Mandrel Tool Probe For Friction Stir Welding

A tool for performing a friction-stir process, the tool comprising:

• a support body having a shoulder at its distal end;
• and
• a probe extending outwardly from the shoulder, the support body, shoulder and probe being concentric and rotatable about a given axis,
• wherein the probe includes a set of a plurality of physically-separate, spiraled surfaces each of which has a linear or curved cross-section that extends along a length of the probe at a constant or varying spiral angle around the circumference of the probe, and wherein the probe has a cross-section with a constant shape along the length of the probe, the cross-section of the probe including a plurality of major segments each of which is formed of the cross-section of a respective spiraled surface.