Image analysis of electrode degradation in resistance spot welding of aluminium

A study was carried out of the characteristics of electrode degradation in resistance spot welding of aluminium, and its influence on weld quality. Based on analysis of electrode life test results, an imaging approach was developed to determine quantitatively the status of electrode degradation, in which three parameters were defined to represent the tip surface characteristics, namely, relative radius, edge concentration, and eccentricity. This image analysis revealed a clear relationship between these defined electrode surface features and the weld quality, based on which a reasonable understanding was achieved of the causes of weld quality deterioration in electrode life tests.