Friction Stir Spot Welding

Process definition:

Friction Stir Spot Welding (FSpW) is a solid-state welding process for overlapping sheet metals in which a three-part tool, consisting of a rotating pin and sleeve and a non-rotating downholder, penetrates the sheets and stirs the material in such a way that a solid bond between them is formed. By refilling the material back into the joint zone, a smooth surface of the sheet compound can be restored.  


  • overlap sheet joints with upper sheet sizes 0,5 mm … 3 mm

  • material combinations Al/Al, Mg/Al, Al/Fe, Mg/Fe, etc.

  • suitable for automotive, aeronautic, astronautic and railway applications


  • very good strength (fatigue, peeling, tensile shear, etc.)

  • high reproducibility of process

  • short welding cycles

  • different sheet metal thicknesses can be welded by the same tool with adapted welding programs

  • all advantages of friction welding also hold for FSpW


Above typical process runs are displayed. With the aid of the process simulation the tool design and process parameters can be discussed in advance of experimental study. The simulation is able to calculate:

  • the inner tool forces

  • the “refill” behavior

  • the stir profile of the joint

  • frictional heat generation

  • temperature, pressure, stress and deformation profiles of arbitrary locations within the sheets and tools