The big advantage of this system is its speed and ability to confine haeting on small parts. The major disadvantage is the cost. Water quenching is applied as soon as the transformation temperature is reached. The heating media can be oxygen acetylene, propane, or any other combination of fuel gases that will allow reasonable heating rates. This procedure is applied to the gear teeth, shear blades, cams, ways on the lathes, etc.
Flame is directed to the spot that needs to be heated and hardened.
They perform the same function as the flame in flame hardening or the induction coil in induction hardening. It is only appliacble to stels that have sufficient carbon and alloy content to allow quench hardening. The laser or electron bam is used to raise the surface temperature of the part. Electron Beam Hardening requires vacuum. Laser beam do not require vacuum and quenching can be done by using a gas.