Problem:
Sink marks occur on the "A" surface of the molding.

Solution:

1. Check if melt cushion is less than 5 mm - increase.
2. Check function of the non return valve .
3. Experiment with increasing hold pressure time.
4. Increase the hold pressure.
5. Reduce the temperature of the mould.
6. Reduce the melt temperature.
7. Reduce the injection speed.
8. Extend the cooling time.
9. Increase the gate size.
10. Check wall thickness in the gate area.
11. Make the ribs thinner.

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