Arc length behaviour and voltage predictions for GMAW-Sp aluminum procedures in the Lincoln Procedure Hand Book

Abstract

Heat input is a key component of a welding procedure, which is dependent on the several fall voltages composing a total voltage loss. As current practice is primarily reliant on trial and error to determine voltage settings for a desired heat input, a means to understand and predict the voltage loss is of interest to welding engineers. Voltage, amperage, and arc length measurements using ER4043 1.2 mm at varying voltages were used to break down fall voltage constituents for a given weld with GMAW-Sp. Arc length was defined as the distance from the weld pool to the point where the metal vapour and ionized gas boundary attach to the consumable, and measured over 5 droplet cycles to obtain a time average. Aluminum procedures in the Lincoln Procedure Hand Book (LPHB) with 1.2, 1.6, and 2.4 mm consumables were analyzed to predict the individual fall voltage constituents using experimental results. Expected arc lengths ranged from 13-26 mm depending on voltage prescribed in the procedure, and agreed with comparative experiments. Combined anode/cathode, and the arc column were major contributors to overall fall voltage with 64±3%, and 34±3%, respectively. Contact tip, electrode extension, and lead cables were minor contributors, each contributing less than 1.2% to the overall voltage loss.