The rise of additive layer manufacturing (ALM), more commonly known as 3D-printing, has sparked a great deal of enthusiasm in recent years in the tech community, and across manufacturing industries more broadly. Now becoming an increasingly accessible technology, it has yet to achieve its full potential, notably in the aerospace and defense (A&D) industries, where expectations have perhaps been overly optimistic.
Some of the financial projections realized in the last years about the market potential of ALM have undoubtedly contributed to this excitement: in 2020, the Israeli consultancy Smartech foresaw a total market of $6.74bn by 2026 for ALM business in A&D, representing 15 to 20% of the entire 3D-printing market. As encouraging as these figures may be, they should not obscure, by overplaying them, the actual magnitude of change that ALM is bringing to these sectors. To understand the limitations faced by this technology at this juncture, one must look beyond prospective profits.
Sure, 3D-printing is becoming more mature, with significant progresses still unfolding in fields like “advanced” metal additive manufacturing. Yet, A&D manufacturers are only integrating this technology into their processes through small steps, and the announced revolution in supply-chains and products designs is still far off on the horizon. A quick glance at applications in aviation, space systems, and defense, is a good starting point to cast clarity over the current state of AM techniques in A&D.
Gradual developments in aviation
The potential for 3D-printing in aviation is often advertised, not least due to the critical importance of metals in the fabrication of an airplane. It is for instance estimated that over 50% of the mass of advanced aircraft engines consist of nickel- and iron- based superalloys; not to mention the importance of titanium alloys. ALM (and metal-ALM in particular) is expected, among others, to minimize waste of raw materials; to reduce the weight of aircraft parts; or to enhance their physical and mechanical properties, thus bringing gains of time and efficiency, and reducing overall costs.
Such expectations are understandable, but metal-ALM techniques find few critical applications in aviation for now, remaining rather circumscribed to the production of non-loadbearing parts, and R&D efforts. It is no surprise if last February, Airbus and Safran partnered (along with 11 other companies) to try and further the use of metal 3D-printing in manufacturing processes. No surprise neither if Chinese OEM COMAC claimed, as early as in 2013, to have produced the world’s largest 3D-printed titanium loadbearing component for its C919 airliner, yet never communicated about any test flight of the aircraft comprising such major 3D-printed critical components.
Sure, some encouraging developments made the headlines, such as the use of over 300 3D-printed parts in the General Electric GE9X engine powering Boeing’s 777X jet during its maiden flight, or the fabrication by Safran and GE of a 3D-printed, single-piece fuel nozzle for their LEAP engine. Leonardo is also making progress supplying flight-ready parts for its helicopters. Still, when looking at aviation, the overwhelming majority of ALM applications concern non-critical components. And for now, successes in 3D-printed engine components seem to be the exception which proves the rule, rather than a compelling, actionable proof-of-concept on a large scale.
Encouraging perspectives in space applications
The space industry may however beg to differ with this careful stance. In this sector, innovations stemming from potential applications of AM range amongst those blurring the boundaries between sci-fi and reality. As exciting and promising as such perspectives may be, however, micro-gravity-ALM is unlikely to enable autonomous robots to print spares in space for satellites (or satellites of their own) on the short- or medium-term. Nor is it going to bring a miraculous solution to the innumerable complexities of establishing a Lunar or Martian Space Station, before a little while.
Still, the space industry may well be the fastest-developing area for ALM applications across A&D sectors, with recent advances and ongoing projects going slightly further down the 3D-printing path. Some of the leading space OEMs have been using this technology for quite a long time now: SpaceX, for example, has been a pioneer in the field, incorporating a 3D-printed combustion chamber into its SuperDraco thruster back in 2013.
More recently, Boeing has committed to using AM to produce and deliver critical components, be it for large spacecraft such as the US Space Force’s Wideband Global SatCom, or for small satellites, with a new dedicated facility to be built soon. Similarly, Airbus managed to mass-produce radio frequency components for its Eurostar Neo satellites through large use of ALM.
The most impressive progresses however come from newer, smaller players. In January 2022, the Australian startup Fleet Space announced its intention to start deploying a constellation of 100% 3D-printed satellites (called Alpha) by one-year time. In August, the California-based Relativity Space completed a static fire test of the first stage of its Terran 1 rocket, ahead of the announced launch of Impulse Space’s Mars Cruise Vehicle and Mars Lander, meant to take place between 2024 and 2029.
Strong momentum for ALM in defense
Armed services have heavily invested in 3D-printing, through the definition of strategies on the matter, constituting ALM capabilities of their own, or pushing their suppliers to adopt this technology in their manufacturing processes. The US Secretary of Defense’s Office for Research and Engineering, for instance, issued its first-ever comprehensive “Additive Manufacturing Strategy” in January 2021. On the other side of the Atlantic, the European Defence Agency organized its first European Military Additive Manufacturing Symposium in October 2021.
Some ambitious projects and compelling achievements can be found across the multiplicity of use-cases observed in defense these last years. In July 2021, the US Army unveiled its plans to build the largest metal 3D-printer ever, purposed to print hulls for combat vehicles.
On the naval side, among the many recent advances (such as in unmanned underwater vehicles or small logistics vessels), an important step was achieved in France, with the development by Naval Group of a 3D-printed propeller for the minehunter Andromede.
Back in 2019, Naval Group had already embarked a small 3D printer on a helicopter carrier, and in 2020, a Rafale-M from the French Navy flew with a part 3D printed aboard the Charles de Gaulle aircraft carrier. Another advantage brought by ALM is flexibility, as observed in Ukraine with UAV-dropped bombs comprising 3D-printed parts such as tail fins to stabilize their fall.
The area with the greatest potential for ALM in defense over the short- and medium-term, nevertheless, is certainly MRO. Many countries have already adopted AM to this end, though to a limited scale only. The objective recently set by the French weapons procurement agency to reach 10% of 3D-printed spares for ground forces by 2025, gives a sense of the long way ahead.
However, the adoption of AM for the provision of small spares is already well underway, as demonstrated by the several instances of embarked 3D-printers on major ships (USS Essex, Charles de Gaulle French carrier, but also Chinese warships, among others). Such use-cases have often been coupled with the implementation of blockchain-based inventories, to enable swift communications with suppliers while on operations.
A&D AM slowly overcoming enduring obstacles
Though clearly encouraging, this picture of the current state of ALM throughout A&D is therefore contrasted. It is quite obvious that one should not expect to see 3D-printers undertaking a major role in manufacturing processes in the near future. The revolutionary potential of this technology, if any, is rather to be found in the extremely vast array of existing and imaginable applications. In most cases, ALM is likely to bring a multiplier effect to existing activities, be it in an industrial context (e.g., by modeling complex shapes previously impossible to manufacture, cutting some of the manufacturing costs and reducing lead times for some spare parts), or even in an operational context (as demonstrated in Ukraine, but also in the past years on theatres like Sahel or Afghanistan by the French and US Army respectively.
Still, many obstacles remain, be they of technical, regulatory, or economic nature, hampering a widespread deployment of AM in A&D:
Looking first at the technical side of things, AM is not yet technologically mature in every aspect. Progresses in metal AM in particular, though progressing at a fast pace, are still unfolding, as underlined last year by the Director of the French Army’s MCO service at a Parliamentary hearing: “The real challenge here is to move to metal printers. Then, the issue will be to get parts qualified.”
Qualification and certification are indeed yet another major challenge in the induction of AM into A&D. These industries are manufacturing highly complex systems, and have to respect extremely rigorous technical standards. Talking about the use of AM for military MRO in operation, the French academics Alexandre Taithe and Bruno Lassalle stressed that these limits, “whether technical or about certification, stem from the application of AM to equipment that was not initially designed to be maintained, at least in part, with this technology.”
From an economic standpoint, finally, there is an issue with the commercial viability of a thorough inclusion of AM into existing business lines. While 3D-printing is considerably cheaper and more flexible when it comes to manufacturing individual parts, the cost of large-scale production would hardly be sustainable (let alone interesting to A&D firms), AM production rates being capped at rather low levels. In addition, a rapid implementation of AM is made virtually impossible in the short-term by the long industrial cycles of A&D.
All in all, much remains to be done before we see the advent of an aerospace industry leveraging the full potential of AM. The numerous achievements observed these last years are surely very promising; it would be wise, however, to keep a certain distance from the most bombastic announcements.