In the manufacture of engine parts, MTU Aero Engines says it has achieved a breakthrough – creating components for Pratt & Whitney PurePower production engines using a technique called selective laser melting (SLM). The parts are borescope bosses for the PW1100G-JM, which powers the A320neo.
“We are using one of the most advanced technologies there is to produce parts for one of the most advanced engines in the world, the geared turbofan,” proclaimed COO Dr. Rainer Martens.
The bosses form part of the turbine case and allow the blading to be inspected at specified intervals for wear and damage using a borescope. The SLM technique involves slicing up a 3D CAD model of the component to be produced. A laser then builds up the solid equivalent of the model layer by layer from a powdered material. Each layer is between 20 to 40 micrometres thick. The powder particles are then locally melted and fused together.
The bosses are only being produced in small quantities for now but volumes will grow significantly from 2015, as production of the PW1100G-JM ramps up.
MTU said it used to make the parts by casting or by milling them from the solid, but the benefits of additive manufacturing were “too compelling to ignore”. The manufacturer says the process allows complex components that are “extremely difficult, if not impossible” to manufacture using conventional methods to be produced with only small amounts of material and few tools. The technology also provides opportunities for entirely new designs; appreciably cuts development, production and lead times; and brings down production costs.
Dr. Karl-Heinz Dusel, senior manager, rapid technologies at MTU, said additive manufacturing was particularly suitable for producing parts in materials that are difficult to machine, such as nickel alloys.
Plans are afoot to redesign and produce further lightweight components, and Dusel expects additive manufacturing methods to enable easier production of complex components, “conceivably bearing housings and turbine airfoils”.