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Quantification of Weld-line and Quantitative Evaluation of its Molding Factors in Injection Molding
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Kuroda, Hideo / Shimohira, Katsuyoshi
A quantitative study of the appearance quality of weld-line which had been previously examined by human eyes was performed. ABS (Acrylonitrile-Butadiene Styrene) dumbbell samples were molded with a weld line in the middle and the weld-line gap depths were measured by a surface roughness measuring instrument. An automatic-search multiple-regression analysis for optimum factors was applied in order to generalize the test results. The results are summarized as follows ;
(1) It became clear that weld-line quality could be quantified by weld-line gap depth.
(2) A reliable equation relating weld-line gap depth, resin viscosity at the weld and cavity pressure was obtained.
(3) The allowable limits of variation in molding factors for producing invisibl weld-lines (below 1.0ƒÊm of weld-line gap depth) were determined using the multiple regression analysis.
Key words: Quantification / Weld-line / Appearance quality / Multiple-regression / ABS / Gap depth / Molding factor