Molds & Tooling
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COC Demolding Damage
Problem Phenomenon
COC products crack, whiten or surface scratched during ejection, deep-cavity transparent parts have obvious ejection marks, automated demolding interruption rate high.
Cause Analysis
COC is rigid and brittle, ejection stress concentration easily cracks; insufficient draft angle and undercut structure make demolding resistance too large; small ejector pin area concentrates pressure and damages the surface.
Solution
①Adopt as large draft angle as possible (refer to polystyrene standard); ②minimize undercuts; ③configure sufficient number of large-area ejector pins or stripper plate demolding; ④optimize ejection speed curve for slow start.
Key Takeaway
COC demolding design standard aligns with PS; large draft angle and large-area ejection are the two iron rules; ejection damage prevention of brittle materials beats all post-remediation.; after confirming effectiveness, fix the parameters and practices into the work instruction to prevent recurrence
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