The surface of a part or product strongly influences its properties and functions. These are, e.g., abrasion and corrosion resistance, insensitivity to scratches, haptics as well as the visual impression to the customer. Therefore, many plastic parts have structured surfaces like leather textures on car dashboards. Usually these structures are integrated in the injection mould for the production of the plastic parts and then transferred to the plastic parts during the injection moulding process. A new approach to structuring metallic surfaces with laser radiation is structuring by remelting. Another approach of enhancing the appearance of design surfaces is creating a two-gloss effect by selective laser polishing. Both laser-based processes are based on reallocation of material instead of ablation

A new approach to polish metallic freeform surfaces is polishing by means of laser radiation. In this technology 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. As the typical processing time is 1 min/cm² laser polishing is up to 30 times faster than manual polishing. Reducing the roughness by laser polishing is achieved for several different materials such as hot work steels for the die and molding industries or titanium alloys for medical engineering. Enhancing the appearance of design surfaces is achieved by creating a dual-gloss effect by selective laser polishing (SLP). In comparison to conventional polishing processes laser polishing opens up the possibility of selective processing of small areas (< 0.1 mm²). A dual-gloss effect is based on a space-resolved change in surface roughness. In comparison to the initial surface the roughness of the laser polished surface is reduced significantly up to spatial wavelengths of 80 microns and therefore the gloss is raised considerably. The surface roughness is investigated by a spectral analysis which is achieved by a discrete convolution of the surface profile with a Gaussian loaded function. The surfaces roughness is split into discrete wavelength intervals and can be evaluated and optimized. Laser polishing is carried out by using a special tailored five-axis mechanical handling system, combined with a three axis laser scanning system and a fibre laser.

Surface structuring by remelting with laser radiation is a new approach to shape metallic surfaces (“WaveShape”). In this structuring process, surface material is reallocated in its molten state instead of being removed, because the process is based on the new active principle of remelting. The surface structure and the microroughness result from a laser-controlled melt pool due to surface tension. Basic research has been conducted with promising results, especially for the hot work steel 1.2343. Since remelting is a thermally driven process, significant differences between metallic materials were expected due to their thermophysical properties such as thermal conductivity, absorption coefficient, viscosity, heat capacity, etc. Therefore, the presented research soughed to expand the spectrum of processable materials. Within the framework of our investigation, we compared the achieved structure height as well as melt pool dimensions for six different materials. Furthermore, we successfully tested new structuring strategies such as not linearly shaped scanning vectors to create innovative surface structures on all materials investigated. The biggest structures were achieved on the titanium alloy Ti6Al4V and the nickel based super alloy IN718. Finally, an approach of reverse structuring was investigated in order to erase existing structures and achieve a smoothed rewriteable metallic surface. The results show that surface structuring by laser remelting is well suited to process a wide range of different metals and to achieve a broad variety of different structures as well as to effectively erase existing surface structures such as milling marks.

Recent results of processing fused silica using a high-power $Q$-switched ${\mathrm{CO}}_2$ laser source with a maximum output power of 200 W are presented. Compared to the processing with continuous wave laser radiation, the main advantage of pulsed laser radiation is the influence of the light–matter interaction with high laser peak power at small average laser power. An application for the approach presented in this paper is the flexible manufacturing and form correction of optics. This laser-based process is nearly independent of the surface geometry and can even be enhanced by laser polishing and expanded to other glass materials. Hence, the high-power $Q$-switched ${\mathrm{CO}}_2$ laser source is used to ablate glass material with an ablation rate up to $2.35{\mathrm{mm}}^3/\mathrm{s}$ and also for ablating glass material locally in a vertical dimension down to 3 nm.