Multi-Criteria Assessment of Machining Processes for Turbine Disc Slotting

Many different process chains are possible to manufacture profiled grooves in turbine discs. Broaching with high speed steel tools is still state of the art today but as a consequence of the rising demand for aero engines, the disc manufacturers are striving for alternative high performance processes to increase both flexibility and productivity in the manufacturing of these safety critical features. Broaching machines are oftentimes at a bottleneck in the production of rotating turbine discs. Several other machining processes have been discussed in the context of slotting, such as broaching with carbide tools, milling, water jet machining, W-EDM and grinding. Within this paper a multi-criteria assessment approach is presented dealing with slotting processes. The assessment comprehends economical, ecological, flexibility and productivity criteria, and is based on data gathered with an aero engine OEM. The technological aspects such as tool life and productivities are based on real machining tests that have been carried out within the project HoFePro. The assessment is conducted for multiple profile shapes that represent different sizes and geometrical complexities of profiled grooves. The manufacturing processes within the assessment include broaching with HSS and carbide, milling with ceramics and carbide (side and end) as well as profile milling with carbide tools. The underlying workpiece material is a nickel-based alloy