The process / properties
High precision joining by means of targeted movement
The workpieces to be joined are clamped between an anvil and a clamping ring. The punch contains a rotating pin and sleeve that create frictional heat on the surface of the workpiece, thus plasticizing the local area of the material.
The pin and sleeve are axially shifted relative to one another. During this process, the sleeve penetrates into the workpiece and the pin withdraws to leave room for the displaced material.
This motion is continued until the sleeve penetrates into the bottom workpiece. The process is then reversed. The sleeve is pulled back and the pin pushes the material into the space left by the sleeve’s withdrawal.
The spot weld is completed when pin and sleeve have returned to their original positions and a smooth sheet surface has been created. The clamping force is maintained until the joining process is completely finished.
What can be joined:
- Friction spot welding makes it possible to create point-shaped lap joints. At present, depending on the tool used, spot diameters of between 5 and 11 mm in sheet thicknesses ranging from 0.2 to 8 mm can be realised.
- Multiple-sheet joints are also possible without further ado.
- As it is also possible to introduce additional material into the joint, friction spot welding can also be used for the repair of surface pores or for filling the final hole resulting from friction stir welding.
- So far friction spot welding has been optimised for joining the light metal aluminium, although multi-material joints are also possible. A range of materials similar to that for friction stir welding is presumed.
The quality you can expect:
- Friction spot welded joints are materially bonded and free of faults.
- They impress with extreme strength, and that without the use of any additional materials or joining elements.
- Large weld spot diameters are also possible even for thin sheet thicknesses The reverse side of the sheet remains largely unaffected by the process.
Selected examples from our everyday practice
Lap Joint EN AW-6181 T4
Material thickness 1.7 on 1.7 mm
Welding duration 2.2s
Shear Strength | ˜7 kN |
Cross Tension Strength | ˜3 kN |
Lap Joint EN AW-5042
Material thickness 1.5 on 1.5 mm
Welding duration 2.0s
Shear Strength | ˜6.5 kN |
Cross Tension Strength | ˜2.8 kN |
Lap Joint EN AW-7075
Material thickness 5 on 5 mm
Shear Strength | >20 kN |