11.3 Polishing with Laser Radiation

The surface roughness of a part or product strongly influences its properties and functions. Among these can be counted abrasion and corrosion resistance, tribological properties, optical properties, haptics as well as the visual impression the customer desires. Therefore, in industrial manufacturing grinding and polishing techniques are widely used to reduce the roughness of surfaces. A new method to attain such high-quality surfaces is polishing with laser radiation. In principle there are three different process variants [19]. At the top of Fig. 11.23 a sketch of a cross-section of a milled surface is shown. With polishing by large-area ablationmaterial is ablated over the whole surface. Thereby, the smoothing is achieved by increased ablation of the peaks of the surface and decreased ablation in the valleys. In contrast, polishing by localized ablation requires a precise measurement device for measuring the initial surface profile. After a nominal/actual value comparison only the peaks of the profile are ablated by a controlled laser pattern. The third process variant is polishing by remelting. A thin surface layer is molten and the surface tension leads to a material flow from the peaks to the valleys. No material is removed but reallocated while molten. In the following, further details are shown for all three process variants [63].