Investigation of the gas flow in laser beam cutting

The cutting gas jet is an essential parameter for laser beam cutting. The choice of the gas type defines the working atmosphere at the cutting front. When using oxygen additional energy is added to the cutting process by exothermal reaction, while the use of non-ractive gases during laser beam fusion cutting acoids additional reaction with the workpiece. The molten or vaporized material is blown out of the cutting kerf by the gas jet. It affects the melt film by shearing and pressure forces. Both momentum components are influenced by the velocity and pressure distribution of the gas flow within the cutting kerf. With the help of the Schlieren method these gasdynamical influences can be investigated. As a result, the principal pattern of the cutting gas flow and its functional dependences from nozzle design and nozzle adjustment, cutting gas pressure and cutting kerf geometry are reported in this paper.