Dynamic control of laser beam shape for heat treatment

One of the major challenges for laser hardening is dealing with the geometrical singularities of the treated components. The problem arises from the laser hardening of uneven surfaces such as those with sharp edges or holes. In these cases, due to the differences in the surrounding volume of the material, overheating problems often appear leading to unacceptable treatment results. Despite several works tackling the problem of achieving uniform transformation profiles, the problem of the design and control of a beam delivery strategy leading to a desired transformation profile in the general case is considered to remain a true technical challenge. The main goal of this work is to present the control software developed by Talens Systems, which allows a customized laser beam delivery, providing different energy density patterns. By modifying these patterns in real time by means of scanning optics, the beam shape is able to adapt to almost any part geometry with full control of energy density, avoiding undesirable overheating effects. In addition, thanks to the modulation of the laser power and the changing speed of the scanning mirrors, the ability to “dodge” certain areas is possible and presents itself as one of the most interesting skills from the dynamic optical system shown in the present work. As an example of the success of this technology, automotive pieces have already been satisfactorily heat treated, meeting specific depth and hardness requirements. The developed knowledge and methodology could find applications in other laser processes such as cladding, welding, remelting, and alloying.