Copper motor rotors: Energy saving efficiency, now also economic feasibility

Replacing aluminum with copper in the die cast squirrel cage conductor bars in electric induction motor rotors has enormous potential benefit in terms of improved efficiency, energy savings, reduced maintenance and reduced weight and cost. Energy savings in the US alone can eventually exceed the output of three to four new 600 megawatt generating plants. The major deterrent to that conversion has been the short tool life associated with casting molten copper. Research sponsored by the Copper Development Association has identified recommended tool materials and casting practices that significantly improve tool life. THT Presses, Inc. has developed a vertical die casting machine with design features especially suitable for casting motor rotors, and have demonstrated capability to cast a wide range of copper motor sizes on that equipment. They now cast copper-alloy motor rotors for customer evaluation and for limited-volume production runs. THT's Sub Liquidus rheocasting process provides future opportunity for even better tool life when die casting copper alloys.