Injection Molding
3 views
Burnt Marks from Insufficient Mold Venting in PU '2079851475616104452
Problem Phenomenon
PU injection mold venting insufficient, air in the cavity compressed and heated causing local burning
Cause Analysis
Mold vent groove area insufficient or position improper; injection speed too fast, air has no time to escape; air compressed to high temperature >200°C causing oxidative burning
Solution
1) Increase vent groove area, depth 0.02-0.03mm, width 5-10mm; 2) Set vent grooves at the last-fill areas of the melt; 3) Reduce injection speed to decrease 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
Was this helpful?
0 people found this helpful
Thank you for your feedback!