The contribution of shoulder friction heat in FSW is ~80%, which benefits the material to plasticize and weld formation.
In this paper, Different recessed tool shoulder features such as scrolls, ridges, concentric circles, knurling, grooves and spiral are considered, the equal volume of recess is maintained to design different features, Initially to understand the material flow a Copper strip (of 0.5 mm thick) is inserted with the configurations of parallel to weld line (Center, Advancing side(AS) Tangent to pin, Retreating side(RS) Tangent to pin) & perpendicular to weld line (AS, RS, both) which are performed with best tool pin and varied tool shoulders. The results reveal that because of shoulder and pin driven flows the copper strip is completely sheared off and formed a particle track in the weld zone. Shoulder features improved the heat generation. Joints with Knurling tool and Ridges tool shoulder features, resulted with better mechanical properties.