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Top PET Blow Molding Problems and How to Solve Them (Part 2)
Producing premium-quality Pet Bottles requires more than just top-grade raw materials—it hinges on precision control of the blow molding process.
Even with advanced machinery in place, manufacturers often face recurring problems that compromise clarity, durability, and uniformity. This guide outlines typical issues encountered during PET bottle production and provides practical, easily applicable solutions to enhance output quality and minimize production losses.
- Wrinkles or Excess Material at the Bottom/Neck
Root Causes:
Blowing cycle too long
Uneven air distribution
Insufficient heat in affected zones
Inconsistent air pressure impacting Stretch Rod movement
Recommended Fixes:
Shorten blowing duration or decrease stretch rod speed
Balance air delivery across both sides of the mold
Increase heating in the wrinkled or thickened areas
Install an air reservoir or reduce the air line length to stabilize pressure
- Base Piercing During Stretching
Root Causes:
Preform is underheated
Excessive stretching force or time
Weak preform base or pointed stretch rod tip
Recommended Fixes:
Raise the preform temperature
Lower the stretch ratio or shorten stretch time
Reinforce base design of the preform
Round off the stretch rod tip to reduce piercing risk
- Bottle Blowouts
Root Causes:
Insufficient preform heating
Stretch rod fails to reach the mold bottom
Slow rod descent
Overly broad protection temperature settings
Recommended Fixes:
Boost heating power or reduce preform feeding speed for more consistent heating
Verify and adjust stretch rod position to ensure full stroke
Open the throttle valve to increase descent speed
- Bottom Misalignment
Root Causes:
Stretch rod descends too slowly
Blowing time is too short
Significant preform eccentricity
Recommended Fixes:
Maximize throttle valve opening for faster rod descent
Extend blowing duration as needed
Monitor and control preform eccentricity, especially post-heating
Use thermal protection to limit deformation
Boost Your PET Bottle Quality
By proactively resolving these common PET blow molding issues, manufacturers can achieve superior product consistency and operational efficiency. Whether you’re troubleshooting current problems or looking to upgrade your production line, our team offers expert guidance and robust mold solutions designed to meet the highest performance standards. Reach out today to see how we can support your production goals.