Injection Molding
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Sink Marks in CMC '2079851475616104452
Problem Phenomenon
Surface depression of 0.2-0.5mm in thick-walled areas of CMC injection molded products (sink marks)
Cause Analysis
Holding pressure is insufficient or holding time is short; gate freezes prematurely and holding pressure cannot be transmitted; wall thickness difference is large, and after the thin wall freezes, the thick wall cannot be fed
Solution
1)Increase holding pressure 70-90MPa; 2)Extend holding to gate freezing +2s; 3)Product design reduces wall thickness differences with gradual transitions; 4)Add supplementary gates in thick-walled areas
Key Takeaway
Sink marks are caused by insufficient holding and wall thickness differences; high-pressure holding and multiple gates are core countermeasures
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