Weld quality analysis and evaluation of plasma arc welds in electrical stators

The use of plasma arc welding (PAW) has increased in the last years as a substitute for the gas tungsten arc welding in the automotive, electrical and appliance industries. Although the use of PAW in the industry has increased, there are still a limited number of theoretical methods and simulation tools to predict the metal flow characteristics and its interaction with the process parameters during the welding process. Therefore, weld design must still rely on the designer’s experience and the trial-and-error method. As a consequence, the process parameters and the weld quality may not be as originally expected at the design process. In this paper, a weld quality analysis of the PAW process is presented to guarantee a good quality of the product. To measure the influence of process parameters on weld quality, first, “quality” is defined. Weld quality measurement methods are then proposed based on visual inspection, electrical tests and mechanical tests of the welds. Using these methods and the experimental data obtained from the actual welding process at the production line, a new approach to evaluate the weld quality is proposed based on a circular shape model of the weld cross-section area. Finally, a relationship between the weld geometry and weld quality is proposed and intended to be used as a practical online monitoring method of weld quality.