Blow Moulding

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.

Injection-blow moulding is the best processing choice for producing the highest quality plastic bottle containers that consistently meet close tolerance pharmaceutical specifications. Our Blow moulded products have a high accuracy in the neck finish, and minimal variations in weight, wall thickness, and volume.

Important factors to make high-quality bottles at good production rates include:

• The right preform and bottle designs
• The right grade of PET resin
• Good injection molding practices, to make high-quality preforms
• The correct temperature profile of the preform before blow molding
• The correct timing for stretch, pre-blow and blow
• Equipment and molds in good operating condition
• Adequate auxiliary services such as compressed air and chilled water