• Journal of the Korean institute of surface engineering
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• v.35 no.3
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• pp.113-120
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• 2002

Injection molded plastic parts have many surface defects. These include a weld line, sink mark, flow mark, gloss, shading, scratching etc. Because these surface faults are not aesthetically acceptable, plastic parts are produced through painting or texturing. The purpose of this paper is to develop paintless molded parts using a flow control method. Computer aided injection mold filling simulations were used in order to minimize the number of defects from injection molding. Based on the numerical results, FR(Flame Retardant) HIPS was developed and the guidelines for part design, mold design, and the processing conditions were established. The effects of cost savings, improvements in productivity, and recycling were considered by reducing the number of surface faults and eliminating the painting process.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.10a
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• pp.266-270
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• 2007

Small injection molded articles such as lens and mobile product's parts are usually molded in multi-cavity mold. The problems occurred in multi-cavity molding are flow imbalance among the cavities. The flow imbalance affects on the dimensions and physical properties of molded articles. First of all, the origin of flow imbalance is geometrical imbalance of delivery system. However, even the geometry of delivery system is balanced well the cavity imbalance is being developed. This comes from the unsuitable operational conditions of injection molding. Among the operational conditions, injection speed is the most significant process variable affecting the filling imbalances in multi-cavity injection molding. In this study, experimental study of flow imbalance has been conducted for various injection speeds and materials. Also, the filling Imbalances were compared with CAE results. The dimensions and physical state of multi-cavity molded parts were examined. The results showed that the filling imbalances vary according to the injection speed and flow property of resins. Subsequently, the imbalanced filling and pressure distribution in the multi-cavity affect on the dimensions and physical states of molded parts.

• Journal of the Semiconductor & Display Technology
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• v.6 no.3
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• pp.7-11
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• 2007

The design and manufacture of injection-molded parts with desired properties is a costly process dominated by empiricism, Including the repeated modification of actual tooling. The objective of this study is to obtain the good design of injection-molded polymeric parts using axiomatic design approach.

• Design & Manufacturing
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• v.13 no.4
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• pp.34-39
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• 2019

In this paper, in order to improve the formability and quality of the injection molded parts in the molds for molding the motorcycle rear cowl injection molded parts with different volumes at the same time, the flow of the molded parts is changed through the injection molding CAE analysis by changing the gate position, runner size and position. It is to find the optimum gate position, the diameter of the runner and the position where the balance is equal. The molded article formed by the optimization resulted in the uniformity of the molten resin at the same time at the corner of the product, thereby maintaining the flow balance favorable for mass production at lower injection pressure.

• Elastomers and Composites
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• v.52 no.4
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• pp.309-316
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• 2017

In injection molding, the quality of an injection molded product varies greatly depending on the molding conditions. Many researche studies have been conducted on the quality analysis of molded parts according to the molding conditions such as injection pressure, injection temperature, and packing pressure. However, there have not been many studies on the V/P switchover timing. It is known that when a large pressure is applied to a cavity in the packing phase, the cavity pressure is most affected by the packing pressure. In addition, depending on the position (timing) of the packing pressure, it can have a direct influence on quality based on the shrinkage and dimensions of the molded parts. In this study, the change in pressure profile in the cavity according to the V/P switchover position is confirmed. A CAE analysis program (Moldflow) was used to simulate and analyze two models using the PC and PBT materials. In order to compare these results with the actual injection molding results, injection molding was performed for each V/P switchover position, and the correlation between simulation and experiment, especially for the shrinkage of molded parts, was evaluated.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2005.05a
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• pp.109-114
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• 2005

The large injection molded parts technology such as instrument panel, front and rear bumper are presented for a precision molding. Some lead time and cost are required to product these part from design to mass product. Recently, CAE is widely used in product design, mold design and analysis of molding conditions to reduce time and cost. The optimal molding conditions can be obtained by DOE(Design of Experiment). The optimal design applications with CAE and DOE have been used in small molded parts. However, application to the large molded body is not reported. In this paper, optimization of injection molding process is studied for quality control in mass production of automobile bumper. Mold temperature difference is chosen through robust design of injection molding process, the molding process being optimized in term of shrinkage and deflection. The optimal conditions through DOE are validated by using injection molding analysis.

• 제어로봇시스템학회:학술대회논문집
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• 1986.10a
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• pp.431-436
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• 1986

The design and manufacture of injection molded polymeic parts with desired mechanical properties is a costly process dominated by empiricism, including the modification of actual tooling. This paper presents an interactive computer-based design system for injection molded plastic parts. This knowledge-based synthesis system provides a rational design strategy for injection molding and molded parts. It synergistically combines a rule-based expert system for hurestic knowledge with analytical process simulation programs. The theremomechanical properties of a molded part such as the effect of molecular orientation and weldline strength are predicted by the analysis programs; while the expert system interprets the analytical results from the process simulation, evaluates the design, and generates recommendations for optimal design alternatives. The heuristic knowledge of injection molding is formalized as production rules of the expert consultation system.

• Polymer(Korea)
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• v.32 no.6
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• pp.501-508
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• 2008

Small injection molded articles such as lens and mobile product parts are usually molded in multi-cavity mold. The problem occurring in multi-cavity molding is flow unbalance among the cavities. The flow unbalance affects the dimensions and physical properties of molded articles. First of all, the origin of flow unbalance is geometrical unbalance of the delivery system. However, even the geometry of the delivery system is well balanced, cavity unbalance occurs. This comes from the temperature distributions in the cross-section of runner. Temperature distribution depends upon injection speed because heat generation near runner wall is high at high injection speed. Among the operational conditions, injection speed is the most significant process variable affecting the filling unbalances in multi-cavity injection molding. In this study, experimental study of flow unbalance has been conducted for various injection speeds and materials. Also, the filling unbalances were compared with CAE results. The dimensions and weights of multi-cavity molded parts were examined. The results showed that the filling unbalances vary according to the injection speeds and resins. Subsequently, the unbalanced filling and pressure distribution in the multi-cavity affect the dimensions and physical states of molded parts.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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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.

• International Journal of Precision Engineering and Manufacturing
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• v.1 no.1
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• pp.133-145
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• 2000

Plastic molding designers are frequently faced with optimizing multiple defects in injection molded parts. these defects are usually in conflict with each other, and thus a tradeoff needs to be made reach a final compromised solution. In this study, an automated injection molding design methodology has been developed to optimize multiple defects of injection molded parts. Two features of the proposed methodology are as follows: one is to apply the utility theory to transform the original multiple objective optimization problem into single objective optimization problem with utility as objective function, the other is an implementation of a direct search-based injection molding optimization procedure with automated consideration of process variation. The modified complex method is used as a general optimization tool in this research. The developed methodology was applied to an actual molding design and the results showed that the methodology was useful through the CAE simulation using a commercial injection molding software package. Applied to production, this study will be of immense value to industry in reducing the product development time and enhancing the product quality.