Back to the Future

3D printer - USS Essex
In July 2022, a 3D printer capable of printing aluminium parts up to 10x10 inches was installed onboard Wasp Class amphibious assault ship USS Essex. (USN)

Can Additive Manufacturing processes really deliver useful support to deployed naval vessels?

On 1 August 1785, Jean François de Galaup (comte de Lapérouse) set sail for his famous expedition around the world. The mandate was clear: over the next four years, Lapérouse and his crew were to continue mapping coasts and islands around the Pacific. To this end, the expedition comprised two frigates – La Boussole and LAstrolabe – with 220 crew onboard and… 2,000 tons of materiel. Sets of sails and canvas, raw pine wood, capstan, anchors, chains, pulleys and ropes were all essential elements to renew the rigging entirely, if necessary, during the journey.

The increasing complexity characterising navy ships today would make it impossible for Lapérouse to strive for the same level of logistics autonomy. Instead, when know-how and/or spare parts are not available onboard to repair potential damage; ships have to call on ports where they can get the necessary logistics support. Additive Manufacturing (AM) – also known as 3D printing – is often seen as the magical solution to the logistic burden of extended deployments away from home ports: with one machine, crew can print spare parts and repair damages. Yet while it holds much potential, several challenges must be addressed before AM can deliver on its promises.

AM 101

The ISO/ASTM 52900:2021 defines AM as “the process of joining materials to make parts from 3D model data, usually layer upon layer.” By ‘layer’, the standard refers to material that is being laid out to create a surface.

To date, as noted in the ISO document, there are seven AM processes. Each of these processes is suited to different types of materials and applications, Guillaume Rückert, senior expert in Metallic Materials Manufacturing at Naval Group, told Armada International (AI): “Each type of material can take different forms, such as wire or powder, and depending on what is being used for which purposes the process will be different.” For instance, while binder jetting – joining powder through a liquid bonding agent (or powder bed fusion) – fusing regions of a powder bed through thermal energy – are suited for powder, while Wire Arc Additive Manufacturing (WAAM) is designed to work with wires.

“Experimentation with AM by individual customers [armed forces], offices and companies has been ongoing for a few years,” Matthew Caris, senior director at Avascent, told AI. And while navies have been slower in their adoption of the technology compared to land and air forces, over the past couple of years the pace of progress has picked up.

As is often the case, the US Navy (USN) has been leading the way, making significant strides over the past year. In July 2022, a 3D printer capable of printing aluminium parts up to 10×10 inches was installed onboard the Wasp Class amphibious assault ship USS Essex. The testing took place during the Rim of the Pacific (RIMPAC) exercise and aimed to demonstrate AM’s added value in increasing naval forces’ autonomy at sea. Shortly after, in October 2022, the USN opened its first Additive Manufacturing Centre of Excellence, based in the Centre for Manufacturing Advancement on the campus of the Institute for Advanced Learning and Research, Virginia, USA. The centre will feature three bays in order to facilitate scaling up of AM activities and serve as an operational hub. Finally, in November 2022, the first metal 3D printer was installed on Wasp class USS Bataan.

3D printer - USS Bataan
Officials coordinate the on load of a 3D printer aboard Wasp-class ship USS Bataan. (USN)

The USN may be leading the way, but the French Navy (Marine Nationale) is following closely and, together with Naval Group, it has been carrying out a number of experiments. Two of its Mistral class amphibious assault ships – Dixmude and Tonnerre – carried a 3D printer based on polymeric melt-wire AM processes. Over 145 days, 150 parts were printed onboard the Dixmude, of which nearly 60 percent were for living and recreational purposes, while approximately 20 percent were technical parts, according to a paper published by the FRS in June 2020, The development of 3D printing in the Armed Forces: a breakthrough innovation?. Additionally, since February 2019, a similar 3D printer has been installed onboard the Charles de Gaulle aircraft carrier and, in early 2020, the first Rafale took flight from the aircraft carrier with a 3D printed control unit for emptying fuel tanks. Finally, in 2019 Naval Group successfully printed a propeller for the Tripartite class mine hunter, Andromede. Featuring five 1,100lb (200kg) blades, the WAAM printed piece was certified by Bureau Veritas.

Over in the Pacific, the Royal Australian Navy’s (RAN) approach to AM has also progressed through a series of small pilot innovation programmes and proof of concept activities ashore and afloat. More specifically, an Australian defence spokesperson told AI in a written statement that starting from 2017 one of RAN’s priorities was to get entry-level plastic printers onboard its ships. In parallel, it has also worked on evolving both policy and knowledge base in order to facilitate AM’s operationalisation. “Trials and exercises have proven the potential of basic AM, but an enterprise-level implementation demands deeper coordination,” the spokesperson noted.

Naval Group successfully printed a propeller
In 2019 Naval Group successfully printed a propeller for the Tripartite class mine hunter, Andromede. (Naval Group)

What can AM do for you?

When looking at the AM projects implemented by the USN, the French Navy and the RAN – a small sample of the breadth of ongoing research worldwide – one of the main advantages AM can bring to navies is operational autonomy. Yet AM actually presents a vast potential that could span across the whole lifecycle of a Navy ship.

Even before moving into construction and production, AM can bring significant benefits to the design phase of naval systems and parts. First, because it works by adding layer upon layer, AM opens-up new possibilities in terms of shapes. “Having a certain degree of freedom is key to creating innovative shapes,” Alexandre Astruc, head of Section Metallic Materials and Coating at Bureau Veritas, told AI. “The process of AM favours the conceptualisation of geometrically optimised designs that can, for instance, result in lighter parts.” Naval Group, for instance, is experimenting with the development of hollow propeller blades, which would improve propeller performance by virtue of being lighter. “Perhaps just as interestingly, lighter blades could allow us to add damping loads so as to improve propeller acoustic discretion,” Rückert pointed out. Furthermore, as noted in the DoD strategy, AM opens the possibility to combine many parts in single assembly, reducing part count, manufacturing cost and weight “while improving system reliability.”

AM can also contribute to “drastically lower the cost and complexity threshold for the production of test-ready prototypes,“according to the Australian Defence spokesperson. The ability to print-out prototypes at a faster rate and lower cost eliminates the burden of having a perfectly locked in design from the start. “This, in turn, opens-up the opportunity to iterate on the design with the customer and refine it over time,” Kelleigh Bilms, senior director at Avascent, told AI. Additionally, as noted by Caris, easier prototyping could avoid the design of parts and solutions that “are not conducive to production,” thus significantly reducing overall design and production costs.

In fact, another key advantage of AM at production level is that it lowers the scrap factor. “While the operator may need to carry out some light machining to smooth-out the printed part, the printing process produces few scraps,” Maxime Leprince, Welding Engineer at Bureau Veritas, told AI. This is of particular interest when exotic and expensive materials are used for 3D printing. “Consider the titanium used for aircraft engines,” Bilms said: “when the original scrap factor is approximately 70%, the use of a 3D printer would bring considerable cost benefits.” Additionally, because 3D printing allows for in-process inspection – non-destructive inspection of parts during the production process – it prevents the production of parts that are not fit for purpose. “The identified faulty piece is fixed immediately, rather than scrapped at the end, as it sometimes happens,” Leprince added.

Finally, at operational level, AM’s key benefit is the reduction of the logistics footprint on missions. First, as noted by Martin Huber, Project Officer Logistics at the European Defence Agency (EDA), defence materiel – especially naval – is often used for years – decades – before being replaced. Yet spare parts and associated maintenance tools may no longer be available. “3D printing would allow armed forces to print rather complex parts and tools themselves,” Huber highlighted. Furthermore, when receiving new assets, armed forces need to secure a minimum amount of spares. However, logistic supply chain and warehouse, as well as associated staff and procedures, are all costly and time-consuming. The use of AM would, once again, reduce costs and burdens for navies. Finally, AM could also allow navies to break defence primes’ control, which is often associated to service contracts.

Secondly, “when combined with trained personnel and agile field engineering, AM enables the forward production of stores items and supports the Battle Damage Repair [BDR] that is needed to keep equipment in the fight, even in a conflict,” the Australian Defence spokesperson wrote. A statement supported in unison by Bilms, Caris and Huber.

What can you do for AM?!

Yet for all its promises, AM remains a rather new technology. Mature enough to have an emerging market, as noted by Huber, there are nevertheless a number of hurdles that need to be address before it can deliver full autonomy – from continental logistics chains and primes.

And the first hurdles present themselves even before a part or solution is even designed or produced. “One of the first challenges we face is understanding all the eligible materials and carefully matching them with the best process according to part specifications,” Rückert said. Each part presents specific challenges and opportunities and, as indicated in GE Additive’s playbook, ‘Building the Business Case: Identifying Criteria to Measure ROI for Additive Manufacturing’, one must “evaluate multiple parts for their level of complexity and assess which ones deliver the best ROI [Return On Investment] from design freedom, less labour and more efficient use of materials.”

Additionally, Rückert told AI that aiming to recreate in 3D a part’s identical twin is not desirable because material and process constraints need to be taken into consideration. As such, Naval Group is currently working on a software solution it will be able to offer its customers to help their decision-making: first the software will help identify the potential material to be used for the specific piece, then it will support them in choosing the best process according to certain technical and economic criteria.

On the production side, Bilms explained that while there is a lot of focus on maturing the technology – both at armed forces and industry level – “the biggest skepticism is on testing and qualification.” Any 3D printed part will have to undergo the same qualification and testing processes as those manufactured through traditional processes, which can be costly and time consuming. In agreement with Bilms, Caris added that currently in the USN much of the experimentation is on printing aircraft maintenance parts, and truly integrating AM in defence will be a cultural challenge. “If you can only use AM for non-critical parts or parts that will only operate in non-stressful environments, then it may be a point of entry to build trust in the process,” he said, though this will take time.

As for bringing 3D printing to the tactical edge and facilitate BDR, the road ahead remains long – and possibly rather winding. Ships evolve in a complex, unforgiving environment. The type of material used to print the spare parts will have to be stored adequately to avoid being compromised by humidity. The type of process used will have to take into account ship’s motions while the printing process is ongoing; “for now, it looks as though 3D printing onboard can mainly be done in quiet seas or at harbour for complex parts,” Huber added. Certification and qualification of the parts might have to be done on a case-by-case basis, as long as standards are in the making, “however currently return on experience is limited, so discussions on ISO standards are ongoing but at a very slow pace,” noted Astruc.

Another significant hurdle will be the extent to, or modality in, which armed forces will be able to use original design files to print parts. Firstly, maintenance contracts are an important part of the procurement process, and where industry stands to make the best ROI on each programme. Allowing navies to print their own spare parts would considerably reduce such revenue stream. One solution to the issue would be for industry to understand how to deal with the Intellectual Property (IP) rights. As Huber discussed: “Would navies pay for each file upload? Would they pay for a license fee for a certain number of print parts [a sort of equivalent to maintenance contracts]? Or would the cost of IP rights be part of the procurement process?”

Secondly, being able to download files means ensuring secure end-to-end data transfers to avoid any interference and tampering with the original files – which could severely compromise parts and systems. To this end, the DoD’s AM strategy presents a goal called “Secure the AM flow” aimed at ensuring “cyber security throughout the AM workflow, to secure the digital thread which includes the creation and transfer of data, as well as the protection of the AM production and testing processes.”

Ultimately, “printing is only one small part of a much bigger process,” Rückert highlighted. A process that starts with design constraints and important ROI considerations and ends with the adequate training of crew onboard.

Back to the Future

There is no doubting that AM can bring considerable benefits to navies throughout the whole lifecycle of their solutions. From allowing far more design freedom than traditional manufacturing techniques, to decreasing production costs and bringing increased autonomy to the tactical edge, both industry and navies have much to explore. Yet multiple hurdles remain to be addressed and a number of potential benefits remain aspirational to date.

The work being carried out in countries including the US, France, Australia and, to a certain extent, the UK, show that defence culture is willing to change and potential benefits far outweigh current challenges. In January 2021 the US Department of Defence [DoD] released its first ever Additive Manufacturing Strategy. Focused on key benefits and challenges for the integration of AM at armed forces level – including training, cyber security and IP rights – it no doubt benefitted from the US Marine Corps’ (USMC) Additive Manufacturing Policy, published in March 2020. Similarly, France’s land forces have been experimenting with plastic AM in Gao (Mali) and N’Djamena (Chad) since 2019 to: carry out a cost-benefit analysis of different AM processes; and, to implement a blockchain so as to address issues of IP and industry revenue, as well as guarantee file integrity to foster trust in the process.

At European level, the European Defence Agency(EDA) has been setting up a number of initiatives in the past few years to support armed forces and industry in the promotion and integration of AM in defence. This includes supporting as well as organising demonstrations and workshops to provide a space for armed forces, industry and academia to meet and discuss on a regular basis. Beyond defence, the participation of industry partners such as Bureau Veritas M&O to projects such as Grade 2XL – funded through the Horizon 2020 EU programme – can also bring significant advancements to use of AM to support navies. Grade 2XL seeks to increase the capability WAAM can deliver in terms of durable engineering structures.

When all is said and done, “one can hypothesise that the design/production side will take off first because that is where we are seeing investments and where there are fewer conflicts of interest,” Bilms concluded. One aspect that could eventually contribute to growing adoption of AM across industry and navies is its potential for enhancing sustainability. From the freedom to design more efficient propellers, to the ability to use different materials on a single piece – e.g. strong, lighter material coated with anti-biofouling and non-corrosive material – and, ultimately, to a considerable reduction in logistics transports and costs, AM could play a significant role in greening navies.

“Looking at the logistics benefits AM can bring is, in a way, like going back to the future for navies,” Caris concluded: “sustaining ships that are deployed further and further away from their home bases is in navies’ DNA.” Lapérouse would have approved…

by Dr. Alix Valenti