Influences of workpiece stiffness on high speed milling stabilty

High-speed milling (HSM) of thin-walled workpiece is widely used in the manufacturing of airframe components. The prediction of stable milling region plays an important role in the machining process. However, the prediction of its stable milling faces more difficulties because HSM is characterized with time-varying, nonlinear, multi-field coupling. In this paper, a dynamics model of HSM system is set up considering time-varying workpiece stiffness due to high material removal rate. A method is proposed by transforming time-varying stiffness system into fixed-step time invariant one. A thin-wall workpiece experiment is setup, and the dynamic characteristics and chatter stability of high speed milling are predicted and the influence of that on system stability is analyzed. Then the stability lobes diagram (SLD) is elaborated and a 3D SLD considering the stiffness as the third coordinate is proposed. The results show that, variational workpiece stiffness during the milling process has non-ignorable impact on the stability limitation, which must be considered for predicting stability limit in the high speed milling.