Injection Molding
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HDPE injection molded part warpage deformation
Problem Phenomenon
Flat HDPE products warp after demolding, the corners are not in the same plane, and the deformation continues to develop after aging.
Cause Analysis
Anisotropy of crystallization shrinkage plus uneven cooling causes different shrinkage amounts in different parts of the product; orientation stress caused by improper gate position further aggravates warpage.; during on-site troubleshooting, verify item by item according to this mechanism, and avoid blindly adjusting the machine based on experience alone
Solution
①Balance the mold cooling water circuit; ②optimize the gate position and quantity; ③extend cooling and sizing; ④adjust the holding pressure curve to reduce orientation stress.; after adjustment, take consecutive samples to verify the effect, and resume mass production only after confirming stability
Key Takeaway
HDPE warpage is jointly driven by uneven shrinkage and orientation stress; cooling balance is the preferred means, and gate optimization reduces anisotropy from the source.; after confirming effectiveness, fix the parameters and practices into the work instruction to prevent recurrence
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