Molding Process
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PMMA Sink Marks
Problem Phenomenon
Depressions on the back of thick walls and ribs, appearing as optical distortion in transparent parts.
Cause Analysis
Uneven wall thickness + insufficient feeding; hard pressure feeding in turn increases internal stress and induces delayed cracking.
Solution
①Uniform wall thickness (0.635~3.81mm); ②Rib thickness ≤50%~60%; ③Moderate holding pressure; ④Reduce material in thick walls.
Key Takeaway
PMMA sink marks rely on structure, hard pressure trades for delayed cracking.
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