Why are Aerospace & Defense Companies Embracing Additive Manufacturing?

To embrace additive manufacturing or not?

It’s no longer a question of when metal additive manufacturing (AM)—and particularly metal laser powder-bed fusion (LPBF)—will become an accepted, reliable production technology, particularly in aerospace and defense. This is already the case now. Over the past 18 months a host of aerospace leaders, OEMs, startups, and contract manufacturers (CMs) alike have purchased, or begun outsourcing work to, advanced AM systems. They’re confidently producing end-use, 3D-printed parts—and sometimes entire rocket engines.

In a quarterly study of revenue growth of leading AM system-makers, published in the summer of 2022, the industrial sector was reported to have grown 19 percent compared to the same period in 2021. This was cited as proof that companies and users are looking to invest in the larger, more powerful industrial AM solutions that offer greater efficiency and productivity.

A cross-sectioned thrust chamber printed in GRCop-42, a copper/chromium/niobium alloy designed for high-strength dispersion and high conductivity. The chamber walls contain internal channels for regenerative cooling. This material was developed by NASA for use in regenerative rocket engines. It is shown here as-printed (L) and polished (R).

Pratt & Whitney, Lockheed Martin, SpaceX, Honeywell, and others, for example, have clearly come to the realization that the technology is capable of delivering mission-critical products. SpaceX in particular is on a fast track with additive, with more than 10 systems installed.

And it’s not just the biggest names buying into AM; “New Space” startups like Launcher and Aerojet Rocketdyne are finding that they can purchase a machine or two, develop proprietary designs, and deliver competitive rocketry in astoundingly short periods of time. What’s more, many CMs that serve aerospace and defense customers—including Wagner Machine, Vertex, Hartech Group, and Knust-Godwin—have also been actively integrating AM systems into their machine shops in response to customer demands for highly sophisticated parts that can’t be made any other way.

Many items on the wish-lists of the aerospace and defense industry are now being particularly well-served by advanced additive systems: Lightweighting through part consolidation using an ever-widening selection of superalloy powders qualified for 3D printing. The ability to not only print exactly what’s desired without compromising on design, but improved performance metrics provided by complex internal passageways; low-angle, support-free blading and tubing; and “impossible” geometries not previously imaginable.

AM in Commercial Aviation

Large 21-inch (535 mm) diameter stator ring featuring low angle blades and internal cooling channels. In a jet turbine, the stator element contains blades or ports used to redirect the flow of fluid. Part shown as-printed. This part was printed on a Velo3D Sapphire XC machine, which is capable of printing parts 600 mm in diameter and 550 mm in height.

An understandable abundance of caution related to human flight has resulted in a regulatory environment that has slowed commercial aviation’s move towards adoption of AM to some extent. Although a variety of 3D-printed parts have been certified by major players in that industry—GE aircraft engine components are the best-known example—this has involved many years of proprietary development time and considerable expense (FAA 14 CFR 21.1 permits airframe, engine, and propeller manufacturers to make AM parts, with exacting certification requirements).

A volute developed by Launcher for its E-2 engine. The component is a closed-cycle 3D-printed, high-performance liquid rocket engine in development for the company’s Light launch vehicle.

However, last year’s announcement of an MMPDS (Metallic Materials Properties Development & Standardization) materials spec, for Alloy 718, an Inconel™, is a step toward levelling the field for aviation-related companies of all sizes. MMPDS is an industry-based source for design allowables recognized by the FAA, DoD and NASA. Inconel is the first of several materials (aluminum and titanium are next) being evaluated for use with 3D-printed parts and repairs.

This, in turn, is increasing the value of AM to commercial aviation for supply chain “fixes,” i.e., when a casting shop no-quotes a legacy part, or lead times for a replacement are astronomical. LPBF technology can help offset the high costs of low-volume, direct-part replacement of conventionally produced parts when demand and long-term forecasting are uncertain. This significantly impacts the economics of future Maintenance, Repair & Operations (MRO) projects.

3D-printed parts must provide inherent value because they are 3D-printed. For example, with complex gas turbine combustor components with optimized interior geometries—that will have limited aftermarket availability or high replacement cost—AM can enable a CM to produce hardware for its customers on-demand, negating the high NPI (new product introduction) tooling costs and lead-times of other methods.

AM in Aerospace and Defense

On a faster pace than commercial aviation, unmanned space flight, satellite launch, hypersonics R&D, and drone production have been leaping ahead with metal AM in the past few years. Applications include monolithic, nozzle/combustion chamber combinations that consolidate large assemblies of parts into one, as well as impellers, stators, fuel tanks, pump housings, complex tubing, and lightweight microturbines.

A typical conventional-to-AM conversion might focus on a scavenge-tube component that dips into an engine sump for oil recirculation. The original is made up of eight separate parts, welded together; moving to AM consolidates those into a single component, eliminating eight potential sources of variation, and bypassing extended time spent in welding and brazing.

Now-20-year-old rocket designer Ewan Craig with his aerospike engine (right). Part consolidation made possible by advanced metal laser powder-bed fusion enabled the high schooler to design a multifunctional component that was 3D-printed as a single piece.

Another example is a microturbine for a drone. An original design for conventional manufacturing had 61 parts; the AM version consolidated them into just one. Purdue University has recently announced work on hypersonics propulsion—of understandable interest to the Department of Defense—using 3D-printed parts.

The quality of product now achievable using advanced LPBF systems, combined with the economics apparent in these examples, are making the case for AM much clearer.

Outsource to CMs First, Then Taking AM In-House

The larger names in aerospace have started to invest in AM in a big way. SpaceX has certainly taken the lead, as mentioned, and others are announcing their intentions to increase their commitment to the technology. Many begin exploring AM by outsourcing to contract manufacturers with expertise in 3D printing and finishing; later, they may purchase AM systems for direct use in their own facilities.

Now that the more advanced systems are delivering on the AM promise of geometric flexibility and precision, OEMs are seeing significant acceleration in their development programs. This summer, Pratt & Whitney, part of Raytheon Technologies, purchased a Velo3D Sapphire system (which includes print-preparation software, the printer itself, and embedded monitoring and quality control software). P&W is evaluating the technology for manufacturing production jet-engine components for their GTF™ and advanced engine programs.

P&W are experienced users of AM, much of which they’d been outsourcing to contract manufacturers for printing and finishing. While they plan to continue taking advantage of that resource, their newest system will be located in-house at the Raytheon Technologies Research Center. Raytheon is a launch participant of President Biden’s AM Forward initiative.

Lockheed Martin has also recently added an advanced LPBF system to its Additive Design & Manufacturing Center, which pilots new AM technologies for production deployments in the company’s Space division.

Upstarts Start Up With AM

In the innovative world of aerospace, size of company matters less than in the past when AM is part of the picture. Smaller enterprises such as Aerojet Rocketdyne, a supplier to NASA; Launcher, a satellite-launch startup; even a teenage schoolboy whose one-piece aerospike engine is soon to undergo ignition testing—all of these have achieved headlines in the past year thanks to 3D printing.

  • Aerojet Rocketdyne has been providing NASA with 3D-printed end-use components for a variety of projects, among them the massive RS-25 engines that will carry the Artemis mission to the Moon (with a goal of placing the first unmanned Orion lunar module into orbit this year) and later Mars.

    NASA has half the budget than it did in the 1960s; recent progress is due, in no small part, to advances in 3D printing. According to James Horton, aerospace engineer and mission architect at Aerojet Rocketdyne, “As with any complex endeavor, the more affordable you can make it, the greater the chance that you will ensure its completion. Metal AM plays a key role in achieving these goals.”

    Using AM, Aerojet Rocketdyne has been able to drive down propulsion costs, speed up time-to-market, and improve the performance of its products. Most recently, the company employed advanced LPBF to overcome the limitations of an earlier injector design for the RS-25 engines that will carry the Artemis mission into space.

    This time they were able to make the injector out of lighter-weight titanium instead of the original Inconel, resulting in a thruster that is 1/5 the mass, 1/2 the size, and 1/3 the cost of a conventionally manufactured version. Since the newest model contains far fewer components, it’s also easier to assemble, with much less chance of failure during operation. Said Horton, “We’ve shown that, by leveraging additive manufacturing and advanced software technology, we’re able to interject affordability, reduce lead times, and greatly improve upon system performance compared to the way we built parts in the past.”

  • Another young company, Launcher, intended from the get-go to take advantage of AM as it built up its low-cost, small-satellite-launch program. Earlier AM systems they were using required significant redesign work and post-processing. But the more recent purchase of one of the newest LPBF systems provided the level of technology needed to fulfill a rideshare opportunity with SpaceX.

    Launcher was able to shift priorities from developing its own rocket to completing the production of their Orbiter satellite-transfer vehicle so it could piggy-back on a SpaceX rocket. While its proprietary rocket (which will launch the Orbiter directly) continues in development, the enhanced capabilities of their new AM system “made it very easy for us to pivot in the face of shifting priorities,” said Launcher’s head of manufacturing, Tim Berry.

    “That’s a benefit of additive technology in general, but especially when you’re using a highly-capable print platform,” he said. The company has now printed shrouded impellers, fuel tanks, brackets, combustion chambers, and injectors for various projects—and purchased additional AM equipment to use in-house.

  • Only his dorm room served as the R&D department for Ewan Craig, a 16-year-old British schoolboy who used his time during the pandemic lockdown to investigate the long-sought-after aerospike rocket, which engineers have been pursuing since the 1950s. With support from a software provider and an AM-system maker, Craig designed and had printed his own single-piece aerospike, which is now undergoing ground and eventual flight testing at a U.S. university.

    As AM technology continues to evolve, the most advanced systems are already delivering the level of quality that meets the highest standards demanded by aerospace and defense. The larger-capacity, taller 3D printers that are now being delivered will only expand the potential for innovative applications that can be explored—and delivered—by the industry’s OEMs, contract manufacturers, and energetic startups alike.

This article was written by Ben Wilson, Applications Engineer, Velo3D (Campbell, CA). For more information, go here .