Study on the Surface Improvement of Bubble¬¬-Like Streak for Moistured Plastics by Using Gas Counter Pressure during Injection Moiding

• Main Authors: Chih-Hsun Wang, 汪志勳
• Other Authors: Shia-Chung Chen
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/06790668682383266019

碩士 === 中原大學 === 機械工程研究所 === 104 === Gas counter pressure technology was developed in 1970 and was used in industry since 1980. This technology is to maintain a constant pressure in the mold before injection starts. Plastic pellets contain a certain percentage of vapor. During injection molding the melt was heated to melting temperature, the vapors grow into bubbles and will be flipped to the surface due to fountain flow effect and cause the silver streaks. This study focuses on using GCP to restrict the growth of vapors and avoid the silver streaks under different polymer moisture content. The results show that the silver streaks were affected mainly by the polymer moisture content. Further more GCP can eliminate the silver streaks under highly moisture material. When the GCP raised to 50 bar, the silvery streaks can be eliminated under different moisture content polymer. On the other hand, using vacuum glue to seal the mold is also helpful in reduce the silver streaks.