| Summary: | 碩士 === 中原大學 === 機械工程研究所 === 93 === Abstract
In an era of this 3C generation, the consumer’s demands for the product quality of appearance, security and comfort ability have already reached a limit. Therefore, plastic products with the injection mold industry become more and more important. However, the weld line often causes defects in plastic products. This study mainly concentrates upon practical countermeasures for the weld line. Through this study, it is expected to improve and further resolve the problems caused by the weld line.
This study is to utilize the comparatively analytical approach with reference to the theoretical polymer strength of weld-line model, proposed by Kim & Suh, and do some countermeasure and verification with more than 30 real case studies, the CAE is used to mold flow analysis. At last, two similar molds were compared and verified.
The main countermeasure in this study is to add the thickness of the plastic product. It functions to reduce the obstruction of the flow front, to improve the temperature of the flow joint of melted polymer, to improve the runner system for time controlling of polymer into the mold cavity, consequently to improve the air trap condition in mold cavity, and further to avoid the melted polymer joint’s angle too small.
The study shows that the computational simulated results are quite agreement with the real cases. It can be concluded the polymer molecules can fulfill the totally free diffusion among joint boundaries and perfect bonding by preventing the melt flow from diverging and its joint angle too small, elevating joint’s temperature, and/or keeping air trap from the melt joint. As a consequence, the weld line will not occur.
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