Modelling of surface roughness in a new magnetorheological honing process for internal finishing of cylindrical workpieces

Abstract

A new magnetorheological honing (MRH) process has been developed for internal surface finishing of cylindrical workpieces with different diameters. The process makes use of the tool with radial polarized curved permanent magnet strips and a smart magnetorheological (MR) polishing fluid for finishing the internal surface of the cylindrical workpieces. The MRH tool has the uniqueness that its radial curved permanent magnets can move inwards or outwards just like a honing tool so that the different diametric sizes of the internal surface of the cylindrical components can be finished. In the present work, a mathematical model has been developed for predicting the change in surface roughness while finishing the internal surface of ferromagnetic cylindrical workpieces. An analytical approach is adopted to evaluate the magnitude of magnetic flux density at different points in the working gap where MR polishing fluid is present. While finishing the internal surface of ferromagnetic cylindrical workpieces, a magnetic field is also contributed in the working gap due to the effect of iron particles (present in the MR polishing fluid) and the ferromagnetic cylindrical workpiece. The present developed mathematical model evaluates the magnitude of magnetic flux density in the working gap by also considering the contribution of the magnetic effect of iron particles and the ferromagnetic cylindrical workpiece. Theoretically calculated magnetic flux density distribution in the working gap is validated with the experimentally and also through finite element (FE) analysis using Maxwell Ansoft V13 software. With the evaluated values of magnetic flux density at various points in the working gap, the magnetic normal force exerting over the active silicon carbide (SiC) particle has been evaluated. The computed magnetic normal force exerting over the active SiC particle is utilized to calculate the removal of material in terms of decrease in surface roughness values with various finishing cycles. Also, the developed mathematical model for the present MRH process has been validated by performing the experimentations with same parameters and conditions as selected in modeling for the different number of finishing cycles. Results acquired from the mathematical model are found in close relation to the results obtained from experimentations with the maximum percentage error of 8.06% and least of 1.03%. The developed mathematical model for MRH process can be used to predict the process's finishing performance for various ferromagnetic cylindrical workpieces which can make it useful for industries.