Force and stability modeling for non-standard edge geometry endmills

This paper describes a reverse engineering solution for modeling the behavior of nonstandard edge geometry endmills. Structured light scanning is used to produce a solid model of the endmill and spatial coordinates for the points that define the cutting edges that are extracted. These points are then used to determine the cutting edge radius and angle at equally spaced points along the tool's axis. This cutting edge geometry is applied directly in a time domain simulation that predicts the cutting force and tool/workpiece deflection for user-selected operating parameters. A good agreement between predicted and measured cutting forces is first demonstrated for two non-standard edge geometry endmills. Second, the results of stability tests are compared with simulation predictions for multiple spindle speed-axial depth of cut combinations using one of the endmills. The time records are analyzed by periodically sampling the measured and predicted displacement and velocity. Third, the time domain simulation is used to generate a stability map that separately identifies stable (forced vibration) behavior, secondary Hopf bifurcations, and period-n bifurcations.