Start
PET Resin
Preform molding
Preform design
Preform Animation
Blow Molding
Bottle Design
Reheat stretch blow machinery
Single stage machinery
One stage vs. two stage machinery
For both one-stage and two-stage blow molding processes, a hot preform is clamped in a blow mold. A stretch rod is usually used to stretch the preform to the base of the mold, while low pressure compressed air is used to “pre-blow” the preform into a bubble. Then high pressure air is applied to push the PET bubble into all the details of the blow mold, and to cool the newly-made bottle. Time is allotted in the cycle to depressurize the mold before opening it and removing the bottle.
The little graphic above is a reasonable but not exact representation of how the preform inflates.
Important factors to make high-quality bottles at good production rates include: