3D printing: increasingly key to aviation

Additive layer manufacturing or 3D printing is now widely used in aerospace – even making the journey to another planet. Mark Broadbent reports

Additive layer manufacturing (ALM), also known as 3D printing, has been part of the aerospace industry since the 1990s, but only in the last decade has it moved from being a niche technology mostly found in R&D work to become part of the sector’s technological mainstream.

H Goussé/Airbus
CFM International produces 3D-printed nozzles for LEAP engines
H Goussé/Airbus

Chris Schuppe, general manager of engineering and technology at GE Additive, told AIR International: “The aerospace sector was an early adopter of metal additive technology and continues to be a super-user. We see no sign of that slowing down. The pace and deployment of additive at an industrial scale, especially in the US and across Europe, demonstrates that additive is a viable manufacturing technology that can differentiate products while still meeting the cost and quality targets expected from aerospace products.”

What is 3D printing?
ALM involves depositing plastic, aluminium, titanium or steel powder into a template in successive layers. Lasers bond each layer until a 3D shape ‘grows’ into the desired structure.

The technique offers numerous advantages over traditional manufacturing. Forging, moulding and cutting of parts is not required, which reduces excess material and wastage. Lighter parts mean lower fuel consumption and a fall in CO2 emissions. And manufacturers can tightly control the finished shape of a part to produce highly optimised designs. As Munich-based 3D printing specialist EOS points out, this enables “maximum functionality to be integrated into as few parts as possible.”

Other benefits are the absence of complex and expensive heavy machinery/tooling, quicker implementation of product adaptations and the repeatability needed for volume production – all of which creates further cost and time savings.

ALM’s value goes beyond new products, a spokesperson from GKN Aerospace, another provider of ALM products, told AIR International: “ALM is widely and increasingly used for tooling in the production of aircraft components because of short lead times, relatively low cost and the potential of rapid improvement cycles increasing the efficiency on the factory floor.”

VK-1600V engine
All of these benefits mean that additively manufactured parts have become commonplace across aerospace, from fixed-wing aircraft and helicopters to engines and satellites.

One new application announced recently is the United Engine Corporation (UEC) VK-1600V unit that will power the Kamov Ka-62 helicopter. A laser printer at UEC parent company Rostec’s Additive Technologies Centre in Moscow will produce up to 70% of the VK-1600V’s casting and parts of the stator in the ‘hot’ part of the engine. Along with other ALM-produced components in the airframe, around 10% of the Ka-62 will be 3D printed, UEC said.

Rostec executive director Oleg Yevtushenko commented: “Additive technologies will reduce the production time for individual components from six months to three weeks.”

CFM, GE Aviation, Rolls-Royce
CFM International produces 3D-printed nozzles for the LEAP turbofans on the Airbus A220 and A320neo, Boeing 737 MAX and COMAC C919 airliners. GE Aviation, the 50/50 co-owner of CFM with Safran, also produces more than 290 metal 3D-printed parts for the GE9X turbofan that powers the Boeing 777X, including the aircraft’s low pressure turbine blades and fuel nozzles.

Trent XWB
The engine front bearing housing that Rolls-Royce developed for the Trent XWB-97 Rolls-Royce

Nearly 30% of the components in GE’s new Catalyst turboprop engine are 3D printed. GE Additive’s innovation leader, Josh Mook, told AIR International that these parts “reduce the Catalyst’s weight by 5%, while contributing a 1% improvement in specific fuel consumption and up to 20% better fuel efficiency than legacy turboprop engines available today.”

Rolls-Royce has put an additively manufactured combustor into the Pearl 10X engine it has developed for Dassault’s recently launched Falcon 10X bizjet.

The company previously produced a titanium front bearing housing for the Trent XWB-97 that was flight-tested in 2015 on the Airbus A380. That part did not enter production in the end, but Rolls-Royce explored 3D-printed technologies on its Advance3 technology demonstrator which itself fed into the next-generation UltraFan engine that will run for the first time in 2022.

From airliners to fighters
The Airbus A350 has more than 1,000 3D-printed components and there are additively manufactured parts in the A330neo cabin’s climate control system. A back-up fitting for an access door latch in the forward fuselage of the Boeing 787 is made from 3D-printed structural titanium supplied by Norsk Titanium.

MTU Aero Engines uses EOS-supplied 3D printing machines to build borescope bosses for the Pratt & Whitney PurePower PW1100G-JMs, while Liebherr used EOS equipment to produce the A380 primary flight controls.

Stratasys 3D printers are used by the Adlington, Cheshire-based company Senior Aerospace BWT, which manufactures ultra-lightweight, low-pressure air distribution systems for aircraft and helicopters.

There are additively manufactured parts on the Lockheed Martin F-35 Lightning II and Boeing F/A-18 Super Hornet. In 2019, the US Air Force introduced a 3D-printed bracket in the F-22 Raptor’s cockpit assembly to replace a corrosion-prone aluminium component.

BAE Systems uses four industrial-grade Stratasys F900 3D printers at its Salmesbury site to manufacture Typhoon subassemblies and parts, as well as undertake design verification on prototypes and produce manufacturing tools. BAE uses additive manufacturing at its Factory of the Future at Warton, opened in 2020, and has long-termplans to 3D-print up to 30% of the Tempest fighter.

A 2020 BAE Systems statement said additive technology means “you can design impossible structures (like cavities inside solid blocks, for example) that you wouldn’t be able to machine otherwise.”

Satellites and Mars rovers
In spaceflight, additively manufactured components include oxidiser valves in the SpaceX Falcon 9 rocket’s Merlin 1D engines and the SuperDraco engines in the Crew Dragon spacecraft’s launch escape system, as well as turbines supplied by GKN to ArianeGroup for the Prometheus engine on the Ariane 6.

Airbus
Painting a 3D-printed spacer panel Airbus

United Launch Alliance’s Atlas V rocket has Stratasys 3D-printed components in its environmental control system ducting. ALM is used on satellites by both Airbus Defence and Space and Lockheed Martin – the latter is even planning to produce a satellite produced entirely using 3D printing.

Airbus Defence and Space UK in Portsmouth produced more than 500 3D-printed radio frequency components for the two Eurostar Neo-series satellites, HOTBIRD 13F and 13G, that will be launched later in 2021 to support Eutelsat’s TV relay services over Europe, the Middle East, and North Africa.

Additively manufactured parts have even made it to Mars. NASA’s Perseverance rover on the red planet has 11 3D-printed metallic components in two instruments. Its Curiosity predecessor had a 3D-printed part inside a sampler.

Doing things differently
GE Additive’s Josh Mook told AIR International that 3D printing offers potential for “reimagining conventionally manufactured parts”, adding that the company is “increasingly working on the next generation of engines, which incorporate additive technology at the conceptual stage.”

Chris Schuppe observed that some companies are also working with GE Additive on “the total value chain of producing their parts additively, not just the 3D printing itself.”

He said: “Build file set-up, distortion and compensation modelling, scan path optimisation, powder loading and unloading, recycling powder, post-processing and inspection, qualification and certification are just some examples where they are asking us for help.

“Other customers are looking for dedicated service support or more autonomous servicing of their additive manufacturing machines on their own. Many of those who are just getting started with the technology are looking for help in identifying the right applications and designing them for the best business case outcome.”

Future challenges
Mook cautioned that the path to serial additive production should be regarded as “a marathon, not a sprint.” He reflected that although some users initially exhibit “early exuberance and are excited to dive in” to using metal additive technologies, there are sometimes “production issues such as build stops, build failures, machine-to-machine variations and build variations.

Airbus
Airbus’ HOTBIRD 13F satellite features 3D-printed components made in Portsmouth Airbus

“[However] like any relatively new technology, it takes time for the familiarity and understanding to reach critical mass. The more people who become proficient in additive, and in how and where it can be most successfully deployed, then the quicker production applications will grow.”

COVID-19 impact
Chris Mook believes that continued education is required to encourage change in engineering, supply chains and business decision makers.

A GKN spokesperson commented: “With the increased awareness and knowledge of ALM globally, new products will arise that we could not imagine using conventional technologies. There will be more niche applications where ALM will be the prime solution. The main technology developments will be to get the part cost down and [make] the equipment more reliable, enabling more applications to be feasible.”

Might the spirit of innovation in the industry post-COVID-19, evident in the seemingly greater interest in ‘green aviation’ developments and digitalisation, encourage more enthusiasm for ALM?

Schuppe said: “We noticed that the conversation changed during COVID-19 – not just in the aerospace industry but across all industries. Many companies have used this event to fundamentally rethink their product, environmental and supply chain strategies. Part of this is incorporating advanced manufacturing technologies, not just additive, but software and AI as well.”