Equipment Selection for Induction Hardening: Single-Shot Hardening – Part 1

With the single-shot method, neither the workpiece (cylinder shaft, for example) nor the coil moves linearly relative to each other; the part typically rotates instead. The entire region that is to be hardened is heated all at once rather than only a short distance, as is done with scan hardening.

With conventional scan hardening of cylindrical parts, induced eddy currents flow circumferentially. In contrast, a single-shot inductor induces eddy currents that primarily flow along the length of the part. An exception to this rule would be the half-moon regions (also called the crossover or bridge sections) of a single-shot inductor, where eddy current flow is circumferential.

Normally the single-shot method is better suited for hardening stepped parts where a relatively short (1.5–2 in. [38–50mm] long heated area is commonly minimum) or moderate length area is to be heat treated. This method is also better suited to cylindrical parts having axial symmetry and complex geometry including various diameters.

To read the rest of Dr. Valery Rudnev’s article on Equipment Selection for Induction Hardening, please visit HeatTreatToday.com.