Molding Process
7 조회수
PVA extruded film thick at edges and thin in the middle
문제 현상
PVA extruded film edges 20-30% thicker than the middle, thickness showing a U-shaped distribution
원인 분석
Improper die flow channel design, low resistance and large flow at edges; PVA melt elasticity swells more at edges; air ring cooling has different effects at edges
해결 방법
1) Die adopts coat-hanger design to balance resistance between middle and edges; 2) Fine-tune die gap, slightly larger in the middle and slightly smaller at edges for compensation; 3) Slightly reduce air ring airflow at edges; 4) Add restrictor bar to adjust edge flow
핵심 요약
U-shaped thickness is caused by die flow channel and swelling differences; coat-hanger die and gap fine-tuning are the key
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