Robust Stability of Machining Operations in Case of Uncertain Frequency Response Functions

Prediction of machine tool chatter requires a dynamic characterization of the machine-tool-workpiece system by means of frequency response functions (FRFs). Stability lobe diagrams are sensitive to the uncertainties of the measured FRF, which reduces the reliability of their industrial application. In this paper, a frequency-domain method is presented to determine robust stability boundaries with respect to the uncertainties of the FRF. The method is based on an envelope fitting around the measured FRFs combined with some considerations of the single-frequency method. The application of the method is validated on a turning operation characterized by a series of FRF measurements. It is shown that stability analysis using the averaged FRF may considerably overestimate the region of robust stability.