Patent ID: 8466395

Claim:
A method of induction heating one or more multiple features of a workpiece comprising the steps of: supplying electric power to at least one inductor to generate an ac magnetic field around the at least one inductor; sequentially positioning each one of the one or more multiple features of the workpiece in the vicinity of the magnetic field to magnetically couple the positioned feature to the magnetic field whereby the positioned feature is inductively heat treated; matching the impedance of the supply of electric power to the impedance of the workpiece; selectively varying the frequency of the electric power while each one of the one or more multiple features of the workpiece are sequentially positioned in the vicinity of the magnetic field; and selectively varying the magnitude of the electric power by changing the duty cycle of the electric power while each one of the one or more multiple features of the workpiece are sequentially positioned in the vicinity of the magnetic field and the frequency of the electric power is adjusted.