FORCE ANALYSIS OF ORTHOGONAL CUTTING OF BOVINE CORTICAL BONE

In orthopedic operations, no sound solutions exist to avoid conditions like tool breakage, bone fracture/cracks and thermal necrosis for lacking understanding of the mechanics of the bone cutting process. In this work, analysis of variance (ANOVA) and regression analysis were performed to investigate effects of cutting conditions on cutting and thrust forces based on a full factorial design. Then applicability of Merchant's analysis for calculating cutting force with respect to rake angle and feed was evaluated by comparison with experiments. Finally, the friction coefficient was evaluated by calculation. ANOVA shows that forces are much more sensitive to feed, cutting direction and rake angle than to cutting speed. Regression equations including all four factors were obtained by introduction of dummy variables. Cutting forces from experiments and from Merchant's analysis are partially comparable (maximum relative error=34%) when feed and rake angle are changed. Friction coefficient was affected by rake angle and cutting direction. Cutting speed had little effect on the coefficient. These results can deepen the understanding of the mechanics of the bone-cutting process and assist the development of innovative cutting devices and selection of favorable cutting conditions for the procedure.