Development of a new precision internal machining process using an alternating magnetic field

Imparting compressive residual stress to a surface improves the fatigue structural integrity of components, which is particularly important for components used in such critical applications as high-pressure gas or liquid piping systems. This paper proposes a new precision internal machining process that controls the surface integrity of internal surface of these components. This process utilizes an alternating magnetic field to control the force and dynamic motion of the tools needed for machining. An experimental set-up was developed to test the processing principle. This study characterizes the in-process tool behavior—that is, the relationships between the magnetic field, the tool properties, and the tool behavior—and reveals the properties of the tools required to achieve the desired results: magnetic anisotropy and a specific geometric restriction. The surface roughness, hardness, and residual stress measurements following machining experiments demonstrate the effects of the tool behavior on the machining characteristics. This paper also proposes methods to obtain desired surface characteristics.