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https://tkuir.lib.tku.edu.tw/dspace/handle/987654321/126430
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| Title: | Impact of Runner Size, Gate Size, Polymer Viscosity, and Molding Process on Filling Imbalance in Geometrically Balanced Multi-Cavity Injection Molding |
| Authors: | Huang, Chao-tsai |
| Keywords: | filling imbalance;multi-cavity;microcellular injection molding;polymer;composites;shear rate |
| Date: | 2024-10-11 |
| Issue Date: | 2024-10-23 12:05:17 (UTC+8) |
| Publisher: | MPDI |
| Abstract: | The injection molding process is one of the most widely used methods for polymer processing
in mass production. Three critical factors in this process include the type of polymer, injection
molding machines, and processing molds. Polypropylene (PP) is a widely used semi-crystalline
polymer due to its favorable flow characteristics, including a high melt flow index and the absence
of a need for a mold temperature controller. Additionally, PP exhibits good elongation and toughness,
making it suitable for applications such as box hinges. However, its tensile strength is a limitation;
thus, glass fiber is added to enhance this property. It is important to note that the incorporation
of glass fiber increases the viscosity of PP. Multi-cavity molds are commonly employed to
achieve cost-effective and efficient mass production. The filling challenges associated with geometrically
balanced layouts are well documented in the literature. These issues arise due to the varying
shear rates of the melt in the runner. High shear rate melts lead to high melt temperatures, which
decrease melt viscosity and facilitate easier flow. Consequently, this results in an imbalanced filling
phenomenon. This study examines the impact of runner size, gate size, polymer viscosity, and
molding process on the filling imbalanced problem in multi-cavity injection molds. Tensile bar injection
molding was performed using conventional injection molding (CIM) and microcellular injection
molding (MIM) techniques. The tensile properties of the imbalanced multi-cavity molds
were analyzed. Flow length within the cavity served as an indicator of the filling imbalance. Additionally,
computer simulations were conducted to assess the shear rate’s effect on the runner’s melt
temperature. The results indicated that small runner and gate sizes exacerbate the filling imbalance.
Conversely, glass fiber-filled polymer composites also contribute to increased filling imbalance.
However, foamed polymers can mitigate the filling imbalance phenomenon. |
| Relation: | Polymers 16, 2874 |
| DOI: | 10.3390/polym16202874 |
| Appears in Collections: | [化學工程與材料工程學系暨研究所] 期刊論文
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