• Journal of Powder Materials
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• v.9 no.4
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• pp.245-250
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• 2002

In this paper we presented numerical method for the simulation of powder injection molding filling process, which is one of the key processes in powder injection molding. Rheological properties of powder binder mixture such as slip phenomena and yield stress were introduced into the numerical analysis model of powder injection molding filling simulation. Numerical model can be classified into two types. One is 2.5D model which can be introduced to a arbitrary thin geometry and the other is full 3D model which can be applied to a general 3D shape. For 2.5D model we showed the validity of our CAE system with several verification examples. Finally we suggested flow analysis model for 3D powder injection molding filling simulation.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.12
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• pp.129-135
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• 2021

Injection molding is a manufacturing method of melting the polymer resin and injecting it into a mold to molding it into the desired form. Due to the short molding time and outstanding formability, complex products can be shaped with high precision and it is the most widely used polymer molding method. However, there may be areas that are not filled depending on the location of the injection gate where polymer resin is injected. Formability is determined by deformation and surface precision due to the impact of residual stress after molding. Hence, choosing the location of the injection gate is very important and molding analysis of injection molding is essential to reduce the cost of the mold. This study evaluated the injection formability based on the location of the injection gate of the vertical machining center ATC tool port using injection molding analysis and the results were compared and analyzed. Injection molding analysis was conducted on filling, packing, and deformation according to the location of the gate of the ATC tool port. From each injection gate location, filling time, pressure, and maximum deformation were compared. At gate 2, conditions of molding time and the location of the gate were far superior in production and quality. Gate 2 produced the smallest deformation of 0.779mm with the best quality.

• Transactions of Materials Processing
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• v.14 no.4 s.76
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• pp.368-374
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• 2005

In the present study we used a diagrammatic analysis of 6 sigma quality control and Taguchi method for injection molding of monitor back-cover, evaluated the influence on the cycle time with part design, mold design, molding process and standardization activity involving design and molding, adopted analysis of sensitivity and effective factors of the part design and molding process conditions for productivity, identified main design molding factors. The contributing factors for the final cycle time could be enumerated as follows; the thickness of hot spot, main nominal part thickness, coolant inlet temperature, melt temperature and cooling line layout, etc.. As a first step, all the critical factors of design process applied to the current monitor housing were investigated through 6 sigma process. Thereafter, the optimal and better critical factors found in the first step were applied to new product design to prove that our process was correct. The Moldflow was used for injection molding simulation, and Minitab software for the statistical analysis, respectively. Finally, the productivity of new design was increased about 33 percents for our specific case.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.05a
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• pp.269-272
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• 2004

The present study used a diagrammatic analysis of 6 sigma quality control and Taguchi method for injection molding process of monitor back-cover, evaluated the influence on the cycle time with part design, mold design, molding process and standardization activity involving design & molding, adopted analysis of sensitivity and effective factors of the part design and molding process conditions for productivity, identified main design molding factors, as critical ones influencing on the quality and productivity, of which is summarized as design guidance. The main contribution factors for cycle time can be sequentially enumerated as follows; hot spot, part thickness, coolant inlet temperature, melt temperature cooling line layout, etc.. As a first step critical factors of the design process of current monitor housing were investigated. And the optimal and better critical factors found in the first step were applied to a new product proving our process was correct. Moldflow software was used for injection molding simulation, and Minitab software for the statistical analysis. Finally, the productivity was increased by about 33 percents for our specific case.

• Design & Manufacturing
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• v.2 no.5
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• pp.30-33
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• 2008

Injection Molding is the most effective process for mass production of plastic parts. The injection molding process is composed with several steps such as Filling, Packing, Holding, Cooling, Ejecting. Among them, filling and packing process should be considered carefully to improve accuracy of dimension, surface quality of plastic parts. Usually the quality above-mentioned is managed with weight of part after molding on the field. In this paper, a series of experiment for molding automotive front bumper was conducted with cavitity temperature sensor to optimize switch-over time(V-P switching), hot runner vale gate sequence time during filling and packing step for the purpose of uniform quality, weight at every molding. As a result, it was found that it is effective method to use temperature sensor in injection molding for quality control of plastic molding.

• Transactions of Materials Processing
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• v.4 no.1
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• pp.39-47
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• 1995

The compression molding of SMC (sheet molding compund) at room temperature was analyzed based on rigid-viscoplastic approach by three dimensional finite element program. The developed program was tested by solving the three dimensional compression of wedge type specimens of aluminum alloys at various processing conditions. The simulation results were compared well to the experimental results available in the literature. based on this comparison the program was proved to be valid and was further applied in solving compression molding of SMC, which is a thermosetting material reinforced with chopped fiber glass. To investigate the effects of friction conditions and mold closing speeds for compression molding of SMC charge at room temperature, compressions of the cylindrical and rectangular shaped SMC were analyzed for various friction conditions and mold closing speeds. The calculated load values were compared to the experimental results for the compression molding of cylindrical specimen.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.1
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• pp.57-62
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• 2009

Recently, with the increasing lightness and miniaturization of high resolution camera phones, the demand for aspheric glass lens has increased because plastic and spherical lens are unable to satisfy the required performance. An aspheric glass lens is fabricated by the high temperature and pressure molding using a tungsten carbide molding core, so precision grinding technology for the molding core surface are required. This paper reports a development of feedrate control grinding method for aspherical molding core using parallel grinding method. A plane molding core was ground using conventional and feedrate control grinding method. The performance of the feedrate control method was evaluated by measurement of surface roughness. The result indicated that the average surface roughness was reduced to 1.5 nm, which is more efficient than the conventional grinding method.

• Journal of Institute of Convergence Technology
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• v.5 no.1
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• pp.13-17
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• 2015

In wafer level molding progress, the thermal releasing failure phenomenon is shown up as the important problem. This phenomenon can cause the problem including the warpage, crack of the molded wafer. The thermal releasing failure is due to the insufficiency of adhesion strength degradation of the molding tape. To solve this problem, we studied experimental method increasing the release property of the molding tape through the plasma surface treatment on the wafer substrate. In this research, the vacuum plasma treatment system is used for release property improvement of the molding tape and controls the operating condition of the hydrophilic($O_2$, 100kW, 10min) and hydrophobic($C_2F_6$, 200kW, 10min). In order to perform the peeling test for measuring the releasing force precisely, we remodel the micro scale material property evaluation system developed by Korea institute of industrial technology. In case of hydrophilic surface treatment on the wafer substrate, we can figure out the releasing property of molding tape increase. In order to grasp the effect that it reaches to the release property increase when repeating the hydrophilic treatment, we make an experiment with twice treatment and get the result to increase about 12%. We find out the hydrophilic surface treatment method using plasma can improve releasing property of molding tape in the wafer level molding process.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.6
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• pp.945-952
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• 1987

In this paper, Crack molding method called "Teflon crack Molding Method" is developed. With help of this method, we can mold a crack which is very similar to the natural crack, which has the tip radius of about 20.mu. the vertical and horizontal quality of crack excellent. In addition to these, by using this method in photoelastic experiment we can obtain the clear crack tip location and Isochromatic fringe pattern boundary, therefore the precise in the experimental data can be improved. improved.

• Journal of Applied Reliability
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• v.17 no.3
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• pp.207-212
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• 2017

Purpose: This article provides an efficient cushion molding method for improving reliability of the rotation driving system. Method: Allowable stress level for cushion is calculated by using physical characteristics of the rotation driving system. In addition, various test units are manufactured and used to conduct the rebound resilience, the burst pressure and the alternating load test. Results: Actual allowable stress level and test results of the rebound resilience, the burst pressure and the alternating load test are provided. Conclusion: The cushion manufactured by the compression molding method gives more preferable characteristics for improving the reliability of the rotation driving system.