Determination of stress state in chip formation zone when orthogonal machining nickel-based superalloy Inconel 718

Abstract

An analytical force model with shearing and ploughing mechanisms is established for orthogonal machining of nickel-based superalloy Inconel-718. The force balance is conducted on the main boundary of the deformation zone, leading to the machining force model. These machining force components are distinct functions of the shear angle and tool edge radius. Increasing the tool edge radius will influence the average rake angle and lead to the increment of chip formation and ploughing forces. Using the machining force model in calculating shear stress on the main boundary of the deformation zone will demonstrate the influence of the size effect when using edge radius tools in machining Inconel 718. This is attributed to the larger chip formation component at a lower shear angle and deformation below the tool. TiCN coating proved to be more suitable for milling Inconel 718 than TiN coating due to the fact that lower shear stress was presented.