Investigation into Development of Liquid Layer and Formation of Surface Plasma During CO2 Laser Cutting Process

Abstract

Interaction studies between the liquid metal and gas jet during laser cutting were made and relationships between the various parameters influencing the cutting action were identified theoretically. In the theoretical analysis, the effect of the jet on the process, due to jet momentum and the interface (gas-liquid) shear stress, were considered. On the experimental side, the work was carried out in two parts. In the first part, cutting of mild steel at the different thickness levels was carried out using an argon/oxygen gas mixture at 5/1 pressure ratio and 138 kPa total pressure. The depth of resolidification around the keyhole resulted from the cutting process and was examined microscopically. In the second part, the motion of plasma generated during the laser cutting process was monitored using a CCD (icharge coupled device) camera, fibre-optic probe and microlens camera. In this case oxygen was used as the assisting gas.