Blown Film Extrusion Troubleshooting

Q1. Non-uniform Film Speed

Cause (s)

Possible Solution (s)

Unstable die head temperature

  • Check the heater function is normal
  • Check the thermocouple position is correct

Die head throughput fluctuations

  • Adjust the die gap
  • Regular cleaning of die head, screw and hilter

Non-uniform cooling air volume

  • Check air ring for dirt buildup or breakage
  • Adjust air ring position
  • Check whether air pipe is damaged

The air flow in the factory is too fast

  • Do not let outdoor air directly enter the factory

Extruder throughput instability

  • Cool down the hopper throat to avoid plastic blocking
  • Replace the strainer meshes of Filter to avoid blocking
  • Matter of the formula

Q2. Insufficient Film Strength

Cause (s)

Possible Solution (s)

Blow-up ratio

  • Use a smaller die head to increase the blow-up ratio

Improper die design or scratches

  • Clear die impurities
  • Fix scratches on the die head
  • Avoid seams by design

Material cracking

  • Change the material
  • Turn down heating temperature

Inappropriate raw material formula

  • Select raw materials with suitable Melt Index (MI)
  • Select compatible additives

Uneven gels mix

  • Use screw with a greater L/D
  • Adjust the melt temperature
  • Use multi-layer strainer meshes for filter, or reduce the die gap, to improve back pressure

Q3. Insufficient Film Openness

Cause (s)

Possible Solution (s)

Improper film roll storage

  • Avoid piling up
  • Store in a well-ventilated place

Winding tension is too high

  • Adjust the winding tension

Nip roller pressure is too high

  • Reduce nip roller pressure

Tubular film temperature is too high

  • Increase cooling air volume of air ring
  • Use cold air cooling
  • Reduce die head temperature
  • Equip take-up roller with waterway

Unsuitable material formula

  • Add anti-phase adhesive or slippery agent

Q4. Film Scratching or Wrinkling

Cause (s)

Possible Solution (s)

Tubular film asymmetry or swing

  • Adjust the air flow of air ring
  • Avoid too fast air flow inside the factory
  • Use a hash-shape frame to steady the film

Inappropriate nip roller

  • Align nip roller and keep it horizontally
  • Avoid nip roller damages

Improper collapsing frame

  • Adjust collapsing frame angle
  • Adjust collapsing frame length
  • Reduce friction to collapsing frame

Uneven winding tension

  • Adjust the winding angle

Die head scratches

  • Refinishing die scratches

Q5. Film with Fish-eye, Arrows Lines and Coking Spots

Cause (s)

Possible Solution (s)

Improper operating in material exchange

  • Avoid overheating of the gels
  • The new material should have a lower MI than the old material
  • Clean the machine before exchanging the material

Melt temperature is too high or too low

  • Adjust the melt temperature
  • Check the heater function

Raw materials contain impurities

  • Avoid dirt entering feed hopper
  • Avoid using recycled materials

Uneven gels mix

  • Increase back pressure
  • Use screw with a greater L/D
  • Avoid existence of dead corner at extruder or die head

Q6. Tubular Film Rupture

Cause (s)

Possible Solution (s)

Melt temperature is too high or too low

  • Adjust the melt temperature

Improper use of additives

  • Reduce color masterbatch
  • Reduce waste recycling rate

Insufficient melt mix

  • Add more strainer meshes of filter or reduce the die gap to increase back pressure
  • Use screw with a greater L/D

Non-smooth material feeding

  • Clean die head and screw & barrel
  • Replace the strainer meshes of filter to avoid blockage
  • Cool down the hopper
  • Remove raw materials impurities

Cooling line too low

  • Raise the cooling line

Q7. Poor Film Printability

Cause (s)

Possible Solution (s)

Inappropriate ink

  • Choose the right ink

Improper use of additives

  • Reduce the amount of additives
  • Use the appropriate surface lubricant

Insufficient corona treatment

  • Increase the treatment voltage or wattage
  • Reduce the take-up speed
  • Narrow the gap of the electrode
  • Raise the electrode treatment temperature

Air humidity too high

  • Reduce the air humidity