Study of Mechanical Strength of Weld-line in ABS Injection Molding Parts

• Main Authors: Nan-Tsun Kuo, 郭南村
• Other Authors: Tsyr-Jang Chen
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/65095060059932461611

碩士 === 龍華科技大學 === 機械系碩士班 === 92 === As the trend of getting smaller products becomes more popular, the demand on strength and quality for plastic product has also become more important.The weld -line is the weakness on the strength for injection plastic products, therefore has attracted many researchers’ attentions. This thesis focuses on ABS to discuss how the strength of the weld-line is affected in Thin-wall Injection Molding. ABS is used to inject test pieces of ASTM standard, with and without weld-line, at various injection conditions and thicknesses. Test pieces are put onto ASTM for strength tests. In our study, the model for polymers proposed by Kim and Suh was also modified to establish an empirical correlation for strength with weld-line. This correlation uses the data of tested strength and method of regression analysis to take thickness of test pieces, melt temperature, mold temperature, packing pressure and injection velocity as independent factors. It is expected that this correlation can be used to predict the strength of product with weld-line. ABS has similar trend as other plastic material; that is increase on the melt temperature, mold temperature and injection velocity increase the strength of the test pieces at the weld-line, while the packing pressure has reverse effect. However, it is also found that at different piece thickness, i.e. 0.8mm, 1.0mm, 1.2mm and 2.5mm, weld-line has least strength at 1.0m, but best strength at 0.8mm.