On the analysis of cutting mechanics in orthogonal cutting, each cutting force component can be predicted. By adding the flank face wear term to the prediction equation for cutting force components, complete equations are obtained. Using these equations, it is shown that cutting force components are increased linearly as flank face wear land is developed, in theory and experiment. By making non-dimensional term ie. Fv/Fc, the width of variation of output signal Fv/Fc is greately decreased compared with each cutting force component as cutting condition is varied. Among these conditions, the variation of chip width in the range of more than 1mm and that of cutting velocity have little effect on the output signal Fv/Fc, that of Flank face werr land can be detected without difficulty.