Patent ID: 8424188

Claim:
A method of manufacturing a rotor assembly for an electric device, the method comprising: stacking a plurality of laminated electric steel sheets to define a laminated stack having a first end surface and a second end surface axially spaced from the first end surface along a central axis, and a plurality of longitudinal grooves extending along the central axis between the first end surface and the second end surface, wherein the plurality of grooves are angularly spaced about and equidistant from the central axis; positioning one of a plurality of conductor bars in each of the plurality of longitudinal grooves such that a first end of each of the plurality of conductor bars extends outward beyond the first end surface of the laminated stack; positioning the laminated stack and the conductor bars in a mold having a first cavity that defines a first end ring; injecting liquid aluminum having a temperature greater than approximately six hundred sixty degrees Celsius (660° C.) into the first cavity of the mold; circulating the liquid aluminum within the first cavity and around the first ends of the conductor bars to heat the conductor bars to a temperature equal to or greater than approximately three hundred fifty degrees Celsius (350° C.) to reduce a bond strength between the conductor bars and any oxides formed on an outer surface of the conductor bars and to fracture any oxide films on the outer surface of the conductor bars; flushing the oxides away from the outer surface of the conductor bars with the circulating liquid aluminum; and cooling the liquid aluminum within the mold to form a first end ring over the first ends of the conductor bars.