Time Domain Analysis of Machining Stability in Hemp Board Milling

Chatter vibrations in cutting are uncontrolled (self-excited) vibrations in a machine–tool–workpiece system, occurring without the involvement of external forces. They result in accelerated tool wear and reduced surface quality. One way to avoid self-excited vibrations is to optimize cutting parameters based on stability analysis results. This can be achieved by using a numerical simulation method for self-excited vibrations in the time domain. This article compares the numerical simulation results with experimental results from milling hemp boards using a 2-flute uncoated HSS-E milling cutter. The fundamentals of milling process stability analysis for an actual mass–dissipation–elastic system are also presented. Experimental studies were conducted within a variable range of cutting speed (18–63 m/min) and axial depth of cut (up to 8 mm). As cutting conditions changed from stable to unstable, an over three-fold increase in the average roughness Sa value and an over two-fold increase in the maximum height Sz value were observed. The results confirmed that numerical simulation, despite the increased computational cost, is more accurate than analytical methods for calculating the stability limits of milling parameters. The average difference between the experimental and numerical simulation stability limits was 0.18 mm, resulting in a mean discrepancy of 6%.