FSSW is a new spot welding technique to join overlapping workpieces and
intends to replace existing techniques like resistance spot welding. The
concept was first developed at Mazda Motor Corporation and Kawasaki
Heavy Industry as an extension of FSW for joining Al alloys (Sakano
et al. 2001). The method consists of only (a) the plunge and dwell and
(c) retract stages of FSW (see Fig. 2.1). Due to absence of stage (b) of FSW
(traverse stage) in FSSW, there is no concept of advancing side and retreating
side, and the process is considered to be symmetrical.