The aerodynamic interactions of the assist gas during fusion laser cutting are an essential parameter determining cutting performance. This subject has been object of multiple studies to determine the influence of the assist gas jet interactions with the workpiece in order to design assist gas injection systems which surpass the drawbacks exhibited by conventional cutting heads. Cutting heads incorporating off-axis de Laval nozzles to inject a supersonic gas jet has been demonstrated, by different authors, to be an effective option to increase performance and cut quality during fusion laser cutting of difficult materials. However, all efforts performed in this direction, have been accomplished using nozzles with axial symmetry.
In this work, the fundamentals of a novel cutting head incorporating an off-axis nozzle, with non-axial internal symmetry are described. Gas flow inside the cut kerf is analyzed by means of flow visualization techniques. Moreover, cutting results are compared to those obtained through cutting heads assisted by axial-symmetric de Laval nozzles and sonic nozzles in a configuration off-axis and coaxial respectively with the laser beam.