押出成形Nd-Fe-B系ボンド磁石の開発

抄録

A new manufacturing process for extrusion molded magnets, composed of isotropic Nd-Fe-B powder and Nylon-12, has been developed. This newly developed extrusion molding process has several interesting features. First, the extruded product contains 72% by volume magnetic powder and yields a (BH)_max, of 8.0 MGOe. Second, through the addition of an anti-oxidant, the viscosity of the magnetic powder-nylon compound during molding remains almost constant. Third, by means of a specially cooled outlet, which is separated from the heated die by a thermal insulator, an optimized temperature profile is obtained which yields uniformly smooth extrusion molded magnets. Both long thin-walled magnets and small arc-shaped (“kawala”) magnets are easily molded by this new process.