A method of assembling and manufacturing a laminated rotor is provided which uses laminations having a thin bridge thickness. Different techniques are provided for preventing the molten material used in the casting or injection molding operation from leaking or seeping between the laminations during casting. In one technique, the laminations are stacked and oriented in the conventional way, and then both axial and radial pressures are applied to the stacked laminations to hold the laminations in position for the casting process. In another technique, the laminations are formed or extruded with a lip or collar portion that fit in a countersunk portion of an adjacent lamination and forms a wall or barrier between the laminations to prevent the leakage of the molten material during the casting or injection molding operation.