1.
The mould closes and is held closed with a force of up to several hundred tonnes, depending on the size of the moulding machine. This high pressure counteracts the hydraulic pressure attempting to force the mould open when the molten plastic is injected. Larger moulded parts require larger machines to hold the mould closed.
2.
Molten plastic is injected into the mould tool. Injection pressures can be as high as 20,000 psi, approximately 9 tonnes per square inch.
3.
The part is left to cool, and during this time, the screw rotates and forces molten material to the front of the screw, ready for the next injection cycle.
4.
Once the part has cooled and solidified, the mould opens, and the part is ejected. The cycle then begins again.
