How Does Injection Moulding Work?


The injection moulding process involves the movement of […]

The injection moulding process involves the movement of plastic pellets through a heated screw and barrel to melt the plastic to a molten state. The screw and barrel on an injection moulding machine is similar to an auger arrangement where the material is pushed forward while the screw is rotating.

The screw position inside the barrel is forced backwards during the rotation by the plastic "shot" that builds up in front of screw. When the required shot weight in the barrel is reached, the rotation stops.

The next part of the process is where the molten plastic is injected into an enclosed die that has the shape of the finished plastic product. When the die is full with plastic it is allowed to cool.

While the plastic product is cooling, the next shot is processed through the barrel.Once cooling is finished, the mould opens up and the finished plastic product is ejected, before the tool closes to begin the process again. The time that it takes to process the raw plastic through the barrel, inject into the enclosed tool and eject the product is called the cycle time.

The total cycle time of a plastic product will be determined by several different factors such as product thickness, where thicker components will take longer to cool, and the overall sizes, which can influence the time taken to fill the mould with plastic Items that are produced from injection moulding can include food packaging products such as cutlery, plates, lids and containers, and other products such as caps, clothes pegs, kids toys.