Recent developments in metal processing with pulsed laser technology

A microwave-excited pulsed oscillator-amplifier CO2 laser system is utilized for cutting experiments. This paper concentrates on cutting processes of aluminum sheets of 2, 4, 6 and 8 mm thickness with the option of variable laser pulse peak power and laser pulse duration. The quality of the cuts is judged by measuring the burr height and the surface roughness. The results of these measurements are correlated with absorption of a probing CO2 laser beam, which laterally passes the laser induced process surface plasma. Our experiments verify that the height of the absorption signals, which is a direct measure of the plasma development at the surface, is related to the burr height. On the other side, the burr height sensitively reacts to the 1% pulse duration with a characteristic minimum at τ1% ≈ 6.5 μs. By fast control of the 1% pulse duration under in situ diagnosed burr height (by the absorption signal) an optimized burr-free cutting is realized.