Spinning mold method for making permanent magnets

Abstract

A method is described for producing permanent magnets, in accordance with which magnetic material in finely divided or powdered form, comprising an alloy of a rare earth metal and cobalt, is first premagnetized by subjecting it to a high-intensity magnetic field to magnetize the individual particles thereof, the particles are then introduced into a hardenable resinous material and caused to be distributed substantially uniformly throughout at least a region of said resinous material. While said particles are being introduced into and distributed throughout said resinous material, they are subjected to a magnetic field to align them magnetically. The resinous material is then hardened to form a body thereof in which said particles are maintained in magnetic alignment to form an effective permanent magnet structure. In preferred forms of the invention, fibrous material and/or fiberglass cloth or mat may be embedded in the matrix to enhance its strength. In addition, an auxiliary magnetizing coil may be embedded in the matrix for modulating the effective magnetic field of the permanent magnet on a temporary basis. Practice of the method permits the production of superior permanent magnets which may be of relatively large size compared to those producible in accordance with the methods of the prior art and whose resistivity may be controlled to adapt them for various applications such as use in magnetic bearings.