Plastic Injection Moulding means Injecting the Molten material into the desired mould to get the finished product.
With plastic injection moulding, granular plastic is fed by a forced ram from a hopper into a heated barrel. As the granules are slowly moved forward by a screw-type plunger, the plastic is forced into a heated chamber, where it is melted. As the plunger advances, the melted plastic is forced through a nozzle that rests against the mould, allowing it to enter the mould cavity through a gate and runner system. The mould remains cold so the plastic solidifies almost as soon as the mould is filled. It is most commonly used to process both thermoplastic and thermosetting polymers.
Thermoplastics are prevalent due to characteristics which make them highly suitable for plastic injection moulding, such as the ease with which they may be recycled, their versatility allowing them to be used in a wide variety of applications,and their ability to soften and flow upon heating. Thermoplastics also have an element of safety over thermosets; if a thermosetting polymer is not ejected from the injection barrel in a timely manner, chemical crosslinking may occur causing the screw and check valves to seize and potentially damaging the injection moulding machine.