Using laser profilometry to monitor electrode wear during resistance spot welding

Abstract A new method for rapid and accurate acquisition of the shape of an electrode indentation in a workpiece during resistance spot welding (RSW) is presented. The method is based on illumination of the indentation with structured laser light and detection of the image of the illuminated object using a charge coupled device camera. The image from the camera is digitised using a frame grabber and fed into a personal computer where it is processed and analysed. This paper presents the basic principles of the method and discusses the image processing algorithms developed to measure the indentation shape characteristics, such as diameter, depth, and volume. Results from an application of the method to study electrode wear during RSW of zinc coated steel are also presented.