Blow Molding
2 views
PET Bottle Bottom Crater-Shaped Bulge
Problem Phenomenon
A ring-shaped or mound-shaped bulge appears around the injection point of the bottle bottom, affecting bottle standing and appearance, and in severe cases the bulge cracks and leaks.
Cause Analysis
The preform bottom temperature is low while other parts are too hot, and the bottom material accumulates during stretching; blowing timing too late, when the parison is already over-stretched to the bottom, also forms a bulge.
Solution
①Advance the blowing time and adjust the blowing timing; ②re-balance the temperature of each heating zone; ③appropriately raise the preform bottom temperature; ④check the stretch rod stroke setting.
Key Takeaway
The crater bulge is a manifestation of mismatch between bottom temperature and blowing timing; adjusting the heating curve and pre-blow timing can improve it, and standing stability needs to be verified after machine adjustment.; after confirming effectiveness, solidify the parameters and practices into the work instruction to prevent recurrence
Was this helpful?
0 people found this helpful
Thank you for your feedback!