Extrusion & Post
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PC annealing treatment specification
Problem Phenomenon
Product internal stress exceeds standard, transparent parts have optical distortion, and crack immediately after solvent wiping
Cause Analysis
Orientation stress frozen during molding is not released, and the product is in a metastable state; when encountering solvent, load, or temperature difference, stress release manifests as cracking; annealing can relax molecular chains back to stability
Solution
①Hot air circulation oven annealing at 110-130℃ for 2-4 hours, add 0.5 hour for every 1mm increase in thickness; ②Slow cooling after annealing ≤20℃/h; ③Annealing temperature takes 10-20℃ below the heat deflection temperature
Key Takeaway
Annealing is the standard post-treatment for PC to eliminate internal stress; temperature, time, and slow cooling three parameters are executed per specification, never fast-cool and waste previous efforts；After confirming effectiveness, solidify the parameters and practices into the work instruction to prevent recurrence
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