Optimal strategy for finishing impeller blades using 5-axis machining

This paper deals with the machining of impeller blades by defining a numerical method to optimize the finishing strategy. This method is based on the evaluation of new multi-physical functional indicators, which express the geometric and economical performances of a toolpath. Geometric indicators are defined to ensure functional requirements: aerodynamic, mechanical, and machining-related. Using these indicators, the viable impeller blade finishing strategies are compared, considering their geometric performances and production cost. The production cost is represented by machining time, which is accurately computed to limit blade and tool deflections, in order to reduce and control the geometric errors caused by these deflections. Machining time is directly linked to the feed rate, which is coupled to radial cutting forces. Thus, the finishing strategy is optimized by considering simultaneously a complete set of impeller machining problems: geometric errors and deflections. The method presented to optimize the blade finishing strategy is then applied to an industrial impeller used in a pump.