Analyzing the Effect of Workpiece Stiffness Variation on the Stability in Flank Milling of an Impeller Blade

While the blade like components of uniform thickness have been investigated for their stability in machining, impeller blade like components with varying thickness along the length and with varying width along the height have received little attention so far. Therefore, this work focuses on analyzing the effect of variation in workpiece flexibility, stiffness and rigidity on the stability of flank milling operation on impeller blade like component. Extensive experimentation was done on work specimens of (i) varying thickness along length and (ii) varying width along height. Cutting forces, acceleration and deflection of tool and work specimens were captured during all the experiments through FFT plots, chatter boundary plots followed by the stability region diagrams. The cutting force data was acquired in time domain at five different locations under varying conditions of spindle speeds and depths of cut, and were the main inputs for plotting stability region diagram. The consolidated stability region diagram shows that the stable machining, baring the few chatter peaks of low frequency and magnitude, is possible at the feed rate of 240 mm/min. and depth of cut of 1.5 mm, when the thickness as well as the width variations in the impeller blade like specimens are considered.