• Composites Research
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• 제16권6호
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• pp.10-15
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• 2003

RTM 공정에 의하여 생성된 제품은 microvoids의 함유량에 의하여 기계적인 물성치에 큰 영향을 받는다. 본 연구에서는 이러한 microvoid의 형성과 이동을 실험적으로 관찰할 수 있는 방법을 제시하였다. Vacuum assisted RTM공정에서 유동선단에서의 microvoid의 형성과 이동을 DV camera로써 관찰을 한 후, 그것에서 void의 함유량을 구하고, 실험에서 얻어진 결과로 microvoid model에 필요만 factor들을 얻어낼 수 있었다. 이렇게 하여 얻어진 결과를 다시 실험적인 결과와 비교함으로써 서로 일치하는 결과를 얻어낼 수 있었다. 이번 연구에서 얻어진 결과를 수학적인 모델에 대입함으로써 VARTM 공정 중 microvoid의 함유량을 예측할 수 있다.

• 한국전기전자재료학회논문지
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• 제11권5호
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• pp.353-357
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• 1998

Cracking problem of Epoxy Molding Compound(EMC) is critical for the reliability of the plastic package during temperature cycling and IR-reflow condition. Fracture toughness of EMC, which is defined as the resistance of EMC to the crack propagation, is a useful factor in ht estimation of EMC against package crack. Thus, development of EMC having high fracture toughness at a given loading condition would be important for confirming the integrity of package. In this study, toughness of several EMC was measured by varying the test conditions such as temperature, loading speeds, and weight percent of filler in order to quantify the variation of toughness of EMC under various applicable conditions. It was found from the experiments that toughness of all EMC has following trends, i.e., it rapidly decreases over the glass transition temperature, remains almost same or little decreases below $0^{\circ}C$. It decreases with the growth of cross head speed in EMC and the weight percent of filler as the degree of brittleness of EMC increases with the amount of filler content.

• 한국기계가공학회지
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• 제18권11호
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• pp.1-8
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• 2019

In this study, we design the feed system and process conditions for a lamp garnish lens of an automobile. For this purpose, four design alternatives are presented and injection molding simulation analyses are performed. The optimal feed system is selected by considering the formability of the product and the cost of mold manufacture. The product formability is assessed by the weld line, warpage, sink mark and the maximum injection pressure, whereas the mold-making cost is estimated by the number of valve gates in the hot runner system. To improve the product formability, process conditions are optimized using an experimental design approach named one-factor-at-a-time. No weld line is generated as a result of the optimization. In addition, it is found the warpage and sink mark are reduced while the maximum injection pressure is increased, compared with those before the optimization.

• Design & Manufacturing
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• 제17권3호
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• pp.21-27
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• 2023

The mold industry in Japan, an advanced country in the mold industry, is also at a point of great change. The main causes are the Ukraine crisis and the collapse of the global supply chain (parts supply chain) caused by COVID-19. In addition, the prices of overseas products are rising sharply due to rapid exchange rate fluctuations (decrease in the value of the yen). Until now, Japan's monotsukuri industry has been actively pursuing overseas expansion, riding the trend of globalization. However, the trend began to rapidly reverse, and now the monotsukuri industry that had expanded overseas is showing a tendency to return to Japan. Another factor of change is the change in the automobile industry, which is the most demanded product in the mold industry. As the automobile industry evolves from gasoline cars to electric cars, the number of parts that make up a car will drastically decrease. This trend is expected to increase the demand for small-scale production of a variety of products in the mold industry, and furthermore, it is expected that short delivery times will be required in parts development. As in Korea, the production population working in the mold industry is rapidly decreasing in Japan as well. Even if you add up the total population working in manufacturing in Japan, it only accounts for about 15%. Even in Japan, it is judged that it will be difficult to sustain the monotsukuri industry with this small production population. Therefore, since improvement in production efficiency cannot be expected with the same manual dexterity as before, the mold industry is also demanding the development of mold technology at a different level than before to increase productivity. In this paper, I would like to introduce new Japanese mold technology collected through attending the Intermold exhibition. This is an example of applying a dedicated pin (Gastos) to a mold to prevent an increase in internal pressure during plastic injection molding, and a deep drawing press molding technology with an inherent hydraulic function.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.811-814
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• 2001

Warpage analysis of bobbin, molded by injection molding process was performed. Concerned with a mold design, cooling system was designed based on Taguchi method, the distance between cavity wall and cooling channel was most influent factor amongst four design variables like an inlet temperature of coolant, a coolant flow rate, a diameter of cooling channel, and the distance between cavity wall and cooling channel. Optimal packing processes to reduce the warpage of molded part was analyzed based on the response surface method by considering holding pressure. Their optimal processing conditions were 9.4 seconds, 5.3 seconds, 15.2 seconds, and 85MPa, respectively.

• 마이크로전자및패키징학회지
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• 제5권2호
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• pp.37-48
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• 1998

The popcorn cracking phenomena in plastic IC packages during reflow soldering are investigated by considering the heat transfer and moisture diffusion through the epoxy molding compound(EMC) along with the mechanics of interface delamination. Heat transfer and moisture diffusion through EMC under die pad are analyzed by finite difference method (FDM)during the pre-conditioning and subsequent reflow soldiering pro-cess and the amounts of moisture mass and vapor pressure at delaminated die pad/ EMC interface are calculated as a function of the reflow soldering time. The energy release rate stress intensity factor and phase angle were obtained under various loading conditions which are thermal crack face vapor pressure and mixed loadings. It was shown that thermal loading was the main driving force for the crack propagation for small crack lengths but vapor pressure loading played more significant role as crack grew.

• 한국기계가공학회지
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• 제7권1호
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• pp.53-61
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• 2008

In this research, the layout and geometry of U-type ribs in the part, including significant process conditions, are automatically optimized to reduce part warpage with robustness in consideration. The optimization procedure are based on an iterative redesign methodology integrated with computer aided injection molding simulation, Taguchi's Design of Experiment(DOE), and a direct search-based optimization method. The robustness of a design alternative is efficiently measured by introducing composite noise factor and Taguchi's signal-to-noise ratio. As a solution search methodology, the modified design space reduction method based on orthogonal arrays is employed to exploit an optimal robust design alternative. To illustrate the proposed methodology, a case study is performed on simulation results, where an optimal robust design alternative is obtained with a moderate number of iterations.

• 산업경영시스템학회지
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• 제25권2호
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• pp.71-76
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• 2002

Defining the relationship between the quality of Injection molded parts and the process condition is very complicate because of lots of factors are involved and each factor has a non-linearity. With the development of CAE(Computer Aided Engineering) technology, the estimation of volumetric shrinkage of injection mold parts is possible by computer simulation in spite of restricted application. In this research, the Taguchi method md Neural Network are applied for finding optimal processing condition. The percent of volumetric shrinkage is compared on each case and shows neural network can be successfully applied.

• 한국정밀공학회지
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• 제29권6호
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• pp.648-653
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• 2012

Cavity pressure, an important factor in injection molding process, should be minimized to enhance injection molding quality. In this study, we decided the locations of valve gates to minimize the maximum cavity pressure. To solve this problem, we integrated MAPS-3D (Mold Analysis and Plastic Solution-3Dimension), a commercial injection molding analysis CAE tool, using the file parsing method of PIAnO (Process Integration, Automation and Optimization) as a commercial process integration and design optimization tool. In order to reduce the computational time for obtaining the optimal design solution, we performed an approximate optimization using a meta-model that replaced expensive computer simulations. To generate the meta-model, computer simulations were performed at the design points selected using the optimal Latin hypercube design as an experimental design. Then, we used micro genetic algorithm equipped in PIAnO to obtain the optimal design solution. Using the proposed design approach, the maximum cavity pressure was reduced by 17.3% compared to the initial one, which clearly showed the validity of the proposed design approach.

• Design & Manufacturing
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• 제11권2호
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• pp.1-8
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• 2017

In this study, we applied microcellular foaming injection molding process to improve the performance of system air-conditioner drain fan which had been produced by injection molding process and studied the optimization of process conditions through 6-sigma process and response surface method (RSM) to reduce weight and deformation of products. Additive type, melt temperature, mold temperature, and injection screw shape were selected as the factor affecting the weight and deformation of the products by carrying out analysis of trivial many through ANOVA and design of experiment (DOE) method. Among the effect factor, we set the addictive type to Long G/F and screw shape to foaming screw which had the highest level of weight reduction and deformation reduction. The amount of foaming agent gas was set at 60 ml, which was the limit beyond which the weight of product did not decrease any more. For melt temperature and mold temperature, we studied the conditions where both weight and deformation were minimized using the RSM. As a result, we set the melt temperature to $250^{\circ}C$, fixed mold temperature to $20^{\circ}C$, and moving mold temperature to $40^{\circ}C$. The improvement effect was analyzed by appling the selected optimal conditions to the production process using the microcellular foaming injection molding. The results showed that the mean weight of product was measured to be 1,420g which was 19% lower than that measured in the current process. The standard deviations of the weights were found to be similar to those in the current process and it showed a low dispersion. The mean deformation was measured to be 0.9237mm, which represented a 57% reduction compared to the mean deformation in the current process, and the standard deviation decreased from 0.3298mm to 0.1398mm. Moreover, we analyzed the process capability for deformation, and the results showed that the short-term process capability increased from 2.73 to 6.60 which was even higher than targeted level of 6.0.