Energy balance study of gas-shielded arc welding processes

Within this manuscript, the energy balance for gas-shielded arc welding processes based on experimental investigations is discussed. The energy input into the joint is measured using a novel calorimetric system. Energy losses of the welding arc due to conduction, convection, and radiation are determined using a double-walled bell-shaped measurement system. Cooling losses of the welding equipment are recorded by a measurement unit integrated in the cooling system. The energy balance is determined for a set of different process and welding parameters. The influence of each parameter on the energy balance is systematically studied and illustrated. Measurements confirm that it is possible to increase the efficiency of welding processes, for example by reducing the wire feed speed, using helium gas, or increasing the distance of the welding torch to the metal plate. Contrarily, increasing the current or voltage, or reducing the shielding gas flow, reduces the process efficiency. The difference between the lowest and highest achievable value of efficiency can be more than 15 % for one specific welding process. Analysis revealed two main causes for energy losses: first, the radiation, convection, and conduction losses of the arc, and second, the cooling losses in the welding torch and the current-carrying ground cable. By summation of the three measured energy shares - heat input in the component; radiation, convection, and conduction losses of the arc; and the heat dissipation into the cooling system of the welding source - 95 % of the total energy flow can be described and visualized. This knowledge increases the understanding of the joining process and also allows drawing conclusions on energy-saving capabilities.