Injection Blow Molding (IBM)

  • Hybrid of intermittent injection molding + adjacent blow molding operation
  • Bottles: small personal care up to 8 oz, pharmaceutical bottles, large jars
  • Typical Resins: LDPE, HDPE, PP, PVC
  • Standard Machinery: Uniloy, Rainville, Jomar
  • Typically single layer
  • Molten plastic is injected through a manifold, into polished cavities, and onto polished cores forming preforms. The cores then index to a blowing station where the hot preforms are blown into a final geometry, all within the same machine footprint.
  • Due to the polished finish of the cavities, glass-filled grades are generally not recommended.
  • Not critical that you blow a parison while purging – these machines are easy to start back up after purging.
  • Make sure that nozzles are balanced to at least 90% for optimal processing
  • Back the injection unit away from the manifold, and follow standard injection molding purging procedures and tips.
  • Once the screw and barrel are free of contamination, move the injection unit back up to the mold and begin to extrude purging compound into and through the manifold with the injection mold open. DO NOT CLOSE THE MOLD.
  • Extrude roughly ½ barrel capacity through the manifold. Using the remaining ½ barrel capacity, run a series of high velocity short shots through the manifold to maximize pressure and cleaning.
  •  “Disco purge” – changing screw speeds, as well as stopping and starting screw rotation, allow for better screw cleaning.
  • If running PVC, it is highly important that regular purging is scheduled, to prevent the buildup of carbon in the screw and manifold.
  • Seal the injection unit with a sealing grade commercial purging compound during extended downtime events.