Shear-Zone Size, Compressive Stress, and Shear Strain in Metal-Cutting and Their Effects on Mean Shear-Flow Stress

A relationship for the calculation of the shear-zone size is given. The shear-zone size, when machining SAE 1015, 118-Bhn seamless steel tubing under a wide range of cutting conditions, is found to vary from 0.95 × 10⁻⁶ in.³ to 61.5 × 10⁻⁶ in.³ The mean shear-flow stress is found to increase significantly with a decrease in the shear-zone size and with an increase in the compressive stress in the shear zone. It is concluded that the only size effect in metal-cutting is the shear-zone size effect, and that no separate depth-of-cut size effect should be sought. An apparent decrease in the shear-flow stress with an increase in the true, mean shear strain in the shear zone is observed, and this behavior is explained.