The heat input is a key component of a welding procedure, which is dependent on the several fall voltages that compose the total voltage fall. As current practice is primarily reliant on trial and error to determine voltage settings for a desired heat input, having a means to predict the voltage fall is of interest to welding engineers. To predict heat input, the fall voltages that make up the total voltage fall in arc welding must be understood. To gain an understanding of voltage fall predictions, welding voltages were calculated in this study by considering fall voltage contributions in the arc and compared to over 150 welding procedures with different parameters, transfer modes and base metals (carbon steel, stainless steel, aluminum, and copper). The concept of self-regulating arc in GMAW was used to define arc length in relation to wire diameter. An arc length equation was derived for GMAW-Sp and a definition of half the wire diameter was considered for GMAW-S. Cathode and anode fall voltages proved to contribute ~80% of the total voltage fall with noticeably less for aluminum (~65%). Arc column and electrode extension fall voltage contributions were found to correlate to the resistivity of consumable material.

Moderated by: Mark Schneider / Jakob Olofsson