Manufacturing a Single Ultrasonic Tool Set of Vibrational friction stir welding in Bending and Axial Modes

Friction stir welding has been categorized amongst permanent joining methods. Since its thermomechanical nature, solid-state joining and high welding loads, Friction stir welding process needs sturdy tools, fixture, and machine tool. Combination of this process along with ultrasonic vibrations decreases welding loads and improves the weld quality. In this study, the idea of comparing superimposed axial and bending ultrasonic vibrational modes on friction stir welding process led to producing a unique set of friction stir welding tool along with an ultrasonic transducer. In fact, one of the aims of this study concerns designing a single ultrasonic assisted friction stir welding tool set which will be able to vibrate in both axial and bending modes separately in different frequencies. In addition, the impressive effects of mass and inertia variations on the weld, due to the usage of the distinct tool set for each modal frequency, will be removed. The final modal analyzed model was manufactured and the amplitude of vibrations in both mentioned modes was measured experimentally. Results indicated that the use of bending vibrations leads to the formation of joints with much more quality than implementing the axial vibrations. Furthermore, doubled amplitudes from 8 μm to 16 μm in bending mode, unlike axial mode, improved the weld ultimate tensile strength.