20.6.10 Pitted Parts
The nished product contains unmelted particles or small holes on the
surface.
Probable Cause:
1. Molding Machine
• Improper or worn out feed screw
• Low melt temperature
• Low injection speed
2. Mold
• Gating shear
• Sharp corners
3. Material
• Resin used is not homogeneous
• External contamination
Solution (in sequence):
1. Reduce shear
2. Reduce back pressure
3. Reduce injection speed
4. Modify temperature
5. Modify regrind ratio
6. Modify shot size
7. Inspect Hot Runner and nozzles
20-14
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