Process- and material-induced surface structures during laser polishing

Laser polishing is a technique for smoothing the surface of metallic substrates. The roughness after polishing does not only contain remains of the initial surface roughness, it also contains new roughness due to surface structures, which are introduced by the polishing process. Since these structures greatly contribute to the roughness, it is necessary to understand the mechanisms that lead to their formation so as to prevent the structures from forming and allow higher smoothing of the surface. Hence, in this publication it is investigated experimentally and numerically why these structures occur, what the influencing parameters are and how their influence on the roughness can be reduced, for both laser macro and laser micro polishing. It could be seen that the structures are influenced by the process parameters and the material of the workpiece. For a low surface roughness, the process parameters have to be adapted antithetically in some cases which means that it is not possible to prevent all structures at the same time and that surface structures will always occur during laser polishing. The process parameters must be adapted in such a way that all structures together lead to a surface roughness as low as possible.