• Design & Manufacturing
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• v.17 no.1
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• pp.64-69
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• 2023

This paper explores the impact of gate shape changes on the size and density of foamed cells in microcellular foam injection molding. Five different gate shapes were examined while varying the amount of nitrogen gas(N2) injected for foaming. Analysis of the results showed that while average values did not change significantly, deviation values decreased by approximately 65% for cell size and 56% for density when 3.5wt% of nitrogen gas was injected in the film gate. Further analysis was conducted to verify this phenomenon, revealing that the contact area between the gate and product had the greatest impact. Our findings indicate that to ensure uniform generation of foamed cells in microcellular foaming product design, a gate with a wide contact area should be secured.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.6
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• pp.63-68
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• 2017

The purpose of this study is to improve the whitening phenomenon around the PET preform gate for blow molding. CAE analysis of plastic injection molding has been applied to design of preform shape and select the injection molding conditions. A ceramic insulation gate with lower thermal conductivity than metal is applied to improve the whitening phenomenon created around the gate in the injection molding process. According to the results of CAE analysis, the warpage deformation at the square corner was estimated to be about 0.34 mm at the bottom. From the results of the temperature history analysis, it was confirmed that the resin near the gate cooled more rapidly than the cavity. Ceramic insulated gates were fabricated to reduce the cooling rate and experiments were conducted to confirm the effectiveness of the whitening phenomenon improvement. As a result of the ceramic insulation gate experiment, it was confirmed that the whitening phenomenon was significantly reduced around the gate.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2002.02a
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• pp.125-131
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• 2002

Surface defects in injection molded parts are due to the unsteady flow of polymer melt which are related to the geometries of cavity and gate, the operational conditions of injection and the rheological properties of polymer. In this study we have examined jetting phenomena in injection molding process for three kinds of PCs which have different molecular weight and structure, PBT and PC/ABS alloy with several injection speeds. We have used various cavity shapes that are tensile, flexural and impact test specimens with various gate and cavity thicknesses. Through this study we have observed that the formation of surface defect associated with jetting during filling stage in injection molding is strongly related to die swell. This means that the jetting is strongly affected by the elastic property rather than the viscous property in viscoelastic characteristics of molten polymer. Large die swell would eliminate jetting however, the retardation of die swell would stimulate jetting. In the point of mold design, reducing the thickness ratio of cavity to gate can reduce or eliminate jetting and associated surface defects regardless of magnitude of elastic property. It also enlarges process window that can produce steady flow of polymer melt in injection molding.

• Design & Manufacturing
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• v.11 no.3
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• pp.13-18
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• 2017

The injection molding analysis of VCM (Voice Coil Motor) housing for smart phone cameras were performed. We conducted the analysis in terms of injection molding pressure, the formation of weld lines, flow marks, and flow patterns. The goal of the analysis was targeted for the prediction of the optimal gate locations. Because the quality of VCM housing is strongly dependent on the precise control of the camera lens by its nature, we focused on the lens guiding lanes in the VCM housing. We first calculated the maximum injection molding pressure in terms of the filled volumes. The injection molding pressure were calculated within 146MPa at about 90% volume filled. We also investigated the possibility of the occurrence of design-related defects such flow marks, weld lines. Filling patterns regarding the design of the gate locations were delineated to find the weld lines. Throughout the simulations, the final deformations of the lens guiding lanes for the VCM housing were calculated. The deformations distribute ranging from $0.5{\mu}m$ to $2.50{\mu}m$, which were used to find the optimal design of the gates.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.505-506
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• 2006

This study is focused on the manufacturing technique of powder injection molding of watch case made from zirconia powder. A series of computer simulation processes were applied to the prediction of the flow pattern in the inside of the mould and defects as weld-line. The material properties of melted feedstock, including the PVT graph and thermal viscosity flowage properties were measured to obtain the input data to be used in a computer simulation. Also, a molding experiment was conducted and the results of the experiment showed a good agreement with the simulation results for flow pattern and weld line location. On the other hand, gravity and inertia effects have an influence on the velocity of the melt front because of the high density of ceramic powder particles during powder injection molding in comparison with polymer's injection molding process. In the experiment, the position of the melt front was compared with the upper gate and lower gate positions. The gravity and inertia effect could be confirmed in the experimental results.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.1
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• pp.63-69
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• 2017

The golden section search method is widely used to optimize a single design variable in many fields due to its superior advantages of search. In this paper, a new direct search method is proposed by modifying the search structure of the golden section search method; thus, it can be adapted in the optimization of a single design variable for the injection molding process. This proposed method is applied to determine an optimal gate position for the injection molding of a bezel of an automated teller machine for minimizing the injection pressure. Thus, an optimal gate position where the injection pressure is decreased by 4.5 MPa to that of the initial position was obtained with a small number of simulations. It is anticipated that the current proposed search method can be utilized as a practical tool for optimizing single variables for injection molding design.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.6
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• pp.21-28
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• 2010

This study shows an optimization procedure for an automatic determination on the gate position to ensure the fill-uniformity within a part cavity by using the injection molding simulation. For an optimization, the maximum pressure-difference within a part cavity induced at the stage of filling is used to evaluate degree of fill-uniformity. In addition, a direct search scheme based on the reduction of design space is developed and applied in the optimization problem. This corresponding proposed methodology was applied in the optimization on the gate location for a CD-tray molding, as a result, showed the improvement of the fill-uniformity within the cavity.

• Transactions of Materials Processing
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• v.21 no.2
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• pp.96-100
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• 2012

Conventional injection molding system for producing extremely thin-wall parts such as Light Guide Plates(LGP's) for mobile displays is at the limit of its capability due to its tendency to develop frozen layers and the critical speed of injection. The molten polymer in the cavity freezes quickly as its heat is rapidly transferred to the mold base. Many attempts have been tried in the past to overcome this problem. The present study used the injection/compression molding technology to produce a thin-wall part, with enhanced features such as an automated mechanism for cutting gates. As a result, the total cycle time was reduced by almost 35 seconds, resulting in a productivity increase by 30%.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.3
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• pp.1-6
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• 2012

This study is focused on simulation technology in injection molding process for plastic optic lenses. The CAE program, $3D-TIMON^{TM}$ is used for the injection molding simulation with O-PET resin material. The design for different gate shape and runner layout has been under review by CAE simulation results. Moreover, the prediction of birefringence and polarized light in injection molded optic lenses has been tested by the CAE Program. The simulation results have been expected to effectively use in the design of injection molding mould.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.2
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• pp.289-295
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• 2010

Injection molding process is one of the most important methods to produce plastic parts with high efficiency and low cost. Today, injection molded parts have been increased dramatically the demand for high strength and quality applications. In this study, In-line skates are made of Al alloy and plastic materials to replace the frame for the optimization process is all about. I interpreted through mold design, Injection molding process that minimizes the runner and the gate dimension will determine the size and shape. Runner and gate dimensions of change based on availability of the product, I'll discuss the injection molding. This report investigates that the optimum injection molding condition for minimum of shrinkage. The FEM Simulation CAE tool, Moldflow, is used for the analysis of injection molding process.