An investigation on co-axial water-jet assisted fiber laser cutting of metal sheets

Abstract

Water assisted laser cutting has received significant attention in recent times with assurance of many advantages than conventional gas assisted laser cutting. A comparative study between co-axial water-jet and gas-jet assisted laser cutting of thin sheets of mild steel (MS) and titanium (Ti) by fiber laser is presented. Fiber laser (1.07µm wavelength) was utilised because of its low absorption in water. The cut quality was evaluated in terms of average kerf, projected dross height, heat affected zone (HAZ) and cut surface roughness. It was observed that a broad range process parameter could produce consistent cut quality in MS. However, oxygen assisted cutting could produce better quality only with optimised parameters at high laser power and high cutting speed. In Ti cutting the water-jet assisted laser cutting performed better over the entire range of process parameters compared with gas assisted cutting. The specific energy, defined as the amount of laser energy required to remove unit volume of material was found more in case of water-jet assisted laser cutting process. It is mainly due to various losses associated with water assisted laser processing such as absorption of laser energy in water and scattering at the interaction zone.