Date of Award

Spring 2011

Project Type


Program or Major

Mechanical Engineering

Degree Name

Master of Science

First Advisor

Barry K Fussell


This thesis describes the effect of force model uncertainty on process planning. Specifically, the statistical variations in model predicted machining forces while cutting aluminum, carbon steel, stainless steel and titanium are determined. An accurate estimate of the variability is essential for use in process planning to determine appropriate factors of safety when setting cutting conditions that are both safe and efficient.

Force model coefficient calibration is described and the variability in the coefficients is determined through a least squares regression of a large number of experimental cuts. It is shown that the variability increases with changes in the calibration cutting conditions, e.g. radial depth of cut and spindle speed. Monte Carlo simulations of the cutting force are then used to determine the mean and standard deviation of the resultant peak force. A factor of safety is established for process planning using the mean plus three standard deviations. Statistically, 99.86% of the actual peak cutting forces should fall below the predicted value. The maximum expected peak force can be determined for each tool move in a NC program and used to select safe cutting conditions.