Spherical motion burnishing implemented on lathes

This paper presents a new method of mechanical surface treatment of external cylindrical surfaces and it is called “Spherical motion burnishing” (SMB). The axes of the workpiece and ring-shaped tool having toroidal acting surface intersect at angle θ=2°. The tool motion is superposition from a spherical motion and rectilinear translation with respect to the workpiece. The contact between the surface treated and its enveloped-tool acting surface is one of sliding friction in the presence of a lubricant. The method can be implemented on conventional machine tools, in particular on lathes by means of a relatively simple device and tool. To evaluate the manufacturing potentials of the SMB method a designed experiment has been carried out. The quality of the treated surfaces of workpieces made of low- and medium-carbon steel has been investigated experimentally. Mathematical models of the roughness and the residual axial normal stresses have been obtained on the basis of a planned experiment. The authenticity of the models has been proved on the basis of four extra tests. The method can be classified as mixed burnishing because it combines the advantages of hardening, dimensional burnishing and smoothing burnishing.