Molds & Tooling
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Internal stress warpage from too low PP mold temperature
Problem Phenomenon
The warpage defect rate of products produced at a mold temperature below 40℃ increases significantly, and the deformation continues to develop after aging.
Cause Analysis
Low mold temperature makes the crystallization rates inside and outside the product inconsistent, and internal stress increases severalfold; uneven crystallization also causes shrinkage differences, and the dual action triggers warpage.; during on-site investigation, verify item by item according to this mechanism to avoid blindly adjusting the machine based only on experience
Solution
①Increase the mold temperature above 40℃ and keep it stable; ②balance the temperature difference between cavity and core; ③judge dimensions after aging the product for 24 hours; ④control the mold temperature within ±2℃ for precision parts.
Key Takeaway
Mold temperature is the master switch of PP crystallization and stress; the cold-mold process below 40℃ seems to have a fast cycle, but actually comes at the cost of warpage risk.; after confirming effectiveness, solidify the parameters and practices into the work instruction to prevent recurrence
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