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Troubleshooting Injection Moulding

Defect

Causes
Flash
  • Injection pressure too high
  • Clamp force too low
Warping
  • Non-uniform cooling rate
Bubbles
  • Injection temperature too high
  • Too much moisture in material
  • Non-uniform cooling rate
Unfilled sections
  • Insufficient shot volume
  • Flow rate of material too low
Sink marks
  • Injection pressure too low
  • Non-uniform cooling rate
Ejector marks
  • Cooling time too short
  • Ejection force too high

 

Many of the above defects are caused by a non-uniform cooling rate. A variation in the cooling rate can be caused by non-uniform wall thickness or non-uniform mold temperature.   For more troubleshooting guidance, you may download our Injection Moulding Troubleshooting Guide.