• Title, Summary, Keyword: Injection Molding

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The Behavior of Shrinkage on PMMA in Injection Molding Compression Molding (사출압축성형시 PMMA 재료의 성형수축거동)

  • Choi, Y.S.;Han, S.R.;Jeong, Y.D.
    • Journal of the Korea Society For Power System Engineering
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    • v.9 no.4
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    • pp.83-89
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    • 2005
  • Molding shrinkage is one of the problems to be solved in conventional injection molding. Despite many trying-out has been to solve it, intrinsic cause of shrinkage such as orientation and thermal exchange between melt and mold has not been solved yet. For reducing shrinkage and residual stress on molding, injection compression molding process was invented. In this study, experiments about effects of injection compression molding's parameters on shrinkage of PMMA molding were conducted and compared with conventional injection molding's shrinkage. Before the injection compression molding experiment, molding shrinkage rate was predicted by analyzing pvT diagram and was compared with the results of experiment. The shrinkage rate of injection compression molding was lower than convention injection molding's one which was different from the predicted shrinkage. The reason was observed that the experimental mold was not a proper type for injection compression, flowing backward of melt into nozzle and unreasonable mechanism of injection molding machine.

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A Study on the Molding Characteristics of Injection Compression Molding Through Computer Simulation (컴퓨터 해석을 통한 사출압축성형의 성형특성에 관한 연구)

  • Chun, Y.H.;An, H.G.;Lyu, M.Y.
    • Elastomers and Composites
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    • v.47 no.4
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    • pp.341-346
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    • 2012
  • Injection molding is one of the widely used polymer processing operations. It is being used for not only conventional injection molding but gas injection molding, water injection molding, and injection compression molding. Injection compression molding involves injection and compression operation, and it gives uniform physical property and high dimensional quality of product. In this study, injection compression characteristics for various product shapes have been investigated by computer simulation. Product containing side wall showed not much effective in injection compression molding since wall thickness direction was perpendicular to the compression direction. Uniform and low shrinkage was observed in injection compression molding comparing conventional injection molding. Subsequently injection compression molding can be used for molding precise product. Optimal injection compression molding condition was obtained using design of experiment for plastic lens and the results were compared with conventional injection molding.

The Behavior of Shrinkage on PMMA in Injection Compression Molding (사출압축성형시 PMMA 재료의 성형수축거동)

  • Choi Y.S.;Kang C.M.;Jeong Y.D.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.589-592
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    • 2005
  • Molding shrinkage s variation is one of the problems to be solved in conventional injection molding. Despite many trying-out has been to solve these, intrinsic causes of shrinkage such as orientation and thermal exchange between melt and mold has yet not solved. For reducing shrinkage and residual stress on molding, injection compression molding process was invented. In this study, experiments about effect of injection compression molding's parameters on shrinkage of molding were conducted with PMMA and compared with conventional injection molding's shrinkage. Before the injection compression molding experiment, molding shrinkage rate was predicted by analyzing pvT graph and was compared with the results of experiment. The shrinkage rate of injection compression molding was lower than convention injection molding' one but was different from the predicted shrinkage. The reason was observed that experiment mold as not positive type, flowing backward of melt into nozzle and unreasonable mechanism of injection molding machine.

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Analysis of the Physical Quantity Variation in the Cavity and the Quality of the Molded Product According to the Injection Speed in Injection Molding

  • Kwon, Soon Yong;Cho, Jung Hwan;Roh, Hyung Jin;Cho, Sung Hwan;Lee, Yoo Jin;Lyu, Min-Young
    • Elastomers and Composites
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    • v.52 no.4
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    • pp.317-325
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    • 2017
  • Molding conditions can be described as factors that determine the quality of a product obtained from injection molding. Many studies have been performed on the injection molding pressure, injection temperature, packing pressure and other molding conditions related to part quality. However, the most accessible factor among the adjustable molding conditions during actual injection is the injection speed. In this study, we simulated the variation of the physical quantity according to injection speed and performed experiments to understand the effect of injection speed on the actual product. A CAE analysis program (Moldflow) was used to simulate and analyze the results using PC and PBT for two models. In order to compare these results with the experimental results, an actual injection molding was performed for each injection speed, and the correlation between simulation and injection molding, especially for the shrinkage of the molded article, was discussed.

Injection Molding Analysis of Battery case considering the Insert Deformation (인서트 변형을 고려한 배터리 케이스 사출 성형 해석)

  • Ahn, Dong-Gyu;Kim, Dea-Won
    • Proceedings of the KSME Conference
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    • pp.1107-1112
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    • 2008
  • The objective of this paper is to investigate into the influence of the injection conditions on the insert deformation and the wall thickness of the injection part using the three-dimensional injection molding analysis. Full three-dimensional insert model was added to the injection molding analysis model to consider the effects of insert deformation during the injection molding process. In order to obtain the optimum injection molding condition with a minimum insert deformation, degree of experiments were utilized. From the results of the analyses, it was shown that the optimum injection condition is injection time of 1.6 sec, injection pressure of 30 MPa and packing time of 15 sec. In addition it was shown that the wall thickness is approached to target thickness when the core deformation is considered in the injection molding analysis.

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Prediction of Flash Generation in Two-Color Injection Molding using The Rapid Heat Cycle Molding Technology (금형 급속 가열-냉각이 적용된 이색사출성형의 플래쉬 발생 예측)

  • Park, H.P.;Cha, B.S.;Rhee, B.O.
    • Transactions of Materials Processing
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    • v.19 no.3
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    • pp.145-151
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    • 2010
  • In case of thin-wall two-color injection molding, flashing often occurs when molten polymer flows into small gap at the parting line in mold with high pressure or under the unbalanced clamping force condition. In this study, flashing was examined in the production of thin-wall notebook case with large area when the rapid heat cycle molding (RHCM) technology was applied to the two-color injection molding. The effects of the RHCM technology on the part properties and weld-lines were compared with conventional injection molding. The flashing caused by the clamping device of the two-color injection molding machine was examined and compared by experiments and CAE analyses.

A Study of Gas-Assisted Injection Molding of 17" Flat Monitor Front Cover (17" 평면 모니터 Front Cover의 가스사출성형에 관한 연구)

  • Kim, Hong-Seok;Son, Jung-Sik;Seo, Tae-Soo
    • Proceedings of the KSME Conference
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    • pp.766-771
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    • 2001
  • Gas-assisted injection molding is an innovative low-pressure injection molding technique that can provide numerous benefits such as reduced part warpage, excellent surface quality without sink marks, low injection pressure, and greater design flexibility. However, the adoption of gas-assisted injection molding may cause unexpected defects if the gas channel design is not conducted properly. The objective of this paper is to broaden the understanding of gas-assisted injection molding by summarizing the design procedures and experimental results of the gas-assisted injection molding of a 17" flat monitor front cover. The gas channels were designed by using Moldflow(MF/GAS) simulations and a 450 ton injection molding machine with a 5 stage pressure control gas kit was used in the experiments.

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The Effects of Injection Molding Conditions on Uniformity and Brightness of Light Guide Plate (도광판의 균일도 및 휘도에 사출성형조건이 미치는 영향)

  • Lee Sung-Hee;Kim S.W.;Lee H.S.;Kim J.D.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.1609-1612
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    • 2005
  • The effects of injection molding conditions on the uniformity and brightness of light guide plate(LGP) with micro-patterns were investigated in the present study. An injection molding system for stampers with mirco-pattern was designed and manufactured to perform experiment. Variations of injection molding speed, mold and melt temperature for LGP were considered in this work. Also, injection molding characteristics of LGP were investigated by numerical analysis using plastic injection molding commercial code. It was shown that injection molding conditions such as injection speed, melt temperature and mold temperature can have an effect on the uniformity and brightness of light guide plate.

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The Effect of Impacted Fracture in Glass Fiber Orientation with Injection Molding & Structural Coupled Analysis (사출-구조 연성해석을 통한 Glass Fiber 배향성이 충격 파괴에 미치는 영향)

  • Kim, Woong;Kim, JongRyang
    • Transactions of the Korean Society of Automotive Engineers
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    • v.25 no.1
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    • pp.35-41
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    • 2017
  • The use of engineering plastics in automotive components is increasing with the trend towards improving the car strength and reducing weight. Among the different choices of materials, engineering plastic emerged as the necessary material for achieving lower costs, reduced weight and improved production efficiency. To produce the automotive parts, it is important to predict defect and validation of injection molding prior to design. Injection molding analysis and structural analysis are widely applied as a part of the design process when developing automotive parts. Injection molding analysis, in particular, involves a highly complicated mechanism that requires deep knowledge of polymer properties as well as an analytic approach different from that used for a general isotropic material when the molded material is used as a structural material. This is because the parts made of polymer have pre-stress factors such as intrinsic deformation and residual stress. The most important factors for injection molded plastic products are injection molding condition and cavity design, taking into account ease of molding, mass production and application. Despite optimal injection molding conditions and cavity design, however, glass fiber orientation is critically linked to strength reduction. The application of injection molding and structural coupled analysis provides a low-cost solution for product molding and structural validation, all prior to the actual molding. The purpose of this study involves the validation, pre-study, and solution of defect in injection-molded polymer automotive parts using the simulation software for injection molding and structural coupled analysis. Finally, this thesis provides validation of an injection molding and structural coupled analytic mechanism that can demonstrate the effect of glass fiber orientation on mechanical strength. Design improvement ideas for the injection molded product of PPS (Poly Phenylene Sulfide)+40% glass fiber are also suggested.

A Study on the Molding Technology for the Preform of Blow Molding Through Compression Molding (압축성형을 통한 블로우 성형품용 프리폼 성형기술 연구)

  • Choi, S.H.;Min, H.K.;Lyu, M.Y.
    • Transactions of Materials Processing
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    • v.16 no.1
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    • pp.3-8
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    • 2007
  • Novel compression molding system for preform has been developed in this study. The preforms for injection blow molding and injection stretch blow molding are being manufactured by injection molding. However it contains gate mark that affects the bottom crack in the PET bottle. The compression molded preform does not contain gate mark, thus the appearance quality of bottle has been increased and the residual stress near gate(bottom of the bottle) has been reduced. The thickness distributions, haze, and transmittance are well accepted for the preform. Also, flow characteristics of the resin between a core and cavity could be analyzed through computer simulation.