• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 추계학술대회 논문집
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• pp.444-447
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• 2008

Recently, the need of thin-walled injection molding and enhancement of its productivity is greatly increased. In this study, we designed and manufactured a injection molding system, which can mold a part with the thickness of $500{\mu}m$ and 8 cavity. And processing technique for the multi-cavity injection molding system, which is capable of mass productivity on the plastic parts, was considered. The problems of unbalance/imbalance on the molding process for the multi-cavity mold were predicted by numerical analysis using plastic injection molding commercial code. In addition, controllable system of melt front filling was introduced for a balanced filling using the mold temperature sensor on injection mold. It was shown that balanced filling with the suggested injection molding system was possible for $500{\mu}m$ plastic parts with 8 cavity layout.

• Design & Manufacturing
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• 제7권1호
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• pp.1-6
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• 2013

The injection molding process is a predominant method for producing plastic parts. In order to maximize productivity and molding quality in a injection mold, it is important that each cavity in a multi-cavity injection mold is identical. This requires that cavity dimensions should be identical and delivery system of melt to each cavity have to be the same. Despite the geometrically balanced layout in multi-cavity injection mold more than 4 cavities, it has been observed that the filling in each cavity results in imbalances. Most of cases, this phenomenon of filling imbalances have a bad effect on dimension accuracy, warpage, molding appearance and strength of molding parts. In this study, experiment were conducted to investigate the effect of filling imbalances on the molding quality(surface gloss, shrinkage, tensile strength) in the multy-cavity injection mold.

• 한국금형공학회:학술대회논문집
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• 한국금형공학회 2008년도 하계 학술대회
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• pp.89-94
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• 2008

The injection molding process is a predominant method for producing plastic parts. In order to maximize productivity and molding quality in a injection mold, it is important that each cavity in a multi-cavity injection mold is identical. This requires that cavity dimensions should be identical and delivery system of melt to each cavity have to be the same. Despite the geometrically balanced layout in multi-cavity injection mold more than 4 cavities, it has been observed that the filling in each cavity results in imbalances. Most of cases, this phenomenon of filling imbalances have a bad effect on dimension accuracy, warpage, molding appearance and strength of molding parts. In this study, experiment were conducted to investigate the effect of filling imbalances on the molding quality(surface gloss, shrinkage, tensile strength) in the multy-cavity injection mold.

• 폴리머
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• 제38권2호
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• pp.144-149
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• 2014

일반사출성형은 공정 중 보압단계에서 캐비티에 높은 압력이 작용하여 성형품에 큰 잔류응력이 남게 된다. 또한 캐비티 내 위치 별로 압력분포가 달라 균일한 물성의 제품을 얻는데 한계가 있다. 다수 개 빼기 일반사출성형에서는 캐비티간 충전 불균형이 일어나 캐비티간 품질의 편차를 일으킨다. 이와 같은 한계를 극복하기 위해 사출압축성형 공정을 사용하는 경우가 많다. 본 연구에서는 다수 개 캐비티를 갖는 금형을 이용하여 일반사출성형과 사출압축성형을 비교 분석하였다. 실험과 해석을 통하여 연구를 수행하였으며 투명한 수지인 PC와 PS를 이용하여 시편에 나타나는 복굴절을 관찰하여 일반사출성형과 사출압축성형에서 나타나는 성형특성을 비교하였다. 연구결과, 사출 압축성형으로 제작된 시편에서 캐비티 내의 압력이 균일하여 복굴절과 성형수축률이 낮고 균일하게 나타났다. 그리고 일반사출성형에서 나타나는 캐비티간 충전 불균형에 의한 캐비티간 물성의 편차가 사출압축성형에서는 크게 줄어들었다. 본 연구를 통하여 사출압축성형은 다수 개 빼기 사출성형에서 캐비티 내 균일한 물성확보뿐만 아니라 캐비티간 품질 불균형을 해소하는데 유용함을 확인할 수 있었다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 추계학술대회 논문집
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• pp.266-270
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• 2007

Small injection molded articles such as lens and mobile product's parts are usually molded in multi-cavity mold. The problems occurred in multi-cavity molding are flow imbalance among the cavities. The flow imbalance affects on the dimensions and physical properties of molded articles. First of all, the origin of flow imbalance is geometrical imbalance of delivery system. However, even the geometry of delivery system is balanced well the cavity imbalance is being developed. This comes from the unsuitable operational conditions of injection molding. Among the operational conditions, injection speed is the most significant process variable affecting the filling imbalances in multi-cavity injection molding. In this study, experimental study of flow imbalance has been conducted for various injection speeds and materials. Also, the filling Imbalances were compared with CAE results. The dimensions and physical state of multi-cavity molded parts were examined. The results showed that the filling imbalances vary according to the injection speed and flow property of resins. Subsequently, the imbalanced filling and pressure distribution in the multi-cavity affect on the dimensions and physical states of molded parts.

• Design & Manufacturing
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• 제6권2호
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• pp.74-78
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• 2012

A multi-cavity injection mold system of protein chip for point-of-care with cavity temperature and pressure sensors was proposed in this work. In advance of manufacturing for the multi-cavity injection mold system, a single cavity injection mold system to mold protein chip was considered. Injection molding analysis for the presented system was performed to optimize the process of the molding and suggest guides to design. On the basis of the results for the single cavity system, a multi-cavity injection mold system for protein chip was analyzed, designed and manufactured with cavity temperature and pressure sensors. Results of balanced filling for protein chip models were obtained from the presented mold system.

• 소성∙가공
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• 제18권2호
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• pp.122-127
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• 2009

The injection mold with multi-cavity is essential for mass production of plastic products. Multi-cavity molds are designed to geometrically balanced runner system to uniformly fill to each cavity. However, despite geometrical balanced runner system, filling imbalances between cavity to cavity have always been observed in injection molding. To solve these problems, many studies such as Melt Flipper, RC Pin, and others have been presented. The results of these studies have been an effect on filling balances in multi-cavity molds. But, those have had a limitation that additional insert parts must have existed in the mold. In this study, a new runner system is suggested for filling balance between cavity to cavity using "Melt-Buffer" with simple change of runner shape. A series of simulation to confirm feasibility of Melt-Buffer's effects was conducted using injection molding CAE program. Also, a series of injection molding experiment was conducted using plastic materials such as ABS and PP. As results of this study, feasibilities of filling balances by Melt-Buffer were confirmed.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 춘계학술대회 논문집
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• pp.39-42
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• 2005

For mass production, usually injection mold has multi-cavity which is filled through geometrical balanced runner system. Despite geometrical balanced runner system, filling imbalances between cavity to cavity have always been observed. These filling imbalances are one of the most significant factors to affect quality of plastic parts when molding plastic parts in multi-cavity injection mold. Filling imbalances are results from non-symmetrical shear rate distribution within melt as it flows through the runner system. It has been possible to decrease filling imbalance by optimizing processing conditions, but it has not completely eliminated this phenomenon during injection molding processing. This paper presents a solution of these filling imbalances through using 'runner core pin'. The runner core pin which is developed in this study creates a symmetrical shear distribution within runner. As a result of using runner core pin, a remarkable improvement in reducing filling imbalance was confirmed.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 금형가공,미세가공,플라스틱가공 공동 심포지엄
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• pp.13-16
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• 2005

For mass production, usually injection mold has multi-cavity which is filled through geometrical balanced runner system. Despite geometrical balanced runner system, filling imbalances between cavity to cavity have always been observed. These filing imbalances are one of the most significant factors to affect quality of plastic parts when molding plastic parts in multi-cavity injection mold. Filling imbalances are results from non-symmetrical shear rate distribution within melt as it flows through the runner system. It has been possible to decrease filling imbalance by optimizing processing conditions, but it has not completely eliminated this phenomenon during injection molding processing. This paper presents a solution of these filling imbalances through using 'runner core pin'. The runner core pin which is developed in this study creates a symmetrical shear distribution within runner. As a result of using runner core pin, a remarkable improvement in reducing filling imbalance was confirmed.

• 폴리머
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• 제33권6호
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• pp.561-568
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• 2009

소형 플라스틱 부품들은 대부분 다수 캐비티 빼기 사출금형에서 성형된다. 이러한 다수 빼기 캐비티 금형에서의 사출성형은 캐비티간의 흐름 균형이 중요하다. 캐비티간 흐름의 불균형은 성형품의 캐비티간 물성 및 품질의 편차를 초래한다. 캐비티간의 흐름균형은 런너와 게이트에서의 흐름균형을 통하여 이루어지게 되는데 런너와 게이트에서 기하학적인 균형을 이루어도 열적 불균형으로 캐비티간 흐름의 불균형을 초래한다. 본 연구에서는 캐비티간 흐름의 균형을 위해 고안한 스크류 타입의 런너을 이용하여 캐비티간 충전균형을 고찰하였다. 여러 형태의 스크류 런너에서 결정성 수지와 비결정성 수지, 그리고 점도가 높은 수지와 점도가 낮은 수지를 이용하여 캐비티간 흐름을 관찰하였다. 흐름의 균형은 성형조건 중 사출속도에 따라 다르게 나타나기 때문에 사출속도를 변화해 가며 관찰하였다. 실험 결과를 성형해석과 비교 검토하였으며 서로 잘 일치함을 확인할 수 있었다. 스크류 런너에서 수지가 흐르면서 스크류 채널을 따라 회전운동을 하여 스크류 단면에서 온도가 균일하게 됨을 확인하였다. 그리구 이러한 균일한 온도 때문에 캐비티간 흐름 균형이 이루어지고 있음을 확인하였다. 결론적으로 실험에 사용된 새롭게 고안된 스크류 타입의 런너는 캐비티간 충전균형을 이루는데 매우 효과적임을 실험과 해석을 통해 검증할 수 있었다.