An apparatus or assembly for forming injection molded magnets in permanent magnet rotors or laminations for such rotors. The assembly includes a plurality of platens defining an axial boundary of a die cavity and a plurality of support shoes that are radially moveable between a closed position defining a radial boundary of the die cavity, and an open position creating a gap between the rotor core and the plurality of support shoes. The assembly has an injection system for filling at least one of the plurality of voids of the rotor core with a magnetic slurry, and a plurality of alignment magnets configured to magnetically align the magnetic slurry.