Effect of tilt angle in FSW of polycarbonate sheets in butt configuration

The influence of the tilt angle on the quality of Friction Stir welds made on polycarbonate sheets is investigated, experimentally. Welding tests were conducted by varying the tilt angle and the welding speed to determine possible interactions between these process parameters. Temperature distribution, material flow, and processing loads were analyzed. The quality of the welds was assessed by means of mechanical characterization and morphological analysis. The results indicated that the processing loads and temperature increased when higher tilt angles were adopted. Under low welding speed (20 mm/s), this enabled to improve the mechanical behavior of the welds. On the other hand, high tilting involved different issues. The tensile strength of the welds was severely compromised as high tilting produced severe thinning of the weld seam. In addition, tilt angles higher than 2° involved great amount of material ejection. This material formed a coherent side flash, which required subsequent machining, and worsened the surface appearance of the welds.