Development of process monitoring strategies in broaching of nickel-based alloys

Due to their stability under high mechanical and thermal loads nickel-based alloys generate high cutting forces and temperatures during machining which adversely affect tool life. Especially in broaching with form shaped tools, deviations from the original tool geometry cause an inacceptable product quality. In aero engine industry, where quality standards for machining of safety critical parts are very high, this cannot be tolerated. Because of its tool geometry broaching is different from other machining processes: due to the high ratio between cutting edge radius and chipping thickness, the influence of the tool wear at the cutting edge is strong, especially for the finishing section. In order to guarantee stable machining processes in production, monitoring methods are desired that are capable to recognize changes in cutting conditions. The EU funded ACCENT project focuses on this challenge: the goal is to use process monitoring to make conclusions about the product quality during machining and, if necessary make adjustments to process input parameters to keep the quality measures in a defined window.