Investigation of Flow and Sink Initiation Process in Mold Shapes in Injection Molding
Tetsushi Kaburagi*, Masashi Kurose**, Takahiro Ogawa***,
Hiroki Kuroiwa*, and Tomoyuki Iwasawa*
*Gunma Industrial Technology Center, 884-1 Kamesato-machi, Maebashi, Gunma 379-2147, Japan
**Institute of National College of Technology, Gunma, 580 Toriba-machi, Maebashi, Gunma 371-8530, Japan
***Yamaguchi Co., Ltd., 2309-25 Kamiuekihon-machi, Isesaki, Gunma 372-0013, Japan
Injection molding has faults, or sinks, caused by the shrinkage ofmaterials. Sinks should be inhibited since they greatly affect the dimensions of moldings. In this study, a mold that allows visual observation is employed, and the sink initiation process is analyzed and predicted based on the results of that analysis. This mold has two sections, one flat and one curved. The difference between the deformations in the flat and curved sections is investigated. Methods of inhibiting sinks are considered from the results of the analysis and injection molding experiments. Packing pressure is found to have a great effect on sinks.
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