OXYGEN ASSISTED LASER CUTTING MECHANISM - A LAMINAR BOUNDARY-LAYER APPROACH INCLUDING THE COMBUSTION PROCESS

The present study examines the combined effects of chemical reactions taking place between a gas jet and molten metal, the cooling effect of the jet and the evaporation of metal, during a CO2 laser cutting proc ess. A laminar boundary layer approach was used to develop a theoretic al model for the oxygen gas jet laser cutting mechanism. An experiment was carried out to monitor the keyhole formation using a video record er and detect the light emitted from the entrance and exist surfaces o f the workpiece using a fibre-optic probe during the cutting process, The experimental study was extended to employ two different workpiece materials (stainless steel and mild steel) at two thicknesses, and var ying oxygen assisting gas pressures. It is found that the theoretical model developed in the present study is valid for a cutting speed of a bout 30 mm s(-1) and all jet velocities up to sonic, since the effect of shock is excluded in the model.