• Design & Manufacturing
• /
• v.12 no.2
• /
• pp.22-26
• /
• 2018

In the automotive industry these days, plastic parts have been developed and replaced with plastic parts by maintaining the same function of existing press parts for a variety of reasons. Injection molding plastic parts are subject to molding defects due to various factors, among which the sink marks usually occur in the areas where bosses and ribs are installed. In this study, we analyzed the influence of various factors on the occurrence of sink marks by using the flow analysis of the forming analysis program(Moldflow analysis) using the rib model with the T-shape. Tests have shown that the greatest influence on the sink mark of cosmetic products is the thickness and pressure of the ribs, and the thickness of the basic moulding thickness of the product increases. However, it was considered that the resin temperature and the mold temperature do not greatly affect the occurrence of the sink mark.

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

• Journal of the Korean Society for Precision Engineering
• /
• v.25 no.9
• /
• pp.38-44
• /
• 2008

Light guide plate is one of most important components which are composed of back light unit, affecting the quality and performance of LCD. Average brightness and uniformity are especially key factors for designing the light guide unit. These qualities are affected and controlled by the pattern being attached to the back of light guide unit. In order to obtain high brightness and uniformity the optimized pattern design is adopted for LGP. In this study, optimized molding condition for LGP with 0.4 mm thickness was obtained by using the Moldflow simulation software and the optimized pattern for better brightness uniformity was designed for the thickness of the 0.4 mm by trial and error method. The brightness was measured for the different LGP thicknesses and the residual stress analysis was performed for 0.4 mmthickness by the photoelasticity and the results are compared with 0.5 mm, 0.6 mm thickness.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.7 no.6
• /
• pp.1040-1046
• /
• 2006

This paper is aimed to investigate the deformation caused by ununiform contraction of injection molding with highly big differences of thickness by the continuity of various curvature radius. By CAE analysis, the uniform cooling structure and optimum molding conditions are found for Jars made of SAN and PMMA materials and applied to the design of chill. In order toevaluate the molding pressure, resin temperature, molding temperature, cooling conditions, Moldflow program is applied. As results of experiments, the deformation and inferiority phenomena in Jars are analyzed for each factor and proposed the injection molding conditions to minimize the cooling structure and reduce the cycle time.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.4
• /
• pp.623-632
• /
• 2018

Predicting the behavior of rheological polymers is highly shear rate- and temperature-dependent. The Cross-WLF viscosity model has become a powerful solution that describes the shear rate- and temperature-dependent characteristics. To estimate the behavior of polymers in computational simulations, the coefficients of the Cross-WLF model should be well identified. An identification technique was proposed to determine the Cross-WLF viscosity model coefficient. The assumption is that the Cross-WLF viscosity model well describes the real characteristics of polymers when the calculated viscosity with the parameters is identical to the reference data. In this study, Auto-desk Moldflow data were used as a reference. The numerical examples showed that the proposed method accurately identifies the Cross-WLF viscosity model coefficients.

• Fibers and Polymers
• /
• v.4 no.2
• /
• pp.89-96
• /
• 2003

A vertebral cage is a hollow medical device which is used in spine forgery. By implanting the cage into the spine column, it is possible to restore disc and relieve pressure on the nerve roots. Most cages have been made of titanium alloys but they detract the biocompatibility. Currently PEEK (polyether ether ketone) if applied to various implants because it has good properties like heat resistance, chemical resistance, strength, and especially biocompatibility. A new shape of vertebral cage is designed and injection molding of PEEK is considered for production. Before injection molding of the cage, it is needed to evaluate process conditions and properties of the final product. Variables affecting the shrinkage of the cage are considered, e.g., injection time, packing pressure, mold temperature, and melt temperature. By using the numerical simula-tion program, MOLDFLOW, several cases are studied. Data files obtained by MOLDFLOW analysis are used for stress anal-ysis with ABAQUS, and shrinkage and residual stress fields are predicted. With these results, optimum process conditions are determined.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.37 no.1
• /
• pp.56-62
• /
• 2024

By introducing curing kinetics and chemo-rheology for the epoxy resin formulation for ultra-high voltage gas insulated switchgear (GIS) Insulating Spacers, a study was conducted to simulate the curing behavior, flow and warpage analysis for optimization of the molding process in automatic pressure gelation. The curing rate equation and chemo-rheology equation were set as fixed values for various factors and other physical property values, and the APG molding process conditions were entered into the Moldflow software to perform optimization numerical simulations of the three-phase insulating spacer. Changes in curing shrinkage according to pack pressure were observed under the optimized process conditions. As a result, it was confirmed that the residence time in the solid state was shortened due to the lowest curing reaction when the curing holding pressure was 3 bar, and the occurrence of deformation due to internal residual stress was minimized.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.25 no.8
• /
• pp.1294-1301
• /
• 2001

In order to reduce the time and cost for assembly, automobile speaker grills have been injection molded with door trims or map pockets in one piece recently. However, several defects such as short shots or air traps can easily occur due to the decreased fluidity of the melting polymer according to the excessive heat transfer to the mold. Therefore, it is necessary to optimize the resin feed system and predict possible defects by CAE analysis. However it is not possible to obtain exact analysis results for the speaker grill by using general shell elements since the heat transfer in the thickness direction which is the dominant factor of the filling stage can not be considered. Therefore, there have been several efforts to simulate the injection molding nature of the speaker grill by using shell elements with an effective thickness which is smaller than the actual thickness of the part. Two empirical values have been recommended for the effective thickness in real practice. One is 50∼70% of the thickness of the speaker grill and another is the gap distance between the adjacent holes. In this paper, CAE analyses of a map pocket with a speaker grill were conducted using shell elements with both of these recommended effective thicknesses, and the predicted flow fronts were compared with the findings from injection molding experiments. The commercial code MOLDFLOW was used for injection molding analysis and an 850 ton injection molding machine was used for experiments.

• Korean Chemical Engineering Research
• /
• v.50 no.2
• /
• pp.264-269
• /
• 2012

Die slide injection marvelously reduces the cost and time in processing plastic products because they can simplify the conventional process through eliminating additional process. However, this process must resolve some defects like whitening, resin infiltration, blowhole, resin overflow, etc. In this study, the process parameters of the injection molding are optimized by using the finite element method and Taguchi method. The injection molding analysis is simulated by employing the Moldflow insight 2010 code and the 2nd injection is by adopting the Multi-stage injection code. The process parameters are optimized by using the $L_{16}$ orthogonal array and smaller-the-better characteristics of the Taguchi method that was used to produce an airtight container (coolant reservoir tank) from polypropylene (PP) plastic material.rodanwhile, the optimum values are confirmed to be similar in 95% confidence and 5% significance level through analysis of variance (ANOVA). rooreover, new products and old products were compared by mdasuring the dimensional accuracy, resulting in the improvement of dimensional stability more than 5%.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2000.05a
• /
• pp.812-815
• /
• 2000

Injection molding process was taken to manufacture DC motor case that surrounds DC motor used as automobile parts. Up to now, DC motor case has been made by the deep drawing process or bending process of metal materials. Simulations of filling, packing and cooling processes were done by CAE tool like Moldflow software. Optimal delivery system was decided from the analysis of flow balance, and packing and cooling analyses were performed by using the design of experiment to minimize the volumetric shrinkage of molded part and the temperature difference between mold and part.