Injection Molding
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EVOH injection molded product ejector whitening
Problem Phenomenon
White marks (ejector whitening) appear at ejector pin positions on EVOH injection molded products, affecting appearance
Cause Analysis
Ejector pin force too large causing local compression deformation whitening; insufficient cooling time with the product ejected before full solidification; ejector pin area too small with stress concentration
Solution
1) Extend cooling time so the product is ejected after full solidification; 2) Increase ejector pin area using ejector plate instead of small ejector pins; 3) Reduce ejection speed to reduce impact; 4) Increase draft angle to reduce ejection force
Key Takeaway
Ejector whitening is caused by excessive ejection force and insufficient cooling; increasing ejector pin area and extending cooling time are key
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