1. Insufficient injection and pressure holding pressure of injection molding machine; 2. The back pressure is too small and the raw materials are not solid enough;

3.背壓太大,剪切、磨擦熱量增加； 4.射速太慢,未充分結晶；

3. If the back pressure is too large, the shear and friction heat will increase; 4. Too slow shooting speed and insufficient crystallization;

5.模溫太高,原料過火、分解、變質； 6.模溫太低,未充分結晶；

5. The mold temperature is too high, and the raw materials are too hot, decomposed and deteriorated; 6. Mold temperature is too low and not fully crystallized;

7.射出、保壓時間不足； 8.注塑機停機時間太長了和注塑周期太長；

7. Insufficient injection and pressure holding time; 8. The shutdown time of the injection molding machine is too long and the injection molding cycle is too long;

9.儲料時間太長； 10.二級回料在新料里添加比例太多；

9. The storage time is too long; 10. The proportion of secondary return material in new material is too large;

11.原料強度、韌性不夠，粘度不夠； 12.添加劑不合理,或添加太多；

11. Insufficient strength, toughness and viscosity of raw materials; 12. Unreasonable additives or too many additives;

13.原料未充分烘干； 14.產品內部結構有些地方太厚，有些地方太薄，不均勻,進料地方考慮不合理。

13. Raw materials are not fully dried; 14. The internal structure of the product is too thick in some places, too thin and uneven in some places, and the consideration of feeding place is unreasonable.

15.模具進料不均勻,冷料井不夠； 16.產品壁厚太薄

15. Uneven die feeding and insufficient cold well; 16. The product wall thickness is too thin

17.注塑機溫度時高時低，不穩定； 18.注塑機料管沒清理好；

17. The temperature of the injection molding machine is high and low, which is unstable; 18. The material pipe of the injection molding machine is not cleaned properly;

19.頂出不合理,塑體應力增加，產生破裂；

19. The ejection is unreasonable, and the plastic stress increases, resulting in fracture;

20.塑料件模具冷卻回路沒排好。

20. The cooling circuit of plastic mold is not arranged properly.