Plastic Material Types at Risk of Cocked or Tilted Necks
Cocked or tilted necks primarily occur in High Density Polyethylene (HDPE) and Polyethylene Terephthalate (PET) plastic during Extrusion Blow Molding (EBM), One-Step Blow Molding (ISBM), and Stretch Blow Molding (RSBM) processes.
Common Causes of a Cocked or Tilted Neck
In addition to uneven material distribution, the following can cause a cocked or tilted neck:
- Inadequate container design
- Incorrect loading of the preform into the blow mold
- Handling of the bottle before proper cooling
General Troubleshooting
Check your blow molding alignment and cooling temperatures to ensure containers are properly cooled and set before handling. Some tilted neck defects can be detected on ALPS leak testers by using non-tilting probes with harder seal durometers.