• 대한기계학회논문집A
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• 제21권9호
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• pp.1470-1479
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• 1997

In this study, the plastic fan with high efficiency and low noise was designed and the capacity of the wind and the wind pressure were analysed and verified by CAE. After designing the metallic mold using the metallic mold design data, and the the metallic mold design was reformed by analysing the process of the material stream and injection filling by CAE. Also the metallic mold cutting data were formed using the metallic mold design data. These cutting data was used to produce the fan electrode by a machining center and then this electrode were used to manufacture the metallic mold by cutting the fan cavity by an electrical spark machine. The purpose of this study is to find out the sub-optimal condition on the productivity and improvement in quality of the plastic fan by integrating a series of this process with a computer.

• Design & Manufacturing
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• 제8권1호
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• pp.10-13
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• 2014

Plastic products are producted more than 70% of total processes by the injection molding. The injection molding process has 4 processes such as filling, packing, cooling and ejecting. It spends most of times in the cooling process. Therefore, it is important to control the mold temperature in producing plastic products. The time and system of cooling affect the product's quality and productivity. Especially, cooling time has about 60% of total injection cycle time. Therefore, we can improve a productivity by shortening cooling time. This study shows comparative study about cooling efficiency of spiral channel and baffle and observed the variation of time to freeze of molding As the result of CAE experiments, cooling rate by spiral channel had faster than baffle and as freeze time was decreased. Results of this study will be used widely to design for cooling system of injection mold.

• 한국분말재료학회지
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• 제14권3호
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• pp.202-207
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• 2007

Novel polymer mold process for fabrication of microcomponents using metal nanopowders was developed and experimentally optimized. Polymer mold for forming green components was produced by using a hard master mold and polydimethylsiloxane (PDMS). In the preparation of metallic powder premix for the green components without any defect, 90 wt.% 17-4PH statinless steel nanopowders and 10 wt.% organic binder were mixed by a ball milling process. The green components with very clear gear shape were formed by filling the powder premix into the PDMS soft mold in surrounding at about $100^{\circ}C$. Cold isostatic pressing (CIP) was very potent process to decrease a porosity in the sintered microcomponent. The microgear fabricated by the improved process showed a good dimension tolerance of about 1.2%.

• 유변학
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• 제10권4호
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• pp.217-226
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• 1998

단섬유 강화 고분자의 사출성형시 고분자 수지의 유동에 의하여 섬유배향이 필연적으로 일어나며, 섬유배향에 의한 이방성 (anisotropy)은 최종성형물의 품질과 기계적인 특성 등에 많은 영향을 미친다. 사출공정 중에서 충전과정(filling stage)은 섬유배향에 지배적인 역할을 하므로, 충전과정의 유동장을 정확하게 해석하는 것은 매우 중요하다. 형상이 복잡한 캐비티(cavity)와 다중 캐비티에서는 먼저 충전이 완료되어 현탁액(suspension)이 압축을 받고 있는 영역들이 존재하게 된다. 기존의 방법처럼 사출성형의 충전과정을 비압축성 유동으로 가정하면 정확한 유동장을 계산할 수 없다. 본 연구에서는 충전과정에서 압축성을 고려한 혼합 유한요소법/유한차분법을 이용하여 유동장을 계산하였다. 충전이 완료되는 순간에서, 이차배향텐서에 대한 배향변화방정식을 4차 Runge-Kutta 방법을 이용하여 해석함으로써 3차원 섬유배향장을 예측하였다. 충전시간이 다른 4개의 캐비티를 갖는 금형을 제작하여 충전과정에서 압축성 효과를 고려한 수치해석 결과가 실험과 잘 일치함을 보였다. 또한, 압축성과 비압축성 유동장에서 이론적으로 계산된 섬유배향의 차이를 정성적 및 정량적으로 비교하였다.

• 한국기계가공학회지
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• 제13권4호
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• pp.21-27
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• 2014

The injection molding process has several advantages enabling it to produce large quantities of molded plastic products using a repetitive process. In recent years, it has been necessary to develop an injection molding process with micro/nano-sized patterns for application to the semiconductor industry and to the bio/nano manufacturing industry. In this study, we apply gas pressure to the inside of a mold and consider the gas dissolution phenomenon for a resin filling into a micro pattern with a line structure. Using numerical analysis, we calculate the filling ratio with respect to time for various internal gas pressures and various aspect ratios of the micro-patterns.

• 한국생산제조학회지
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• 제22권3호
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• pp.472-479
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• 2013

We carried out research into an environmentally friendly injection molding process that involves filling the mold with polymer after thin films are fixed into the cavity, without the coating, plating process. Film insert injection molding is a new technique in which molten plastic resin is injected into the cavity after films are precisely attached to the side of the mold wall. In the film insert injection molding process, the insert film is moved by the flow of the molten plastic resin. Overlap defects cause a decline in the productivity and the quality of the manufactured goods. To reduce overlap defects, new injection mold parts are proposed to produce automotive exterior parts using thin films. It is suggested that the best possible method would be to fix the thin films to one side of the mold wall, and develop interior pins to fix the films in the mold. Based on this new pin fixing system, the problem of the film being moved by the flow of the molten resin was improved.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2001년도 추계학술대회 학술발표 논문집
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• pp.65-68
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• 2001

Short shot is a molded part that is incomplete since insufficient material was injected into the mold. Remedial actions to solve short shot can be done by injection molding experts based on their empirical knowledge. Modifying mold and part, changing resin to less viscous one, and adjusting process conditions are general remedies. Experts of injection molding might try to adjust process conditions such as mold temperature, melt temperature, injection time based on their empirical knowledge as the first remedy because adjustment of process conditions is the most economic way in time and cost. However it is difficult to find appropriate process conditions as they are highly coupled and there are so many elements to be considered. In this paper, a fuzzy logic algorithm has been proposed to find an appropriate mold temperature. With the percentage of the insufficient Quantity of an injection molded part, an appropriate mold temperature can be obtained by the fuzzy logic algorithm.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제2권1호
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• pp.49-52
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• 2002

Short shot is a molded part that is incomplete since insufficient material was injected into the mold. Remedial actions to solve short shot can be dune by injection molding experts based on their empirical knowledge. Modifying mold and part, changing resin to less viscous one, and adjusting process conditions are general remedies. Experts of injection molding might try to adjust process conditions such as mold temperature, melt temperature, injection time based on their empirical knowledge as the first remedy because adjustment of process conditions is the most economic way in time and cost. However it is difficult to find appropriate process conditions as they are highly coupled and there are so many elements to be considered. In this paper, a fuzzy logic algorithm has been proposed to find an appropriate mold temperature. With the percentage of the insufficient quantity of an injection molded part, an appropriate mold temperature can be obtained by the fuzzy logic algorithm.

• 대한기계학회논문집A
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• 제32권6호
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• pp.481-487
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• 2008

Rapid mold heating has been recent issue to enable the injection molding of thin-walled parts or micro/nano structures. Induction heating is an efficient way to heat material by means of an electric current that is caused to flow through the material or its container by electromagnetic induction. It has various applications such as heat treatment, brazing, welding, melting, and mold heating. The present study covers an experimental investigation of induction heating in order to rapidly raise the mold temperature. It is observed that the mold surface temperature is raised up to $200^{\circ}C$ in 2 seconds. This induction heating is applied to injection molding of a flexspline for a plastic harmonic drive, which has difficulty in cavity filling because its minimum thickness is only 0.35 mm. The induction heating is then successfully implemented on this ultra-thin wall molding by raising the mold surface temperature around the glass-transition temperature of the molding material.

• 한국주조공학회지
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• 제33권5호
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• pp.204-209
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• 2013

The family mold casting have advantages which are able to make products with different shapes and dimensions simultaneously in a single mold. In this study, the design of the 4 cavity rotor family mold was used by "Anycasting" software, the defects occurred during die casting were predicted and suggested the best optimization conditions for sound products. The result of the experiment were that the optimum overflow design was needed for gas emission and control of residual oxides. It was clear that the defects positions formed by diecasting were agreed with nearly them predicted by simulation.