Increasing Productivity of Ultrashort Pulsed Laser Ablation in Advance for a Combination Process with ns-laser

The most common way to create surface functionality in mass production are replication processes via structured mold tools. Currently used manufacturing processes for tool structuring like photo-chemical etching are limited in precision and in flexibility. A new and promising approach is to combine nanosecond (ns) and picosecond (ps) pulsed laser ablation sequentially to a hybrid process-similar to mechanical roughing and finishing process. However, one of the main drawbacks is the low productivity of the ps process that significantly determines the productivity of the whole combined process. To overcome the above-mentioned drawback, we investigate ultrashort pulsed laser processing using pulse bursts and varying pulse durations. By reducing the pulse duration from 10 ps to 900 fs the productivity gets doubled without any negative impact on the surface quality. Using average powers of more than 70 W an ablation rate of up to 13 mm³/min is achieved. Not only productivity benefits from burst processing, but also the surface quality gets significantly improved. The roughness of a ns pre-structured surface improves from Ra = 1.40 μm to Ra = 0.54 μm.