Induction Hardening Treatment for Your Components

Induction hardening is a very widely used industrial process for the surface hardening of steel. The steel components to be hardened are heated by means of an alternating magnetic field to a temperature within or above their transformation range. This heating process is then reversed by immediate quenching or rapidly cooling down the metal components to room temperature. Just as with case hardening or face hardening the core of the metal, the component remains unaffected by the treatment and its physical properties and advantages are unaffected too. But it is now sheathed in a much harder alloy that has a higher carbon content.

The process requires a source of high frequency electricity that is used to drive a large alternating current through a coil. The passage of current through this coil generates a very intense magnetic field that is rapidly changing in its polarity in the space within the coil. The metal component that is to be hardened is inserted into this rapidly alternating magnetic field and the current generated within the object itself rapidly heats it up. This hardening results in a layer of a highly wear resistant alloy around the component. This makes these sort of metal pieces used widely in automotive and industrial applications where long life and wear resistance are required.

There are two primary types of hardening. Single shot or static hardening is the process where the component is contained within the coil in its entirety and either held static or rotated. The hardening effect is achieved all over the surface of the object simultaneously. The advantage is a quicker process due to the fact that the entire component is being treated in one go itself. The quenching process or the cooling down is also done at one go for the entire component. The drawback is the higher power requirement of the induction coil required for the hardening process.

Traverse hardening is the other type of induction hardening process widely used for long components like axle shafts and steering columns for automotive applications. The induction is actually done by a ring type inductor that creates a band of heat that needs to be moved along the length of the component. The quenching process is also done in a similar manner. The advantage is that less power is required and by varying the speed of the ring variable hardening is achievable. The drawback is the additional time taken per component.