Innovative manufacturing for greener aircraft engines
Aircraft engines could use fewer resources before they even leave the ground. EU-funded researchers have adapted cutting-edge manufacturing techniques to aircraft engine parts, cutting pollution and materials costs and making it easier to develop fuel-saving engine designs.
© 2016 Rolls-Royce plc
The MERLIN project has investigated how additive manufacturing could be used to produce and repair civil aircraft engine parts. Familiar from the concept of 3D printing, this method builds up parts, layer-by-layer, taking out the substantial materials waste, chemicals and tooling costs involved in traditional manufacturing methods for aircraft parts.
The EU-funded project developed processes that, as well as saving materials and costs, could make parts lighter and more robust – cutting their environmental impact. The manufacturing and repair techniques also support more extensive use of innovative materials. Project data is now being used to support international additive manufacturing standards.
Conventional aero engine manufacturing wastes large amounts of materials, many of which are toxic and carcinogenic. “An aeroplane engine typically weighs 7 tonnes but requires 28 tonnes of material to manufacture,” says acting project coordinator Carl Hauser of project partner TWI Limited. In contrast, additive manufacturing is low-waste, using almost all of the materials put into the process, but was rarely used in the aero engine parts industry when the MERLIN project started, he adds.
MERLIN investigated whether there is a commercial case for adapting two additive manufacturing techniques – laser metal deposition (LMD) and selective laser melting (SLM) – to the industry. LMD spools wire or powder into a melt pool generated by a scanning laser, while SLM melts powdered material together using a laser, in consecutive layers, to build up the part.
Savings and standards
Research on 14 demonstration engine parts – chosen for their diverse physical characteristics – showed that chemicals and finishing processes could be cut out from manufacturing and repairs. It also confirmed that LMD and SLM would also reduce materials waste and production costs. For example, when making parts using SLM, which leaves excess material, waste powder was recycled up to 14 times without affecting its quality.
In addition, the project developed techniques to improve applications of additive manufacturing and advanced materials. Achievements included a process for making parts with overhangs, a method for combining components made of materials that do not weld together easily, and NDT (non-destructive testing) systems for checking parts as they are made.
“We have improved understanding of how additive manufacturing impacts manufacturing with alloys,” says Hauser. “We can show that it is as good for some applications as traditional manufacturing.” He adds that the safety certification is the main barrier to using additive manufacturing for aircraft engines. “This project helps start the testing process.”
The demonstration parts were supplied by aero engine manufacturing companies for research in the project consortium, which also included research institutions and specialist SMEs. Other industries, such as oil and gas, are now interested in applying MERLIN’s results, says Hauser.
Non-commercial results have been published in open-source scientific journals and at conferences, with academic partners in the project continuing research on its results. A brochure demonstrating key outputs of the project is available on the MERLIN website.
Hauser says that he enjoyed MERLIN. “It worked well,” he says. “Everyone was very focused on working together on the various parts of the project.”