Molds & Tooling
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PVC Burnt: Check Temperature First
Problem Phenomenon
Burnt black specks appeared on products; the operator adjusted the mold and speed first, and the problem recurred
Cause Analysis
PVC defect statistics show temperature-related defects account for 55-60%; the first check item for burnt black specks is always temperature and residence time, not mold or speed; during on-site troubleshooting, verify item by item according to this mechanism to avoid blindly adjusting the machine based only on experience
Solution
①For burnt, first check melt temperature and residence time; ②second check shear factors—screw speed and gate; ③finally check venting and mold; after adjustment, continuously sample to verify the effect, and resume mass production after confirming stability
Key Takeaway
PVC troubleshooting has a clear priority; temperature first, shear second, venting third—checking in order is most efficient; after confirming effectiveness, fix the parameters and practices into the work instruction to prevent recurrence
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