Investigation of the cutting-edge radius size effect on dynamic forces in micro end milling of brass260

Abstract

Rapid increases in the number of industries that need a sub-micron surface finish on 3D micro/meso technological innovation parts are being seen. Due to the high rotating speeds of activities, chatter behaviour also occurs during micro-cutting. Changes in bearing stiffness, gyroscopic effects, and misalignment are only some of the factors that need to be considered while studying the spindle's dynamics. By regulating the movement of the cutting edge, the cutting action may be made more consistent. The structure of the tools also affects the machine's dynamics. Since the modes of different machine-tool components interact with one another, the dynamics of the tool tip are affected. In this research, we consider a model of a micro spindle system to enhance machining accuracy. Timoshenko beam theory is used to account for shear deformation and rotational inertia effects due to the short and thick beam-type designs of each component of the micro tool. A detailed dynamical model of the moving micro end mill is created using an extended form of Hamilton's Principle. A two-degree-of-freedom model of the micro-milling process considers the modal dynamic properties of the tool-holder-spindle assembly and the micro-milling cutting forces. A three-dimensional finite element model of the system is built, and its dynamic response is gathered, to validate the full order finite element approach. Cutting force coefficients are then modelled as a function of instantaneous uncut chip thickness, which is principally affected by the tool edge radius and feed per tooth at different radial immersion depths.