Force prediction model for five-axis flat end milling of free-form surface based on analytical CWE

As a high efficient machining technology, five-axis flat end milling is applied to free-form surface more widely. Cutter workpiece engagement (CWE) is an important issue for studying the milling mechanics. In this paper, milling force prediction model for five-axis flat end milling of free-form surface is presented based on a new analytical CWE model. Free-form surface is discretized into a series of tiny inclined plane. Three-axis flat end milling of inclined plane being study object, considering that the depth of cut is stacked by a series of thin cutting layers, the parametric formulas of CWE boundary curves can be obtained by calculating the intersection between cutter geometry and each thin cutting layer. The CWE of five-axis flat end milling of inclined plane can be transformed from three-axis flat end milling of inclined plane. The effective boundary points of in-cut cutting edge are derived by intersecting the analytical boundary curves of CWE with the parameter formula of cutting edge. Then combined with elemental cutting theory, this paper establishes force model of five-axis flat end milling of inclined plane as well as free-form surface. The experiments and simulations of CWE of five-axis milling show that the results of analytical method are in reasonable agreement with those of experiments and only a slight error with those of solid modeling method. Further, the influence rules of curvature radius of tool path on the accuracy of analytical CWE model are explored. Arranged milling experiments show that predicted milling forces are in reasonable agreement with measured forces in trend and amplitude, validating the effectiveness of force model for five-axis flat end milling of free-form surface.