Molding Process
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PA6 Thick-Wall Sink Marks and Burnt
Problem Phenomenon
Sink marks and vacuum voids appear in products with wall thickness above 6mm, and there are even burnt marks in the thick-wall center
Cause Analysis
PA6 crystallization and solidification cause large volume shrinkage, and insufficient feeding compensation in the thick-wall zone forms sink marks and vacuum voids; heat dissipation inside the thick wall is slow, and accumulated shear heat may also cause local overheating and burnt
Solution
①Increase holding pressure and time to compensate for volume shrinkage; ②Strengthen cooling in the thick-wall zone and optimize the gate holding channel; ③Control melt temperature to prevent shear heat accumulation; after adjustment, continuously sample to verify the effect, and resume mass production only after confirming stability
Key Takeaway
Thick-wall PA6 parts need prevention of both sink marks and overheating; holding compensation and cooling enhancement work in both directions, and the gate channel is the throat of feeding compensation; after confirming effectiveness, solidify the parameters and practices into the work instruction to prevent recurrence
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