Aerospace 3D printing takes off

The aerospace industry moves from fast prototyping to additive manufacturing

By Peter Feuilherade

Demand for products made by 3D printing, also known as AM (additive manufacturing), is expanding in both consumer and industrial markets as the technology, which has been around since the 1980s, becomes more widespread. The adoption of high-end AM in the aerospace sector has already led to innovation in that industry.

This 3D-printed high-temperature fuel nozzle is 25% lighter, 5 times more durable, runs cooler than current nozzles made from 20 different parts (Photo: GE) This 3D-printed high-temperature fuel nozzle is 25% lighter, 5 times more durable, runs cooler than current nozzles made from 20 different parts (Photo: GE)

Fast-growing sector

The AM global market grew by about 35% in 2013 to reach more than USD 3 billion, the highest annual growth rate in 17 years, according to Wohlers Associates, a 3D printing consulting company based in Colorado, US. The market is currently dominated by a handful of companies that own the core technologies.

The US currently has a 38% market share of the total worldwide AM industry, followed by Japan with 9,7%, Germany (9,4%), China (8,7%), the United Kingdom (4,2%), Italy (3,8%), France (3,2%) and South Korea (2,3%).

US based consultants Allied Market Research forecast in mid-2014 that the overall global 3D printing market could reach USD 8,6 billion by 2020, registering a CAGR (Compound Annual Growth Rate) of 20,6% from 2014 to 2020. Although products made for the consumer market will dominate demand, metals and alloys are projected to be the fastest growing materials segment, forecast to grow at a CAGR of 40,5% during 2014-2020.

Wohlers reported growth of almost 76% in the metal 3D printing sector in 2013, based on the number of metal-based AM machines sold worldwide.

Hi-tech sectors to drive high-end 3D printing systems

Aerospace, along with healthcare, is one of the sectors leading the adoption of 3D printing processes, starting with non-critical parts because of stringent safety testing rules. In 2012, the aerospace and defence industry accounted for about 10,2% of additive manufacturing's total global revenues of USD 2,2 billion.

A growing number of leading manufacturers of airframes, engines and components, among them Boeing, GE (General Electric) Aviation, Lockheed Martin, Airbus and BAE Systems, are now using AM to produce complex aircraft and spacecraft parts not only from plastic but also metal. GE, which is already the world's largest user of 3D printing technologies in metals, expects to have manufactured 100 000 cobalt chrome fuel nozzles for jet engines using 3D printing by 2020.

The US, the largest aerospace manufacturer in the world, is also at the forefront of AM technology, with the UK not far behind. Investment is being driven by big corporations as well as governments. In July 2014, GE Aviation announced plans to invest USD 50 million in its own AM plant in Alabama. In January 2013, US jet engine manufacturer Pratt & Whitney announced that it would invest USD 9 million over 5 years in developing powder-based AM technologies to further refine electron beam melting and "laser powder bed" AM. The UK government has allocated GBP 49 million (USD 81 million) to fund research on 3D printed aerospace technology.

Saving time and materials

The most successful AM processes currently being used to make metal products of various shapes include direct metal laser sintering, developed by the German company Eos, and the Swedish firm Arcam's electron beam melting process. Both are powder based processes that make components from metal powders by building up layers of titanium or other raw materials using computer-driven machines.

The advantages for aerospace firms include time savings, reduced waste and design flexibility.

Using computer-generated design models, AM uses lower quantities of raw materials than do subtractive production methods, produces negligible levels of waste and allows precision engineered replacement parts to be printed in situ in a matter of hours. This gives it the potential to replace traditional forging, casting and machining processes.

"The technology is expected to have far-reaching consequences for the aerospace industry… and especially the maintenance, repair and overhaul business, because it reduces the time and effort needed to produce parts or find spare parts", Reuters news agency reported from the Farnborough International Airshow in July 2014.

Market projections for the aerospace 3D printing sector vary considerably. While Portuguese investment bank Espirito Santo conservatively sees the market tripling to just short of USD 700 million between 2012 and 2016, Credit Suisse forecasts CAGR of 30% up to 2016, with aircraft engines leading the way. "This implies an addressable market for printing systems for aircraft engines of approximately USD 1,4 billion in 2016. This represents over six times the entire 3D market for aerospace today, which is not limited to only aircraft engines, and includes sales of materials, service, software and parts", Credit Suisse adds.

Ensuring safety and quality

Ensuring safety and product quality are critical considerations when using 3D printing to produce components for aircraft and spacecraft. It is vital that parts in aircraft engines and bodies can resist corrosion and vibration and are free from defects that could leave them prone to mechanical or heat induced stress.

Selective laser melting technology, for instance, produces parts that can contain microscopic voids within the structure of the material and are prone to heat-induced stress, so these components cannot be used in critical load-bearing applications. Electron beam technology, however, is a higher quality alternative to laser melting and able to produce components free from residual stress.

Product quality and cost are also major considerations. So far, 3D printing has been used primarily for manufacturing prototypes and demonstration specimens, but that is changing, as GE's commitment to the large-scale production of fuel nozzles demonstrates.

The costs of 3D printing machines and the metal powders that they use are expected to decrease as the technology improves and becomes more widely used for mass production rather than specialist applications only. But the speed of 3D production would also have to increase and outpace conventional manufacturing methods to make it feasible for large scale adoption of 3D printing by aerospace companies in producing the more common parts and components.

The additive manufacturing presence in the aerospace industry is extremely low, at 0,002% of a market totalling USD 150 billion, according to Vivek Saxena, vice-president of aerospace operations and supply chain at the US consulting firm ICF.

For the time being, 3D printing is an additional process that is best used for manufacturing certain parts used in the aerospace industry; it has not yet replaced traditional manufacturing. Most components still require costly finishing work after the additive manufacturing process.

Although the use of 3D printing in aerospace factories is certain to spread, the extent of this growth is uncertain at present, which reflects the embryonic stage of AM development. Because regulatory approval is "the biggest issue right now", the quickest adoption of 3D printing is likely to be in applications that face the least regulatory scrutiny, such as UAVs (unmanned aerial vehicles) and experimental aircraft, Saxena predicts.

Researchers at global defence firm BAE Systems are studying the feasibility of equipping military aircraft with on board 3D printers to create different types of UAVs on demand, depending on the mission objective.

Space – the next frontier

Space-based 3D printing also offers future opportunities. Both NASA (National Aeronautics and Space Administration) and the European Space Agency are looking at 3D printing for products ranging from rocket engine components to food that astronauts could prepare in deep space. But given the numerous environmental factors that affect 3D printing, including zero gravity and extreme temperature fluctuations, these projects are still largely ground based.

A July 2014 report by the US National Research Council concluded that while AM could contribute positively to space operations, the specific benefits and potential scope of the technology's use in space remain undetermined, and "its application in space is not feasible today, except for very limited and experimental purposes".

IEC sets Standards for quality, safety

A number of IEC TCs (Technical Committees) and SCs (Subcommittees) work on identifying, developing and coordinating International Standards for the electric and electronic components that are installed in the 3D printers being used in additive manufacturing processes.

Amongst many other relevant parts and components are switches and relays (TC 17: Switchgear and controlgear, TC 121: Switchgear and controlgear and their assemblies for low voltage, and their SCs), servo and stepper motors used to move the extrusion head or the sintering laser (TC 2: Rotating machinery) are power supplies (TC 96: Transformers, reactors, power supply units, and combinations thereof). Most important are the different types of lasers used for sintering metals and polymers.

TC 76: Optical radiation safety and laser equipment, is the leading body on laser standardization, including the high-power lasers used in industrial and research applications. Its work will be essential to the future of 3D printing in the aerospace sector as, increasingly, parts for the industry will be produced using metal powders that require laser technology for their manufacture.

This 3D-printed high-temperature fuel nozzle is 25% lighter, 5 times more durable, runs cooler than current nozzles made from 20 different parts (Photo: GE) This 3D-printed high-temperature fuel nozzle is 25% lighter, 5 times more durable, runs cooler than current nozzles made from 20 different parts (Photo: GE)
AM metal hinge for aircraft engine covers (fore): 50 % lighter than the conventional model (back) (EADS) AM metal hinge for aircraft engine covers (fore): 50 % lighter than the conventional model (back) (EADS)
Rolls Royce introduces 3D printing to make parts for its next jet engines (Photo: © 2010 Rolls-Royce plc) Rolls Royce introduces 3D printing to make parts for its next jet engines (Photo: © 2010 Rolls-Royce plc)