Injection Molding
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Crystalline White Spots Near the Gate of PBT Injection-Molded Parts
Problem Phenomenon
White opaque areas appear near the gate of PBT products, with an obvious color difference from the main body.
Cause Analysis
Shear-induced crystallization at the gate forms spherulites; rapid cooling causes incomplete crystal growth, resulting in whitening; the gate size is too small and the shear is large.
Solution
Increase the gate size to reduce shear; increase the mold temperature in this area; reduce the injection speed.
Key Takeaway
PBT gate white spots are the result of shear-induced crystallization.
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