Stretch Blow Molding (SBM)

  • Hybrid of intermittent injection molding + adjacent blow molding operation
  • Bottles: small clear or highly transluscent personal care up to 8 oz, pharmaceutical bottles
  • Typical Resins: PET, some oriented polypropylene (oPP)
  • Standard Machinery: Aoki, Nissei
  • Typically single layer
  • Molten plastic is injected through a manifold, into cavities, and onto injection cores. The preforms then index to a blowing station, where they are blown into a final geometry, all within the same machine footprint.  Note: preforms may pass through a conditioning station between injection and blow, depending on machine platform.
  • Do not attempt to mold or blow parisons
  • Focus on cleaning the injection unit first, by backing it away from the manifold and following standard injection molding purging procedures
  • To minimize carbon contamination, keep nozzle drool to a minimum, and clean nozzle drool regularly to keep it from entering the manifold.
  • Use a regular purging schedule to keep preforms free of contamination
  • Weigh and record nozzle drool to make sure that you are always trying to improve your process.
  • When using a purging compound, it is generally best if they are added directly to the feedthroat, as opposed to being dried with the resin. The drying process could actually activate some foaming agents in chemical purges.
  • Seal the injection unit with a sealing grade commercial purging compound during extended downtime events.