TWI Industrial Member Report Summary 84/1979
By S A Westgate
This survey has been produced to review the present position on resistance welding of aluminium alloys in view of the increased interest in the use of aluminium alloy sheet in motor vehicles in recent years. The reason for this trend is an attempt to obtain improved fuel economy by reduction in vehicle weight. Emphasis is therefore placed particularly on commercial quality welding in mass production industry.
The various aspects of the resistance spot welding process reviewed are: material surface preparation, equipment, welding conditions, electrode life, mechanical properties of spot welds and quality control. Available information on the related processes, seam and projection welding, is also summarised. Recommended data is presented for resistance spot welding and seam welding using a. c. or d. c. equipment and levels of strength to be expected from spot welds are recorded.
One of the major factors which limits the widespread application of resistance spot welding to aluminium alloys is the short electrode life normally obtained. In recent years a good deal of effort has been devoted to extending electrode life to several thousand welds. The main areas of investigation have been surface preparation, electrode materials and electrode tip profile. Although electrode lives in excess of 2000 welds have been consistently achieved by a number of workers, this has yet to be achieved in production.