Pulsed laser machining of high-performance engineering and biomedical alloys

The exceptional mechanical and thermal properties of high-performance engineering and biomedical alloys lead to difficulties in machining with conventional processes. This work explores nanosecond pulsed laser machining as a flexible alternative to overcome manufacturing-related limitations associated with Ni Hastelloy, Ti-6Al-4V titanium alloy and Stellite 6K. An extensive experimental campaign was performed with a 1064 nm nanosecond pulsed fibre laser, quantifying the ablation threshold, penetration depth and material removal rate as functions of average laser power (2 to 20 W), repetition rate (20 to 80 kHz), scanning velocity (100 to 2,000 mm/s) and number of laser passes (1 to 20). Optimum conditions for machining were achieved for all alloys with 20 W average power, 20 kHz repetition rate and 1,000 mm/s scanning velocity due to strong ejection of the liquid phase with high pulse fluence (71 J/cm2), good process stability and material removal rates in the range 0.08 to 0.17 mm3/s.