For economic reasons, the injection moulding process is best suited for plastic parts in standard sizes that are in high demand on the market. In this process, the granular starting material is given its final shape by being injected into a closed mould, which determines the geometry of the plastic part.

The advantages of the injection moulding process are

• Automated production
• Large series can be produced cost-effectively
• High quality standard

But how does the process actually work?

In principle, the injection moulding process consists of 6 individual steps. This is a so-called forming process with high precision of the manufactured parts.

1. Plasticising the granulate
   The plastic granulate is liquefied by heat in an elongated cylinder and homogenised by a rotating screw inside.
2. Injection of the liquefied plastic
   Plasticised plastic is injected into the closed injection mould at high pressure by pushing the screw very quickly in the direction of the mould and forcing the hot, liquid plastic through a channel into the mould cavity.
3. Pressing on during the cooling phase
   The screw remains in the front position until the hot plastic melt has solidified in the cooled mould. In this way, the shrinkage of the plastic caused by the cooling process is compensated for by the plastic being pressed into the mould. The injection mould is permanently cooled with water, but sometimes it is also brought to a certain temperature. This depends on the plastic to be processed. If the hot and liquid plastic then touches the cool mould wall, the plastic becomes solid again and the component thus retains its shape.
4. Dosing
   After holding pressure and during the cooling phase, the screw rotates again, building up a hot mass cushion that can be injected back into the closed mould during the next cycle.
5. Demoulding and start of a new cycle
   As soon as the plastic part has cooled down to form stability and shrinkage has ended, the mould can be opened and the plastic moulded part demoulded. In most cases, small ejector pins extend from the mould and push the plastic part out of recesses. The moulded part usually falls downwards into a basket or onto a conveyor belt. The mould is only open for a very short time, as a new production cycle begins when the mould is closed.