• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 1999.03b
• /
• pp.131.2-135
• /
• 1999

This study focuses on part quality and cycle times under gas-assisted injection molding(GIM) of housing molded parts. The position of the gas channel was estabished near to parting line at the end of last locations to fill. Applied hot runner and valve gates the gas was introduced directly into the mold cavity via gas pin. As GIM was applied the introduced directly into the mold cavity via gas pin. As GIM was applied the conclusion reached as follows. I) The quality of appearance was improved by reducing sink marks and scratches of texture ii) The realibility was improved by preventing warpages and reinforcing rigidity through optimum gas channel layout iii)It is enable to use small size of injection molding machine step by step as GIM was accomplished low pressure and reduced clamp forces against CIM iv)The productivity were improved by reducing cycle times.

• Journal of the Korean Society for Precision Engineering
• /
• v.17 no.10
• /
• pp.102-109
• /
• 2000

In the present study, gas-assisted molding and structural vibration analysis of hollow long cylinder with the variation of gas injection pressure are performed. Though there are so many parameters such as delay time, injection pressure, and gas pressure on gas-assisted molding, the latter has the most dominant effect on this process. Therefore, the present paper deals with the effects of gas pressure on the dynamic stiffness of the model by means of vibration analysis and then suggests the fundamental materials which can be directly adapted to manufacturing lines.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2011.06a
• /
• pp.1193-1194
• /
• 2011

• Transactions of Materials Processing
• /
• v.14 no.5 s.77
• /
• pp.452-459
• /
• 2005

Gas assisted injection molding (GAIM) is an innovative low-pressure injection molding technique that can provide numerous benefits such as reduced part warpage, excellent surface quality without sink marks, low injection pressure and greater design flexibility. However, adoptions of GAIM may cause unexpected defects since it requires many subtle design factors such as resin shot size, delay time and gas injection pressure, which wouldn't be considered in conventional injection molding process. Therefore, experiences applying GAIM should be collected and examined in order to establish design rules of the new technique. The purpose of this paper is to summarize developing cases of three automotive interior parts such as instrument panel, map pocket folding and center facia side panel so that possibilities and limitations of GAIM were examined. As a result, it is necessary to consider characteristics of GAIM at the initial stage of part design in order to obtain various advantages of the GAIM process without occurring severe defects, which would increase time and cost required to the part development.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2003.06a
• /
• pp.852-855
• /
• 2003

Gas-Assisted Injection Molding(GAIM) process, that can be used to provide a hollow shape in a molding, is a variant of the conventional injection molding process. GAIM has many advantages such as reduction of material, sink mark. warpage. and lower injection pressure. Thus, GAIM has been widely applied in the industry to make moldings with a hollow channel such as handles, TV frames and so on. On the other hand, GAIM has some disadvantages such as slow cooling time and flow marks. In the disadvantages, hot gas core causes slow cooling of a molding and the overflow. which is to prevent flow mark. is waste of materials. To solve these problems, we developed a new GAIM system that we called RGIM(Reverse Gas Injection Molding). The RGIM has two special units; one is the overflow buffer, which is used for reduction of a material, and the other tile air unit, which is used for faster cooling of a molding. We conducted an experiment and simulation to verify the efficiency of the RGIM system. Through experiments and simulation, we confirmed the effectively operating of the RGIM system and extracted the optimum process conditions.

• The Korean Journal of Rheology
• /
• v.11 no.2
• /
• pp.153-158
• /
• 1999

An improved method to predict preferred direction of gas in gas assisted injection molding processes is introduced. Resistance of resin flow is defined and this resistance of resin flow is not directly related to the resistance of gas flow. Pressure drop requirement was believed to be proportional to the resistance to gas flow in our previous work. Instead of using the pressure drop requirement, velocity of resin should be compared to predict the gas flow direction. This method predicts the gas flow direction from the knowledge of process variables such as resin flow length, cross section area of cavity, melt temperature, and short shot. A simulation package was used to confirm the method.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2002.02a
• /
• pp.103-108
• /
• 2002

The gas injection molding technique(GIT) is a special injection molding process and has been an established and acknowledged process technique for many years. GIT has proved successful in cases where warpage has to be minimized, sink marks avoided and material input reduced. The classic field of application for GIT, however, is the production of thick-walled, rod shaped parts or hollow articles. Through this application, the handle part for automobile is molded and this part is consequently used as a insert for the additional injection molding process encapsulated with PVC.

• Transactions of Materials Processing
• /
• v.12 no.8
• /
• pp.738-743
• /
• 2003

The major problems of a plastic injection mould can be devided into two kinds, one is in mould another in injected parts. Most of defects of the former comes from mould design, such as, structure and working. The latter are weld line, warpage, sink mark, burning, flow mark, scratching, shading, black hole and so on. Most of problems in injection molding are difficult to find the reason because of complexity. The purpose of this paper is to improve the quality of plastic injection mould and parts with inquiring the counter plan and analizing troubles of the part of Flat TV Front Cover by flow control method and gas-assisted injection moulding. For minimizing defects of the injection moulded parts, computer aided simulation method for injection mould filling was used. Based on these numerical results, the guidelines of mould design and injection processing condition were established. As a result, the improvement of quality, such as minimizing surface defects of injection moulding parts and troubles in mould was achieved.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2003.10a
• /
• pp.201-206
• /
• 2003

Plastic injection mould have two kinds of trouble, one is in mould another in injection parts. Most of defects of the former take the cause in a design like in structure and working, the later weld line, transforming, sink mark, burning, flow mark, scratching, shading, black hole and so on. Most of problems of the later is difficult for making a clear definitely the reason of defects because of complexible. The purpose of this paper is to improve the quality of plastic injection mould and parts with inquiring the counter plan and rouble of the part of Flat TV Front Cover by flow control method and gas- assisted injection moulding. For minimizing defects from injection moulding parts, this paper was investigated with using computer aided injection mold filling simulations. Based on these numerical results, I established guidelines mould design and injection processing condition. As a results I got the improve of quality, minimizing surface defects moulded parts and troubles in mould.

• Proceedings of the Korean Society of Rheology Conference
• /
• 2003.05a
• /
• pp.147-150
• /
• 2003

No Abstract, See Full Text