• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.10a
• /
• pp.223-226
• /
• 2004

It is net easy to predict the shrinkage rate of a plastic injection mold in its design process. The shrinkage rate should be considered as one of the important performances to produce the reliable products. The shrinkage rate can be determined by suing the CAE tools in the design produces. However, since the analysis can take minutes to hours, the high computational costs of performing the analysis limit their use in design optimization. In this study, the surrogate models based on the RSM is used in lien of the original models, facilitating design optimization.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2001.04a
• /
• pp.303-306
• /
• 2001

To shorten the delivery time for new products, a lot of prototype plastic parts manufacturing technologies have been developed including injection molding, vacuum casting, thermal forming and so on. Among them, RIM is becoming one of a important soft tooling methods to produce prototype and mass production parts within short time. Further more, as the rapid prototyping technology based tooling methods are playing an important role in prototype manufacturing industry, the utility of the RIM is increasing. But few analyses and mold design techniques have been developed so far due to its chemical and mechanical complexity during the packing and curing process. This research suggests mold gate design criteria to prevent bobbles from molded parts through simplified mathematical model and change of bubble sizes according to the geometry of the molded parts through experiments. Also this study shows the differences of bobble generation mechanism between RIM and injection molding.

• Journal of the Korean Society for Precision Engineering
• /
• v.8 no.4
• /
• pp.55-63
• /
• 1991

This paper deals with development of a Computer Aided Process Planning System based on knowledge base in addition to database for injection mold as a part of Computer Integrated Manufacturing System for injection mold manufacture. The prposed system consists of four modules such as manufacturing feature code generation module machine tool selection and sequencing module, operation and cutting tool selection mudule and standard time estimation module. The system is programmed by using Turbo Pascal on the IBM-PC/AT. The performance of the system is evaluated by using real problems and the test results indicate that the proposed system is a practical and efficient system.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1997.10a
• /
• pp.716-719
• /
• 1997

This paper describes the runner and gate design capabilities of the RAMEDS system, which is a specialized CAD system for injection mold design, dcvcloped using the application procedure interface of the Unigraphics system. In this system, runners lying on sculptuted partlng surface can be modeled by projecting the runner trajectory on the surface and sweeping a selected cross section along the projcctcd trajectory. In addtion, the system provides solid modeling capabilities for three types of gates currently.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.10a
• /
• pp.474-479
• /
• 2005

Experimental and theoretical studies of internal cavity pressure during injection molding of a spiral tube cavity were carried out. The frozen layer thickness and the evolution of internal cavity pressure were calculated using a commercial software (C-MOLD). The evolution of the internal cavity pressure was recorded during injection molding of polystyrene into a spiral tube mold. To explain the differences observed between the calculated and measured internal cavity pressure, a pressure correction factor (PCF) was introduced based on the plane stress theory. This factor was determined by analyzing the stress state in the melt and calculating the frozen layer thickness near the mold wall. The corrected and experimental pressures have been compared to validate the applicability of the pressure correction factor.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.10a
• /
• pp.657-660
• /
• 2005

It is net easy to predict the shrinkage rate of a plastic injection mold in its design process. The shrinkage rate should be considered as one of the important performances to produce the reliable products. The shrinkage rate can be determined by suing the CAE tools in the design produces. However, since the analysis can take minutes to hours, the high computational costs of performing the analysis limit their use in design optimization. Therefore this study was carried out to presume for mutual relation of analysis condition to get the optimum average shrinkage by regression analysis. The results shown that coefficient of determination of regression equation has a fine reliability over 88.3% and regression equation of average shrinkage is made by regression analysis.

• Journal of the Korean Society for Precision Engineering
• /
• v.12 no.11
• /
• pp.148-158
• /
• 1995

This paper describes a hierarchical structure for feature definition and classification, and feature representation method based on frame structure for process planning of prismatic machined components of injection mold. The concept of Volume Removal Directions and Vertical Faces is proposed to develop a method to define and to classify features for components of injection mold systematically. A method for classifying features by the combination of volume removal directions and vertical faces is developed, and also a feature representation method by using frame structure to represent design and manufacturing information is presented.

• Journal of the Korean Society for Precision Engineering
• /
• v.27 no.1
• /
• pp.105-112
• /
• 2010

Weldlines are generated during the injection molding process when two or more melt flows are brought into contact. The weldlines are unavoidable in the cases of presence of holes or inserts, multi-gated delivery systems, significant thickness change, etc. At the welded contact region, a 'V'-shaped notch is formed on the surface of the molded part. This 'V'-notch deteriorates not only surface appearance but also mechanical strength of the molded part. To eliminate or reduce weldlines so as to improve the weldline strength, the mold temperature at the corresponding weld locations should be maintained higher than the glass transition temperature of the resin material. The present study implements high-frequency induction heating in order to rapidly raise mold surface temperature without a significant increase in cycle time. This induction heating enables to local mold heating so as to eliminate or reduce weldlines in an injection-molded plastic part. The effect of induction heating conditions on the weldline strength and surface appearance of an injection-molded part is investigated.

• Journal of the Korean Society for Precision Engineering
• /
• v.29 no.2
• /
• pp.185-192
• /
• 2012

The paper presents the development of a cooling circuit design system that automatically creates 3D cooling circuit on a given section plane conforming to design specifications, generates 3D solid model of cooling line segments defined on a 2D sketch plane, and verifies interference of 3D cooling channel with the molding die surface. The system was developed mainly for designing plastic injection molding die of vehicular lamp, which helps the mold designer to rapidly construct cooling circuits but also reduce designer's unintended mistakes by conforming to the dimensional design specifications. It is used by an injection molding die manufacturing company in Korea, and reported approximately 20% reduction of cooling channel design time.

• Journal of the Korean Society for Precision Engineering
• /
• v.16 no.4 s.97
• /
• pp.110-115
• /
• 1999

The surface gloss of an injection molded part is one of the most significant point for evaluating the quality of products appearance. The effects of process condition on the gloss of ABS(Acrylonitrile-Butadiene-Styrene) molded part were investigated in this work. The measurements of gloss and morphology on the surface of molded part were carried out with different melt temperature, mold temperature, mold surface roughness, injection pressure and holding pressure. Gloss had a maximum value with melt temperature in the range of 210 to 220 ${^\circ}C$ and with mold temperature 40 to 50${^\circ}C$ and with injection pressure 80~90 MPa, respectively. Melt temperature was shown to have the largest effect on gloss in our work. Gloss was not improved in the region of melt temperature 240${^\circ}C$ above and of mold temperature 60${^\circ}C$ above. It was concluded that the variation of gloss was mainly caused by rubber particles migration under shear stress not by their aggregation or necklace.