A method of manufacturing an impeller, comprising machining hub, shroud and core portions, such that contacting surfaces between the hub and core, and shroud and core form mating surfaces, for mating and alignment with each other. Material is removed from the core without disturbing the contour of its surfaces, resulting in one or more vanes which mate with the respective hub and shroud portions. The mating portions are then coupled together.

The impeller made out of cast material in many cases may be called rotor, also. It is cheaper to cast the radial impeller right in the support it is fitted on, which is put in motion by the gearbox from an electric motor, combustion engine or by steam driven turbine. The rotor usually names both the spindle and the impeller when they are mounted by bolts.a