TWI Industrial Member Report Summary 991/2011
By K A Beamish and M J Russell
Process management for friction stir welding (FSW) is a developing area. A range of monitoring and process management approaches are currently applied by industrial users, as described in the first report from this project (Blignault, 2008). An entry-level system is capable of monitoring the core process variables of tool rotation speed, tool position (in x, y, and z), and welding speed. Force measurement has been of interest for some time and maintenance of a set z-force provides one of the principal methods of process control, the other (dominant) method being control of z-axis position. Machine manufacturers are now integrating enhanced process monitoring systems into their equipment. Advanced monitoring and control of FSW has resulted in the emergence of in-process monitoring as a potential quality control method.
This Core Research Programme (CRP) project is focused on the measurement and interpretation of multiple process parameters such as tool forces, temperature and torque by means of a precision in-situ monitoring system. The data generated is compared with that obtained from basic and enhanced process monitoring systems. Force, torque and temperature traces can be used to establish a reference against which subsequent welds can be compared. Characteristic FSW flaws were intentionally generated to demonstrate the identification of potential quality issues. In future such data may be used as part of Quality Control procedures and could ultimately be incorporated into machine control systems. An assessment of two representative tool designs, the MX-TrifluteTM and the MX-TriflatTM has been made over a range of welding conditions. The in-situ monitoring system has been used to identify the characteristic force footprints of the individual design elements of these tools which gives a quantitative basis for future tool development.
- Investigate the action of representative FSW tool designs and to assess the influence of individual design features.
- Investigate and demonstrate the potential for applying an integrated FSW process monitoring system as an on-line Quality Assurance tool.