Problem Possible causes Possible solution
  Blocking Insufficient bubble cooling Optimise cooling air
 Reduce output rate
 Winding tension too high Reduce winding tension
 Nip roller pressure too high Reduce nip roller pressure
 Rolls exposed to excessive heat during storage or transport Minimise heat exposure
 Antiblock level or type is not adequate Increase level of antiblock
 Consider a different type of antiblock
 Formulation susceptible to blocking Consider metallocene resins or higher density resins
  Die lines or Die lip buildup Melt temperature too high Reduce extruder temperatures
 Die temperatures too high Reduce die temperatures
 Insufficient process aid Add process aid masterbatch
 Antiblock Reduce level if possible. Check type of antiblock.
 Die lips scratched or dented Repair or replace lip set
 Die lips misaligned Ensure die lips are aligned and level
  Gels or dark specks Oxidation of resin during shutdown or startup Cool extruder rapidly when shutting down (set temperatures to 100°C)
 Avoid long periods of heating while extruder idle
 Leave extruder full when shutting down
 Add antioxidant masterbatch when shutting down
 Extrusion temperatures not optimised Optimise extrusion temperatures
 Extruder speed too slow or too fast for optimum extrusion Alter formulation or equipment to achieve suitable extruder speeds
 Purging inadequate when changing formulations Consider use of a purging compound
 Faulty thermocouple, or other fault in heating or cooling systems Check heater controls, thermocouples, and cooling system
 Screenpack broken Replace screenpack
 Screens too coarse Use finer screen(s)
 Contamination Eliminate sources of external contamination
 Moisture Ensure resins are dry
 Buildup of oxidised material in equipment Clean extruder screw and barrel. Clean die.
  Incorrect COF / slip Incorrect level of slip additive Check dosing
 Consider type of slip additive
 Slip additive has not migrated to surface Allow adequate time for additive to migrate
 Reduce winding tension
 Slip levels in each layer not optimised Alter slip levels in each layer
 Slip additive absorbed by another layer Consider non-migratory slip additive
  Low output Unstable bubble Refer to "Unstable bubble" section
 Extruder motor load too high Increase extrusion temperatures
 Consider higher melt index resin(s)
 Regear extruder motor
 Head pressure too high Change screenpack
 Increase extrusion temperatures
 Consider higher melt index resin(s)
 Increase die size or die gap
  Melt fracture Melt temperature too low Increase extruder and/or die temperatures
 Die gap too narrow Change die insert to a larger gap
 Insufficient process aid Add or increase process aid masterbatch
 Formulation not optimum Add or increase level of LDPE
 Consider a different grade of LLDPE
 Output rate too high Reduce output rate
  Poor optical properties Melt temperature too low Increase extruder and/or die temperatures
 Frost line too high Reduce frost line height
 Output rate not optimum Increase or reduce output rate
 Melt fracture Refer to "Melt fracture" section
 Die gap too wide Change die insert to a narrower gap
 Excessive level of antiblock or other additives Optimise additive levels
 Formulation not optimum Consider lower density resins
 Consider higher melt index resins
 Add or increase level of LDPE
  Poor shrink properties Incorrect blow up ratio Adjust die size or film width
 Incorrect resin or formulation for application Adjust level of LLDPE / HDPE or alter grade of LDPE
 Poor gauge control Minimise variation by centering die and optimising chilled air flow
 Frostline height not correct Adjust chilled air flow or output rate
 Bubble shape not correct Adjust chilled air flow or output rate
 Die lip gap not optimum Replace die lip set
  Poor sealing Faulty sealing equipment Ensure sealing equipment is well maintained
 Sealing temperature or dwell time too low Increase sealing temperature or dwell time
 Sealing temperature too high Reduce sealing temperature
 Sealing pressure too low or too high Adjust sealing pressure
 Consider different type of sealing jaw or wire
 Gauge incorrect Ensure target gauge is achieved
 Gauge variation Minimise variation by adjusting die gaps and optimising chilled air flow
 Incorrect formulation Ensure no errors occur in feeding or blending resins
 Excessive corona treatment Reduce corona treatment level
 Formulation not optimum for conditions Adjust formulation (will depend on failure type)
  Surging extruder Feedthroat cooling not working Check cooling water flow
 Bridging or blockage in feed throat Check feedthroat
 Temperature profile not optimised Optimise extruder temperatures
 Inconsistent resin blend Ensure blenders are operating correctly
  Unstable bubble Cooling air flowrate not optimised Adjust cooling air
 Ensure air ring type is suitable for formulation
 Melt strength too low Reduce melt temperature
 Use material with lower MI
 Add or increase level of LDPE
 Surging extruder Refer to "Surging extruder" section
 High blow up ratio Increase die size
 Output rate too high Reduce output rate

The information contained in these guidelines is provided in good faith and may assist with problem solving and troubleshooting.

The information is offered solely for your information and is not all-inclusive – other variables or constraints may impact the ability of the user to apply them. The user should conduct its own investigations and satisfy itself as to whether the information is relevant to the user’s requirements. The user should not rely upon the information in any way. The information shall not be construed as representations of any outcome for which Qenos assumes any legal liability. Qenos expressly disclaims liability for any loss, damage, or injury directly or indirectly suffered or incurred as a result of or related to anyone using or relying on any of the information. There is no endorsement of any product or process, and Qenos expressly disclaim any contrary implication.