Facing a high demand for aircraft engines over the next decades in combination with new challenging materials, aircraft engine manufacturers are striving for new manufacturing processes. The manufacturing of profiled grooves for the mounting of the turbine blades on the disc is a bottle neck process today due to the exclusive use of High Speed Steel (HSS) tools in broaching. Because of the limited hot hardness of HSS, the applied cutting speeds are low compared to other conventional machining processes, i.e. 2–5 m/min. Furthermore, the broaching process has some more drawbacks regarding flexibility, capital commitment for machinery and tools as well as costs. Nevertheless, broaching offers outstanding properties regarding surface finish, manufacturing accuracy and is still a productive process due to the many cutting edges applied. There are some alternative process chains which are not yet in industrial use, which are able to substitute and/or complement the HSS-broaching process.

In this paper, results are presented on two different roughing strategies for the manufacturing of profiled grooves in Nickel Based Alloys Allvac718plus and Inconel718. On the one hand, rough broaching with cemented carbide tools using indexable inserts was investigated at different cutting speeds, which are up to five times higher than the applied cutting speeds in industrial applications with HSS-tools. Two different carbide grades were investigated varying the cobalt content and the grain size. Cemented carbide is not state of the art in broaching Nickel Based Alloys due to its low fracture toughness. Different cutting edge inclination angles were applied and their effect on cutting forces, wear and tool chipping tendency were analyzed. On the other hand, rough side milling with ceramic cutting tools was investigated. Ceramic cutting tools excel in high hot hardness and thus can be used at very high cutting speeds i.e. up to 1000 m/min in Nickel Based Alloys. However, being very brittle and sensitive to alternating loads and thermal shock, machining processes with ceramic tools require extensive process design. In side milling experiments, Whisker reinforced as well as SiAlON and Oxide ceramic were investigated. In a first step, a window for machining parameters was identified. Then, tool life tests were conducted varying the feed at a fixed cutting speed of 1000 m/min. Subsequent to the experiments, the rim zone of the roughed grooves was investigated depending on the wear state of the used tools. The condition of the rim zone is a major criterion for the assessment of the adequacy of the roughing processes, because it can affect the subsequent finishing process. In further work, the interdependencies between the investigated roughing processes and finishing will be addressed.

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