Modelling and Optimization of Bone-Cutting Forces in Orthopaedic Surgery

Orthogonal cutting data is extremely useful since the measured force relationships can be used to model almost any machining process. However, previous orthogonal cutting investigations in bone have not tested conditions representative of clinical operations (i.e. very high tool speeds and small depths of cut, as in high-speed milling). In this paper, we aim to build a cutting force model that will be applied to the design, modeling, and optimization of a new robot-assisted high-speed milling system. Experimental results are presented for the cutting force components and the specific cutting energy of bovine cortical bone as a function of cutting tool geometry, depth of cut, and relative orientation between the cutting edge and bone structure. The cutting force magnitudes and trends prove to be considerably different from those previously reported in low-speed experiments, confirming the strong dependence of machining forces on cutting speed.