EADS Innovation Works (IW), the aerospace and defense group's research and technology organisation, is always on the look-out for new manufacturing methods. A recent target for evaluation was an additive manufacturing process called Direct Metal Laser-Sintering (DMLS).
Developed by EOS, it is being used by EADS IW to manufacture demonstration parts to explore the benefits of optimised design and production sustainability. Protection of the environment is a key driver, while a reduction in the costs of manufacturing and operating its aerospace products also underlies the group’s research.
As quality, costs and environmental effects play a major role in the decision-making process for design and manufacturing solutions, EADS IW has defined new Technology Readiness Level (TRL) criteria focusing on sustainability. Nine TRL processes must be passed at EADS before a technology can be qualified for use in production. For each TRL review, a technology's level of maturity is evaluated in terms of performance, engineering, manufacturing, operational readiness, value and risk. For each of these criteria, new components must out-perform existing ones.
The results from the initial joint study of AM were evaluated in terms of CO2 emissions, energy and raw material efficiency and recycling. When analysing energy consumption, the company's investigation included not only the production phase, but also the sourcing and transportation of raw materials, argon consumption for the atomisation of the DMLS metal powder, and overall waste from atomisation.
An assessment by EADS IW highlighted, amongst other things, the potential cost and sustainability benefits of DMLS during the operational phase in the redesign of Airbus A320 nacelle hinge brackets. The data was backed up by test results from EOS and, in an additional step, by test results from a raw material (powder) supplier.
In the first instance, cast steel nacelle hinge brackets were compared to an additively manufactured (AM) bracket of optimised titanium design by measuring the energy consumption over the whole life cycle. The technology turned out to be a good fit for the design optimisation, as for this application the operational phase is typically 100 times more important than the static phases (e.g. manufacturing the part).
A comparison was made between manufacturing the optimised titanium component by rapid investment casting and on an EOS platform. Energy consumption for the life cycle of the bracket, including raw material manufacture, the production process and the end-of-life phase, is slightly smaller on the EOS platform compared with rapid investment casting. The main advantage of the EOS technology, however, is that the additive process uses only the amount of material for manufacture that is in the product itself. Thus consumption of raw material can be reduced by up to 75 per cent.
The study focused on the comparison between DMLS and rapid investment casting of a single part and did not take into account the question of scalability, which has yet to be addressed. However, some impressive results were documented.
The optimised design of the nacelle hinge bracket allowed EADS and EOS to demonstrate the potential to reduce the weight per aircraft by approximately 10 kg – a significant amount in aviation. CO2 emissions as a result of the brackets were reduced by almost 40 per cent over their life cycle by optimising the design, despite the fact that the EOS technology uses significantly more energy during manufacture.
Jon Meyer at EADS IW said, “DMLS has demonstrated a number of benefits, as it can support design optimisation and enable subsequent manufacture in low volume production.
"In general, the joint study revealed that DMLS has the potential to build light, sustainable parts with due regard to our company’s CO2 footprint.
"A key driver of the study was the integrated and transparent cooperation between customer and supplier, with an open approach that saw an unprecedented level of information sharing.
"The collaboration has set the standard for future studies involving the introduction and adoption of new technologies and processes.
"Even after the first positive results were evident, neither of the parties settled for the outcome, but continued to investigate options for further improvement.”
Part of the project's success was due to continued efforts towards further enhancements, evidenced by the swapping of the EOSINT M 270 DMLS machine for an EOSINT M 280 using titanium instead of steel, which led to additional CO2 savings. The technology has the potential to make future aircraft lighter, leading to savings in resources which help to meet sustainability goals, without compromising on safety.
Jon Meyer, ALM Research Team Leader at EADS IW, added, “We see several advantages in the use of DMLS, mainly concerning freedom of design and ecological aspects.
"We can optimise structures and integrate dedicated functionality, in addition to which DMLS can significantly reduce sites’ CO2 footprints, as our study with EOS demonstrated.
“Furthermore, considering ecology and design together, optimised structures can result in reduced CO2 emissions due to weight reduction. I see tremendous potential in DMLS technology for future aircraft generations, when it comes to both development and manufacturing.”