Molds & Tooling
4 조회수
PP Dimensional Post-shrinkage Drift
문제 현상
PP parts continue shrinking 24~72 hours after demolding, causing precision assembly out of tolerance.
원인 분석
Semi-crystalline PP continues crystallizing and shrinking after demolding (post-crystallization), more obvious in high-temperature environments; inconsistent measurement aging may be misjudged as process fluctuation.
해결 방법
①Extend in-mold cooling for more sufficient crystallization; ②appropriately raise mold temperature to promote in-mold crystallization; ③unify measurement aging (24 hours after molding); ④if necessary, anneal at 60~80℃ for 1 hour to accelerate stabilization.
핵심 요약
PP dimensions should be managed by 'post-aging dimension'.
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