• Polymer(Korea)
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• v.32 no.6
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• pp.501-508
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• 2008

Small injection molded articles such as lens and mobile product parts are usually molded in multi-cavity mold. The problem occurring in multi-cavity molding is flow unbalance among the cavities. The flow unbalance affects the dimensions and physical properties of molded articles. First of all, the origin of flow unbalance is geometrical unbalance of the delivery system. However, even the geometry of the delivery system is well balanced, cavity unbalance occurs. This comes from the temperature distributions in the cross-section of runner. Temperature distribution depends upon injection speed because heat generation near runner wall is high at high injection speed. Among the operational conditions, injection speed is the most significant process variable affecting the filling unbalances in multi-cavity injection molding. In this study, experimental study of flow unbalance has been conducted for various injection speeds and materials. Also, the filling unbalances were compared with CAE results. The dimensions and weights of multi-cavity molded parts were examined. The results showed that the filling unbalances vary according to the injection speeds and resins. Subsequently, the unbalanced filling and pressure distribution in the multi-cavity affect the dimensions and physical states of molded parts.

• Design & Manufacturing
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• v.6 no.2
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• pp.74-78
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• 2012

A multi-cavity injection mold system of protein chip for point-of-care with cavity temperature and pressure sensors was proposed in this work. In advance of manufacturing for the multi-cavity injection mold system, a single cavity injection mold system to mold protein chip was considered. Injection molding analysis for the presented system was performed to optimize the process of the molding and suggest guides to design. On the basis of the results for the single cavity system, a multi-cavity injection mold system for protein chip was analyzed, designed and manufactured with cavity temperature and pressure sensors. Results of balanced filling for protein chip models were obtained from the presented mold system.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.05a
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• pp.381-388
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• 2003

The paper presents our study of development for multi-cavity preform mold system which consists of hot runner system and valve gate. For this purpose, stretching blow molding process and preform injection process were simulated by Polyflow and Moldflow. Based on various results of the preform injection process analysis, process planning was established. The sectional thickness distribution of preform was optimized. Preform injection mold system was designed by these technical analysis data. Finally, 24-cavity preform mold system was successfully developed.

• 한국금형공학회:학술대회논문집
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• 2008.06a
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• pp.155-158
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• 2008

Flow imbalance among the cavities was often observed in multi-cavity mold. The flow imbalance affects on the dimensions and physical properties of molded articles. First of all, the origin of flow imbalance is geometrical imbalance of delivery system. However, even the geometry of delivery system is balanced the cavity imbalance is being developed. This comes from the temperature distribution in the cross-section of runner, which is affected by the operational conditions. In this study, experimental study of flow imbalance has been conducted for various injection speeds. This study also suggests new runner design to eliminate flow imbalance in multi-cavity injection mold. Simulation and experimental results showed suggested new designed runner could eliminate or reduce flow imbalance in multi-cavity injection mold.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.444-447
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• 2008

Recently, the need of thin-walled injection molding and enhancement of its productivity is greatly increased. In this study, we designed and manufactured a injection molding system, which can mold a part with the thickness of $500{\mu}m$ and 8 cavity. And processing technique for the multi-cavity injection molding system, which is capable of mass productivity on the plastic parts, was considered. The problems of unbalance/imbalance on the molding process for the multi-cavity mold were predicted by numerical analysis using plastic injection molding commercial code. In addition, controllable system of melt front filling was introduced for a balanced filling using the mold temperature sensor on injection mold. It was shown that balanced filling with the suggested injection molding system was possible for $500{\mu}m$ plastic parts with 8 cavity layout.

• Journal of the Korean Solar Energy Society
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• v.25 no.2
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• pp.53-62
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• 2005

In this study, the thermal performance of multi-story double-skin facade(DSF) with variation of cavity height is evaluated to offer useful data in determining cavity height of multi-story DSF. For this, thermal criteria for multi-story DSF is adopted and a DSF model for evaluation of the thermal performance is established. Through the evaluation of CFD simulation, the recommended height of multi-story DSF is 5 stories or less to improve the thermal performance during the intermediate season.

• Design & Manufacturing
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• v.2 no.5
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• pp.16-20
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• 2008

Almost all injection molds have multi-cavity runner system for mass production, which are designed with geometrically balanced runner system in order to accomplish filling balance between cavity to cavity during processing; However, even though geometrically balanced runner is used, filling imbalances have been observed. In these day, the CAE has been used widely in injection molding. However, CAE with fusion mesh can't indicate such as jetting, flow mark and filling imbalance in multi cavity mold. In this study, we investigated the filling imbalance according to runner shapes by CAE analysis. As a result in CAE, in case of binary branch runner system, filling imbalance was indicated between cavity to cavity, but the flow pattern of each cavity uniformed in unary branch runner system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.5
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• pp.1552-1557
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• 2010

The cylindrical gear in power window motor assembly is important to doors of automobile. This study is performed for the purpose of getting a manufacturing technique instead of large quantities import and six-cavity mold production. This multi-cavity cylindrical gear is produced under five procedures. The first, mold design of mass-production, the second, making a CAE model for mass-production, the third, manufacturing of sample mold, the fourth, trying-out and measuring of 3 dimensional design, the fifth, acquisition of data analysis and mold modification. Among them, analysis of mass-production using CAE, designing and manufacturing of multi-cavity are successfully performed. In the results, it is concluded that the mold for one gate and eight-cavity based on hot-runner is suitable for making a cylindrical gear.

• Design & Manufacturing
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• v.7 no.1
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• pp.1-6
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• 2013

The injection molding process is a predominant method for producing plastic parts. In order to maximize productivity and molding quality in a injection mold, it is important that each cavity in a multi-cavity injection mold is identical. This requires that cavity dimensions should be identical and delivery system of melt to each cavity have to be the same. Despite the geometrically balanced layout in multi-cavity injection mold more than 4 cavities, it has been observed that the filling in each cavity results in imbalances. Most of cases, this phenomenon of filling imbalances have a bad effect on dimension accuracy, warpage, molding appearance and strength of molding parts. In this study, experiment were conducted to investigate the effect of filling imbalances on the molding quality(surface gloss, shrinkage, tensile strength) in the multy-cavity injection mold.

• 한국금형공학회:학술대회논문집
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• 2008.06a
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• pp.89-94
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• 2008

The injection molding process is a predominant method for producing plastic parts. In order to maximize productivity and molding quality in a injection mold, it is important that each cavity in a multi-cavity injection mold is identical. This requires that cavity dimensions should be identical and delivery system of melt to each cavity have to be the same. Despite the geometrically balanced layout in multi-cavity injection mold more than 4 cavities, it has been observed that the filling in each cavity results in imbalances. Most of cases, this phenomenon of filling imbalances have a bad effect on dimension accuracy, warpage, molding appearance and strength of molding parts. In this study, experiment were conducted to investigate the effect of filling imbalances on the molding quality(surface gloss, shrinkage, tensile strength) in the multy-cavity injection mold.