1. Feeder
  • Gob temperature is too low
  • Incorrect gob shape
1. Feeder
  • Increase gob temperature
  • Improve shape of gob

 
2. Machine Setup and Operation
  • Excessive counterblow time or excessive blank contact time-parison too hard
  • Insufficient reheat time on mold side prior to final blow
  • Insufficient pressure, or application of final blow too soon
  • Dirty shoulder vents
  • Incorrect cooling wind application-blanks or blow molds too cold
  • Dirty mold
  • Blow head not seated correctly on mold

 
2. Machine Setup and Operation
  • Shorten counterblow time and blank contact time
  • Allow more reheat time before final blow
  • Increase the final blow pressure and delay start of final blow
  • Change mold
  • Reduce cooling wind application
  • Change the blow molds
  • Adjust blow head on mold

 
3. Mold Equipment
  • Mold not properly vented
  • Tap of mold damaged so that final blow enters the mold
  • Blow head too deep
  • Unsuitable blow head seat venting

 
3. Mold Equipment
  • Vent mold correctly
  • Change mold and have old mold repaired
  • Change blow head and have old blow head cleaned
  • Ensure venting of blow heat seat is correct

 

Note: Gives a bad appearance to the container and may cause problems on the filling line. It can also cause under-capacity