Applications manager Peter Jowett says: “Our new subcontract welding division has proved a considerable success, attracting projects from a number of sectors. With that in mind, we decided the time was right to extend our offering to include research into welding techniques – particularly when involving small-scale components or the jointing of exotic and particularly difficult to weld alloys."
Patented by TWI (The Welding Institute), the FSW process combines frictional heat with precisely controlled forging pressure to produce extremely high-strength joints that are virtually defect free. It transforms the parent metal from a solid to a plasticised state. This occurs during a process that involves mechanically stirring the materials together to form a high-integrity, full-penetration welded joint. Used primarily for jointing aluminium, magnesium, copper, titanium, steel, lead and zinc, the Powerstir FSW process provides a clean, highly aesthetic alternative to traditional welding. Benefits include delivering proven weld quality, excellent mechanical properties, virtually no porosity and the opportunity for reduced wall thickness in many applications, according to PTG.
As part of its FSW research activities, PTG Heavy Industries has successfully welded aerospace-grade steel alloy and aerospace-grade titanium in thicknesses of 3 mm and 8 mm, using its fixed-pin tooling techniques. PTG Heavy Industries has also achieved excellent results when working with various exotic aluminium alloys, ranging from 2 mm to 35 mm in thickness, in a number of configurations.
Adds Jowett: “As a result of our successes, we especially look forward to applying our findings, approach and technologies to robust testing on other bespoke alloys that are used across the avionics sector. Our new research capability provides considerable opportunities for design engineers looking to balance weight and structural rigidity in order to achieve performance, capability and efficiency in fuselage and component design.”
Research bodies that have invested in Powerstir FSW laboratory machines from PTG Heavy Industries include the globally renowned ISF Welding and Joining Institute at RWTH Aachen University in North Rhine-Westphalia, and The University of Manchester’s Institute of Science and Technology (UMIST).
RWTH Aachen University’s research programme includes investigating the potential to accelerate the speed of the FSW process. RWTH Aachen selected the PTG machine for its uncompromising build quality and stability, as well as for its ability to provide real-time data logging – vital feedback of precise performance data, such as production monitoring, force control, weld temperature monitoring and joint tracking. UMIST was one of the very first academic institutions to acquire a Powerstir laboratory machine.
“Research departments from across the global aerospace and transport sectors have made Powerstir machines central to their studies into creating stronger, lighter and more aesthetically pleasing welds,” he says. “It is also worth noting that here in the UK, The Welding Institute uses a Powerstir machine for its ongoing work into FSW processes, joint strength and tool development.”
In recent years, Powerstir models have found favour also with companies from across the avionics and high-speed rail sectors. In a joint venture with its technology partners, for example, PTG Heavy Industries developed a Powerstir model for use in the manufacture of railway car bodies similar to those used with China’s record-breaking ‘Harmony’ high-speed train. This required the design and build of a Powerstir machine with a 30 m by 4 m gantry – a machine that is able to produce the longest single FSW railway panel welds in China at over 15 metres in length.
PTG’s smaller Powerstir laboratory models are typically used for educational and research purposes or for the manufacture of small components. They are particularly suited to welding thin wall sections, such as hydraulic cylinders, suspension dampers and heat exchanger components.
