Study on the influence of geometry on welding forces
By Amarilys Ben Attar (Institut de Soudure), S. Zimmer-chevret (Arts et Métiers ParisTech), N. Jemal (ENIS), L. Langlois (ENIS)

Robotic Friction Stir Welding (RFSW) is an innovative process which permits to join aluminum materials with robots. Using robots to realize a FSW operation presents the drawback that the robots undergo elastic deformation during the welding due to the high forces induced by the process. This leads to the end effector deviation in position and orientation. The robot deflection is due to forces acting on the tool as welding. The forces are related to the tool geometry, the processing parameters and the welded material. A big study has be realized to investigate the relationship between tool geometry and forces applied as welding in steady state conditions. The starting point of the study was to modify the tool geometry used in the Robotic Friction Stir Welding application: a convex shoulder tool with a truncated cone pin with 3 flats and threads. All the geometry modifications were mainly performed on the pin. Example of tool geometry modification: with and without threads, with and without flats, flat bottom pin, etc. For each tool a process window was searched and the welds were analyzed to identify the internal quality of the weld. For each tool, the forces according to processing parameters were analyzed. The study will present with type of geometry leads to a reduction of welding forces (Fx, Fy) as Friction Stir Welding. The conclusion will help to better design FSW tools as welding with FSW robot.