A New Approach for Robust High-Productivity Resistance Spot Welding of Aluminium

Process consistency and long electrode-life are essential requirements for users of resistance spot welding (RSW) in the automotive industry. RSW is the dominant joining process for manufacturing automotive body structures from sheet materials. The technique is cost effective (particularly in high-volume production), makes joints rapidly, is easy to automate, and it has no per-joint consumables. These beneficial attributes apply equally to RSW of aluminium automotive structures. However, there has been some reluctance in the industry to embrace spot welding for aluminium. This is because the electrode-life is much shorter than that experienced when welding traditional uncoated plain-carbon steels, and there is a general lack of confidence in the consistency of the process. This paper describes a potentially non-intrusive method that addresses these concerns. By instituting a technique where the electrodes are lightly cleaned on a very regular basis, overall electrode-life is increased by at least a factor of three, and the consistency of the joining process is significantly improved. Weld failure rates are reduced below 1%, and the tensile performance of individual welds remains in a steady-state for thousands of welds. Furthermore, with the electrodes constantly maintained in good condition, online quality monitoring of the process becomes a practical proposition.