July 29, 2014

Ejector mark defect on plastic products

1.    Definition.
Ejector mark is a concave or a convex on the surface of plastics product. It causes rapid variation in thickness which leads to gloss differences and concaves.

ejector mark

ejector mark

2.    Cause of ejector marks.
+ Injection molding process-related cause (ex: early opening mold or high release force due to incorrect machine setting.)
+ Shape-related cause (ex: Defective assembly and inaccurate length of ejector)
+ Machine and strength-related cause (ex: Defective measuring & design of mold, product or ejector system)
+ Thermal cause (ex: Huge temperature difference between ejector and mold or inside of a mold)

Ejector pin & ejector pin mark

Ejector pin & ejector pin mark

3.    Improve ejector mark.
+ Mold lapping.
+ Increase wall thickness.
+ Make draft angle for ribs, boss,… of  plastic product.
+ Re-setting ejector system.
+ Increase cooling time,..

improve ejector mark

improve ejector mark

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