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Safran Aero Boosters and Sirris rethink turbojet engine blade production

Liège-based OEM Safran Aero Boosters wanted to assess whether it could produce its turbojet engine blades using additive manufacturing. At present, these metal parts – vital for aircraft propulsion – are made by conventional machining, with high levels of material waste. In 2014 and 2015, Sirris helped Safran Aero Boosters to assess the technology, by producing a series of parts at its own additive manufacturing facilities, and to select the most suitable equipment for the company’s needs.
  • Safran Aero Boosters wishes to use additive manufacturing to produce optimised blades, with less wastage.
  • In 2014 and 2015, Sirris produced blades (and a range of other parts) in order to confirm the feasibility of the project and select the most suitable technology.
  • Based on this, Safran Aero Boosters purchased a state-of-the-art machine in late 2015; Sirris is now helping with the technology transfer.
  • The project will continue as part of the Walloon Marshall Plan, with the aim of optimising the parts so that they can be qualified for use in aviation.

Liège-based company Safran Aero Boosters designs, develops and produces subassemblies, equipment and test stands for aircraft and rocket engines. As a partner to major engine-makers, its products are used on many of today’s commercial jet engines, as well as the Ariane launcher. 

“The chosen technology will enable Safran Aero Boosters to produce its parts more efficiently, as well as to optimise their shape, weight and strength.”

Hard-to-process titanium alloy 

The blades used in turbojet engines are made from a titanium alloy that is strong and light but hard to machine: up to 90% is lost as shavings when employing traditional techniques. Safran Aero Boosters asked Sirris to help it select a suitable additive manufacturing technology in order to produce optimised parts (lighter, stronger, more compact, etc.) that comply at least as well with aviation sector standards but with greater ease and less material wastage.

The solution: electron beam melting

With Sirris’s help, Safran Aero Boosters opted for an additive manufacturing technology called electron beam melting (EBM). This involves spreading a bed of metal power then building up the required shape layer by layer by melting the powder using an electron beam. Sirris used its EBM equipment to produce a series of blades and to demonstrate the feasibility of the project. In particular, the material wastage was very significantly reduced: the ‘buy to fly’ ratio (the ratio between the mass of material used to produce the part and the mass that actually ends up in the aircraft) fell from 10 to almost 1.

Next steps: optimisation and qualification

Based on the tests carried out by Sirris, Safran Aero Boosters ended its feasibility study with a positive conclusion and in late 2015 purchased a state-of-the-art machine. Sirris is now helping with the technology transfer. A new four-year Marshall project called Aero+ has got under way, in which a Walloon consortium comprising Safran Aero Boosters, Sirris, UCL, ULB, ULG, CRM, SAMTECH, AMOS and V2i will optimise the parts and validate them for use in the aviation sector.