Induction Hardening

In this procedure, a high frequency current of around 1000 to 10,000 hertz is passed through a copper inductor block which behaves as a primary coil of a transformer. The block is placed around but does not touch the surfaces to be hardened. The heating effect is because of the induced eddy current & hysteresis loss in the surface material. The hardening temperature is around 750^oC to 760^oC for 0.5% carbon steel and 790^oC to 800^oC for alloy steel. Then, the heated areas are quenched instant by sprays of water delivered through many small holes in the copper inductor block. Both of automatic and hand control might be employed. A depth of case of approximately 0.3 mm is attained in about 5 seconds, but in general hardened case of depth among 0.1 to 0.8 mm may be created by this method. This method is versatile and fast in varying hardness (by variation of current) and depth of hardness (by variation of frequency of current). It leaves clean surface without scale and need no further machining.