“A demonstrable capability in joining aluminium alloy using friction stir welding” was all that was required by one of the world’s leading aerospace manufacturers when it contacted TWI recently.
It would indeed have been a tall order if TWI hadn’t invented the process in the nineties, or held two decades of experience in welding aluminium alloys. Instead the company rose to the challenge of assembling a demonstrator to the exact specifications demanded by the client concerned.
The finished work was to include six pieces of 4mm thickness aluminium which were to be joined using partial penetration friction stir welds to form a profiled panel. All welds were 600mm in length. So a programme of work was devised to satisfy the client’s needs.
The task in hand…
The friction stir welded profile was to form part of a larger technology demonstrator. Dimensional accuracy was therefore critical. The original design proposed by the client was not entirely suitable for friction stir welding. So TWI worked with the client to simplify manufacture through the adoption of more appropriate weld locations and also recommended the use of pre-rolled parts to ensure consistent curvature.
Quite simply TWI had to identify and demonstrate the process parameters and FSW tool designs to produce high quality partial penetration butt welds in 4mm thickness AA6082-T6 plate. It then had to apply these parameters to the manufacture of a profiled demonstrator panel for the client.
Appropriate material clamping is vital to the production of high quality friction stir welds. A cost-efficient versatile fixture was designed and manufactured to provide for all five friction stir welds in the demonstration part.
Welding trials were conducted on TWI’s ESAB SuperStir machine to determine the joining parameters required to produce the profiled panels.
A total of three profiled panels were produced and delivered to the client.
Conclusions and benefits
As a direct result of this work it was possible to produce three deliverables:
- FSW tool designs were developed for 2mm deep partial penetration butt welds in AA6082 aluminium alloy.
- FSW process parameters were identified that produce high quality welds.
- Profiled demonstration panels were successfully produced and delivered to the client.
