• IE interfaces
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• v.9 no.1
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• pp.13-24
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• 1996

Quality of injection molded parts is dependent on both mold design and processing conditions. From the mold design point of view, an optimal shrinkage should be used to compensate the shrinkage of molded parts. From the processing point of view, it is important to analyze the priority of processing conditions because a number processing conditions affect the quality of molded parts. Processing analysis employing the design of experiment was performed, and the shrinkage of molded part was considered as a characteristic parameter to improve the quality. As the result of the analysis of variance on SN ratio of a characteristic value, injection speed and bolding pressure were selected as two effective process parameters. Regression analysis on shrinkage and processing conditions was carried out, and an optimal processing condition was obtained by the response surface analysis. Shrinkage at the optimal condition could be used to reduce the number of try-cut at the step of mold making. The ranges of indirect control parameter, such as maximum cavity pressure or weight, measured at the optimal processing condition were used for monitoring the quality of molded parts in process.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.8 s.179
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• pp.1968-1799
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• 2000

A warpage analysis program has been developed for fiber-reinforced injection molded parts. The warpage is predicted from the residual stress and anisotropic thermo-mechanical properties coupled with fiber orientation in the integrated injection molding simulation. A simple elastic model is used for the calculation of thermally and pressure-induced residual stresses which are employed as the initial conditions in the structural analysis. To improve the reliability of warpage analysis, a new triangular flat shell element superimposing well-known efficient plate bending and membrane element is presented. The numerical examples address the necessity to use anisotropic models for fiber-reinforced materials and show that predicted warpage is in good agreement with experimentally measured one.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.745-750
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• 2000

A warpage analysis program has been developed for fiber-reinforced injection molded parts. The warpage is Predicted from the residual stress and anisotropic thermo-mechanical properties coupled with fiber orientation in the integrated injection molding simulation. A simple elastic model is used for the calculation of thermally and pressure-induced residual stresses which are employed as the initial conditions in the structural analysis. To improve the reliability of warpage analysis, a new triangular flat shell element superimposing well-known efficient plate bending and membrane element is presented. The numerical examples address the neccesity to use anisotropic models for fiber-reinforced materials and show that predicted warpage is in good agreement with experimentally measured one.

• Design & Manufacturing
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• v.11 no.3
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• pp.25-28
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• 2017

The production of carbon fiber reinforced thermoplastics(CFRTP) parts using an injection/compression molding process that differs from the conventionally used fabrication methods was investigated Before the application of composite molding in the injection/compression molding process, a simple compression molding experiment was performed using a hydraulic press machine to determine the characteristics of resin impregnation and to obtain a basic physical property data for the CFRTP. Based on these results, injection/compression molded specimens were manufactured and an additional insert/over molding process was applied to improve the impregnation rate of the molded specimens. The results demonstrated that the tensile strength of the molded parts using the faster injection/compression process was similar to that of a hydraulic press molded product.

• Proceedings of the KSME Conference
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• 2001.06c
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• pp.621-626
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• 2001

Microcellular foaming process was developed at MIT in 1980's to save a quantity of raw materials and improve mechanical properties. There are many process variables in appling microcellular foaming process to the conventional injection molding process. Of all process variables, part dimension control and shrinkage are the most influential on the post molded dimension. The post molding dimensional change of thermoplastic resins is important to tool designers for predicting the specific difference of molded part vs. actual mold cavity. Generally, articles injection molded are smaller in size than the cavity; hence, the term shrinkage factor is used to define the allowance a designer specifies. It is important to consider the factors that influence molded part dimension. According to ASTM Designation: D 955, shrinkage from mold dimensions of molded plastics was measured. In injection molding, the difference between the dimensions of the mold and of the molded article produced therein from a given material may vary according to the design and operation of the mold. In this paper, shrinkage data of molded plastic parts was obtained. It can be an important information for designing optimum mold system in a microcellular foaming injection molding process.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.6
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• pp.110-116
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• 1994

In this research, the tensile strength of molded parts and pressure distribution were analyzed to study the cavity filling stage and packing stage in injection molding. The measurement of cavity pressure was obtained by a data acquisition system with the installation of transducers in the cavity. Molded parts were tested by a universal testing machine to obtain the tensile strength. For the experimental work, the tensile strength of molded parts increased with longer packing time and exact freezing time of the gate was obtained by a cavity pressure curve. In addition, the effect of packing did not occur and tensile strength was almost constant after early 1.5 sec of the freezing time of gate. Density tended to be higher about 0.2% due to a larger degree of mold temperature and melt temperature. Also, changing pressure in the cavity was effectively sensed. Thereafter, the possibility of the development of pattern recognition expert system was confirmed on the basis of the experimental results.

• Journal of the Korean Ceramic Society
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• v.35 no.6
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• pp.635-639
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• 1998

When the low pressure injection molded parts are debinded by wicking and subsequent thermal pyrolysis the optimum transition point from wicking to thermal pyrolysis is just after the completion of the constant wicking rate period. Even when the partially debinded parts were heated at 5$^{\circ}C$/min after reaching the 1st falling rate period the debinding defects such as distortion and cracks were not found.

• Design & Manufacturing
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• v.13 no.2
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• pp.12-16
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• 2019

For optimal injection molding, various molding conditions should be combined well. Therefore, engineers should be thoroughly familiar with mold design, fabrication, and injection molding. The choice of resin among the various molding conditions is closely related to the productivity of the molded part and the deformation after molding, so the engineer must select the appropriate resin. Engineers work on the basis of data provided by resin manufacturers during molding. However, in actual molding work, it is necessary to apply values slightly different from those provided to obtain molded articles of desired performance. In this study, various deformations of molded products were compared with respect to crystalline resin and amorphous resin when molded according to the data provided by the resin maker and molded at the changed values at the work site.

• Journal of the Korea Institute of Military Science and Technology
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• v.15 no.3
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• pp.231-240
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• 2012

During the past two decades, Metal Injection Molding(MIM) has become a very competitive technology to fabricate small, precise and complex-shaped parts in large quantities. In this research, the applicability of MIM technology in the mass-production of the high precision fuze parts to save manufacturing cost was investigated. The water-atomized 17-4PH stainless steel powder, one of the best corrosion-resistant high strength materials, was injection-molded into real-shape fuze part and flat tensile specimens. The injection-molded parts were thermally debound in hydrogen gas flow without solvent extraction. Sintering of the debound parts was carried out in vacuum at temperatures ranging from $1150^{\circ}C$ to $1370^{\circ}C$. The sintering behavior, mechanical properties, dimensional precision, corrosion resistance of the MIMed 17-4PH stainless parts were investigated. It was found that almost all the properties of the MIMed parts were comparable to those of the mechanically machined parts. Also, actual military field tests using both MIMed and mechanically machined fuze parts were performed as well and were found to be very successful.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.1
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• pp.66-72
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• 2011

Injection pressure is an important factor in filling procedure for injection molded parts. In addition, weldlines should be avoided to successfully produce injection molded parts. In this study, we optimally obtained injection molding process parameters that minimize injection pressure. Then, we determined the thickness of the part to avoid weldlines. To solve the optimization problem proposed, we employed MAPS-3D (Mold Analysis and Plastics Solution-3 Dimension), a commercial CAE tool for injection molding analysis, and PIAnO (Process Integration, Automation, and Optimization) as a commercial PIDO (Process Integration and Design Optimization) tool. We integrated MAPS-3D into PIAnO, automated the analysis and design procedure, and performed optimization by employing PQRSM (Progressive Quadratic Response Surface Method) equipped in PIAnO. We successfully obtained optimization results, which demonstrates the effectiveness of our design method.