• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.6
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• pp.1478-1485
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• 1993

A shape optimization problem is formulated to determine the optimal position of heating lines in a compression molding die. The objective of the problem is that the cavity surface would be maintained by a prescribed uniform temperature. A boundary integral equation for the sensitivity of the temperature in terms of hole position is derived using the method of shape design sensitivity analysis. The boundary element method is employed to analyze the temperature and sensitivity field of the die. The sensitivity calculation algorithm is incorporated in an optimization routine. To demonstrate a numerical implementation, an example problem arising in thermal design of a compression molding die is dealt with, showing that the number of heating lines chosen for the die strongly affects the ultimate uniformity of the cavity surface temperature.

• Composites Research
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• v.34 no.5
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• pp.269-276
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• 2021

PCM (Prepreg Compression Molding) process is a high-speed molding technology that can manufacture high-quality CFRP (Carbon Fiber Reinforced Plastic) parts. Compared to the autoclave process, it generates less waste and can significantly reduce cycle time, so various studies are being conducted in the aerospace and automobile industries. In this study, in order to improve the quality of the PCM process, a molding method was developed to increase the compression pressure of the press step by step according to the curing behavior of the prepreg. It was confirmed that this multi-stage compression molding technology is a good means to produce high-quality CFRP products and shorten cycle times. And, the laminated prepreg at room temperature was immediately put into the mold and preheated and molded at the same time, so that it could be molded without a separate preheating process. In addition, as a result of applying the same process conditions optimized for flat plate molding to three-dimensional shapes, a product similar to a flat plate in appearance could be made without the process of establishing process conditions.

• Current Applied Physics
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• v.18 no.11
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• pp.1451-1457
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• 2018

Injection compression molding (ICM) is an advantageous processing method for producing thin and large polymeric parts in a robust manner. In the current study, we employed the ICM process for an energy-related application, i.e., thin and large polymeric battery case. A mold for manufacturing the battery case was fabricated using injection molding. The filling behavior of molten polymer in the mold cavity was investigated experimentally. To provide an in-depth understanding of the ICM process, ICM and normal injection molding processes were compared numerically. It was found that the ICM had a relatively low filling pressure, which resulted in reduced shrinkage and warpage of the final products. Effect of the parting line gap on the ICM characteristics, such as filling pressure, clamping force, filling time, volumetric shrinkage, and warpage, was analyzed via numerical simulation. The smaller gap in the ICM parting line led to the better dimensional stability in the finished product. The ICM sample using a 0.1 mm gap showed a 76% reduction in the dimensional deflection compared with the normal injection molded part.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.543-547
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• 2004

The molding characteristics of large-sized orthogonal stiffened plastic plates were investigated in the present study. Models with the geometry of 1800$\times$600$\times$12mm and 1200$\times$600$\times$12mm were designed for injection molding(IM) and injection-compression molding(ICM), respectively. To determine a mold system and reduce the warpage of the presented model after molding process, IM and ICM analyses using MOLDFLOW$^{TM}$ were performed. Also, the experiments were performed to verify the suggested mold system. It was shown that the change of molding method could significant effect on the warpage of designed model.l.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.6
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• pp.133-138
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• 2017

Recently, CFRP composites are widely used as lightweight materials have with excellent mechanical properties and can beare widely used in various fields. In general, thermosetting resins are used for CFRP. However, in recent years, studies have been carried out using thermoplastic resins have been actively carried out to overcome the disadvantages of thermosetting resins. The LFT-D system is a molding method in which a fiber is directly cut to a the desired length while being impregnated with a thermoplastic resin to produce a compound and that is then press-molding molded to form the product. In this paper, before the production of the trailing arm, the compression molding analysis was carried out in order to grasp the problems that may occur during production. Through cCompression molding analysis was applied to calculate of the minimum press pressure and to compare and analysis analyze the molding conditions characteristic required to formfor forming the trailing arm.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.1
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• pp.163-168
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• 1991

During Compression molding of polymeric composite materials, the flow characteristics should be obtained. Understanding the flow states may be useful for determination of optimum molding conditions, charge pattern etc. So far, for obtaining the flow analysis, no-slip boundary condition was applied on the mold surface. However, The study under consideration of the slip was conducted by Barone and Caulk. They have introduced the nondimensional parameter which is the ratio of viscous to friction resistance and governs the frictional condition. But the method for determining the parameter could not be proposed. In our work, the parameter which explains the interfacial friction is measured under a variety of molding conditions. Two-dimensional rectangular part and circular hollow disk are simulated with the measured parameter using the finite element method. Effects of the parameter on shapes of flow fronts are also presented.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.1
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• pp.154-163
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• 1997

Thermally-induced deformation in SMC(Sheet Molding Compound) products is analyzed using three dimensional finite element method. Planar fiber orientation, which causes the anisotropic material properties, is calculated through the flow analysis during the compression stage of the mold. Also curing process is analyzed to predict temperature profile which has significant effects on warpage of SMC products. Through the developed procedure, effects of various process conditions such as charge location, mold temperature, fiber contents, and fiber orientations on deformation of final products are studied. and processing strategies are proposed to reduce the warpage and the shrinkage.

• Transactions of Materials Processing
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• v.20 no.1
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• pp.5-10
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• 2011

The main objective of the present study is to predict the process window of injection-compression molding corresponding to the capability of an injection machine for fabricating 7 inch LGP. The open distance and volume filled after injection stage were found to be two important factors that affect critical requirements such as flow length, injection pressure and clamping force for the process. Process window for the key factors was also predicted by response surface method. As a result, predicted process window for open distance and volume filled after injection stage satisfying the critical requirement with a given injection machine was in the range of 60 ~ 75%, and 104.00 ~ 104.25%, respectively.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2000.04a
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• pp.167-170
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• 2000

Recently the sub-micron structured substrates of 0.74 ${mu}ell$ track pitch and 800 $\AA$groove depth are required for DVD-RAM and the track pitch is expected to be narrower as the need for the information storage density is getting higher. For the accurate replication of the land-groove structure in the stamper to the plastic substrates it is important to control the injection -compression molding process such that the integrity of the replication for the land-groove structure is maximized. in the present study polycarbonate substrates were fabricated by injection comression molding and the land-groove structure regarded as one of mold temperature and the compression pressure on the integrity of the replication were examined experimentally. An efficient design methodology using the response surface method (RSM) the central composite design(CCD) technique and the analysis-of-variance (ANOVA) was developed to obtain the optimum processing conditions which maximize the integrity of the replication with a limited number of experiments.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.333-334
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• 2002

Injection-compression molding parts are many cases with complicated boundary condition which is difficult to analysis of mold characteristics precisely. In this study, the effects of various process parameters such as multi-point gate location, initial charge volume, injection time and pressure have been investigated using finite element method to fomulate the melt front advancement during the mold filling process. A general governing equation for tracking the filling process during injection-compression molding is applied to volume of fluid method. To verify the results of present analysis, they are compared with those of the other paper. The results show a strong effect of processing conditions as a result of variations in the three-dimensional complex geometry model.