Laser hardening is often used for hardening component segments that are subject to high wear. With this method, segments irradiated by the laser can locally be hardened, as well as the selective processing of three-dimensional and irregular work pieces. Unnecessary rework and delays are avoided; in addition, there is a time saving since only part of the tool has to be heated. This boundary layer processing method is used with ferrous components such as steel und cast iron with carbon content.
The material is heated above the austenitising temperature with the laser for a short time. With the further movement of the laser beam, the surrounding material quickly cools the hot layer. The so-called self-quenching occurs by conducting heat into the interior of the material. The rapid cooling creates martensite, a very hard metal structure, which leads to the increase in hardness.
In the process of laser hardening, relatively low power densities are used. The smaller the areas for laser hardening and the lower the required hardness depth, the more efficient the process. The laser beam is designed in a way to irradiate the largest possible area. For this, scanner optics are also used.