Ejector marks / whitening
Marks, whitening or punch-through where the ejector pins are located.
Symptoms
- Round glossy/dull mark in the pin area
- White stress mark
- Punch-through or crack in the part
Tip: If the part sticks to the mold while cooling, add an ejection delay.
Order of solutions
- Increase the cooling time
- Reduce the holding pressure
- Reduce the ejection speed and force, use stepped ejection
- Review the draft angle and the surface polish in the mold
- Increase the number or diameter of the ejector pins; add air ejection
Likely causes
Process setting
- Cooling short, part is ejected while soft
- Excessive holding (the part sticks to the mold)
- Ejection speed/force too high
Mold
- Draft insufficient or surface rough
- Too few ejector pins or diameter too small
- Vacuum forms
Part design
- Little draft
- Deep and narrow ribs
Was this information helpful? If you notice anything missing or wrong, please .
Other defects
Short shot (incomplete fill)
The cavity does not fill completely; the farthest or thinnest area of the part stays incomplete.
Flash
Plastic escapes through the parting line or around the ejector pins.
Sink mark
A dent on the surface opposite a thick section; the surface is drawn inwards.
Void (internal vacuum void)
Internal cavity in a thick section of the part; the outer surface may look perfect.