Molding Process
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Structural Factors of PC Stress Cracking
Problem Phenomenon
The products crack concentratedly at sharp corners, notches or wall thickness transitions, with cracks initiating from stress concentration points
Cause Analysis
Sharp corners, right angles and wall thickness transitions cause stress concentration, amplifying the local stress several times; PC has strong notch sensitivity, and stress concentration areas crack first under the action of solvents or loads
Solution
①Round all internal corners with R≥0.5mm and eliminate V-shaped grooves; ②control the wall thickness difference within 20% and the transition slope ≤1:3; ③rib thickness not exceeding 60% of the main wall thickness
Key Takeaway
Structural design determines the upper limit of the stress distribution of PC parts; fillets, uniform wall thickness and gentle transitions are the three anti-crack design principles, which must be implemented before mold making; after confirming effectiveness, solidify the parameters and practices into the work instruction to prevent recurrence
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