• Design & Manufacturing
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• v.2 no.6
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• pp.33-37
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• 2008

Almost all injection molds have multi-cavity, which are designed with geometrically balanced runner system in order to made filling balance between cavity to cavity during injection molding. However, filling imbalance has been existed in the geometrically balanced runner system. In this study, we made an experiment and investigated that are filling balanced according to material. Also, in case of filling imbalance was occurred, we conducted experiments in order to find out difference of cavity pressure with cavity pressure sensor. When filling imbalance was occurred between cavity to cavity, we investigated the filling imbalance and pressure differences by computer-aided engineering(CAE).

• 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.

• 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.

• 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.

• Design & Manufacturing
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• v.9 no.1
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• pp.23-26
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• 2015

For mass production of plastics, injection molds have multi-cavities. However, filling imbalance between cavity to cavity always has occurred in multi-cavities mold, and this has caused low quality of plastics part. In this study, the closed-loop-control system which can control temperature of hot manifold and nozzle in hot runner mold for filling balance has been suggested, and a series of experiment about difference of filling time and weight in cavity-to-cavity was conducted. As a result of using closed-loop-control system, a remarkable improvement in reducing filling imbalance was confirmed.

• Design & Manufacturing
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• v.7 no.1
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• pp.19-22
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• 2013

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. So, many studies for improving filling balance in the multi-cavities molds are worked up. In this study, the Melt-Buffer which is a new runner system for filling balance has been suggested, and a series of experiment about degree of filling balance in cavity-to-cavity was conducted in the mold with the Melt-Buffer. From the experiment, the filling balance was increased up to 5~6% by using the Melt-Buffer.

• 한국금형공학회:학술대회논문집
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• 2008.06a
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• pp.95-98
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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. So, many studies for improving filling balance in the multi-cavities molds are worked up. In this study, the Melt-Buffer which is a new runner system for filling balance has been suggested, and a series of experiment about degree of filling balance in cavity-to-cavity was conducted in the mold with the Melt-Buffer. From the experiment, the filling balance was increased up to $5^{\sim}6%$ by using the Melt-Buffer.

• Design & Manufacturing
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• v.17 no.4
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• pp.57-62
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• 2023

As a representative method for mass production, a multi-cavity type mold capable of simultaneously molding products of the same shape can be applied. It has the advantage of improving the productivity from several times to several tens of times, but it may cause disadvantages which is the quality deviation with each cavity. This study, therefore, has tried to increase the cavity filling balance by using a melt flipper and a flow distance control part in the runner part of the mold. Along with this, the design and manufacturing of air vents during injection molding have been verified through experimental methods to achieve a higher level of multi-cavity filling balance and dimensional accuracy.

• 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.