The rotors and stators are the core components of electric motors. Generally, the motor laminations form the core of the stator and rotor. They consist of thin metal sheets that are stacked, welded, or bonded together. By making them from individual pieces of metal rather than a solid pieces, they experience less eddy current losses.
Thin metal laminations are used to minimize the eddy current loss in the stator cores of high-speed, high-performance induction motors. The conventional fabrication technique, however, introduces limitations on the thickness of laminations, the dimensional accuracy of the assembled stator cores, and the production economy. These limitations greatly hamper the application of high-speed induction motors in industry.
The manufacturing process starts with cold-rolling the silicon iron mto the required thickness for lamination sheets. For high frequency applications, the least core loss can be obtained by using very thin lamination sheets, usually of 0.1-0.17 mm in thickness. An insulation coating is then applied to the lamination sheet to prevent eddy currents from traveling between the sheets. After that, the lamination sheets are shaped by the stamping process in either a progress or a single station die. Then the sheets are stacked on an aligning fixture and pinned or welded together to produce the magnetic cores. Because the stamping process introduces burrs and stress around the edges, some post-machining and heat treating are performed to obtain maximum core performance.