Methodical Evaluation of Process Chains for the Manufacturing of Rotating Engine Components – Profiled Slots in Turbine Discs

Abstract The aviation industry has ambitious goals to reduce the use of resources as well as emissions to achieve the pregiven targets defined in the Flightpath 2050. Therefore, a strong focus, beside developments of entirely new aviation engine concepts, is on advancements of current aircraft engine concepts allowing higher efficiencies during flight. Manufacturing is a key to enable adapted designs and to implement new materials. The production of safety-critical compressor and turbine discs for use in aircraft engines is mainly carried out in industrial series production using conventional manufacturing processes like milling, drilling and turning. In addition to the disc itself, profile grooves for form-fitting disc and blade connections are an important feature of engine discs. According to the state of the art, these are usually manufactured using the broaching process. Disadvantages of broaching are high tool wear (depending on the workpiece material), large, cost-intensive machine tools and long tool delivery times. In recent years, there has been a trend towards nickel-based alloys that are more difficult to machine, particularly in the turbine sector. In addition, the designs of the profile grooves have become increasingly challenging in terms of geometry and tolerance requirements. Alternatives to broaching are offered by unconventional manufacturing processes like Electro chemical machining (ECM), Electro discharge machining (EDM), Waterjet machining as well as milling. The productivity of these manufacturing technologies depends strongly on the rotor and specially slot design. The use of alternative manufacturing technologies must always be discussed against the background of the strength requirements of Class 1 components and the entire process chain including special processes. In addition to the already published paper GT2023-103706, in which a methodology for the evaluation of the different possible manufacturing process chains to produce the airfoil on Blisks/IBRs was addressed, this paper describes the extension of the methodology to the manufacturing of dovetail and firtree profile grooves in engine discs considering the process capabilities of the manufacturing technology as well as economic and ecologic boundary conditions. To have a basis for decisions which process chains are possible and which is most suitable the paper describes the approach of developing a modular evaluation methodology. The methodology considers the process capabilities of the manufacturing technology as well as economic and ecologic boundary conditions.