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