Abstract: Steel workpieces, such as thread-forming screws and bolts, tapping tools, and the like, are hardened in localized areas to controlled depths of hardening by utilizing loose electromagnetic coupling between the workpiece and the induction coil. The loose coupling reduces the criticality of the positional relationship between the workpiece and coil and also allows unidirectional axial through-feed of headed workpieces. A high degree of symmetry of hardening around each piece and uniformity of hardening from piece to piece at high production speeds is accomplished.

Abstract: A metal core printed circuit board which includes multiple layers of synthetic plastic resin material on a sheet of metal, and wherein the surface of the plastic material is of such character that it provides an acceptable bond on which are built up sundry layers of different metals, the innermost layer on the plastic surface and the other layers positioned one upon another, ultimately comprising a built up circuit pattern, and wherein areas intermediate the circuit pattern comprise an exposed surface of the resin material.