Techniques for the improvement of carbon steels welds: under the SISF and DIDF welding schemes using pneumatic- and servo-based electrode actuating systems in resistance spot welding

In this experimental study, the carbon steel welds are investigated for distinctive changes between the pneumatic- and servo-based electrode actuation. Also, two welding conditions, and the name of schemes, are introduced, as to distinguish the weld formation with respect to its common process variants. A C-typed body frame of spot welding machine (75 kVA) is employed to undertake the entire experiments. Initially, the pneumatic-based electrode actuating system is used to weld the carbon steels under single current and single force (SISF) welding scheme and later, the electrode actuation system was transformed into a servo-based system. With the servo-based system, the SISF and dual current and dual force (DIDF) welding schemes are both carried out to distinguish the welds formation. Eventually, the welded samples underwent the tensile test, hardness test, post-crack pattern recognition, and metallurgical study. Results have shown that the DIDF welding scheme is much better than the SISF welding scheme because the servo-based system performs well than the pneumatic-based system in producing force consistencies. In other words, the force profiles influence the fusion process directly which affects the heat generation as well as the heat diffusion.