Injection Molding
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Ejector whitening on EVA injection molded products
Problem Phenomenon
White marks (ejector whitening) appear at ejector pin positions on EVA injection molded products, affecting appearance
Cause Analysis
Ejector pin force too large causing local compression deformation and whitening; insufficient cooling time with product ejected before full solidification; ejector pin area too small with stress concentration
Solution
1) Extend cooling time to eject after full solidification; 2) Increase ejector pin area using ejector plate instead of small pins; 3) Reduce ejection speed to reduce impact force; 4) Increase demolding draft 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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