Laser polishing of metallic freeform surfaces

As a new approach for automated polishing of metallic freeform surfaces, laser polishing could support or replace time-consuming and cost intensive manual polishing in the near future. This new technique is based on using laser radiation to remelt a thin surface layer. Due to the surface tension, material flows from the peaks to the valleys, thus causing the surface to resolidify, smoothed. To assess laser polishing of freeform surfaces, the Fraunhofer Institute for Laser Technology has developed and tested two industrial polishing machine tools and a continuous CAM-NC-data chain. This new polishing technology could be applied in any field where metallic surfaces have to be polished to a medium quality (Ra=0.1-0.5 µm). Initial industrial applications for laser polishing already exist in the automotive industry and in mold making. Several different materials can be polished with laser radiation: for example, hot work steels for the die and molding industries or titanium alloys for medical engineering. This paper provides an overview on the development of the laser polishing technique over the last 10 years at the Fraunhofer Institute for Laser Technology.