A Study on the Microstructural Defects in Slots of Thixoformed Copper Rotor
Cu-Ca alloys and the squirrel cage rotors for induction motors of small capacities were used for the development of thixoforming processes. Processing conditions, motor efficiency and forming defects in macro- and microscale for thixoforming of Cu-Ca rotors have been performed to investigate the microstructural features and the filling phenomena in slots of squirrel cage rotor. Inadequate filling due to the complexity of slot structure, separation of solidified metal from the slot, porosities and phase inhomogenitites were typical microstructural defects found in thixoformed Cu-Ca rotors. Exact flow control in terms of billet and die temperatures at slot gate especially, was necessary to prevent significant defects such as incomplete filling of slot.
C.G. Kang, S.K. Kim and S.Y. Lee
S. Y. Lee and S. Y. Lee, "A Study on the Microstructural Defects in Slots of Thixoformed Copper Rotor", Solid State Phenomena, Vols. 116-117, pp. 300-303, 2006