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http://dx.doi.org/10.5228/KSPP.2004.13.6.515

Investigation of the Part Shrinkage in Injection Molding for Class Fiber Reinforced Thermoplastics  

Mo J.-H. (서울산업대학교 대학원)
Lyu M.-Y. (서울산업대학교 금형설계학과)
Publication Information
Transactions of Materials Processing / v.13, no.6, 2004 , pp. 515-521 More about this Journal
Abstract
The shrinkages of injection molded parts are different in molding operational conditions and mold design. It also differs from resins. The shrinkages of injection molded parts fur PBT (polybutylene terephthalate), PC (polycarbonate), and glass reinforced PBT and PC have been studied for various operational conditions of injection molding. The part shrinkage of crystalline polymer, PBT was higher than that of amorphous polymer, PC by about two times. The part shrinkages of both polymers decreased as glass fiber content increases. Higher injection temperature and lower injection pressure resulted in a higher shrinkage in both PBT and PC resins. As mold temperature increases the part shrinkage of PC decreased. However, the part shrinkage of PBT increased as mold temperature increases. The part shrinkages of PBT and PC resins decreased as gate size increases since the pressure delivery is mush easier for a larger gate size. The part shrinkage of flow direction was less than that of the perpendicular direction to the flow for both pure and glass fiber reinforced resins. The part shrinkage at the position close to the gate was less than that of the position far from the gate.
Keywords
Injection Molding; Part Shrinkage; Injection Temperature; Mold Temperature; Injection pressure; Glass Fiber; Reinforced Resin;
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