Laser milling: pulse duration effects on surface integrity

Laser milling of engineering materials is a viable alternative to conventional methods for machining complex microcomponents. The laser source employed to perform such microstructuring has a direct impact on achievable surface integrity. At the same time, the trade-offs between high removal rates and the resulting surface integrity should be taken into account when selecting the most appropriate ablation regime for performing laser milling. In this paper the effects of pulse duration on surface quality and material microstructure are investigated when ablating a material commonly used for manufacturing microtooling inserts. For both micro- and nanosecond laser regimes, it was estimated that the heat-affected zone on the processed surface is within 50 mu m. When performing ultra-short pulsed laser ablation, the effects of heat transfer are not as evident as they are after processing with longer laser pulse durations. Although some heat is dissipated into the bulk when working in pico- and femtosecond regimes it is not sufficient to trigger significant structural changes.