Molds & Tooling
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Product continuous post-shrinkage after placement
Problem Phenomenon
The product dimensions continuously and slowly change after demolding, still unstable after 24h
Cause Analysis
The molecular chains in the amorphous regions of the PP matrix continue to relax and rearrange at room temperature; the post-crystallization process of PP continues to room temperature; slow release of molding residual stress
Solution
Extend cooling time in the mold by more than 30%; anneal the product immediately after demolding (120°C/2h); reduce injection and holding pressure to reduce molecular orientation
Key Takeaway
The impact of post-shrinkage on precision assembly parts cannot be ignored
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