The injection moulding method is suitable for the thermoplastics resins:-

This is used for high speed moulding of thermoplastics. The moulding composition is heated in a suitable chamber connected by a duct leading to the mould. The hot softened molten plastic is injected at a controlled rate into the tightly locked mould by means of a screw or a piston plunger. The mould is kept cold to allow the hot plastic to cure and became rigid. When the material is cured sufficiently, half of the mould is opened to allow the ejection of the finished article.

Drawback of this method is a large number of cavities cannot be filled simultaneously. The temperature used is $90o-260o$ and pressure used is $100-500 kg/cm2cm2.$