Treating metal surfaces is usually carried out in induction hardening facilities using heat produced by induction. All relevant hardness and control parameters are automatically monitored in universal hardening systems. The desired degree of hardness can be set with the proper heating. In order to ensure a consistent level of quality, all process steps are continuously monitored. The surface treatment is carried out in part and in all kinds of metals. This can be, for example, the annealing and hardening of workpieces made of steel, cast iron or sintered metal. A specific inert gas procedure must be followed when components are hardened free from oxidation. Even large series can be hardened inexpensively using this procedure.