Injection Moulding Cycle

A typical sequence of Injection moulding cycle is as following

1; Starting with an empty cylinder, raw material from the feed hopper falls onto the rear
flights of the screw which takes material into the front of the cylinder. During its
passage along the cylinder it is plasticised to a fluid state with the help of external
heaters on the cylinder. Some material may escape through the nozzle but the back
pressure is generally sufficient to push the screw back in the cylinder and to provide a
holder for fluid plastic in the front of the cylinder for injection.

2; The mould closes and the cylinder moves forward on its way until the nozzle is in
contact with the mould access way.


3; The screw is moved forward by the hydraulic cylinder and the injection takes place.


4; After a short interval of time the screw rotates, creating some pressure in
the barrel, which forces it back against low pressure in the hydraulic cylinder, until
the limit switch operates, stopping the rotation. This plasticizes material ready for the
next shot.
5; The mould opens, the article is ejected and the mould closes again ready for the next
cycle.