The influence of cutting edge microgeometry on the broaching of Inconel 718 slots

In aero-engine production, the dovetails (firtrees) of turbine discs are manufactured by broaching. Introducing innovative micro-geometry modifications to broaching tools can significantly influence cutting force, energy consumption, tool wear, and cutting edge temperature during broaching. Therefore, this study aims to study this influence by treating the cutting edge by brushing with ceramic bristles. The results reveal that the increase in cutting edge radius significantly influences the cutting force, particularly its component in the forward direction, equating it to the tangential component. Furthermore, during the experimental tests, considerable wear was observed on the cutting edge, which generated strong vibrations detected through the force signals, accounting to poor surface quality and a higher coefficient of friction close to 1. The 2D simulations generated information on temperature distribution along the cutting edge profile. On the other hand, was observed the presence of subsurface damage characterized by distorted grain boundaries aligned with the cutting direction, along with the formation of uninterrupted non-serrated chips due to thermoplastic deformation. Further, 12 µm cutting edge radius exhibits the best performance in terms of cutting force, temperature, and surface quality.