Techno-economic evaluation of reducing shielding gas consumption in GMAW whilst maintaining weld quality

A series of experimental trials have been conducted to investigate the effects of reducing the shielding gas consumption in gas metal arc welding (GMAW). A number of claims have been made as to potential shielding gas savings in the GMAW process when using gas-saving devices such as commercially available self-regulating valves. However, the literature and data available on weld quality obtained as a result of reducing the shielding gas flow rate is not readily available, so the thrust of this study is to present a new body of data to report on the technical and economic merits of controlling the shielding gas flow rate using (a) a conventional flow meter and (b) a ‘new to market’ self-regulating gas-saving device. It has been determined that, in a draft-free environment, the shielding gas flow rate can be reduced to 6 L/min without diminishing weld quality, although a lower flow rate was more susceptible to the effects of cross-drafts, and the weld quality level was compromised. In addition to the economic savings associated with reducing the shielding gas flow rate, there are several weld aspects that have been found to be influenced by the shielding gas flow rate including penetration, leg length, distortion and peak temperature, thus suggesting that the heat transfer efficiency is affected by the shielding gas flow rate. This significant finding supports the view that there is scope to increase the travel speed when implementing a lower flow rate and, consequently, enhance productivity.