• 품질경영학회지
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• 제29권3호
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• pp.86-96
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• 2001

The objective of this research is to develop a robust design methodology for plastic injection molded parts wherein warpage will be minimized by a complex method which is a kind of a simple direct search method. The design space considered for optimization is divided Into two sub-design space : mold and process conditions. Warpage is quantified using the Moldflow injection molding simulation software. The design methodology was applied to an actual part of a fax machine, the Guide-ASF model, through two different design policies. The significance of this study is the synthesis of a computer simulation of injection molding process and optimization technique to determine the optimal robust design solution.

• Design & Manufacturing
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• 제6권1호
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• pp.90-94
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• 2012

Recently, injection molding process became more popular than ever to produce large quantities of high precision products. Extensive studies have been conducted for reducing the residual stresses and birefringence in injection-molded optical products. Flow-induced and thermally-induced stresses and birefringence have been found as two main sources during injection molding process. Generally, quantitative value of birefringence can be measured with polarizing microscope using the compensator. However, it is difficult to measure low order retardation with microscope, so developing a measurement system for low order optical path difference is in need. In the present paper, a system using Photo Elastic Modulator (PEM) is demonstrated to measure low phase retardation in injection-molded products.

• 동력기계공학회지
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• 제13권4호
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• pp.38-42
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• 2009

The Injection molding is used more than 70% of total production in plastic products. The injection molding process has 4 processes such as filling, packing, cooling and ejecting. now then, cooling process spends the most of times in Injection molding cycle time. Therefore, it is important to control the mold temperature in producing plastic products. The cooling system and time 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. In this study, the rapid cooling system was developed and performed a efficiency test. This system could refrigerate coolant to $1^{\circ}C$ and had to need 10 minutes for normal operating.

• 소성∙가공
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• 제21권2호
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• pp.126-130
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• 2012

Accurate optical texturing of light guide plate over the entire surface area is an important technical issue in LCD TV industry. Injection molding process has the potential to produce large light guide plates having highly efficient optical textures such as micro-prism array. This study is focused on the effect of the degree of replication of the micro texture of the 40" injection molded light guide plates on the overall optical performance of the display panel. Measured replication ratios of the micro-textures formed with three different types of injection molding process were considered in the modeling of prismatic micro segment array. Optical simulation was conducted and results were discussed.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.996-999
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• 2008

Aspheric polymer lens fabrication using isothermal compression molding is presented in this paper. Due to increasing definition of an image sensor, higher precision is required by a lens which can be used as a part of an imageforming optical module. Injection molding is a factory standard method for a polymer optical lens. But achievable precision using injection molding has a formidable limitation due to the machining of complex mold structure and melting and cooling down a polymer melt under high pressure condition during forming process. To overcome the precision requirement and limitation using injection molding method, isothermal compression molding is applied to fabrication of a polymer optical lens. The fabrication condition is determined by numerical simulations of temperature distribution and given material properties. Under the found condition, the lens having a high precision can successfully be reproduced and does not show birefringence which results often in optical degradation.

• 대한기계학회논문집A
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• 제31권5호
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• pp.556-561
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• 2007

The rapid thermal response(RTR) molding is a novel process developed to raise the temperature of mold surface rapidly in the injection stage and then cool rapidly to the ejection temperature by air or water. The objectives of this paper are to investigate the effect of mold temperature, pressure and thickness of micro pattern molding and to provide a optimization of RTR injection molding for micro pattern from Moldflow simulation. Optimal minimum temperature and pressure was found without shortcut according to thickness. Filling percentage was influenced by glass transition temperature with the kinds of resin. Optimal temperature is slightly higher than glass transition temperature irrespectively of pressure, thickness, the kinds of resin in the micro pattern molding.

• 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 $140^{\circ}$.

• 대한기계학회논문집A
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• 제38권7호
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• pp.771-777
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• 2014

자동차용 도어그립을 대상으로 하여 3 차원 엠보 패턴이 인쇄된 필름을 적용한 인서트성형을 구현하기 위하여 사출압축성형을 사용하였다. 진공금형을 제작하여 필름 열성형을 하였으며, 필름인서트성형을 위하여 사출압축금형을 개발하였다. 3 개의 압력센서를 설치하여 금형 캐비티압력을 측정하였으며, 다양한 압축스트로크와 토글속도에 대한 사출압축성형 실험을 수행하여, 공정조건이 캐비티 압력과 엠보 패턴의 높이에 미치는 영향을 고찰하였다. 압축스트로크 0.9mm와 느린 토글속도에서 엠보 패턴의 유지율이 높게 나타났다. 또한 엠보패턴이 최대 높이를 갖기 위한 공정조건은 캐비티 압력의 적분값이 최소가 되는 조건과 거의 동일하였다. 사출압축성형을 사용하여 엠보 패턴이 인쇄된 소프트한 촉감을 갖는 플라스틱 제품을 구현할 수 있다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.343-344
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• 2006

Powder injection molding(PIM) is widely used for many parts in the field of automotives, electronics and medical industries, due to the capability of net shaping for complex 3-D geometry. Powder injection mold design fur the dental scaler tip, a component of medical appliance, was presented. In comparison with conventional machining process, powder injection molding has many advantages, specially in price and dimensional stability, for molding dental scaler tip which has complex geometry. Both product design and mold design for dental scaler tip were presented. The 'rapid mold' concept was applied to manufacture the various forms of dental scaler tip.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1206-1209
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• 2005

In recent, injection molding process for features in sub-micron scale is under active development as patterning nano-scale features, which can provide the master or stamp for molding, and becomes available around the world. Injection molding has been one of the most efficient processes for mass production of the plastic product, and this process is already applied to nano-technology products successfully such as optical storage media like DVD or BD which is a large area plastic thin substrate with nano-scale features on its surface. Bio chip for like DNA sequencing may be another application of this plastic substrate. The DNA can be sequenced using order of 100 nm pore structure when making the DNA flow through the pore structure. Agarose gel and silicon based chip have been used to sequence the DNA, but injection molded plastic chip may have benefit in terms of cost. This plastic DNA sequencing chip has plenty of pillars in order of 100 nm in diameter on the substrate. When the usual features in case of DVD or BD have very low aspect ratio, even less than 0.5, but the DNA chip will have relatively high aspect ratio of about 2. It is not easy to injection mold the large area thin substrate with sub-micron features on its surface due to the characteristics of the molding process and it becomes much more difficult when the aspect ratio of the features becomes high. We investigated the effect of the molding parameters for injection molding with high aspect ratio nano-scale features and injection molded some plastic DNA sequencing chips. We also fabricated PR masters and Ni stamps of the DNA chip to be used for molding