Injection Molding
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Burning from mold venting in EVA '2079851475616104452
Problem Phenomenon
Insufficient venting in EVA injection mold causes air in cavity to be compressed and heated, leading to local burning
Cause Analysis
Mold vent groove area insufficient or position improper; injection speed too fast with air having no time to escape; air compressed to high temperature >200°C causing oxidative burning
Solution
1) Increase vent groove area with depth 0.02-0.03mm and width 5-10mm; 2) Set vent grooves at the last-fill area of the melt; 3) Reduce injection speed to reduce air compression; 4) Multi-stage injection with slow advancement for venting
Key Takeaway
Burning is caused by insufficient venting and high speed injection compressing air; increasing venting and reducing speed are key
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