UK additive process used to make titanium pressure vessel for space

An additive manufacturing process pioneered by engineers at Cranfield University in the UK has been used to produce a full-scale prototype of a titanium pressure vessel for use in future manned missions for space exploration.

titanium pressure vessel
The full-scale prototype titanium pressure vessel. Image: Cranfield

The piece – which was produced by engineers from Cranfield, Thales Alenia Space, and Glenalmond Technologies – is approximately 1m in height and 8.5kg in mass.

Made of the titanium alloy Ti-6Al-4V, it has been deposited using the Wire + Arc Additive Manufacturing (WAAM) process, which Cranfield University has pioneered over the last decade.

Thanks to being able to go straight from digital drawing to final structure, WAAM has integrated two individual pieces into a single part; eliminating the need for long-lead-time forgings, and substantially reduced the amount of waste material removed by machining.

The process has also enabled the team to significantly reduce the mass of the final components and the Cranfield team is now working on methods to deposit closer to the final thickness.

The WAAM shape was manufactured at Cranfield and then sent to Glenalmond Technologies where it was stress-relieved, laser-scanned, machined and inspected using an ultrasonic method. Final inspection was performed by Agiometrix using a computer tomography (CT-scan) for internal quality analysis and an optical scanner, with Thales Alenia Space ensuring that the part met the mechanical requirements and specifications.

The team is now building of a second prototype in order to carry out fine tuning of the whole manufacturing cycle, to demonstrate the repeatability and reliability of the process, and to push the implementation of the new approach into the flight hardware.

Eng. Massimo Chiampi, study manager for additive manufacturing projects at Thales Alenia Space, said: “We were looking for an innovative manufacturing solution for the tanks, which typically suffer from long lead time with the conventional production route based on subtractive machining. Thanks to this project, we have demonstrated that the adoption of WAAM technology enhances the competitiveness of our product. A near-net-shape item is fabricated in few days – compared to several months needed for the procurement of the standard wrought products – and also the amount of machining operation is consistently reduced. We have achieved a 65 per cent reduction on the overall lead time without giving up the requested performances and this provides a benefit also in terms of design flexibility, making it possible to answer customer needs at a late stage of the project.”

Dr Filomeno Martina, senior lecturer at Cranfield University and CEO of WAAM3D, said: “This part was built using software and hardware that has been developed over the last decade; these are finally ready for commercialisation through a new spin-out company from Cranfield, WAAM3D.

“This part has given us the opportunity to test WAAM3D’s innovative solutions on a high-profile user case, with a very aggressive timescale. We are very proud of the level of automation achieved at Cranfield University. WAAM3D will make all these tools available to industrial community in the next couple of months and we are looking forward to the impact on industrial large-scale additive manufacture this will have.”

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