Precise machining of disk shapes from thick metal substrates by femtosecond laser ablation

Femtosecond-pulsed lasers have proven to be versatile for machining of microscale features in a variety of materials with minimal residual stress and heat-affected zone. However, machining of components from 200-μm-thick metal substrates by femtosecond laser ablation requires repetitive scanning of the laser beam focus along multiple adjacent paths numerous times to completely remove the part. In this study, optimization of multi-pass ablation parameters for efficient cutting and optimum final shape accuracy of disks of Stellite, aluminum, and stainless steel was investigated. The ablation depth of Stellite was measured with different pulse energies and groove widths, and 200 μm of diameter and thickness of Stellite disk were machined. The tapered cross-section of the disk was observed and increased pulse energy as the laser beam approached the bottom of the sample helped to minimize the taper angle of the sides of the disk. Moreover, the comparison of ablation depth in Stellite, aluminum, and stainless steel were conducted with various pulse energies and groove widths.