Experimental Analysis of FSW Process Forces

This paper presents the results of research work on linear friction stir welding (FSW) of magnesium AZ31 and aluminum 2024 alloys. During the FSW process, forces exerted by a tool on joined materials were measured. The measurements of forces were taken in three directions, vertical (Z axis) and horizontal (X and Y axes) directions, using high-sensitive piezoelectric dynamometer. The force analysis was done for three stages of welding process: plunging, dwelling, and welding. Conclusions regarding the force reaction of materials to be welded were formulated. It was found that the first two stages of the process, plunging and dwelling, are very important for the correct welding. In the plunging stage, a tool exerts the greatest forces and unit pressures (at the Z direction) on joined materials; during the dwelling stage, thermal conditions of the process are established. The welding stage was divided into two substages: the initial unstable and the subsequent long-term stabilized one.