the reason

1. Injection pressure or barrel temperature

2. Too much feed

3. The advancing time of the pump is too long

4. Write more and feel the unbalanced feed inlet,

5. There are recesses in the mold

6. Deep tube part demoulding vacuum problem

7. Change of mold opening time

8. Improper finishing of the mold surface

9. Die center misalignment

Corresponding measures

1) Reduce the injection pressure or the barrel temperature is too high

2) Reduce feedstock 　

3) Reduce the advancing time of the pump

4) Limit the plastic flow, as close as possible to the main channel or the unbalanced feed ports of the single mold

5) Eliminate dents, polish or increase demoulding angle

6) Provide sufficient escape airway

7) Maintain a fixed mold opening time, if necessary, use a timer

8) Polishing mold surface

9) Adjust the die core and lock it with the withdrawal angle