The stator core is made of 0.5mm thick silicon steel sheet laminated,and the two sides of the brick steel sheet are coated with insulating paint to insulate each other to reduce the core loss caused by rotatingmagnetic field in the stator core. The rotor core is generally composed of 0.5mm thick silicon steel sheets.The rotor core of medium and the small AC motors is mostly direcly installed on the motor shaft.The rotor core of the large AC motor in installed on the rotating bracket,and the bracket is covered on the rotating shaft.