Injection Molding
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EVOH '2079851475616104452 Flow Marks
Problem Phenomenon
EVOH injection molded product surfaces show radial flow marks centered on the gate
Cause Analysis
Injection speed too fast causing unstable melt front; mold temperature too low <30°C, the front cools rapidly forming marks
Solution
1) Use multi-stage injection speed slow-fast-slow to control front stability; 2) Increase mold temperature to 40-50°C to delay front cooling; 3) Stabilize injection pressure to avoid fluctuations; 4) Increase gate area to reduce sudden pressure changes at the gate
Key Takeaway
Flow marks are caused by unstable injection front and rapid cooling; multi-stage injection and high mold temperature are key
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