Experimental study of cutting thick aluminum and steel with a chemical oxygen–iodine laser using an N2 or O2 gas assist

A chemical oxygen–iodine laser (COIL) was used to cut aluminum and carbon steel. Cut depths of 20 mm in aluminum and 41 mm in carbon steel were obtained using an N2 gas assist and 5–6 kW of power on target. The same laser at the same power level produced a cut depth of 65 mm in carbon steel with an O2 gas assist; a low quality cut to a depth of nearly 100 mm in carbon steel was also demonstrated. These data are compared with existing COIL and CO2 laser cutting data. COIL cuts carbon steel and stainless steel at approximately the same rate. For a given cut depth, power and spot size, COIL cuts steel approximately three times faster than a CO2 laser using an inert gas assist. COIL cutting speeds in carbon steel are improved by approximately a factor of three when an O2 assist is used in lieu of an N2 gas assist. With an N2 gas assist, COIL cuts aluminum at approximately the same rate as CO2 cuts steel. To improve the agreement between data and an existing theoretical cutting model, an empirical correction factor was added to the model; this modification provides excellent agreement with data.