How a new hybrid approach to titanium manufacturing is boosting UK aerospace opportunities.

Superplastic forming (SPF) is a near net shape manufacturing method for producing thin-sheet metallic components, and is typically used to create complex-shaped titanium parts used within the aerospace sector. Now, a new hybrid approach to the manufacturing process is poised to boost capability in the UK market and increase manufacturing efficiency for key aerospace components.

The project forms part of the National Aerospace technology Exploitation Programme (NATEP), and is led by Shropshire-based lightweight engineering firm SDE Technology. Supported by the Advanced Forming Research Centre (AFRC) within the National Manufacturing Institute Scotland (NMIS) Group and industry collaborators Boeing and Timet UK, SDE Technology is leading the development of a new hybrid SPF process that makes use of innovative new tooling to enable a significantly reduced process time.

A HYBRID APPROACH
SPF is a specialised manufacturing technique used to mould highly ductile metals, such as aluminium, titanium and certain steel alloys, into complex shapes by exploiting their superplastic behaviour.

“In this process, a metal sheet is heated to a high temperature where it becomes extremely malleable, typically between 40-70% of its melting point,” explains Les Gill, member of SDE’s Technical Advisory Group and principal consultant at TaBA Associates. “The softened metal is then placed into or over a mould and shaped using controlled, pressurised gas to stretch and form it to the desired contours. Once formed, the metal is cooled under pressure to maintain its new shape. The economics and precision of this manufacturing approach is highly valued in industries such as aerospace, defence and even in automotive for creating lightweight, intricate components that are structurally robust, reducing material waste and assembly requirements.”

SDE’s new hybrid technique is estimated to shorten the forming cycle time by over 50% and cut the manufacturing cost by as much as 25% when compared with traditional superplastic forming processes. In terms of applications, the manufacturing method is capable of streamlining the production of a wide range of critical aerospace parts.

“SPF is an ideal manufacturing method for aerospace components, especially suited to create intricate, lightweight parts that offer enhanced structural integrity and performance,” Gill says. “Typical applications include fuselage panels, which benefit from seamless, aerodynamic surfaces; wing components like skins and flaps that require precise, lightweight shapes for efficient flight; and engine components such as fan blades and inlet cones, made from heat-resistant alloys. SPF is also used for creating robust door frames, internal structures like bulkheads and brackets, and even seat frames, all of which contribute to reducing overall aircraft weight while maintaining strength and durability.”

According to Gill, the method streamlines production by integrating multiple features into single components, significantly reducing assembly requirements and material waste.

SIZE MATTERS
While SDE’s hybrid SPF technique promises many benefits in terms of shortened forming times and reduced material waste, like any manufacturing technique it is not without its limitations.

“SPF does has size limitations on the parts it can produce, primarily dictated by the capabilities of the equipment used and the physical properties of the materials,” Gill explains. “The limitations are in common with other material processes where the size of the furnace is a critical factor. Also, the larger the parent sheets then the more complex and robust machinery is needed to handle and maintain uniform temperatures and prevent material tears. Additionally, ensuring even pressure application across large surfaces necessitates advanced control systems, and the size of the tooling and dies also sets limits on the part dimensions. However, technological advancements are continually pushing these boundaries, enabling the production of increasingly larger components and should be reviewed on a case-by-case basis.”

SUPERCHARGED POTENTIAL
As part of the NATEP project, further funding has been secured to evaluate the carbon footprint of the new process, which could be cut significantly due to shortened heating and forming times, as well as using lower temperatures of around 800°C. Additionally, when exposed to high temperatures during SPF, an oxide layer is formed on titanium components – known as alpha case – which requires powerful acids to remove. The new SPF approach uses less heat and, therefore, also reduces the layer thickness and associated time spent to remove it.

Project partner AFRC has previously investigated the hybrid technique, and now this latest collaboration is exploring how the process can be scaled up for the aerospace sector’s industrial needs.

“Our team has a combined 200 years of experience in material science, modelling, and SPF, which makes us well-placed to support the development of new techniques that could make a big impact on the entire aerospace industry,” says Evgenia Yakushina, Forming Team Lead at AFRC. “This work has the potential to unlock opportunities for manufacturers to offer improved, quicker methods of producing key parts for aircraft. So far, the research has demonstrated huge potential with important parallels between the new hybrid method and the traditional approach already evident.”

NEXT STEPS
The commercialisation process of the hybrid SPF technique has already begun, with SDE leading the industrialisation of the manufacturability of components using this process. This has fine-tuned the SPF process for a variety of materials and applications, and seen it protected by intellectual property rights.

“Market analysis identified key industries, such as aerospace and automotive, where SPF’s unique capabilities offer significant advantages,” says Gill. “SDE has started to communicate the unique benefits of this SPF, such as the cost effectiveness of the process versus the non-SPF process, bringing in scope much needed economies whilst delivering superior quality and design capabilities, ensuring a strong market presence.”