Which process uses a screw thread to force plastic into a mould where it cools and solidifies?

• A. Injection Moulding
• B. Vacuum Forming
• C. Blow Moulding
• D. Extrusion Moulding

Answer: (A)

Injection moulding uses a heated barrel with a screw that melts plastic pellets and then pushes the molten material into a closed mould under pressure. The mould is cooled so the plastic solidifies and the part is ejected. This screw-driven injection is the hallmark of the process and is ideal for making many precise, high-volume parts. The other methods operate differently: vacuum forming uses a heated sheet shaped by vacuum, blow moulding forms hollow shapes by blowing air into a heated plastic parison inside a mould, and extrusion produces continuous profiles by forcing molten plastic through a die rather than into a mould.