Cast rotor and method

A method for forming a rotor assembly including a rotor core and a cast winding, the method including:

• heating a rotor core to a minimum temperature, wherein the rotor core includes a plurality of generally longitudinal passages;
• positioning the heated rotor core in a mold cavity such that each of the plurality of passages is in fluid communication with the mold cavity;
• wherein the mold cavity and the plurality of passages define a rotor winding including a plurality of conductor bars;
• quiescently flowing molten metal through a ring-type ingate and simultaneously into each of the plurality of passages prior to flowing molten metal into a mold portion to form at least one of a first end ring and a second end ring,
• wherein the flow of molten metal displaces impurities from the plurality of passages;
• pressurizing the molten metal during solidification to reduce shrinkage porosity in the winding;
• and
• solidifying the molten metal to form the winding.

A rotor assembly comprising:

• a rotor core and a rotor frame;
• wherein the rotor frame comprises a single casting made of an electric grade alloy, the rotor frame including:
• a first end ring;
• a second end ring;
• a plurality of conductor bars;
• and
• wherein each of the plurality of conductor bars is characterized by negligible porosity.