Injection Molding
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ABS holding pressure ratio to prevent sink marks
Problem Phenomenon
[Problem phenomenon] Improper ABS holding pressure, thick-wall sink marks and over-holding stress coexist
Cause Analysis
Holding pressure is 50-70% of injection pressure to compensate 0.4-0.7% shrinkage; insufficient holding pressure causes sink marks and voids, too high causes internal stress and demolding difficulty; during on-site troubleshooting, verify item by item according to this mechanism, avoiding blind machine adjustment based solely on experience
Solution
Holding pressure set at 50-70%; extend time at thick-wall rib positions; gate freezing determines the holding pressure end point; after adjustment, continuously sample to verify the effect, and resume mass production only after confirming stability
Key Takeaway
ABS holding pressure 50-70% compensates shrinkage, thick-wall time extension is the key; after confirming effectiveness, fix 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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