Friction stir weld process evaluation by multi-axial transducer

Friction stir welding (FSW) is a solid state joining technique that is rapidly establishing itself as an approved production technique and it remains the focus of significant international research effort. Scientific understanding of the FSW process is necessary for its successful automation. The interaction between the rotating tool and the alloy is complex, making the determination of the contribution of various process parameters (tool geometry, temperature, rake angle, speed and feed) to the desired weld properties difficult. The construction of a rotating multi-axial transducer has been realised. This allows online and offline measurement of process responses (force footprint, energy, temperature, etc.) and can be incorporated into a feedback control system for the processes technical and economic trade-off regulation. This paper describes the design, development and calibration of this multi-axial transducer. The application of the real-time process data to develop the force footprint as an aid for gaining scientific insight into FSW is also discussed.