Cutting force component in dry rough milling of AZ91D magnesium alloy using tools with different helix angles

Abstract The study investigates the normal to the feed force component of the total cutting force in dry rough end down-milling of AZ91D magnesium alloy. The overall goal of this work is to investigate the dependence of this cutting force component on the milling parameters (particularly high cutting speeds – high-speed milling). An interesting aspect of this study pertains to the impact of end mill geometry (e.g. different helix angles) on machining effects. The study also involves capturing and analyzing the component’s signal in the time domain first, and then assessing its dynamics in the frequency domain. In addition to that, the following are determined: maximum, peak-to-peak and root mean square values, along with composite multiscale entropy (CMSE) and outliers or extreme values in box plots. Also, an analysis is performed using recurrence plots, in order to assess the periodicity and continuity of the plot diagonals. Results show a clear relationship between the final CMSE value and the applied cutting speed and depth of cut. FFT analysis revealed that the signal recorded - particularly at high cutting speeds - is characterized by a significantly lower number of harmonics. The reduced complexity of the frequency spectrum indicates a potentially lower susceptibility to self-excited vibrations.