1. Feeder
  • Foreign matter in glass
  • Bad combustion - air/gas ratio too low
  • Oil or dirty shear blades
  • Foreign matter in the forehearth generally
  • Buildup of deposit on spout casing from the shear spray
 
1. Feeder
  • Skim the glass
  • Adjust inspirators for flameless combustion
  • Change shears
  • Check for oil-scale - carbon foreign matter, etc., in forehearth
  • Clean the underside of the spout casing and adjust shear spray

 
2. Machine Setup and Operation
  • Dirty delivery equipment
  • Insufficient cooling wind on all mold equipment
  • Excessive use of oil doper
  • Excessive swabbing
  • Plunger too hot and scaling
  • Dirty mold equipment
  • Check final blow

 
2. Machine Setup and Operation
  • Clean delivery equipment
  • Increase the cooling wind
  • Cut down on oil doper
  • Reduce amount of swabbing
  • Improve application of plunger cooling - metal spray the plunger
  • Change mold
  • Insure that there is no dirt in final blow air - fit a filter

 
3. Mold Equipment
  • Insufficient cleaning of mold equipment
  • Poor grade of plunger material

 
3. Mold Equipment
  • Clean the mold
  • Use better grade of castings

 
4. Conveyor
  • Oil blowing up through deadplate
  • Flight conveyor may have air blowing up from internal manifold

 
4. Conveyor
  • Clean the deadplate

 

Note: They may come from oil, rust, graphite, or even furnace droppings.
Check for contamination of the batch materials