To assist with easy automatic coil insertion the winding slots are made the full width throughout, but to limit magnetic noise, ripple and cogging effects it is desirable to employ closed or semi-closed slots. Both requirements are achieved by dimensioning the tooth tips such that, after coil insertion, the tips can be deformed to the required shape. The tip deformation may be carried out by a variety of cold forming methods, for example rolling or pressing. As well as giving the required magnetic effects, the deformed tooth tips can also be made to retain the coils in the slots. The technique can be employed on both stators and rotors. The application is mainly to small size machines, for example alternators for vehicles.
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