Injection Molding
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Ejector whitening in demolding of PET injection molded parts
Problem Phenomenon
White spots or cracks appear at ejection positions of PET products, especially obvious in transparent products.
Cause Analysis
Ejection force is too large or the ejector pin area is too small, causing excessive local stress; draft angle is insufficient; mold temperature is on the high side and rigidity is insufficient.
Solution
Increase ejector pin area or number to disperse ejection force; increase draft angle to ≥2°; extend cooling time.
Key Takeaway
PET ejector whitening is the result of local stress exceeding material strength.
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