Injection Molding
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POM Pits and Pockmarks
Problem Phenomenon
Pits and pockmarks appear on the part surface, different in form from sink marks, with irregular distribution
Cause Analysis
Pockmarks originate from insufficient feeding or poor venting: feeding fluctuation, low injection pressure, low mold temperature, and too small cushion all cause poor cavity replication; at poorly vented spots, compressed gas forms pits
Solution
①Increase feeding and injection pressure; ②raise mold temperature and injection speed; ③add venting and enlarge gates and runners; after adjustment, take continuous samples to verify the effect, and resume mass production only after confirming stability
Key Takeaway
Troubleshoot POM pockmarks along the three lines of feeding, mold temperature, and venting; the difference from sink marks lies in distribution pattern and causal path; after confirming effectiveness, solidify the parameters and practices into the work instruction to prevent recurrence
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