• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.5
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• pp.575-582
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• 2010

In recent years, several rapid-mold-heating techniques that can be used for the injection molding of thin-walled parts or micro/nano structures have been developed. High-frequency induction heating, which involves heating by electromagnetic induction, is an efficient method for the rapid heating of mold surfaces. The present study proposes an integrated numerical model of the high-frequency induction heating process and the resulting injection molding process. To take into account the effects of thermal boundary conditions in induction heating, we carry out a fully integrated numerical analysis that combines electromagnetic field calculation, heat transfer analysis, and injection molding simulation. The proposed integrated simulation is extended to the injection molding of a thin-wall part, and the simulation results are compared with the experimental findings. The validity of the proposed simulation is discussed according to the ways of the boundary condition imposition.

• Elastomers and Composites
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• v.38 no.4
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• pp.295-302
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• 2003

The amount of shrinkage of injection molded parts is different from operational conditions of injection molding such as injection temperature, injection pressure and mold temperature, and mold design such as gate size. It also varies depending on the presence of crystalline structure in resins. In this study, part shrinkage was investigated for various operational conditions and resins. Poly(butylene terephthalate) (PBT) for crystalline polymer, and polycarbonate (PC) and poly(methyl methacrylate) (PMMA) for amorphous polymers were used. Crystall me polymer showed higher part shrinkage by about three times than that of amorphous polymers. Part shrinkage increased as melt and molt temperatures increased, and injection pressure decreased. Part shrinkage decreased as gate size increased since the pressure delivery is mush easier for larger gate sizes. Part shrinkage at the position close to the gate was larger than that or the position far from gate. This phenomenon might be occur by difference of residual stress.

• Polymer(Korea)
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• v.38 no.6
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• pp.708-713
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• 2014

Most plastics products are being produced by injection molding process. However, mold shrinkage is inevitable in injection molding process and it deteriorates dimensional quality through deflections and warpages. Mold shrinkage depends upon the material property of resin as well as injection molding condition. In this study, material property of resin has been predicted for glass fiber reinforced polycarbonate to control the warpage, and computer simulation of injection molding has been performed using predicted property. It was observed that the deflection of part decreased by the glass fiber reinforced resin. In order to verify the validity of this method and confidence of results, experiments of injection molding were performed. The results of experiments and computer simulations showed good agreement in their tendency of deflections. Consequently, it was concluded that the method of designing the material property of resin conducted in this study can be utilized to control the dimensional accuracy of injection molded products.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.04a
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• pp.70-75
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• 2004

In this study, the pattern of lens aberration was studied at different injection molding conditions such as injection speed, holding pressure, holding pressure time, mold temperature and cylinder temperature and, then, the results were analyzed with a laser interferometer. It was demonstrated that optimal condition of lens aberration could be achieved by adjustment of injection molding conditions.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.115-115
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• 2004

최근에는 자동차용 범퍼(Bumper), 인판넬(In-panel), 도어판넬(Door panel), 도어가니쉬(Door Garnish) 등과 같은 대형 사출성형품을 성형하기 위한 금형설계에 핫 러너 시스템(Hot Runner System)에 밸브 게이트(Valve Gate)를 채용한 밸브 게이트 시스템을 많이 사용하고 있다 이 시스템을 사용함으로서 성형 싸이클타임의 단축, 수지 스크랩의 감소 등의 말은 장점이 있으나, 실제 성형작업 적용 시 밸브 게이트의 작동순서 및 개폐시간의 제어 등에 정확한 표준이 없어 시험 사출시 최적 성형조건의 셋팅이 많은 시간을 소모하고 있는 문제점이 있다.(중략)

• Polymer(Korea)
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• v.38 no.2
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• pp.193-198
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• 2014

Lens and DVD require high quality of optical property. Conventional injection molded products contain high residual stress and this invokes birefringence since high cavity pressure and high temperature variation are involved in a molding process. Thus these products are often molded by injection compression molding in order to minimize the residual stress through reducing cavity pressure and uniform cavity pressure. In this study, molding parameters affecting molding quality such as property uniformity in injection compression molding were investigated through experiment. Molding quality deviations among the cavities in multi-cavity mold were also studied. Transparent resins, PC and PS were used in this study. Compression gap, compression speed, compression force, and compression delay time for processing variables in injection compression molding were applied in experiment. Compression force, compression delay time, and compression gap significantly affected the optical property of product. The degree of influence of process variable on the product quality was different in different resins. This implies that the optimal operational conditions in injection compression molding existed for each resin according to flow property.

• Journal of the KSME
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• v.51 no.4
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• pp.32-36
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• 2011

친환경적 기술 개발은 시대적인 요청 사항으로 매우 중요한 의미를 가진다. 이 글에서는 국내 사출성형 관련 산업이 선진국형 산업으로 도약하기 위해 충족해야 하는 기술적인 요구조건뿐만 아니라 친환경적 요구조건에 대해 정의와 평가 범위에 대해 살펴보고 이와 관련된 대표적인 신기술들의 목적과 특징을 간략하게 소개한다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.10
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• pp.42-47
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• 2017

In this study,we conducted an injection molding analysis of metal powder materials for the development of flanges, which are necessary adapters for optical communication. The metal powder injection molding process is a technique for producing an injection molded article having a complicated shape by mixing ceramic or stainless powder and binders. It is used to produce products which require complex processing technology or for which the productivity is low. The purpose of this study is to minimize the manufacturing processing of products which are manufactured through existing mechanical processing procedures. For the injection molding analysis, we mixed stainless STS316 metal powder with binders at a ratio of 6 to 4 to make molding materials consisting of granular pellets. Then, three-dimensional modeling and meshing were carried out to obtain the optimal injection molding analysis conditions(molding temperature, melting temperature, injection time, injection temperature, injection pressure, packing time and cooling time). As a result of the analysis, it was discovered that the inlet became available 13.29 seconds after the first injection. Also, as the flowing and packing in the melt through the sprue, runner and gate were stable, it is expected that good molds can be manufactured.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.7 no.3
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• pp.25-29
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• 2008

In this paper, we design internal space in plunger-type low pressure vacuum injection molding machine from numerical study. And we study characteristic of viscoelastic flow for searching injection molding condition. Then the flow analysis was performed using the CAE S/W. The result shows optimal value of nozzle and hole in injection chamber. And we investigated qualitatively relationship between injection pressure and injection mass flow with variable shear rate

• Proceedings of the KAIS Fall Conference
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• 2011.05b
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• pp.533-536
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• 2011

기어는 중요한 핵심 기계요소 중 하나로서 기계적 물성이 강화된 엔지니어링 플라스틱의 개발과 제품의 성능 향상 및 소형화, 경량화, 저소음화 등의 소비자 요구를 만족시키기 위한 노력에 편승하여 정밀도가 높은 플라스틱 기어에 대한 생산 요구가 증대되고 있는 실정이다. 본 논문에서는 시력 측정 장치인 자동굴절검사기용 디스크 기어에 대하여 변형을 최소화하기 위한 성형조건 최적화를 수행하였다. 사출 공정의 주요 공정변수를 사출온도, 충진시간과 보압압력, 금형온도로 정하고 다구치 방법에 의해 성형 해석으로 예측된 변형량을 분석한 결과 사출온도와 보압압력이 원판형 기어의 Z방향 변형에 가장 큰 영향을 미치는 것을 알 수 있었다.