Study on the Part Surface Quality of Rib with External Gas-Assisted Injection Molding

• Main Authors: Chien-Chia Su, 蘇建嘉
• Other Authors: Shia-Chung Chen
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/13594848234016453853

碩士 === 中原大學 === 機械工程研究所 === 95 === Accompanying with the I.T. industry develops vigorously; more and more people ask for stylish design, strength quality and good looking of products. Traditional Injection Molding Process can’t afford the desire of the market, and most high quality products need to be reprocessed. Therefore, External Gas-Assisted Injection Molding not only can enhance Part Surface Quality and strength but also make design flexible and variety. It applied to 3C products fittingly nowaday, but there still has short of relative references of the process. Following the thesis, we would study on the ABS material which widely applied in 3C products; by using a flat that length 100mm, width 50mm and thickness 1.5mm and design four different products with different proportion of ribs. The rib each is 0.6, 0.8, 1 and 1.2 times with three different part surfaces which are surface polishing, 8000 mirror polishing and TH-114 etching. When investigating External Gas-Assisted Injection Molding; first, we found out the shrinkage depth depends on the process parameter of the products. Second, according to the result of the experiments; we develop an External Gas-Assisted Injection Molding with the best process parameter and compare with the traditional Injection Molding Process, which in order to observe the best benefit of improving products’ appearance. At last, compare the two processes’ reduce part weight ratio. According to the research, the temperature, gas pressure and gas packing time of process parameter influence most to products’ shrinkage depth. Higher temperature of molding causes thinner freeze layer and that helps rising gas packing time effective. Meanwhile, the depth rib area needs more gas pressure and longer gas packing time that makes melt push forward to the surface continually and reach to better quality. At using External Gas-Assisted Injection Molding in best process parameter; in comparison with traditional Injection Molding Process, it can decrease the shrinkage depth of surface. During the general polishing we decrease to 0.68mm and mirror polishing decreased under 0.89 μm. By eye-investigating on the surface quality of the three different products, the one using External Gas-Assisted Injection Molding can remove sink marks. As mention to the experiment of reduces part weight; three different molding surfaces which use External Gas-Assisted Injection Molding could reduce products, gravity effectively from 1.67% to 3.19%.