Blow moulding is described as which of the following?

• A. Process for making hollow plastic forms by injecting molten plastic into a die.
• B. Process for making hollow plastic forms by blowing air into heated thermoplastic.
• C. Creates simple hollow shapes by sucking a heated plastic over a mould.
• D. A process for creating large hollow plastic objects.

Answer: (B)

Blow moulding creates hollow plastic forms by inflating heated thermoplastic with air inside a mold. The plastic is softened by heat, placed in a mold, and air pressure expands it to fill the cavity, producing hollow shapes like bottles. This is different from injection moulding, where molten plastic is injected into a die to form the shape, and from vacuum forming, where heated plastic is drawn over a mold to form shallow profiles. The idea of blowing air into the heated plastic inside a mold best matches blow moulding. Variations include extrusion blow moulding and stretch blow moulding, but the core is the inflation of softened plastic to form hollow objects.