| Summary: | 碩士 === 長庚大學 === 機械工程研究所 === 89 === Gas assisted injection molding has become one of the most important methods for the manufacture of plastic products. However, there are several unsolved problems that confound the overall success of this technique. Weldline caused by the flow-lead effect of the polymer melt is one of them. In this report, an L’18 orthogonal array design based on the Taguchi method was conducted to investigate the flow-lead induced weldlines of gas assisted injection molded parts. A plate cavity with a gas channel on the side was used for molding. Experiments were carried out on an 80-ton reciprocating injection molding machine equipped with a high-pressure gas injection unit. After molding, the depth of the weldline was measured. For the factors selected in the main experiments, melt injection temperature and mold temperature were found to be the principal factors affecting the weldline depth of gas assisted injection-molded parts. Experimental investigation of a gas assisted injection molding problem can help in better understanding the weldlines caused by flow-lead effects, so that steps can be taken to optimize the surface quality of molded parts.
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