Molds & Tooling
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GPPS Product Brittle Cracking
Problembeschreibung
Transparent PS products crack upon demolding or slight force, and cracks mostly start at corners, rib positions or weld lines.
Ursachenanalyse
Material overheating or over-shearing reduces molecular weight and makes it brittle; improper molding conditions produce high internal stress, and one-sided rapid cooling causes stress differences, all of which make GPPS brittle and crack.
Lösung
①Check barrel temperature to prevent overheating degradation; ②optimize molding conditions to reduce internal stress; ③balance cooling to avoid one-sided rapid cooling; ④when cracking occurs at weld lines, move the gate to change the filling pattern.
Wichtigste Erkenntnis
GPPS brittle cracking should be investigated along two lines: material degradation and internal stress; transparent parts can use polarizers to observe stress distribution to assist positioning.; after confirming effectiveness, fix the parameters and practices into the work instruction to prevent recurrence
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