• Design & Manufacturing
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• 제14권4호
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• pp.11-16
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• 2020

In this study, forming of carbon composite parts was performed using an injection/compression molding process. An impregnation of matrix is determined by ability of wet and flow rate between the matrix and reinforcement. The flow rate of matrix passing through the reinforcements is a function of permeability of reinforcement, a viscosity of matrix and pressure gradient on molding, and the viscosity of the matrix depends on the mold temperature, molding pressure and shear strain of matrix. Therefore, compression molding experiment was conducted using a heating mold in order to confirm the possibility of matrix impregnation. The impregnation of the matrix through the porosities between the woven yarns was confirmed by the cross-sectional SEM image of compression molded parts. An injection molding process was also performed at a short cycle time, high molding pressure and low mold temperature than those of compression experiment conditions. Deterioration of impregnation on the surface of molded parts were caused by these injection conditions and it could be the reason of decreasing the maximum tensile strength. In order to improve impregnation of matrix on the surface, injection/compression molding and insert-over molding were applied. As a result of applying injection/compression molding and insert-over molding, it was shown that the improvement of impregnation on the surface and the maximum tensile strength was increased about 2.8 times than the virgin matrix.

• 대한기계학회논문집A
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• 제35권12호
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• pp.1635-1640
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• 2011

본 논문의 목적은 수치해석을 통한 자동차 와이퍼 소켓 부품 제작용 오버몰딩 금형의 냉각 시스템 설계이다. 초기 금형설계에 대한 수치해석을 수행하여 제품내 높은 온도 분포를 나타내는 열집중 영역을 도출하였다. 열집중 영역의 냉각특성 개선을 위하여 직선형 냉각수로와 체적 열 흡수부의 2 가지 냉각시스템을 고려하였다. 직선형 냉각수로의 설계를 도출하기 위하여 냉각수로의 직경과 위치가 냉각 특성과 제품 품질에 미치는 영향을 정량적으로 분석하였다. 또한 체적 열 흡수부 설계가 제품 냉각 특성과 변형에 미치는 영향을 고찰하였다. 최종적으로 체적 열 흡수부가 추가된 다중 슬라이스 오버몰딩 금형이 냉각 특성과 제품품질을 동시에 향상시킬 수 있음을 알 수 있었다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.295-298
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• 2004

Automobile door-handle is assembled with three parts that are base, skin and cover. Over-molding processing makes assembly of the base and skin. The skin part that was made by PVC polymer has various thickness. Plastic injection molding simulation of part including significant changed thickness as skin is an inaccuracy comparing with real injection molding. To solve this problem, two commercial flow prediction software that are Moldflow MPI and MAPS 3D were used in this study. Simulations were conducted for three types mesh. Taguchi method was applied for simulation experiments. It will be need to compare with simulation results and real over-molding behavior in the near future.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 The Korea-Japan Plastics Processing Joint Seminar
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• pp.27-32
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• 2003

The wavelike flow mark phenomenon is one of the surface defects that can arise during the injection stage of the injection molding process. We have performed a numerical analysis using a finite element method for the injection molding to verify the validity of 'Go-over' hypothesis. Also, we have compared the results of numerical analysis with available experimental data. Numerical analysis results of the flow marks are qualitatively in good agreement with experimental data of reference, but are quantitatively deviated from experimental data in a consistent manner. A parametric study has been performed to examine the correlative effects of various injection molding processing parameters and material properties on the flow mark size.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 춘계학술대회논문집
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• pp.474-480
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• 2003

The wavelike flow mark phenomenon is one of the surface defects that can arise during the injection stage of the injection molding process. We have performed a numerical analysis using a finite element method for the injection molding to verify the validity of “Go-over” hypothesis. Also, we have compared the results of numerical analysis with available experimental data. Numerical analysis results of the flow marks are qualitatively in good agreement with experimental data of reference, but are quantitatively deviated from experimental data in a consistent manner. A parametric study has been performed to examine the correlative effects of various injection molding processing parameters and material properties on the flow mark size.

• Design & Manufacturing
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• 제2권5호
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• pp.30-33
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• 2008

Injection Molding is the most effective process for mass production of plastic parts. The injection molding process is composed with several steps such as Filling, Packing, Holding, Cooling, Ejecting. Among them, filling and packing process should be considered carefully to improve accuracy of dimension, surface quality of plastic parts. Usually the quality above-mentioned is managed with weight of part after molding on the field. In this paper, a series of experiment for molding automotive front bumper was conducted with cavitity temperature sensor to optimize switch-over time(V-P switching), hot runner vale gate sequence time during filling and packing step for the purpose of uniform quality, weight at every molding. As a result, it was found that it is effective method to use temperature sensor in injection molding for quality control of plastic molding.

• 소성∙가공
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• 제22권1호
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• pp.48-53
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• 2013

As the adoption of injection molding technology increases, injected-molded optical products require higher dimensional accuracy and optical stability than ever before. In the present study, four kinds of molding methods, i.e., conventional injection molding (CIM), injection/compression molding (ICM), rapid heat and cooling the mold(RHCM) and rapid injection/compression molding (RICM) were selected in order to investigate the optical anisotropy of a 7 inch Light Guide Plate(LGP) by examining the gap-wise distribution of birefringence and the extinction angle. The results indicate that the compression process can decrease flow-induced birefringence over the whole region and that rapid heating can decrease the birefringence level better than conventional molding. In addition, for the combination of compression and rapid heating a reversal flow was detected from the distribution of the extinction angle near the gate.

• 한국기계가공학회지
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• 제17권1호
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• pp.95-100
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• 2018

This study has focused on the weld-line and birefringence reduction of a plastic optic lens using over and CAE analysis in injection compression molding. A concave lens, which has a thin thickness in the center and a large difference in thickness between the center and the periphery, often causes weld-line defects during injection molding. CAE analysis has been applied to optimize the overflow design in order to reduce the weld-line defects and the polarization defects. To reduce the weld line and birefringence defects, overflow design and application using CAE analysis show that the measured birefringence values of the specimens before the overflow application were 46.8nm and 36.9nm, and the values after the over-flow application were 13.6nm and 14.0nm. From the experimental results, it is confirmed that birefringence is greatly improved when overflow is applied.

• 한국정밀공학회지
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• 제29권1호
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• pp.13-18
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• 2012

In this study, silicone injection molding technology with curved thermoplastic insert was developed to produce super-hydrophobic surface. Thermoplastic insert part and injection mold design of base plastic cover were performed to produce cost effective hydrophobic surface part. An optimization process of part thickness for thermoplastic insert part was performed with transient thermal analysis under silicone over-molding process condition. Structural thermal analysis of silicone injection mold was also performed to obtain uniform temperature condition on the surface of micro-patterned mold core. Super-hydrophobic surface for the silicone injection molded part with thermoplastic insert could be verified from the measurement of contact angle. It was shown that the averaged contact angle was over $140^{\circ}$.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 추계학술대회 논문집
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• pp.99-102
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• 2009

The recent LCD TV market has made efforts to produce thinner, brighter, and clearer products, and experienced the rapid light source replacement from a line source of light CCFL to a point source of light LED. In particular, LGP(Light Guiding Panel) among key parts composing BLU(Back Light Unit) has limits of the injection molding technology as well as the mold design, its processing and manufacturing technology so that it is hard to produce large LGP over 40 inch. To produce large light-guide panels over 40 inch under the injection molding process, a mold 3D model was developed in the design process before manufacturing a mold and structure unification was processed through CAE analysis. As a result, it was possible to construct the mold design process, and it is expected to manufacture the optimized mold by applying the mold design and manufacturing process of large-scale rapid injection-compression molding that will be produced in the future.