Molds & Tooling
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POM product brittle cracking and insufficient toughness
Problem Phenomenon
Products crack brittlely when dropped or assembled, with flat fracture surfaces, while hand-made test bars of the same material have normal toughness.
Cause Analysis
Too high processing temperature or too long residence degrades and lowers the molecular weight; too low mold temperature with large internal stress and weld lines designed in stressed areas also induce brittle cracking.; during on-site troubleshooting, verify item by item according to this mechanism, and avoid blindly adjusting the machine based only on experience
Solution
①Control melt temperature and residence time; ②increase mold temperature to reduce internal stress; ③optimize the gate to avoid weld lines in stressed areas; ④test the degree of degradation.; after adjustment, continuously sample to verify the effect, and resume mass production only after confirming stability
Key Takeaway
Brittle cracking requires distinguishing between two types of causes: material degradation and structural stress; check temperature history for degradation, and check mold temperature and gate for stress, treating each accordingly.; after confirming effectiveness, fix the parameters and practices into the work instruction to prevent recurrence
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