Energy balance in disk and CO2 laser beam inert gas fusion cutting

Experimental, numerical and analytical investigations were performed to give a possible explanation of the differences in cutting quality detected for inert gas laser beam cutting process performed with disk and CO 2 laser sources. Cutting experiments were carried out at maximum cutting speed on cold work steel test specimens with different sheet thicknesses. The particular feature of the applied experimental setup was the similar geometry of both the CO 2 and the disk laser beam with comparable values of the focus diameter and the Rayleigh length. The thermodynamic analysis was based on experimentally primary losses evaluation by means of polymethylmethacrylate (PMMA) blocks, on numerical computation of conductive power losses and analytical calculation of the remaining terms of energy ba lance. Energy balance allowed the evaluation of secondary losses and proportion of vaporized kerf volume used for justifying the lower quality of disk laser cuts. The lower proportion of vaporized kerf volume detected for disk laser cuts results in an increased process temperature, thus an increase of viscosity of molten material and the subsequent more difficult ejection of the melted material from the cut kerf.