Process: Hot air is blown into a pre-formed tube, known as a parison, of semi-molten plastic. Under pressure from the blown air, the parison expands, like a balloon, to fill the cavity formed by a two-part, usually metal, mould. The tube is injection moulded allowing a thread for a lid or some other detail to be formed. Textures can be formed on the mould walls.
Introduced: 1881 for use with cellulose nitrate
Plastics: Commonly high density polyethylene and polyethylene terephthalate
Marks: An injection gate – see injection moulding.
Tooling cost: Relatively high
Production volume: High
Uses: Hollow articles, usually with openings of smaller diameter than the body, such as bottles or containers.