Online quality control of Resistance Spot Welding for automotive production

The aim of this thesis is to provide an integrated real-time control system for resistance spot welding (RSW) in FCA plants, where I began my internship in March. This project is suggested by a colleague of Manufacturing quality who purposed to eliminate statistical ultrasonic and hammer/chisel control, which are both too expensive for the production, due to the fact that they require expert and trained workers. Statistical control is mainly used to evaluate RSW process deviation and to eventually set up the machine in order to correct it. However, this system is not always able to find out all the incorrect points of the vehicles, causing excessive noise and vibration problems during the vehicle test. Therefore, the “online control system” must solve the problem of non- conformity points by increasing the robustness of the process, thanks to the automatic evaluation of the spot-weld by the welding system. In fact, this technology includes spot gun and control system, using the Joule effect to fuse the sheet metal layer and join the parts. This project considers the output parameter of the welding process, in order to find a correlation with statistical control results, which could help to create automatic reports of the spot by the welding tool. The abovementioned analysis has been developed and tested in FCA Melfi plant on a “Jeep Renegade” model by applying the proposed control process for the development of the body-in-white shop.