Investigation of the cutting force coefficients in ball-end milling

This paper investigates the cutting force coefficients embodied in the cutting force model of ball-end milling. A series of slot milling tests was performed with a one-tooth helical ball-end mill for the calibration of the cutting force coefficients. The recorded dynamic cutting forces are averaged to fit the theoretical model and yield the force coefficients. The reasonable agreement between the measured and simulated dynamic cutting forces demonstrates the effectiveness of the calibration method. The results are compared with those obtained from a series of slot milling tests using a one-tooth helical end mill under similar cutting conditions. The two sets of coefficients, especially the axial force ratios, differ from each other significantly. In a further investigation of the coefficients, another series of cutting tests including plane milling, down-hill and up-hill slope milling with a two-edge helical ball-end mill was undertaken, and the results obtained indicate that the axial force ratio is greater when the engaged part of the cutting edge moves away from the tip point of the cutter, and it approaches zero as the contact part moves closer to the tip point.