1. Plastic injection molding machine and pressure maintenance pressure;

2. Back pressure is too small, raw material is not solid enough;

3. The back pressure is too large, the shearing and friction heat increase;

4. The firing speed is too slow and not fully crystallized;

5. The plastic injection mold temperature is too high, the raw material is over fire, decomposed and deteriorating;

6. The plastic injection mold temperature is too low and not fully crystallized;

7. Insufficient injection and holding time;

8. Plastic injection molding machine downtime is too long and the injection cycle is too long;

9. The storage time is too long;

10. The secondary return material is too much added in the new material;

11. Material strength, toughness is not enough, viscosity is not enough;

12. Additives are not reasonable, or add too much;

13. The raw materials are not fully dried;

14. The internal structure of the product is too thick in some places, some places are too thin and uneven, and the feeding place is considered unreasonable.

15. Mold feeding is not uniform, cold material well is not enough;

16. Product wall thickness is too thin;

17. The temperature of the plastic injection molding machine is high, low, and unstable;

18. The plastic injection molding machine material tube is not cleaned;

19. The ejection is irrational, the stress of the plastic body increases, and a crack occurs;

20. The plastic mold cooling circuit is not lined up