Processing Machinery
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POM Sink Mark Control
Problem Phenomenon
Sink marks behind ribs of POM parts are obvious
Cause Analysis
Insufficient feeding for thermal junction shrinkage at ribs; POM's large crystallization shrinkage makes sink marks more obvious; during on-site troubleshooting, verify item by item according to this mechanism, and avoid blindly adjusting the machine based only on experience
Solution
Control rib thickness to 50% of the main wall; increase holding pressure and time; aim the gate position at the thick wall; after adjustment, take continuous samples to verify the effect, and resume mass production only after confirming stability
Key Takeaway
POM sink marks require dual control of design ratio and holding pressure; after confirming effectiveness, solidify the parameters and practices into the work instruction to prevent recurrence; include this case in the defect archive as a troubleshooting reference for subsequent similar problems
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