Tribological Properties of a Magnetorheological (MR) Fluid in a Finishing Process

This article examines the tribological properties of a magnetorheological (MR) fluid in a finishing process. The MR fluid under investigation contains about 85 wt% of micro-sized carbonyl iron (CI) particles and about 15 wt% of water and surfactant(s) compound. A semi-empirical material removal model is proposed for the description of the tribological behavior of the MR fluid in the finishing process by considering both the solid- and fluid-like characteristics of the fluid in a magnetic field. Additionally, Archard's theory and Amonton's law of friction are applied to the model, which is completed by experimental efforts to identify the relationship between the effective friction coefficient and the ratio of the interfacial particle velocity to the imposed pressure on the workpiece surface. It turns out that the effective friction coefficient has a linear relationship with this ratio. The validity of the proposed model is supported through material removal rate measurements. It is also shown that the proposed model is substantially different from the conventional Preston equation in that the material removal rate is not only a function of the product of the applied normal pressure and relative velocity, but it also strongly depends on the square of the relative velocity.