CFM International (H4/B13, chalet A23-24) will produce parts for the Leap-X family of engines for narrowbody aircraft based on an additive manufacturing process developed at GE's Global Research Center and inspired by three-dimensional printers.
While 3D printers build objects by adding multiple layers of polymers, the Leap parts will be built by layering and "consolidating" metal powder using a laser welding machine.
"Instead of subtracting material with machining, you bring the part up one layer at a time," says Prabhjot Singh, manager of the additive manufacturing lab at the Global Research Center. "It's most suitable when you have a complex design with a large number of steps or a material that is hard to process. Geometry has almost no bearing on the manufacturing capability."
GE is a 50:50 partner with Snecma in the CFM engines business, with GE focusing on the high-pressure, or core section of the engine and Snecma responsible for the low-pressure and fan sections. GE has been developing the additive manufacturing technology for 20 years, says Singh, and is already using the method on some parts repair work for engines.
While CFM did not state which additive manufactured parts will be present on the Leap engine, Singh discussed the advantages of the technology using brackets as an example. "With additive, you can make the shape much more complex," he says. "It's functionally equivalent, but a lot lighter in weight, which corresponds to fuel savings." He says the additive manufacturing can also be used to build "certain types" of heat sensitive parts, adding that he is working on "some really interesting parts".
Singh says the technology, which can result in parts that weigh half as much as traditional milled or hogged-out components, dramatically increases the buy-to-fly ratio - the amount of material you buy versus how much makes it into the product. "That's important for expensive alloys," he says.
Parts are typically built starting with a computer-generated model of the part, which is "sliced up into thin cross sections", says Singh. In his laboratory, Singh has a SLM Solutions laser micro welding machine that can build parts in a volume of 25cm (10in) by 25cm by 30cm. Metal is spread in layers that are 20-30 microns thick, after which a 200W laser "draws" the outline and the process is repeated. The machine can assemble a 3D part at a rate of about 2.54cm per 24h.