TWI

A review is presented of process development work undertaken with regard to a machine concept assessment and the realisation of a fully 3D-capable 5-axis parallel kinematic friction stir welding machine, a so-called pentapod, suitable for large and complex 3D structures up to 7 m in length. Typical process control aspects are described, such as the capability to control force, torque and relative tool position as well as a facility to integrate the control value as an additional virtual axis into the CNC program. The relationship between control loop development and tolerance management is examined and some examples of tolerance studies on friction stir welded 6082-T6 aluminium alloy butt joints are reported. Applications to the welding of aircraft structures (e.g. tailored welded blanks) and mixed material joints are discussed and results from research projects are presented.

10th International Symposium, 20-22 May 2014, Session 8A: Robotic and Non Linear, Paper 01