Laser Surface Texturing of Metals Using Dynamic Melt Expulsion by Application of Fast Modulated CW-Laser Radiation

Laser surface texturing of metals is usually performed using pulsed laser sources. Short and ultrashort pulsed laser systems offer the highest machining quality and processing flexibility. Most of these beam sources however feature relatively low average powers or high system prices. Continuous wave fiber lasers in comparison feature high average powers at moderate costs. In this work the laser power of a continuous-wave fiber laser is rapidly modulated to investigate the possibilities to improve laser surface texturing processes by periodically changing the interaction between the surface tension in the melt pool and the vapor pressure created during high power laser processing. It was found that the intermittent nature of modulated continuous wave laser radiation can improve the melt expulsion from the processing area, leading to high material removal rates and ablation efficiencies while also limiting the heat input into the substrate material. Keywords: surface texturing, modulated cw-laser radiation, melt expulsion, drilling, fast modulation, ablation efficiency, [micro]s pulses.