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Friction Stir Welding (FSW) Moving into the Medical Sector

LTi Metaltech, based in Abingdon, specialises in the precision fabrication and welding of high performance vessels and structures and are recognised as experts in high integrity welded structures capable of withstanding extreme pressure, vacuum and temperature differentials, delivering cutting edge technologies for industries including Fusion and Nuclear, Healthcare and Renewables, with further capabilities and insights targeted at Transport and Rail. In order to maintain technological competitiveness and also its portfolio of welding solutions and welded product offerings, LTi started to collaborate with TWI on the Friction Stir Welding (FSW) process, with the aim of taking FSW in-house for production.

The initial interest came from the desire to move away from autogenous DC arc welding, that has been used for almost 20 years at LTi, to weld components made using AA1xxx, AA3xxx and AA5xxx series aluminium alloys for a specific medical application. In order to improve production and quality in welding solutions and welded products offerings, LTI have identified the need for investment in equipment and considered other fabrication processes as part of this process, with FSW being the leading alternative. This resulted in LTi commissioning TWI to undertake two FSW procedure development studies.

The two projects included FSW procedure development studies, carried out at TWI UK, on AA1xxx and AA5xxx series aluminium alloys. In these studies TWI FSW worked on identifying the FSW tool designs, FSW welding parameters and weld quality. The studies were carried out in line with the ISO 25239:2011 Part 1 to 5: FSW of Aluminium. Aside from the practical laboratory tasks in the development studies, TWI also worked with LTi, and represented LTi, in liaising with their selected CNC machine manufacturers to identify machines suitable for FSW. The information gained through the practical laboratory tasks aided the identification of the FSW machine specifications required for LTi’s FSW application.

Based on the two completed projects, LTi have indicated that TWI’s support will be further required, once the purchasing process of FSW machine has started, to support LTi in machine testing and commissioning tasks. TWI will use the welding procedures, developed in the two completed projects, as the baseline during the testing and commissioning the FSW machine, TWI have in the past assessed machine capabilities with on-site factory acceptance tests in different parts of the world on behalf of TWI Industrial Members, and tested the welds produced to match the standards required by TWI Industrial Members.

With LTi’s motivation in taking FSW to in-house production, it will now open up new business opportunities for FSW production/fabrication in the UK. By assisting LTi in FSW implementation, TWI will be able to ensure the Industrial Member will remain competitive by efficiently producing reliable products, and continue the growth of its business.

TWI would like to acknowledge LTi for funding the two projects, including the feedback provided, and look forward to more future collaboration. The two projects gained ‘Triple E’ ratings in TWI’s Client Satisfaction Survey, for excellence in three categories - Technical Quality, Delivery Timescale and TWI Staff Support, from the LTi:

Feedback from Project 1: This was the first time looking at FSW, the technical knowledge and support was excellent with constant updates throughout the project.

Feedback from Project 2: Very professional from first contact, great communication throughout the project and will look forward to their continued support.

Form more information, please email

Avatar Dr Steve Dodds Nuclear Power Sector Manager

Steve joined TWI in the Friction and Forge Processes (FFP) team in 2013 following his PhD, which focussed on developing the friction stir welding of steel. As a Senior Project Leader and later as Section Manager, Steve delivered a broad range of projects, ranging from pre-competitive research through to manufacturing support and technology transfer. Steve has a particular interest in the friction welding of dissimilar metals/materials and redesigning components to access the benefits of friction joining.

In 2021 Steve became the Nuclear Power Sector Manager at TWI, responsible for all aspects of Nuclear and Big Science interactions with TWI Members and the wider global community.