TWI Industrial Member Report Summary 58/1978
By G R Salter, K R Spiller and J Doherty
A comparison has been made of the direct costs involved when making gas-shielded arc welds in 3.2mm to 25.4mm thick aluminium-magnesium alloy using a range of processes.
The results indicate that the most expensive process is generally argon-shielded AC TIG-welding because of the low welding speed and high consumable costs involved. Helium-shielded DC is potentially a more economic TIG process. The most economic process for 3.2mm sheet is argon MIG-welding with 0.8mm diameter wire. Pulsed MIG-welding is significantly more expensive. The significant effect of back chipping as a major labour cost was also noted.
No clear economic difference could be found between the use of argon, 70%helium-30%argon, and helium for MIG butt and fillet welds of 6mm or larger. The increased cost and flow rates of helium and helium-argon were offset by the higher joining rates and reduced quantities of wire used.
The most important factor affecting this analysis is the comparative cost of helium and argon. The comparison would require reassessment if the cost ratio of 2:1 for helium:argon was changed significantly.