LASER hardening of 3D complex parts: industrial applications and simulation results

Laser surface hardening of mechanical steel components is a rapidly developing manufacturing technology which allows to deal with small, confined and complex surfaces. It allows, in fact, to accurately focus the hardening treatment only where it is needed, without affecting the surrounding base material. This prerogative differentiates laser hardening from any other surface treatment, such as flame or induction, and makes possible to save time and energy during the process. On the other hand, when large surfaces have to be treated, the relatively small laser spot makes necessary to optimize new process strategies aimed at dealing with the inevitable tempering effect occurring when overlapping laser beam trajectories take place.According to these considerations the article analyzes the possibility to deal with large cylindrical surfaces, by means of laser surface hardening, exploiting the "apparent spot" technique. This solution applies on axisymmetric components and implies the combination of a rotation of the part to be treated and of the linear motion of the laser beam. In order to study the optimal process parameters involved in this technique a simulation analysis was carried out by means of a proprietary simulation software developed by the research group and a subsequent experimental campaign made possible to validate the whole procedure.