Holes in plastic containers can occur at any step of the blow molding process for a variety of reasons.
Plastic Material Types at Risk of Holes
Holes are primarily found in Polyethylene Terephthalate (PET) plastic during the Extrusion Blow Molding Process (EBM), although they can occur in all plastic materials (HDPE, PP, PVC, etc.) and all processes (IBM, RSBM, or ISBM).
Common Causes of Holes
The most common causes of holes in plastic containers include:
Contamination particles within the resin. The contaminated area does not stretch like plastic, so the surrounding areas are left thin and susceptible to holes.
Improper material distribution can cause an uneven container surface with thicker and thinner areas. When the thinner areas are stretched, a hole can occur.
Improper mold setup or wear, including:
Low blow pressure or blow rate
Plugged or inadequate vents
Air leak around the blow pin
Mold does not close properly
Mold doesn’t pinch the parison properly to seal the top or bottom, an EBM problem
General Troubleshooting
Checking for contamination in the resin, ensuring proper mold alignment, and confirming proper melt temperature and blow air pressure are great places to start.
ALPS Inspection is proud to be a market leader in manufacturing in-line leak inspection equipment for empty plastic containers of all sizes, shapes, and materials. Our team of experts provides thorough defect analysis and feasibility testing services, giving you the valuable insight needed to improve defect detection and ensure optimal leak detector performance.
Have a plastic container defect sample? Request a defect analysis with our feasibility testing team today!
