Theoretical and experimental analysis of a hybrid industrial robot used for friction stir welding

Friction stir welding (FSW) is a joining technique of industrial relevance for the high quality of the welds even in case the metal sheets are made by different materials. Numeric control machines are often used in FSW because they provide the stiness and thrust ability needed in the process, but they usually have a reduced versatility if compared with robotic cells. A regulation of the interaction loads between the welding tool and the weld pieces is often required in order to carry out high quality welds. This paper highlights the main aspects involved in the process of FSW realized by means of a robotic manufacturing cell, showing the outcomes of theoretical and experimental analyses. The cell is equipped with a hybrid industrial robot, whose static performance is successfully exploited for the realization of welding products with high mechanical properties. The robot exibility of use is addressed. Several tests allow to gain a deeper understanding of the effect of technological parameters on FSW processes. Such information can be used for the development of modelbased controllers, which are assumed to eectively improve accuracy and process stability also in the welding of complex geometries.