Chatter Stability Prediction in Low Immersion Milling Based on Time-domain Simulation

Abstract

Chatter is a major limitation in the machining process, which affects the machined surface and productivity. An accurate stability lobes diagram is efficient to avoid chatter. A small radial depth of cut often used in finish milling means a small uncut chip thickness and highly interrupted machining process. The tool is easy to jump out from the workpiece, which causes obvious non-linearity. Hence, the common circular tooth path is improper to approximate the true tooth path, and influences the accuracy of the stability lobes diagram. A time domain simulation approach based on a dynamic chip thickness model to predict chatter stability in end milling is presented. The time domain simulation for the dynamic cutting process in end milling takes into account both the tool and workpiece dynamics and uses a true tooth trajectory for evaluation of the chip thickness. The variation in the correlation coefficient of the vibration signals between two concessive tool revolutions is examined for developing chatter criterion. The proposed method is assessed and verified using experimental data in low immersion milling of titanium alloy Ti6Al4V. The proposed approach provides a useful way for industrial planners to select chatter free cutting conditions in end milling.