Molding Process
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PC metal insert preheating
Problem Phenomenon
PC parts with metal inserts crack around the inserts, especially severe after thermal cycling
Cause Analysis
Metal and PC have large differences in thermal expansion coefficient; during cooling, the PC around the insert is under tensile stress; cold inserts also cause the contact surface melt to cool rapidly forming weak interfaces and stress concentration
Solution
①Inserts preheated to above 100-120℃ before molding; ②Wall thickness around inserts thickened with rounded transitions; ③Minimize the number of inserts, switch to post-assembly structure
Key Takeaway
The expansion mismatch between inserts and PC is a structural contradiction; preheating, thickening, and reducing inserts are used together, and design changes to bypass inserts when necessary；After confirming effectiveness, solidify the parameters and practices into the work instruction to prevent recurrence
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