TWI Industrial Member Report Summary 696/2000
R Johnson and N L Horrex
Friction stir welding (FSW) was developed at TWI and resulted in a patent application in December 1991. The process operates by a rotating tool being plunged into softer material and then traversed through it. The material is plasticised by the friction heat generated by the tool as it rotates and, without any melting, the material is swept around the tool from the front to the back in order to effect a weld. TWI has been performing an increasing amount of work for industrial members as well as developing a further understanding of the technology through the Core Research Programme. A need has been identified to quantify the FSW forces and torque developed by the process in order to transfer the technology to industrial equipment, including robots and machines operating under closed loop control.
The forces that are generated during FSW are often assessed by indirect methods, for example based on deflections measured by strain gauges attached to the welding machine, or by force tables. There are now available, however, more direct instruments such as dynamometers that can be used either in conjunction with or without force tables, and a new assessment of the FSW forces developed during processing has recently been started at TWI. The results will be of interest to FSW machine designers and to those wanting to specify FSW tools to be manipulated by industrial robots.
- To evaluate a commercially available dynamometer for the measurement of the horizontal and vertical forces and the torque generated during FSW operations.
- To compare the forces and torques generated during the friction stir welding of different aluminium alloys.