Mechanical and technological aspects of micro ball end milling with various tool inclinations

Abstract

This paper is focused on the evaluation of mechanical and technological aspects of the micro ball end milling of hardened TOOLOX 44 steel. The experiment includes the measurement of acceleration of vibrations during the micro milling tests with variable feed per tooth and tool's axis inclination angle values. The next step involves the analysis of dynamics, based on the determination of measured signals’ statistical measures and Fast Fourier Transform (FFT). This stage includes also the prediction of micro ball end milling forces on the basis of mechanistic model considering run out, variable edge forces, and kinematics of low radial immersion milling with tool axis inclination. Subsequently, the optimization of the micro ball end milling process is conducted. This procedure is carried out by the minimization of process responses with the application of a method based on the minimization of total desirability function. In the last stage, the obtained optimal values of tool's axis inclination angle and feed per tooth are validated during the micro milling tests involving the measurements of machined surface roughness. Research reveals that micro ball end milling with the optimally selected tool's axis slope along the toolpath and feed per tooth affects the minimization of milling vibrations and improvement in surface finish.