Common injection molding defects of polypropylene




Fault analysis and Troubleshooting:

(1) Gate and runner dimensions are too small. It should be increased appropriately.

(2) The injection pressure is too low. It should be improved appropriately.

(3) The moisture content in the raw material is too high. The raw materials should be pre dried.

(4) The wall thickness of plastic parts changes too much. The shape and structure of plastic parts should be designed reasonably to avoid the sharp change of wall thickness.


craze crack

Fault analysis and Troubleshooting:

(1) The temperature of melt and mould is too low. The temperature of barrel and die should be increased.

(2) The structure design of gating system is unreasonable. The structure of runner and gate should be improved to avoid turbulence during mold filling.

(3) The cooling time is too short. The cooling time should be extended appropriately.

(4) The design of ejection device is unreasonable. It is better to use pneumatic demoulding device.

(5) Injection speed and pressure are too high. It should be reduced appropriately.


Bending deformation

Fault analysis and Troubleshooting:

(1) Mold temperature too high or insufficient cooling. The mold temperature should be reduced or the cooling time should be extended. For the slender plastic parts, the cooling method can be adopted after the mold is fixed.

(2) Uneven cooling. The cooling system of mould should be improved to ensure uniform cooling of plastic parts.


(3) The gate selection is unreasonable. The reasonable gate form should be selected according to the specific situation. In general, multipoint gate can be used.

(4) The mold is eccentric. It should be checked and corrected.