On the pulsed laser ablation of polycrystalline cubic boron nitride—Influence of pulse duration and material properties on ablation characteristics

Polycrystalline cubic boron nitride (PCBN) is widely used in industry as a cutting tool material for the machining of hardened steels, cast iron, or nickel-based super alloys. For the generation of geometrical features on such cutting tools, laser ablation is a novel and promising technology, which offers wear-free processing, high automation potential, and geometrical flexibility. In this study, the ablation mechanisms are experimentally investigated for a wide range of laser pulse durations (fs–ns regime), and the effects on ablation depth, ablation efficiency, and surface roughness are investigated. It is shown that melting and recrystallization of binder material when processing with nanosecond pulse duration leads to a reduction of the ablation efficiency and reduced surface quality. These defects can be avoided by using a shorter pulse duration (picosecond and femtosecond). The highest ablation efficiency is achieved for femtosecond laser ablation. Moreover, fs-laser processing shows beneficial behavior in the ablation of coarse-grained PCBN grades, where grain excavation due to binder removal is prevented and the resulting surface roughness is significantly decreased compared to ns-laser processing.