In-Process Compensation for Milling Cutter Runout via Chip Load Manipulation

This paper discusses a real-time chip load compensation methodology for the elimination of cutting force oscillation and machined surface scalloping due to cutter runout so as to gain better utilization of machine tools. The concept and implementation of the methodology is illustrated using end milling as a process of example. In this work a force feedback system was discussed in the angle domain based upon a proportional-integral control strategy and a repetitive learning control strategy to actively manipulate the chip load during end milling. Numerical simulations based on experimentally identified machining dynamics were presented to compare the performance of the two control schemes. Experimental investigation under various cutting conditions was performed to assess the viability of the feedback compensation system in the context of cutting force response as well as machined surface finish. It has been shown that a proportional-integral control has limited effectiveness in eliminating the runout-induced cutting force oscillation due to the constraints of system stability and dynamic performance. On the other hand, the learning control system based on the internal model principal successfully yields a cutting force free of oscillatory components at the spindle frequency and significantly improves the quality of machined surfaces by cancelling the nonasymptotically stable dynamics of cutter runout.