A suitable machine must be defined for each injection-moulded part for the component to be produced in a qualitative and economically optimal manner.
Here, the most important characteristic is the clamping force, which is specified in kilonewtons (kN) or colloquially referred to as tonnes (10 kN correspond to approximately a weight of 1 tonne). The clamping force ensures that the injection mould remains closed during the injection phase and the holding pressure phase and prevents the forming of flash or fluctuations in thickness of the article. A decisive factor for the determination of the required clamping force are the projected surface of the article (in the direction of demoulding) and the pressure of the plastic melt in the mould. The largest injection moulding machine at H+K has a clamping force of 500 tonnes. The maximum projected surface approximately corresponds to the size of a sheet of A4 paper, under optimal conditions even A3.
An additional characteristic is the size of the injection unit. The injection unit must be capable of melting the required amount of plastic granulate and to build up sufficient pressure to be able to fill the mould with the melt. Then again, the volume of the injection unit may not be too large, as the melt could otherwise be damaged thermally. For a performance that is always optimal, we have machines with differently dimensioned injection units, also within a machine group. Article weights between a maximum of 3,500 g and down to 0.1 g can be realised with this (see also: Micro injection moulding).