Selecting parameters for GMAW using dimensional analysis

A method for analyzing gas metal arc welding procedures was developed to select welding parameters that lead to a desired operating condition. Analytical relationships between welding parameters and process variables were established by regression and dimensional analysis of experimental data. This data was obtained from a detailed GMA welding experiment in which the welding parameters were precisely controlled and the process variables precisely measured and correlated. Using nondimensional variables to correlate experimental data, accurate analytical relationships between welding parameters, arc process variables, and bead geometry were obtained. The analytical relationships for bead geometry extended the work of previous researchers by introducing a nondimensional mass transfer number and demonstrating the dependence of bead geometry on mass transfer as well as heat transfer. These relationships were used to identify a range of stable welding parameters and to find the welding parameters needed to ensure process constraints were met. Specific welding parameters were found by controlling arc length and weld bead geometry to ensure arc stability, adequate weld bead size, and adequate joint penetration.