Assessing the effects of solid wire electrode extension (stick out) increase in MIG/MAG welding

Abstract

In conventional MIG/MAG welding process, the root of some of the most frequent problems is related to current variation due to solid wire electrode extension (stick out) alteration. This becomes most relevant in semi-automatic welding procedures, where the welding operator is responsible for holding the torch. Inevitably, the contact tip-to-workpiece distance, and as a result, the stick out length, will oscillate due to operational difficulties, such as complex geometry and out-of-position welding. Since the average current has decisive influence over various weld properties, variations in its values incur in reduction of process and weld regularity, repeatability, robustness and reliability. The present work investigates and quantifies the effects such as current drop and electrode temperature profile based on well-known theoretical-analytical concepts under an application oriented standpoint, so as to scientifically support research and development of modern MIG/MAG welding adaptive systems. Results pointed a higher wire preheating degree in spite of lower current levels when stick out is increased. Experiments showed a weld bead geometrical reduction, which can be avoided through an intelligent system, capable of identifying welding current behavior, electrode voltage fall and electrical resistance curves for process online correction and prevention of possible defects.

Sensitivity analysis and multi-objective optimization of tungsten inert gas (TIG) welding based on numerical simulation

“…A high feeding rate requires a high current. If this is associated with low welding speed, it can result in lower penetration [41][42][43].…”

Effect of the Electrode Extension on the Geometry of Parts Made of 316LSi Steel by Wire Arc Additive Manufacturing Method (WAAM)

“…When welding stainless steel, lower extension values are more commonly used due to its higher resistance. Conversely, a longer extension is used when using a spray arc and larger electrode diameters [17][18][19]. Using an excessively long arc in active gases can reduce the mechanical properties of the weld.…”