Applications of rare-earth magnets to the small motor industry

The usage of high-performance rare-earth magnets is one of the key technologies in the development of efficient small motors. Up to the present, ring-shaped melt-spun Nd-Fe-B bonded magnets prepared by the powder compacting press and/or the injection molding are generally used in typical applications to small efficient motors. For drawing out the maximum characteristics according to a variety of magnetic powder, however, we need to change the preparation method of a magnet, the magnet form, and the motor design for high-productivity as well as to improve total performance including magnetic properties of bonded magnets. This contribution reviews our recent achievement on new preparation processes for rare-earth bonded magnets and small motors using the new materials other than Nd-Fe-B melt-spun powder. Especially, the method of drawing out the maximum characteristics of some kinds of magnetic powder is proposed. In addition, this report describes the investigation of the application trend and topics of rare-earth bonded magnets for highly-efficient small motors in the small motor industry.