The influence of small variations of wire characteristics on gas metal arc welding process stability

Abstract

Abstract Gas metal arc welding (GMAW) is highly sensitive to small changes in operational variables. This sensitivity can make it difficult to optimize operational conditions and to diagnose process faults. This paper evaluates the influence of small differences in wire characteristics on GMAW-CO2 operational conditions. A total of 16 samples of AWS type ER70S-6 wire were produced from the same steel batch with small and controled differences in diameter, mechanical strength, cast and helix. For each sample, bead-on-plate welding trials were carried out using the same wire feeding rate (6 m min−1) over a voltage range of 13–27 V. Welding current and voltage were recorded by a microcomputer using an A/D system. Spatter produced during each welding trial was collected, weighed and compared with the weight of the weld bead. Data were evaluated using factorial analysis and graphical techniques to assess the effect of different wire characteristics on the welding process. Results showed that differences in wire diameter produced the most important changes in process characteristics. These changes were related to differences in fusion rate and caused a small drift in optimal operational conditions. The other characteristics analyzed produced only minor changes in process characteristics.