Abstract: The present invention provides a method and apparatus for die-casting copper and other metals that are cost-effective and practical for production use in die-casting, for example, copper motor rotors. In motor rotors, the incorporation of die-cast copper for conductor bars and end rings in place of aluminum is known to result in improvements in motor energy efficiency. Previous attempts to die-cast copper motor rotors in a commercially feasible manner have failed because copper's high melting point places too great a stress on the die material, resulting in cracking and fracturing of the molds. High temperature die materials such as nickel, tungsten and molybdenum based alloys with a high melting point are employed, and a die casting apparatus is provided to pre-heat the molds prior to injection of the molten copper. Pre-heating and high operating temperatures provide extended die life.

Abstract: The present invention provides a method and apparatus for die-casting copper and other metals that are cost-effective and practical for production use in die-casting, for example, copper motor rotors. In motor rotors, the incorporation of die-cast copper for conductor bars and end rings in place of aluminum is known to result in improvements in motor energy efficiency. Previous attempts to die-cast copper motor rotors in a commercially feasible manner have failed because copper's high melting point places too great a stress on the die material, resulting in cracking and fracturing of the molds. High temperature die materials such as nickel, tungsten and molybdenum based alloys with a high melting point are employed, and a die casting apparatus is provided to pre-heat the molds prior to injection of the molten copper. Pre-heating and high operating temperatures provide extended die life.