Tandem moulds increase the production capacity of an injection moulding machine thanks to their two mould parting surfaces. In contrast to stack moulds, the moulds are filled alternately in this case. The two mould parting surfaces can be seen as individual moulds which are independent from each other. The resulting advantage over stack moulds is that both moulds can have differing volumes and geometries, and the process chain can be optimised individually for each mould parting surface.
In the case of tandem moulds, the efficiency increase compared to individual moulds results from the cooling time of the one mould parting surface being used for the filling of the other. This not only increases productivity while the costs per unit decrease. The quality of the moulded parts also improves, because their cooling time becomes longer.