Injection blow moulding is a process used to make hollow products, such as drinks bottles, in large quantities.  

The process is divided in to three stages, injection, blowing and ejection. 

Injection Stage  Molten polymer is injected into a heated preform mould.  The preform is the partly shaped product that will be used to make the final hollow product by being blown into shape.  The preform consists of a fully formed neck with a thick tube of polymer attached.

Blowing Stage  The preform is passed to the hollow, chilled blow mould. Compressed air is blown through the core rod into the preform material, inflating it and forcing it against the sides of the mould.

Ejection  The blow formed polymer is allowed to cool.  It is then removed from the blow mould and stripped off the core rod.  The product then passes to the quality control section and is tested for leaks.