Patent ID: 8475610

Claim:
A method of induction heat treating a first portion of a gear, wherein a second portion of the gear remains untreated by induction heating, wherein the gear has an inner surface, wherein the first portion and the second portion are located along the inner surface of the gear, and wherein the first portion has a first width and the second portion has a second width, the method comprising: placing the gear within a workstation, wherein the workstation has a power source and an inductor coil, and wherein the inner surface of the gear is positioned to be proximate to the inductor coil, wherein the power source provides alternating current to the inductor coil, and wherein the inductor coil includes at least one heating loop and at least one non-heating loop, where the heating loop has a heating loop width and the non-heating loop has a non-heating loop width, and wherein the non-heating loop width is configured to be about equal to the second width of the second portion of the gear, and wherein the heating loop width is configured to be about equal to the first width of the first portion of the gear; rotating the gear about an axis of rotation, wherein the gear is rotated relative to the inductor coil; energizing the inductor coil to a predetermined frequency to create an alternating magnetic field, wherein the magnetic field developed in the heating loop induces an eddy current in the first portion of the gear; and maintaining the inductor coil at the predetermined frequency for a predetermined amount of time to induction harden the gear at the first portion.