• 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).

• Journal of the Korean Society for Precision Engineering
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• v.26 no.3
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• pp.98-102
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• 2009

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 has 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. The filling imbalance was decreased up to result range of $3{\leq}DFI{\leq}8(%)$ by using a new runner system for balanced filling.

• 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.

• Transactions of Materials Processing
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• v.15 no.1 s.82
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• pp.42-46
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• 2006

For mass production, usually injection mold has multi-cavity which is filled through geometrical balanced runner system. Despite geometrical balanced runner system, filling imbalances between cavity to cavity have always been observed. These filling imbalances are one of the most significant factors to affect quality of plastic parts. Filling imbalances are results from non-symmetrical shear rate distribution within melt when it flows through tile runner system. It has been possible to decrease filling imbalance by optimizing processing conditions, but it has not completely eliminated this phenomenon during injection molding processing. This paper presents a solution for these filling imbalances by using Runner Core pin (RC pin). The Runner Core pin which is developed in this study creates a symmetrical shear distribution within runner. As a result of using Runner Core pin, a remarkable improvement in reducing filling imbalances was confirmed.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.2 s.191
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• pp.41-46
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• 2007

Recently, the study for filling imbalance in thermoplastic polymer has gradually been increased. However, it is hard to find the researches for filling imbalance of thermoplastic elastomer(TPE). The experiment of filling imbalance was conducted for the three kinds of thermoplastic vulcanizes(TPVs) in the mold with geometrically balanced runner system. In this experiment, the effects of the melt temperature and injection speed on the filling imbalance were investigated. To solve the filling imbalance, Runner Core pin(RC pin) in the experimental mold was adopted and it's effects was tested. In this paper, we present that the insert length of RC pin is dependent to each polymers for optimal filling balance.

• 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.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.05a
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• pp.39-42
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• 2005

For mass production, usually injection mold has multi-cavity which is filled through geometrical balanced runner system. Despite geometrical balanced runner system, filling imbalances between cavity to cavity have always been observed. These filling imbalances are one of the most significant factors to affect quality of plastic parts when molding plastic parts in multi-cavity injection mold. Filling imbalances are results from non-symmetrical shear rate distribution within melt as it flows through the runner system. It has been possible to decrease filling imbalance by optimizing processing conditions, but it has not completely eliminated this phenomenon during injection molding processing. This paper presents a solution of these filling imbalances through using 'runner core pin'. The runner core pin which is developed in this study creates a symmetrical shear distribution within runner. As a result of using runner core pin, a remarkable improvement in reducing filling imbalance was confirmed.

• The Journal of the Korean dental association
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• v.55 no.5
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• pp.339-350
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• 2017

The aim of the study was to analyze the distribution of dental filling materials for carious permanent teeth of school children in a city. The study was designed as time-serial study, using the data of the dental survey for children aged 8-, 10- and 12-year children living in Gimhae city. The samples were selected by stratified clusters sampling. The number of surveyed samples in depth-analysis for types of dental filling materials were 567 in 2009 and 331 in 2013, respectively. They had dental restorations on one or more teeth. The changing pattern of used dental filling materials was analyzed between 2009 and 2013. Statistical analysis was conducted according to variables related to dental filling material type; DMFT and DMFS index, number of fissure sealed teeth and surface and surveyed year. Amalgam filling rate decreased from 27.9% in 2009 to 18.8% in 2013, while filling rate of tooth-colored materials increased from 56.1% in 2009 and 68.9% in 2013. Amalgam filling rate was a negative correlation with filling rate of tooth-colored materials or gold and number of fissure sealed teeth and a positive correlation with DMFT index. Filling rate of tooth-colored materials was a negative correlation with filling rate of amalgam or gold and DMFT index and a positive correlation with number of fissure sealed teeth. The light-curing composite resin should be included in the reimbursement range of National Health Insurance to solve an inequity of dental health care services.

• Korea-Australia Rheology Journal
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• v.20 no.2
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• pp.79-88
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• 2008

In this study, we focus on the improvement of the filling efficiency in injection molding by application of ultrasonic vibration. While studies about the filling efficiency of typical filling processes in the injection molding have been widely performed, there have been only few studies about the filling efficiency of an ultrasonic process. The effect of the ultrasonic vibration is an important process condition, which influences the flow characteristics of polymer melt. This new condition even affects well-known injection conditions such as cavity pressure, injection temperature and mold temperature. For this study, we carried out a numerical analysis by appropriate modeling and analysis of the ultrasonic process in the filling process. To verify this numerical analysis, we compared the numerical results with the experimental data. Also, we analyzed the filling process in a thin cavity using this numerical analysis. To understand the flow characteristics of polymer melt in the ultrasonic process, we substituted real and complex vibration conditions with simplified and classified conditions according to the position of vibrating cavity surfaces and the phase difference between two opposing cavity surfaces. We also introduced MFR (melt flow ratio) as a new index to estimate the filling efficiency in the ultrasonic process.

• 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.