Induction Hardening

Induction hardening involves heat treating of metals, but there are several other kinds of hardening. The purpose is always to increase the strength of metals, and this occurs when heated metal is cooled rapidly. The result is a metal with small grains and increased resistance to penetration--hardness.

Chill hardening consists of placing metal pieces (chills) in the wall of a sand mold, so that the area next to the chill cools faster and becomes harder than the rest of the molded material. Hardening by precipitation involves chemical solutions and occurs at above room temperature. Should the cooling process happen at room temperature, it is called age-hardening.

Faster Results with Induction Hardening

Induction heating is fast--there is no warm-up period, no waiting until the desired temperature is reached. By sending an alternating current through a coil, a varying magnetic field is created, and an inserted part is immediately heated. Induction heating hardens the outer layer to the desired depth. This depth can be controlled by varying the power, frequency, and line speed. Induction hardening, especially if coupled with automation, results in increased productivity.

Annealing

Iron and carbon alloys, such as steel and cast iron, are well-suited to induction heat treating. The rate of cooling, together with the amount of carbon, produces many degrees of hardness. After induction hardening, and rapid cooling in water, oil, or molten salt, the metal can be further modified through annealing. Steel with a low carbon content can be given a hard exterior by increasing the surface carbon so the steel will react well to heat treating in the annealing process.