TWI Industrial Member STL develops new bonding technique
Thermal processing, involving the application of thermal energy to transform materials such as metal and ceramics into industrial parts and components, is widely used in manufacturing processes across various sectors. Therefore, reflecting its importance to industry, TWI has a dedicated Thermal Processing Technologies (TPT) Section whose aim is to support TWI Industrial Member companies who use thermal processing, to stay at the forefront of this area. In addition, TWI has a suite of specialist furnaces in its engineering laboratories which can be used for TPT related project work.
Samuel Taylor Limited (STL) has been providing innovative, precision engineering products to markets throughout the world for over 100 years, pioneering the first electrically-driven rolling mill in the early part of the 20th century and later becoming the first UK company to start electrical-contact welding in the 1960s. With innovation at its heart, STL continues to lead the way with its unique combination of design capability, tool precision and manufacturing efficiency. This has enabled the company to project lead and manufacture leading edge components for the smart metering industry and focus on new areas in the growing EV market.
With a continual focus on research and development (R&D), and in the context of aiming to deliver more environmentally friendly, net zero-targeted solutions, STL and the TPT team identified a gap in the market for the manufacture of aluminium and copper bimetal connectors for the electric vehicles (EV) market in the UK and Europe. These are particularly challenging to produce because current processes for joining the two metals together can result in the formation of excessive amounts of weak and brittle intermetallic phases, adversely affecting the structural integrity of the part. Therefore, it would require innovative thinking to create a new thermal processing technique.
TWI Industrial Member company STL had been considering for some time how to produce bi-metallic busbars, typically housed inside switchgear, panel boards and busway enclosures, for the EV sector. Busbars are used to connect low voltage in battery banks and high voltage equipment at electrical switchyards, as well as for high current distribution.
STL and TWI then met at a conference held at TWI Cambridge, during which the two parties had an initial conversation about how they could potentially work together. STL had a tour round TWI’s engineering halls and a follow-up meeting with TWI’s TPT team was arranged. This enabled STL and TWI to identify topics of mutual interest, and STL explained their ambition to develop a new thermal processing technique for use in manufacturing busbars.
Consequently, the STL and TPT team conceived the idea of using an integral bonding approach instead of laser welding or wire bonding, both of which are used to produce connectors for the EV sector but known to have limitations. These include poor reliability caused by the number of joints required and the resultant heavier than desirable component weight, and the quality of joint achievable. When welding copper to aluminium or vice-versa, the aforementioned intermetallic phases will form, however, by making a bi-metallic strip, manufacturers can simply join copper-to-copper at one end and aluminium-to-aluminium at the other. The TPT team then explored different ways of instigating such a project, which in turn led to the decision to bid for an Innovate UK Smart Grant. If successful, this would provide the funding for the initiative.