Plastic Injection Troubleshooting

Below is a list of plastic injection defects. This troubleshooting guide offers some potential ways to correct the defect listed. Adjustments might require that one, several or all of the changes listed. Adjustments should always be made with an understanding of why the change is being made, and that other defects might occur. If in doubt, ask a process engineer or technical support employee for best practice. This is a primary list, and does not offer all solutions for defect correction.


  • Examine mold for parting line damage
  • Clean mold and vents
  • Verify that process has been decoupled
  • Lower hold pressure
  • Raise Cut-off
  • Slow injection speed in area of fill
  • Lower melt temperature (Refer to MSDS for melt range prior to change
  • Increase tonnage
  • Lower mold temperature
  • Use bluing agent to verify parting line seal off


  • Check material moisture content
  • Verify melt Temperature is within melt temperature window, as established by MSDS supplied by material manufacturer
  • Check mold for water/ oil leak
  • Slow down injection speed overall, or in area of fill
  • Inspect nozzle tip for damage
  • Lower heat profile
  • Reduce back pressure
  • Check material for over drying
  • Inspect nozzle tip for proper size
  • Check for consistent cushion (cracked/ damaged check ring)
  • Check mold for signs of damage/ burring

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