Molds & Tooling
2 views
EVOH Internal Shrinkage Cavities
Problem Phenomenon
Shrinkage cavities 0.5-2mm in diameter at the center of EVOH thick-walled products
Cause Analysis
After cooling of the thick-walled area, the interior shrinks but the surface is already solidified and cannot be fed; holding time insufficient, gate freezes too early
Solution
1) Extend holding time until the gate fully freezes; 2) Increase gate size to delay freezing; 3) Product design to reduce wall thickness differences
Key Takeaway
Shrinkage cavities are caused by thick-wall shrinkage and insufficient holding; extending holding is key
Was this helpful?
0 people found this helpful
Thank you for your feedback!