Extrusion Shuttle Blow Molding (EBM)

  • Continuous extrusion process – the molds shuttle back and forth to grab the parison, then away from the head to blow the parison.
  • Bottles: personal care up to 20 oz, pharmaceutical, large jars
  • Typical Resins: LDPE, HDPE, PP, PVC, extrudable PET(ePET), “soft touch” resins.
  • Standard Machinery: Bekum, Techne, Kautex, R&B Plastics, Magic
  • Often multiple extruders for multiple bottle layers
  • Typical layers would be virgin, re-grind, adhesive, barrier, virgin + color, etc.
  • Dies are not polished – glass filled grades are generally safe to use
  • Not critical that you hold a parison while purging – these machines are relatively easy to start back up after purging, and gravity will control the purge after exiting the head tooling.
  • All extruders do not need to be purged the same – perhaps the Ethylene vinyl alcohol (EVOH) and virgin layers are contaminant free, for example. Purge only the extruders that need it.
  • Run the die as close to closed as safely possible to increase melt pressure and shear – keep an eye on extruder amps to make sure that you are not overworking the motor.
  • “Disco purge” – changing screw speeds, as well as stopping and starting screw rotation, allow for better screw cleaning.
  • Efficient EBM department operations are all about scheduling colors in order from light to dark as much as possible, and using a purging compound when moving back from dark to light.
  • Seal the extruder and head with a sealing grade commercial purging compound during extended downtime events.