded that a micro part molded by MIM process will have higher relative shrinkage compared to a macro part made with the same process.

  7. 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.

  8. Long-Fiber Thermoplastic Injection Molded Composites: from Process Modeling to Property Prediction

    SciTech Connect

    Nguyen, Ba Nghiep; Holbery, Jim D.; Johnson, Kenneth I.; Smith, Mark T.

    2005-09-01

    Recently, long-fiber filled thermoplastics have become a great interest to the automotive industry since these materials offer much better property performance (e.g. elastic moduli, strength, durability…) than their short-fiber analogues, and they can be processed through injection molding with some specific tool design. However, in order that long-fiber thermoplastic injection molded composites can be used efficiently for automotive applications, there is a tremendous need to develop process and constitutive models as well as computational tools to predict the microstructure of the as-formed composite, and its resulting properties and macroscopic responses from processing to the final product. The microstructure and properties of such a composite are governed by i) flow-induced fiber orientation, ii) fiber breakage during injection molding, and iii) processing conditions (e,g. pressure, mold and melt temperatures, mold geometries, injection speed, etc.). This paper highlights our efforts to address these challenging issues. The work is an integrated part of a research program supported by the US Department of Energy, which includes • The development of process models for long-fiber filled thermoplastics, • The construction of an interface between process modeling and property prediction as well as the development of new constitutive models to perform linear and nonlinear structural analyses, • Experimental characterization of model parameters and verification of the model predictions.

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

    NASA Astrophysics Data System (ADS)

    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® 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.

  10. 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.

  11. An experimental study of yellow shift in injection-molded light guide plate

    NASA Astrophysics Data System (ADS)

    Min, Inki; Lee, Sungjun; Lee, Sunghee; Kim, Jongsun; Yoon, Kyunghwan

    2016-08-01

    Recently, the size of light guide plate (LGP) in LCD-BLU (Backlight Unit) module is getting thinner and larger than ever. The part reached critical thickness to mold it by conventional injection molding methods due to the low flowability, melt solidification, machine limitation, and so on. Therefore, severe conditions have been applied to the part to increase the flowability such as high injection speeds and higher melt temperature. However, these approaches lead to the degradation of material and loss of optical properties. These defects are connected to the invisible part failure, so called, yellowing and color shift. In the present study a series of injection molding experiments were conducted to understand the distribution of yellowness in injection-molded LGP, and how the optical properties change under various injection molding conditions. Optical properties of yellow index (YI), CIE xy, and spectral transmittances of LGP sample were analyzed by the UV-visible spectrophotometer. Also, correlations between optical properties and process conditions were investigated from the Design of experiment (DOE). Interestingly, the value of YI, i.e., yellow shift in CIE diagram showed the maximum near the gate and decreased as the distance from the gate increased. Furthermore, as far as yellow shift concerned the data of direct transmittance are much more useful than total transmittance for evaluating color behavior. Meanwhile, analysis of variance (ANOVA) was conducted to see the effectiveness of chosen processing parameters. Mold temperature was found to be the most influential factor on the color shift and injection speed, melt temperature, packing pressure were followed.

  12. Flow-induced birefringence: the hidden PSF killer in high performance injection-molded plastic optics

    NASA Astrophysics Data System (ADS)

    Chidley, Matthew D.; Tkaczyk, Tomasz; Kester, Robert; Descour, Michael R.

    2006-02-01

    A 7-mm OD, NA = 1 water immersion injection-molded plastic endoscope objective has been fabricated for a laser scanning fiber confocal reflectance microscope (FCRM) system specifically designed for in vivo detection of cervical and oral pre-cancers. Injection-molded optics was selected for the ability to incorporate aspheric surfaces into the optical design and its high volume capabilities. Our goal is high performance disposable endoscope probes. This objective has been built and tested as a stand-alone optical system, a Strehl ratio greater than 0.6 has been obtained. One of the limiting factors of optical performance is believed to be flow-induced birefringence. We have investigated different configurations for birefringence visualization and believe the circular polariscope is most useful for inspection of injection-molded plastic optics. In an effort to decrease birefringence effects, two experiments were conducted. They included: (1) annealing of the optics after fabrication and (2) modifying the injection molding prameters (packing pressures, injection rates, and hold time). While the second technique showed improvement, the annealing process could not improve quality without physically warping the lenses. Therefore, to effectively reduce flow-induced birefringence, molding conditions have to be carefully selected. These parameters are strongly connected to the physical part geometry. Both optical design and fabrication technology have to be considered together to deliver low birefringence while maintaining the required manufacturing tolerances. In this paper we present some of our current results that illustrate how flow-induced birefringence can degrade high performance injection-molded plastic optical systems.

  13. Injection Molding of Sinterable Silicon-Base, Nonoxide Ceramics.

    DTIC Science & Technology

    1978-12-01

    Batch 116-25 14 As-Injected Stator Vane and Test Bars 30 15 Test Bar Tool in Position in Arburg Injection 32 Machine 16 Cold Pressed Green Density vs...Injection Machine: Arburg 221E-150 Part Injected: TPE331-C turbine second stage stator vane and two associated MOR test bars Machine Settings: Feed...optimum machine settings for the test bar tool on the Arburg 221E-150 are shown in Table 8. TABLE 8 OPTIMUM MACHINE SETTINGS FOR TEST BAR INJECTION Feed

  14. Influence of Injection Molding Process on the Local Fluctuations of Magneto-Optical Signals

    NASA Astrophysics Data System (ADS)

    Umezawa, Tomokazu; Horiguchi, Toru; Tomie, Takashi

    2001-01-01

    The local fluctuations of magneto-optical (MO) signals were investigated in the vicinity of the preformat pits of polycarbonate (PC) substrates fabricated under different injection molding conditions and also using stampers which had different shapes of grooves and preformat pits. A strong correlation was observed between the substrate birefringence and the fluctuation of the MO signal. The rate-of-change of the fluctuations, as the phase shift of the optical head was varied, was attributed to the shapes of preformat pits and grooves. The fluctuation of the MO signal could be controlled by varying the injection molding conditions and the shapes of preformat pits and grooves.

  15. 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

  16. 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.

  17. Surface topographic characterization for polyamide composite injection molds made of aluminum and copper alloys.

    PubMed

    Pereira, A; Hernández, P; Martinez, J; Pérez, J A; Mathia, T G

    2014-01-01

    In order to ensure flexibility and rapid new product development, the mold industry made use of soft materials for cavity inserts in injection molds. However, materials of this kind are prone to wear. This article analyzes the topographic characterization of the surface and wear processes in injection molds cavities. Two materials have been used to produce the cavities: aluminum alloy EN AW‐6082 T4 and copper alloy Cu Zn39 Pb3. The surface topography was measured with the use of optical interferometry profiling technology; roughness and surface parameters were determined according to ISO 4287, ISO 25178, and EUR 15178N. In order to complete this research, an experimental part with different thicknesses and shapes was designed, and cavity inserts of aluminum and copper were made. Polyamide PA6, with 30% fiberglass reinforcement, was employed in the experimental procedure. Measurements of cavity mold surfaces were performed after 9,200 cycles on each mold and at different locations on the mold. The surface measurement was made with a white light vertical scanning interferometry, also known as coherence scanning interferometry (ISO DIS 25178‐604). The results are analyzed and differences between the two types of cavity inserts materials are discussed.

  18. Mechanical properties depending on fiber orientation in injection molded short-fiber-reinforced plastic parts

    SciTech Connect

    Chung, S.T.; Kwon, T.H.

    1996-12-31

    In injection molding of short-fiber-reinforced plastics, the fiber orientation during a mold filling process is determined by the flow field, while it is in turn affected by the orientation state of fibers. The Dinh and Armstrong`s orientation-dependent constitutive equation for fiber suspension was thus incorporated into the coupled analysis of mold filling flow and fiber orientation including the additional stresses due to the existence of fibers. The mold filling simulation was then performed by solving a new pressure equation and the energy equation via a finite element/finite difference method as well as evolution equations for the second-order orientation tensor via the fourth-order Runge-Kutta method. With the fiber orientation known, predictions of the anisotropic mechanical properties of the composites are obtained by using the Halpin-Tsai equations for unidirectional composites and taking an orientation average.

  19. 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.

  20. 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.

  1. Adhesion strength between thermoplastics and its polyurethane coating made by using the technology combination of injection molding and reaction injection molding

    NASA Astrophysics Data System (ADS)

    Bloß, P.; Böhme, A.; Müller, J.; Krajewsky, P.; Michaelis, J.

    2014-05-01

    A complete equipment for injection molding (IM) of a thermoplastic (TP) carrier and reaction injection molding (RIM) of polyurethane (PUR) coatings including IM and RIM machines, a color module for PUR, and a robot was built up. A modularly composed sliding split mold was constructed and manufactured allowing different parts including thicker (2 mm thickness) soft touch and thin (0.4 mm) lacquer PUR coatings. As TP PC/ABS and PA6 GF15 compounds were used, and aromatic and aliphatic PUR systems as well. From the parts made by IM+RIM, test specimens for peel force measurements were cut. These investigations were performed prior and after ageing under climatic conditions @ 50 % RH and temperature changes between -30 °C and 90 °C. By varying IM processing parameters, we have found that mold and TP temperatures are particularly important for the adhesion strength between TP and PUR. The waiting time between the end of TP cooling and PUR injection has a minor influence on its mean value. However, to short waiting times may result in inhomogeneous adhesion. It was surprising that surface defects of the TP carrier leads also to inhomogeneous adhesion. We have observed that ageing may cause an increase and decrease of adhesions strength depending on the TP+PUR system used. We have found that the results are valid only for the actual TP and PUR combination. A generalization seems to be inappropriate, hence, the actual combination should be investigated to prevent unwanted surprises when the coated TP part is in its application.

  2. Production and evaluation of measuring equipment for share viscosity of polymer melts included nanofiller with injection molding machine

    NASA Astrophysics Data System (ADS)

    Kameda, Takao; Sugino, Naoto; Takei, Satoshi

    2016-10-01

    Shear viscosity measurement device was produced to evaluate the injection molding workability for high-performance resins. Observation was possible in shear rate from 10 to 10000 [1/sec] that were higher than rotary rheometer by measuring with a plasticization cylinder of the injection molding machine. The result of measurements extrapolated result of a measurement of the rotary rheometer.

  3. Validation of New Process Models for Large Injection-Molded Long-Fiber Thermoplastic Composite Structures

    SciTech Connect

    Nguyen, Ba Nghiep; Jin, Xiaoshi; Wang, Jin; Kunc, Vlastimil; Tucker III, Charles L.

    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 Oak 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.

  4. DAMAGE MODELING OF INJECTION-MOLDED SHORT- AND LONG-FIBER THERMOPLASTICS

    SciTech Connect

    Nguyen, Ba Nghiep; Kunc, Vlastimil; Bapanapalli, Satish K.; Phelps, Jay; Tucker III, Charles L.

    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 been 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.

  5. 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

  6. 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.

  7. Resin Flow Analysis in the Injection Cycle of a Resin Transfer Molded Radome

    NASA Astrophysics Data System (ADS)

    Golestanian, Hossein; Poursina, Mehrdad

    2007-04-01

    Resin flow analysis in the injection cycle of an RTM process was investigated. Fiberglass and carbon fiber mats were used as reinforcements with EPON 826 epoxy resin. Numerical models were developed in ANSYS finite element software to simulate resin flow behavior into a mold of conical shape. Resin flow into the woven fiber mats is modeled as flow through porous media. The injection time for fiberglass/epoxy composite is found to be 4407 seconds. Required injection time for the carbon/epoxy composite is 27022 seconds. Higher injection time for carbon/epoxy part is due to lower permeability value of the carbon fibers compared to glass fiber mat.

  8. Influence of the local morphology on the surface tension of injection molded polypropylene

    NASA Astrophysics Data System (ADS)

    Gomes, M.; Pontes, A. J.; Viana, J. C.

    2014-05-01

    In this work, we investigate the development of the morphology of an injection molding polypropylene under the local thermomechanical environment imposed during processing, and its effect on the contact angle and, hence, on the surface tension of the moldings. Melt and mold temperatures were varied in two levels. The local thermomechanical environment was characterized by mold filling computational simulations that allow the calculation of thermomechanical variables (e.g., local temperatures, shear stresses) and indices (related to the local morphology development). In order to investigate the structural hierarchy variations of the moldings in the thickness direction, samples from skin to core were used. The molecular orientation and degree of crystallinity were determined as function of the thickness, as well as the contact angle. The variations of the degree of crystallinity were assessed by differential scanning calorimetry. The level of molecular orientation was evaluated by birefringence measurements. The contact angles were measured in deionized water by sessile drop (needle in) method at room temperature, to determine the wettability of the samples. The contact angles were found to vary along the molding thickness in the skin, transition and core layers. These variations are related to the local morphologies developed. Results suggest that water contact angle increases with the level of molecular orientation and for finer microstructures.

  9. Effects of adding injection-compression to rapid heat cycle molding on the structure of a light guide plate

    NASA Astrophysics Data System (ADS)

    Hong, Seokkwan; Min, Inki; Yoon, Kyunghwan; Kang, Jeongjin

    2014-01-01

    This study investigates the effects of adding injection-compression to rapid heat cycle molding (RHCM) (rapid heat cycle injection-compression molding (RICM)) on the physical quality and optical anisotropy of a molded light guide plate (LGP). Transcription ratio of microstructure, uniformity of part thickness and birefringence were experimentally evaluated on a 7 inch LGP of nominal thickness of 1.12 mm (including a microstructure array of 30 µm diameter and 14 µm height). The designed mold was equipped with rapid heating and compressing facilities and a microstructured nickel stamper was fabricated by UV LIGA process. In addition, to investigate the efficacy of RICM, experiments involving conventional injection molding (CIM), ICM, and RHCM were conducted in parallel with RICM using the same mold. RHCM and RICM yielded excellent transcription ratios for the microstructure, while CIM and RICM provided high thickness uniformity and low birefringence. Thus, RICM obtains high transcription ratio of microstructure, uniform thickness and low birefringence.

  10. A Study of Micro Injection Molding for High-Aspect-Ratio Optical Fiber Ferrules

    NASA Astrophysics Data System (ADS)

    Lin, Zheng-Guan.; Tseng, Shi-Chang; Wang, James; Su, Yi-Chung

    2004-06-01

    This study focused on manufacture of high-aspect-ratio optical fiber ferrules by micro thermoplastic injection molding technique. In the past, the optical fiber connectors were produced by ceramic powder injection molding and subsequent precision grinding process. In this work, plastic micro injection molding technique was attempted to manufacture net-shaped products at once. Each ferrule has a micro through hole in the center. The hole's diameter is 125±1μm, and its length is 9mm. During micro molding, how to keep the micro core pin at the center becomes a critical issue. In this work, a guiding slide system is introduced to hold the micro pin continuously. And the slide movement was controlled by a spring behind it. Such a guiding system can help reduce mis-alignment of the micro core pin and increase its life time. Taguchi's design of experiment was used to evaluate the effects of processing parameters on final properties. Experimental results reveal that the higher the spring force, the larger the product weight and the lower the shrinkage. In order to obtain better uniformity of diameters at different locations, diameters at three locations were measured. Measured data showed the shrinkage of diameter in the middle is greater than those at two ends. It is because the two ends cooled faster than the center region. This can be improved by applying higher mold temperature or appropriate holding pressure or holding time. The new design concept can be applied in molding micro tubes, especially for the high aspect ratio cases.

  11. Progress in modeling long glass and carbon fiber breakage during injection molding

    NASA Astrophysics Data System (ADS)

    Chen, Hongyu; Cieslinski, Mark; Baird, Donald G.

    2015-05-01

    This work is concerned with the modeling of in-machine fiber breakage during injection molding. A lab-scale single screw extruder is used to evaluate fiber breakage in the screw. Our experiments show that as the initial glass fiber pellets length is reduced relative to the channel width, the overall percent of breakage is reduced. We believe that the ratio of initial pellet length to the screw channel width, or diameter, is an important parameter determining the percent of fiber breakage. Data have been fit using an exponential decay model with a kinetic decay constant and a critical length value. This empirical model has been tested on an injection molding machine with a screw 1.6 times larger than that of our single screw extruder. The predicted average fiber length leaving the nozzle shows reasonable agreement with the measured value. For the injection molded end-gated-plaque produced by the same machine, additional fiber breakage has been observed in the runner. A hydrodynamic force based breakage model is combined with mold filling simulation to simulate the fiber breakage in the runner. For carbon fibers, similar breakage trends were observed in the single screw extruder indicating the applicability of our empirical model to carbon fiber.

  12. 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.

  13. Surface Orientation in Injection-Molded Thermotropic Liquid Crystalline Copolyester (TLCP) Plaques

    NASA Astrophysics Data System (ADS)

    Bubeck, Robert; Fang, Jun; Burghardt, Wesley; Burgard, Susan; Robertson, Katherine; Fischer, Daniel

    2008-03-01

    Attenuated total reflection Fourier transform infra-red (ATR-FTIR), C K edge near edge X-ray adsorption fine structure (NEXAFS) spectroscopies, and 2-D WAXS in transmission were used to characterize surface orientation in thermotropic liquid crystalline copolyester (TLCP) injection-molded plaques to varying depths into the samples. Injection-molded TLCPs have bimodal orientation states due to contributions from ``skin'' and ``core'' regions resulting from extensional and shear flow, respectively, in the mold. The NEXAFS is sensitive to the orientation of the molecular pi orbital of backbone phenyl groups of the top 2 nm of a surface. ATR-FTIR obtained using a Herrick Seagull variable angle reflectance accessory is sensitive for dichroic ratios to a depth of 5 microns. Orientation parameters derived from the 1502/cm absorption band for equivalent positions are often typically about 5 to 10 percent less by ATR-FTIR than by NEXAFS. The orientational states are being correlated with physical properties of injection-molded TLCP samples.

  14. A review of contamination related hydraulic pump problems in Japanese injection molding, extrusion and rubber molding industries

    SciTech Connect

    Sasaki, Akira

    1997-12-31

    It is known that contamination of hydraulic oil is one of the major factors causing hydraulic pump problems. Many test reports on contaminant sensibility of hydraulic pumps have been published with new oil and standard dusts but the results of these tests could not guarantee to predict in-service performance. This report describes three cases investigated. The first investigation was done on hydraulic pumps used for injection molding machines application. The causes of pump problems were examined by analysis of maintenance records. The second investigation was performed to determine overhaul frequency of hydraulic pumps used for aluminum extruders. By introducing a new method of hydraulic oil management which reduces oil oxidation products, pump life was extended from 3,000 to 15,000 hours. The third investigation was done to determine the relationship between pump problems and contamination levels of hydraulic oils of 411 rubber molding machines for 20 months. The results showed that pump problems appeared at half the recommended oil lifetimes for these fluids. These studies showed that the cause of pump problems was clogging of suction strainers leading to pump cavitation. The clogged strainers were washed with several different solvents to identify the causes of suction strainer clogging. Clogging of suction strainers was attributable to sticky oxidation products of hydraulic oils. Electrostatic oil cleaners removed not only micron range solid particles bu also submicron size particles. Hydraulic pump problems have been substantially reduced by introducing this new method of contamination control.

  15. Curved hierarchically micro-micro structured polypropylene surfaces by injection molding

    NASA Astrophysics Data System (ADS)

    Mielonen, K.; Suvanto, M.; Pakkanen, T. A.

    2017-01-01

    Structural hierarchy of polymer surfaces has been of central interest due to its diverse surface functionalities. However, the research on hierarchically structured polymer surfaces has been focused on planar surfaces even though applications may also be variously curved. This study demonstrates the fabrication of curved rigid polymer surfaces with precisely controlled hierarchical microstructures. The surface structuration was made on an aluminum foil with a microworking robot, and polypropylene replicas were produced by injection molding. Depending on the mold structuration procedure, the curved mold can have either radially or vertically oriented structures. Both convex and concave curvatures were here applied to spherically and cylindrically curved surfaces. A simple structure protection technique was applied to support the structures during mechanical bending of the foil. The planar hierarchically microstructured polypropylene surfaces were characterized to exhibit superhydrophobicity, and similar structures were obtained on the curved surfaces. Introducing the curvature to the hierarchically structured surfaces may further widen the applicability of functionalized polymer surfaces.

  16. Modeling of the flow continuum and optimal design of control-oriented injection systems in liquid composite molding processes

    NASA Astrophysics Data System (ADS)

    Gokce, Ali

    Several methodologies are presented in this dissertation that aim to ensure successful filling of the mold cavity consistently, during the mold filling stage of Liquid Composite Molding (LCM) processes such as Resin Transfer Molding (RTM), Vacuum Assisted Resin Transfer Molding (VARTM) and Seemann Composites Resin Infusion Molding (SCRIMP). Key parameters that affect the resin flow in the mold cavity can be divided into two main groups as continuum-related parameters and injection-related parameters. Flow continuum, which consists of all the spaces resin can reach in the mold cavity, has two major components: the porous medium, which is made up of the fiber reinforcements, and the flow channels that are introduced into the flow continuum unintentionally and offer an easy flow path to the resin. The properties that characterize the porous medium and the unintentional flow channels are continuum-related parameters. The injection-related parameters include resin injection locations (gates), resin injection conditions and air drainage locations (vents). Modeling the flow continuum is crucial in predicting the resin flow in the mold cavity. In this study, permeability, the key property of the porous medium, is predicted using the Method of Cells, a proven method to predict macroscopic properties of heterogeneous materials. Unintentional flow channels, which are also called racetracking channels, are modeled using a probabilistic approach. Injection-related parameters are the key tools to influence the resin flow in the mold cavity. In this study, Branch and Bound Search is modified for single gate optimization. Due to its pertinence to injection system design, the parameters that govern gate effectiveness in steering the resin advance are studied. A combinatorial search algorithm is proposed for vent optimization. Vent optimization and gate optimization algorithms are integrated for simultaneous gate and vent optimization. Overall, these methodologies reduce the cycle

  17. Investigation of injection molding of orthogonal fluidic connector for microfluidic devices

    NASA Astrophysics Data System (ADS)

    Xu, Zheng; Cao, Dong; Zhao, Wei; Song, Man-cang; Liu, Jun-shan

    2017-02-01

    Orthogonal fluidic connections are essential for developing multilayered microfluidic devices. At present, most orthogonal connectors are realized by a horizontal channel and a vertical channel in different plates. Therefore, some extra alignment and adhesion processes for precise plate assembly are required. In this paper, the method of injection molding is proposed to make a one-body-type orthogonal connector in a single plastic plate. The connector was composed of a cantilevered tube and the other in the substrate. An injection mold was developed in which a side core-pulling mechanism and an ejection mechanism of push-pipes were combined to form the mold for an orthogonal connector. Both the type and the location of gate were optimized for the mold. The results showed that the fan gate in the middle position of the plate was the most suitable in term of both defect control and practicability. The effect of melt temperature was numerically investigated and then verified experimentally. With the optimized parameters, the relative length and the relative wall thickness of a cantilevered tube in the plastic part can reach 98.89% and 99.80%, respectively. Furthermore, using the plastic part as a cover plate, a three-layer plastic microfluidic device was conveniently fabricated for electrochemical detection.

  18. Fabrication of tissue engineered tympanic membrane patches using computer-aided design and injection molding.

    PubMed

    Hott, Morgan E; Megerian, Cliff A; Beane, Rich; Bonassar, Lawrence J

    2004-07-01

    The goal of the current study was to use computer-aided design and injection molding technologies to tissue engineer precisely shaped cartilage in the shape of butterfly tympanic membrane patches out of chondrocyte-seeded calcium alginate gels. Molds were designed on SolidWorks 2000 and built out of acrylonitrile butadiene styrene (ABS) using fused deposition modeling (FDM). Tympanic membrane patches were fabricated using bovine articular chondrocytes seeded at 50 x 10 cells/mL in 2% calcium alginate gels. Molded patches were cultured in vitro for up to 10 weeks and assessed biochemically, morphologically, and histologically. Unmolded patches demonstrated outstanding dimensional fidelity, with a volumetric precision of at least 3 microL, and maintained their shape well for up to 10 weeks of in vitro culture. Glycosaminoglycan and collagen content increased steadily over 10 weeks in culture, demonstrating continual deposition of new extracellular matrix consistent with new tissue development. The use of computer-aided design and injection molding technologies allows for the fabrication of very small, precisely shaped chondrocyte-seeded calcium alginate structures that faithfully maintain their shape during in vitro culture. In vitro fabrication of tympanic membrane patches with a precisely controlled geometry may have the potential to provide a minimally invasive alternative to traditional methods for the repair of chronic tympanic membrane perforations.

  19. 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.

  20. Local mechanical properties of LFT injection molded parts: Numerical simulations versus experiments

    NASA Astrophysics Data System (ADS)

    Desplentere, F.; Soete, K.; Bonte, H.; Debrabandere, E.

    2014-05-01

    In predictive engineering for polymer processes, the proper prediction of material microstructure from known processing conditions and constituent material properties is a critical step forward properly predicting bulk properties in the finished composite. Operating within the context of long-fiber thermoplastics (LFT, length < 15mm) this investigation concentrates on the prediction of the local mechanical properties of an injection molded part. To realize this, the Autodesk Simulation Moldflow Insight 2014 software has been used. In this software, a fiber breakage algorithm for the polymer flow inside the mold is available. Using well known micro mechanic formulas allow to combine the local fiber length with the local orientation into local mechanical properties. Different experiments were performed using a commercially available glass fiber filled compound to compare the measured data with the numerical simulation results. In this investigation, tensile tests and 3 point bending tests are considered. To characterize the fiber length distribution of the polymer melt entering the mold (necessary for the numerical simulations), air shots were performed. For those air shots, similar homogenization conditions were used as during the injection molding tests. The fiber length distribution is characterized using automated optical method on samples for which the matrix material is burned away. Using the appropriate settings for the different experiments, good predictions of the local mechanical properties are obtained.

  1. Conformal cooling and rapid thermal cycling in injection molding with 3D printed tools

    NASA Astrophysics Data System (ADS)

    Xu, Xiaorong

    Solid Freeform Fabrication processes such as 3D Printing have demonstrated the potential to produce tools with complex internal geometry. This work explores the application of this capability to improved thermal management for injection molding tooling through: (i)cooling lines which are conformal to the mold surface which provide improved uniformity and stability of mold temperature and (ii)tools with low thermal inertia which, in combination with conformal fluid channels allow for rapid heating and cooling of tooling, thereby facilitating isothermal filling of the mold cavity. This work presents a systematic, modular, approach to the design of conformal cooling channels. Recognizing that the cooling is local to the surface of the tool, the tool is divided up into geometric regions and a channel system is designed for each region. Each channel system is itself modeled as composed of cooling elements, typically the region spanned by two channels. Six criteria are applied including; a transient heat transfer condition which dictates a maximum distance from mold surface to cooling channel, considerations of pressure and temperature drop along the flow channel and considerations of strength of the mold. These criteria are treated as constraints and successful designs are sought which define windows bounded by these constraints. The methodology is demonstrated in application to a complex core and cavity for injection molding. In the area of rapid thermal cycling, this work utilizes the design methods for conformal channels for the heating phases and adds analysis of the packing and cooling phases. A design is created which provides thermal isolation and accommodation of cyclic thermal stresses though an array of bendable support columns which support the molding portion of the tool where the heating/cooling channels are contained. Designed elasticity of the tool is used to aid in packing of the polymer during the cooling phase. Methodology for the design of this

  2. Influence of water sorption on mechanical properties of injection-molded thermoplastic denture base resins.

    PubMed

    Hamanaka, Ippei; Iwamoto, Misa; Lassila, Lippo; Vallittu, Pekka; Shimizu, Hiroshi; Takahashi, Yutaka

    2014-11-01

    This study investigated the influence of water sorption on certain mechanical properties of injection-molded thermoplastic denture base resins. Six thermoplastic resins (two polyamides, two polyesters, one polycarbonate, one polymethylmethacrylate) and a polymethylmethacrylate (PMMA) conventional heat-polymerized denture-based polymer, selected as a control, were tested. Specimens of each denture base material were fabricated according to ISO 1567 specifications and were either dry or water-immersed for 30 days (n = 10). The ultimate flexural strength, the flexural strength at the proportional limit and the elastic modulus of the denture base materials were calculated. Water sorption significantly decreased the ultimate flexural strength, the flexural strength at the proportional limit and the elastic modulus of one of the polyamides and the PMMAs. It also significantly increased the ultimate flexural strength of the polycarbonate. The mechanical properties of some injection-molded thermoplastic denture base resins changed after water sorption.

  3. Inexpensive 3dB coupler for POF communication by injection-molding production

    NASA Astrophysics Data System (ADS)

    Haupt, M.; Fischer, U. H. P.

    2011-01-01

    POFs (polymer optical fibers) gradually replace traditional communication media such as copper and glass within short distance communication systems. Primarily, this is due to their cost-effectiveness and easy handling. POFs are used in various fields of optical communication, e.g. the automotive sector or in-house communication. So far, however, only a few key components for a POF communication network are available. Even basic components, such as splices and couplers, are fabricated manually. Therefore, these circumstances result in high costs and fluctuations in components' performance. Available couplers have high insertion losses due to their manufacturing method. This can only be compensated by higher power budgets. In order to produce couplers with higher performances new fabrication methods are indispensable. A cheap and effective way to produce couplers for POF communication systems is injection molding. The paper gives an overview of couplers available on market, compares their performances, and shows a way to produce couplers by means of injection molding.

  4. From Process Modeling to Elastic Property Prediction for Long-Fiber Injection-Molded Thermoplastics

    SciTech Connect

    Nguyen, Ba Nghiep; Kunc, Vlastimil; Frame, Barbara J.; Phelps, Jay; Tucker III, Charles L.; Bapanapalli, Satish K.; Holbery, James D.; Smith, Mark T.

    2007-09-13

    This paper presents an experimental-modeling approach to predict the elastic properties of long-fiber injection-molded thermoplastics (LFTs). The approach accounts for fiber length and orientation distributions in LFTs. LFT samples were injection-molded for the study, and fiber length and orientation distributions were measured at different locations for use in the computation of the composite properties. The current fiber orientation model was assessed to determine its capability to predict fiber orientation in LFTs. Predicted fiber orientations for the studied LFT samples were also used in the calculation of the elastic properties of these samples, and the predicted overall moduli were then compared with the experimental results. The elastic property prediction was based on the Eshelby-Mori-Tanaka method combined with the orientation averaging technique. The predictions reasonably agree with the experimental LFT data

  5. The development of an injection-molding process for a polyanhydride implant containing gentamicin sulfate.

    PubMed

    Deng, Jone-Shin; Meisters, Marts; Li, Luk; Setesak, Jeff; Claycomb, Lee; Tian, Youqin; Stephens, Dennis; Widman, Matt

    2002-01-01

    A production-scale manufacturing process has been developed for polyanhydride/gentamicin sulfate implants for the treatment of osteomyelitis. Gentamicin sulfate was first dried to an acceptable moisture level by using a tumble vacuum dryer. Dried gentamicin sulfate powder and polyanhydride granules were separately fed into the twin-screw extruder at a pre-determined metering rate using a gravimetric feeding device. The extruded molten mixture was solidified to form strands which were subsequently cut into pellets by using a pelletizer. The pellets were characterized with respect to copolymer molecular weight and drug content uniformity. The pellets were later fed into production-scale injection-molding equipment for implant fabrication. The injection-molding cycle was developed and evaluated in terms of cycle reproducibility. Implants were tested and shown to yield an oriented skin-core structure exhibiting a desirable in-vitro drug release profile.

  6. Monitoring of binder removal from injection molded ceramics using air-coupled ultrasound at high temperature.

    PubMed

    Wright, W D; Hutchins, D A

    1999-01-01

    A pair of capacitance-type air-coupled ultrasonic transducers have been constructed that were capable of operating in air at temperatures of 500 to 600 degrees C. These devices were then used to monitor the pyrolytic removal of organic binder from injection molded silicon nitride ceramic components using air-coupled ultrasound inside a furnace at elevated temperatures. Through-thickness waveforms were obtained in the ceramic and compared with simultaneous measurements of the mass of the sample. Both the ultrasonic velocity and signal amplitudes could be used to monitor the change in mass of the injection molded ceramic, and other phenomena (such as softening and redistribution of the binder) were observed.

  7. 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.

  8. Structural Reorganization of CNC in Injection-Molded CNC/PBAT Materials under Thermal Annealing.

    PubMed

    Mariano, Marcos; El Kissi, Nadia; Dufresne, Alain

    2016-10-04

    Composite materials were prepared by extrusion and injection molding from polybutyrate adipate terephthalate (PBAT) and high aspect ratio cellulose nanocrystals (CNCs) extracted from capim dourado fibers. Three CNC contents were used, corresponding to 0.5, 1, and 2 times the theoretical percolation threshold. Small-amplitude oscillary shear (SAOS) experiments show that as the CNC content increases, a more elastic behavior is observed but no percolating network can form within the polymeric matrix as a result of the high shear rates involved during the injection-molding process. Annealing of the samples at 170 °C was performed, and the possible reorganization of the nanofiller was investigated. This reorganization was further elucidated using 2D-SAOS and creep experiments.

  9. Optimization and evaluation of metal injection molding by using X-ray tomography

    SciTech Connect

    Yang, Shidi; Zhang, Ruijie; Qu, Xuanhui

    2015-06-15

    6061 aluminum alloy and 316L stainless steel green bodies were obtained by using different injection parameters (injection pressure, speed and temperature). After injection process, the green bodies were scanned by X-ray tomography. The projection and reconstruction images show the different kinds of defects obtained by the improper injection parameters. Then, 3D rendering of the Al alloy green bodies was used to demonstrate the spatial morphology characteristics of the serious defects. Based on the scanned and calculated results, it is convenient to obtain the proper injection parameters for the Al alloy. Then, reasons of the defect formation were discussed. During mold filling, the serious defects mainly formed in the case of low injection temperature and high injection speed. According to the gray value distribution of projection image, a threshold gray value was obtained to evaluate whether the quality of green body can meet the desired standard. The proper injection parameters of 316L stainless steel can be obtained efficiently by using the method of analyzing the Al alloy injection. - Highlights: • Different types of defects in green bodies were scanned by using X-ray tomography. • Reasons of the defect formation were discussed. • Optimization of the injection parameters can be simplified greatly by the way of X-ray tomography. • Evaluation standard of the injection process can be obtained by using the gray value distribution of projection image.

  10. Bond strength of a chairside autopolymerizing reline resin to injection-molded thermoplastic denture base resins.

    PubMed

    Hamanaka, Ippei; Shimizu, Hiroshi; Takahashi, Yutaka

    2017-01-01

    This study evaluated the shear bond strength of a chairside autopolymerizing reline resin to injection-molded thermoplastic denture base resins. Four kinds of injection-molded thermoplastic resins (two polyamides, a polyethylene terephthalate copolymer and a polycarbonate) and PMMA, as a control, were tested. The eight types of surface treatment: ((1) no treatment, (2) air abrasion, (3) dichloromethane, (4) ethyl acetate, (5) 4-META/MMA-TBB resin, (6) air abrasion and 4-META/MMA-TBB resin, (7) tribochemical silica coating, and (8) tribochemical silica coating and 4-META/MMA-TBB resin) were applied to each specimen. The chairside autopolymerizing reline resins were bonded to disks of the injection-molded thermoplastic denture base resins. All of the specimens were immersed in water for 4 months and then thermocycled for 10,000 cycles in water between 5 and 55°C. The shear bond strengths were determined. The shear bond strengths of the two polyamides treated using air abrasion, dichloromethane and ethyl acetate and no treatment were exceedingly low. The greatest bond strength was recorded for the polyethylene terephthalate copolymer specimens treated with tribochemical silica coating and 4-META/MMA-TBB resin (22.5MPa). The bond strengths of the other injection-molded thermoplastic denture base resins increased using 4-META/MMA-TBB resin. Tribochemical silica coating and 4-META/MMA-TBB resin were the most effective surface treatments among all denture base resins tested. Copyright © 2016 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

  11. Effect of boron compounds on physical, mechanical, and fire properties of injection molded wood plastic composites

    Treesearch

    Nadir Ayrilmis; Turgay Akbulut; Turker Dundar; Robert H. White; Fatih Mengeloglu; Zeki Candan; Umit Buyuksari; Erkan Avci

    2011-01-01

    Physical, mechanical, and fire properties of the injection-molded wood flour/polypropylene composites (WPCs) incorporated with different levels of boron compounds, borax/boric acid (BX/BA) (0.5:0.5 wt %) and zinc borate (ZB) (4, 8, or 12 wt %) were investigated. The effect of the coupling agent loading (2, 4, or 6 wt %), maleic anhydride-grafted PP (MAPP), on the...

  12. Injection molding of silicon carbide capable of being sintered without pressure

    NASA Technical Reports Server (NTRS)

    Muller-Zell, A.; Schwarzmeier, R.

    1984-01-01

    The most suitable SiC mass for injection molding of SiC articles (for subsequent pressureless sintering) consisted of beta SiC 84, a wax mixture 8, and polyethylene or polystyrene 8 parts. The most effective method for adding the binders was by dissolving them in a solvent and subsequent evaporation. The sequence of component addition was significant, and all parameters were optimized together rather than individually.

  13. Characterization of a polyvinyl alcohol-hydrogel artificial articular cartilage prepared by injection molding.

    PubMed

    Kobayashi, Masanori; Oka, Masanori

    2004-01-01

    We have developed a hip hemi-arthroplasty using polyvinyl alcohol-hydrogel (PVA-H) as the treatment for hip joint disorders in which the lesion is limited to the joint surface. In previous studies, we characterized the biocompatibility and the mechanical properties of PVA-H as an arthroplasty material. To fix PVA-H firmly to the bone, we have devised an implant composed of PVA-H and porous titanium fiber mesh (TFM). However, because of poor infiltration of the PVA solution into the pores of the TFM when using the low temperature crystallization method, the strength of the PVA-H-TFM interface was insufficient. Consequently, the infiltration method was improved by adopting high-pressure injection molding. With this improved method, the bonding strength of the interface increased remarkably. However, as this injection molding requires high temperature, various mechanical properties of the PVA-H might change with this treatment in comparison with the previous method. The purpose of this study was to investigate the effect of high temperature treatment on the mechanical properties of PVA-H as artificial articular cartilage, the tensile test and friction test were performed about new PVA-H. The results showed no significant mechanical deterioration of the PVA-H. This certified that the injection-molding method did not induce the change of the mechanical properties of PVA-H and indicated the potential of hemi-arthroplasty using PVA-H by this method in the future.

  14. An Elastic-Plastic and Strength Prediction Model for Injection-Molded Long-Fiber Thermoplastics

    SciTech Connect

    Nguyen, Ba Nghiep; Kunc, Vlastimil; Phelps, Jay; Tucker III, Charles L.; Bapanapalli, Satish K.

    2008-09-01

    This paper applies a recently developed model to predict the elastic-plastic stress/strain response and strength of injection-molded long-fiber thermoplastics (LFTs). The model combines a micro-macro constitutive modeling approach with experimental characterization and modeling of the composite microstructure to determine the composite stress/strain response and strength. Specifically, it accounts for elastic fibers embedded in a thermoplastic resin that exhibits the elastic-plastic behavior obeying the Ramberg-Osgood relation and J-2 deformation theory of plasticity. It also accounts for fiber length, orientation and volume fraction distributions in the composite formed by the injection-molding process. Injection-molded-long-glass-fiber/polypropylene (PP) specimens were prepared for mechanical characterization and testing. Fiber length, orientation, and volume fraction distributions were then measured at some selected locations for use in the computation. Fiber orientations in these specimens were also predicted using an anisotropic rotary diffusion model developed for LFTs. The stress-strain response of the as-formed composite was computed by an incremental procedure that uses the Eshelby’s equivalent inclusion method, the Mori-Tanaka assumption and a fiber orientation averaging technique. The model has been validated against the experimental stress-strain results obtained for these long-glass-fiber/PP specimens.

  15. Color measurement of plastics - From compounding via pelletizing, up to injection molding and extrusion

    NASA Astrophysics Data System (ADS)

    Botos, J.; Murail, N.; Heidemeyer, P.; Kretschmer, K.; Ulmer, B.; Zentgraf, T.; Bastian, M.; Hochrein, T.

    2014-05-01

    The typical offline color measurement on injection molded or pressed specimens is a very expensive and time-consuming process. In order to optimize the productivity and quality, it is desirable to measure the color already during the production. Therefore several systems have been developed to monitor the color e.g. on melts, strands, pellets, the extrudate or injection molded part already during the process. Different kinds of inline, online and atline methods with their respective advantages and disadvantages will be compared. The criteria are e.g. the testing time, which ranges from real-time to some minutes, the required calibration procedure, the spectral resolution and the final measuring precision. The latter ranges between 0.05 to 0.5 in the CIE L*a*b* system depending on the particular measurement system. Due to the high temperatures in typical plastics processes thermochromism of polymers and dyes has to be taken into account. This effect can influence the color value in the magnitude of some 10% and is barely understood so far. Different suitable methods to compensate thermochromic effects during compounding or injection molding by using calibration curves or artificial neural networks are presented. Furthermore it is even possible to control the color during extrusion and compounding almost in real-time. The goal is a specific developed software for adjusting the color recipe automatically with the final objective of a closed-loop control.

  16. Quality Control of Injection Molded Eyewear by Non-Contact Deflectometry

    NASA Astrophysics Data System (ADS)

    Speck, A.; Zelzer, B.; Langenbucher, A.; Eppig, T.

    2014-07-01

    Occupational eye wear such as safety spectacles are manufactured by injection molding techniques. Testing of the assembled safety spectacle lenses in transmission is state of the art, but there is a lack of surface measurement systems for occupational safety lenses. The purpose of this work was to validate a deflectometric setup for topography measurement, detection of defects and visualization of the polishing quality, e.g. casting indentations or impressions, for the production process of safety spectacles. The setup is based on a customized stereo phase measuring deflectometer (PMD), equipped with 3 cameras with f'1,2 = 16 mm and f'3 = 8.5 mm and a specified measurement uncertainty of ± 3 μm. Sixteen plastic lenses and 8 corresponding injection molds from 4 parallel cavities were used for validation of the deflectometer. For comparison an interferometric method and a reference standard (< λ/10 super polished) was used. The accuracy and bias with a spherical safety spectacle sample was below 1 μm, according to DIN ISO 5725-2.2002-12. The repeatability was 2.1 μm and 35.7 μm for a blind radius fit. In conclusion, the PMD technique is an appropriate tool for characterizing occupational safety spectacle and injections mold surfaces. With the presented setup we were able to quantify the surface quality. This can be useful and may optimize the quality of the end product, in addition to standardized measuring systems in transmission.

  17. Prediction of fiber orientation in injection-molded parts using three-dimensional simulations

    NASA Astrophysics Data System (ADS)

    Wang, Jin; Cook, Peter; Bakharev, Alex; Costa, Franco; Astbury, David

    2016-03-01

    The Folgar-Tucker (F-T) model is widely used in most commercial software packages and research programs to predict the fiber orientation distribution in injection-molded fiber-reinforced composites. However, experimental measurements reveal that the F-T model normally results in much higher fiber alignment than observed because it tends to over-predict the orientation kinetics. The Reduced Strain Closure (RSC) model was developed, based on the F-T model, to capture the slow orientation kinetics in an objective fashion. Previous studies demonstrate that t he RSC model yields good agreement of fiber orientation with experimental measurements in shell element simulations using the Hele-Shaw flow approximation. This paper focuses on the RSC model in three-dimensional finite element simulations. The fiber orientation predictions were compared to the orientation measurements in a number of injection-molded parts of various shapes and dimensions and molded with various injection speeds. The RSC model is able to capture the orientation distribution through the part thickness and the average orientation trends along the flow length without the need to tailor the inlet orientation condition to pre-existing data.

  18. Process development of injection molded parts with wound fiber structures for local reinforcement

    NASA Astrophysics Data System (ADS)

    Heinzle, V.; Huber, T.; Henning, F.; Elsner, P.

    2014-05-01

    Glass and carbon fiber reinforcements in injection molded parts have been used for many decades in combination with thermoplastics. Where short- or long-fiber pellets are used, all areas of the part are nearly equally reinforced by fibers. With local continuous-fiber reinforcements it is possible to reduce fiber usage to the most highly loaded areas of the components along the lines of flux. This method, which draws on principles applied in nature, strengthens the parts with only a slight weight increase compared to non-reinforced parts. The combination of injection molding as a process for large-scale production with the high mechanical properties of continuous-fiber-reinforcements enables the production of high-strength components at reasonable costs. The paper presents the investigation of a process development with injection molded components in combination with wound fiber structures. Fundamental experiments with tensile loaded wound fiber structures regarding to their design influences are presented. On this basis a reinforcement structure for a demonstrator was developed and examined.

  19. Recycling plastic scrap: Injection molding. (Latest citations from the Rubber and Plastics Research Association database). Published Search

    SciTech Connect

    1997-02-01

    The bibliography contains citations concerning the recycling of scrap plastic produced in the injection molding process. Plastic pellets made from scrap, that are used in the injection molding process, are also discussed. Recycling equipment and automated recycling systems are described. The reuse of plastic scrap culled from junk automobiles and packaging materials is discussed, and waste byproducts from polyurethane production are described. (Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

  20. Recycling plastic scrap: Injection molding. (Latest citations from the Rubber and Plastics Research Association database). Published Search

    SciTech Connect

    1995-01-01

    The bibliography contains citations concerning the recycling of scrap plastic produced in the injection molding process. Plastic pellets made from scrap, that are used in the injection molding process, are also discussed. Recycling equipment and automated recycling systems are described. The reuse of plastic scrap culled from junk automobiles and packaging materials is discussed, and waste byproducts from polyurethane production are described. (Contains a minimum of 88 citations and includes a subject term index and title list.)

  1. Recycling plastic scrap: Injection molding. (Latest citations from the Rubber and Plastics Research Association database). Published Search

    SciTech Connect

    1996-04-01

    The bibliography contains citations concerning the recycling of scrap plastic produced in the injection molding process. Plastic pellets made from scrap, that are used in the injection molding process, are also discussed. Recycling equipment and automated recycling systems are described. The reuse of plastic scrap culled from junk automobiles and packaging materials is discussed, and waste byproducts from polyurethane production are described. (Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

  2. Recycling plastic scrap: Injection molding. (Latest citations from the Rubber and Plastics Research Association database). Published Search

    SciTech Connect

    Not Available

    1994-05-01

    The bibliography contains citations concerning the recycling of scrap plastic produced in the injection molding process. Plastic pellets made from scrap, that are used in the injection molding process, are also discussed. Recycling equipment and automated recycling systems are described. The reuse of plastic scrap culled from junk automobiles and packaging materials is discussed, and waste byproducts from polyurethane production are described. (Contains a minimum of 80 citations and includes a subject term index and title list.)

  3. Wall-slip of highly filled powder injection molding compounds: Effect of flow channel geometry and roughness

    SciTech Connect

    Hausnerova, Berenika; Sanetrnik, Daniel; Paravanova, Gordana

    2014-05-15

    The paper deals with the rheological behavior of highly filled compounds proceeded via powder injection molding (PIM) and applied in many sectors of industry (automotive, medicine, electronic or military). Online rheometer equipped with slit dies varying in surface roughness and dimensions was applied to investigate the wall-slip as a rheological phenomenon, which can be considered as a parameter indicating the separation of compound components (polymer binder and metallic powder) during high shear rates when injection molded.

  4. 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.

  5. 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.

  6. Numerical approach of the injection molding process of fiber-reinforced composite with considering fiber orientation

    SciTech Connect

    Nguyen Thi, T. B. E-mail: yokoyama@kit.ac.jp; Yokoyama, A. E-mail: yokoyama@kit.ac.jp; Ota, K. E-mail: katsuhiro-kodama@toyobo.jp E-mail: yumiko-isogai@toyobo.jp E-mail: chisato-nonomura@toyobo.jp; Kodama, K. E-mail: katsuhiro-kodama@toyobo.jp E-mail: yumiko-isogai@toyobo.jp E-mail: chisato-nonomura@toyobo.jp; Yamashita, K. E-mail: katsuhiro-kodama@toyobo.jp E-mail: yumiko-isogai@toyobo.jp E-mail: chisato-nonomura@toyobo.jp; Isogai, Y. E-mail: katsuhiro-kodama@toyobo.jp E-mail: yumiko-isogai@toyobo.jp E-mail: chisato-nonomura@toyobo.jp; Furuichi, K. E-mail: katsuhiro-kodama@toyobo.jp E-mail: yumiko-isogai@toyobo.jp E-mail: chisato-nonomura@toyobo.jp; Nonomura, C. E-mail: katsuhiro-kodama@toyobo.jp E-mail: yumiko-isogai@toyobo.jp E-mail: chisato-nonomura@toyobo.jp

    2014-05-15

    One of the most important challenges in the injection molding process of the short-glass fiber/thermoplastic composite parts is being able to predict the fiber orientation, since it controls the mechanical and the physical properties of the final parts. Folgar and Tucker included into the Jeffery equation a diffusive type of term, which introduces a phenomenological coefficient for modeling the randomizing effect of the mechanical interactions between the fibers, to predict the fiber orientation in concentrated suspensions. Their experiments indicated that this coefficient depends on the fiber volume fraction and aspect ratio. However, a definition of the fiber interaction coefficient, which is very necessary in the fiber orientation simulations, hasn't still been proven yet. Consequently, this study proposed a developed fiber interaction model that has been introduced a fiber dynamics simulation in order to obtain a global fiber interaction coefficient. This supposed that the coefficient is a sum function of the fiber concentration, aspect ratio, and angular velocity. The proposed model was incorporated into a computer aided engineering simulation package C-Mold. Short-glass fiber/polyamide-6 composites were produced in the injection molding with the fiber weight concentration of 30 wt.%, 50 wt.%, and 70 wt.%. The physical properties of these composites were examined, and their fiber orientation distributions were measured by micro-computed-tomography equipment μ-CT. The simulation results showed a good agreement with experiment results.

  7. Numerical approach of the injection molding process of fiber-reinforced composite with considering fiber orientation

    NASA Astrophysics Data System (ADS)

    Nguyen Thi, T. B.; Yokoyama, A.; Ota, K.; Kodama, K.; Yamashita, K.; Isogai, Y.; Furuichi, K.; Nonomura, C.

    2014-05-01

    One of the most important challenges in the injection molding process of the short-glass fiber/thermoplastic composite parts is being able to predict the fiber orientation, since it controls the mechanical and the physical properties of the final parts. Folgar and Tucker included into the Jeffery equation a diffusive type of term, which introduces a phenomenological coefficient for modeling the randomizing effect of the mechanical interactions between the fibers, to predict the fiber orientation in concentrated suspensions. Their experiments indicated that this coefficient depends on the fiber volume fraction and aspect ratio. However, a definition of the fiber interaction coefficient, which is very necessary in the fiber orientation simulations, hasn't still been proven yet. Consequently, this study proposed a developed fiber interaction model that has been introduced a fiber dynamics simulation in order to obtain a global fiber interaction coefficient. This supposed that the coefficient is a sum function of the fiber concentration, aspect ratio, and angular velocity. The proposed model was incorporated into a computer aided engineering simulation package C-Mold. Short-glass fiber/polyamide-6 composites were produced in the injection molding with the fiber weight concentration of 30 wt.%, 50 wt.%, and 70 wt.%. The physical properties of these composites were examined, and their fiber orientation distributions were measured by micro-computed-tomography equipment μ-CT. The simulation results showed a good agreement with experiment results.

  8. Study of Warpage in Injection MoldingUsing Rubber and Talc-filled Polypropylene— Influence of Molding Conditions on Corner Deformation —

    NASA Astrophysics Data System (ADS)

    Takahara, Tadayoshi; Furuhashi, Hiroshi; Maeda, Hidenori; Inoyama, Tatsuya; Koyama, Kiyohito

    The most popular resin material for automotive plastic parts is polypropylene, which includes talc for stiffness and heat-resistance. The anisotropic thermal expansion coefficient is well documented for talc reinforced polypropylene, but there are almost no technical papers for warpage. Therefore, using this kind of material and molding with an "L" shaped cross section, the influence of molding conditions on corner deformation is discussed in this study. The results of this study are as follows 1) Shrinkage rate in the thickness direction is a few times larger than that in the planar direction (flow direction and transverse direction). By SEM observation, talc orientation for planar direction was confirmed. This talc orientation can hinder shrinkage in the planar direction, so the shrinkage rate in the thickness direction is relatively larger. 2) Three relationships were confirmed; negative correlation between injected weight (i.e. specimen weight) and shrinkage rate in the thickness direction, positive correlation between shrinkage rate in the thickness direction and corner deformation, and injected weight was varied by molding condition. From the results above, corner deformation is examined when; molding condition changes the injected weight, injected weight varies the shrinkage rate in the thickness direction, and when the shrinkage rate in the thickness direction induces corner deformation.

  9. Optimization of Micro Metal Injection Molding By Using Grey Relational Grade

    NASA Astrophysics Data System (ADS)

    Ibrahim, M. H. I.; Muhamad, N.; Sulong, A. B.; Nor, N. H. M.; Jamaludin, K. R.; Harun, M. R.; Murtadhahadi

    2011-01-01

    Micro metal injection molding (μMIM) which is a variant of MIM process is a promising method towards near net-shape of metallic micro components of complex geometry. In this paper, μMIM is applied to produce 316L stainless steel micro components. Due to highly stringent characteristic of μMIM properties, the study has been emphasized on optimization of process parameter where Taguchi method associated with Grey Relational Analysis (GRA) will be implemented as it represents novel approach towards investigation of multiple performance characteristics. Basic idea of GRA is to find a grey relational grade (GRG) which can be used for the optimization conversion from multi objectives case which are density and strength to a single objective case. After considering the form `the larger the better', results show that the injection time(D) is the most significant followed by injection pressure(A), holding time(E), mold temperature(C) and injection temperature(B). Analysis of variance (ANOVA) is also employed to strengthen the significant of each parameter involved in this study.

  10. Optimization of Micro Metal Injection Molding By Using Grey Relational Grade

    SciTech Connect

    Ibrahim, M. H. I.; Muhamad, N.; Sulong, A. B.; Nor, N. H. M.; Harun, M. R.; Murtadhahadi; Jamaludin, K. R.

    2011-01-17

    Micro metal injection molding ({mu}MIM) which is a variant of MIM process is a promising method towards near net-shape of metallic micro components of complex geometry. In this paper, {mu}MIM is applied to produce 316L stainless steel micro components. Due to highly stringent characteristic of {mu}MIM properties, the study has been emphasized on optimization of process parameter where Taguchi method associated with Grey Relational Analysis (GRA) will be implemented as it represents novel approach towards investigation of multiple performance characteristics. Basic idea of GRA is to find a grey relational grade (GRG) which can be used for the optimization conversion from multi objectives case which are density and strength to a single objective case. After considering the form 'the larger the better', results show that the injection time(D) is the most significant followed by injection pressure(A), holding time(E), mold temperature(C) and injection temperature(B). Analysis of variance (ANOVA) is also employed to strengthen the significant of each parameter involved in this study.

  11. Determination of physical properties in injection molded composites using the design of experiments method

    SciTech Connect

    Hawks, V.; Saunders, D.; Strong, A.B.; Cole, D. )

    1992-07-01

    The benefits of using Design of Experiments (DOE) for determining effects of critical factors are significantly greater than using one-at-a-time experimental techniques. The volume and validity of the information gained from DOE, especially for manufacturing processes, is very high due to the strong statistical basis of the method and highly organized nature of the results. The use of DOE is described in the case of injection molding of composites to improve and better understand the effects of critical factors on the physical properties of the finished parts. The factors, fiber length, fiber concentration, part temperature, and mold thickness, were tested using a full factorial experiment. The results demonstrated the significance of the factors and their interactions on tensile strength, modulus of elasticity, and elongation.

  12. Investigation of sample preparation on the moldability of ceramic injection molding feedstocks

    NASA Astrophysics Data System (ADS)

    Ide, Jared

    Ceramic injection molding is a desirable option for those who are looking to make ceramic parts with complex geometries. Formulating the feedstock needed to produce ideal parts is a difficult process. In this research a series of feedstock blends will be evaluated for moldability. This was done by investigating their viscosity, and how certain components affect the overall ability to flow. These feedstocks varied waxes, surfactants, and solids loading. A capillary rheometer was used to characterize some of the materials, which led to one batch being selected for molding trials. The parts were sintered and further refinements were made to the feedstock. Solids loading was increased from 77.5% to 82%, which required different ratios of organics to flow. Finally, the ceramic powders were treated to lower their specific surface area before being compounded, which resulted in materials that would process easily through an extruder and exhibit properties suitable for CIM.

  13. Injection-Molded Long-Fiber Thermoplastic Composites: From Process Modeling to Prediction of Mechanical Properties

    SciTech Connect

    Nguyen, Ba Nghiep; Kunc, Vlastimil; Jin, Xiaoshi; Tucker III, Charles L.; Costa, Franco

    2013-12-18

    This article illustrates the predictive capabilities for long-fiber thermoplastic (LFT) composites that first simulate the injection molding of LFT structures by Autodesk® Simulation Moldflow® Insight (ASMI) to accurately predict fiber orientation and length distributions in these structures. After validating fiber orientation and length predictions against the experimental data, the predicted results are used by ASMI to compute distributions of elastic properties in the molded structures. In addition, local stress-strain responses and damage accumulation under tensile loading are predicted by an elastic-plastic damage model of EMTA-NLA, a nonlinear analysis tool implemented in ABAQUS® via user-subroutines using an incremental Eshelby-Mori-Tanaka approach. Predicted stress-strain responses up to failure and damage accumulations are compared to the experimental results to validate the model.

  14. Comparison of Candida Albicans Adherence to Conventional Acrylic Denture Base Materials and Injection Molding Acrylic Materials

    PubMed Central

    Aslanimehr, Masoomeh; Rezvani, Shirin; Mahmoudi, Ali; Moosavi, Najmeh

    2017-01-01

    Statement of the Problem: Candida species are believed to play an important role in initiation and progression of denture stomatitis. The type of the denture material also influences the adhesion of candida and development of stomatitis. Purpose: The aim of this study was comparing the adherence of candida albicans to the conventional and injection molding acrylic denture base materials. Materials and Method: Twenty injection molding and 20 conventional pressure pack acrylic discs (10×10×2 mm) were prepared according to their manufacturer’s instructions. Immediately before the study, samples were placed in sterile water for 3 days to remove residual monomers. The samples were then sterilized using an ultraviolet light unit for 10 minutes. 1×108 Cfu/ml suspension of candida albicans ATCC-10231 was prepared from 48 h cultured organism on sabouraud dextrose agar plates incubated at 37oC. 100 μL of this suspension was placed on the surface of each disk. After being incubated at 37oC for 1 hour, the samples were washed with normal saline to remove non-adherent cells. Attached cells were counted using the colony count method after shaking at 3000 rmp for 20 seconds. Finally, each group was tested for 108 times and the data were statistically analyzed by t-test. Results: Quantitative analysis revealed that differences in colony count average of candida albicans adherence to conventional acrylic materials (8.3×103) comparing to injection molding acrylic resins (6×103) were statistically significant (p<0.001). Conclusion: Significant reduction of candida albicans adherence to the injection acrylic resin materials makes them valuable for patients with high risk of denture stomatitis. PMID:28280761

  15. Simulation and experiment research on the proportional pressure control of water-assisted injection molding

    NASA Astrophysics Data System (ADS)

    Zhou, Hua; Chen, Yinglong; Zhang, Zengmeng; Yang, Huayong

    2012-05-01

    Water-assisted injection molding (WAIM), a newly developed fluid-assisted injection molding technology has drawn more and more attentions for the energy saving, short cooling circle time and high quality of products. Existing research for the process of WAIM has shown that the pressure control of the injecting water is mostly important for the WAIM. However, the proportional pressure control for the WAIM system is quite complex due to the existence of nonlinearities in the water hydraulic system. In order to achieve better pressure control performance of the injecting water to meet the requirements of the WAIM, the proportional pressure control of the WAIM system is investigated both numerically and experimentally. A newly designed water hydraulic system for WAIM is first modeled in AMEsim environment, the load characteristics and the nonlinearities of water hydraulic system are both considered, then the main factors affecting the injecting pressure and load flow rate are extensively studied. Meanwhile, an open-loop model-based compensation control strategy is employed to regulate the water injection pressure and a feedback proportional integrator controller is further adopted to achieve better control performance. In order to verify the AMEsim simulation results WAIM experiment for particular Acrylonitrile Butadiene Styrene (ABS) parts is implemented and the measured experimental data including injecting pressure and flow rate results are compared with the simulation. The good coincidence between experiment and simulation shows that the AMEsim model is accurate, and the tracking performance of the load pressure indicates that the proposed control strategy is effective for the proportional pressure control of the nonlinear WAIM system. The proposed proportional pressure control strategy and the conclusions drawn from simulation and experiment contribute to the application of water hydraulic proportional control and WAIM technology.

  16. Optimal Design of Material and Process Parameters in Powder Injection Molding

    NASA Astrophysics Data System (ADS)

    Ayad, G.; Barriere, T.; Gelin, J. C.; Song, J.; Liu, B.

    2007-04-01

    The paper is concerned with optimization and parametric identification for the different stages in Powder Injection Molding process that consists first in injection of powder mixture with polymer binder and then to the sintering of the resulting powders part by solid state diffusion. In the first part, one describes an original methodology to optimize the process and geometry parameters in injection stage based on the combination of design of experiments and an adaptive Response Surface Modeling. Then the second part of the paper describes the identification strategy that one proposes for the sintering stage, using the identification of sintering parameters from dilatometeric curves followed by the optimization of the sintering process. The proposed approaches are applied to the optimization of material and process parameters for manufacturing a ceramic femoral implant. One demonstrates that the proposed approach give satisfactory results.

  17. Anisotropic mechanical behavior of an injection molded short fiber reinforced thermoplastic

    NASA Astrophysics Data System (ADS)

    Lopez, Delphine; Thuillier, Sandrine; Bessières, Nicolas; Grohens, Yves

    2016-10-01

    A short fiber reinforced thermoplastic was injected into a rectangular mold, in order to prepare samples to characterize the mechanical behavior of the material. The injection process was simulated with Moldflow and a cutting pattern was deduced from the predicted fiber orientation, leading to samples with several well-defined orientations with respect to the injection direction. Monotonic tensile tests up to rupture, as well as complex cycles made of loading steps followed by relaxation steps at different strain levels were performed, in order to check the reproducibility for a given orientation. Moreover, the fiber orientation in the central part of the tensile samples was also analyzed with X-ray tomography. The results show that the mechanical behavior for each orientation (among 6) was rather reproducible, thus validating the cutting pattern.

  18. Using Direct Metal Deposition to Fabricate Mold Plates for an Injection Mold Machine Allowing for the Evaluation of Cost Effective Near-Sourcing Opportunities in Larger, High Volume Consumer Products

    SciTech Connect

    Duty, Chad E; Groh, Bill

    2014-10-31

    ORNL collaborated with Radio Systems Corporation to investigate additive manufacturing (AM) of mold plates for plastic injection molding by direct metal deposition. The team s modelling effort identified a 100% improvement in heat transfer through use of conformal cooling lines that could be built into the mold using a revolutionary design enabled by additive manufacturing. Using the newly installed laser deposition system at the ORNL Manufacturing Demonstration Facility (MDF) a stainless steel mold core was printed.

  19. Interfacial crystalline structures in injection over-molded polypropylene and bond strength.

    PubMed

    Yan, Bowen; Wu, Hong; Jiang, Genjie; Guo, Shaoyun; Huang, Jian

    2010-11-01

    This paper describes interfacial crystalline structures found in injection overmolded polypropylene components and the relationship of these structures to bond strength between the components. The combined effects of the development of hierarchical gradient structures and the particular thermomechanical environment near the interface on the interfacial crystalline structures were investigated in detail by PLM, SEM, DSC, WAXD, and infrared dichroism spectroscopy. The experimental results showed that during molding there was competitive formation of interfacial crystalline structures consisted of "shish-kebab" layer (SKL) and a transcrystalline layers (TCL). Variation in shear stress (controlled by injection pressure and injection speed) plays an important role in the formation of the SKL. The formation of TCL is influenced by the thermal environment, namely melt temperature and mold temperature. Increasing within certain limits, interfacial temperature and the thermal gradient near the interface promotes β-iPP growth. The relationship between interfacial crystalline structures and interfacial bond strength was established by lap shear measurement. The interfacial bond strength is improved by enhancing the formation of TCL, but reduced if SKL predominates.

  20. Numerical Simulation of the Flow Behavior and Breakthrough Phenomenon in Co-Injection Molding

    NASA Astrophysics Data System (ADS)

    Ilinca, Florin; Hétu, Jean-François

    2007-05-01

    A study of the flow behavior during sequential co-injection molding is shown using a three-dimensional finite element flow analysis code. Solutions of the non-Newtonian, non-isothermal melt flow are obtained by solving the momentum, continuity and energy equations. Two additional transport equations are solved for tracking polymer/air and skin/core polymers interfaces. The co-injection model is integrated into the NRC's 3D injection molding software. Solutions are shown for the filling of a spiral-flow mould for which experimental measurements are available. The numerical approach predicts the core advance stage during which the core flow front catches up on the skin flow front and the core expansion phase when the flow fronts of core and skin materials advance together without breakthrough. The breakthrough phenomenon is also predicted. The predicted flow front behavior is compared to the experimental observations for various skin/core melt temperature and skin/core viscosity ratio. Simulation results are in good agreement with experimental data and indicate correctly the trends in solution change when processing parameters are changing.

  1. Effect of Reinforcement on the Flexural Properties of Injection-Molded Thermoplastic Denture Base Resins.

    PubMed

    Sasaki, Hirono; Hamanaka, Ippei; Takahashi, Yutaka; Kawaguchi, Tomohiro

    2017-06-01

    To evaluate the effect of reinforcement on the flexural properties of injection-molded thermoplastic denture base resins. Three injection-molded thermoplastic denture base resins (polyamide, polyester, polycarbonate) were selected for this study, and a conventional heat-polymerized denture base resin (PMMA) was used as a control. Continuous unidirectional glass fiber-reinforced composite (FRC) and metal wire were used for reinforcement. Reinforced bar-shaped specimens (65 mm long, 10 mm wide, 3.3 mm high) were fabricated (n = 10). The flexural strength at the proportional limit (FS-PL) and the elastic modulus were measured using a three-point bending test. All the denture base material specimens reinforced with FRC possessed a significantly higher FS-PL compared to those without reinforcement. The FS-PL of the polycarbonate specimens reinforced with metal wire was significantly higher than that without reinforcement, and there was no significant difference in the FS-PL between the polycarbonate specimens reinforced with FRC and those with metal wire. The order of the elastic modulus according to the denture base material, arranged in terms of statistical significance, was as follows: PMMA (3.46 ± 0.53 GPa) > polycarbonate (2.69 ± 0.48 GPa) > polyester (2.00 ± 0.39 GPa) > polyamide (1.14 ± 0.35 GPa). The order of the elastic modulus according to the reinforcement, arranged in terms of statistical significance, was as follows: metal wire (2.74 ± 0.96 GPa) > FRC (2.40 ± 0.89 GPa) > no reinforcement (1.82 ± 0.83 GPa). Continuous unidirectional glass fiber-reinforced composite (FRC) reinforcement had a satisfactory reinforcing effect for the injection-molded thermoplastic denture base resins. © 2015 by the American College of Prosthodontists.

  2. Mechanical Properties of Injection Molded B 4C-C Ceramics

    NASA Astrophysics Data System (ADS)

    Schwetz, Karl A.; Sigl, Lorenz S.; Pfau, Lothar

    1997-10-01

    Various mechanical properties of carbon-doped boron carbide ceramics, prepared by the fabrication route, injection molding/pressureless sintering/post-hot isostatic pressing (HIP) were investigated as a function of the sintering temperature and the carbon additive level used. An optimum combination of mechanical properties (flexural stregth, fracture toughness, Young's modulus, Knoop's hardness) is thus obtained with 100% dense and very fine grained materials (mean grain size 1-4 μm) which were sintered at temperatures from 2150 to 2175°C and post-HIPed at 2050°/200 MPa Ar, having an approximate final composition of 96 B4C-4C (wt%).

  3. Fabrication of Micro Gears by Micro-Powder Injection-Compression Molding

    NASA Astrophysics Data System (ADS)

    Jang, Jin Man; Lee, Wonsik; Son, Seong-Ho; Ko, Se-Hyun; Kim, Il-Ho

    Micro-spur gears were fabricated by powder injection-compression molding and micro-two-step gears were produced through stacking and sintering of the green parts. Shrinkage of micro-gears by sintering was larger in teeth and with increase of compression pressure, shrinkage was decreased due to increase of density in green parts. Surface roughness of sintered body was reduced to a few hundreds of nanometers by ultrasonic micro-polishing. The joining of green bodies by stacking and sintering was achieved using the pressurized sintering and insert of feedstock powders between both green bodies.

  4. Effect of rheological parameters on curing rate during NBR injection molding

    NASA Astrophysics Data System (ADS)

    Kyas, Kamil; Stanek, Michal; Manas, David; Skrobak, Adam

    2013-04-01

    In this work, non-isothermal injection molding process for NBR rubber mixture considering Isayev-Deng curing kinetic model, generalized Newtonian model with Carreau-WLF viscosity was modeled by using finite element method in order to understand the effect of volume flow rate, index of non-Newtonian behavior and relaxation time on the temperature profile and curing rate. It was found that for specific geometry and processing conditions, increase in relaxation time or in the index of non-Newtonian behavior increases the curing rate due to viscous dissipation taking place at the flow domain walls.

  5. Compact surface plasmon resonance biosensor utilizing an injection-molded prism

    NASA Astrophysics Data System (ADS)

    Chen, How-Foo; Chen, Chih-Han; Chang, Yun-Hsiang; Chuang, Hsin-Yuan

    2016-05-01

    Targeting at a low cost and accessible diagnostic device in clinical practice, a compact surface plasmon resonance (SPR) biosensor with a large dynamic range in high sensitivity is designed to satisfy commercial needs in food safety, environmental bio-pollution monitoring, and fast clinical diagnosis. The core component integrates an optical coupler, a sample-loading plate, and angle-tuning reflectors is injection-molded as a free-from prism made of plastic optics. This design makes a matching-oil-free operation during operation. The disposability of this low-cost component ensures testing or diagnosis without cross contamination in bio-samples.

  6. Occupational exposure to bisphenol A (BPA) in a plastic injection molding factory in Malaysia.

    PubMed

    Kouidhi, Wided; Thannimalay, Letchumi; Soon, Chen Sau; Ali Mohd, Mustafa

    2017-07-14

    The purpose of this study has been to assess ambient bisphenol A (BPA) levels in workplaces and urine levels of workers and to establish a BPA database for different populations in Malaysia. Urine samples were collected from plastic factory workers and from control subjects after their shift. Air samples were collected using gas analyzers from 5 sampling positions in the injection molding unit work area and from ambient air. The level of BPA in airborne and urine samples was quantified by the gas chromatography mass spectrometry - selected ion monitoring (GCMS-SIM) analysis. Bisphenol A was detected in the median range of 8-28.3 ng/m³ and 2.4-3.59 ng/m³ for the 5 sampling points in the plastic molding factory and in the ambient air respectively. The median urinary BPA concentration was significantly higher in the workers (3.81 ng/ml) than in control subjects (0.73 ng/ml). The urinary BPA concentration was significantly associated with airborne BPA levels (ρ = 0.55, p < 0.01). Our findings provide the first evidence that workers in a molding factory in Malaysia are occupationally exposed to BPA. Int J Occup Med Environ Health 2017;30(5):743-750.

  7. Application of knowledge-based vision to closed-loop control of the injection molding process

    NASA Astrophysics Data System (ADS)

    Marsh, Robert; Stamp, R. J.; Hill, T. M.

    1997-10-01

    An investigation is under way to develop a control system for an industrial process which uses a vision systems as a sensor. The research is aimed at the improvement of product quality in commercial injection molding system. A significant enhancement has been achieved in the level of application of visually based inspection techniques to component quality. The aim of the research has been the investigation, and employment, of inspection methods that use knowledge based machine vision. The application of such techniques in this context is comprehensive, extending from object oriented analysis, design and programming of the inspection program, to the application of rule based reasoning, to image interpretation, vision system diagnostics, component diagnostics and molding machine control. In this way, knowledge handling methods are exploited wherever they prove to be beneficial. The vision knowledge base contains information on the procedures required to achieve successful identification of component surface defects. A collection of image processing and pattern recognition algorithms are applied selectively. Once inspection of the component has been performed, defects are related to process variables which affect the quality of the component, and another knowledge base is used to effect a control action at the molding machine. Feedback from other machine sensor is also used to direct the control procedure. Results from the knowledge based vision inspection system are encouraging. They indicate that rapid and effective fault detection and analysis is feasible, as is the verification of system integrity.

  8. Enteric-coating of pulsatile-release HPC capsules prepared by injection molding.

    PubMed

    Macchi, E; Zema, L; Maroni, A; Gazzaniga, A; Felton, L A

    2015-04-05

    Capsular devices based on hydroxypropyl cellulose (Klucel® LF) intended for pulsatile release were prepared by injection molding (IM). In the present work, the possibility of exploiting such capsules for the development of colonic delivery systems based on a time-dependent approach was evaluated. For this purpose, it was necessary to demonstrate the ability of molded cores to undergo a coating process and that coated systems yield the desired performance (gastric resistance). Although no information was available on the coating of IM substrates, some issues relevant to that of commercially-available capsules are known. Thus, preliminary studies were conducted on molded disks for screening purposes prior to the spray-coating of HPC capsular cores with Eudragit® L 30 D 55. The ability of the polymeric suspension to wet the substrate, spread, start penetrating and initiate hydration/swelling, as well as to provide a gastroresistant barrier was demonstrated. The coating of prototype HPC capsules was carried out successfully, leading to coated systems with good technological properties and able to withstand the acidic medium with no need for sealing at the cap/body joint. Such systems maintained the original pulsatile release performance after dissolution of the enteric film in pH 6.8 fluid. Therefore, they appeared potentially suitable for the development of a colon delivery platform based on a time-dependent approach. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Rheological study of copper and copper grapheme feedstock for powder injection molding

    NASA Astrophysics Data System (ADS)

    Azaman, N. Emira Binti; Rafi Raza, M.; Muhamad, N.; Niaz Akhtar, M.; Bakar Sulong, A.

    2017-01-01

    Heatsink is one of the solution to optimize the performance of smart electronic devices. Copper and its composites are helping the electronic industry to solve the heating problem. Copper-graphene heat sink material with enhanced thermal conductivity is the ultimate goal.Powder injection molding (PIM) has advantages of high precision and production rate, complex shape, low cost and suitabality for metal and cremics.PIM consists of four sub sequential steps; feedstock preparation, molding, debinding and sintering. Feedstock preparation is a critical step in PIM process. Any deficiency at this stage cannot be recovered at latter stages. Therefore, this research was carried out to investigate the injectability of copper and copper graphene composite using PIM. PEG based multicomponent binder system was used and the powder loading was upto 7vol.% less than the critical powder loading was used to provide the wettability of the copper powder and graphene nanoplatelets (GNps). Corpper-graphene feedstock contained 0.5vol.% of GNps . To ensure the homogeneity of GNps within feedstock a unique technique was addopted. The microscopic results showed that the feedstock is homogeneous and ready for injection. The viscosity-shear rate relationship was determined and results showed that the addition of 0.5vol.% of GNps in copper has increased the viscosity upto 64.9% at 140˚C than that of pure copper feedstock. This attribute may be due to the large surface area of GNps. On the other hand, by increasing the temperature, viscosity of the feedstock was decreased, which was recommended for PIM. The overall viscosity and share rate lies within the range recommended for PIM process. It is clear that both feedstocks showed pseudo plastic behaviour which is suitable for PIM process. In the pseudo plastic behaviour, the viscosity decreases with the shear rate. It may be due to change in the structure of the solid particles or the binder. The molding results showed that both copper

  10. Exposures to nanoparticles and fibers during injection molding and recycling of carbon nanotube reinforced polycarbonate composites.

    PubMed

    Boonruksa, Pongsit; Bello, Dhimiter; Zhang, Jinde; Isaacs, Jacqueline A; Mead, Joey L; Woskie, Susan R

    2016-05-18

    In this study, the characteristics of airborne particles generated during injection molding and grinding processes of carbon nanotube reinforced polycarbonate composites (CNT-PC) were investigated. Particle number concentration, size distribution, and morphology of particles emitted from the processes were determined using real-time particle sizers and transmission electron microscopy. The air samples near the operator's breathing zone were collected on filters and analyzed using scanning electron microscope for particle morphology and respirable fiber count. Processing and grinding during recycling of CNT-PC released airborne nanoparticles (NPs) with a geometric mean (GM) particle concentration from 4.7 × 10(3) to 1.7 × 10(6) particles/cm(3). The ratios of the GM particle concentration measured during the injection molding process with exhaust ventilation relative to background were up to 1.3 (loading), 1.9 (melting), and 1.4 (molding), and 101.4 for grinding process without exhaust ventilation, suggesting substantial NP exposures during these processes. The estimated mass concentration was in the range of 1.6-95.2 μg/m(3). Diverse particle morphologies, including NPs, NP agglomerates, particles with embedded or protruding CNTs and fibers, were observed. No free CNTs were found during any of the investigated processes. The breathing zone respirable fiber concentration during the grinding process ranged from non-detectable to 0.13 fiber/cm(3). No evidence was found that the emissions were affected by the number of recycling cycles. Institution of exposure controls is recommended during these processes to limit exposures to airborne NPs and CNT-containing fibers.Journal of Exposure Science and Environmental Epidemiology advance online publication, 18 May 2016; doi:10.1038/jes.2016.26.

  11. [The control of microstructures during consolidation and injection molding of colloidal dispersions]. Progress report

    SciTech Connect

    Not Available

    1991-12-31

    The existing three-year grant pertaining to ``The control of micro-structures during consolidation and injection molding of colloidal dispersions`` began July 1, 1988 as a continuation of a previous grant. The overall effort seeks to answer fundamental questions relevant to the colloidal processing of submicron particles leading to ceramic materials for strutural, electronic, or optical applications. At the outset two distinct projects were envisioned, an exploration of the ultrasonic enhancement of disorder-order transitions and a detailed study of injection molding of very dense dispersion, with each weighted toward experiments but with theoretical components. As the effort evolved the focus shifted in response to the interests of the students attracted to the project, the identification of interesting related problems through technical meetings, and different insights gained during participation in a DOE sponsored workshop. The scope that has emerged encompasses: completion of research begun during the first grant period on disorder-order transitions occurring during sedimentation, the consolidation of flocculated dispersions via filtration and the assembly of nanometer-sized particle into dense packings.

  12. (The control of microstructures during consolidation and injection molding of colloidal dispersions)

    SciTech Connect

    Not Available

    1991-01-01

    The existing three-year grant pertaining to The control of micro-structures during consolidation and injection molding of colloidal dispersions'' began July 1, 1988 as a continuation of a previous grant. The overall effort seeks to answer fundamental questions relevant to the colloidal processing of submicron particles leading to ceramic materials for strutural, electronic, or optical applications. At the outset two distinct projects were envisioned, an exploration of the ultrasonic enhancement of disorder-order transitions and a detailed study of injection molding of very dense dispersion, with each weighted toward experiments but with theoretical components. As the effort evolved the focus shifted in response to the interests of the students attracted to the project, the identification of interesting related problems through technical meetings, and different insights gained during participation in a DOE sponsored workshop. The scope that has emerged encompasses: completion of research begun during the first grant period on disorder-order transitions occurring during sedimentation, the consolidation of flocculated dispersions via filtration and the assembly of nanometer-sized particle into dense packings.

  13. Bulk and Surface Molecular Orientation Distribution in Injection-molded Liquid Crystalline Polymers: Experiment and Simulation

    SciTech Connect

    Fang, J.; Burghardt, W; Bubeck, R; Burgard, S; Fischer, D

    2010-01-01

    Bulk and surface distributions of molecular orientation in injection-molded plaques of thermotropic liquid crystalline polymers (TLCPs) have been studied using a combination of techniques, coordinated with process simulations using the Larson-Doi 'polydomain' model. Wide-angle X-ray scattering was used to map out the bulk orientation distribution. Fourier Transform Infrared Attenuated Total Reflectance (FTIR-ATR) and Near-Edge X-ray Absorption Fine Structure (NEXAFS) were utilized to probe the molecular orientation states to within about {approx}5 {micro}m and {approx}2 nm, respectively, of the sample surface. These noninvasive, surface-sensitive techniques yield reasonable self-consistency, providing complementary validation of the robustness of these methods. An analogy between Larson-Doi and fiber orientation models has allowed the first simulations of TLCP injection molding. The simulations capture many fine details in the bulk orientation distribution across the sample plaque. Direct simulation of surface orientation at the level probed by FTIR-ATR and NEXAFS was not possible due to the limited spatial resolution of the simulations. However, simulation results extracted from the shear-dominant skin region are found to provide a qualitatively accurate indicator of surface orientation. Finally, simulations capture the relation between bulk and surface orientation states across the different regions of the sample plaque.

  14. The effects of process parameters on injection-molded PZT ceramics part fabrication- compounding process rheology.

    SciTech Connect

    Halbleib, Laura L.; Yang, Pin; Mondy, Lisa Ann; Burns, George Robert

    2005-05-01

    Solid solutions of lead-based perovskites are the backbone materials of the piezoelectric components for transducer, actuator, and resonator applications. These components, typically small in size, are fabricated from large sintered ceramic slugs using grinding and lapping processes. These operations increase manufacturing costs and produce a large hazardous waste stream, especially when component size decreases. To reduce costs and hazardous wastes associated with the production of these components, an injection molding technique is being investigated to replace the machining processes. The first step in the new technique is to compound an organic carrier with a ceramic powder. The organic carrier is a thermoplastic based system composed of a main carrier, a binder, and a surfactant. Understanding the rheology of the compounded material is necessary to minimize the creation of defects such as voids or cavities during the injection-molding process. An experiment was performed to model the effects of changes in the composition and processing of the material on the rheological behavior. Factors studied included: the surfactant of the organic carrier system, the solid loading of the compounded material, and compounding time. The effects of these factors on the viscosity of the material were investigated.

  15. Time-Dependent Properties of Multimodal Polyoxymethylene Based Binder for Powder Injection Molding

    NASA Astrophysics Data System (ADS)

    Gonzalez-Gutierrez, Joamin; Stringari, Gustavo Beulke; Zupancic, Barbara; Kubyshkina, Galina; Bernstorff, Bernd Von; Emri, Igor

    Powder injection molding (PIM) is one of the most versatile methods for the manufacturing of small complex shaped components from metal, ceramic or cemented carbide powders for the use in many applications. PIM consists of mixing the powder and a polymeric binder, injecting this mixture in a mold, debinding and then sintering. Catalytic debinding of polyoxymethylene (POM) is attractive since it shows high debinding rates and low risk of cracking. This work examines the possibility of using POM with bimodal molecular mass distribution as the main component of the binding agent by studying its time-dependent properties and comparing them to monomodal POM. Furthermore, possible optimization of the binder formulation was investigated by the addition of shorter polymeric chains (wax) to bimodal POM, as to create a multimodal material. It was observed that the magnitude of the complex viscosity for the commercial bimodal material was more than 2 times lower than for the chemically identical monomodal POM within the investigated frequency range and temperature. Viscosity values were observed to drop as the content of wax was increased, without compromising the binders mechanical properties in solid state. A new formulation of bimodal POM plus 8 wt.% of added wax provided the most appropriate results from investigated combinations. This work has shown how the addition of short polymeric chains in POM influences its time-dependent properties in solid and molten state, which can be an important tool for the optimization of binders designed to be used in PIM technology.

  16. Magnesium Powder Injection Molding (MIM) of Orthopedic Implants for Biomedical Applications

    NASA Astrophysics Data System (ADS)

    Wolff, M.; Schaper, J. G.; Suckert, M. R.; Dahms, M.; Ebel, T.; Willumeit-Römer, R.; Klassen, T.

    2016-04-01

    Metal injection molding (MIM) has a high potential for the economic near-net-shape mass production of small-sized and complex-shaped parts. The motivation for launching Mg into the MIM processing chain for manufacturing biodegradable medical implants is related to its compatibility with human bone and its degradation in a non-toxic matter. It has been recognized that the load-bearing capacity of MIM Mg parts is superior to that of biodegradable polymeric components. However, the choice of appropriate polymeric binder components and alloying elements enabling defect-free injection molding and sintering is a major challenge for the use of MIM Mg parts. This study considered the full processing chain for MIM of Mg-Ca alloys to achieve ultimate tensile strength of up to 141 MPa with tensile yield strength of 73 MPa, elongation at fracture Af of 7% and a Young's modulus of 38 GPa. To achieve these mechanical properties, a thermal debinding study was performed to determine optimal furnace and atmosphere conditions, sintering temperature, heating rates, sintering time and pressure.

  17. Rheological and thermal performance of newly developed binder systems for ceramic injection molding

    NASA Astrophysics Data System (ADS)

    Hausnerova, Berenika; Kasparkova, Vera; Hnatkova, Eva

    2016-05-01

    In a novel binder system, carnauba wax was considered to replace the synthetic backbone polymers (polyolefins) enhancing the environmental sustainability of Ceramic Injection Molding (CIM) technology. The paper presents comparison of the rheological performance and thermal behavior of the aluminum oxide CIM feedstocks based on a binder containing carnauba wax with those consisting of a commercial binder. Further, acrawax (N, N'-Ethylene Bis-stearamide) has been considered as another possible substitute of polyolefins. For both proposed substitutes there is a significant reduction in viscosity, and in case of carnauba wax based feedstock also in processing temperature, which is essential for injection molding of reactive powders. Thermal characterization comprised analyses of single neat binders, their mixtures and mixtures with aluminum oxide. The presence of powder lowered melting temperatures of all tested binders except of polyolefin. Further depression in melting point of poly(ethylene glycol) is observed in combination with polyolefin in the presence of powder, and it is related to changes in size of the crystalline domains.

  18. The effect of cycling deflection on the injection-molded thermoplastic denture base resins.

    PubMed

    Hamanaka, Ippei; Iwamoto, Misa; Lassila, Lippo Vj; Vallittu, Pekka K; Shimizu, Hiroshi; Takahashi, Yutaka

    2016-01-01

    The aim of this study was to evaluate the effect of cycling deflection on the flexural behavior of injection-molded thermoplastic resins. Six injection-molded thermoplastic resins (two polyamides, two polyesters, one polycarbonate, one polymethyl methacrylate) and, as a control, a conventional heat-polymerized denture based polymer of polymethyl methacrylate (PMMA) were used in this study. The cyclic constant magnitude (1.0 mm) of 5000 cycles was applied using a universal testing machine to demonstrate plasticization of the polymer. Loading was carried out in water at 23ºC with eight specimens per group (n = 8). Cycling load (N) and deformation (mm) were measured. Force required to deflect the specimens during the first loading cycle and final loading cycle was statistically significantly different (p < 0.05) with one polyamide based polymer (Valplast) and PMMA based polymers (Acrytone and Acron). The other polyamide based polymer (LucitoneFRS), polyester based polymers (EstheShot and EstheShotBright) and polycarbonate based polymer (ReigningN) did not show significant differences (p > 0.05). None of the materials fractured during the loading test. One polyamide based polymer (Valplast) displayed the highest deformation and PMMA based polymers (Acrytone and Acron) exhibited the second highest deformation among the denture base materials. It can be concluded that there were considerable differences in the flexural behavior of denture base polymers. This may contribute to the fatigue resistance of the materials.

  19. Shear controlled alignment of short carbon fibers in copper matrix composite green samples produced by powder injection molding

    NASA Astrophysics Data System (ADS)

    Shirazi, Irfan; Ahmad, Faiz; Raza, M. Rafi; Muhsan, Ali. S.; Aslam, M.

    2015-07-01

    The tensile properties of short fiber reinforced composites are enhanced if fiber alignment in the load direction is achieved. Powder injection molding provides partial alignment of fibers in molded parts and shows a skin-core effect. The objective of this study was to align fibers completely in flow direction and reducing skin-core effect in green samples. This objective was achieved by changing the type of flow during molding by changing sprue geometry in a way that diverging flow is developed in it. This diverging flow was converted to converging flow when feedstock entered mold cavity and generated shear to align fibers. This sprue modification was helpful in aligning short fibers in flow direction and eliminating skin-core effect.

  20. Numerical prediction of fiber orientation in injection-molded short-fiber/thermoplastic composite parts with experimental validation

    SciTech Connect

    Thi, Thanh Binh Nguyen; Morioka, Mizuki; Yokoyama, Atsushi; Hamanaka, Senji; Yamashita, Katsuhisa; Nonomura, Chisato

    2015-05-22

    Numerical prediction of the fiber orientation in the short-glass fiber (GF) reinforced polyamide 6 (PA6) composites with the fiber weight concentration of 30%, 50%, and 70% manufactured by the injection molding process is presented. And the fiber orientation was also directly observed and measured through X-ray computed tomography. During the injection molding process of the short-fiber/thermoplastic composite, the fiber orientation is produced by the flow states and the fiber-fiber interaction. Folgar and Tucker equation is the well known for modeling the fiber orientation in a concentrated suspension. They included into Jeffrey’s equation a diffusive type of term by introducing a phenomenological coefficient to account for the fiber-fiber interaction. Our developed model for the fiber-fiber interaction was proposed by modifying the rotary diffusion term of the Folgar-Tucker equation. This model was presented in a conference paper of the 29{sup th} International Conference of the Polymer Processing Society published by AIP conference proceeding. For modeling fiber interaction, the fiber dynamic simulation was introduced in order to obtain a global fiber interaction coefficient, which is sum function of the fiber concentration, aspect ratio, and angular velocity. The fiber orientation is predicted by using the proposed fiber interaction model incorporated into a computer aided engineering simulation package C-Mold. An experimental program has been carried out in which the fiber orientation distribution has been measured in 100 x 100 x 2 mm injection-molded plate and 100 x 80 x 2 mm injection-molded weld by analyzed with a high resolution 3D X-ray computed tomography system XVA-160α, and calculated by X-ray computed tomography imaging. The numerical prediction shows a good agreement with experimental validation. And the complex fiber orientation in the injection-molded weld was investigated.

  1. Numerical prediction of fiber orientation in injection-molded short-fiber/thermoplastic composite parts with experimental validation

    NASA Astrophysics Data System (ADS)

    Thi, Thanh Binh Nguyen; Morioka, Mizuki; Yokoyama, Atsushi; Hamanaka, Senji; Yamashita, Katsuhisa; Nonomura, Chisato

    2015-05-01

    Numerical prediction of the fiber orientation in the short-glass fiber (GF) reinforced polyamide 6 (PA6) composites with the fiber weight concentration of 30%, 50%, and 70% manufactured by the injection molding process is presented. And the fiber orientation was also directly observed and measured through X-ray computed tomography. During the injection molding process of the short-fiber/thermoplastic composite, the fiber orientation is produced by the flow states and the fiber-fiber interaction. Folgar and Tucker equation is the well known for modeling the fiber orientation in a concentrated suspension. They included into Jeffrey's equation a diffusive type of term by introducing a phenomenological coefficient to account for the fiber-fiber interaction. Our developed model for the fiber-fiber interaction was proposed by modifying the rotary diffusion term of the Folgar-Tucker equation. This model was presented in a conference paper of the 29th International Conference of the Polymer Processing Society published by AIP conference proceeding. For modeling fiber interaction, the fiber dynamic simulation was introduced in order to obtain a global fiber interaction coefficient, which is sum function of the fiber concentration, aspect ratio, and angular velocity. The fiber orientation is predicted by using the proposed fiber interaction model incorporated into a computer aided engineering simulation package C-Mold. An experimental program has been carried out in which the fiber orientation distribution has been measured in 100 x 100 x 2 mm injection-molded plate and 100 x 80 x 2 mm injection-molded weld by analyzed with a high resolution 3D X-ray computed tomography system XVA-160α, and calculated by X-ray computed tomography imaging. The numerical prediction shows a good agreement with experimental validation. And the complex fiber orientation in the injection-molded weld was investigated.

  2. Visualization analysis of tiger-striped flow mark generation phenomena in injection molding

    NASA Astrophysics Data System (ADS)

    Owada, Shigeru; Yokoi, Hidetoshi

    2016-03-01

    The generation mechanism of tiger-striped flow marks of polypropylene (PP)/rubber/talc blends in injection molding was investigated by dynamic visualization analysis in a glass-inserted mold. The analysis revealed that the behavior of the melt flow front correlates with the flow mark generation. The cloudy part in the tiger-striped flow marks corresponded to the low transcription rate area of the melt diverging near the cavity wall, while the glossy part corresponded to the high transcription rate area of the melt converging toward the cavity wall side. The melt temperature at the high transcription rate area was slightly lower than that at the low transcription rate area. These phenomena resulted due to the difference in the temperature of the melt front that was caused by the asymmetric fountain flow. These results suggest the followings; At the moment when the melt is broken near the one side of cavity wall due to piling the extensional strains up to a certain level, the melt spurts out near the broken side. It results in generating asymmetric fountain flow temporarily to relax the extensional front surface, which moves toward the opposite side to form the high transcription area.

  3. Simulation of Orientation in Injection Molding of High Aspect Ratio Particle Thermoplastic Composites

    NASA Astrophysics Data System (ADS)

    Vélez-García, Gregorio M.; Ortman, Kevin C.; Eberle, Aaron P. R.; Wapperom, Peter; Baird, Donald G.

    2008-07-01

    A 2D coupled Hele-Shaw flow approximation for predicting the flow-induced orientation of high aspect ratio particles in injection molded composite parts is presented. For a highly concentrated short glass fiber PBT suspension, the impact of inter-particle interactions and the orientation at the gate is investigated for a center-gated disk using material parameters determined from rheometry. Experimental orientation is determined from confocal laser micrographs using the methods of ellipses. The constitutive equations are discretized using discontinuous Galerkin Finite Elements. Model predictions are significantly improved by using a localized orientation measured experimentally at the gate region instead of random or averaged gapwise measured orientation assumed in previous studies. The predicted profile in different radial positions can be related to the layered structure along the gapwise direction. Model modifications including interactions have lower impact than the initial conditions.

  4. Using injection molding and reversible bonding for easy fabrication of magnetic cell trapping and sorting devices

    NASA Astrophysics Data System (ADS)

    Royet, David; Hériveaux, Yoann; Marchalot, Julien; Scorretti, Riccardo; Dias, André; Dempsey, Nora M.; Bonfim, Marlio; Simonet, Pascal; Frénéa-Robin, Marie

    2017-04-01

    Magnetism and microfluidics are two key elements for the development of inexpensive and reliable tools dedicated to high-throughput biological analysis and providing a large panel of applications in domains ranging from fundamental biology to medical diagnostics. In this work, we introduce a simple protocol, relying on injection molding and reversible bonding for fabrication of magnetic cell trapping and sorting devices using only standard soft-lithography equipment. Magnetic strips or grids made of Polydimethylsiloxane (PDMS) doped with hard (NdFeB) or soft (carbonyl iron) magnetic powders were integrated at the bottom of whole PDMS chips. Preliminary results show the effective deviation/trapping of magnetic beads or magnetically-labeled bacteria as the sample flows through the microchannel, proving the potential of this rapid prototyping approach for easy fabrication of magnetic cell sorters.

  5. Plasmonic gold nanostars as optical nano-additives for injection molded polymer composites.

    PubMed

    Boyne, Devon A; Orlicki, Joshua A; Walck, Scott D; Savage, Alice M; Li, Thomas; Griep, Mark H

    2017-10-06

    Nanoscale engineering of noble metal particles has provided numerous material configurations to selectively confine and manipulate light across the electromagnetic spectrum. Transitioning these materials to a composite form while maintaining the desired resonance properties has proven challenging. In this work, the successful integration of plasmon-focusing gold nanostars (GNSs) into polymer nanocomposites (PNCs) is demonstrated. Tailored GNSs are produced with over a 90% yield and methods to control the branching structures are shown. A protective silica capping shell is employed on the nanomaterials to facilitate survivability in the high temperate/high shear processing parameters to create optically-tuned injection molded PNCs. The developed GNS PNCs possess dichroic scattering and absorption behavior, opening up potential applications in the fields of holographic imaging, optical filtering and photovoltaics.

  6. End Uses Mechanical Properties Settled By The Modified Sintering Conditions Of The Metal Injection Molding Process

    NASA Astrophysics Data System (ADS)

    Marray, Tarek; Jaccquet, Philippe; Moinard-Checot, Delphine; Fabre, Agnès; Barrallier, Laurent

    2011-01-01

    Most common mechanical applications require parts with specific properties as hard faced features. It is well known that treating parts under suitable atmospheres may improve hardness and strength yield of steels. Heat treatment process and more particularly thermo-chemical diffusion processes (such as carburizing or its variation: carbonitriding) can be performed to reach the industrial hardness profile requirements. In this work, a low-alloyed steel feedstock based on water soluble binder system is submitted to the MIM process steps (including injection molding, debinding and sintering). As-sintered parts are then treated under a low pressure carbonitriding treatment. This contribution focuses on preliminary results such as microstructural analyses and mechanical properties which are established at each stage of the process to determine and monitor changes.

  7. Thermal debinding modeling of mass transport and deformation in powder-injection molding compact

    NASA Astrophysics Data System (ADS)

    Shengjie, Ying; Lam, Y. C.; Yu, S. C. M.; Tam, K. C.

    2002-06-01

    A two-dimensional model of mass transport and deformation in thermal debinding for the powder-injection molding (PIM) compact, based on mass and heat transfer in deformable porous media and elasticity theory, is proposed. The primary mechanisms of mass transport, i.e., liquid flow, gas flow, vapor diffusion, and convection, as well as heat transfer, polymer pyrolysis, powder-particle packing, compact deformation, and their interactions are simultaneously included in the model. A computer code, in which integrated control-volume finite-difference and finite-element methods are employed, is developed to simulate the process. The simulated results revealed that the nonuniform distribution of polymer residue, which results from the nonuniform flow of the polymer, causes the nonuniform deformation in the compact. Severe nonuniform deformation in the compact might lead to cracking, distortion, and failure of the compact during the polymer-removal process.

  8. End Uses Mechanical Properties Settled By The Modified Sintering Conditions Of The Metal Injection Molding Process

    SciTech Connect

    Marray, Tarek; Jaccquet, Philippe; Moinard-Checot, Delphine; Fabre, Agnes; Barrallier, Laurent

    2011-01-17

    Most common mechanical applications require parts with specific properties as hard faced features. It is well known that treating parts under suitable atmospheres may improve hardness and strength yield of steels. Heat treatment process and more particularly thermo-chemical diffusion processes (such as carburizing or its variation: carbonitriding) can be performed to reach the industrial hardness profile requirements. In this work, a low-alloyed steel feedstock based on water soluble binder system is submitted to the MIM process steps (including injection molding, debinding and sintering). As-sintered parts are then treated under a low pressure carbonitriding treatment. This contribution focuses on preliminary results such as microstructural analyses and mechanical properties which are established at each stage of the process to determine and monitor changes.

  9. Qualification Methods of Al2O3 Injection Molding Raw Materials

    NASA Astrophysics Data System (ADS)

    Egész, Á.; Gömze, L. A.

    2015-04-01

    For producing ceramic arc tube parts (plugs), there are used two different major components for producing injection molding raw material (feedstock): high purity alumina powder as the main component, and an organic paraffin wax as a binder material. It is expressly important to know the material, physical and chemical properties of these components, since mainly these have effect on the homogenity of feedstock, and therefore on the quality of end product. In this research, both of the main components and the moldable raw material was investigated by visual, physical, and thermal methods. As most important and main statement, the researchers found that the dynamic viscosity of raw material depends more on the applied temperature, than on the deformation speed gradient. Applied analitycal methods were laser granulometry, sieve analysis, differential thermal analysis and rheology analysis.

  10. Research on properties of carbon black/polypropylene composites by dynamic injection molding

    NASA Astrophysics Data System (ADS)

    Wu, Ming-Chun; He, Guang-Jian; Huang, Zhao-Xia; Zhou, Li-Ying; He, He-Zhi

    2016-03-01

    Polymer composites filled with conductive carbon black (CB) are gaining popularity for electromagnetic shielding applications. Dynamic injection molding method was adopted to study the influences of vibration force field on electrical properties of polypropylene/CB composites. The results showed that the percolation phenomenon of conductivity of composites occurred at 15wt% and the calculated SE was positive correlated with the variation trend of conductivity. The calculated SE of composite was more than 30dB at a CB concentration of 30wt%, which could obtain good shielding effects. The result could offer optimum vibration parameters for producing electromagnetic shielding composites by respectively changing the amplitudes and frequencies of the vibration force field.

  11. Biodegradability of injection molded bioplastic pots containing polylactic acid and poultry feather fiber.

    PubMed

    Ahn, H K; Huda, M S; Smith, M C; Mulbry, W; Schmidt, W F; Reeves, J B

    2011-04-01

    The biodegradability of three types of bioplastic pots was evaluated by measuring carbon dioxide produced from lab-scale compost reactors containing mixtures of pot fragments and compost inoculum held at 58 °C for 60 days. Biodegradability of pot type A (composed of 100% polylactic acid (PLA)) was very low (13 ± 3%) compared to literature values for other PLA materials. Near infrared spectroscopy (NIRS) results suggest that the PLA undergoes chemical structural changes during polymer extrusion and injection molding. These changes may be the basis of the low biodegradability value. Biodegradability of pot types B (containing 5% poultry feather, 80% PLA, 15% starch), and C (containing 50% poultry feather, 25% urea, 25% glycerol), were 53 ± 2% and 39 ± 3%, respectively. More than 85% of the total biodegradation of these bioplastics occurred within 38 days. NIRS results revealed that poultry feather was not degraded during composting.

  12. Plasmonic gold nanostars as optical nano-additives for injection molded polymer composites

    NASA Astrophysics Data System (ADS)

    Boyne, Devon A.; Orlicki, Joshua A.; Walck, Scott D.; Savage, Alice M.; Li, Thomas; Griep, Mark H.

    2017-10-01

    Nanoscale engineering of noble metal particles has provided numerous material configurations to selectively confine and manipulate light across the electromagnetic spectrum. Transitioning these materials to a composite form while maintaining the desired resonance properties has proven challenging. In this work, the successful integration of plasmon-focusing gold nanostars (GNSs) into polymer nanocomposites (PNCs) is demonstrated. Tailored GNSs are produced with over a 90% yield and methods to control the branching structures are shown. A protective silica capping shell is employed on the nanomaterials to facilitate survivability in the high temperate/high shear processing parameters to create optically-tuned injection molded PNCs. The developed GNS PNCs possess dichroic scattering and absorption behavior, opening up potential applications in the fields of holographic imaging, optical filtering and photovoltaics.

  13. Evaluation of the rigidity of dentures made of injection-molded materials.

    PubMed

    Wadachi, Juro; Sato, Masayuki; Igarashi, Yoshimasa

    2013-01-01

    Dentures made of 2 different types of injection-molded thermoplastic resins (polyamide resin and polyester resin) and a denture made of conventional heat-polymerized resin were used to create an experimental model of a mandibular molar region with a two-tooth gap. In the experimental model, a force of 100 N was applied onto the mesial fossa of the first molars of the dentures, and comparisons were performed by measuring the pressure applied under the denture base and the subsidence rate of the denture. The polyamide resin denture showed the highest subsidence, exerted the highest pressure on the underlying mucosa, and showed significant differences with the other types of dentures. The findings showed that polyamide resins have the lowest degree of elasticity, and that when resins with such low elasticities are used in the denture base, they should preferably be reinforced with metals.

  14. Image-guided tissue engineering of anatomically shaped implants via MRI and micro-CT using injection molding.

    PubMed

    Ballyns, Jeffery J; Gleghorn, Jason P; Niebrzydowski, Vicki; Rawlinson, Jeremy J; Potter, Hollis G; Maher, Suzanne A; Wright, Timothy M; Bonassar, Lawrence J

    2008-07-01

    This study demonstrates for the first time the development of engineered tissues based on anatomic geometries derived from widely used medical imaging modalities such as computed tomography (CT) and magnetic resonance imaging (MRI). Computer-aided design and tissue injection molding techniques have demonstrated the ability to generate living implants of complex geometry. Due to its complex geometry, the meniscus of the knee was used as an example of this technique's capabilities. MRI and microcomputed tomography (microCT) were used to design custom-printed molds that enabled the generation of anatomically shaped constructs that retained shape throughout 8 weeks of culture. Engineered constructs showed progressive tissue formation indicated by increases in extracellular matrix content and mechanical properties. The paradigm of interfacing tissue injection molding technology can be applied to other medical imaging techniques that render 3D models of anatomy, demonstrating the potential to apply the current technique to engineering of many tissues and organs.

  15. A wide variety of injection molding technologies is now applicable to small series and mass production

    SciTech Connect

    Bloß, P. E-mail: juettner@kuz-leipzig.de E-mail: loeser@kuz-leipzig.de E-mail: krajewsky@kuz-leipzig.de; Jüttner, G. E-mail: juettner@kuz-leipzig.de E-mail: loeser@kuz-leipzig.de E-mail: krajewsky@kuz-leipzig.de; Jacob, S. E-mail: juettner@kuz-leipzig.de E-mail: loeser@kuz-leipzig.de E-mail: krajewsky@kuz-leipzig.de; Löser, C. E-mail: juettner@kuz-leipzig.de E-mail: loeser@kuz-leipzig.de E-mail: krajewsky@kuz-leipzig.de; Michaelis, J. E-mail: juettner@kuz-leipzig.de E-mail: loeser@kuz-leipzig.de E-mail: krajewsky@kuz-leipzig.de; Krajewsky, P. E-mail: juettner@kuz-leipzig.de E-mail: loeser@kuz-leipzig.de E-mail: krajewsky@kuz-leipzig.de

    2014-05-15

    Micro plastic parts open new fields for application, e. g., to electronics, sensor technologies, optics, and medical engineering. Before micro parts can go to mass production, there is a strong need of having the possibility for testing different designs and materials including material combinations. Hence, flexible individual technical and technological solutions for processing are necessary. To manufacture high quality micro parts, a micro injection moulding machine named formicaPlast based on a two-step plunger injection technology was developed. Resulting from its design, the residence time and the accuracy problems for managing small shot volumes with reproducible high accuracy are uncompromisingly solved. Due to their simple geometry possessing smooth transitions and non adherent inner surfaces, the plunger units allow to process 'all' thermoplastics from polyolefines to high performance polymers, optical clear polymers, thermally sensitive bioresorbables, highly filled systems (the so-called powder injection molding PIM), and liquid silicon rubber (LSR, here with a special kit). The applied platform strategy in the 1K and 2K version allows integrating automation for assembling, handling and packaging. A perpendicular arrangement allows encapsulation of inserts, also partially, and integration of this machine into process chains. Considering a wide variety of different parts consisting of different materials, the high potential of the technology is demonstrated. Based on challenging industrial parts from electronic applications (2K micro MID and bump mat, where both are highly structured parts), the technological solutions are presented in more detail.

  16. A wide variety of injection molding technologies is now applicable to small series and mass production

    NASA Astrophysics Data System (ADS)

    Bloß, P.; Jüttner, G.; Jacob, S.; Löser, C.; Michaelis, J.; Krajewsky, P.

    2014-05-01

    Micro plastic parts open new fields for application, e. g., to electronics, sensor technologies, optics, and medical engineering. Before micro parts can go to mass production, there is a strong need of having the possibility for testing different designs and materials including material combinations. Hence, flexible individual technical and technological solutions for processing are necessary. To manufacture high quality micro parts, a micro injection moulding machine named formicaPlast based on a two-step plunger injection technology was developed. Resulting from its design, the residence time and the accuracy problems for managing small shot volumes with reproducible high accuracy are uncompromisingly solved. Due to their simple geometry possessing smooth transitions and non adherent inner surfaces, the plunger units allow to process "all" thermoplastics from polyolefines to high performance polymers, optical clear polymers, thermally sensitive bioresorbables, highly filled systems (the so-called powder injection molding PIM), and liquid silicon rubber (LSR, here with a special kit). The applied platform strategy in the 1K and 2K version allows integrating automation for assembling, handling and packaging. A perpendicular arrangement allows encapsulation of inserts, also partially, and integration of this machine into process chains. Considering a wide variety of different parts consisting of different materials, the high potential of the technology is demonstrated. Based on challenging industrial parts from electronic applications (2K micro MID and bump mat, where both are highly structured parts), the technological solutions are presented in more detail.

  17. Microstructure and mechanical behavior of metal injection molded Ti-Nb binary alloys as biomedical material.

    PubMed

    Zhao, Dapeng; Chang, Keke; Ebel, Thomas; Qian, Ma; Willumeit, Regine; Yan, Ming; Pyczak, Florian

    2013-12-01

    The application of titanium (Ti) based biomedical materials which are widely used at present, such as commercially pure titanium (CP-Ti) and Ti-6Al-4V, are limited by the mismatch of Young's modulus between the implant and the bones, the high costs of products, and the difficulty of producing complex shapes of materials by conventional methods. Niobium (Nb) is a non-toxic element with strong β stabilizing effect in Ti alloys, which makes Ti-Nb based alloys attractive for implant application. Metal injection molding (MIM) is a cost-efficient near-net shape process. Thus, it attracts growing interest for the processing of Ti and Ti alloys as biomaterial. In this investigation, metal injection molding was applied to the fabrication of a series of Ti-Nb binary alloys with niobium content ranging from 10wt% to 22wt%, and CP-Ti for comparison. Specimens were characterized by melt extraction, optical microscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and transmission electron microscopy (TEM). Titanium carbide formation was observed in all the as-sintered Ti-Nb binary alloys but not in the as-sintered CP-Ti. Selected area electron diffraction (SAED) patterns revealed that the carbides are Ti2C. It was found that with increasing niobium content from 0% to 22%, the porosity increased from about 1.6% to 5.8%, and the carbide area fraction increased from 0% to about 1.8% in the as-sintered samples. The effects of niobium content, porosity and titanium carbides on mechanical properties have been discussed. The as-sintered Ti-Nb specimens exhibited an excellent combination of high tensile strength and low Young's modulus, but relatively low ductility.

  18. Injection molding of high precision optics for LED applications made of liquid silicone rubber

    SciTech Connect

    Hopmann, Christian; Röbig, Malte

    2016-03-09

    Light Emitting Diodes (LED) conquer the growing global market of lighting technologies. Due to their advantages, they are increasingly used in consumer products, in lighting applications in the home and in the mobility sector as well as in industrial applications. Particularly, with regard to the increasing use of high-power LED (HP-LED) the materials in the surrounding area of the light emitting semiconductor chip are of utmost importance. While the materials behind the semiconductor chip are optimized for maximum heat dissipation, the materials currently used for the encapsulation of the semiconductor chip (primary optics) and the secondary optics encounter their limits due to the high temperatures. In addition certain amounts of blue UV radiation degrade the currently used materials such as epoxy resins or polyurethanes for primary optics. In the context of an ongoing joint research project with various partners from the industry, an innovative manufacturing method for high precision optics for LED applications made of liquid silicone rubber (LSR) is analyzed at the Institut of Plastics Processing (IKV), Aachen. The aim of this project is to utilize the material-specific advantages of high transparent LSR, especially the excellent high temperature resistance and the great freedom in design. Therefore, a high integrated injection molding process is developed. For the production of combined LED primary and secondary optics a LED board is placed in an injection mold and overmolded with LSR. Due to the integrated process and the reduction of subcomponents like the secondary optics the economics of the production process can be improved significantly. Furthermore combined LED optics offer an improved effectiveness, because there are no losses of the light power at the transition of the primary and secondary optics.

  19. 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

  20. Development of polylactide (PLA) and PLA nanocomposite foams in injection molding for automotive applications

    NASA Astrophysics Data System (ADS)

    Najafi Chaloupli, Naqi

    Plastic materials are extensively used in automotive structures since they make cars more energy efficient. Recently, the automotive industry is searching for bio-based and renewable alternatives to petroleum-based plastics to reduce the dependence on fossil fuels. Among polymers originating from renewable sources, polylactide (PLA) has attracted significant interest. The use of this polymer in durable industries is promising. Fuel-efficient automobiles are nowadays demanded due to the increasing concerns about environmental and fuel issues. The automobile fuel efficiency can be improved by using a lightweight material and, thereby, reducing the automobile weight. A potential method to achieve this objective is the use of the foaming technology. Foam is a material where a gas phase is encapsulated by a solid phase. Foaming technology helps to manufacture lightweight parts with superior properties in comparison with their solid counterparts. The basic mechanisms of foaming process normally consists of gas implementation, formation of uniform polymer-gas solution, cell nucleation, cell growth and, finally, cell stabilization. PLA foaming has, however, proved to be difficult mainly due to poor rheological properties, small processing window, and slow crystallization kinetics. The ultimate purpose of this work is to reduce by 30 % the weight of polylactide (PLA)-clay based nanocomposites by manufacturing injection-molded foamed parts. To use standard processing equipment, a chemical blowing agent (CBA) was employed. The injection molding technique was utilized in this project because it is the most widely used fabrication process in industry that can produce complex shaped articles. This process, however, is more challenging than other foaming processes since it deals with many additional controlling parameters. In the first part of this project, we illustrated how long chain branching (LCB) and molecular structure impact the melt rheology, crystallization and batch

  1. Development of an injection molded ethylene-vinyl acetate copolymer (EVA) intravaginal insert for the delivery of progesterone to cattle.

    PubMed

    Cappadoro, A J; Luna, J A

    2015-07-01

    The purpose of this study was to develop a new injection-molded intravaginal insert manufactured from ethylene-vinyl acetate containing progesterone for a 7-day insertion period in cattle. The manufacturing process resulted in a reduction in the residual drug compared to the silicone insert available while still maintaining biological performance.

  2. Serial corneal endothelial cell loss with lathe-cut and injection-molded posterior chamber intraocular lenses.

    PubMed

    Kraff, M C; Sanders, D R; Lieberman, H L

    1983-01-01

    We compared endothelial cell loss of patients implanted with lathe-cut posterior chamber lenses and those implanted with injection-molded lenses over a three-year postoperative period. Results were based on more than 2,500 measurements of corneal endothelial density. Although the technique of cataract extraction (anterior chamber phacoemulsification, posterior chamber phacoemulsification, or planned extracapsular extraction) significantly affected cell loss (P less than .01), the type of implant (lathe-cut or injection-molded) did not. Significant continuing endothelial cell loss did not occur during the first three postoperative years with injection-molded lenses. There was, however, a statistically significant 7% to 15% additional cell loss after surgery over the first two to three postoperative years with lathe-cut implants. There have been no cases of corneal endothelial decompensation developing after implantation of injection-molded or lathe-cut lenses. Because a standard field clinical specular microscope was used in this study, cell counting errors cannot be ruled out as a cause of these findings.

  3. Thermal Properties of Extruded Injection-Molded Polycaprolactone/Gluten Bioblends Characterized by TGA, DSC, SEM and Infrared Photoacoustic Spectroscopy

    USDA-ARS?s Scientific Manuscript database

    In order to determine the degree of compatibility between Polycaprolactone resin (PCL) and vital wheat gluten (VG), PCL was compounded with VG at 90:10, 80:20, 70:30, 60:40, 50:50, and 30:70. The composites were blended by extrusion followed by injection molding. Thermal, morphological, and struct...

  4. Optimizing Injection Molding Parameters of Different Halloysites Type-Reinforced Thermoplastic Polyurethane Nanocomposites via Taguchi Complemented with ANOVA

    PubMed Central

    Gaaz, Tayser Sumer; Sulong, Abu Bakar; Kadhum, Abdul Amir H.; Nassir, Mohamed H.; Al-Amiery, Ahmed A.

    2016-01-01

    Halloysite nanotubes-thermoplastic polyurethane (HNTs-TPU) nanocomposites are attractive products due to increasing demands for specialized materials. This study attempts to optimize the parameters for injection just before marketing. The study shows the importance of the preparation of the samples and how well these parameters play their roles in the injection. The control parameters for injection are carefully determined to examine the mechanical properties and the density of the HNTs-TPU nanocomposites. Three types of modified HNTs were used as untreated HNTs (uHNTs), sulfuric acid treated (aHNTs) and a combined treatment of polyvinyl alcohol (PVA)-sodium dodecyl sulfate (SDS)-malonic acid (MA) (treatment (mHNTs)). It was found that mHNTs have the most influential effect of producing HNTs-TPU nanocomposites with the best qualities. One possible reason for this extraordinary result is the effect of SDS as a disperser and MA as a crosslinker between HNTs and PVA. For the highest tensile strength, the control parameters are demonstrated at 150 °C (injection temperature), 8 bar (injection pressure), 30 °C (mold temperature), 8 min (injection time), 2 wt % (HNTs loading) and mHNT (HNTs type). Meanwhile, the optimized combination of the levels for all six control parameters that provide the highest Young’s modulus and highest density was found to be 150 °C (injection temperature), 8 bar (injection pressure), 32 °C (mold temperature), 8 min (injection time), 3 wt % (HNTs loading) and mHNT (HNTs type). For the best tensile strain, the six control parameters are found to be 160 °C (injection temperature), 8 bar (injection pressure), 32 °C (mold temperature), 8 min (injection time), 2 wt % (HNTs loading) and mHNT (HNTs type). For the highest hardness, the best parameters are 140 °C (injection temperature), 6 bar (injection pressure), 30 °C (mold temperature), 8 min (injection time), 2 wt % (HNTs loading) and mHNT (HNTs type). The analyses are carried out by

  5. Study of micropart fabrication via 17-4 PH stainless nanopowder injection molding.

    PubMed

    Tirta, Andy; Prasetyo, Yus; Baek, Eung-Ryul; Choi, Chul-Jin

    2011-01-01

    Micropart fabrication via 17-4 PH stainless nanopowder injection molding was investigated. The nanopowder was mixed with a binder that was based on wax to produce a feedstock composed of 45% powder and binder (the powder load). Initially, the fit and proper test was done before the micropart was made by making some bars of green samples, which the properties were examined after the sintering process. The examination involved the mechanical properties such as the porosity, hardness, and some of metallurgical aspects, such as the second-phase formation and the final compound after the sintering. The results showed that utilizing 17-4 PH stainless nanopowder is promising for micropart fabrication since it can form a nearly full-density sintered sample with a low porosity and good toughness, and can provide a smooth surface finish. After this, the investigations followed with the injection of the feedstock into the PDMS micromold that was formed by the nickel pattern from the X-Ray LIGA process. The green samples successfully produced a high-aspect-ratio sample with a thickness of up to 1 mm and an aspect ratio of 15 in the microchannel part. Then the green samples were sintered at 1,300 degrees C for 2 h, since from the initial test, they showed optimum parameters with nearly full density, low porosity, and a high degree of hardness. The research shows the excellent results of the application of the 17-4 PH stainless nanopowder to micropart fabrication.

  6. Design and development of an injection-molded demultiplexer for optical communication systems in the visible range.

    PubMed

    Höll, S; Haupt, M; Fischer, U H P

    2013-06-20

    Optical simulation software based on the ray-tracing method offers easy and fast results in imaging optics. This method can also be applied in other fields of light propagation. For short distance communications, polymer optical fibers (POFs) are gradually gaining importance. This kind of fiber offers a larger core diameter, e.g., the step index POF features a core diameter of 980 μm. Consequently, POFs have a large number of modes (>3 million modes) in the visible range, and ray tracing could be used to simulate the propagation of light. This simulation method is applicable not only for the fiber itself but also for the key components of a complete POF network, e.g., couplers or other key elements of the transmission line. In this paper a demultiplexer designed and developed by means of ray tracing is presented. Compared to the classical optical design, requirements for optimal design differ particularly with regard to minimizing the insertion loss (IL). The basis of the presented key element is a WDM device using a Rowland spectrometer setup. In this approach the input fiber carries multiple wavelengths, which will be divided into multiple output fibers that transmit only one wavelength. To adapt the basic setup to POF, the guidance of light in this element has to be changed fundamentally. Here, a monolithic approach is presented with a blazed grating using an aspheric mirror to minimize most of the aberrations. In the simulations the POF is represented by an area light source, while the grating is analyzed for different orders and the highest possible efficiency. In general, the element should be designed in a way that it can be produced with a mass production technology like injection molding in order to offer a reasonable price. However, designing the elements with regard to injection molding leads to some inherent challenges. The microstructure of an optical grating and the thick-walled 3D molded parts both result in high demands on the injection molding

  7. Multiple-Step Injection Molding for Fibrin-Based Tissue-Engineered Heart Valves

    PubMed Central

    Weber, Miriam; Gonzalez de Torre, Israel; Moreira, Ricardo; Frese, Julia; Oedekoven, Caroline; Alonso, Matilde; Rodriguez Cabello, Carlos J.

    2015-01-01

    Heart valves are elaborate and highly heterogeneous structures of the circulatory system. Despite the well accepted relationship between the structural and mechanical anisotropy and the optimal function of the valves, most approaches to create tissue-engineered heart valves (TEHVs) do not try to mimic this complexity and rely on one homogenous combination of cells and materials for the whole construct. The aim of this study was to establish an easy and versatile method to introduce spatial diversity into a heart valve fibrin scaffold. We developed a multiple-step injection molding process that enables the fabrication of TEHVs with heterogeneous composition (cell/scaffold material) of wall and leaflets without the need of gluing or suturing components together, with the leaflets firmly connected to the wall. The integrity of the valves and their functionality was proved by either opening/closing cycles in a bioreactor (proof of principle without cells) or with continuous stimulation over 2 weeks. We demonstrated the potential of the method by the two-step molding of the wall and the leaflets containing different cell lines. Immunohistology after stimulation confirmed tissue formation and demonstrated the localization of the different cell types. Furthermore, we showed the proof of principle fabrication of valves using different materials for wall (fibrin) and leaflets (hybrid gel of fibrin/elastin-like recombinamer) and with layered leaflets. The method is easy to implement, does not require special facilities, and can be reproduced in any tissue-engineering lab. While it has been demonstrated here with fibrin, it can easily be extended to other hydrogels. PMID:25654448

  8. Injection Molding Simulation : Taking Into Account the Process History to Predict the Anisotropy in the End-Use Properties

    NASA Astrophysics Data System (ADS)

    Silva, Luisa; Miled, Houssem; Laure, Patrice; Coupez, Thierry

    2007-05-01

    This work's context is an industrial project aiming the accurate modeling of the injection molding process. 3D numerical simulation of the different stages is considered: during processing, anisotropy of the stress state build up affects its mechanical, optical or dimensional properties, and induces warpage once the part is ejected. A first example of injection molding of reinforced thermoplastics will be treated. In this case, we will consider that during the injection step, an orientation will be induced by the flow. Furthermore, the thermoplastic matrix will pass from the liquid to the solid state, and orientation and stresses will remain frozen. Evolution of orientation or extra stress is computed using the Folgar and Tucker equation, with continuous or discontinuous approximations. Results are obtained in a 3D complex industrial part.

  9. The evaluation of vacuum venting and variotherm process for improving the replication by injection molding of high aspect ratio micro features for biomedical application

    NASA Astrophysics Data System (ADS)

    Sorgato, Marco; Lucchetta, Giovanni

    2015-05-01

    The aspect ratio achievable in replicating micro features is one of the most important process characteristics and it is a major manufacturing constraint in applying injection molding in a range of micro engineering applications. Vacuum venting has been reported to be an effective technique in replicating micro features by microinjection molding. High surface-to-volume ratio and reduced dimensions of micro parts promote the instantaneous drop of melt temperature and consequently lead to incomplete filling. This study aims to investigate the effects of variotherm process, cavity evacuation and their interaction on the production of a micro fluidic filter for biomedical applications. A low-viscosity polystyrene and a cyclic olefin copolymer were molded applying a combination of mold evacuation and a rapid mold temperature variation that keeps the cavity temperature above the glass transition temperature during the injection phase. The research revealed the importance of these molding technologies in enhancing part filling and the replication quality for high aspect ratio micro features.

  10. Influence of injection gate definition on the flow-front approximation in numerical simulations of mold-filling processes

    NASA Astrophysics Data System (ADS)

    Modi, Dhiren; Imáek, Pavel; Advani, Suresh

    2003-08-01

    Flow through porous media has been used to model resin impregnation in composites manufacturing processes such as resin transfer molding. Many numerical schemes have been used to explore the efficiency and accuracy in description of the movement of the liquid front when it is introduced through injection gates into a mold containing stationary and compacted fibrous porous media. In all numerical schemes, injection gates are modelled with a single node. Mathematically, a single node definition for a finite radius injection gate imparts a singularity. In this paper, an approach to avoid this singularity by modelling the injection gate with more than one node is presented. An analytical solution relating the fill time to the injection gate radius is developed for a constant pressure injection from a spherical injection gate into an isotropic media. A new parameter mesh density level, defined as the ratio of the injection radius to the element size, is used to investigate the accuracy and the convergence of the numerical results. It is shown that the numerical results converge when the mesh density level is increased. The accuracy of the results depends on the ratio of the flow-front radius to the injection gate radius as well as on the mesh density level. In many situations, a spherical injection gate may not represent the correct physics and model simplification may be necessary.The impact of such simplifications is also quantified. The systematic analysis presented in this paper should prove useful to the modeller in taking the decision whether to select the proper, geometric definition for the injection gate to obtain accurate results or to define the injection gate using a single node and be aware of the errors introduced due to the singularity.

  11. Effect of boron addition on injection molded 316L stainless steel: mechanical, corrosion properties and in vitro bioactivity.

    PubMed

    Bayraktaroglu, Esra; Gulsoy, H Ozkan; Gulsoy, Nagihan; Er, Ozay; Kilic, Hasan

    2012-01-01

    The research was investigated the effect of boron additions on sintering characteristics, mechanical, corrosion properties and biocompatibility of injection molded austenitic grade 316L stainless steel. Addition of boron is promoted to get high density of sintered 316L stainless steels. The amount of boron plays a role in determining the sintered microstructure and all properties. In this study, 316L stainless steel powders have been used with the elemental NiB powders. A feedstock containing 62.5 wt% powders loading was molded at different injection molded temperature. The binders were completely removed from molded components by solvent and thermal debinding at different temperature. The debinded samples were sintered at different temperature for 60 min. Mechanical property, microstructural characterization and electrochemical property of the sintered samples were performed using tensile testing, hardness, optical, scanning electron microscopy and electrochemical corrosion experiments. Sintered samples were immersed in a simulated body fluid (SBF) with elemental concentrations that were comparable to those of human blood plasma for a total period of 15 days. Both materials were implanted in fibroblast culture for biocompatibility evaluations were carried out. Results of study showed that sintered 316L and 316L with NiB addition samples exhibited high mechanical and corrosion properties in a physiological environment. Especially, 316L with NiB addition can be used in some bioapplications.

  12. Metallurgical characterization of orthodontic brackets produced by Metal Injection Molding (MIM).

    PubMed

    Zinelis, Spiros; Annousaki, Olga; Makou, Margarita; Eliades, Theodore

    2005-11-01

    The aim of this study was to investigate the bonding base surface morphology, alloy type, microstructure, and hardness of four types of orthodontic brackets produced by Metal Injection Molding technology (Discovery, Extremo, Freedom, and Topic). The bonding base morphology of the brackets was evaluated by scanning electron microscopy (SEM). Brackets from each manufacturer were embedded in epoxy resin, and after metallographic grinding, polishing and coating were analyzed by x-ray energy-dispersive spectroscopic (EDS) microanalysis to assess their elemental composition. Then, the brackets were subjected to metallographic etching to reveal their metallurgical structure. The same specimen surfaces were repolished and used for Vickers microhardness measurements. The results were statistically analyzed with one-way analysis of variance and Student-Newman-Keuls multiple comparison test at the 0.05 level of significance. The findings of SEM observations showed a great variability in the base morphology design among the brackets tested. The x-ray EDS analysis demonstrated that each bracket was manufactured from different ferrous or Co-based alloys. Metallographic analysis showed the presence of a large grain size for the Discovery, Freedom, and Topic brackets and a much finer grain size for the Extremo bracket. Vickers hardness showed great variations among the brackets (Topic: 287 +/- 16, Freedom: 248 +/- 13, Discovery: 214 +/- 12, and Extremo: 154 +/- 9). The results of this study showed that there are significant differences in the base morphology, composition, microstructure, and microhardness among the brackets tested, which may anticipate significant clinical implications.

  13. Ceramic micro-injection molded nozzles for serial femtosecond crystallography sample delivery

    SciTech Connect

    Beyerlein, K. R.; Adriano, L.; Heymann, M.; Kirian, R.; Knoska, J.; Wilde, F.; Chapman, H. N.; Bajt, S.

    2015-12-08

    Serial femtosecond crystallography (SFX) using X-ray Free-Electron Lasers (XFELs) allows for room temperature protein structure determination without evidence of conventional radiation damage. In this method, a liquid suspension of protein microcrystals can be delivered to the X-ray beam in vacuum as a micro-jet, which replenishes the crystals at a rate that exceeds the current XFEL pulse repetition rate. Gas dynamic virtual nozzles produce the required micrometer-sized streams by the focusing action of a coaxial sheath gas and have been shown to be effective for SFX experiments. Here, we describe the design and characterization of such nozzles assembled from ceramic micro-injection molded outer gas-focusing capillaries. Trends of the emitted jet diameter and jet length as a function of supplied liquid and gas flow rates are measured by a fast imaging system. The observed trends are explained by derived relationships considering choked gas flow and liquidflow conservation. In conclusion, the performance of these nozzles in a SFX experiment is presented, including an analysis of the observed background.

  14. Comparative study of pore structure evolution during solvent and thermal debinding of powder injection molded parts

    SciTech Connect

    Hwang, K.S.; Hsieh, Y.M.

    1996-02-01

    The solvent debinding process has been widely accepted in the powder injection molding (PIM) industry due to its short debinding cycle. In the current study, specimens were immersed in a heptane bath for different lengths of time, and the pore structure evolvement in the compact was analyzed. Mercury porosimetry analyses and scanning electron micrographs showed that the binder extraction started from the surface and progressed toward the center of the compacts. As the debinding continued, the pores grew and were widely distributed in size. This pore structure evolvement was different from that of straight thermal debinding in which the pore size distribution was quite narrow and the mean pore diameter shifted toward smaller sizes as debinding time increased. After the soluble binders were extracted, parts were subjected to a subsequent thermal debinding during which these pores served as conduits for decomposed gas to escape. Concurrently, the remaining binder became fluidlike and was redistributed within the compact due to capillarity. This pore structure, as observed from the mercury intrusion curves, showed a sharp increase in the pore volume at the 0.8-{micro}m size, followed by a series of fine pores, which is different from the pore structure of straight thermal debinding. The difference in the pore structure evolvement between solvent and thermal debinding and its effect on the debinding rate are discussed.

  15. Characterization and performance of injection molded poly(methylmethacrylate) microchips for capillary electrophoresis.

    PubMed

    Nikcevic, Irena; Lee, Se Hwan; Piruska, Aigars; Ahn, Chong H; Ridgway, Thomas H; Limbach, Patrick A; Wehmeyer, K R; Heineman, William R; Seliskar, Carl J

    2007-06-22

    Injection molded poly(methylmethacrylate) (IM-PMMA), chips were evaluated as potential candidates for capillary electrophoresis disposable chip applications. Mass production and usage of plastic microchips depends on chip-to-chip reproducibility and on analysis accuracy. Several important properties of IM-PMMA chips were considered: fabrication quality evaluated by environmental scanning electron microscope imaging, surface quality measurements, selected thermal/electrical properties as indicated by measurement of the current versus applied voltage (I-V) characteristic and the influence of channel surface treatments. Electroosmotic flow was also evaluated for untreated and O2 reactive ion etching (RIE) treated surface microchips. The performance characteristics of single lane plastic microchip capillary electrophoresis (MCE) separations were evaluated using a mixture of two dyes-fluorescein (FL) and fluorescein isothiocyanate (FITC). To overcome non-wettability of the native IM-PMMA surface, a modifier, polyethylene oxide was added to the buffer as a dynamic coating. Chip performance reproducibility was studied for chips with and without surface modification via the process of RIE with O2 and by varying the hole position for the reservoir in the cover plate or on the pattern side of the chip. Additionally, the importance of reconditioning steps to achieve optimal performance reproducibility was also examined. It was found that more reproducible quantitative results were obtained when normalized values of migration time, peak area and peak height of FL and FITC were used instead of actual measured parameters.

  16. Foam injection molding of polypropylene/stainless steel fiber composites for efficient EMI shielding

    NASA Astrophysics Data System (ADS)

    Ameli, A.; Nofar, M.; Saniei, M.; Wang, S.; Park, C. B.

    2016-03-01

    Lightweight polypropylene/stainless-steel fiber (PP-SSF) composites with 15-35% density reduction were fabricated using foam injection molding and supercritical carbon dioxide (CO2). The electrical percolation threshold, through-plane electrical conductivity, and electromagnetic interference (EMI) shielding effectiveness (SE) of the PP-SSF composite foams were characterized and compared against the solid samples. The effects of the plasticizing gas and the void fraction on fiber breakage and orientation were also investigated. Microstructure characterization showed that the presence of dissolved CO2 decreased fiber breakage by about 30%, and together with foaming action, contributed to less preferential orientation of fibers. Consequently, the percolation threshold decreased up to four folds from 0.85 to 0.21 vol.% as the void fraction increased from 0 to 35%. The specific EMI SE was also significantly enhanced. A maximum specific EMI SE of 75 dB.g-1cm3 was achieved in PP-1.1 vol.% SSF composite foams, which was highly superior to 38 dB.g-1cm3 of the solid PP-1.0 vol.% SSF composites. The results reveal that light and efficient products with a lower fiber content can be developed by foam for EMI shielding applications.

  17. Trial production of titanium orthodontic brackets fabricated by metal injection molding (MIM) with sintering.

    PubMed

    Deguchi, T; Ito, M; Obata, A; Koh, Y; Yamagishi, T; Oshida, Y

    1996-07-01

    Safety and esthetics are two indispensable factors to consider when fabricating orthodontic brackets. However, these factors are not easily achieved when conventional techniques (including forging and casting) are used in the mass production of titanium brackets, albeit the brackets exhibit excellent biocompatibility. In the present study, orthodontic brackets were manufactured by metal powder injection molding with sintering. Brackets with three different base designs were made and subjected to compression shear tests for evaluation of their bonding strength to enamel substrate. The shapes given to the dimple of the base were spherical, oval, and grooved. The maximum shear forces for each type were 11.1 kgf, 7.6 kgf, and 18.5 kgf, respectively. The bonding strengths of the titanium bracket were equivalent to those obtained with conventional stainless steel brackets. Moreover, uniform distribution of Vickers hardness values (average, 240 +/- 40 Hv) measured at three locations indicated that the titanium bracket was uniformly sintered. Accordingly, titanium brackets thus fabricated exhibit a potential for clinical application.

  18. Sintering Behavior and Microstructure Formation of Titanium Aluminide Alloys Processed by Metal Injection Molding

    NASA Astrophysics Data System (ADS)

    Soyama, Juliano; Oehring, Michael; Ebel, Thomas; Kainer, Karl Ulrich; Pyczak, Florian

    2017-04-01

    The sintering behavior of metal injection molded titanium aluminide alloys, their microstructure formation and resulting mechanical properties were investigated. As reference material, the alloy Ti-45Al-5Nb-0.2B-0.2C at.% (TNB-V5) was selected. Additionally, two other variations with Mo and Mo + Si additions were prepared: Ti-45Al-3Nb-1Mo-0.2B-0.2C at.% and Ti-45Al-3Nb-1Mo-1Si-0.2B-0.2C at.%. The results indicate that the optimum sintering temperature was slightly above the solidus line. With proper sintering parameters, very low porosities (<0.5%) and fine microstructures with a colony size <85 µm could be achieved. Considering the sintering temperatures applied, the phase transformations upon cooling could be described as L + β → β → α + β → α → α + γ → α2 + γ, which was in agreement with the microstructures observed. The effects of Mo and Si were opposite regarding the sintering behavior. Mo addition led to an increase in the optimum sintering temperature, whereas Si caused a significant decrease.

  19. Simulation of polymer removal from a powder injection molding compact by thermal debinding

    NASA Astrophysics Data System (ADS)

    Lam, Y. C.; Yu, S. C. M.; Tam, K. C.; Shengjie, Ying

    2000-10-01

    Powder injection molding (PIM) is an important net-shape manufacturing process. Thermal debinding is a common methodology for the final removal of residual polymer from a PIM compact prior to sintering. This process is an intricate combination of evaporation, liquid and gas migration, pyrolysis of polymer, and heat transfer in porous media. A better understanding of thermal debinding could lead to optimization of the process to prevent the formation of defects. Simulation of the process based on an integrated mathematical model for mass and heat transfer in porous media is proposed. The mechanisms of mass transport, i.e., liquid flow, gas flow, vapor diffusion, and convection, as well as the phase transitions of polymer, and their interactions, are included in the model. The macroscopic partial differential equations are formulated by volume averaging of the microscopic conservation laws. The basic equations consist of mass conservation and energy conservation and are solved numerically. Polymer residue, pressure, and temperature distributions are predicted. The importance of the various mass transfer mechanisms is evaluated. The effects of key mass transfer parameters on thermal debinding are discussed. It is revealed from the results that the assumed binder front, which is supposed to recede into the powder compact as removal progresses, does not exist. The mass flux of polymer liquid is of the same order of the mass flux of polymer vapor in the gas phase, and the polymer vapor diffusion in the liquid phase is negligible.

  20. Development, Strength and Functional Evaluation of Plastic Microneedle Array Fabricated by Injection Molding

    NASA Astrophysics Data System (ADS)

    Yoshimura, Chisato; Ishikawa, Hiroyuki; Furuta, Shinji; Aoki, Hikoharu; Sugiyama, Susumu

    We hereby fabricated the microneedle arrays whose dimensions of 300 μm in height, 100 and 150 μm in diagonal lengths of bottom surface and with densities of 900 and 4,400 needles/ cm2 by injection molding. The resist patterns were pre-formed by three-dimensional fine manufacturing with movable resist during the exposure in LIGA process. Polylactic acid was used for microneedle arrays in consideration of the prospective medical use in transdermal methods and the like. Our study was to evaluate the material filling of the needle tips and dermal penetrability. The flexibility of the needle tips was also tested by the force added to the tips, and its result was compared with the analysis of flexibility by CAE; computer aided experiment. The resin filling did not reach to the deepest point of the Ni stamper, and the filling remained within the range of 12 to 17 μm in diameter. However, the penetration rate on pig skin with the density of 900 needles / cm2 resulted in the range of 60 to 80%, and this result represented the satisfactory capability of dermal penetration in spite of the previously described needle tip dimensions of microneedle array. Closely resembling needle flexibility to its analysis proved that CAE analysis on the strength of microstructures was well effective.

  1. Fabrication of a Ti porous microneedle array by metal injection molding for transdermal drug delivery

    PubMed Central

    Li, Jiyu; Liu, Bin; Zhou, Yingying; Chen, Zhipeng; Jiang, Lelun; Yuan, Wei; Liang, Liang

    2017-01-01

    Microneedle arrays (MA) have been extensively investigated in recent decades for transdermal drug delivery due to their pain-free delivery, minimal skin trauma, and reduced risk of infection. However, porous MA received relatively less attention due to their complex fabrication process and ease of fracturing. Here, we present a titanium porous microneedle array (TPMA) fabricated by modified metal injection molding (MIM) technology. The sintering process is simple and suitable for mass production. TPMA was sintered at a sintering temperature of 1250°C for 2 h. The porosity of TPMA was approximately 30.1% and its average pore diameter was about 1.3 μm. The elements distributed on the surface of TPMA were only Ti and O, which may guarantee the biocompatibility of TPMA. TPMA could easily penetrate the skin of a human forearm without fracture. TPMA could diffuse dry Rhodamine B stored in micropores into rabbit skin. The cumulative permeated flux of calcein across TPMA with punctured skin was 27 times greater than that across intact skin. Thus, TPMA can continually and efficiently deliver a liquid drug through open micropores in skin. PMID:28187179

  2. Influence of the power law index on the fiber breakage during injection molding by numerical simulations

    NASA Astrophysics Data System (ADS)

    Desplentere, Frederik; Six, Wim; Bonte, Hilde; Debrabandere, Eric

    2013-04-01

    In predictive engineering for polymer processes, the proper prediction of material microstructure from known processing conditions and constituent material properties is a critical step forward properly predicting bulk properties in the finished composite. Operating within the context of long-fiber thermoplastics (LFT, length > 15mm) this investigation concentrates on the influence of the power law index on the final fiber length distribution within the injection molded part. To realize this, the Autodesk Simulation Moldflow Insight Scandium 2013 software has been used. In this software, a fiber breakage algorithm is available from this release on. Using virtual material data with realistic viscosity levels allows to separate the influence of the power law index on the fiber breakage from the other material and process parameters. Applying standard settings for the fiber breakage parameters results in an obvious influence on the fiber length distribution through the thickness of the part and also as function of position in the part. Finally, the influence of the shear rate constant within the fiber breakage model has been investigated illustrating the possibility to fit the virtual fiber length distribution to the possible experimentally available data.

  3. Sintering Behavior and Microstructure Formation of Titanium Aluminide Alloys Processed by Metal Injection Molding

    NASA Astrophysics Data System (ADS)

    Soyama, Juliano; Oehring, Michael; Ebel, Thomas; Kainer, Karl Ulrich; Pyczak, Florian

    2017-01-01

    The sintering behavior of metal injection molded titanium aluminide alloys, their microstructure formation and resulting mechanical properties were investigated. As reference material, the alloy Ti-45Al-5Nb-0.2B-0.2C at.% (TNB-V5) was selected. Additionally, two other variations with Mo and Mo + Si additions were prepared: Ti-45Al-3Nb-1Mo-0.2B-0.2C at.% and Ti-45Al-3Nb-1Mo-1Si-0.2B-0.2C at.%. The results indicate that the optimum sintering temperature was slightly above the solidus line. With proper sintering parameters, very low porosities (<0.5%) and fine microstructures with a colony size <85 µm could be achieved. Considering the sintering temperatures applied, the phase transformations upon cooling could be described as L + β → β → α + β → α → α + γ → α2 + γ, which was in agreement with the microstructures observed. The effects of Mo and Si were opposite regarding the sintering behavior. Mo addition led to an increase in the optimum sintering temperature, whereas Si caused a significant decrease.

  4. Injection molded plastic helical gear filled with carbon powder made from rice hull

    NASA Astrophysics Data System (ADS)

    Chen, Yen Chu; Itagaki, Takayoshi; Takahashi, Hideo; Takahashi, Mikio

    2017-07-01

    Natural materials are focused on the ecological responsibility, all over the world. The rice-hull contains natural silica about 20 wt.%. Therefore, a carbonized rice-hull; Rice-Hull-Silica-Carbon (RHSC) is focused as effective utilization of the discarded rice hull. In this study, test plastic helical gears were made form polyacetal copolymer filled with RHSC powder by injection molding. Test helical gears were operated on endurance test. The bulk temperature and noise of test gears were measured during gears operation. Then, the tooth damage of test gears were investigated by using optical microscope. It is clarified that difference of tooth damage by kind of test gears. Moreover, the transition of gear bulk temperature and noise during operation are investigated. Based on these results, the effect of RHSC powder is discussed. From the discussions, it seems reasonable to conclude : (1) The heat resistance of plastic gear is improved by adding the RHSC powder. (2) The fatigue life of plastic gear is improved by adding suitable amount of the RHSC powder. (3) The sound pressure level of plastic gear is reduced by adding the smaller median grain diameter of RHSC powder.

  5. An injection molded microchip for nucleic acid purification from 25 microliter samples using isotachophoresis.

    PubMed

    Marshall, L A; Rogacs, A; Meinhart, C D; Santiago, J G

    2014-02-28

    We present a novel microchip device for purification of nucleic acids from 25μL biological samples using isotachophoresis (ITP). The device design incorporates a custom capillary barrier structure to facilitate robust sample loading. The chip uses a 2mm channel width and 0.15mm depth to reduce processing time, mitigate Joule heating, and achieve high extraction efficiency. To reduce pH changes in the device due to electrolysis, we incorporated a buffering reservoir physically separated from the sample output reservoir. To reduce dispersion of the ITP-focused zone, we used optimized turn geometries. The chip was fabricated by injection molding PMMA and COC plastics through a commercial microfluidic foundry. The extraction efficiency of nucleic acids from the device was measured using fluorescent quantification, and an average recovery efficiency of 81% was achieved for nucleic acid masses between 250pg and 250ng. The devices were also used to purify DNA from whole blood, and the extracted DNA was amplified using qPCR to show the PCR compatibility of the purified sample. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Ceramic micro-injection molded nozzles for serial femtosecond crystallography sample delivery

    SciTech Connect

    Beyerlein, K. R.; Heymann, M.; Kirian, R.; Adriano, L.; Bajt, S.; Knoška, J.; Wilde, F.; Chapman, H. N.

    2015-12-15

    Serial femtosecond crystallography (SFX) using X-ray Free-Electron Lasers (XFELs) allows for room temperature protein structure determination without evidence of conventional radiation damage. In this method, a liquid suspension of protein microcrystals can be delivered to the X-ray beam in vacuum as a micro-jet, which replenishes the crystals at a rate that exceeds the current XFEL pulse repetition rate. Gas dynamic virtual nozzles produce the required micrometer-sized streams by the focusing action of a coaxial sheath gas and have been shown to be effective for SFX experiments. Here, we describe the design and characterization of such nozzles assembled from ceramic micro-injection molded outer gas-focusing capillaries. Trends of the emitted jet diameter and jet length as a function of supplied liquid and gas flow rates are measured by a fast imaging system. The observed trends are explained by derived relationships considering choked gas flow and liquid flow conservation. Finally, the performance of these nozzles in a SFX experiment is presented, including an analysis of the observed background.

  7. Three-dimensional smoothed particle hydrodynamics simulation for injection molding flow of short fiber-reinforced polymer composites

    NASA Astrophysics Data System (ADS)

    He, Liping; Lu, Gang; Chen, Dachuan; Li, Wenjun; Lu, Chunsheng

    2017-07-01

    This paper investigates the three-dimensional (3D) injection molding flow of short fiber-reinforced polymer composites using a smoothed particle hydrodynamics (SPH) simulation method. The polymer melt was modeled as a power law fluid and the fibers were considered as rigid cylindrical bodies. The filling details and fiber orientation in the injection-molding process were studied. The results indicated that the SPH method could effectively predict the order of filling, fiber accumulation, and heterogeneous distribution of fibers. The SPH simulation also showed that fibers were mainly aligned to the flow direction in the skin layer and inclined to the flow direction in the core layer. Additionally, the fiber-orientation state in the simulation was quantitatively analyzed and found to be consistent with the results calculated by conventional tensor methods.

  8. Acoustic Emission Detection of Macro-Cracks on Engraving Tool Steel Inserts during the Injection Molding Cycle Using PZT Sensors

    PubMed Central

    Svečko, Rajko; Kusić, Dragan; Kek, Tomaž; Sarjaš, Andrej; Hančič, Aleš; Grum, Janez

    2013-01-01

    This paper presents an improved monitoring system for the failure detection of engraving tool steel inserts during the injection molding cycle. This system uses acoustic emission PZT sensors mounted through acoustic waveguides on the engraving insert. We were thus able to clearly distinguish the defect through measured AE signals. Two engraving tool steel inserts were tested during the production of standard test specimens, each under the same processing conditions. By closely comparing the captured AE signals on both engraving inserts during the filling and packing stages, we were able to detect the presence of macro-cracks on one engraving insert. Gabor wavelet analysis was used for closer examination of the captured AE signals' peak amplitudes during the filling and packing stages. The obtained results revealed that such a system could be used successfully as an improved tool for monitoring the integrity of an injection molding process. PMID:23673677

  9. Injection molding as a one-step process for the direct production of pharmaceutical dosage forms from primary powders.

    PubMed

    Eggenreich, K; Windhab, S; Schrank, S; Treffer, D; Juster, H; Steinbichler, G; Laske, S; Koscher, G; Roblegg, E; Khinast, J G

    2016-05-30

    The objective of the present study was to develop a one-step process for the production of tablets directly from primary powder by means of injection molding (IM), to create solid-dispersion based tablets. Fenofibrate was used as the model API, a polyvinyl caprolactame-polyvinyl acetate-polyethylene glycol graft co-polymer served as a matrix system. Formulations were injection-molded into tablets using state-of-the-art IM equipment. The resulting tablets were physico-chemically characterized and the drug release kinetics and mechanism were determined. Comparison tablets were produced, either directly from powder or from pre-processed pellets prepared via hot melt extrusion (HME). The content of the model drug in the formulations was 10% (w/w), 20% (w/w) and 30% (w/w), respectively. After 120min, both powder-based and pellet-based injection-molded tablets exhibited a drug release of 60% independent of the processing route. Content uniformity analysis demonstrated that the model drug was homogeneously distributed. Moreover, analysis of single dose uniformity also revealed geometric drug homogeneity between tablets of one shot. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. The effect of aging treatment on the fracture toughness and impact strength of injection molded Ni-625 superalloy parts

    SciTech Connect

    Özgün, Özgür; Yılmaz, Ramazan; Özkan Gülsoy, H.; Fındık, Fehim

    2015-10-15

    In this study, the effect of aging heat treatment on fracture toughness and impact strength of Ni-625 superalloy fabricated by using powder injection molding (PIM) method was examined. After a feedstock was prepared by mixing the prealloyed Ni-625 superalloy powder, which was fabricated by gas atomisation, with a polymeric binder system and then it was granulated, it was shaped through the use of injection. The molded specimens were sintered at 1300 °C for 3 h after a two-stage debinding process. Once the sintered specimens were treated in the solution at 1150 °C for 2 h, they were quenched. Aging treatment was performed by keeping specimens at 745 °C for 22 h. Fracture toughness and impact tests were performed on sintered and aged specimens. Microstructure examinations were performed by using optical microscope, scanning electron microscope, and transmission electron microscope. The results revealed that aging heat treatment led to the formation of some carbides and intermetallic phases in the microstructure. While the hardness of the aged specimens increased due to these phases, their fracture toughness and impact strength values decreased. - Highlights: • Ni-625 superalloy components were produced by means of powder injection molding. • The produced components were subjected to aging treatment. • Aging process provided approximately 50% increase in the hardness of components. • Intermetallic precipitates, carbides and TCP phases occurred within the aged parts. • Fracture toughness and impact strength values decreased due to the hard phases.

  11. Fabrication of Bonding-Type Hollow Microneedle Array by Injection Molding and Evaluation of its Puncture Characteristics

    NASA Astrophysics Data System (ADS)

    Ogai, Noriyuki; Sugimura, Ryo; Tamaru, Takuya; Takiguchi, Yoshihiro

    A microneedle array which consists from small needles compared to a conventional metal injection needle is expected as a low invasive transdermal medical treatment device, and many fabrication approach have been conducted. In this study, we fabricated plastic hollow microneedle array by a fabrication method based on the combination of injection molding, bonding and assembly techniques. To evaluate puncture characteristics of the fabricated needle, we measured a puncture force to silicone rubber by experimental equipment using loadcell and automatic stage. Furthermore, we propose and demonstrate a new method to measure actual punctured depth from punctured trace on the needle surface modified by O2 plasma treatment.

  12. In-line polariscopic checking of plastic molded-injected lenses: preliminary results

    NASA Astrophysics Data System (ADS)

    Arasa, J.; Mayershofer, D.; Romero, J.

    2015-05-01

    Plastic injection molded lenses have improved its performance and, nowadays, are as usual as glass lenses in image forming devices. However, the manufacturing process induces the surface generation and the material transformation in the same stage. Moreover, the process also includes an annealing stage to remove the internal stress with temperature cycles but only works up to a certain level and not beyond, leaving relevant traces for high values. During the manufacturing process of a plastic lens, a liquid-solid phase transformation occurs, and in this transition not all the volume of the lens achieves the same density. This change of density is translated into a local change of refractive index that can be expressed as a retardation phase plane using the Jones Matrix notation. The detection and measurement of the value of the retardation of the phase plane is thus the clue to manufacture good and controlled quality plastic lenses. We have tested an in-line polariscopic arrangement to obtain a 2D map of the tension distribution in the bulk of the lens. This test is performed in the first 30 seconds after the injection molding process for two main reasons: first the stress values are still high because the lenses do not have enough time to relax the internal tensions and obtain the final shape, and second, we can remove the wrong lenses in the first moments and introduce only the good lenses in the annealing stage. The proposed instrument is based in a transmission polariscopic arrangement. A collimated light beam is used to illuminate the sample, once the light crosses the sample, it is collected with an afocal system and the image is recorded in a CMOS sensor. Selecting an afocal system to capture the image is a useful decision because the lateral magnification can be maintained when small changes in the sample position are introduced. However the produced lenses can vary their focal lengths from on series to another. To avoid problems with the change of the

  13. Predictive Engineering Tools for Injection-molded Long-Carbon-Fiber Thermoplastic Composites - FY 2014 Third Quarterly Report

    SciTech Connect

    Nguyen, Ba Nghiep; Sanborn, Scott E.; Mathur, Raj N.; Sharma, Bhisham; Sangid, Michael D.; Wang, Jin; Jin, Xiaoshi; Costa, Franco; Gandhi, Umesh N.; Mori, Steven; Tucker III, Charles L.

    2014-08-15

    This report describes the technical progresses made during the third quarter of FY 2014: 1) Autodesk introduced the options for fiber inlet condition to the 3D solver. These options are already available in the mid-plane/dual domain solver. 2) Autodesk improved the accuracy of 3D fiber orientation calculation around the gate. 3) Autodesk received consultant services from Prof. C.L. Tucker at the University of Illinois on the implementation of the reduced order model for fiber length, and discussed with Prof. Tucker the methods to reduce memory usage. 4) PlastiComp delivered to PNNL center-gated and edge-fan-gated 20-wt% to 30-wt% LCF/PP and LCF/PA66 (7”x7”x1/8”) plaques molded by the in-line direct injection molding (D-LFT) process. 5) PlastiComp molded ASTM tensile, flexural and impact bars under the same D-LFT processing conditions used for plaques for Certification of Assessment and ascertaining the resultant mechanical properties. 6) Purdue developed a new polishing routine, utilizing the automated polishing machine, to reduce fiber damage during surface preparation. 7) Purdue used a marker-based watershed segmentation routine, in conjunction with a hysteresis thresholding technique, for fiber segmentation during fiber orientation measurement. 8) Purdue validated Purdue’s fiber orientation measurement method using the previous fiber orientation data obtained from the Leeds machine and manually measured data by the University of Illinois. 9) PNNL conducted ASMI mid-plane analyses for a 30wt% LCF/PP plaque and compared the predicted fiber orientations with the measured data provided by Purdue University at the selected locations on this plaque. 10) PNNL put together the DOE 2014 Annual Merit Review (AMR) presentation with the team and presented it at the AMR meetings on June 17, 2014. 11) PNNL built ASMI dual domain models for the Toyota complex part and commenced mold filling analyses of the complex part with different wall thicknesses in order to

  14. Tribological and mechanical performance evaluation of metal prosthesis components manufactured via metal injection molding.

    PubMed

    Melli, Virginia; Juszczyk, Mateusz; Sandrini, Enrico; Bolelli, Giovanni; Bonferroni, Benedetta; Lusvarghi, Luca; Cigada, Alberto; Manfredini, Tiziano; De Nardo, Luigi

    2015-01-01

    The increasing number of total joint replacements, in particular for the knee joint, has a growing impact on the healthcare system costs. New cost-saving manufacturing technologies are being explored nowadays. Metal injection molding (MIM) has already demonstrated its suitability for the production of CoCrMo alloy tibial trays, with a significant reduction in production costs, by holding both corrosion resistance and biocompatibility. In this work, mechanical and tribological properties were evaluated on tibial trays obtained via MIM and conventional investment casting. Surface hardness and wear properties were evaluated through Vickers hardness, scratch and pin on disk tests. The MIM and cast finished tibial trays were then subjected to a fatigue test campaign in order to obtain their fatigue load limit at 5 millions cycles following ISO 14879-1 directions. CoCrMo cast alloy exhibited 514 HV hardness compared to 335 HV of MIM alloy, furthermore it developed narrower scratches with a higher tendency towards microploughing than microcutting, in comparison to MIM CoCrMo. The observed fatigue limits were (1,766 ± 52) N for cast tibial trays and (1,625 ± 44) N for MIM ones. Fracture morphologies pointed out to a more brittle behavior of MIM microstructure. These aspects were attributed to the absence of a fine toughening and surface hardening carbide dispersion in MIM grains. Nevertheless, MIM tibial trays exhibited a fatigue limit far beyond the 900 N of maximum load prescribed by ISO and ASTM standards for the clinical application of these devices.

  15. Finger-powered microfluidic systems using multilayer soft lithography and injection molding processes.

    PubMed

    Iwai, Kosuke; Shih, Kuan Cheng; Lin, Xiao; Brubaker, Thomas A; Sochol, Ryan D; Lin, Liwei

    2014-10-07

    Point-of-care (POC) and disposable biomedical applications demand low-power microfluidic systems with pumping components that provide controlled pressure sources. Unfortunately, external pumps have hindered the implementation of such microfluidic systems due to limitations associated with portability and power requirements. Here, we propose and demonstrate a 'finger-powered' integrated pumping system as a modular element to provide pressure head for a variety of advanced microfluidic applications, including finger-powered on-chip microdroplet generation. By utilizing a human finger for the actuation force, electrical power sources that are typically needed to generate pressure head were obviated. Passive fluidic diodes were designed and implemented to enable distinct fluids from multiple inlet ports to be pumped using a single actuation source. Both multilayer soft lithography and injection molding processes were investigated for device fabrication and performance. Experimental results revealed that the pressure head generated from a human finger could be tuned based on the geometric characteristics of the pumping system, with a maximum observed pressure of 7.6 ± 0.1 kPa. In addition to the delivery of multiple, distinct fluids into microfluidic channels, we also employed the finger-powered pumping system to achieve the rapid formation of both water-in-oil droplets (106.9 ± 4.3 μm in diameter) and oil-in-water droplets (75.3 ± 12.6 μm in diameter) as well as the encapsulation of endothelial cells in droplets without using any external or electrical controllers.

  16. Evaluation of Micro-drilling Technologies for Metal Injection Molded 420 Stainless Steel

    NASA Astrophysics Data System (ADS)

    Silverman, David Elion

    Metal injection molded (MIM) 420 stainless steel is a commonly used material for high-value products such as fuel injector nozzles. However, the trade-offs involved in using different micro-drilling processes on this material are not well-documented in literature. This thesis presents a micro-drilling study of MIM 420 stainless steel using four candidate processes, viz., micro-electrical discharge drilling (micro-EDD), ultrasonically-assisted micro-EDD, micro-mechanical drilling (micro-MD) and ultrasonically-assisted micro-MD. The micro-EDD results shows that the use of ultrasonic vibrations significantly improves the overall process time, spark erosion efficiency and material removal rate of the process. However, this improvement comes at the expense of increased tool wear and surface roughness, especially while machining under high discharge energy conditions. The micro-MD results show that the use of ultrasonic vibrations is beneficial in lowering the thrust force, drilling torque and tool-wear at chipload values greater than the minimum chip thickness of the material. However, the ultrasonic vibrations do not have a notable effect on the surface roughness or on the size of the exit burrs. The results obtained from this study have been used to develop a Likert-type comparison scale to enable application-specific selection of micro-drilling processes for MIM 420 stainless steel. Finally, the benefits of using the ultrasonically-assisted micro-EDD process seen during the laboratory tests at Rensselaer were observed to carry over to the production environment of our NYSERDA funded industrial sponsor.

  17. Low Speed Technology for Small Turbine Development Reaction Injection Molded 7.5 Meter Wind Turbine Blade

    SciTech Connect

    David M. Wright; DOE Project Officer - Keith Bennett

    2007-07-31

    An optimized small turbine blade (7.5m radius) was designed and a partial section molded with the RIM (reaction-injection molded polymer) process for mass production. The intended market is for generic three-bladed wind turbines, 100 kilowatts or less, for grid-assist end users with rural and semi-rural sites, such as the farm/ranch market, having low to moderate IEC Class 3-4 wind regimes. This blade will have substantial performance improvements over, and be cheaper than, present-day 7.5m blades. This is made possible by the injection-molding process, which yields high repeatability, accurate geometry and weights, and low cost in production quantities. No wind turbine blade in the 7.5m or greater size has used this process. The blade design chosen uses a RIM skin bonded to a braided infused carbon fiber/epoxy spar. This approach is attractive to present users of wind turbine blades in the 5-10m sizes. These include rebladeing California wind farms, refurbishing used turbines for the Midwest farm market, and other manufacturers introducing new turbines in this size range.

  18. Effects of size reduction on deformation, microstructure, and surface roughness of micro components for micro metal injection molding

    NASA Astrophysics Data System (ADS)

    Liu, Lin; Wang, Xin-da; Li, Xiang; Qi, Xiao-tong; Qu, Xuan-hui

    2017-09-01

    The fabrication of 17-4PH micro spool mandrils by micro metal injection molding was described here. The effects of size reduction on deformation, microstructure and surface roughness were studied by comparing a ϕ500 μm micro post and a ϕ1.7 mm cylinder after debinding and sintering. Experimental results show that slumping of the micro posts occurred due to a dramatic increase in outlet vapor pressure initiated at the thermal degradation onset temperature and the moment of gravity. Asymmetrical stress distribution within the micro component formed during the cooling stage may cause warping. Prior solvent debinding and adjustment in a thermal debinding scheme were useful for preventing the deformation of the micro components. Smaller grain size and higher micro hardness due to impeded grain growth were observed for the micro posts compared with the ϕ1.7 mm cylinder. Surface roughness increased with distance from the gate of the micro spool mandril due to melt front advancement during mold filling and the ensuing pressure distribution. At each position, surface roughness was dictated by injection molding and increased slightly after sintering.

  19. A novel injection-molded capsular device for oral pulsatile delivery based on swellable/erodible polymers.

    PubMed

    Gazzaniga, Andrea; Cerea, Matteo; Cozzi, Alberto; Foppoli, Anastasia; Maroni, Alessandra; Zema, Lucia

    2011-03-01

    The feasibility of injection molding was explored in the preparation of a novel capsular device for oral pulsatile/delayed delivery based on swellable/erodible polymers. For this purpose, a mold intended to be coupled with a bench-top injection-molding press was designed. This was expected to enable the preparation of matching capsule cap and body items within a single manufacturing cycle and the selection of differing shell thicknesses (300, 600, and 900 μm). Hydroxypropylcellulose (Klucel(®) EF, LF, and GF) was employed as the release-controlling polymer in admixture with polyethylene glycol 1500 (10%, w/w) as the plasticizer. After preliminary trials aimed at the setup of operating conditions, Klucel(®) EF and LF capsule shells with satisfactory technological properties were manufactured. The performance of capsular devices filled with a tracer drug powder was studied by means of a modified USP31 disintegration apparatus. Typical in vitro delayed release patterns were thereby obtained, with lag time increasing as a function of the wall thickness. A good correlation was found between the latter parameter and t (10%), i.e., the time to 10% release, for both polymer grades employed. On the basis of the overall results, the investigated technique was proven suitable for the manufacturing of an innovative pulsatile release platform.

  20. Production of Insulated Footwear Using Liquid Injection Molding Equipment. 2. Instruction Manual

    DTIC Science & Technology

    1980-09-01

    VERMICULITE and PERLITE have been found to be satisfactory. Personal dealing with the clean-up of spills should wear a gas mask (organic vapor canister) or use...contained breathing apparatus. If spillage occurs, immediately cover the spill with an excess of VERMICULITE or PERLITE only. Using breathing protection...Tack Free Time: time from discharge 84 from mixer until foam surface is not tacky to light touch). 7. Set up boot molding station. (a) Bolt in mold

  1. Simulation of the Cooling of a Semi-Crystalline Polymer in the Injection Molding Process Including PVT Behavior

    NASA Astrophysics Data System (ADS)

    Brahmia, Nadia; Zinet, Matthieu; Boutaous, M'hamed; Chantrenne, Patrice; Bourgin, Patrick; Garcia, David

    2007-05-01

    Accurate numerical simulation of the injection molding process requires a good comprehension of the cooling and solidification phase. In the case of semi-crystalline polymers, this task is complicated because of a strong coupling between heat transfer, crystallization and material compressibility effects. In this work, we carry out the thermophysical characterization of a semi-crystalline polymer (isotactic polypropylene), including the pressure-volume-temperature (PVT) behavior. Then we present a model of the isochoric cooling of this polymer, taking into account these couplings. This model enables us to compute the evolution of pressure, temperature, relative crystallinity and local specific volume in the mold cavity from high initial pressure down to atmospheric pressure and shrinkage onset.

  2. Comparison of peri-implant bone formation around injection-molded and machined surface zirconia implants in rabbit tibiae.

    PubMed

    Kim, Hong-Kyun; Woo, Kyung Mi; Shon, Won-Jun; Ahn, Jin-Soo; Cha, Seunghee; Park, Young-Seok

    2015-01-01

    The aim of this study was to compare osseointegration and surface characteristics of zirconia implants made by the powder injection molding (PIM) technique against those made by the conventional milling procedure in rabbit tibiae. Surface characteristics of 2 types of implants were evaluated. Sixteen rabbits received 2 types of external hex implants with similar geometry, either machined zirconia implants or PIM zirconia implants, in the tibiae. Removal torque tests and histomorphometric analyses were performed. The roughness of the PIM zirconia implants was higher than that of machined zirconia implants. The PIM zirconia implants exhibited significantly higher bone-implant contact and removal torque values than the machined zirconia implants (p<0.001). The osseointegration of the PIM zirconia implant is promising, and PIM, using the roughened mold etching technique, can produce substantially rougher surfaces on zirconia implants.

  3. Predictive Engineering Tools for Injection-Molded Long-Carbon-Fiber Thermoplastic Composites - Fourth FY 2015 Quarterly Report

    SciTech Connect

    Nguyen, Ba Nghiep; Fifield, Leonard S.; Wollan, Eric J.; Roland, Dale; Gandhi, Umesh N.; Mori, Steven; Lambert, Gregory; Baird, Donald G.; Wang, Jin; Costa, Franco; Tucker III, Charles L.

    2015-11-13

    During the last quarter of FY 2015, the following technical progress has been made toward project milestones: 1) PlastiComp used the PlastiComp direct in-line (D-LFT) Pushtrusion system to injection mold 40 30wt% LCF/PP parts with ribs, 40 30wt% LCF/PP parts without ribs, 10 30wt% LCF/PA66 parts with ribs, and 35 30wt% LCF/PA66 parts without ribs. In addition, purge materials from the injection molding nozzle were obtained for fiber length analysis, and molding parameters were sent to PNNL for process modeling. 2) Magna cut samples at four selected locations (named A, B, C and D) from the non-ribbed Magna-molded parts based on a plan discussed with PNNL and the team and shipped these samples to Virginia Tech for fiber orientation and length measurements. 3) Virginia Tech started fiber orientation and length measurements for the samples taken from the complex parts using Virginia Tech’s established procedure. 4) PNNL and Autodesk built ASMI models for the complex parts with and without ribs, reviewed process datasheets and performed preliminary analyses of these complex parts using the actual molding parameters received from Magna and PlastiComp to compare predicted to experimental mold filling patterns. 5) Autodesk assisted PNNL in developing the workflow to use Moldflow fiber orientation and length results in ABAQUS® simulations. 6) Autodesk advised the team on the practicality and difficulty of material viscosity characterization from the D-LFT process. 7) PNNL developed a procedure to import fiber orientation and length results from a 3D ASMI analysis to a 3D ABAQUS® model for structural analyses of the complex part for later weight reduction study. 8) In discussion with PNNL and Magna, Toyota developed mechanical test setups and built fixtures for three-point bending and torsion tests of the complex parts. 9) Toyota built a finite element model for the complex parts subjected to torsion loading. 10) PNNL built the 3D ABAQUS® model of the complex ribbed

  4. Predictive engineering tools for injection-molded long-carbon-fiber thermoplastic composites - FY 2015 third quarterly report

    SciTech Connect

    Nguyen, Ba Nghiep; Fifield, Leonard S.; Mori, Steven; Gandhi, Umesh N.; Wang, Jin; Costa, Franco; Wollan, Eric J.; Tucker, III, Charles L.

    2015-07-01

    During the third quarter of FY 2015, the following technical progress has been made toward project milestones: 1) Magna oversaw the tool build and prepared the molding plan for the complex part of Phase II. 2) PlastiComp hosted a visit by Magna and Toyota on April 23rd to finalize the molding scope and schedule. The plan for molding trials including selection of molding parameters for both LFT and D-LFT for the U-shape complex part was established. 3) Toyota shipped the U-shape complex part tool to Magna on May 28th, 2015. 4) Plasticomp provided 30wt% LCF/PP and 30wt% LCF/PA66 compounded pellets to Magna for molding the complex part. 5) Magna performed preliminary molding trials on June 2nd, 2015 to validate wall thickness, fill profile, tool temperature and shot size requirements for the complex part. 6) Magna performed the first complex part run on June 16th and 17th, 2015 at Magna’s Composite Centre of Excellence in Concord, ON, Canada. Dale Roland of Plasticomp, and Umesh Gandhi of Toyota also attended the molding. 7) Magna discussed and finalized the plan with PNNL and the team for cutting samples from molded parts at selected locations for fiber orientation and length measurements. 8) Magna provided the computer-aided design (CAD) files of the complex parts with and without ribs to PNNL and Autodesk to build the corresponding ASMI models for injection molding simulations. Magna also provided the actual parameters used. 9) Plasticomp’s provided knowledge and experience of molding LCF materials essential to the successful molding of the parts including optimization of fill speed, tool temperatures, and plasticizing conditions for the 30wt% LCF/PP and 30wt% LCF/PA66 materials in both rib and non-rib versions. 10) Magna molded additional parts for evaluation of mechanical property testing including torsional stiffness on June 29th and 30th, 2015 at Magna’s Composite Center of Excellence. 11) Toyota began preparation for the torsion test of the specimens

  5. Spray-formed tooling for injection molding and die casting applications

    SciTech Connect

    K. M. McHugh; B. R. Wickham

    2000-06-26

    Rapid Solidification Process (RSP) Tooling{trademark} is a spray forming technology tailored for producing molds and dies. The approach combines rapid solidification processing and net-shape materials processing in a single step. The ability of the sprayed deposit to capture features of the tool pattern eliminates costly machining operations in conventional mold making and reduces turnaround time. Moreover, rapid solidification suppresses carbide precipitation and growth, allowing many ferritic tool steels to be artificially aged, an alternative to conventional heat treatment that offers unique benefits. Material properties and microstructure transformation during heat treatment of spray-formed H13 tool steel are described.

  6. Spray-formed Tooling for Injection Molding and Die Casting Applications

    SciTech Connect

    Mc Hugh, Kevin Matthew

    2000-06-01

    Rapid Solidification Process (RSP) ToolingTM is a spray forming technology tailored for producing molds and dies. The approach combines rapid solidification processing and net-shape materials processing in a single step. The ability of the sprayed deposit to capture features of the tool pattern eliminates costly machining operations in conventional mold making and reduces turnaround time. Moreover, rapid solidification suppresses carbide precipitation and growth, allowing many ferritic tool steels to be artificially aged, an alternative to conventional heat treatment that offers unique benefits. Material properties and microstructure transformation during heat treatment of spray-formed H13 tool steel are described.

  7. Portable CE system with contactless conductivity detection in an injection molded polymer chip for on-site food analysis

    NASA Astrophysics Data System (ADS)

    Becker, Holger; Mühlberger, Holger; Hoffmann, Werner; Clemens, Thomas; Klemm, Richard; Gärtner, Claudia

    2008-02-01

    We present a compact portable chip-based capillary electrophoresis system that employs capacitively coupled contactless conductivity detection (C 4D) operating at 4 MHz as an alternative detection method compared to the commonly used optical detection employing laser-induced fluorescence. The disposable chip for this system is fabricated out of PMMA using injection molding; the electrodes are screen-printed or thin-film electrodes. The system allows the measurement of small ions like Li, Na, K typically present in foodstuff like milk and mineral water as well as acids in wine.

  8. Microengineering of Metals and Ceramics: Part I: Design, Tooling and Injection Molding; Volume 3: Advanced Micro & Nanosystems

    NASA Astrophysics Data System (ADS)

    Baltes, Henry; Brand, Oliver; Fedder, Gary K.; Hierold, Christofer; Korvink, Jan G.; Tabata, Osamu; Löhe, Detlef; Haußelt, Jürgen

    2005-09-01

    Microstructures, electronics, nanotechnology - these vast fields of research are growing together as the size gap narrows and many different materials are combined. Current research, engineering sucesses and newly commercialized products hint at the immense innovative potentials and future applications that open up once mankind controls shape and function from the atomic level right up to the visible world without any gaps. In this volume, authors from three major competence centres for microengineering illustrate step by step the process from designing and simulating microcomponents of metallic and ceramic materials to replicating micro-scale components by injection molding.

  9. Application of Rapid Prototyping and Wire Arc Spray to the Fabrication of Injection Mold Tools (MSFC Center Director's Discretionary Fund)

    NASA Technical Reports Server (NTRS)

    Cooper, K. G.

    2000-01-01

    Rapid prototyping (RP) is a layer-by-layer-based additive manufacturing process for constructing three-dimensional representations of a computer design from a wax, plastic, or similar material. Wire arc spray (WAS) is a metal spray forming technique, which deposits thin layers of metal onto a substrate or pattern. Marshall Space Flight Center currently has both capabilities in-house, and this project proposed merging the two processes into an innovative manufacturing technique, in which intermediate injection molding tool halves were to be fabricated with RP and WAS metal forming.

  10. Evaluation of hot-melt extrusion and injection molding for continuous manufacturing of immediate-release tablets.

    PubMed

    Melocchi, Alice; Loreti, Giulia; Del Curto, Maria Dorly; Maroni, Alessandra; Gazzaniga, Andrea; Zema, Lucia

    2015-06-01

    The exploitation of hot-melt extrusion and injection molding for the manufacturing of immediate-release (IR) tablets was preliminarily investigated in view of their special suitability for continuous manufacturing, which represents a current goal of pharmaceutical production because of its possible advantages in terms of improved sustainability. Tablet-forming agents were initially screened based on processability by single-screw extruder and micromolding machine as well as disintegration/dissolution behavior of extruded/molded prototypes. Various polymers, such as low-viscosity hydroxypropylcellulose, polyvinyl alcohol, polyvinyl alcohol-polyethylene glycol graft copolymer, various sodium starch glycolate grades (e.g., Explotab(®) CLV) that could be processed with no need for technological aids, except for a plasticizer, were identified. Furthermore, the feasibility of both extruded and molded IR tablets from low-viscosity hydroxypropylcellulose or Explotab(®) CLV was assessed. Explotab(®) CLV, in particular, showed thermoplastic properties and a very good aptitude as a tablet-forming agent, starting from which disintegrating tablets were successfully obtained by either techniques. Prototypes containing a poorly soluble model drug (furosemide), based on both a simple formulation (Explotab(®) CLV and water/glycerol as plasticizers) and formulations including dissolution/disintegration adjuvants (soluble and effervescent excipients) were shown to fulfill the USP 37 dissolution requirements for furosemide tablets.

  11. 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.

  12. Numerical simulation of fiber interaction in short-fiber injection-molded composite using different cavity geometries

    SciTech Connect

    Thi, Thanh Binh Nguyen Yokoyama, Atsushi; Hamanaka, Senji; Yamashita, Katsuhisa; Nonomura, Chisato

    2016-03-09

    The theoretical fiber-interaction model for calculating the fiber orientation in the injection molded short fiber/thermoplastic composite parts was proposed. The proposed model included the fiber dynamics simulation in order to obtain an equation of the global interaction coefficient and accurate estimate of the fiber interacts at all orientation states. The steps to derive the equation for this coefficient in short fiber suspension as a function of the fiber aspect ratio, volume fraction and general shear rate are delineated. Simultaneously, the high-resolution 3D X-ray computed tomography system XVA-160α was used to observe fiber distribution of short-glass-fiber-reinforced polyamide specimens using different cavity geometries. The fiber orientation tensor components are then calculated. Experimental orientation measurements of short-glass-fiber-reinforced polyamide is used to check the ability of present theory for predicting orientation. The experiments and predictions show a quantitative agreement and confirm the basic understanding of fiber orientation in injection-molded composites.

  13. Effect of fiber content on flexural properties of glass fiber-reinforced polyamide-6 prepared by injection molding.

    PubMed

    Nagakura, Manamu; Tanimoto, Yasuhiro; Nishiyama, Norihiro

    2017-02-11

    The use of non-metal clasp denture (NMCD) materials may seriously affect the remaining tissues because of the low rigidity of NMCD materials such as polyamides. The purpose of this study was to develop a high-rigidity glass fiber-reinforced thermoplastic (GFRTP) composed of E-glass fiber and polyamide-6 for NMCDs using an injection molding. The reinforcing effects of fiber on the flexural properties of GFRTPs were investigated using glass fiber content ranging from 0 to 50 mass%. Three-point bending tests indicated that the flexural strength and elastic modulus of a GFRTP with a fiber content of 50 mass% were 5.4 and 4.7 times higher than those of unreinforced polyamide-6, respectively. The result showed that the physical characteristics of GFRTPs were greatly improved by increasing the fiber content, and the beneficial effects of fiber reinforcement were evident. The findings suggest that the injection-molded GFRTPs are adaptable to NMCDs because of their excellent mechanical properties.

  14. Prediction of the Elastic-Plastic Stress/Strain Response for Injection-Molded Long-Fiber Thermoplastics

    SciTech Connect

    Nguyen, Ba Nghiep; Bapanapalli, Satish K.; Kunc, Vlastimil; Phelps, Jay; Tucker III, Charles L.

    2009-01-26

    This paper proposes a model to predict the elastic-plastic response of injection-molded long-fiber thermoplastics (LFTs). The model accounts for elastic fibers embedded in a thermoplastic resin that exhibits the elastic-plastic behavior obeying the Ramberg-Osgood relation and J-2 deformation theory of plasticity. It also accounts for fiber length and orientation distributions in the composite formed by the injection-molding process. Fiber orientation was predicted using the anisotropic rotary diffusion model recently developed by Phelps and Tucker for LFTs. An incremental procedure using the Eshelby’s equivalent inclusion method and the Mori-Tanaka model is proposed to compute the overall stress increment resulting from an overall strain increment for an aligned fiber composite that contains the same fiber volume fraction and length distribution as the actual composite. The incremental response of the later is then obtained from the solution for the aligned fiber composite that is averaged over all possible fiber orientations using the orientation averaging method. Failure during incremental loading is predicted using the Van Hattum-Bernado model. The elastic-plastic and strength prediction model for LFTs was validated against the experimental stress-strain results obtained for long glass fiber/polypropylene specimens.

  15. Comparison of mechanical properties for polyamide 12 composite-based biomaterials fabricated by fused filament fabrication and injection molding

    NASA Astrophysics Data System (ADS)

    Rahim, Tuan Noraihan Azila Tuan; Abdullah, Abdul Manaf; Akil, Hazizan Md; Mohamad, Dasmawati

    2016-12-01

    The emergence of 3D printing technology known as fused filament fabrication (FFF) has offered the possibility of producing an anatomically accurate, patient specific implant with more affordable prices. The only weakness of this technology is related to incompatibility and lack of properties of current material to be applied in biomedical. Therefore, this study aims to develop a new, polymer composite-based biomaterial that exhibits a high processability using FFF technique, strong enough and shows acceptable biocompatibility, and safe for biomedical use. Polyamide 12 (PA12), which meets all these requirements was incorporated with two bioceramic fillers, zirconia and hydroxyapatite in order to improve the mechanical and bioactivity properties. The obtained mechanical properties were compared with injection-molded specimens and also a commercial biomedical product, HAPEXTM which is composed of hydroxyapatite and polyethylene. The yield strength and modulus of the PA12 composites increased steadily with increasing filler loading. Although the strength of printed PA12 composites were reduced compared with injection molded specimen, but still higher than HAPEXTM material. The higher surface roughness obtained by printed PA12 was expected to enhance the cell adhesion and provide better implant fixation.

  16. Fiber Length and Orientation in Long-Fiber Injection-Molded Thermoplastics. Part I: Modeling of Microstructure and Elastic Properties

    SciTech Connect

    Nguyen, Ba Nghiep; Bapanapalli, Satish K.; Holbery, James D.; Smith, Mark T.; Kunc, Vlastimil; Frame, Barbara J.; Phelps, Jay; Tucker III, Charles L.

    2008-05-01

    This paper investigates the effects of fiber length and orientation distributions on the elastic properties of long-fiber injection-molded thermoplastics (LFTs). The corrected experimental fiber length distribution and the predicted and experimental orientation distributions were used in modeling to compute the elastic properties of the composite. First, from the fiber length distribution (FLD) data in terms of number of fibers versus fiber length, the probability density functions were built and used in the computation. Also, it has been shown that the two-parameter Weibull’s distribution can be used to represent the actual FLD. Next, the Mori-Tanaka model that employs the Eshelby’s equivalent inclusion method was applied to calculate the stiffness matrix of the aligned fiber composite containing the established FLD. The stiffness of the actual as-formed composite was then determined from the stiffness of the computed aligned fiber composite that was averaged over all possible orientations using the orientation averaging method. The methodology to predict the elastic properties of LFTs was validated via experimental verification of the longitudinal and transverse moduli determined for long glass fiber injection-molded polypropylene specimens. Finally, a sensitivity analysis was conducted to determine the effect of a variation of FLD on the composite elastic properties.

  17. Prediction of the Elastic-Plastic Stress/Strain Response for Injection-Molded Long-Fiber Thermoplastics

    SciTech Connect

    Nguyen, Ba N.; Kunc, Vlastimil; Phelps, Jay H; TuckerIII, Charles L.; Bapanapalli, Satish K

    2009-01-01

    This paper proposes a model to predict the elastic-plastic response of injection-molded long-fiber thermoplastics (LFTs). The model accounts for elastic fibers embedded in a thermoplastic resin that exhibits the elastic-plastic behavior obeying the Ramberg-Osgood relation and J-2 deformation theory of plasticity. It also accounts for fiber length and orientation distributions in the composite formed by the injection-molding process. Fiber orientation was predicted using an anisotropic rotary diffusion model recently developed for LFTs. An incremental procedure using Eshelby's equivalent inclusion method and the Mori-Tanaka assumption is proposed to compute the overall stress increment resulting from an overall strain increment for an aligned-fiber composite that contains the same fiber volume fraction and length distribution as the actual composite. The incremental response of the latter is then obtained from the solution for the aligned-fiber composite by averaging over all fiber orientations. Failure during incremental loading is predicted using the Van Hattum-Bernado model. The model is validated against the experimental stress-strain results obtained for long-glass-fiber/polypropylene specimens.

  18. Powder Injection Molding (PIM) for Low Cost Manufacturing of Intricate Parts to Net-Shape

    DTIC Science & Technology

    2006-05-01

    Molding (PIM) for Low Cost Manufacturing of Intricate Parts to Net-Shape 7 - 6 RTO-MP-AVT-139 high temperature materials find applications in...offers significant cost savings, increased design and materials flexibility, increased possibility of miniaturization, high mechanical properties, good...surface finish and high speed production. The activities and expertise in powder metallurgy as well as in process numerical modeling related to

  19. Predictive Engineering Tools for Injection-Molded Long-Carbon-Fiber Thermoplastic Composites - FY 2014 Fourth Quarterly Report

    SciTech Connect

    Nguyen, Ba Nghiep; Fifield, Leonard S.; Mathur, Raj N.; Kijewski, Seth A.; Sangid, Michael D.; Wang, Jin; Jin, Xiaoshi; Costa, Franco; Gandhi, Umesh N.; Mori, Steven; Tucker, III, Charles L.

    2014-09-30

    extract machine purgings (purge materials) from Magna’s 200-Ton Injection Molding machine targeted to mold the complex part. 11) Toyota and Magna discussed with PNNL tool modification for molding the complex part.

  20. Suppressing the Skin-Core Structure of Injection-Molded Isotactic Polypropylene via Combination of an in situ Microfibrillar Network and an Interfacial Compatibilizer

    SciTech Connect

    X Yi; C Chen; G Zhong; L Xu; J Tang; X Ji; B Hsiao; Z Li

    2011-12-31

    Injection-molded semicrystalline polymer parts generally exhibited a so-called skin-core structure basically as a result of the large gradients of temperature, shear rate, stress, and pressure fields created by the boundary conditions of injection molding. Suppression of the skin-core structure is a long-term practical challenge. In the current work, the skin-core structure of the conventional injection-molded isotactic polypropylene (iPP) was largely relieved by the cooperative effects of an in situ microfibrillar network and interfacial compatibilizer. The in situ poly(ethylene terephthalate) microfibrils of 1-8 {micro}m in diameter and large aspect ratios of above 40 tended to entangle with each other to generate a microfibrillar network in the iPP melt. During injection molding, the iPP molecules experienced confined flow in the microchannels or pores formed by the microfibrillar network, which could redistribute and homogenize the flow field of polymer melt. Addition of the compatibilizer, glycidyl methacrylate-grafted iPP, restrained the molecular orientation but facilitated preservation of oriented molecules due to the chemical bonds at the interface between PET microfibrils and iPP. The cooperative effects of in situ microfibrillar network and interfacial compatibilizer led to almost the same molecular orientation across the whole thickness of the injection-molded parts. Additionally, the content of {beta} crystals in different layers of injection-molded iPP parts depended on the combined effects of the molecular orientation, the amount of oriented crystals, and the crystallization time between 105 and 140 C. The presence of the interfacial compatibilizer facilitated formation of the {beta} crystals because of preservation of the oriented molecules.

  1. Analysis of batch-related influences on injection molding processes viewed in the context of electro plating quality demands

    NASA Astrophysics Data System (ADS)

    Siepmann, Jens P.; Wortberg, Johannes; Heinzler, Felix A.

    2016-03-01

    The injection molding process is mandatorily influenced by the viscosity of the material. By varying the material batch the viscosity of the polymer changes. For the process and part quality the initial conditions of the material in addition to the processing parameters define the process and product quality. A high percentage of technical polymers processed in injection molding is refined in a follow-up production step, for example electro plating. Processing optimized for electro plating often requires avoiding high shear stresses by using low injection speed and pressure conditions. Therefore differences in the material charges' viscosity occur especially in the quality related low shear rate area. These differences and quality related influences can be investigated by high detail rheological analysis and process simulation based on adapted material describing models. Differences in viscosity between batches can be detected by measurements with high-pressure-capillary-rheometers or oscillatory rheometers for low shear rates. A combination of both measurement techniques is possible by the Cox-Merz-Relation. The detected differences in the rheological behavior of both charges are summarized in two material behavior describing model approaches and added to the simulation. In this paper the results of processing-simulations with standard filling parameters are presented with two ABS charges. Part quality defining quantities such as temperature, pressure and shear stress are investigated and the influence of charge variations is pointed out with respect to electro plating quality demands. Furthermore, the results of simulations with a new quality related process control are presented and compared to the standard processing.

  2. 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.

  3. Unprecedented Development of Ultrahigh Expansion Injection-Molded Polypropylene Foams by Introducing Hydrophobic-Modified Cellulose Nanofibers.

    PubMed

    Wang, Long; Ishihara, Shota; Hikima, Yuta; Ohshima, Masahiro; Sekiguchi, Takafumi; Sato, Akihiro; Yano, Hiroyuki

    2017-03-22

    Herein, an ultrahigh 18-fold expansion of isotactic polypropylene (iPP)/cellulose nanofiber (CNF) nanocomposite foams was achieved for the first time using a core-back foam injection molding technique. It was found that CNFs were well dispersed and aligned along the cell wall in the core-back direction. Interestingly, the formations of a hybrid shish-kebab of CNFs and classic shish-kebab of PP were simultaneously achieved in the PP/CNF composites. Finally, we proposed that the combination of local strong melt strength, probably resulting from the strong alignment of CNFs and subsequent formation of hybrid shish-kebab structures, and weak melt strength in the unreinforced PP melt might be the driving force for remarkably enhancing the PP foamability.

  4. High-Temperature Oxidation Behavior of Two Nickel-Based Superalloys Produced by Metal Injection Molding for Aero Engine Applications

    NASA Astrophysics Data System (ADS)

    Albert, Benedikt; Völkl, Rainer; Glatzel, Uwe

    2014-09-01

    For different high-temperature applications like aero engines or turbochargers, metal injection molding (MIM) of superalloys is an interesting processing alternative. For operation at high temperatures, oxidation behavior of superalloys produced by MIM needs to match the standard of cast or forged material. The oxidation behavior of nickel-based superalloys Inconel 713 and MAR-M247 in the temperature interval from 1073 K to 1373 K (800 °C to 1100 °C) is investigated and compared to cast material. Weight gain is measured discontinuously at different oxidation temperatures and times. Analysis of oxidized samples is done via SEM and EDX-measurements. MIM samples exhibit homogeneous oxide layers with a thickness up to 4 µm. After processing by MIM, Inconel 713 exhibits lower weight gain and thinner oxide layers than MAR-M247.

  5. DNA barcoding via counterstaining with AT/GC sensitive ligands in injection-molded all-polymer nanochannel devices.

    PubMed

    Østergaard, Peter Friis; Matteucci, Marco; Reisner, Walter; Taboryski, Rafael

    2013-02-21

    Nanochannel technology, coupled with a suitable DNA labeling chemistry, is a powerful approach for performing high-throughput single-molecule mapping of genomes. Yet so far nanochannel technology has remained inaccessible to the broader research community due to high fabrication cost and/or requirement of specialized facilities/skill-sets. In this article we show that nanochannel-based mapping can be performed in all polymer chips fabricated via injection molding: a fabrication process so inexpensive that the devices can be considered disposable. Fluorescent intensity variations can be obtained from molecules extended in the polymer nanochannels via chemical counterstaining against YOYO-1. In particular, we demonstrate that the counterstaining induced fluorescent intensity variations to a large degree appear to be proportional to the theoretically computed sequence-maps of both local AT and GC variation along DNA sequences.

  6. Effect of low doses beta irradiation on micromechanical properties of surface layer of injection molded polypropylene composite

    NASA Astrophysics Data System (ADS)

    Manas, David; Manas, Miroslav; Gajzlerova, Lenka; Ovsik, Martin; Kratky, Petr; Senkerik, Vojtěch; Skrobak, Adam; Danek, Michal; Manas, Martin

    2015-09-01

    The influence of beta radiation on the changes in the structure and selected properties (mechanical and thermal) was proved. Using low doses of beta radiation for 25% glass fiber filled polypropylene and its influence on the changes of micromechanical properties of surface layer has not been studied in detail so far. The specimens of 25% glass fiber filled PP were made by injection molding technology and irradiated by low doses of beta radiation (0, 15 and 33 kGy). The changes in the microstructure and micromechanical properties of surface layer were evaluated using FTIR, SEM, WAXS and instrumented microhardness test. The results of the measurements showed considerable increase in micromechanical properties (indentation hardness, indentation elastic modulus) when low doses of beta radiation are used.

  7. Biocompatibility of metal injection molded versus wrought ASTM F562 (MP35N) and ASTM F1537 (CCM) cobalt alloys.

    PubMed

    Chen, Hao; Sago, Alan; West, Shari; Farina, Jeff; Eckert, John; Broadley, Mark

    2011-01-01

    We present a comparative analysis between biocompatibility test results of wrought and Metal Injection Molded (MIM) ASTM F562-02 UNS R30035 (MP35N) and F1537 UNS R31538 (CCM) alloy samples that have undergone the same generic orthopedic implant's mechanical, chemical surface pre-treatment, and a designed pre-testing sample preparation method. Because the biocompatibility properties resulting from this new MIM cobalt alloy process are not well understood, we conducted tests to evaluate cytotoxicity (in vitro), hemolysis (in vitro), toxicity effects (in vivo), tissue irritation level (in vivo), and pyrogenicity count (in vitro) on such samples. We show that our developed MIM MP35N and CCM materials and treatment processes are biocompatible, and that both the MIM and wrought samples, although somewhat different in microstructure and surface, do not show significant differences in biocompatibility.

  8. Influence of Processing Conditions on the Mechanical Behavior and Morphology of Injection Molded Poly(lactic-co-glycolic acid) 85:15.

    PubMed

    de Melo, Liliane Pimenta; Salmoria, Gean Vitor; Fancello, Eduardo Alberto; Roesler, Carlos Rodrigo de Mello

    2017-01-01

    Two groups of PLGA specimens with different geometries (notched and unnotched) were injection molded under two melting temperatures and flow rates. The mechanical properties, morphology at the fracture surface, and residual stresses were evaluated for both processing conditions. The morphology of the fractured surfaces for both specimens showed brittle and smooth fracture features for the majority of the specimens. Fracture images of the notched specimens suggest that the surface failure mechanisms are different from the core failure. Polarized light techniques indicated birefringence in all specimens, especially those molded with lower temperature, which suggests residual stress due to rapid solidification. DSC analysis confirmed the existence of residual stress in all PLGA specimens. The specimens molded using the lower injection temperature and the low flow rate presented lower loss tangent values according to the DMA and higher residual stress as shown by DSC, and the photoelastic analysis showed extensive birefringence.

  9. Influence of Processing Conditions on the Mechanical Behavior and Morphology of Injection Molded Poly(lactic-co-glycolic acid) 85:15

    PubMed Central

    Fancello, Eduardo Alberto

    2017-01-01

    Two groups of PLGA specimens with different geometries (notched and unnotched) were injection molded under two melting temperatures and flow rates. The mechanical properties, morphology at the fracture surface, and residual stresses were evaluated for both processing conditions. The morphology of the fractured surfaces for both specimens showed brittle and smooth fracture features for the majority of the specimens. Fracture images of the notched specimens suggest that the surface failure mechanisms are different from the core failure. Polarized light techniques indicated birefringence in all specimens, especially those molded with lower temperature, which suggests residual stress due to rapid solidification. DSC analysis confirmed the existence of residual stress in all PLGA specimens. The specimens molded using the lower injection temperature and the low flow rate presented lower loss tangent values according to the DMA and higher residual stress as shown by DSC, and the photoelastic analysis showed extensive birefringence. PMID:28848605

  10. Hydrophilic thermoplastic polyurethanes for the manufacturing of highly dosed oral sustained release matrices via hot melt extrusion and injection molding.

    PubMed

    Verstraete, G; Van Renterghem, J; Van Bockstal, P J; Kasmi, S; De Geest, B G; De Beer, T; Remon, J P; Vervaet, C

    2016-06-15

    Hydrophilic aliphatic thermoplastic polyurethane (Tecophilic™ grades) matrices for high drug loaded oral sustained release dosage forms were formulated via hot melt extrusion/injection molding (HME/IM). Drugs with different aqueous solubility (diprophylline, theophylline and acetaminophen) were processed and their influence on the release kinetics was investigated. Moreover, the effect of Tecophilic™ grade, HME/IM process temperature, extrusion speed, drug load, injection pressure and post-injection pressure on in vitro release kinetics was evaluated for all model drugs. (1)H NMR spectroscopy indicated that all grades have different soft segment/hard segment ratios, allowing different water uptake capacities and thus different release kinetics. Processing temperature of the different Tecophilic™ grades was successfully predicted by using SEC and rheology. Tecophilic™ grades SP60D60, SP93A100 and TG2000 had a lower processing temperature than other grades and were further evaluated for the production of IM tablets. During HME/IM drug loads up to 70% (w/w) were achieved. In addition, Raman mapping and (M)DSC results confirmed the homogenous distribution of mainly crystalline API in all polymer matrices. Besides, hydrophilic TPU based formulations allowed complete and sustained release kinetics without using release modifiers. As release kinetics were mainly affected by drug load and the length of the PEO soft segment, this polymer platform offers a versatile formulation strategy to adjust the release rate of drugs with different aqueous solubility. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Innovative use of wood-plastic-composites (WPC) as a core material in the sandwich injection molding process

    NASA Astrophysics Data System (ADS)

    Moritzer, Elmar; Martin, Yannick

    2016-03-01

    The demand for materials based on renewable raw materials has risen steadily in recent years. With society's increasing interest for climate protection and sustainability, natural-based materials such as wood-plastic-composites (WPC) have gained market share thanks to their positive reputation. Due to advantages over unreinforced plastics such as cost reduction and weight savings it is possible to use WPC in a wide area of application. Additionally, an increase in mechanical properties such as rigidity and strength is achieved by the fibers compared to unreinforced polymers. The combination of plastic and wood combines the positive properties of both components in an innovative material. Despite the many positive properties of wood-plastic-composite, there are also negative characteristics that prevent the use of WPC in many product areas, such as automotive interiors. In particular, increased water intake, which may result in swelling of near-surface particles, increased odor emissions, poor surface textures and distortion of the components are unacceptable for many applications. The sandwich injection molding process can improve this situation by eliminating the negative properties of WPC by enclosing it with a pure polymer. In this case, a layered structure of skin and core material is produced, wherein the core component is completely enclosed by the skin component. The suitability of WPC as the core component in the sandwich injection molding has not yet been investigated. In this study the possibilities and limitations of the use of WPC are presented. The consideration of different fiber types, fiber contents, skin materials and its effect on the filling behavior are the focus of the presented analysis.

  12. Shear flow and carbon nanotubes synergistically induced nonisothermal crystallization of poly(lactic acid) and its application in injection molding.

    PubMed

    Tang, Hu; Chen, Jing-Bin; Wang, Yan; Xu, Jia-Zhuang; Hsiao, Benjamin S; Zhong, Gan-Ji; Li, Zhong-Ming

    2012-11-12

    The effect of shear flow and carbon nanotubes (CNTs), separately and together, on nonisothermal crystallization of poly(lactic acid) (PLA) at a relatively large cooling rate was investigated by time-resolved synchrotron wide-angle X-ray diffraction (WAXD) and polarized optical microscope (POM). Unlike flexible-chain polymers such as polyethylene, and so on, whose crystallization kinetics are significantly accelerated by shear flow, neat PLA only exhibits an increase in onset crystallization temperature after experiencing a shear rate of 30 s(-1), whereas both the nucleation density and ultimate crystallinity are not changed too much because PLA chains are intrinsically semirigid and have relatively short length. The breaking down of shear-induced nuclei into point-like precursors (or random coil) probably becomes increasingly active after shear stops. Very interestingly, a marked synergistic effect of shear flow and CNTs exists in enhancing crystallization of PLA, leading to a remarkable increase of nucleation density in PLA/CNT nanocomposite. This synergistic effect is ascribed to extra nuclei, which are formed by the anchoring effect of CNTs' surfaces on the shear-induced nuclei and suppressing effect of CNTs on the relaxation of the shear-induced nuclei. Further, this interesting finding was deliberately applied to injection molding, aiming to improve the crystallinity of PLA products. As expected, a remarkable high crystallinity in the injection-molded PLA part has been achieved successfully by the combination of shear flow and CNTs, which offers a new method to fabricate PLA products with high crystallinity for specific applications.

  13. Easy alignment and effective nucleation activity of ramie fibers in injection-molded poly(lactic acid) biocomposites.

    PubMed

    Xu, Huan; Liu, Chun-Yan; Chen, Chen; Hsiao, Benjamin S; Zhong, Gan-Ji; Li, Zhong-Ming

    2012-10-01

    The poly(lactic acid) (PLA)/ramie fiber biocomposites were fabricated, which exhibited considerable reinforcement effect comparable to the glass fiber at the same loading. The attempts were made to understand the flow-induced morphology of ramie fibers and PLA crystals in the injection-molded PLA/ramie fiber biocomposites, thus revealing its relationship to biocomposite mechanical properties. The polarized optical microscopy (POM) and two-dimensional wide-angle X-ray diffraction (2D-WAXD) were for the first time used to determine the distribution of nature fibers, which interestingly showed the ramie fibers aligned well along the flow direction over the whole thickness of injection-molded parts, instead of skin-core structure. This easy alignment of ramie fibers during the common processing was ascribed to the intrinsically high flexibility of ramie fibers and strong interfacial interaction between PLA chains and cellulose molecules of ramie fibers. Both 2D-WAXD and differential scanning calorimeter (DSC) measurements suggested that the PLA matrix in its ramie biocomposites had rather high orientation degree and crystallinity, which was attributed to effective heterogeneous nucleation induced by ramie fibers and local shearing field in the vicinity of fiber surface. Remarkable improvement of mechanical and thermo-mechanical properties was achieved for PLA/ramie fiber biocomposites, without sacrifice of toughness and ductility. Addition of 30wt% ramie fibers increased the tensile strength and modulus of PLA/ramie fiber biocomposites from 65.6 and 1468 MPa for pure PLA to 91.3 and 2977 MPa, respectively. These superior mechanical properties were ascribed to easy alignment of ramie fibers, high crystallinity of PLA, and favorable interfacial adhesion as revealed by scanning electron microscopy (SEM) observation and theoretical analysis based on dynamic mechanical analysis (DMA) data. Copyright © 2012 Wiley Periodicals, Inc.

  14. Extruded/injection-molded composites containing unripe plantain flour, ethylene vinyl-alcohol and glycerol: Evaluation of color, mechanical property and biodegradability

    USDA-ARS?s Scientific Manuscript database

    Extruded/injection-molded composites were produced from plantain flour blended with ethylene vinyl-alcohol (EVA) and glycerol. Scanning electron microscopy showed composites had a smooth surface and excellent compatibility between plantain flour, EVA and glycerol. The impact of increased plantain fl...

  15. Simulation of mechanical behavior and optimization of simulated injection molding process for PLA based antibacterial composite and nanocomposite bone screws using central composite design.

    PubMed

    Heidari, Behzad Shiroud; Oliaei, Erfan; Shayesteh, Hadi; Davachi, Seyed Mohammad; Hejazi, Iman; Seyfi, Javad; Bahrami, Mozhgan; Rashedi, Hamid

    2017-01-01

    In this study, injection molding of three poly lactic acid (PLA) based bone screws was simulated and optimized through minimizing the shrinkage and warpage of the bone screws. The optimization was carried out by investigating the process factors such as coolant temperature, mold temperature, melt temperature, packing time, injection time, and packing pressure. A response surface methodology (RSM), based on the central composite design (CCD), was used to determine the effects of the process factors on the PLA based bone screws. Upon applying the method of maximizing the desirability function, optimization of the factors gave the lowest warpage and shrinkage for nanocomposite PLA bone screw (PLA9). Moreover, PLA9 has the greatest desirability among the selected materials for bone screw injection molding. Meanwhile, a finite element analysis (FE analysis) was also performed to determine the force values and concentration points which cause yielding of the screws under certain conditions. The Von-Mises stress distribution showed that PLA9 screw is more resistant against the highest loads as compared to the other ones. Finally, according to the results of injection molding simulations, the design of experiments (DOE) and structural analysis, PLA9 screw is recommended as the best candidate for the production of biomedical materials among all the three types of screws.

  16. The Influence of Injection Molding Parameter on Properties of Thermally Conductive Plastic

    NASA Astrophysics Data System (ADS)

    Hafizah Azis, N.; Zulafif Rahim, M.; Sa'ude, Nasuha; Rafai, N.; Yusof, M. S.; Tobi, ALM; Sharif, ZM; Rasidi Ibrahim, M.; Ismail, A. E.

    2017-05-01

    Thermally conductive plastic is the composite between metal-plastic material that is becoming popular because if it special characteristic. Injection moulding was regarded as the best process for mass manufacturing of the plastic composite due to its low production cost. The objective of this research is to find the best combination of the injection parameter setting and to find the most significant factor that effect the strength and thermal conductivity of the composite. Several parameter such as the volume percentage of copper powder, nozzle temperature and injection pressure of injection moulding machine were investigated. The analysis was done using Design Expert Software by implementing design of experiment method. From the analysis, the significant effects were determined and mathematical models of only significant effect were established. In order to ensure the validity of the model, confirmation run was done and percentage errors were calculated. It was found that the best combination parameter setting to maximize the value of tensile strength is volume percentage of copper powder of 3.00%, the nozzle temperature of 195°C and the injection pressure of 65%, and the best combination parameter settings to maximize the value of thermal conductivity is volume percentage of copper powder of 7.00%, the nozzle temperature of 195°C and the injection pressure of 65% as recommended..

  17. The effect of injection molding conditions on the near-surface rubber morphology, surface chemistry, and adhesion performance of semi-crystalline and amorphous polymers

    NASA Astrophysics Data System (ADS)

    Weakley-Bollin, Shannon Christine

    This thesis investigated the effect of injection molding processing variables, resin formulation and mold material on the resulting morphology and properties of semi-crystalline and amorphous polymers in parts molded on large presses with fully developed flow. Five different polymer resins and two different coating types were investigated, and the near-surface morphology was found to be dependent on material formulation, processing parameters, and geometry. For painted TPO, changes in the near-surface rubber morphology and surface chemistry based on material and processing conditions had no significant effect on the adhesion performance. For metal plated ABS, the adhesion performance was found to be heavily dependent on the rubber surface morphology, which varied with material formulation and processing conditions. One of the most significant findings was that forged aluminum injection molding tooling had little effect on the surface morphology or adhesion performance of either polypropylene or the two TPO formulations examined, despite the five-fold increase in thermal conductivity over traditional tool steel. Surface chemistry, however, was found to be affected by cooling rate, depending on material formulation. A UV stabilizer additive was found concentrated at 2.5 atomic percent on the surface of the aluminum molded part, but not the steel molded part, demonstrating a possible opportunity for using additives and aluminum tooling to create "designer surfaces". Processing conditions were found to have a competing role in metal plated ABS, where conditions that lowered surface stress and improved adhesion by a factor of 15 also increased the amount of bulk molded-in stress by nearly 7%. Both factors were found to play an important role in adhesion performance due to the effect of surface stress on the quality of the resulting etch structure. The bulk stress must be minimized to due to the large mechanical and thermal mismatch between the polymer and metal layers

  18. Ceramic micro-injection molded nozzles for serial femtosecond crystallography sample delivery

    DOE PAGES

    Beyerlein, K. R.; Adriano, L.; Heymann, M.; ...

    2015-12-08

    Serial femtosecond crystallography (SFX) using X-ray Free-Electron Lasers (XFELs) allows for room temperature protein structure determination without evidence of conventional radiation damage. In this method, a liquid suspension of protein microcrystals can be delivered to the X-ray beam in vacuum as a micro-jet, which replenishes the crystals at a rate that exceeds the current XFEL pulse repetition rate. Gas dynamic virtual nozzles produce the required micrometer-sized streams by the focusing action of a coaxial sheath gas and have been shown to be effective for SFX experiments. Here, we describe the design and characterization of such nozzles assembled from ceramic micro-injectionmore » molded outer gas-focusing capillaries. Trends of the emitted jet diameter and jet length as a function of supplied liquid and gas flow rates are measured by a fast imaging system. The observed trends are explained by derived relationships considering choked gas flow and liquidflow conservation. In conclusion, the performance of these nozzles in a SFX experiment is presented, including an analysis of the observed background.« less

  19. High solid loading aqueous base metal/ceramic feedstock for injection molding

    NASA Astrophysics Data System (ADS)

    Behi, Mohammad

    2001-07-01

    Increasing volume fraction of metal powder in feedstock provided lower shrinkage. Reduction of the shrinkage results in better dimensional precision. The rheology of the feedstock material plays an important role to allowing larger volume fractions of the metal powder to be incorporated in the feedstock formulations. The viscosity of the feedstock mainly depends on the binder viscosity, powder volume fraction and characteristics of metal powder. Aqueous polysaccharide agar was used as a baseline binder system for this study. The effect of several gel-strengthening additives on 1.5wt% and 2wt% agar gel was evaluated. A new gel-strengthening additive was found to be the most effective among the others. The effect of other additives such as glucose, sucrose and fructose on viscosity of baseline binder and feedstock was investigated. Two new agar based binder compositions were developed. The use of these new binder formulations significantly improved the volume fraction of the metal powder, the stability of the feedstock, and reduced the final shrinkage of the molded articles. Two types of 17-4PH stainless steel metal powders, one gas atomized and, the other water atomized, were used for this research.

  20. Formation of shish-kebabs in injection-molded poly(L-lactic acid) by application of an intense flow field.

    PubMed

    Xu, Huan; Zhong, Gan-Ji; Fu, Qiang; Lei, Jun; Jiang, Wei; Hsiao, Benjamin S; Li, Zhong-Ming

    2012-12-01

    Unlike polyolefins (e.g., isotactic polypropylene), it is still a great challenge to form rich shish-kebabs in biodegradable poly(L-lactic acid) (PLLA) because of its short chain length and semirigid chain backbone. In the present work, a modified injection molding technology, named oscillation shear injection molding, was applied to provide an intense shear flow on PLLA melt in mold cavity, in order to promote shear-induced crystallization of PLLA. Additionally, a small amount of poly(ethylene glycol) (PEG) with flexible chains was introduced for improving the crystallization kinetics. Numerous shish-kebabs of PLLA were achieved in injection-molded PLLA for the first time. High-resolution scanning electronic microscopy and small-angle X-ray scattering showed a structure feature of shish-kebabs with a diameter of around 0.7 μm and a long period of ~20 nm. The wide-angle X-ray diffraction results showed that shish-kebabs had more ordered crystalline structure of α-form. A significant improvement of the mechanical properties was obtained; the tensile strength and modulus increased to 73.7 and 1888 MPa from the initial values of 64.9 and 1684 MPa, respectively, meanwhile the ductility is not deteriorated. Interestingly, when shish-kebabs form in the PLLA/PEG system, a bamboo-like bionic structure comprising a hard skin layer and a soft core develops in injection-molded specimen. This unique structure leads to a great balance of mechanical properties, including substantial increments of 26, 20, and 112% in the tensile strength, modulus, and impact toughness, compared to the control sample. Further exploration will give a rich fundamental understanding in the shear-induced crystallization and morphology manipulation of PLLA, aiming to achieve superior PLLA products.

  1. Effect of Zr, Nb and Ti addition on injection molded 316L stainless steel for bio-applications: Mechanical, electrochemical and biocompatibility properties.

    PubMed

    Gulsoy, H Ozkan; Pazarlioglu, Serdar; Gulsoy, Nagihan; Gundede, Busra; Mutlu, Ozal

    2015-11-01

    The research investigated the effect of Zr, Nb and Ti additions on mechanical, electrochemical properties and biocompatibility of injection molded 316L stainless steel. Addition of elemental powder is promoted to get high performance of sintered 316L stainless steels. The amount of additive powder plays a role in determining the sintered microstructure and all properties. In this study, 316L stainless steel powders used with the elemental Zr, Nb and Ti powders. A feedstock containing 62.5 wt% powders loading was molded at different injection molded temperature. The binders were completely removed from molded components by solvent and thermal debinding at different temperatures. The debinded samples were sintered at 1350°C for 60 min. Mechanical, electrochemical property and biocompatibility of the sintered samples were performed mechanical, electrochemical, SBF immersion tests and cell culture experiments. Results of study showed that sintered 316L and 316L with additives samples exhibited high corrosion properties and biocompatibility in a physiological environment. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Characterization of thermoplastic polyurethane/polylactic acid (TPU/PLA) tissue engineering scaffolds fabricated by microcellular injection molding

    PubMed Central

    Mi, Hao-Yang; Salick, Max R.; Jing, Xin; Jacques, Brianna R.; Crone, Wendy C.; Peng, Xiang-Fang; Turng, Lih-Sheng

    2015-01-01

    Polylactic acid (PLA) and thermoplastic polyurethane (TPU) are two kinds of biocompatible and biodegradable polymers that can be used in biomedical applications. PLA has rigid mechanical properties while TPU possesses flexible mechanical properties. Blended TPU/PLA tissue engineering scaffolds at different ratios for tunable properties were fabricated via twin screw extrusion and microcellular injection molding techniques for the first time. Multiple test methods were used to characterize these materials. Fourier transform infrared spectroscopy (FTIR) confirmed the existence of the two components in the blends; differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) confirmed the immiscibility between the TPU and PLA. Scanning electron microscopy (SEM) images verified that, at the composition ratios studied, PLA was dispersed as spheres or islands inside the TPU matrix and that this phase morphology further influenced the scaffold’s microstructure and surface roughness. The blends exhibited a large range of mechanical properties that covered several human tissue requirements. 3T3 fibroblast cell culture showed that the scaffolds supported cell proliferation and migration properly. Most importantly, this study demonstrated the feasibility of mass producing biocompatible PLA/TPU scaffolds with tunable microstructures, surface roughnesses, and mechanical properties that have the potential to be used as artificial scaffolds in multiple tissue engineering applications. PMID:24094186

  3. A Comparative Analysis of Taguchi Methodology and Shainin System DoE in the Optimization of Injection Molding Process Parameters

    NASA Astrophysics Data System (ADS)

    Khavekar, Rajendra; Vasudevan, Hari, Dr.; Modi, Bhavik

    2017-08-01

    Two well-known Design of Experiments (DoE) methodologies, such as Taguchi Methods (TM) and Shainin Systems (SS) are compared and analyzed in this study through their implementation in a plastic injection molding unit. Experiments were performed at a perfume bottle cap manufacturing company (made by acrylic material) using TM and SS to find out the root cause of defects and to optimize the process parameters for minimum rejection. Experiments obtained the rejection rate to be 8.57% from 40% (appx.) during trial runs, which is quiet low, representing successful implementation of these DoE methods. The comparison showed that both methodologies gave same set of variables as critical for defect reduction, but with change in their significance order. Also, Taguchi methods require more number of experiments and consume more time compared to the Shainin System. Shainin system is less complicated and is easy to implement, whereas Taguchi methods is statistically more reliable for optimization of process parameters. Finally, experimentations implied that DoE methods are strong and reliable in implementation, as organizations attempt to improve the quality through optimization.

  4. Characterization of thermoplastic polyurethane/polylactic acid (TPU/PLA) tissue engineering scaffolds fabricated by microcellular injection molding.

    PubMed

    Mi, Hao-Yang; Salick, Max R; Jing, Xin; Jacques, Brianna R; Crone, Wendy C; Peng, Xiang-Fang; Turng, Lih-Sheng

    2013-12-01

    Polylactic acid (PLA) and thermoplastic polyurethane (TPU) are two kinds of biocompatible and biodegradable polymers that can be used in biomedical applications. PLA has rigid mechanical properties while TPU possesses flexible mechanical properties. Blended TPU/PLA tissue engineering scaffolds at different ratios for tunable properties were fabricated via twin screw extrusion and microcellular injection molding techniques for the first time. Multiple test methods were used to characterize these materials. Fourier transform infrared spectroscopy (FTIR) confirmed the existence of the two components in the blends; differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) confirmed the immiscibility between the TPU and PLA. Scanning electron microscopy (SEM) images verified that, at the composition ratios studied, PLA was dispersed as spheres or islands inside the TPU matrix and that this phase morphology further influenced the scaffold's microstructure and surface roughness. The blends exhibited a large range of mechanical properties that covered several human tissue requirements. 3T3 fibroblast cell culture showed that the scaffolds supported cell proliferation and migration properly. Most importantly, this study demonstrated the feasibility of mass producing biocompatible PLA/TPU scaffolds with tunable microstructures, surface roughnesses, and mechanical properties that have the potential to be used as artificial scaffolds in multiple tissue engineering applications.

  5. An Integrated Approach Linking Process to Structural Modeling With Microstructural Characterization for Injections-Molded Long-Fiber Thermoplastics

    SciTech Connect

    Nguyen, Ba Nghiep; Bapanapalli, Satish K.; Smith, Mark T.; Kunc, Vlastimil; Frame, Barbara; Norris, Robert E.; Phelps, Jay; Tucker III, Charles L.; Jin, Xiaoshi; Wang, Jin

    2008-09-01

    The objective of our work is to enable the optimum design of lightweight automotive structural components using injection-molded long fiber thermoplastics (LFTs). To this end, an integrated approach that links process modeling to structural analysis with experimental microstructural characterization and validation is developed. First, process models for LFTs are developed and implemented into processing codes (e.g. ORIENT, Moldflow) to predict the microstructure of the as-formed composite (i.e. fiber length and orientation distributions). In parallel, characterization and testing methods are developed to obtain necessary microstructural data to validate process modeling predictions. Second, the predicted LFT composite microstructure is imported into a structural finite element analysis by ABAQUS to determine the response of the as-formed composite to given boundary conditions. At this stage, constitutive models accounting for the composite microstructure are developed to predict various types of behaviors (i.e. thermoelastic, viscoelastic, elastic-plastic, damage, fatigue, and impact) of LFTs. Experimental methods are also developed to determine material parameters and to validate constitutive models. Such a process-linked-structural modeling approach allows an LFT composite structure to be designed with confidence through numerical simulations. Some recent results of our collaborative research will be illustrated to show the usefulness and applications of this integrated approach.

  6. Influence of thermal debinding on the final properties of Fe-Si soft magnetic alloys for metal injection molding (MIM)

    NASA Astrophysics Data System (ADS)

    Páez-Pavón, A.; Jiménez-Morales, A.; Santos, T. G.; Quintino, L.; Torralba, J. M.

    2016-10-01

    Metal injection molding (MIM) may be used to produce soft magnetic materials with optimal mechanical and magnetic properties. Unlike other techniques, MIM enables the production of complex and small Fe-Si alloy parts with silicon contents greater than 3% by weight. In MIM process development, it is critical to design a proper debinding cycle not only to ensure complete removal of the binder system but also to obtain improved properties in the final part. This work is a preliminary study on the production of Fe-3.8Si soft magnetic parts by MIM using pre-alloyed powders and a non-industrialized binder. Two different heating rates during thermal debinding were used to study their effect on the final properties of the part. The final properties of the sintered parts are related to thermal debinding. It has been demonstrated that the heating rate during thermal debinding has a strong influence on the final properties of Fe-Si soft magnetic alloys.

  7. Evaluation of the safety and efficiency of novel metallic implant scaler tips manufactured by the powder injection molding technique.

    PubMed

    Chun, Kyung A; Kum, Kee-Yeon; Lee, Woo-Cheol; Baek, Seung-Ho; Choi, Hae-Won; Shon, Won-Jun

    2017-07-11

    Although many studies have compared the properties of ultrasonic scaling instruments, it remains controversial as to which is most suitable for implant scaling. This study evaluated the safety and efficiency of novel metallic ultrasonic scaler tips made by the powder injection molding (PIM) technique on titanium surfaces. Mechanical instrumentation was carried out using four types of metal scaler tips consisting of copper (CU), bronze (BR), 316 L stainless steel (316 L), and conventional stainless steel (SS) tips. The instrumented surface alteration image of samples was viewed with scanning electron microscope (SEM) and surface profile of the each sample was investigated with confocal laser scanning microscopy (CLSM). Arithmetic mean roughness (Ra) and maximum height roughness (Rmax) of titanium samples were measured and dissipated power of the scaler tip was estimated for scaling efficiency. The average Ra values caused by the 316 L and SS tip were about two times higher than those of the CU and BR tips (p < 0.05). The Rmax value showed similar results. The efficiency of the SS tip was about 3 times higher than that of CU tip, the 316 L tip is about 2.7 times higher than that of CU tip, and the BR tip is about 1.2 times higher than that of CU tip. Novel metallic bronze alloy ultrasonic scaler tip minimally damages titanium surfaces, similar to copper alloy tip. Therefore, this bronze alloy scaler tip may be promising instrument for implant maintenance therapy.

  8. Galvanic corrosion of metal injection molded (MIM) and conventional brackets with nickel-titanium and copper-nickel-titanium archwires.

    PubMed

    Siargos, Barbara; Bradley, Thomas G; Darabara, Myrsini; Papadimitriou, George; Zinelis, Spiros

    2007-03-01

    To compare the galvanic coupling of conventional and metal injection molded (MIM) brackets with commonly used orthodontic archwires. Six of each type of bracket were suspended in lactic acid along with a sample of orthodontic wire (three nickel-titanium and three copper-nickel-titanium) for 28 days at 37 degrees C. The potential differences between the wires and brackets were recorded per second throughout the duration of the experiment. The MIM brackets exhibited potential differences similar to those seen for the conventional brackets. The greatest potential difference was found for MIM brackets with nickel-titanium wires (512 mV), whereas MIM brackets with copper-nickel-titanium wires had the smallest difference (115 mV). Scanning electron microscope (SEM)-energy-dispersive spectroscopic analysis of the tie-wing area of each bracket type indicated similar elemental composition in both brackets, but in slightly different percentages by weight. The MIM bracket exhibited extensive internal porosity, whereas the conventional bracket was more solid internally. The composition and manufacturing processes involved in fabricating MIM brackets impart corrosive properties similar to those seen in the bracket-wing area of conventional brackets and may provide a measurable benefit when taking into account the increased corrosion between the bracket and brazing alloy of conventional brackets.

  9. Improvement of the Dimensional Stability of Powder Injection Molded Compacts by Adding Swelling Inhibitor into the Debinding Solvent

    NASA Astrophysics Data System (ADS)

    Fan, Yang-Liang; Hwang, Kuen-Shyang; Su, Shao-Chin

    2008-02-01

    Defects are frequently found in powder injection molded (PIM) compacts during solvent debinding due to the swelling of the binders. This problem can be alleviated by adjusting the composition of the debinding solvent. In this study, 10 vol pct swelling inhibitors were added into heptane, and the in-situ amounts of swelling and sagging of the specimen in the solvent were recorded using a noncontacting laser dilatometer. The results show that the addition of ethanol, 2-propanol, 1-butanol, and 1-pentanol reduced the amounts of swelling by 31, 21, 17, and 11 pct, respectively. This was because the small molecule alcohols, which do not dissolve paraffin wax (PW) or stearic acid (SA) in the binder system, could diffuse easily into the specimen and increased the portion of the swelling inhibitor inside. The amount of the extracted PW and SA also decreased, but only by 8.3, 6.1, 4.3, and 2.4 pct, respectively. The solubility parameters of 1-bromopropane (n-PB) and ethyl acetate (EA) are between those of heptane and alcohols, and they also yielded a slight reduction in the amounts of swelling by 6 and 11 pct, respectively. These results suggest that to reduce defects caused by binder swelling during solvent debinding, alcohols with high solubility parameters can be added into heptane without sacrificing significantly on the debinding rate.

  10. Structure development of polypropylenes of varying stereoregular form and tacticity in melt spinning, tubular blown film extrusion and injection molding

    NASA Astrophysics Data System (ADS)

    Choi, Dongman

    2002-08-01

    Polypropylene has become an important commercial thermoplastic since the isotactic form was first synthesized in the 1950's by Natta and his coworkers using Ziegler's catalysts. In recent years, new types of polypropylenes different than the existing Ziegler-Natta polypropylenes have also been commercially available through the application of the improved catalysts, i.e. metallocene. These include isotactic polypropylenes possessing lower stereoregularities and syndiotactic polypropylene. In this dissertation, we study structure development in processing these new polypropylenes and conventional high tacticity isotactic polypropylenes. We begin with the study of formation of structure in crystallization from quiescent melts and investigation of the crystallization kinetics of these polypropylenes. These are carried out by both isothermal and non-isothermal experiments. Then, we turn to the study of structure development during processing of these polymers. This is carried out in three major polyolefin processing processes: (i) melt spinning, (ii) tubular blown film extrusion and (iii) injection molding. The crystal structure and orientation of fabricated samples were characterized by wide angle X-ray diffraction (WARD), birefringence and differential scanning calorimetry (DSC). We seek to correlate the formation of structure and orientation development with processing conditions (e.g. stress field and cooling rate) and material characters (e.g. tacticity and crystallization rate) and find processing-structure-properties relationships in processing these polymers.

  11. Preservation of Geometrical Integrity of Supersolidus-Liquid-Phase-Sintered SKD11 Tool Steels Prepared with Powder Injection Molding

    NASA Astrophysics Data System (ADS)

    Chuang, K. H.; Hwang, K. S.

    2011-07-01

    The powder injection molded SKD11 tool steels often manifest shape retention problems during supersolidus liquid phase sintering due to the difficulties in controlling the amount of liquid phase. The typical temperature range for the sintering of SKD11 is only 10 K, between 1503 and 1513 K (1230 and 1240 °C), and this narrow sintering range demands a special furnace with very uniform temperature distribution. Through the addition of carbides, in particular TiC, this problem is resolved by enlarging the liquid + γ + carbide region in the phase diagram and by impeding the grain growth with the carbides. The resulting sintering window is broadened to 40 K, between 1513 and 1553 K (1240 and 1280 °C). The relevant mechanisms on the improvement of shape retention are discussed with a focus on the effect of carbide addition on the changes in the phase diagram and the microstructure. A guideline for the selection of effective carbides is also proposed based on the experimental results and the phase diagram analyses.

  12. Microstructures, mechanical properties, and fracture behaviors of metal-injection molded 17-4PH stainless steel

    NASA Astrophysics Data System (ADS)

    Wu, Ming-Wei; Huang, Zeng-Kai; Tseng, Chun-Feng; Hwang, Kuen-Shyang

    2015-05-01

    Metal injection molding (MIM) is a versatile technique for economically manufacturing various metal parts with complicated shapes and excellent properties. The objective of this study was to clarify the effects of powder type (water-atomized and gas-atomized powders) and various heat treatments (sintering, solutioning, H900, and H1100) on the microstructures, mechanical properties, and fracture behaviors of MIM 17-4PH stainless steels. The results showed that better mechanical properties of MIM 17-4PH can be achieved with gas-atomized powder than with water-atomized powder due mainly to the lower silicon and oxygen contents and fewer SiO2 inclusions in the steels. The presence of 10 vol% δ ferrite does not impair the UTS or elongation of MIM 17-4PH stainless steels. The δ ferrite did not fracture, even though the neighboring martensitic matrix was severely cracked. Moreover, H900 treatment produces the highest hardness and UTS, along with moderate elongation. H1100 treatment produces the best elongation, along with moderate hardness and UTS.

  13. Thermoplastic polyurethanes for the manufacturing of highly dosed oral sustained release matrices via hot melt extrusion and injection molding.

    PubMed

    Claeys, Bart; Vervaeck, Anouk; Hillewaere, Xander K D; Possemiers, Sam; Hansen, Laurent; De Beer, Thomas; Remon, Jean Paul; Vervaet, Chris

    2015-02-01

    This study evaluated thermoplastic polyurethanes (TPUR) as matrix excipients for the production of oral solid dosage forms via hot melt extrusion (HME) in combination with injection molding (IM). We demonstrated that TPURs enable the production of solid dispersions - crystalline API in a crystalline carrier - at an extrusion temperature below the drug melting temperature (Tm) with a drug content up to 65% (wt.%). The release of metoprolol tartrate was controlled over 24h, whereas a complete release of diprophylline was only possible in combination with a drug release modifier: polyethylene glycol 4000 (PEG 4000) or Tween 80. No burst release nor a change in tablet size and geometry was detected for any of the formulations after dissolution testing. The total matrix porosity increased gradually upon drug release. Oral administration of TPUR did not affect the GI ecosystem (pH, bacterial count, short chain fatty acids), monitored via the Simulator of the Human Intestinal Microbial Ecosystem (SHIME). The high drug load (65 wt.%) in combination with (in vitro and in vivo) controlled release capacity of the formulations, is noteworthy in the field of formulations produced via HME/IM.

  14. The Evaluation of 3 Dimensional Polymerization Changes of a Denture Resin Utilizing Injection Molding with Water Bath Polymerization and Microwave Polymerization

    DTIC Science & Technology

    2016-06-01

    The Evaluation of 3-Dimensional Polymerization Changes of a Denture Resin Utilizing Injection Molding with Water Bath Polymerization and Microwave...methacrylate denture resin . Materials and Methods: The study used a randomized observational design. Thirty SLA master dies, in the form of a...groups and sequencing numbers for each group were recorded in a log (see 6.3.4). From the SLA master dies, 30 acrylic resin denture bases were

  15. Assessment of Current Process Modeling Approaches to Determine Their Limitations, Applicability and Developments Needed for Long-Fiber Thermoplastic Injection Molded Composites

    SciTech Connect

    Nguyen, Ba Nghiep; Holbery, Jim; Smith, Mark T.; Kunc, Vlastimil; Norris, Robert E.; Phelps, Jay; Tucker III, Charles L.

    2006-11-30

    This report describes the status of the current process modeling approaches to predict the behavior and flow of fiber-filled thermoplastics under injection molding conditions. Previously, models have been developed to simulate the injection molding of short-fiber thermoplastics, and an as-formed composite part or component can then be predicted that contains a microstructure resulting from the constituents’ material properties and characteristics as well as the processing parameters. Our objective is to assess these models in order to determine their capabilities and limitations, and the developments needed for long-fiber injection-molded thermoplastics (LFTs). First, the concentration regimes are summarized to facilitate the understanding of different types of fiber-fiber interaction that can occur for a given fiber volume fraction. After the formulation of the fiber suspension flow problem and the simplification leading to the Hele-Shaw approach, the interaction mechanisms are discussed. Next, the establishment of the rheological constitutive equation is presented that reflects the coupled flow/orientation nature. The decoupled flow/orientation approach is also discussed which constitutes a good simplification for many applications involving flows in thin cavities. Finally, before outlining the necessary developments for LFTs, some applications of the current orientation model and the so-called modified Folgar-Tucker model are illustrated through the fiber orientation predictions for selected LFT samples.

  16. Assessment of the hardness of different orthodontic wires and brackets produced by metal injection molding and conventional methods

    PubMed Central

    Alavi, Shiva; Kachuie, Marzie

    2017-01-01

    Background: This study was conducted to assess the hardness of orthodontic brackets produced by metal injection molding (MIM) and conventional methods and different orthodontic wires (stainless steel, nickel-titanium [Ni-Ti], and beta-titanium alloys) for better clinical results. Materials and Methods: A total of 15 specimens from each brand of orthodontic brackets and wires were examined. The brackets (Elite Opti-Mim which is produced by MIM process and Ultratrimm which is produced by conventional brazing method) and the wires (stainless steel, Ni-Ti, and beta-titanium) were embedded in epoxy resin, followed by grinding, polishing, and coating. Then, X-ray energy dispersive spectroscopy (EDS) microanalysis was applied to assess their elemental composition. The same specimen surfaces were repolished and used for Vickers microhardness assessment. Hardness was statistically analyzed with Kruskal–Wallis test, followed by Mann–Whitney test at the 0.05 level of significance. Results: The X-ray EDS analysis revealed different ferrous or co-based alloys in each bracket. The maximum mean hardness values of the wires were achieved for stainless steel (SS) (529.85 Vickers hardness [VHN]) versus the minimum values for beta-titanium (334.65 VHN). Among the brackets, Elite Opti-Mim exhibited significantly higher VHN values (262.66 VHN) compared to Ultratrimm (206.59 VHN). VHN values of wire alloys were significantly higher than those of the brackets. Conclusion: MIM orthodontic brackets exhibited hardness values much lower than those of SS orthodontic archwires and were more compatible with NiTi and beta-titanium archwires. A wide range of microhardness values has been reported for conventional orthodontic brackets and it should be considered that the manufacturing method might be only one of the factors affecting the mechanical properties of orthodontic brackets including hardness. PMID:28928783

  17. Assessment of the hardness of different orthodontic wires and brackets produced by metal injection molding and conventional methods.

    PubMed

    Alavi, Shiva; Kachuie, Marzie

    2017-01-01

    This study was conducted to assess the hardness of orthodontic brackets produced by metal injection molding (MIM) and conventional methods and different orthodontic wires (stainless steel, nickel-titanium [Ni-Ti], and beta-titanium alloys) for better clinical results. A total of 15 specimens from each brand of orthodontic brackets and wires were examined. The brackets (Elite Opti-Mim which is produced by MIM process and Ultratrimm which is produced by conventional brazing method) and the wires (stainless steel, Ni-Ti, and beta-titanium) were embedded in epoxy resin, followed by grinding, polishing, and coating. Then, X-ray energy dispersive spectroscopy (EDS) microanalysis was applied to assess their elemental composition. The same specimen surfaces were repolished and used for Vickers microhardness assessment. Hardness was statistically analyzed with Kruskal-Wallis test, followed by Mann-Whitney test at the 0.05 level of significance. The X-ray EDS analysis revealed different ferrous or co-based alloys in each bracket. The maximum mean hardness values of the wires were achieved for stainless steel (SS) (529.85 Vickers hardness [VHN]) versus the minimum values for beta-titanium (334.65 VHN). Among the brackets, Elite Opti-Mim exhibited significantly higher VHN values (262.66 VHN) compared to Ultratrimm (206.59 VHN). VHN values of wire alloys were significantly higher than those of the brackets. MIM orthodontic brackets exhibited hardness values much lower than those of SS orthodontic archwires and were more compatible with NiTi and beta-titanium archwires. A wide range of microhardness values has been reported for conventional orthodontic brackets and it should be considered that the manufacturing method might be only one of the factors affecting the mechanical properties of orthodontic brackets including hardness.

  18. Effect of reprocessing cycles on the degradation of polypropylene copolymer filled with talc or montmorillonite during injection molding process

    SciTech Connect

    Demori, R.; Mauler, R. S.; Ashton, E.; Weschenfelder, V. F.; Cândido, L. H. A.; Kindlein, W.

    2015-05-22

    Mechanical recycling of polymeric materials is a favorable technique resulting in economic and environmental benefits, especially in the case of polymers with a high production volume as the polypropylene copolymer (PP). However, recycling by reprocessing techniques can lead to thermal, mechanical or thermo-oxidative degradation that can affect the structure of the polymer and subsequently the material properties. PP filled with montmorillonite (MMT) or talc are widely produced and studied, however, its degradation reactions by reprocessing cycles are poorly studied so far. In this study, the effects of reprocessing cycles in the structure and in the properties of the PP/MMT and PP/Talc were evaluated. The samples were mixed with 5% talc or MMT Cloisite C15A in a twin-screw extrusion. After extrusion, this filled material was submitted to five reprocessing cycles through an injection molding process. In order to evaluate the changes induced by reprocessing techniques, the samples were characterized by DSC, FT-IR, Izod impact and tensile strength tests. The study showed that Young modulus, elongation at brake and Izod impact were not affected by reprocessing cycles, except when using talc. In this case, the elongation at brake reduced until the fourth cycle, showing rigidity increase. The DSC results showed that melting and crystallization temperature were not affected. A comparison of FT-IR spectra of the reprocessed indicated that in both samples, between the first and the fifth cycle, no noticeable change has occurred. Thus, there is no evidence of thermo oxidative degradation. In general, these results suggest that PP reprocessing cycles using MMT or talc does not change the material properties until the fifth cycle.

  19. Creating Drug Solubilization Compartments via Phase Separation in Multicomponent Buccal Patches Prepared by Direct Hot Melt Extrusion-Injection Molding.

    PubMed

    Alhijjaj, Muqdad; Bouman, Jacob; Wellner, Nikolaus; Belton, Peter; Qi, Sheng

    2015-12-07

    Creating in situ phase separation in solid dispersion based formulations to allow enhanced functionality of the dosage form, such as improving dissolution of poorly soluble model drug as well as being mucoadhesive, can significantly maximize the in vitro and in vivo performance of the dosage form. This formulation strategy can benefit a wide range of solid dosage forms for oral and alternative routes of delivery. This study using buccal patches as an example created separated phases in situ of the buccal patches by selecting the excipients with different miscibility with each other and the model drug. The quaternary dispersion based buccal patches containing PEG, PEO, Tween 80, and felodipine were prepared by direct hot melt extrusion-injection molding (HME-IM). The partial miscibility between Tween 80 and semicrystalline PEG-PEO led to the phase separation after extrusion. The Tween phases acted as drug solubilization compartments, and the PEG-PEO phase had the primary function of providing mucoadhesion and carrier controlled dissolution. As felodipine was preferably solubilized in the amorphous regions of PEG-PEO, the high crystallinity of PEG-PEO resulted in an overall low drug solubilizing capacity. Tween 80 was added to improve the solubilization capacity of the system as the model drug showed good solubility in Tween. Increasing the drug loading led to the supersaturation of drug in Tween compartments and crystalline drug dispersed in PEG-PEO phases. The spatial distribution of these phase-separated compartments was mapped using X-ray micro-CT, which revealed that the domain size and heterogeneity of the phase separation increased with increasing the drug loading. The outcome of this study provides new insights into the applicability of in situ formed phase separation as a formulation strategy for the delivery of poorly soluble drugs and demonstrated the basic principle of excipient selection for such technology.

  20. Injection molded component

    SciTech Connect

    James, Allister W; Arrell, Douglas J

    2014-09-30

    An intermediate component includes a first wall member, a leachable material layer, and a precursor wall member. The first wall member has an outer surface and first connecting structure. The leachable material layer is provided on the first wall member outer surface. The precursor wall member is formed adjacent to the leachable material layer from a metal powder mixed with a binder material, and includes second connecting structure.

  1. Energy-Saving Effect of the Add-on Energy Recovery System for Electric Motor Drive Systems in the Injection Molding Machine

    NASA Astrophysics Data System (ADS)

    Takahashi, Keisuke; Hiraki, Eiji; Tanaka, Toshihiko

    The regenerative energy from the motor drive systems used in the injection molding is consumed by resistors connected to the DC bus of the inverters. Recently the recovery systems of the regenerative energy with a bi-directional DC-DC converter and capacitors have been developed. In this paper a new control strategy of the EDLC based energy recovery system is proposed. The basic principle of the proposed control strategy and the power losses consumed in the energy recovery system are discussed in detail. The validity and practicability are confirmed by digital computer simulation.

  2. MOLDING APPARATUS

    DOEpatents

    Fleming, P.G.

    1963-10-01

    Molding apparatus capable of coating multiple elements each molding cycle is described. The apparatus comprises a centrally disposed reservoir penetrated by a plurality of circumferentially arranged and radially extending passageways. These passageways, in turn, communicate with passages in a separable annular member that retains selectively configured molds and mold seating arrangements. Each mold, which is readily removable from its respective seat, is adapted to retain an element therein in spaced relation to the interior of the mold by utilizing element positioning means within the mold seat and the mold so that coating material may flow about the entire outer surface of the element. (AEC)

  3. 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

    2017-07-04

    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.

  4. Rapid mold replication

    SciTech Connect

    Heestand, G.M.; Beeler, R.G. Jr.; Brown, D.L.

    1995-06-01

    The desire to reduce tooling costs have driven manufacturers to investigate new manufacturing methods and materials. In the plastics injection molding industry replicating molds to meet production needs is time consuming (up to 6 months) and costly in terms of lost business. We have recently completed a feasibility study demonstrating the capability of high rate Electron Beam Physical Vapor Deposition (EBPVD) in producing mold inserts in days, not months. In the current practice a graphite mandrel, in the shape of the insert`s negative image, was exposed to a jet of metal vapor atoms emanating from an electron beam heated source of an aluminum-bronze alloy. The condensation rate of the metal atoms on the mandrel was sufficient to allow the deposit to grow at over 30 {mu}m/min or 1.2 mils per minute. The vaporization process continued for approximately 14 hours after which the mandrel and deposit were removed from the EBPVD vacuum chamber. The mandrel and condensate were easily separated resulting in a fully dense aluminum-bronze mold insert about 2.5 cm or one inch thick. This mold was subsequently cleaned and drilled for water cooling passages and mounted on a fixture for operation in an actual injection molding machine. Results of the mold`s operation were extremely successful showing great promise for this technique. This paper describes the EBPVD feasibility demonstration in more detail and discusses future development work needed to bring this technique into practice.

  5. Study on Three-dimensional Structures in Injection-molded iPP/Poly(ethylene-co-octene) by Transmission Electron Microtomography

    NASA Astrophysics Data System (ADS)

    Ono, Michio; Nishioka, Hideo; Jinnai, Hiroshi; Nakajima, Ken; Nishi, Toshio

    A phase-separated structure of the injection-molded isotactic polypropylene (iPP)/poly(ethylene-co-octene) (EOR) binary blend was studied in three-dimension (3D) by transmission electron microtomography (TEMT). Highly oriented EOR domains along both flow- (FD) and transverse-to-flow (TD) directions resulting in stacking lamella-sheet like structures to normal direction (ND) were confirmed. Some irregularities in morphology and intervals between the EOR sheets, and thickness heterogeneity of the sheets, were observed more frequently in the TD rather than in the FD. Using the 3D information obtained by the TEMT, we have tried to elucidate massive anisotropy in linear thermal expansion coefficient (CLTE) along the injection directions in this blend. We found that the CLTE anisotropy was well correlated with the lamella-like sheets arrays and their irregularities.

  6. Optimization of Injection Molding Parameters for HDPE/TiO₂ Nanocomposites Fabrication with Multiple Performance Characteristics Using the Taguchi Method and Grey Relational Analysis.

    PubMed

    Pervez, Hifsa; Mozumder, Mohammad S; Mourad, Abdel-Hamid I

    2016-08-22

    The current study presents an investigation on the optimization of injection molding parameters of HDPE/TiO₂ nanocomposites using grey relational analysis with the Taguchi method. Four control factors, including filler concentration (i.e., TiO₂), barrel temperature, residence time and holding time, were chosen at three different levels of each. Mechanical properties, such as yield strength, Young's modulus and elongation, were selected as the performance targets. Nine experimental runs were carried out based on the Taguchi L₉ orthogonal array, and the data were processed according to the grey relational steps. The optimal process parameters were found based on the average responses of the grey relational grades, and the ideal operating conditions were found to be a filler concentration of 5 wt % TiO₂, a barrel temperature of 225 °C, a residence time of 30 min and a holding time of 20 s. Moreover, analysis of variance (ANOVA) has also been applied to identify the most significant factor, and the percentage of TiO₂ nanoparticles was found to have the most significant effect on the properties of the HDPE/TiO₂ nanocomposites fabricated through the injection molding process.

  7. Optimization of Injection Molding Parameters for HDPE/TiO2 Nanocomposites Fabrication with Multiple Performance Characteristics Using the Taguchi Method and Grey Relational Analysis

    PubMed Central

    Pervez, Hifsa; Mozumder, Mohammad S.; Mourad, Abdel-Hamid I.

    2016-01-01

    The current study presents an investigation on the optimization of injection molding parameters of HDPE/TiO2 nanocomposites using grey relational analysis with the Taguchi method. Four control factors, including filler concentration (i.e., TiO2), barrel temperature, residence time and holding time, were chosen at three different levels of each. Mechanical properties, such as yield strength, Young’s modulus and elongation, were selected as the performance targets. Nine experimental runs were carried out based on the Taguchi L9 orthogonal array, and the data were processed according to the grey relational steps. The optimal process parameters were found based on the average responses of the grey relational grades, and the ideal operating conditions were found to be a filler concentration of 5 wt % TiO2, a barrel temperature of 225 °C, a residence time of 30 min and a holding time of 20 s. Moreover, analysis of variance (ANOVA) has also been applied to identify the most significant factor, and the percentage of TiO2 nanoparticles was found to have the most significant effect on the properties of the HDPE/TiO2 nanocomposites fabricated through the injection molding process. PMID:28773830

  8. Use of acrylic sheet molds for elastomeric products

    NASA Technical Reports Server (NTRS)

    Heisman, R. M.; Koerner, A. E.; Messineo, S. M.

    1970-01-01

    Molds constructed of acrylic sheet are more easily machined than metal, are transparent to ensure complete filling during injection, and have smooth surfaces free of contamination. Technique eliminates flashing on molded parts and mold release agents.

  9. Plastic molds reduce cost of encapsulating electric cable connectors

    NASA Technical Reports Server (NTRS)

    Knott, D.

    1964-01-01

    Resin casting of the aluminum master pattern forms a plastic mold for encapsulating a cable connector. An elastomer is injected into the mold and cured. The mold is disassembled leaving an elastomeric encapsulation around the connector.

  10. 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.

  11. TOPICAL REVIEW: Review on micro molding of thermoplastic polymers

    NASA Astrophysics Data System (ADS)

    Heckele, M.; Schomburg, W. K.

    2004-03-01

    Molding of micro components from thermoplastic polymers has become a routinely used industrial production process. This paper describes both the more than 30-year-old history and the present state of development and applications. Hot embossing, injection molding, reaction injection molding, injection compression molding, thermoforming, and various types of tool fabrication are introduced and their advantages and drawbacks are discussed. In addition, design considerations, process limitations, and commercially available micro molding machines are presented.

  12. Mold Allergy

    MedlinePlus

    ... homes and in other buildings. Everyone breathes in mold spores in the air, but some people have an ... your immune system is overly-sensitive to specific mold spores and treats them as an allergen . When you ...

  13. Comparison of Ultrasonic Welding and Thermal Bonding for the Integration of Thin Film Metal Electrodes in Injection Molded Polymeric Lab-on-Chip Systems for Electrochemistry

    PubMed Central

    Matteucci, Marco; Heiskanen, Arto; Zór, Kinga; Emnéus, Jenny; Taboryski, Rafael

    2016-01-01

    We compare ultrasonic welding (UW) and thermal bonding (TB) for the integration of embedded thin-film gold electrodes for electrochemical applications in injection molded (IM) microfluidic chips. The UW bonded chips showed a significantly superior electrochemical performance compared to the ones obtained using TB. Parameters such as metal thickness of electrodes, depth of electrode embedding, delivered power, and height of energy directors (for UW), as well as pressure and temperature (for TB), were systematically studied to evaluate the two bonding methods and requirements for optimal electrochemical performance. The presented technology is intended for easy and effective integration of polymeric Lab-on-Chip systems to encourage their use in research, commercialization and education. PMID:27801809

  14. Comparison of Ultrasonic Welding and Thermal Bonding for the Integration of Thin Film Metal Electrodes in Injection Molded Polymeric Lab-on-Chip Systems for Electrochemistry.

    PubMed

    Matteucci, Marco; Heiskanen, Arto; Zór, Kinga; Emnéus, Jenny; Taboryski, Rafael

    2016-10-27

    We compare ultrasonic welding (UW) and thermal bonding (TB) for the integration of embedded thin-film gold electrodes for electrochemical applications in injection molded (IM) microfluidic chips. The UW bonded chips showed a significantly superior electrochemical performance compared to the ones obtained using TB. Parameters such as metal thickness of electrodes, depth of electrode embedding, delivered power, and height of energy directors (for UW), as well as pressure and temperature (for TB), were systematically studied to evaluate the two bonding methods and requirements for optimal electrochemical performance. The presented technology is intended for easy and effective integration of polymeric Lab-on-Chip systems to encourage their use in research, commercialization and education.

  15. Predictive Engineering Tools for Injection-Molded Long-Carbon-Fiber Thermoplastic Composites - FY 2014 First Quarterly Report

    SciTech Connect

    Nguyen, Ba Nghiep; Sanborn, Scott E.; Simmons, Kevin L.; Mathur, Raj N.; Sangid, Michael D.; Jin, Xiaoshi; Costa, Franco; Gandhi, Umesh N.; Mori, Steven; Tucker III, Charles L.

    2014-02-19

    The CRADA between PNNL, Autodesk, Toyota and Magna has been effective since October 28th, 2013. The whole team including CRADA and subcontract partners kicked off the project technically on November 1st, 2013. This report describes work performed during the first quarter of FY 2014. The following technical progresses have been made toward project milestones: 1) The project kickoff meeting was organized at PlastiComp, Inc. in Winona on November 13th, 2013 involving all the project partners. During this meeting the research plan and Gantt chart were discussed and refined. The coordination of the research activities among the partners was also discussed to ensure that the deliverables and timeline will be met. 2) Autodesk delivered a research version of ASMI to PNNL for process modeling using this tool under the project. PNNL installed this research version on a PNNL computer and tested it. Currently, PNNL is using ASMI to prepare the models for PlastiComp plaques. 3) PlastiComp has compounded long carbon-fiber reinforced polypropylene and polyamide 6,6 compounds for rheological and thermal characterization tests by the Autodesk laboratories in Melbourne, Australia. 4) Initial mold flow analysis was carried out by PlastiComp to confirm that the 3D complex part selected by Toyota as a representative automotive part is moldable. 5) Toyota, Magna, PlastiComp and PNNL finalized the planning for molding the Toyota 3D complex part. 6) Purdue University worked with PNNL to update and specify the test matrix for characterization of fiber length/orientation. 7) Purdue University developed tools to automate the data collection and analysis of fiber length and orientation measurements. 8) Purdue University designed and specified equipment to replace the need for equipment using the technology established by the University of Leeds at General Motors.

  16. Influence of Rubber Concentration on Angular deformation in Injection Molded Parts of Talc and Rubber Filled Polypropylene

    NASA Astrophysics Data System (ADS)

    Takahara, Tadayoshi; Koyama, Kiyohito

    The most popular resin material for automotive plastic parts is polypropylene, which includes talc for stiffness and heat-resistance and rubber for impact-resistance. The anisotropic thermal expansion coefficient is well documented for talc reinforced polypropylene, but there are very few technical papers for warpage. Therefore, using this kind of material and molding with an L-shaped cross section, the influence of rubber concentration on corner deformation was discussed in this study. The results of this study are as follows 1) L-shaped cross section specimens show that the corner deformation increases linearly in proportion to the increase of rubber concentration. 2) Plane shape specimens show that the shrinkage rates in the planar direction decrease linearly and the shrinkage rates in the thickness direction increase linearly. 3) The strains in each rubber concentration are calculated using Hooke's Law. This force that induces corner deformation is assumed as the shrinkage difference between the planar and thickness directions. The tendencies of calculated strains are qualitatively consistent with measured corner deformations. 4) The reason why corner deformation decreases linearly to rubber concentration is due to the fact that the shrinkage difference between the planar and thickness directions increases and the fact that the flexural modulus decreases linearly.

  17. Fiber orientation structures and mechanical properties of injection molded short glass fiber-reinforced nylon ribbed plates

    SciTech Connect

    Wire, S.L.; Hine, P.J.; Duckett, R.A.; O`Gara, J.G.

    1996-12-31

    The work presented in this paper, sponsored by General Motors, describes a study of injection moulded ribbed plates of short glass fibre-reinforced Nylon. Ribs have been placed both parallel and perpendicular to the injection direction in an attempt to simulate the likely geometry of an actual automotive part. The complex orientation structures developed within these ribbed samples during injection moulding have been determined within both the parallel and perpendicular ribs, and for the regions between these structures using an automated image analysis system developed in-house by our colleagues at the University of Leeds Instrumentation Group. This system allows the rapid measurement of accurate fibre orientation data over large sample areas (mm {times} mm) enabling thousands of fibre images to be sampled. Mechanical properties both between and underneath the rib structures have been measured using the ultrasonic immersion technique, and these have been compared with theoretical predictions, determined using the measured fibre orientation averages and simple composite models developed within this laboratory. In general the agreement between theory and experiment is excellent.

  18. MOLD POLLUTION

    EPA Science Inventory

    Mold pollution is the growth of molds in a building resulting in a negative impact on the use of that structure. The negative impacts generally fall into two categories: destruction of the structure itself and adverse health impacts on the building's occupants. It is estimated...

  19. Mold Charlatans.

    ERIC Educational Resources Information Center

    Woody, Daniel

    2002-01-01

    Offers a primer on toxic mold and its removal, warning against ignorant or unethical mold remediation companies and offering five considerations (checking references, considering the big picture, sampling more than the air, considering release, and considering the source) when hiring such services. (EV)

  20. Mold Charlatans.

    ERIC Educational Resources Information Center

    Woody, Daniel

    2002-01-01

    Offers a primer on toxic mold and its removal, warning against ignorant or unethical mold remediation companies and offering five considerations (checking references, considering the big picture, sampling more than the air, considering release, and considering the source) when hiring such services. (EV)

  1. MOLD POLLUTION

    EPA Science Inventory

    Mold pollution is the growth of molds in a building resulting in a negative impact on the use of that structure. The negative impacts generally fall into two categories: destruction of the structure itself and adverse health impacts on the building's occupants. It is estimated...

  2. Predictive Engineering Tools for Injection-Molded Long-Carbon-Fiber Thermoplastic Composites - Second FY 2015 Quarterly Report

    SciTech Connect

    Nguyen, Ba Nghiep; Fifield, Leonard S.; Kijewski, Seth A.; Sangid, Michael D.; Wang, Jin; Costa, Franco; Tucker, III, Charles L.; Mathur, Raj N.; Gandhi, Umesh N.; Mori, Steven

    2015-05-19

    validation and compared the predicted fiber orientations with the measured data provided by Purdue at Locations A, B, and C on these plaques. The 15% accuracy criterion based on evaluation of tensile and bending stiffness was used to assess the accuracy in fiber orientation predictions. 9) PNNL completed ASMI mid-plane analyses for all the PlastiComp plaques defined on the go/no-go list for fiber length distribution (FLD) model validation and compared the predicted length distributions with the measured data provided by Purdue at Locations A, B, and C on these plaques. The 15% accuracy criterion based on evaluation of tensile and bending stiffness was used to assess the accuracy in fiber orientation predictions. 10) PNNL tested the new ASMI version received from Autodesk in March 2015, examined and discussed 3D fiber orientation predictions for PlastiComp plaques. 11) PlastiComp, Inc. (PlastiComp), Toyota Research Institute North America (Toyota) and Magna Exteriors and Interiors Corporation (Magna) participated in discussions with team members on the go/no-go plan. Toyota continued the discussion with Magna on tool modification for molding the complex part in order to achieve the target fiber length in the part.

  3. Predictive Engineering Tools for Injection-Molded Long-Carbon-Fiber Thermoplastic Composites - FY 2015 First Quarterly Report

    SciTech Connect

    Nguyen, Ba Nghiep; Fifield, Leonard S.; Kijewski, Seth A.; Sangid, Michael D.; Wang, Jin; Jin, Xiaoshi; Costa, Franco; Tucker, III, Charles L.; Mathur, Raj N.; Gandhi, Umesh N.; Mori, Steven

    2015-01-29

    plan for the project and submitted the established plan to DOE. 9) PNNL performed ASMI mid-plane analyses for the fast-fill center-gated 30wt% LCF/PP and 50wt% LCF/PA66 plaques and compared the predicted fiber orientations with the measured data provided by Purdue at Locations A, B, and C on these plaques. 10) Based on discussions with the University of Illinois and Autodesk, PNNL proposed a procedure to adjust fiber orientation data for Location A of the center-gated plaques so that the data can be expressed and interpreted in the flow/cross-flow direction coordinate system. 11) PNNL tested the new ASMI version received from Autodesk, examined and discussed 3D fiber orientation predictions for PlastiComp plaques. 12) PlastiComp, Inc. (PlastiComp), Toyota Research Institute North America (Toyota) and Magna Exteriors and Interiors Corp. (Magna) participated in discussions with team members on the go/no-go plan and the issues related to fiber length measurements. Toyota continued the discussion with Magna on tool modification for molding the complex part in order to achieve the target fiber length in the part.

  4. 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%.

  5. 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.

  6. On the failure mode in dry and hygrothermally aged short fiber-reinforced injection-molded polyarylamide composites by acoustic emission

    NASA Astrophysics Data System (ADS)

    Czigány, T.; Mohd Ishak, Z. A.; Karger-Kocsis, J.

    1995-09-01

    The failure mode in injection-molded short glass (GF) and carbon fiber (CF) reinforced polyarylamide (PAR) composites was studied on compact tension (CT) specimens in as-received (AR), hygrothermally aged (HA) and re-dried (RD) states, respectively, using acoustic emission (AE) and fractography. A significant difference was revealed in the failure manner characterized by the cumulative run, amplitude and energy distribution of the AE events as a function of the water content of the composites. Furthermore, a correlation was found between the cumulative AE events up to the maximum load and the fracture toughness of the composites. It was shown that the fracture response and thus the failure behavior of the water-saturated PAR composites can be restored by drying. This fact indicates that the water absorption and desorption are of a purely physical nature, i.e. they are reversible processes. It was established that chopped fiber-reinforced PAR composites fail by matrix deformation along with fiber/matrix debonding in the crack initiation, whereas fiber pull-out becomes dominant in the crack propagation range. Water uptake shifts both the AE amplitude and energy curves toward lower values, a phenomenon attributed to plastification of the PAR matrix by water.

  7. Fabrication of balloon-expandable self-lock drug-eluting polycaprolactone stents using micro-injection molding and spray coating techniques.

    PubMed

    Liu, Shih-Jung; Chiang, Fu-Jun; Hsiao, Chao-Ying; Kau, Yi-Chuan; Liu, Kuo-Sheng

    2010-10-01

    The purpose of this report was to develop novel balloon-expandable self-lock drug-eluting poly(ε-caprolactone) stents. To fabricate the biodegradable stents, polycaprolactone (PCL) components were first fabricated by a lab-scale micro-injection molded machine. They were then assembled and hot-spot welded into mesh-like stents of 3 and 5 mm in diameters. A special geometry of the components was designed to self-lock the assembled stents and to resist the external pressure of the blood vessels after being expanded by balloons. Characterization of the biodegradable PCL stents was carried out. PCL stents exhibited comparable mechanical property to that of metallic stents. No significant collapse pressure reduction and weight loss of the stents were observed after being submerged in PBS for 12 weeks. In addition, the developed stent was coated with paclitaxel by a spray coating technique and the release characteristic of the drug was determined by an in vitro elution method. The high-performance liquid chromatography analysis showed that the biodegradable stents could release a high concentration of paclitaxel for more than 60 days. By adopting the novel techniques, we will be able to fabricate biodegradable drug-eluting PCL stents of different sizes for various cardiovascular applications.

  8. Increasing in the wear resistance of injection molds made of 1.2343 steel using Ti/TiN/TiCN/nc-TiCN:a-C/nc-TiC:a-C/a-C nanocomposite coating

    NASA Astrophysics Data System (ADS)

    Rupetsov, Velko; Mishev, Georgi; Dishliev, Stefan; Kopanov, Viktor; Chitanov, Vassiliy; Kolaklieva, Lilyana; Pashinski, Chavdar

    2017-02-01

    Injection molds used in production of plastic components are subject of heavy abrasion wear. The increase of their wear resistance significantly reduces the production cost. In the current work are presented research results of the wear resistance of injection molds made of steel 1.2343, coated with Ti/TiN/TiCN/nc-TiCN: a-C/nc-TiC:a -C/a-C. The study of the wear rate was done using the volumetric method and the influence of the trace length was investigated. The coating thickness, nanohardness, elastic modulus and adhesion were also tested. The coating was applied on unhardened ground specimens, hardened ground specimens and hardened polished specimens.

  9. Mechanical and degradation properties of biodegradable Mg strengthened poly-lactic acid composite through plastic injection molding.

    PubMed

    Butt, Muhammad Shoaib; Bai, Jing; Wan, Xiaofeng; Chu, Chenglin; Xue, Feng; Ding, Hongyan; Zhou, Guanghong

    2017-01-01

    Full biodegradable magnesium alloy (AZ31) strengthened poly-lactic acid (PLA) composite rods for potential application for bone fracture fixation were prepared by plastic injection process in this work. Their surface/interfacial morphologies, mechanical properties and vitro degradation were studied. In comparison with untreated Mg rod, porous MgO ceramic coating on Mg surface formed by Anodizing (AO) and micro-arc-oxidation (MAO)treatment can significantly improve the interfacial binding between outer PLA cladding and inner Mg rod due to the micro-anchoring action, leading to better mechanical properties and degradation performance of the composite rods.With prolonging immersion time in simulated body fluid (SBF) solution until 8weeks, the MgO porous coating were corroded gradually, along with the disappearance of original pores and the formation of a relatively smooth surface. This resulted in a rapidly reduction in mechanical properties for corresponding composite rods owing to the weakening of interfacial binding capacity. The present results indicated that this new PLA-clad Mg composite rods show good potential biomedical applications for implants and instruments of orthopedic inner fixation. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. Fabrication and assembling of a microfluidic optical stretcher polymeric chip combining femtosecond laser and micro injection molding technologies

    NASA Astrophysics Data System (ADS)

    Volpe, Annalisa; Ancona, Antonio; Trotta, Gianluca; Martínez Vázquez, Rebeca; Fassi, Irene; Osellame, Roberto

    2017-02-01

    Microfluidic optical stretchers are valuable optofluidic devices for studying single cell mechanical properties. These usually consist of a single microfluidic channel where cells, with dimensions ranging from 5 to 20 μm are trapped and manipulated through optical forces induced by two counter-propagating laser beams. Recently, monolithic optical stretchers have been directly fabricated in fused silica by femtosecond laser micromachining (FLM). Such a technology allows writing in a single step in the substrate volume both the microfluidic channel and the optical waveguides with a high degree of precision and flexibility. However, this method is very slow and cannot be applied to cheaper materials like polymers. Therefore, novel technological platforms are needed to boost the production of such devices on a mass scale. In this work, we propose integration of FLM with micro-injection moulding (μIM) as a novel route towards the cost-effective and flexible manufacturing of polymeric Lab-on-a-Chip (LOC) devices. In particular, we have fabricated and assembled a polymethylmethacrylate (PMMA) microfluidic optical stretcher by exploiting firstly FLM to manufacture a metallic mould prototype with reconfigurable inserts. Afterwards, such mould was employed for the production, through μIM, of the two PMMA thin plates composing the device. The microchannel with reservoirs and lodgings for the optical fibers delivering the laser radiation for cell trapping were reproduced on one plate, while the other included access holes to the channel. The device was assembled by direct fs-laser welding, ensuring sealing of the channel and avoiding thermal deformation and/or contamination.

  11. Development and evaluation of P/M processing techniques to improve and control the mechanical properties of metal injection molded parts

    NASA Astrophysics Data System (ADS)

    Sago, James Alan

    Metal Injection Molding (MIM) is one of the most rapidly growing areas of powder metallurgy (P/M) but the growth of MIM into new markets and more demanding applications is limited by two fundamental barriers, the availability of low cost metal powders and a lack of knowledge and understanding of how mechanical properties, especially toughness, are affected by the many parameters in the MIM process. The goals of this study were to investigate solutions to these challenges for MIM. Mechanical alloying (MA) is a technique which can produce a wide variety of powder compositions in a size range suited to MIM and in smaller batches. However MA typically suffers from low production volumes and long milling times. This study will show that a saucer mill can produce sizable volumes of MA powders in times typically less than an hour. The MA process was also used to produce powders of 17-4PH stainless steel and the NiTi shape memory alloy for a MIM feedstock. This study shows that the MA powder characteristics led to successful MIM processing of parts. Previous studies have shown that the toughness of individual MIM parts can vary widely within a single production run and from one producer to another. In the last part of the study a Design of Experiments (DOE) approach was used to evaluate the effects of MIM processing parameters on the mechanical properties. Analysis of Variance produced mathematical models for Charpy impact toughness, hardness, density, and carbon content. Tensile properties did not produce a good model due to processing problems. The models and recommendations for improving both toughness and reproducibility of toughness are presented.

  12. Mold and Health

    EPA Pesticide Factsheets

    Molds have the potential to cause health problems. Molds produce allergens (substances that can cause allergic reactions) and irritants. Inhaling or touching mold or mold spores may cause allergic reactions in sensitive individuals.

  13. Mold Testing or Sampling

    EPA Pesticide Factsheets

    In most cases, if visible mold growth is present, sampling is unnecessary. Since no EPA or other federal limits have been set for mold or mold spores, sampling cannot be used to check a building's compliance with federal mold standards.

  14. INGOT MOLD

    DOEpatents

    Mangold, A.J. Jr.; MaHaffey, J.W.; Reese, S.L.

    1958-04-29

    An improved ingot-mold assembly is described, consisting of a body having a cavity and a recess extending through to the bottom of the body from the cavity, and the bottom of the cavity having an internal shoulder extending downward and a plug having an external shoulder. The plug extends above the shoulders and below the bottom of the body.

  15. Curbing indoor mold growth with mold inhibitors

    Treesearch

    Carol A. Clausen; Vina W. Yang

    2004-01-01

    Environmentally acceptable mold inhibitors are needed to curb the growth of mold fungi in woodframe housing when moisture management measures fail. Excess indoor moisture can lead to rapid mold establishment which, in turn, can have deleterious affects on indoor air quality. Compounds with known mold inhibitory properties and low mammalian toxicity, such as food...

  16. Mold Infections of the Central Nervous System

    PubMed Central

    McCarthy, Matthew; Rosengart, Axel; Schuetz, Audrey N.; Kontoyiannis, Dimitrios P.; Walsh, Thomas J.

    2016-01-01

    The recent outbreak of exserohilum rostratum meningitis linked to epidural injections of methylprednisolone acetate has brought renewed attention to mold infections of the central nervous system (CNS).1 Although uncommon, these infections are often devastating and difficult to treat. This focused review of the epidemiologic aspects, clinical characteristics, and treatment of mold infections of the CNS covers a group of common pathogens: aspergillus, fusarium, and scedosporium species, molds in the order Mucorales, and dematiaceous molds. Infections caused by these pathogen groups have distinctive epidemiologic profiles, clinical manifestations, microbiologic characteristics, and therapeutic implications, all of which clinicians should understand. PMID:25006721

  17. Damage Tolerance of Resin Transfer Molded Composite Sandwich Constructions

    DTIC Science & Technology

    1999-05-01

    cost manufacturing techniques to produce panels included; resin transfer molding ( RTM ), vacuum assisted resin infusion/transfer molding ( VARTM ), co...analysis conducted revealed that in terms of failure characteristics, the RTM / VARTM processed sandwich composites yielded similar performance as those...injection VARTM and vacuum assisted compression molding (VACM). Detailed experimental impact studies were performed under three scenarios low velocity

  18. 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.

  19. Innovations in molding technologies for microfabrication

    NASA Astrophysics Data System (ADS)

    Benzler, Tobias; Piotter, Volker; Hanemann, Thomas; Mueller, K.; Norajitra, Prachai; Ruprecht, Robert; Hausselt, Juergen H.

    1999-08-01

    Micromolding is a key technology for the economic production of components for microsystems. It is applied in several manufacturing techniques including the LIGA process. Especially MicroInjection Molding allows cost-effective large-scale production of components for many applications to be used in microsystems technology. Using special molding machines, lateral dimensions in the micrometer range, structural details down to 200nm and maximum aspect ratios of more than 20 are achieved. Examples for applications are PSU-made housings for microfluidic systems or microcomponents made of PMMA for cardiac catheters. PC or LCP are appropriate materials for interconnection devices in microoptics and electronics. Other examples are injection molded lost plastic molds for electroforming or electroless plating of metal microstructures. An important economic factor is the optimization of the molding process and tool using different simulation techniques. Recently, novel techniques for manufacturing metal or ceramic microstructures were developed by adapting Powder Injection Molding to microtechnologies. Using commercially available feedstocks, microstructures were made of metals or ceramics. Rapid manufacturing of microcomponents is achieved by the so-called Photomolding process using reactive polymer resins as photocurable material and e.g. mold inserts fabricated by laser ablation. The addition of micro- or nanosized ceramics to the resin allows the molding of filled composite with enhanced mechanical properties. Subsequent debindering and sintering steps yield the pure ceramic microcomponents.

  20. Mold: Cleanup and Remediation

    MedlinePlus

    ... Program in Brief Related Issues Resources Quick Links Air Pollution & Respiratory Health Air Quality Asthma Mold What's New ... and mold problems in schools ... more Quick Links Air Pollution & Respiratory Health Air Quality Asthma Mold What's New ...

  1. Allergies, asthma, and molds

    MedlinePlus

    ... carpets, stuffed animals, books, and wallpaper can contain mold spores if they are in damp places. Outdoors, mold ... at less than 30% to 50% will keep mold spores down. Empty dehumidifiers daily and clean them often ...

  2. 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.

  3. Mold production for polymer optics

    NASA Astrophysics Data System (ADS)

    Boerret, Rainer; Raab, Jonas; Speich, Marco

    2014-09-01

    The fields of application for polymer optics are huge and thus the need for polymer optics is steadily growing. Most polymer optics are produced in high numbers by injection molding. Therefore molds and dies that fulfill special requirements are needed. Polishing is usually the last process in the common process chain for production of molds for polymer optics. Usually this process step is done manually by experienced polishers. Due to the small number of skilled professionals and health problems because of the monotonous work the idea was to support or probably supersede manual polishing. Polishing using an industrial robot as movement system enables totally new possibilities in automated polishing. This work focuses on the surface generation with a newly designed polishing setup and on the code generation for the robot movement. The process starts on ground surfaces and with different tools and polishing agents surfaces that fulfill the requirements for injection molding of optics can be achieved. To achieve this the attention has to be focused not only on the process itself but also on tool path generation. A proprietary software developed in the Centre for Optical Technologies in Aalen University allows the tool path generation on almost any surface. This allows the usage of the newly developed polishing processes on different surfaces and enables an easy adaption. Details of process and software development will be presented as well as results from different polishing tests on different surfaces.

  4. 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.

  5. Characterization of Stainless Steel 316L Feedstock for Metal Injection Molding (MIM) Using Waste Polystyrene and Palm Kernel Oil Binder System

    NASA Astrophysics Data System (ADS)

    Asmawi, R.; Ibrahim, M. H. I.; Amin, A. M.; Mustafa, N.

    2016-11-01

    This paper presents the homogeneity characterisation of MIM feedstock consisting Stainless steel alloy (316 L) powder mix with binder 60wt% of waste polystyrene and 40wt% palm kernel oil. It is one of a critical step that must be conducted in MIM process in order to have a feedstock that is homogeneous and moldable. Water atomised Stainless Steel powder was mixed with the newly developed binder system in a Brabender Plastograph EC rotary mixer. Several tests were performed to assess the homogeneity of the feedstock that was produced at 60 vol % powder loading . The 60 vol.% was chosen because the Critical Powder Volume Concentration (CPVC) of the Powder was found to be 64.8 vol.%. The tests conducted were feedstock density, binder burn-out, rheology and SEM morphology observation. Rheological results exhibited pseudoplastic or shear thinning flow behavior, where its viscosity decreased with increasing shear rate. The feedstock viscosity also decreased with increasing temperature and was found to be suitable for molding. From all the tests conducted, it was found that the feedstock shows good homogeneity and suitable for subsequent processes in MIM.

  6. Floods and Mold Growth

    EPA Pesticide Factsheets

    Mold growth may be a problem after flooding. Excess moisture in the home is cause for concern about indoor air quality primarily because it provides breeding conditions for pests, molds and other microorganisms.

  7. QUANTIFYING INDOOR MOLDS

    EPA Science Inventory

    There is growing awareness that indoor molds/fungi may be connected to such conditions as asthma, allergies, hemorrhaging, chronic rhinosinusitis, memory loss, and a symptom complex called sick-building-syndrome. In addition, molds cause frequently fatal nosocomical infections. ...

  8. QUANTIFYING INDOOR MOLDS

    EPA Science Inventory

    There is growing awareness that indoor molds/fungi may be connected to such conditions as asthma, allergies, hemorrhaging, chronic rhinosinusitis, memory loss, and a symptom complex called sick-building-syndrome. In addition, molds cause frequently fatal nosocomical infections. ...

  9. Mold After a Disaster

    MedlinePlus

    ... or other health care provider. Safely Preventing Mold Growth Clean up and dry out the building quickly ( ... Systems: A Guide for Building Owners and Managers Population-Specific Recommendations for Protection From Exposure to Mold ...

  10. Grinding technologies of small optical element molds

    NASA Astrophysics Data System (ADS)

    Katsuki, Masahide; Urushibata, Kazunori

    2003-05-01

    The high-precision grinding technology is making contribution in every field, which is especially remarkable in the optics-related field. Lenses for digital camera and projector, which are mass-produced, for instance, are molded by the injection molding machine and glass molding-press machine. Concerning materials of high-precision molds, nickel alloy is mainly used in plastic-molding. And brittle material such as tungsten carbide and ceramic is used in glass-molding because the molding temperature is generally high. High-precision machining of nickel alloy is possible with a single-crystal diamond tool. Brittle material is ground by means of a diamond wheel, etc. Glass is being widely used for the lenses and other optical elements due to its favorable characteristics and life. As a result, needs for advancement of the high-precision grinding technology are being heightened. In grinding of small, fine and complex profiles, consideration for wheel truing and wear is a key point. Also, as many optical mold products are convex, mold profile is mainly concave. Especially, grinding of a small-aperture mold with small radius of curvature is difficult. In other words, a wheel whose diameter is larger than the radius of curvature of a mold to be ground cannot be used, and use of a small-diameter wheel is required inevitably. Influence of wheel wear and wheel diameter input errors at creation of grinding program becomes large. To eliminate such errors, a cycle of grinding, measurement and compensation grinding is normally repeated in mold machining until the target accuracy is obtained. Recently, needs for molding optical elements of small body of non-revolution such as prism and cylinder lens are on the increase, in addition to the body of revolution including lens. As one example, we introduce the compensation grinding and its results when grinding molds for an extremely small-aperture lens used for optical communication and a cylindrical lens array used for semi

  11. Mold-Resistant Construction.

    ERIC Educational Resources Information Center

    Huckabee, Christopher

    2003-01-01

    Asserts that one of the surest ways to prevent indoor air quality and mold issues is to use preventive construction materials, discussing typical resistance to dealing with mold problems (usually budget-related) and describing mold-resistant construction, which uses concrete masonry, brick, and stone and is intended to withstand inevitable…

  12. Bleach Neutralizes Mold Allergens

    ERIC Educational Resources Information Center

    Science Teacher, 2005

    2005-01-01

    Researchers at National Jewish Medical and Research Center have demonstrated that dilute bleach not only kills common household mold, but may also neutralize the mold allergens that cause most mold-related health complaints. The study, published in the Journal of Allergy and Clinical Immunology, is the first to test the effect on allergic…

  13. Molds for cable dielectrics

    DOEpatents

    Roose, L.D.

    1996-12-10

    Molds for use in making end moldings for high-voltage cables are described wherein the dielectric insulator of a 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. 5 figs.

  14. Molds for cable dielectrics

    DOEpatents

    Roose, Lars D.

    1996-01-01

    Molds for use in making end moldings for high-voltage cables are described wherein the dielectric insulator of a 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.

  15. Molds in the Environment

    MedlinePlus

    ... so that your employer can take action to clean up and prevent mold growth. To find out more about mold, remediation of mold, or workplace safety and health guidelines and regulations, you may also want to contact your local (city, county, or state) health department. You should also ...

  16. Interactive Mold House Tour

    EPA Pesticide Factsheets

    Get a quick glimpse of some of the most important ways to protect your home from mold by this interactive tour of the Mold House. Room-by-room, you'll learn about common mold issues and how to address them.

  17. Mold and Children's Health.

    ERIC Educational Resources Information Center

    Tuscano, Antoinette

    1998-01-01

    Mold can seriously affect the health of children with asthma or allergies. Indoor air problems related to mold can be difficult to identify, but when several students who spend time in the same classroom area show allergic symptoms, it is important to consider mold and air quality. Failure to respond promptly can have serious consequences. (SM)

  18. Mold-Resistant Construction.

    ERIC Educational Resources Information Center

    Huckabee, Christopher

    2003-01-01

    Asserts that one of the surest ways to prevent indoor air quality and mold issues is to use preventive construction materials, discussing typical resistance to dealing with mold problems (usually budget-related) and describing mold-resistant construction, which uses concrete masonry, brick, and stone and is intended to withstand inevitable…

  19. Bleach Neutralizes Mold Allergens

    ERIC Educational Resources Information Center

    Science Teacher, 2005

    2005-01-01

    Researchers at National Jewish Medical and Research Center have demonstrated that dilute bleach not only kills common household mold, but may also neutralize the mold allergens that cause most mold-related health complaints. The study, published in the Journal of Allergy and Clinical Immunology, is the first to test the effect on allergic…

  20. Preliminary concepts for high-temperature mold heating and cooling

    SciTech Connect

    Larson, J.P.

    1990-12-01

    The feasibility and limitations of various methods for mold heating and cooling were investigated. Two methods were chosen for evaluation: electrical heating and water cooling, and electrical heating and heat pipe conduction cooling. A model mold of each method was built. Test results indicated that the electrical heating and circulated water cooling was the better method. An injection mold utilizing this method was fabricated and temperature-cycled between 300 and 770{degree}F. 1 ref., 2 figs., 7 tabs.

  1. Interface conditions of two-shot molded parts

    SciTech Connect

    Kisslinger, Thomas; Bruckmoser, Katharina Resch, Katharina; Lucyshyn, Thomas E-mail: guenter.langecker@unileoben.ac.at; Langecker, Guenter Ruediger E-mail: guenter.langecker@unileoben.ac.at; Holzer, Clemens

    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, 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.

  2. In vitro osteogenic cell proliferation, mineralization, and in vivo osseointegration of injection molded high-density polyethylene-based hybrid composites in rabbit animal model.

    PubMed

    Tripathi, Garima; Basu, Bikramjit

    2014-07-01

    The present work reports the biocompatibility property of injection molded HDPE-HA-Al2O3 hybrid composites. In vitro cytocompatibility results reveal that osteogenic cell viability and bone mineralization are favorably supported in a statistically significant manner on HDPE-20% HA-20% Al2O3 composite, in comparison to HDPE-40 wt.% HA or HDPE-40 wt.% Al2O3 The difference in cytocompatibility property is explained in terms of difference in substrate wettability/surface energy and importantly, both the cell proliferation at 7 days or bone mineralization at 21 days on HDPE-20% HA-20% Al2O3 composite are either comparable or better than sintered HA. The progressive healing of cylindrical femoral bone defects in rabbit animal model was assessed by implantation experiments over 1, 4 and 12 weeks. Based on the histological analysis as well as histomorphometrical evaluation, a better efficacy of HDPE-20% HA-20% Al2O3 over high-density polyethylene (HDPE) for bone regeneration and neobone formation at host bone-implant interface was established. Taken together, the present study unequivocally establishes that despite the presence of 20% Al2O3, HDPE-based hybrid composites are as biocompatible as HA in vitro or better than HDPE in vivo. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  3. Ultrasonically-assisted Polymer Molding: An Evaluation

    NASA Astrophysics Data System (ADS)

    Moles, Matthew; Roy, Anish; Silberschmidt, Vadim

    Energy reduction in extrusion and injection molding processes can be achieved by the introduction of ultrasonic energy. Polymer flow can be enhanced on application of ultrasonic vibration, which can reduce the thermal and pressure input requirements to produce the same molding; higher productivity may also be achieved. In this paper, a design of an ultrasound-assisted injection mold machine is explored. An extrusion-die design was augmented with a commercial 1.5 kW ultrasonic transducer and sonotrode designed to resonate close to 20 kHz with up to 100 μm vibration amplitude. The design was evaluated with modal and thermal analysis using finite-element analysis software. The use of numerical techniques, including computational fluid dynamics, fluid-structure interaction and coupled Lagrangian-Eulerian method, to predict the effect of ultrasound on polymer flow was considered. A sonotrode design utilizing ceramic to enhance thermal isolation was also explored.

  4. Immunotherapy for mold allergy.

    PubMed

    Coop, Christopher A

    2014-12-01

    The objective of this article is to review the available studies regarding mold immunotherapy. A literature search was conducted in MEDLINE to identify peer-reviewed articles related to mold immunotherapy using the following keywords: mold, allergy, asthma, and immunotherapy. In addition, references cited within these articles were also reviewed. Articles were selected based on their relevance to the topic. Allergic responses to inhaled mold antigens are a recognized factor in allergic rhinitis and asthma. There are significant problems with respect to the production of relevant allergen material for the diagnosis and treatment of mold allergy with immunotherapy. Mold allergens contain proteases and should not be mixed with other allergens for immunotherapy. Most of the immunotherapy studies focus on two molds, Alternaria and Cladosporium. There is a lack of randomized placebo-controlled trials when evaluating the efficacy of mold immunotherapy with trials only focusing on immunotherapy to Alternaria and Cladosporium. Additional studies are needed regarding mold allergy and immunotherapy focusing on which molds are important for causing allergic disease.

  5. 53. PRODUCTION MOLDS. THESE MOLDS ARE COPIES OF THE ORIGINAL ...

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

    53. PRODUCTION MOLDS. THESE MOLDS ARE COPIES OF THE ORIGINAL MOLDS IN THE MORAVIAN POTTERY AND TILE WORKS COLLECTION, AND ARE USED TO PRESS TILES. THE FACTORY KEEPS TEN PRODUCTION MOLDS FOR EACH IMAGE. THE ORIGINAL MOLDS ARE NOT USED IN PRODUCTION. - Moravian Pottery & Tile Works, Southwest side of State Route 313 (Swamp Road), Northwest of East Court Street, Doylestown, Bucks County, PA

  6. Precision molding techniques for optical waveguide devices

    NASA Astrophysics Data System (ADS)

    Kalveram, Stefan; Neyer, Andreas

    1997-09-01

    Single-mode optical waveguide devices with integrated fiber- alignment grooves have been fabricated by injection molding of structured substrates and by subsequent filling of the waveguide channels with higher refractive index polymer. The master forms of the microstructures have been micro-machined channels with higher refractive index polymers. The master forms of the microstructures have been micro-machined in silicon. A special injection molding tool has been developed to yield plastic substrate chips with high surface planarity and replicated microstructures with details in the submicron range. Hot embossing is a further technology applied for the fabrication of large area waveguide devices with integrated mirrors, mainly intended for optical backplane applications. The hot embossing tool is driven on an injection molding machine which is a more cost effective method than the acquisition of conventional hot embossing equipment. In this paper, the injection molding as well as the hot embossing tool will be described together with the process and the results in the field of passive components for optical telecommunications and datacommunications.

  7. Development of processes and techniques for molding thermally stable, fire-retardant, low-smoke-emitting polymeric materials

    NASA Technical Reports Server (NTRS)

    Silverman, B.

    1979-01-01

    All available newly developed nonmetallic thermally stable polymers were examined for the development of processes and techniques by compression molding, injection molding, or thermoforming cabin interior parts. Efforts were directed toward developing molding techniques of new polymers to economically produce usable nonmetallic molded parts. Data on the flame resistant characteristics of the materials were generated from pilot plant batches. Preliminary information on the molding characteristics of the various thermoplastic materials was obtained by producing actual parts.

  8. Guide to Molds at School.

    ERIC Educational Resources Information Center

    Healthy Schools Network, Inc., Albany, NY.

    Asserting that molds growing in schools can be harmful to children's health and learning, this guide offers information about the issue. It provides an overview of the basics, then addresses testing, types of molds, molds and health, monitoring schools for mold, mold prevention and clean-up tips for schools, and what parents should do if they…

  9. Guide to Molds at School.

    ERIC Educational Resources Information Center

    Healthy Schools Network, Inc., Albany, NY.

    Asserting that molds growing in schools can be harmful to children's health and learning, this guide offers information about the issue. It provides an overview of the basics, then addresses testing, types of molds, molds and health, monitoring schools for mold, mold prevention and clean-up tips for schools, and what parents should do if they…

  10. Molded Magnetic Article

    NASA Technical Reports Server (NTRS)

    Bryant, Robert G. (Inventor); Namkung, Min (Inventor); Wincheski, Russell A. (Inventor); Fulton, James P. (Inventor); Fox, Robert L. (Inventor)

    2000-01-01

    A molded magnetic article and fabrication method are provided. Particles of ferromagnetic material embedded in a polymer binder are molded under heat and pressure into a geometric shape. Each particle is an oblate spheroid having a radius-to-thickness aspect ratio approximately in the range of 15-30. Each oblate spheroid has flattened poles that are substantially in perpendicular alignment to a direction of the molding pressure throughout the geometric shape.

  11. Effects of Process Parameters on Replication Accuracy of Microinjection Molded Cyclic Olefins Copolymers Parts

    NASA Astrophysics Data System (ADS)

    Lin, Hsuan-Liang; Chen, Chun-Sheng; Lee, Ruey-Tsung; Chen, Shia-Chung; Chien, Rean-Der; Jeng, Ming-Chang; Hwang, Jiun-Ren

    2013-04-01

    In this study, the effects of various processing parameters of microinjection molding on the replication accuracy of the micro featured fluidic platform used for DNA/RNA tests are investigated. LIGA-like processes were utilized to prepare a silicon-based SU-8 photoresist, followed by electroforming to make a Ni-Co-based stamp. A cyclic olefin copolymer (COC) was used as the injection molding material. The molding parameters associated with the replication accuracy of micro channel parts were investigated. It was found that for microinjection molded devices, the replication accuracies of the imprint width and depth increase with increasing of mold temperature, melt temperature, injection velocity, and packing pressure.

  12. BRITISH MOLDING MACHINE, PBQ AUTOMATIC COPE AND DRAG MOLDING MACHINE ...

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

    BRITISH MOLDING MACHINE, PBQ AUTOMATIC COPE AND DRAG MOLDING MACHINE MAKES BOTH MOLD HALVES INDIVIDUALLY WHICH ARE LATER ROTATED, ASSEMBLED, AND LOWERED TO POURING CONVEYORS BY ASSISTING MACHINES. - Southern Ductile Casting Company, Casting, 2217 Carolina Avenue, Bessemer, Jefferson County, AL

  13. BRITISH MOLDING MACHINE, PBQ AUTOMATIC COPE AND DRAG MOLDING MACHINE ...

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

    BRITISH MOLDING MACHINE, PBQ AUTOMATIC COPE AND DRAG MOLDING MACHINE MAKES BOTH MOLD HALVES INDIVIDUALLY WHICH ARE LATER ROTATED, ASSEMBLED, AND LOWERED TO POURING CONVEYORS BY ASSISTING MACHINES. - Southern Ductile Casting Company, Casting, 2217 Carolina Avenue, Bessemer, Jefferson County, AL

  14. Manufacturing injection-moleded Fresnel lens parquets for point-focus concentrating photovoltaic systems

    SciTech Connect

    Peters, E.M.; Masso, J.D.

    1995-10-01

    This project involved the manufacturing of curved-faceted, injection-molded, four-element Fresnel lens parquets for concentrating photovoltaic arrays. Previous efforts showed that high-efficiency (greater than 82%) Fresnel concentrators could be injection molded. This report encompasses the mold design, molding, and physical testing of a four-lens parquet for a solar photovoltaic concentrator system.

  15. Mold design with simulation for chalcogenide glass precision molding

    NASA Astrophysics Data System (ADS)

    Zhang, Yunlong; Wang, Zhibin; Li, Junqi; Zhang, Feng; Su, Ying; Wang, Zhongqiang

    2016-10-01

    Compare with the manufacturing of the traditional infrared material, such as signal crystal germanium, zinc sulfide, zinc selenide etc, chalcogenide infrared glass is suitable for precision molding for the low soften temperature to have large mass industry production. So the researches of precision glass molding are necessary, especially for the fast development of infrared product. The mold design is one of the key technologies of precision glass molding. In this paper, the mold processing of a sample chalcogenide glass from the technical drawing, mold design, molding to the lens are introduced. From the result of the precision molding, the technology of finite element simulation is a useful way to guiding the mold design. The molded lens by using mold process fit the design requirement.

  16. Silicon micro-mold

    DOEpatents

    Morales, Alfredo M.

    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.

  17. Glass molding process with mold lubrication

    DOEpatents

    Davey, Richard G.

    1978-06-27

    Improvements are provided in glass forming processes of the type wherein hot metal blank molds are employed by using the complementary action of a solid film lubricant layer, of graphite dispersed in a cured thermoset organopolysiloxane, along with an overspray of a lubricating oil.

  18. 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

  19. Resin film infusion mold tooling and molding method

    NASA Technical Reports Server (NTRS)

    Burgess, Roger (Inventor); Grossheim, Brian (Inventor); Mouradian, Karbis (Inventor); Thrash, Patrick J. (Inventor)

    1999-01-01

    A mold apparatus and method for resin film infusion molding including an outer mold tool having a facing sheet adapted to support a resin film and preform assembly. The facing sheet includes attachment features extending therefrom. An inner mold tool is positioned on the facing sheet to enclose the resin film and preform assembly for resin film infusion molding. The inner mold tool includes a plurality of mandrels positioned for engagement with the resin film and preform assembly. Each mandrel includes a slot formed therein. A plurality of locating bars cooperate with the slots and with the attachment features for locating the mandrels longitudinally on the outer mold tool.

  20. 92. PRODUCTION MOLDS. THESE MOLDS ARE COPIES OF THE ORIGINAL ...

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

    92. PRODUCTION MOLDS. THESE MOLDS ARE COPIES OF THE ORIGINAL MOLDS IN THE MORAVIAN POTTERY AND TILE WORKS COLLECTION, AND ARE USED TO PRESS TILES. THE FACTORY KEEPS TEN PRODUCTION MOLDS FOR EACH IMAGE. THE ORIGINAL MOLDS ARE NOT USED IN PRODUCTION. SAME VIEW AS PA-107-53. - Moravian Pottery & Tile Works, Southwest side of State Route 313 (Swamp Road), Northwest of East Court Street, Doylestown, Bucks County, PA

  1. Breaking the Mold.

    ERIC Educational Resources Information Center

    Huckabee, Christopher

    2003-01-01

    Using the example of a Texas elementary school, describes how to eliminate mold and mildew from school facilities, including discovering the problem, responding quickly, reconstructing the area, and crisis planning and prevention. (EV)

  2. Breaking the Mold.

    ERIC Educational Resources Information Center

    Huckabee, Christopher

    2003-01-01

    Using the example of a Texas elementary school, describes how to eliminate mold and mildew from school facilities, including discovering the problem, responding quickly, reconstructing the area, and crisis planning and prevention. (EV)

  3. MOLDS FOR CASTING PLUTONIUM

    DOEpatents

    Anderson, J.W.; Miley, F.; Pritchard, W.C.

    1962-02-27

    A coated mold for casting plutonium comprises a mold base portion of a material which remains solid and stable at temperatures as high as the pouring temperature of the metal to be cast and having a thin coating of the order of 0.005 inch thick on the interior thereof. The coating is composed of finely divided calcium fluoride having a particle size of about 149 microns. (AEC)

  4. 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.

  5. Multilevel micro-structuring of glassy carbon molds for precision glass molding

    NASA Astrophysics Data System (ADS)

    Prater, Karin; Dukwen, Julia; Scharf, Toralf; Herzig, Hans Peter; Plöger, Sven; Hermerschmidt, Andreas

    2015-09-01

    Replication techniques for diffractive optical elements (DOEs) in soft materials such as plastic injection molding are state of the art. For precision glass molding in glasses with high transition temperatures, molds with extreme thermal resistivity, low chemical reactivity and high mechanical strength are needed. Glassy Carbon can be operated up to 2000°C making it possible to mold almost all glasses including Fused Silica with a transition temperatures above 1060°C. For the structuring of Glassy Carbon wafers photolithography and a RIE process is used. We have developed a process using Si as a hard mask material. If the flow rates of the etching gases O2 and SF6 are chosen properly, high selectivity of GC to Si 19:1 can be achieved, which provides excellent conditions to realize high resolution elements with feature size down to 1 micron and fulfills requirements for optical applications. We fabricated several multilevel GC molds with 8 levels of structuring. Two different optical functionalities were implemented: 6x6 array beamsplitter and 1x4 linear beamsplitter. The molds were applied for precision glass molding of a low Tg glass L-BAL 42 (from Ohara) with a transition temperature of 565°C. Their optical performance was measured. A more detailed analysis of the impact of mold fabrication defects on optical performance is done. Rigorous coupled wave analysis simulations are performed, where we included fabrication constrains such as duty cycle, edge depth errors, wall verticality and misalignment errors. We will compare the results with the design specifications and discuss the influence of fabrication errors introduced during the different process steps.

  6. High-throughput plastic microlenses fabricated using microinjection molding techniques

    NASA Astrophysics Data System (ADS)

    Appasamy, Sreeram; Li, Weizhuo; Lee, Se Hwan; Boyd, Joseph T.; Ahn, Chong H.

    2005-12-01

    A novel fabrication scheme to develop high-throughput plastic microlenses using injection-molding techniques is realized. The initial microlens mold is fabricated using the well-known reflow technique. The reflow process is optimized to obtain reliable and repeatable microlens patterns. The master mold insert for the injection-molding process is fabricated using metal electroforming. The electroplating process is optimized for obtaining a low stress electroform. Two new plastic materials, cyclo olefin copolymer (COC) and Poly IR 2 are introduced in this work for fabricating microlenses. The plastic microlenses have been characterized for their focal lengths that range from 200 µm to 1.9 mm. This technique enables high-volume production of plastic microlenses with cycle times for a single chip being of the order of 60 s.

  7. FILLING MOLDS MADE ON THE BRITISH MOLDING MACHINE, AUTOMATIC COPE ...

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

    FILLING MOLDS MADE ON THE BRITISH MOLDING MACHINE, AUTOMATIC COPE AND DRAG (BMM) FROM MOBILE LADLE. EMPTY BULL LADLE IN FOREGROUND. - Southern Ductile Casting Company, Casting, 2217 Carolina Avenue, Bessemer, Jefferson County, AL

  8. TENDING THE MOLD, DURING THE TRANSFER FROM TUNDISH TO MOLD ...

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

    TENDING THE MOLD, DURING THE TRANSFER FROM TUNDISH TO MOLD TO CONTAINMENT CHAMBER IS CONTINUOUS CASTING OPERATOR, CALVIN ANDERS. - U.S. Steel, Fairfield Works, Continuous Caster, Fairfield, Jefferson County, AL

  9. Pressure molding of powdered materials improved by rubber mold insert

    NASA Technical Reports Server (NTRS)

    1964-01-01

    Pressure molding tungsten microspheres is accomplished by applying hydraulic pressure to a silicone rubber mold insert with several barrel shaped chambers which is placed in a steel die cavity. This technique eliminates castings containing shear fractures.

  10. Molding process for imidazopyrrolone polymers

    NASA Technical Reports Server (NTRS)

    Johnson, C. L. (Inventor)

    1973-01-01

    A process is described for producing shaped articles of imidazopyrrolone polymers comprising molding imidazopyrrolone polymer molding power under pressure and at a temperature greater than 475 C. Moderate pressures may be employed. Preferably, prior to molding, a preform is prepared by isostatic compression. The preform may be molded at a relatively low initial pressure and temperature; as the temperature is increased to a value greater than 475 C., the pressure is also increased.

  11. End moldings for cable dielectrics

    DOEpatents

    Roose, Lars D.

    2000-01-01

    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 is 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.

  12. REFRACTORY COATING FOR GRAPHITE MOLDS

    DOEpatents

    Stoddard, S.D.

    1958-06-24

    Refractory coating for graphite molds used in the casting of uranium is described. The coating is an alumino-silicate refractory composition which may be used as a mold surface in solid form or as a coating applied to the graphite mold. The composition consists of a mixture of ball clay, kaolin, alumina cement, alumina, water, sodium silicate, and sodium carbonate.

  13. Mold Allergy: Proper Humidifier Care

    MedlinePlus

    ... can be a major source of mold and mold spores. Learn how to keep a humidifier clean and reduce or eliminate this common allergen. CAUTION: Use of a humidifier or vaporizer can increase dust mite and mold growth. Frequent use of a humidifier or vaporizer ...

  14. Development of In-Mold Assembly Methods for Producing Mesoscale Revolute Joints

    DTIC Science & Technology

    2009-01-01

    positioning methods to realize cavity shape change to avoid damage to delicate mesoscale parts created during molding, (3) developing a method to...premolded component, this process may lead to irreparable damages to the first stage part. As a result, cavity morphing methods are the only feasible... damage to the part. Figure 4.3 Mold design iterations for second stage injection When the mesoscale pin is molded first, there is a concern that the

  15. MOLDED SEALING ELEMENT

    DOEpatents

    Bradford, B.W.; Skinner, W.J.

    1959-03-24

    Molded sealing elements suitable for use under conditions involving exposure to uranium hexafluoride vapor are described. Such sealing elements are made by subjecting graphitic carbons to a preliminary treatment with uranium hexafluoride vapor, and then incorporating polytetrafluorethylene in them. The resulting composition has good wear resistant and frictional properties and is resistant to disintegration by uranium hexafluoride over long periods of exposure.

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

    SciTech Connect

    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.

  17. Nonpost mold cure compound

    NASA Astrophysics Data System (ADS)

    Hirata, Akihiro

    1997-08-01

    The recent low price trend of electronic products has made IC manufacturing efficiency a top priority in the semiconductor industry. Post mold cure (PMC) process, which generally involves heating the packages in the oven at 175 C for 4 to 8 hours, takes up much longer time than most other assembly processes. If this PMC process can be reduced or eliminated, semiconductor makers will be rewarded with a much higher cost merit. We define the purpose of Non-PMC as 'to get high reliability with suitable physical and electrical properties without PMC'. We compared carious properties of molding compound before and after PMC. We found that curing reaction has almost complete through DSC and C-NMR measurement, but several properties have not stabilized yet, and that not all properties after PMC were better than before PMC. We developed new grade of molding compound considering these facts. And we found that main factors to accomplish non-PMC compound are curability and flowability, and more, increasing of fundamental properties. To accomplish non-PMC, at first, molding compound need to have very high curability. Generally speaking, too high curability causes low flowability, and causes incomplete filing, wire sweep, pad shift, and weak adhesion to inner parts of IC packages. To prevent these failures, various compound properties were studied, and we achieved in adding good flowability to very high curable molding compound. Finally, anti-popcorn property was improved by adding low moisture, high adhesion, high Tg, and high flexural strengths at high temperature. Through this study, we developed new compound grade for various package, especially large QFP using standard ECN resin.

  18. Micro-optical fabrication by ultraprecision diamond machining and precision molding

    NASA Astrophysics Data System (ADS)

    Li, Hui; Li, Likai; Naples, Neil J.; Roblee, Jeffrey W.; Yi, Allen Y.

    2017-06-01

    Ultraprecision diamond machining and high volume molding for affordable high precision high performance optical elements are becoming a viable process in optical industry for low cost high quality microoptical component manufacturing. In this process, first high precision microoptical molds are fabricated using ultraprecision single point diamond machining followed by high volume production methods such as compression or injection molding. In the last two decades, there have been steady improvements in ultraprecision machine design and performance, particularly with the introduction of both slow tool and fast tool servo. Today optical molds, including freeform surfaces and microlens arrays, are routinely diamond machined to final finish without post machining polishing. For consumers, compression molding or injection molding provide efficient and high quality optics at extremely low cost. In this paper, first ultraprecision machine design and machining processes such as slow tool and fast too servo are described then both compression molding and injection molding of polymer optics are discussed. To implement precision optical manufacturing by molding, numerical modeling can be included in the future as a critical part of the manufacturing process to ensure high product quality.

  19. Mold Heating and Cooling Pump Package Operator Interface Controls Upgrade

    SciTech Connect

    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 low residual stresses. The products fabricated are used on multiple programs.

  20. Replication and molding of optical components; Proceedings of the Meeting, Los Angeles, CA, Jan. 13, 14, 1988

    NASA Astrophysics Data System (ADS)

    Riedl, Max J.

    1988-01-01

    Various papers on the replication and molding of optical components are presented. Individual topics discussed include: advantages and limitations of epoxy replication, protecting optical replication models with hard carbon, aspheric optics made by thin film epoxy replication, replication of transmissive optical surfaces, stability of lightweight replicated mirrors, replication of optical components, novel ultraviolet light-absorbing polymers for optical applications, improved acrylic resins for optical applications, novel acrylic resin for injection-molded precision lenses, and birefringence control in optical disk molding. Also addressed are: development of prototype plastic optics, molded acrylic retroreflector, injection molding of optical components, coating of plastics, problems and solutions for coating plastic optics, abrasion testing of coated plastic lenses, surface enhancement for optical plastics, survey of present lens-molding techniques, new directions in glass and plastic aspherics, characterization of molded glass and plastic aspheric lenses, and precision glass microlens array by a photothermal technique.

  1. Improved plastic molding technology for magneto-optical disk substrate

    NASA Astrophysics Data System (ADS)

    Galic, George J.

    1991-03-01

    A patented new injection-molding technology which already has been coninercially licensed nonexclusively to worldleading plastic magnetooptical (MO) mediamakers gives very high moldpacking pressures (needed for maximum microsurface replication) without high birefringence (minimized by reducing constrictiveness during fill) even with high viscosity plastics. I . " STATFMENT OF ThE PROBLIM" FOB ERASABLE OPTICALDI 5K MOLDINQ Al though gl ass and new cross 1 inkabl e p1 as t i cs are cont ending wi th polycarbonate and other injection moldable thermoplastics for this new market polycarbonate has prevailed as " first generation" erasable media substrate (although product life considerations may require added barrier coat to the MO coating stacks thereof). If performance of all these substrate contenders were equal the injection moldable thermoplastics will be preferred due to lowest cost and most automatable production If molded thermoplastics don''t ultimately win out a main reason will have been that these disk products require a long narrow mold cavity to be filled by the thermoplastic of choice then packed at double the pressures used for digital audio compact disks (CDs) in order to force the molten thermoplastic against the staner microsurface until detailed microreplication is assured yet only very low moldedin stresses can be tolerated (typically 1/2 to 1/5 those of audio CDs) 1. 1 Fillrelated Molding Problems M-O disks typically are 130am or 86nin in diameter and as molded thickness of a single

  2. Innovative molding technologies for the fabrication of components for microsystems

    NASA Astrophysics Data System (ADS)

    Piotter, Volker; Benzler, Tobias; Hanemann, Thomas; Woellmer, Heinz; Ruprecht, Robert; Hausselt, Juergen H.

    1999-03-01

    Economic success of microsystems technology requires a wide range of materials as well as the related manufacturing processes. A suitable technology for medium/large scale production is micro injection molding which actually allows the manufacturing of plastic microstructures with 20 microns minimum thickness, structural details of approximately 0.2 microns or maximum aspect ratios of more than 20. These microstructures are, for example, applied as components in micro optics, micro fluidics or minimally invasive surgery. This is demonstrated by microparts that are currently available or will be available soon. For higher economic efficiency and cost reduction, fully electrical injection modeling machines of higher accuracy have been applied. Also, micro insert injection molding reduces mounting costs. Manufacturing of metal or ceramic microparts by powder injection modeling allows large-scale production of complex shaped microstructures with a wide range of materials. Typical examples are sintered structured like stepped LIGA- gear wheels with minimal dimensions of 50 microns in different metal and ceramic materials. Micro Precision Casting originating from conventional investment casting is a suitable process for small/medium-scale production. Examples are microturbine housings made of precious metal alloys. An approach similar to rapid prototyping applies photocurable reactive resins. Photoinduced molding of low viscous resins under ambient conditions leads to significantly reduced cycle times. Additionally, rapid testing of new composite materials can be performed easily. Microcomponents molded from polymers and different composites like dyes with nonlinear optical properties and nanosized ceramic powders will be presented.

  3. Fabrication of Molded Magnetic Article

    NASA Technical Reports Server (NTRS)

    Bryant, Robert G. (Inventor); Namkung, Min (Inventor); Wincheski, Russell A. (Inventor); Fox, Robert L. (Inventor)

    2001-01-01

    A molded magnetic article and fabrication method are provided. Particles of ferromagnetic material embedded in a polymer binder are molded under heat and pressure into a geometric shape. Each particle is an oblate spheroid having a radius-to-thickness aspect ratio approximately in the range of 15-30. Each oblate spheroid has flattened poles that are substantially in perpendicular alignment to a direction of the molding pressure throughout the geometric shape.

  4. Method for molding ceramic powders

    DOEpatents

    Janney, M.A.

    1990-01-16

    A method for molding ceramic powders comprises forming a slurry mixture including ceramic powder, a dispersant for the metal-containing powder, and a monomer solution. The monomer solution includes at least one multifunctional monomer, a free-radical initiator, and an organic 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, where after the product may be sintered.

  5. Method for molding ceramic powders

    DOEpatents

    Janney, Mark A.

    1990-01-01

    A method for molding ceramic powders comprises forming a slurry mixture including ceramic powder, a dispersant for the metal-containing powder, and a monomer solution. The monomer solution includes at least one multifunctional monomer, a free-radical initiator, and an organic 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.

  6. 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.

  7. 8. VIEW OF A MOLD FOR PRECISION CASTING. THE MOLD ...

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

    8. VIEW OF A MOLD FOR PRECISION CASTING. THE MOLD WAS USED IN FOUNDRY OPERATIONS THAT CAST PLUTONIUM EITHER AS INGOTS SUITABLE FOR ROLLING AND FURTHER WROUGHT PROCESSING OR INTO SHAPES AMENABLE TO DIRECT MACHINING OPERATIONS. (5/6/59) - Rocky Flats Plant, Plutonium Fabrication, Central section of Plant, Golden, Jefferson County, CO

  8. MOLD SPECIFIC QUANTITATIVE PCR: THE EMERGING STANDARD IN MOLD ANALYSIS

    EPA Science Inventory

    Today I will talk about the use of quantitative or Real time PCR for the standardized identification and quantification of molds. There are probably at least 100,000 species of molds or fungi. But there are actually about 100 typically found indoors. Some pose a threat to human...

  9. MOLD SPECIFIC QUANTITATIVE PCR: THE EMERGING STANDARD IN MOLD ANALYSIS

    EPA Science Inventory

    Today I will talk about the use of quantitative or Real time PCR for the standardized identification and quantification of molds. There are probably at least 100,000 species of molds or fungi. But there are actually about 100 typically found indoors. Some pose a threat to human...

  10. In-mold sensor concept to calculate process-specific rheological properties

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    To gain extended knowledge on the flow behavior of polymer melts during filling phase of the injection molding process, an injection mold featuring complex sensor technology was developed. Three triple-combined FOS MTPS408 cavity sensors (FOS Messtechnik GmbH) are aligned along the flow path of a plate-shaped cavity. Each sensor features an infrared detector, a type K thermocouple, and a piezo-electric pressure detector. This configuration enables the local and transient recording of melt temperature, mold temperature and cavity pressure near gate, part center and end of part simultaneously. Averaged melt velocities are determined by evaluating the differing times of the rising edges of the infrared sensors. Local melt velocities and viscosities are calculated at each sensor position by evaluation of the gradients of temperature and pressure. Moreover, the used injection mold is equipped with RHCM technologies to additionally influence the mold surface temperature and hence the filling of the cavity. The specimens are plate-shaped parts having cut-outs and ribs similar to geometries found in numerous industrial applications such as cover panels. The application of this in-mold sensor concept provides novel possibilities for the systematic in-line analysis and evaluation of process-parameters in injection molding. Further studies will be carried out to connect the process-specific properties to the specimen morphology; aiming at controlling morphology by adjusting process parameters.

  11. Mold Materials For Permanent Molding of Aluminum Alloys

    SciTech Connect

    John F Wallace; David Schwam; Wen Hong dxs11@po.cwru.edu

    2001-09-14

    A test that involves immersion of the potential mod materials for permanent molds has been developed that provides a thermal cycle that is similar to the experienced during casting of aluminum in permanent molds. This test has been employed to determine the relative thermal fatigue resistance of several different types of mold materials. Four commercial mold coatings have been evaluated for their insulating ability, wear resistance and roughness. The results indicate that composition and structure of the mold materials have considerable effect on their thermal fatigue cracking behavior. Irons with a gray iron structure are the most prone to thermal fatigue cracking followed by compacted graphite irons with the least thermal fatigue cracking of the cast irons experienced by ductile iron. The composition of these various irons affects their behavior.

  12. Composite materials molding simulation for purpose of automotive industry

    NASA Astrophysics Data System (ADS)

    Grabowski, Ł.; Baier, A.; Majzner, M.; Sobek, M.

    2016-08-01

    Composite materials loom large increasingly important role in the overall industry. Composite material have a special role in the ever-evolving automotive industry. Every year the composite materials are used in a growing number of elements included in the cars construction. Development requires the search for ever new applications of composite materials in areas where previously were used only metal materials. Requirements for modern solutions, such as reducing the weight of vehicles, the required strength and vibration damping characteristics go hand in hand with the properties of modern composite materials. The designers faced the challenge of the use of modern composite materials in the construction of bodies of power steering systems in vehicles. The initial choice of method for producing composite bodies was the method of molding injection of composite material. Molding injection of polymeric materials is a widely known and used for many years, but the molding injection of composite materials is a relatively new issue, innovative, it is not very common and is characterized by different conditions, parameters and properties in relation to the classical method. Therefore, for the purpose of selecting the appropriate composite material for injection for the body of power steering system computer analysis using Siemens NX 10.0 environment, including Moldex 3d and EasyFill Advanced tool to simulate the injection of materials from the group of possible solutions were carried out. Analyses were carried out on a model of a modernized wheel case of power steering system. During analysis, input parameters, such as temperature, pressure injectors, temperature charts have been analysed. An important part of the analysis was to analyse the propagation of material inside the mold during injection, so that allowed to determine the shape formability and the existence of possible imperfections of shapes and locations air traps. A very important parameter received from

  13. Thermophilic molds: Biology and applications.

    PubMed

    Singh, Bijender; Poças-Fonseca, Marcio J; Johri, B N; Satyanarayana, Tulasi

    2016-11-01

    Thermophilic molds thrive in a variety of natural habitats including soils, composts, wood chip piles, nesting materials of birds and other animals, municipal refuse and others, and ubiquitous in their distribution. These molds grow in simple media containing carbon and nitrogen sources and mineral salts. Polyamines are synthesized in these molds and the composition of lipids varies considerably, predominantly containing palmitic, oleic and linoleic acids with low levels of lauric, palmiotoleic and stearic acids. Thermophilic molds are capable of efficiently degrading organic materials by secreting thermostable enzymes, which are useful in the bioremediation of industrial wastes and effluents that are rich in oil, heavy metals, anti-nutritional factors such as phytic acid and polysaccharides. Thermophilic molds synthesize several antimicrobial substances and biotechnologically useful miscellaneous enzymes. The analysis of genomes of thermophilic molds reveals high G:C contents, shorter introns and intergenic regions with lesser repetitive sequences, and further confirms their ability to degrade agro-residues efficiently. Genetic engineering has aided in ameliorating the characteristics of the enzymes of thermophilic molds. This review is aimed at focusing on the biology of thermophilic molds with emphasis on recent developments in the analysis of genomes, genetic engineering and potential applications.

  14. INDOOR MOLDS AND ALLERGIC POTENTIAL

    EPA Science Inventory

    Rationale: Damp/moldy environments have been associated with asthma exacerbation, but mold¿s role in allergic asthma induction is less clear. Recently, 5 molds were statistically associated with water-damaged asthmatic homes in the Cleveland area. The asthma exacerbation...

  15. Twistable mold for helicopter blades

    NASA Technical Reports Server (NTRS)

    Carter, E. S.; Kiely, E. F.

    1972-01-01

    Design is described of mold for fabrication of blades composed of sets of aerodynamic shells having same airfoil section characteristics but different distributions. Mold consists of opposing stacks of thin templates held together by long bolts. When bolts are loosened, templates can be set at different positions with respect to each other and then locked in place.

  16. INDOOR MOLDS AND ALLERGIC POTENTIAL

    EPA Science Inventory

    Rationale: Damp/moldy environments have been associated with asthma exacerbation, but mold¿s role in allergic asthma induction is less clear. Recently, 5 molds were statistically associated with water-damaged asthmatic homes in the Cleveland area. The asthma exacerbation...

  17. STANDARDIZED MOLD IDENTIFICATION AND ENUMERATION

    EPA Science Inventory

    There are probably at least 100,000 species of molds or fungi. But there are actually about 100 typically found indoors. Some pose a threat to humans and animals and others don't. We need to know what molds are present indoors and their concentrations. The older methods of cult...

  18. Diamond Grinding of Optical Surfaces on Aspheric Lens Molds

    NASA Astrophysics Data System (ADS)

    Chaloux, Leonard E.

    1986-10-01

    Through previous marketing surveys and discussions with many companies in 1984 and '85, it has become apparent that there is a growing need for a grinding machine capable of producing high quality, aspheric optical surfaces on various brittle materials that cannot be directly machined by single crystal diamond tools. Some of the materials of prime interest are ceramics and carbides, to be used as molds for plastic and glass lenses. Even though tool steel substrates with electroless nickel plating are being directly machined by single crystal diamond tools and used for injection molding of plastic lenses, the harder carbide and ceramic substrates have more desireable properties as molds for both plastic and glass lenses. Various applications of these lenses include use in: - Cameras and Photocopiers - Fiber Optic Connectors, and - Pick-up Heads for Compact Disc Players for both audio and read only memory (CD-ROM) applications.Upon closer evaluation of these applications, it is clear that a major portion of the lens mold market will be satisfied by the ability to grind aspheric surfaces up to a maximum diameter of 50mm. Also, to fulfill other requirements of these molds, a grinder must be capable of producing accurate alignment diameters and shoulders which are concentric and square to the optical axis of the aspheric surface. (see Figure 1.) This paper will discuss the design of a Grinding Attachment for a standard turning lathe, which is being used for fabrication of the lens molds previously described. It focuses on grinding of a silicon carbide mold. The following key areas will be discussed in detail: - Process Development a. grinding wheel selection b. wheel dressing c. wheel setting d. cutting parameters - Restrictions/Limitations - Accuracies Achieved a. form error b. surface finish

  19. 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.

  20. ILLUSTRATED HANDBOOK OF SOME COMMON MOLDS.

    ERIC Educational Resources Information Center

    CHANDLER, MARION N.

    THIS DOCUMENT IS A PICTURE GUIDE FOR THE IDENTIFICATION OF TEN COMMON MOLDS. IT IS DESIGNED FOR USE WITH THE ELEMENTARY SCIENCE STUDY UNIT "MICROGARDENING" AND IS SUGGESTED FOR UPPER ELEMENTARY GRADES. INCLUDED FOR EACH MOLD ARE COLOR PHOTOGRAPHS AND PHOTOMICROGRAPHS OF THE INTACT MOLD MASS AND OF THE MOLD'S SPORE PRODUCING STRUCTURES.…

  1. Mold Cleanup in Your Home

    EPA Pesticide Factsheets

    If you found mold in your household, you will want to clean it up. Some considerations on how you will clean it up depend on the size of the area, the contaminated materials, and any additional health concerns.

  2. White mold of Jerusalem artichoke

    USDA-ARS?s Scientific Manuscript database

    Jerusalem artichoke (Helianthus tuberosus) is a Native American food plant closely related to the common sunflower (Helianthus annuus). Tubers of Jerusalem artichoke are increasingly available in retail grocery outlets. White mold (Sclerotinia stem rot), caused by the fungus, Sclerotinia sclerotioru...

  3. Mold remediation in a hospital.

    PubMed

    Lee, Tang G

    2009-01-01

    As occupants in a hospital, patients are susceptible to air contaminants that can include biological agents dispersed throughout the premise. An exposed patient can become ill and require medical intervention. A consideration for patients is that they may have become environmentally sensitive and require placement in an environment that does not compromise their health. Unfortunately, the hospital environment often contains more biological substances than can be expected in an office or home environment. When a hospital also experiences water intrusion such as flooding or water leaks, resulting mold growth can seriously compromise the health of patients and others such as nursing staff and physicians (Burge, Indoor Air and Infectious Disease. Occupational Medicine: State of the Art Reviews, 1980; Lutz et al., Clinical Infectious Diseases 37: 786-793, 2003). Micro-organism growth can propagate if the water is not addressed quickly and effectively. Immunocompromised patients are particularly at risk when subjected to fungal infection such that the US Center for Disease Control issued guideline for building mold in health care facilities (Centers for Disease and Control [CDC], Centers for Disease and Control: Questions and Answers on Stachybotrys chartarum and Other Molds, 2000). This paper is based on mold remediation of one portion of a hospital unit due to water from construction activity and inadequate maintenance, resulting in mold growth. A large proportion of the hospital staff, primarily nurses in the dialysis unit, exhibited health symptoms consistent with mold exposure. Unfortunately, the hospital administrators did not consider the mold risk to be serious and refused an independent consultant retained by the nurse's union to examine the premise (Canadian Broadcasting Corporation [CBC], Nurses file complaints over mold at Foothills. Canadian Broadcasting Corporation, 2003). The nurse's union managed to have the premise examined by submitting a court order of

  4. Survey Of Present Lens Molding Techniques

    NASA Astrophysics Data System (ADS)

    Pollicove, Harvey M.

    1988-07-01

    This survey will provide an overview of glass molding technologies, with a concentration in the newest of the technologies - Precision Glass Molding (PGM). A brief description of various forms of glass molding, including an historical review of patents associated with precision molding, is given. A worldwide survey of known commercial availability and recent innovations in PGM at Kodak are presented as examples of the potential of the precision molding technology.

  5. Molded polymer solar water heater

    DOEpatents

    Bourne, Richard C.; Lee, Brian E.

    2004-11-09

    A solar water heater has a rotationally-molded water box and a glazing subassembly disposed over the water box that enhances solar gain and provides an insulating air space between the outside environment and the water box. When used with a pressurized water system, an internal heat exchanger is integrally molded within the water box. Mounting and connection hardware is included to provide a rapid and secure method of installation.

  6. 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.

  7. 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.

  8. Fabrication of aspherical polymer lenses using a tunable liquid-filled mold.

    PubMed

    Cho, Sung Hwan; Tsai, Frank S; Qiao, Wen; Kim, Nam-Hyong; Lo, Yu-Hwa

    2009-03-01

    We demonstrated a tunable molding process to fabricate aspherical polymer lenses that can reduce aberrations and the total length of an optical system. Radius of curvature and conic constant are shown to be the key parameters to characterize the lens profile. The good agreement between the measured profiles and the simulated profiles allows us to design and fabricate lenses of a wide range of user-specified properties. Compared to the conventional aspherical lens fabrication method using injection molding with a diamond-turned mold, the proposed method may yield savings in time and cost.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Contamination Barrier For Contour-Molding Material

    NASA Technical Reports Server (NTRS)

    Adams, James F.

    1988-01-01

    Release agent prevents molding compound from adhering to or contaminating surface. Cleaning agent, Turco 4215 NCLT, forms barrier preventing silicone molding compound from sticking to surface and leaving contaminating residue. Also see MFS-29243.

  15. National Allergy Bureau Pollen and Mold Report

    MedlinePlus

    ... Search Search AAAAI National Allergy Bureau Pollen and Mold Report Date: April 12, 2017 Location: San Antonio ( ... Service can automatically email you daily pollen and mold reports. Click here sign up! Return to Map ...

  16. Approach to control of fibre orientation on FRTP in injection moulding

    NASA Astrophysics Data System (ADS)

    Hirai, Tsuneo; Katayama, Tsutao; Hirai, Mitomo

    The present method for prediction and control of fiber orientation in the process of injection molding for reinforced thermoplastic-matrix components, where matrix flow patterns determine product mechanical properties, imposes a restriction to flow at the flow front throughout the fields of fiber orientation. This restriction has been found to create not only a stable flow front, but stable flow throughout the mold cavity. Attention is given to the instrumentation used in experimental visualizations of fiber orientation during injection molding.

  17. 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...

  18. 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...

  19. Blow molding of melt processible rubber

    SciTech Connect

    Abell, W.R.; Stuart, R.E.; Myrick, R.E.

    1991-07-01

    This article discusses the advantages of making hollow rubber parts by blow molding thermoplastic elastomers (TPEs) versus conventional rubber processing. It describes the various types of blow molding processes and it provides some insight into the rheological properties of melt processible rubber (MPR) and how MPR should be molded by each of these processes. A number of blow molded applications for MPR are also discussed.

  20. Making Internal Molds Of Long, Curved Tubes

    NASA Technical Reports Server (NTRS)

    Burley, Richard K.

    1989-01-01

    Mold material carried to internal weld joint and removed after impression taken. Remotely operated device makes impression mold of interior surface of tube at weld joint. Mold provides indication of extent of mismatch between members at joint. Maneuvered to weld inspected through curved tube 3 in. in diameter by 50 in. long. Readily adapted to making molds to measure depth of corrosion in boiler tubes or other pipes.

  1. Making Internal Molds Of Long, Curved Tubes

    NASA Technical Reports Server (NTRS)

    Burley, Richard K.

    1989-01-01

    Mold material carried to internal weld joint and removed after impression taken. Remotely operated device makes impression mold of interior surface of tube at weld joint. Mold provides indication of extent of mismatch between members at joint. Maneuvered to weld inspected through curved tube 3 in. in diameter by 50 in. long. Readily adapted to making molds to measure depth of corrosion in boiler tubes or other pipes.

  2. Mold inhibition on unseasoned southern pine

    Treesearch

    Carol A. Clausen; Vina W. Yang

    2003-01-01

    Concerns about indoor air quality due to mold growth have increased dramatically in the United States. In the absence of moisture management, fungicides need to be developed for indoor use to control mold establishment. An ideal fungicide for prevention of indoor mold growth on wood-based materials needs to specifically prevent spore germination and provide long-term...

  3. HOW to Recognize and Control Sooty Molds

    Treesearch

    Kenneth J. Jr. Kessler

    1992-01-01

    Sooty molds are dark fungi that grow on honeydew excreted by sucking insects or on exudates from leaves of certain plants. Typically, sooty mold growths are composed of fungal complexes made up of ascomycetes and fungi imperfecti. Some of the common genera of fungi found in sooty mold complexes are Cladosporium, Aureobasidium, Antennariella, Limacinula, Scorias, and...

  4. The Mold that Almost Ate the Principal

    ERIC Educational Resources Information Center

    Barry, Wayne; Bishop, Chuck; Byars, Jennifer

    2006-01-01

    New-building mold was a bane for many home construction companies and new homeowners during the 1990s. It was not unusual to read or watch the news and see the tragedy played out in one's local community. Untold, however, is the story of the toll new-building mold can take on school systems and their principals, especially as these mold problems…

  5. Snow Mold Investigations in Eastern Washington

    Treesearch

    T. H. Filer; A. G. Law

    1961-01-01

    "Snow mold of turf" in the Pacific Northwest must include both Fusarium Patch caused by Calonectria graminicola (Berk and Br.) (conidial stage Fusarium nivale (Fr. ) CES.), and Gray snow mold caused by Typhula itoana Imai, which occur together to give a disease complex. Snow mold of turf is the most...

  6. The Mold that Almost Ate the Principal

    ERIC Educational Resources Information Center

    Barry, Wayne; Bishop, Chuck; Byars, Jennifer

    2006-01-01

    New-building mold was a bane for many home construction companies and new homeowners during the 1990s. It was not unusual to read or watch the news and see the tragedy played out in one's local community. Untold, however, is the story of the toll new-building mold can take on school systems and their principals, especially as these mold problems…

  7. Attack of the Killer Mold Spores.

    ERIC Educational Resources Information Center

    Moore, Mary

    1999-01-01

    Describes experiences at the Arkansas State University at Jonesboro library when mold was discovered in a large portion of the monograph collection. Discusses causes of mold formation, equipment needed, news media coverage, staff involvement in the cleanup, and possible health hazards from mold. (LRW)

  8. ALLERGIC POTENTIAL OF INDOOR MOLDS

    EPA Science Inventory

    Many fungi have been associated with allergic lung disease, but few are well studied and even fewer allergens of fungal origin are well characterized. Exposure to damp moldy environments has been associated with the exacerbation of asthma, but the role of molds in the induction o...

  9. ALLERGIC POTENTIAL OF INDOOR MOLDS

    EPA Science Inventory

    Many fungi have been associated with allergic lung disease, but few are well studied and even fewer allergens of fungal origin are well characterized. Exposure to damp moldy environments has been associated with the exacerbation of asthma, but the role of molds in the induction o...

  10. Molded Concrete Center Mine Wall

    NASA Technical Reports Server (NTRS)

    Lewis, E. V.

    1987-01-01

    Proposed semiautomatic system forms concrete-foam wall along middle of coal-mine passage. Wall helps support roof and divides passage into two conduits needed for ventilation of coal face. Mobile mold and concrete-foam generator form sections of wall in place.

  11. Is Mold the New Asbestos?

    ERIC Educational Resources Information Center

    Colgan, Craig

    2003-01-01

    Mold and indoor air quality (IAQ) are matters of major concern to architects and their educational clients. The Environmental Protection Agency's Indoor Air Quality Tools for Schools program offers help to districts seeking to tackle IAQ issues. Strengthening community relations is one way to be ready in case of a bad environmental or IAQ report.…

  12. ANIMAL MODELS OF MOLD ALLERGY

    EPA Science Inventory

    The concept of molds as causative agents for allergy/asthma is not new. In fact many fungal genera have been associated with allergic lung disease, but only a few fungi are well studied and even fewer fungal allergens well characterized. The complexity and variety of fungal pro...

  13. Molded Concrete Center Mine Wall

    NASA Technical Reports Server (NTRS)

    Lewis, E. V.

    1987-01-01

    Proposed semiautomatic system forms concrete-foam wall along middle of coal-mine passage. Wall helps support roof and divides passage into two conduits needed for ventilation of coal face. Mobile mold and concrete-foam generator form sections of wall in place.

  14. Is Mold the New Asbestos?

    ERIC Educational Resources Information Center

    Colgan, Craig

    2003-01-01

    Mold and indoor air quality (IAQ) are matters of major concern to architects and their educational clients. The Environmental Protection Agency's Indoor Air Quality Tools for Schools program offers help to districts seeking to tackle IAQ issues. Strengthening community relations is one way to be ready in case of a bad environmental or IAQ report.…

  15. ANIMAL MODELS OF MOLD ALLERGY

    EPA Science Inventory

    The concept of molds as causative agents for allergy/asthma is not new. In fact many fungal genera have been associated with allergic lung disease, but only a few fungi are well studied and even fewer fungal allergens well characterized. The complexity and variety of fungal pro...

  16. Effect of fast mold surface temperature evolution on iPP part morphology gradients

    SciTech Connect

    Liparoti, Sara; Sorrentino, Andrea; Guzman, Gustavo; Cakmak, Mukerrem; Titomanlio, Giuseppe

    2016-03-09

    The control of mold surface temperature is an important factor that affects the sample surface morphology as well as the structural gradients (orientation crystal size, and type) as well as cooling stresses. The frozen layer thickness formed during the filling stage also has a very significant effect on the flow resistance and thus on the resulting pressure drop and flow length in thin wall parts. The possibility to have a hot mold during filling and a quick cooling soon afterward is a significant process enhancement particularly for specialized applications such as micro injection molding and for the reproduction of micro structured surfaces. Up to now, several methods (electromagnetic, infrared, hot vapor fleshing etc,) were tried to achieve fast temperature evolution of the mold. Unfortunately, all these methods require a complex balance between thermal and mechanical problems, equipment cost, energy consumption, safety, molding cycle time and part quality achievable. In this work, a thin electrical resistance was designed and used to generate a fast and confined temperature variation on mold surface (by joule effect). Since the whole temperature evolution can take place in a few seconds, one can couple the advantages of a high surface temperature during filling with the advantages of a low mold temperature, fast cooling and low heating dissipation. Some experiments were performed with a commercial iPP resin. The effects of the surface temperature and of the heating time (under constant electric power) on surface finishing and on the final morphology (thickness and structure of the different layers) are explored and discussed.

  17. Effect of fast mold surface temperature evolution on iPP part morphology gradients

    NASA Astrophysics Data System (ADS)

    Liparoti, Sara; Sorrentino, Andrea; Guzman, Gustavo; Cakmak, Mukerrem; Titomanlio, Giuseppe

    2016-03-01

    The control of mold surface temperature is an important factor that affects the sample surface morphology as well as the structural gradients (orientation crystal size, and type) as well as cooling stresses. The frozen layer thickness formed during the filling stage also has a very significant effect on the flow resistance and thus on the resulting pressure drop and flow length in thin wall parts. The possibility to have a hot mold during filling and a quick cooling soon afterward is a significant process enhancement particularly for specialized applications such as micro injection molding and for the reproduction of micro structured surfaces. Up to now, several methods (electromagnetic, infrared, hot vapor fleshing etc,) were tried to achieve fast temperature evolution of the mold. Unfortunately, all these methods require a complex balance between thermal and mechanical problems, equipment cost, energy consumption, safety, molding cycle time and part quality achievable. In this work, a thin electrical resistance was designed and used to generate a fast and confined temperature variation on mold surface (by joule effect). Since the whole temperature evolution can take place in a few seconds, one can couple the advantages of a high surface temperature during filling with the advantages of a low mold temperature, fast cooling and low heating dissipation. Some experiments were performed with a commercial iPP resin. The effects of the surface temperature and of the heating time (under constant electric power) on surface finishing and on the final morphology (thickness and structure of the different layers) are explored and discussed.

  18. 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.

  19. HIGH TEMPERATURE REFRACTORY COATING FOR GRAPHITE MOLDS

    DOEpatents

    Stoddard, S.D.

    1958-10-21

    An improved foundry mold coating for use with graphite molds used in the casting of uranium is presented. The refractory mold coating serves to keep the molten uranium from contact with graphite of the mold and thus prevents carbon pickup by the molten metal. The refractory coating is made by dry mixing certain specific amounts of aluminum oxide, bentonite, Tennessee ball clay, and a soluble silicate salt. Water is then added to the mixture and the suspension thus formed is applied by spraying onto the mold.

  20. Incipient flocculation molding: A new ceramic-forming technique

    NASA Astrophysics Data System (ADS)

    Arrasmith, Steven Reade

    Incipient Flocculation Molding (IFM) was conceived as a new near-net-shape forming technique for ceramic components. It was hypothesized that the development of a temperature-dependent deflocculant would result in a forming technique that is flexible, efficient, and capable of producing a superior microstructure with improved mechanical properties from highly reactive, submicron ceramic powders. IFM utilizes a concentrated, nonaqueous, sterically stabilized ceramic powder and/or colloidal suspension which is injected into a non-porous mold. The suspension is then flocculated by destabilizing the suspension by lowering the temperature. Flocculation is both rapid and reversible. Cooling to -20°C produces a green body with sufficient strength for removal from the mold. The solvent is removed from the green body by evaporation. The dried green body is subsequently sintered to form a dense ceramic monolith. This is the first ceramic forming method based upon the manipulation of a sterically-stabilized suspension. To demonstrate IFM, the process of grafting polyethylene glycol (PEG), with molecular weights from 600 to 8000, to alumina powders was investigated. The maximum grafted amounts were achieved by the technique of dispersing the alumina powders in molten polymer at 195°C. The ungrafted PEG was then removed by repeated centrifuging and redispersion in fresh distilled water. The rheological behavior of suspensions of the PEG-grafted powders in water, 2-propanol and 2-butanol were characterized. All of the aqueous suspensions were shear thinning. The PEG 4600-grafted alumina powder aqueous suspensions were the most fluid. Sample rods and bars were molded from 52 vol% PEG-grafted alumina suspensions in 2-butanol. The best results were obtained with a preheated aluminum mold lubricated with a fluorinated oil mold-release. The samples were dried, sintered, and their microstructure and density were compared with sintered samples dry pressed from the same alumina powder