Molding Process
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POM weld line weak strength
Problem Phenomenon
Fracture at the weld line.
Cause Analysis
POM crystallizes extremely fast, the melt fronts freeze quickly where they meet, and the molecular entanglement window is extremely short; cold fronts inevitably produce weak weld lines.
Solution
①Increase melt temperature (still must be <230℃) or mold temperature; ②increase injection speed; ③adjust the gate so the weld line avoids the stressed area; ④vent at the meeting point.
Key Takeaway
POM weld lines = racing against crystallization speed.
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