Modeling the machining stability of a vertical milling machine under the influence of the preloaded linear guide

The prediction of machining stability is of great importance for the design of a machine tool capable of high-precision and high-speed machining. The machining performance is determined by the frequency characteristics of the machine tool structure and the dynamics of the cutting process, and can be expressed in terms of a stability lobe diagram. The aim of this study is to develop a finite element model to evaluate the dynamic characteristics and machining stability of a vertical milling system. Rolling interfaces with a contact stiffness defined by Hertz theory were used to couple the linear components and the machine structures in the finite element model. Using the model, the vibration mode that had a dominant influence on the dynamic stiffness and the machining stability was determined. The results of the finite element simulations reveal that linear guides with different preloads greatly affect the dynamic behavior and milling stability of the vertical column spindle head system. These results were validated by performing vibration and machining tests. We conclude that the proposed model can be used to accurately evaluate the dynamic performance of machine tool systems designed with various configurations and with different linear rolling components.

► The main vibration modes of the spindle head system is dominated by linear guide modulus on feeding stock.
► The frequency increases by 18–37% as the preload of the linear guide is adjusted from Z0 to ZB.
► The dynamic stiffness increases by 1.5 times as the preload of the linear guide is adjusted from Z0 to ZB.
► The limiting axial depth with free chatter increases from 1.6 to 2.9 mm when the preload of the linear guide is adjusted from Z0 to ZB.