Surface integrity and economical assessment of alternative manufactured profiled grooves in a nickel-based alloy

The connection between turbine blades and the disc is realized via profiled grooves. For manufacturing these slots into the turbine disc out of hard to machine nickel-based alloys broaching with high speed (HSS) steel is still state of the art (SotA). Compared to other manufacturing processes this technology is less productive. However, alternative manufacturing processes like broaching with cemented carbide or wire electro discharge machining (WEDM) have to be qualified concerning the rim zone and existence of residual stresses as well as productivity and flexibility due to the high demands of the aero engines sector. In this paper, surface analyses of profiled grooves manufactured by cemented carbide broaching and WEDM are made. In carbide broaching a variation of the cutting speed and the effect of its increase on the rim zone are discussed. WEDM tests are performed with four trim cuts to evaluate the effects on the rim zone. All results are compared with the state of the art process. The completion of the investigations will be an economical assessment of the different manufacturing processes.