A rotor casting includes a lamination stack and a cast structure including proximal and distal cast end rings respectively adjacent proximal and distal end faces of the lamination stack. Cast axial ribs are distributed radially on a peripheral surface of the lamination stack and extend between the proximal and distal cast end rings. Cast feed members extend axially from the proximal cast end ring and are respectively positioned radially between an adjacent pair of axial ribs. In one example, cast bar segments integral to the proximal and distal cast end rings are formed in axial slots of the lamination stack. In one example, a bar insert in each axial slot has insert ends that extend respectively from the proximal and distal end faces of the lamination stack and are fully encapsulated respectively in the proximal and distal cast end rings. A method of forming the rotor casting is provided.