• Journal of the Korean Society for Precision Engineering
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• v.21 no.2
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• pp.27-34
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• 2004

In the injection molding of plastic optical lenses, the molding conditions have critical effects on the quality of the molded lenses. Since there are many molding parameters involved in injection molding process, determination of the molding conditions for lens molding is very important in order to precisely control the surface contours of an optical lens. Therefore this paper presents the application of neural network in suggesting the optimized molding conditions for improving the quality of molded parts based on data of FE Analysis carried out through CAE software, Timon-3D. Suggested model in this paper, which serves to learn from the data of FE Analysis and induce the values for optimized molding conditions. has been implemented for searching the molding conditions without void and with minimized thickness shrinkage at lens center of injection molding optical lens. As the result of this study. we have confirmed that void creation at the inside of lens is primarily determined by mold temperature and thickness shrinkage at center of lens is primarily determined by the parameters such as holding pressure and mold temperature.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.11
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• pp.610-615
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• 2016

Diverse accessories are used in automobiles, such as navigation systems, front and rear cameras, spoilers, and sun visors. Sun visors block sunlight so that drivers can drive safely with a better view, and they are used in many automobile designs. However, when large plastic products are manufactured using injection molding, there are many difficulties that develop, like weld lines, short shots, flow marks, imperfections, and distortion. In this study, a CAE simulation was conducted based on previous results to predict potential problems in the injection molding of large products. The flow characteristics up to complete charge for the melting resins were captured using a computer-aided engineering simulation. The temperature departure on the front part of a flow was about $10^{\circ}C$ and very stable. The practical ejecting time of the cold runner was about 70 seconds in the simulation. Finally, the capability of a suitable injection machine was calculated and recommended by prediction of the injection pressure and the die clamping force.

• Design & Manufacturing
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• v.10 no.1
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• pp.19-25
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• 2016

Connectors are very important components that transmit electric signals to different parts. It must maintain intensity of the connector to prevent defects from impact and maintain contact to transmit electric signals. Most of the external parts of the connector, which act as the main framework, are formed by injection molding. However, bend deformation occurs for injection molded products due to the residual stress left inside the product after product molding. When the bend deformation is large, it does not come into complete contact when being assembled with other parts, which leads to connector contact intensity not being properly maintained. In result, the main role of the connector, which is to transmit electric signals, cannot be performed. In order to address this problem, this study conducted bend deformation cause analysis through bend deformation analysis to predict and prevent bend deformation of housings and wafers, which are injection molded products of pressure welded connectors that are normally applied in compact mobile and display products. Bend deformation analysis was carried out by checking the charging time, pressure distribution and temperature distribution through wire to board connector wafer and housing injection molding analysis. Based on the results of the bend deformation analysis results, the cause of the bend deformation was analyzed through deformation resulting from disproportional cooling, deformation resulting from disproportional contraction, and deformation resulting from ingredient orientation. In result, it was judged that the effects for bend deformation were biggest due to disproportional contraction for both the pressure welded connector wafer and housing.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.3
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• pp.159-165
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• 2002

So far, an alternator pulley has been formed by cold forging and casting with a metal due to the necessity of its high strength. Various advantages such as the light weight, the low cost, and the high productivity can be obtained by the injection molding process using engineering plastics. Engineering plastics have an excellent performance in the characteristics off strength vs. weight, a good forming ability and a productivity. The object of this study is to develop an alternator pulley, which has been made with a metal, using the injection molding process based on Taguchi methods. A sink mark is considered as a characteristic parameter to improve the quality. The FEM Simulation CAE tool, Moldflow, is used for the analysis of injection molding process.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.10a
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• pp.214-219
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• 2005

Pressure distribution in the cavity during injection molding affects part quality. In this study pressure distributions in the runner, near gate in the cavity, and end of ail in the cavity have been measured using direct pressure sensors for various molding conditions. Molding conditions were injection speed, injection pressure, packing time from filing stage, and packing pressure. Through experiments it was realized that the packing time from filling stage and packing pressure are the dominant factors on the part quality such as part shrinkage. Experimental results have been compared with computer simulations.

• Design & Manufacturing
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• v.2 no.2
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• pp.33-37
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• 2008

This paper describes the optimization of injection molding conditions to minimize sink marks. Sink marks, which refer to a small depression on the surface opposite a thick wall thickness, are often encounted in injection molded plastic parts. Part geometry, material properties and processing conditions during injection molding can affect the sink mark depth. We designed the runner system which is possible balanced filling to cavities using CAE program and then obtained optimal processing conditions by Taguchi's Robust Design technique. By actual injection molding using optimized mold and molding conditions, it confirmed that sink mark depth decreased zero compared to 1mm level in the conventional mold and process.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.7
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• pp.111-115
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• 2008

This paper describes the optimization of injection molding conditions to minimize sink marks. Sink marks, which refer to a small depression on the surface opposite a thick wall thickness, are often encounted in injection molded plastic parts. Part geometry, material properties and processing conditions during injection molding can affect the sink mark depth. We designed the runner system which is possible balanced filling to cavities using CAE program $Moldflow^{TM}$ and then obtained optimal processing conditions by Taguchi's Robust Design technique. By actual injection molding using optimized mold and molding conditions, it confirmed that sink mark depth decreased zero compared to 1mm level in the conventional mold and process.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.09a
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• pp.147-152
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• 2005

In recent industry, according to pursuit the miniaturization and high-precision of machine part with development of new technology as IT, BT the development of mold manufacturing technology for mass production is accompanied. In this study, the spiral type injection mold with a $200{\mu}m$ thickness shape is made for investigation of influence for injection molding process variables and the flow length is measured through an experiment. Beside, the result of each experiment Is compared with the analysis result of CAE. Taguchi method is used in this experiment and the obtained data are analyzed using ANOVA method.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.933-937
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• 1995

The design of injection molded prlymeric parts has been done empirically, since it requires profound knowledge about the moldability and causal effects on the properties of the parts. This study shows CAE approach for the design of the seat frame of fiber-reinforced composite material in order to realize the concept os rationsl design for the productivity and quality of mold making. The knowledge-based CAE system is constructed by adding the knowledge-basw module for the design evaluation and appropriate CAE programs for mold design analysis in order to provied designers, at the initial design stage, with comprehensive process knowledge for the performance analysis and the design evaluation. A knowledge-based CAE system is a new tool which enables the concurrent design with integrated and balanced design decisions at the initial design stage of injection molding.

• Design & Manufacturing
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• v.13 no.2
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• pp.30-36
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• 2019

Traditional cell culture(2-dimensional) is the method that provide a nutrient and environment on a flat surface to cultivate cells into a single layer. Since the cell characteristics of 2D culture method is different from the characteristics of the cells cultured in the body, attempts to cultivate the cells in an environment similar to the body environment are actively proceeding in the industry, academy, and research institutes. In this study, we will develop a technology to fabricate micro-structures capable of culturing cells on surfaces with various curvatures, surface shapes, and characteristics. In order to fabricate the hemispheric plastic structure(thickness $50{\mu}m$), plastic preform mold (hereinafter as "preform mold") corresponding to the hemisphere was first prepared by injection molding in order to fabricate a two - layer structure to be combined with a flat plastic film. Then, thermoplastic polymer dissolved in an organic solvent was solidified on a preform mold. As a preliminary study, we proposed injection molding conditions that can minimize X/Y/Z axis deflection value. The effects of the following conditions on the preform mold were analyzed through injection molding CAE, [(1) coolant inlet temperature, (2) injection time, (3) packing pressure, (4) volume-pressure (V/P). As a result, the injection molding process conditions (cooling water inlet temperature, injection time, holding pressure condition (V / P conversion point and holding pressure size)) which can minimize the deformation amount of the preform mold were derived through CAE without applying the experimental design method. Also, the derived injection molding process conditions were applied during actual injection molding and the degree of deformation of the formed preform mold was compared with the analysis results. It is expected that plastic film having various shapes in addition to hemispherical shape using the preform mold produced through this study will be useful for the molding preform molding technology and cast molding technology.