Numerical Prediction on Dependence of the Arc Current and Swirl Gas Angle on Evaporation of Hafnium Cathode in a Plasma Cutting Arc

and Swirl Gas Angle on Evaporation of Hafnium Cathode in a Plasma Cutting Arc Nguyen Phi Long1, Y. Tanaka1, Y. Uesugi1, and Y. Yamaguchi2 1Division of Electrical Engineering and Computer Science, Kanazawa University, Kakuma, Kanazawa 920-1192, Japan 2Komatsu Industries Corporation, Japan Abstract: The effects of arc current and swirl gas angle on plasma cutting arc were investigated using a developed two-dimensional thermofluid model for arc plasma with considering hafnium (Hf) cathode evaporation. Numerical modeling is very important to predict the erosion amount of Hf cathode for different process parameters in the plasma cutting arcs. Results showed that larger swirl gas angle caused a high temperature plasma area in front of the cathode surface shrunken in radial direction and the flow patterns changed to opposite direction in front of the cathode at the swirl gas angle from 15 degrees to 30 degrees. This change in gas flow pattern makes Hf vapor transported along the center axis direction to the outlet of the nozzle. The total amount of mass loss of Hf cathode evaporation was predicted to be enhanced with increasing swirl gas angle and arc current.