外部氣體輔助射出成型對補強肋的表面品質之研究

隨著資訊產業的蓬勃發展，對產品設計之多變性、強度及外觀的要求日益提高，傳統射出成型製程已無法因應市場之需求，許多要求高表面品質的產品往往都必須經過二次加工處理，而外部氣體輔助射出成型製程不但可以增大產品設計自由度，還可以有效提高產品表面品質、增加產品強度，非常適合應用於現今的3C產品上；但目前對於此製程研究的相關文獻仍相當缺乏。在本論文中，選用廣為應用於3C產品的ABS塑料，利用一長100㎜、寬50㎜、厚度1.5㎜的平板，在平板上設計四種與產品厚度不同比例的肋，分別為0.6倍、0.8倍、1倍、1.2倍，配合三種不同成型表面，分別為一般拋光表面、鏡面拋光8000表面、咬花TH-114表面，首先針對外部氣體輔助射出成型時，各製程參數對產品表面收縮凹陷深度之影響趨勢；其次，根據前段實驗結果，設計一組外部氣體輔助射出成型最佳化製程參數與傳統射出成型製程做比較，觀察其對產品表面品質改善之最大效益。最後再對兩種製程其產品減重比做比較。研究結果顯示，製程參數以模具溫度、氣體壓力及氣體保壓時間影響產品表面收縮凹陷之趨勢最大，模具溫度升高使的凝固層較薄，有助於提升氣體保壓的效果；而在肋厚較大之區域則需要較大的氣體壓力及較長之氣體保壓時間將熔膠不斷的推擠向模面，達到良好的產品表面品質。在使用外部氣體輔助射出成型最佳化製程參數方面，相較於傳統射出成型製程可大幅減低產品表面收縮凹陷之深度，將一般拋光與鏡面拋光表面之產品收縮凹陷深度分別減少至0.68 μm及0.89 μm以下，透過視覺觀察三種成型表面之產品表面品質，外部氣體輔助射出成型製程可消除產品表面之收縮痕；而在產品減重實驗方面，三種不同的成型表面使用外部氣體輔助射出成型製程能有效的減輕產品重量達1.67 ~ 3.19 %。

關鍵字

凝固層；收縮凹陷；外部氣體輔助射出成型；肋

並列摘要

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%.

並列關鍵字

Rib ； Sink Mark ； Freeze Layer ； External Gas-Assisted Injection Molding

參考文獻

12. L. M. Li, K. K. Lee, K. W. Suen, K. L. Cheng, K. F. Chan, “Technical Handbook for Internal, External and Super Cool Gas-Assisted Injection Moulding Process”, The Hong Kong Productivity Council Publishers.(2006).

15. Li, L. M., Lee, K. K., Suen, K. W., Cheng, K. L., “Technical Handbook for External Gas-Assisted Injection Moulding Process”, The Hong Kong Productivity Council Publishers.(2003).

參考文獻