• Journal of the Korean Society for Precision Engineering
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• v.21 no.6
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• pp.117-121
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• 2004

Injection molding is the one of the most important processes for mass production of plastic parts. Usually injection molds for mass production are constituted to multi-cavity runner system to manufacture the more parts at a time. Multi-cavity molds are designed to geometrically balanced runner system to uniformly fill to each cavity. But, when injection molding is performed using a mold with balanced runner system filling imbalances are occurred between the cavity to cavity. The previous studies by Beaumont at. all reported that filling imbalance occurred by thermal unbalance on the mold and viscosity variation of resins and so on. In this study, we conducted experiments in order to know the causes of filling imbalance for 3 plate type mold with 8 cavities. And we exhibited a new so called 4BF mold (4 plate type Balanced Filling Mold) to be possible filling balance. We conducted a experimental injection molding to verify the efficiency of the 4BF mold. In the results of the experiment, we could confirmed the balanced filling possibility of the 4BF mold.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.9 s.174
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• pp.173-178
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• 2005

Recently plastic parts are molded for the purpose of mass production in multi-cavity system. Therefore, designer is usually designing mold that has geometrically balanced runner lay-out for filling balance at each cavity. Although, mold is manufactured with geometrically balanced runner lay-out, there are actually filling imbalances in the cavities. These filling imbalances phenomenon are caused by complicated interaction between melt and mold. In this study, based on previous studies for filling imbalances in cold-runner mold, filling imbalances in hot-runner mold were investigated by CAE and injection molding experiments. ABS and PMMA as amorphous polymer, PA as crystalline polymer were used to compare the filling imbalances. There were different results of CAE and experiment. The filling imbalances decreased as injection rate increased without regard to kind of resins and were lower than the one of cold-runner.

• Design & Manufacturing
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• v.2 no.5
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• pp.25-29
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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 imbalance have been observed. Filling imbalance could be decreased by modifying processing conditions such as injections rate, mold temperature, injection pressure, melt temperature that are related to shear, viscosity. In this study, a series of experiment was conducted to investigate filling imbalance variation when modifying runner layout and ploymer and to determine which processing condition influences as the primary cause of filling imbalance in geometrically balanced runner system. The filling imbalance was desreased up to result range of $3{\leq}DFI{\leq}8(%)$ by using a new runner system for balanced filling.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.598-601
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• 2005

Plastic parts are molded for the purpose of mass production in multi-cavity system. Therefore, designer is usually designing molds that has geometrically balanced runner lay-out for filling balance at each cavities. Although, mold is manufactured with geometrically balanced runner lay-out, there are actually filling imbalances in cavities. These filling imbalances phenomenon are caused by complicated interaction between melt and mold. In this study, based on previous studies for filling imbalances in cold-runner mold, filling imbalances in hot-runner mold were investigated by CAE and injection molding experiments. ABS, PMMA as amorphous polymer and PA, PP as crystalline polymer were used to compare the filling imbalances. The filling imbalances decreased as injection rate increased without regard to kind of resins and were lower than the one of cold-runner.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.752-755
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• 2003

Injection molding is the one of the most important processes for mass production of plastic parts. Usually Injection molds for mass production are constituted to multi-cavity runner system to manufacture the more parts at a time. To uniformly fill to each cavity, multi-cavity molds are designed to geometrically balanced runner system. However. in practice this is not the case. The previous studies by Beaumount at.[2] reported that filling imbalance occurred by thermal unbalance on the mold and viscosity variation of resins and so on. In this study, we conducted experiments in order to know the causes or filling imbalance for 3 plate type mold with 8 cavities. We presented a new so called 4BF mold(4plate Type Balanced Filling Mold) to improve filling balance. We conducted a experimental injection molding to verify a efficiency of the 4BF mold. In the results of the experiment, We could confirmed the possibility of the 4BF 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.

• Transactions of Materials Processing
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• v.15 no.1 s.82
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• pp.47-56
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• 2006

It is well known that the family-mold has an advantage to reduce the cost for production and mold. However, defects are frequently occurred by over packing the smaller volume cavity during molding, especially when the family-mold has a volumetric difference between two cavities. In this study, the cavity-filling imbalance was confirmed by the temperature and the pressure sensors, and a variable-runner system was developed for balancing the cavity-filling. Experiments of balancing the cavity filling was carried out in the family-mold with the variable-runner system, and balancing the cavity-filling was confirmed by changing the cross-sectional area of a runner in the variable-runner system with the temperature and pressure sensors. The influence of the injection speed to the balancing-capability of the variable-runner system was also examined in the experiment.

• Design & Manufacturing
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• v.2 no.3
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• pp.1-5
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• 2008

Plastic parts are molded for the purpose of mass production in injection molding. Therefore designer is usually designing molds that has geometrically balanced hot runner lay-out for filling balance at cavities. Although, mold is manufactured with geometrically balanced runner lay-out, there are actually filling imbalances in cavities. These filling imbalances phenomenon are caused by complicated interaction between melt and mold. In this paper, filling imbalances for internal gear based on injection molding in hot-runner mold were investigated by CAE and injection molding experiences.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.1
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• pp.104-112
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• 1998

The mold filling process has been a central issue in the development of numerical methods to solve the casting processes. A mold filling which is inherently transient free surface fluid flow, is important because the quality of casting highly depends on such phenomenon, Most of the existing numerical schemes to solve mold filling process have severe limitations in time step restrictions or Courant criteria since explicit time integration is used. Therefore, a large computation time is required to analyze casting processes. In this study, the well known SOLA-VOF method has been modified implicitly to simulate the mold filling process. Solutions to example filling problems show that the proposed method is more efficient in computation time than the original SOLA -VOF method.

• Design & Manufacturing
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• v.1 no.1
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• pp.13-16
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• 2007

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 imbalance have been observed. Filling imbalance could be decreased by modifying processing conditions such as injections rate, mold temperature, injection pressure, melt temperature that are related to shear, viscosity. In this study, a series of experiment was conducted to investigate filling imbalance variation when modifying runner layout and polymer and to determine which processing condition influences as the primary cause of filling imbalance in geometrically balanced runner system.