Numerical and experimental study on influence of tool plunging force and shoulder size on thermal history of friction stir welding

Friction stir welding (FSW) process is a solid stated joining process. Important process parameters include the tool rpm, travel speed, tool dimensions and the downward force on the tool. Heating is caused by rubbing of the tool faces against the workpiece and by visco–plastic dissipation of mechanical energy. There is a unique combination of shear and normal forces in FSW. In this present study gaps of FSW were determined and two very much important process parameters effect on FSW (i.e., tool plunging force and shoulder size) was presented. This study investigates the effect of tool plunging force and tool shoulder size on heat generation of FSW by using 3–D finite element (FE) transient thermal analysis. It was noticed that both plunging force and shoulder diameter have considerable effect on FSW process. Suitable correlations have been made between shoulder diameter vs. peak temperature and tool plunging force vs. peak temperature. Also generalised optimum parameters were established by considering the above said parameters. The present developed FE model results were well matched with experimental results. [Received 29 September 2013; Revised 31 July 2014; Accepted 3 October 2014]