Patent ID: 8464777

Claim:
A method for forming a turbine or compressor wheel, the wheel having a hub and a plurality of blades of complex curvature extending outwardly from the hub, using a die assembly comprising an outer die and an inner die cartridge assembly, the method comprising the steps of assembling the inner die cartridge assembly from a plurality of die segments so that the inner die cartridge assembly defines and substantially encloses a central hub cavity and a plurality of blade cavities extending outwardly from the hub cavity, said blade cavities being defined between adjacent die segments, inserting the inner die cartridge assembly into the outer die, injecting a semi-solid metal alloy into the die assembly so that it flows into the cartridge assembly and blade cavities, maintaining temperature and pressure within the inner die cartridge assembly within predetermined ranges during the injection stage, removing the inner die cartridge assembly from the outer die and separating the die segments of the inner die cartridge assembly to release the formed wheel, wherein the alloy is injected via a runner passage in a runner block mounted on the outer die, the runner passage providing communication between an injection device and the central hub cavity, the runner block being moved to a first position after insertion of the inner die cartridge assembly so that it is positioned over the inner die cartridge assembly and secured to the outer die to support the inner die cartridge assembly and contain the effect of the pressure to which the semi-solid metal alloy is subjected in the inner die cartridge assembly and the runner block is moved to a second position in which it is clear of the inner die cartridge assembly after the injection step is complete so as to allow removal of the inner die cartridge assembly.