A selective hardening process in which a coil induces current that heats the tooth surface in seconds, followed by a water-polymer quench. Small gears are spin hardened all at once, while large gears are hardened tooth by tooth or gap by gap with a shaped inductor. The hardened pattern matters: a contour pattern that runs through the root gives bending strength, while a flank-only pattern can leave the root weaker than before.
Induction hardening pattern has to wrap the root, a flank-only pattern on this girth gear is asking for broken teeth.
Also heard as
- induction hardened
- IH
Related terms
Case depth
How deep the hardened surface layer of a gear tooth goes, usually measured to a set hardness such as 50 HRC.
Carburizing
A heat treatment that diffuses carbon into the surface of low-carbon steel gears, then quenches for a hard case.
Tooth breakage
A gear tooth cracking off, most often by bending fatigue starting in the root fillet on the loaded side.