Patent ID: RE40524

Claim:
A An isotropic, resin-bonded rare earth magnet substantially composed of an R—T—B alloy powder, wherein R is at least one rare earth element including Y, and T is Fe or Fe+Co, and a binder resin, said R—T—B alloy powder comprising an R 2 T 14 B -type intermetallic compound as a main phase and having an average crystal grain size of 0.01-0.5 μm, and wherein said resin bonded rare earth magnet is in the shape of a ring having a radial thickness of 0.3-3 mm and a length of 50 mm or less, the a deviation of an outer periphery of said resin-bonded rare earth magnet from a circle being 10 μm or less in said radial thickness of 0.3-3 mm along the circularity of an outer diameter of 50 mm or less, said resin-bonded rare earth magnet having two end portions and a center portion therebetween along the length thereof and having a density of 6.0 g/cm 3 or more with a density distribution showing higher density in the two end portions than in the center portion between the two end portions of the resin-bonded rare earth magnet, the difference between the highest density in the two end portions and the lowest density in the center portion being 0.3 g/cm 3 or less, said resin-bonded rare earth magnet having a (BH) max of 10.5 MGOe or more greater than about 10 . 1 MGOe, and said resin- bonded rare earth magnet being produced by a compression molding method .