Abstract: This invention provides methods for rapidly heating a metal part of varying thickness. In general, the invention provides methods comprising heating the thicker section(s) of the part by induction heating and the thinner section(s) by resistance heating. Induction and resistance heating both quickly heat metals and because each is easily controlled individually, the part can be uniformly heated for hardening and tempering.

Abstract: An improved induction melting coil apparatus encapsulated with homogeneous inserts for controlling the direction of inductor flux density is disclosed. The inserts are relatively thick and rigid members which provide a low reluctance path within which the magnetic field travels while inhibiting inductive coupling of the magnetic field with surrounding auxiliary components. The inserts can be easily formed or machined into any desired shape for effectively encapsulating virtually any type of coreless induction melting coil.

Abstract: An improved induction melting coil apparatus encapsulated with homogeneous inserts for controlling the direction of inductor flux density is disclosed. The inserts are relatively thick and rigid members which provide a low reluctance path within which the magnetic field travels while inhibiting inductive coupling of the magnetic field with surrounding auxiliary components. The inserts can be easily formed or machined into any desired shape for effectively encapsulating virtually any type of coreless induction melting coil.

Abstract: Disclosed are compositions useful in fabricating blocks or inserts for inductors comprising:(a) about 98 percent to about 99.5 percent by weight of a high purity, annealed electrolytically prepared iron powder; and(b) about 0.5 percent to about 2 percent of an insulating polymer binder selected from the group consisting of epoxies, flourocarbon, hot melt adhesives, and mixtures thereof;wherein said iron powder has a specific surface area of less than about 0.25 m.sup.2 /g and a carbon content of less than about 0.01 percent; andwherein said composition after pressing at at least about 30 Tsi demonstrates a maximum of 5 percent regression in permeability and a total core loss of less than about 0.8 to about 1.2 ohms between 10 KHz and 500 KHz. Blocks and inserts made from such compositions, as well as methods of manufacturing such inserts, are also disclosed.

Abstract: A new inductor, coating, and method adapted to improve the directional control of magnetic flux of an inductor. The method may include using a fluidized bed or other like methods to coat an appropriately masked inductor with a coating composition comprised of a low reluctance material and a binder. The low reluctance material in the coating composition may include such materials as carbonyl iron powder or the like, whereas the binder may comprise a polymeric resin or the like. The present coating composition increases the directional control of magnetic flux, and efficiency of the inductor by selectively distorting the magnetic field and thereby increasing and intensifying the flux density on a subject workpiece being induction heated. The invention is also believed to be usable in improving directional control of magnetic flux in other electrical conductors.