Accurate process modeling requires the calculation of cutter/workpiece engagement (CWE) geometry. This is challenging when the geometry of the workpiece is changing un-predictably as is the case for most machined components of moderate complexity. Solid modelers are increasingly being considered as a computational engine for performing these calculations. This is largely due to increased robustness and computing efficiency that is evolving within this technology. The vast majority of reported research using solid modelers focuses on the domain of 2 1/2 D machining with flat end mills. While significant there remain restrictions in the types of inprocess workpiece geometry that can be processed with these approaches. In particular, they assume a constant axial engagement for a connected set of tool paths. This assumption cannot be made when the initial workpiece geometry is non-rectangular prismatic stock, when multiple setups are machined and when tool changes introduce tools of different diameters. In these cases the depth of engagement can vary over a single rotation of the cutter even though there is no axial feed motion. In this paper a solid modeling based solution is presented for calculating these engagements when multiple setups and tool changes are considered. Orthogonal setups and flat end mills are assumed so as to preclude cutter engagement on inclined workpiece faces. Classes of Cutter Engagement Features (ceFs) are defined to support this approach. Algorithms for ceF extraction are provided and validated using a test part. This research introduces the use of features and extends the capabilities of solid modeling techniques for cutting force prediction.

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