In this project, the aim was to test the working range of the friction stir welding installation located in the company in relation to the maximum weldable plate thickness on the AW‑6082 aluminium material. The reason for this was the assignment from a university to manufacture a friction-stir-welded joint on 30 mm thick aluminium plates (AW‑6082) with a weld penetration depth of 25 mm.
According to the specifications of the manufacturer (ESAB), the working range of the friction stir welding installation was limited to a plate thickness of max. 10 mm with aluminium. In order to achieve the desired weld penetration depth of 25 mm, particular care was needed when configuring the tool. In this respect, it was not so much the axial and feed forces to be applied which proved to be problematical but rather the torque of the working spindle. Therefore, the diameter of the tool shoulder was kept as small as possible. This also placed extreme limits on the diameter of the pin.
This resulted in a tool whose pin had a diameter of just 15 mm at the shoulder with a length of 25 mm. It was important to input the required heat as uniformly as possible over the entire weld depth and to ensure effective material transport. A few changes to the contour and profiling of the tool were needed for this purpose. At the end of the process, there was a tool with which the demanded weld penetration depth could be achieved successfully on the specimen plates. It should be borne in mind that it was not possible to achieve the strength values of the base material because of the substantially reduced welding speed.
Furthermore, our specimen plates were comparatively small (approx. 250 mm x 500 mm). This limited the heat dissipation somewhat and benefitted the required forces and moments.