Injection Molding
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PP '2079851475616104452 Warpage Deformation
Problem Phenomenon
After ejection, PP parts twist and bow, flat parts warp at edges, making assembly difficult.
Cause Analysis
PP is a semi-crystalline material with shrinkage as high as 1.5%~2.5% and strong directionality; differential shrinkage caused by uneven cooling, wall thickness differences, and molecular orientation all cause warpage.
Solution
①Separate circuit temperature control for core/cavity with temperature difference <5℃; ②appropriately raise mold temperature (e.g., 40℃→55℃) for more uniform and sufficient cooling; ③reduce holding pressure by 15%~25% to reduce frozen stress; ④extend cooling time by 20%~30%; ⑤optimize wall thickness uniformity.
Key Takeaway
PP warpage takes 'uniform cooling + sufficient crystallization' as the main direction of attack.
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