• 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.

• Design & Manufacturing
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• 제14권2호
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• pp.49-55
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• 2020

Recently, when a new component of construction equipment is designed, a stamping process capable of producing parts having high appearance quality and precision has been gaining attention. However, in general, as it is developed based on existing parts made by welding metal sheets and tubes, frequent to die modification occurs, which increases the time and cost of developing new parts. Thus, it is necessary to reduce the cost by shortening the die development period. In this study, a stamping process was designed for the urea tank cover, which is a part for excavators, to reduce the die development period through sheet metal forming analysis. The stamping process was designed by determining the blank holding force after selecting the initial blank shape and size. The round value at the corner was modified such that formability is ensured. After selecting process parameters, the thickness reduction rate and spring-back effect were reviewed.

• 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.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.316-319
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• 2002

Injection mold is a manufacturing process used to produce parts of complicated shape at a low cost. Many factors affect the quality of injection molded part during injection molding process. A study on the optimization of injection mold is progressed by using a simulation software like Moldflow. Filling, packing and cooling phases of injection molding processes are analyzed according to the mold design considering the shrinkage of molded part, the degree of filling rate and the wearing of a mold. Taguchi method is applied to analyze the significance of processing parameters and the dynamic characteristics according to the variation of processing parameters. From the results, the mold temperature and packing pressure influenced strongly the shrinkage of injection molded part.

• Design & Manufacturing
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• 제14권2호
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• pp.34-41
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• 2020

Typical characteristics of medical device parts are that they can not be reused and there are many disposable products. Therefore, there is a need for an injection molding machine having excellent repeatability of molding conditions and a precision injection mold for mass production. Recently, the performance of an injection machine has made a remarkable evolution compared to the past. However, defects such as short-shot, flash, weld line, gas burning, warpage, and deformation, which are typical defects, still do not disappear at all. This is due to the lack of gas ventilation from the product cavities, even if the gas is smoothly vented from the sprue and runner of the mold. For this reason, the internal pressure of the cavity rises and is directly connected to the quality defects. In this study, an active gas vent system was designed to prevent defects due to trapped gas in the cavity. Since it can be easily adjustable in response to the molding conditions and the mold temperature changes, it is expected to improve productivity due to the reduction of the defective ratio.

• 한국주조공학회지
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• 제22권4호
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• pp.192-199
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• 2002

Dimensional defects of castings are mainly due to the stresses and strains caused by a nonuniform temperature distribution and phase transformation during solidification and cooling, and by mechanical constraint between the mold and casting. It is, however, nearly impossible to trace movements of the casting and mold during solidification and cooling by experimental measurements for castings with complex shape. Two and three dimensional deformation analyses of the casting and the mold were performed using commercial finite element code, MARC. It was possible to calculate deformation and temperature distribution in the casting and mold simultaneously. Cooling curves of the casting obtained by calculation were close to that measured in the field since it was possible to treat latent heat evolution of the casting which could be divided into two parts, primary and eutectic parts. Mold bent inward just after pouring due to the temperature gradient across the mold thickness, and mold returned to its previous position with time. Plastic deformation occurred at the part of the casting where solidification was slow.

• 한국정밀공학회지
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• 제20권12호
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• pp.115-125
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• 2003

The design methodology of plastic injection molding die has been gradually moved from two-dimensional line drawings to three-dimensional solid models. The 3D design gives many benefits, a few of which are: ease of design change, data associativity from concept design to final assembly. In the paper represented is the implementation of a program which automatically generates 3D mold-bases and cooling-lines, conforming to given geometric constraints. It utilized a commercial CAD software and the related API(application program interface) libraries. We constructed a DB(database) of typical mold-bases assembled from standard parts, from which the geometry (position & dimension) of a mold-base and composed parts can be automatical]y determined by a few key parameters. Also we classified cooling lines into several typical types and constructed a DB, from which the position of cooling lines is automatically determined. The research is expected not only to simplify construction of a 3D mold-base model including cooling lines but also to reduce design efforts, by way of databases and automatized determination of geometric dimensions.

• 한국산학기술학회논문지
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• 제10권1호
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• pp.186-193
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• 2009

본 논문에서는 전열(마이크로 히터, 센서)을 이용해 금형의 표면을 가열하는 E-MOLD 특허기술을 적용하여 휴대전화용 복합기능 도광판(Prismless LGP)을 제작하고, 전사성을 평가하였다. 이를 위하여 MEMS 공정을 이용하여 복합기능 도광판용 니켈 스탬퍼를 제작하였고, E-MOLD 기술의 핵심인 이동가열코어(movable heated core)가 설치된 금형을 설계, 제작하였다 이를 이용하여 성형조건 중 금형온도를 변화시키면서 복합기능 도광판을 사출성형으로 제조 하였고, 금형온도가 성형품의 전사성에 미치는 영향에 대하여 알아보았다. 또한, 전산모사 프로그램(CAE)을 이용하여 금형온도와 사출시간에 따른 수지의 유동성을 해석하였다. 금형온도에 따른 도광판의 전사성은 $100^{\circ}C$(25.0nm), $140^{\circ}C$(48.4nm), $180^{\circ}C$(52.1nm)로 나타났고, 스탬퍼(52.1nm)와 비교했을 때 $180^{\circ}C$에서 전사성이 가장 우수했다. 전산모사 해석결과에 따르면, 수지의 유동성은 금형온도($50{\sim}180^{\circ}C$)가 증가할수록 향상되었다. 사출시($1{\sim}2sec$)이 길수록 유동성이 감소하는 경향을 $160^{\circ}C$에서 확인하였다. 따라서 수지의 전사성과 유동성은 금형온도에 따라 증가하고, 특히 유리전이 온도($140^{\circ}C$) 이상에서 크게 상승하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.623-624
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• 2005

Micro injection molding is a branch of micro system technology and has been under development for the mass manufacture of micro parts. Enhanced technological products like micro optical devices are entering the market. This paper presents fundamental research on the injection molding technique in micro fabrication. In order to successful manufacturing of micro plastic parts, it is necessary to research for development of micro-injection machine, machining of micro mold, decision of optimum injection conditions and the research for polymer material. Therefore in this study, in order to machining of micro mold, a mold core with microscopic V-shaped groove was tooled by ultra-precise tooling machine. The transcription experiments with a polymer, PMMA resin on the surface of core with Ni plating were carried out and surface profile of injected parts was measured with AFM.

• 한국생산제조학회지
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• 제19권5호
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• pp.660-666
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• 2010

In cellphone optical systems, a tiny difference of manufacturing has a strong influence on camera lenses. This study aims to find out the worst result by tolerances come from all parts in optical performance. First, 3D Measure Instrument, Roundness Measure Instrument, and Wavelength Measure Instrument were used for greater precision by making and measuring the parts to see how different from the drawings. It was confirmed that even narrow tolerances could result in defects by assembling. Tolerances in assembly should be concerned as those in parts through the research.