Injection Molding
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EVOH Surface Tiger Stripes
Problem Phenomenon
EVOH injection molded product surfaces show tiger stripes, alternating light-dark bands 2-5mm wide
Cause Analysis
Injection speed unstable, melt front fluctuating fast and slow; mold temperature too low <30°C, front rapidly cooling
Solution
1) Multi-stage injection slow-fast-slow to stabilize the front; 2) Increase mold temperature to 40-50°C; 3) Increase injection pressure for stable advancement
Key Takeaway
Tiger stripes are caused by unstable injection front; multi-stage injection and high mold temperature are key
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