A burnishing process based on the optimal depth of workpiece penetration

Abstract

This paper deals with the problem of defining the trajectory of a stiff burnishing tool that would be optimal from the point of view of surface quality. The basic goal of this work is to gain an insight into the very process from the microscopic aspect, with the primary focus on material flow and roughness variations. Based on theoretical considerations, we planned an experiment with the aim to verify the initial hypotheses about the analysis of roughness change and a determination of the optimal depth of the workpiece penetration. Through matching and the superposition of surface profiles formed at various contact pressures, i.e., various burnishing forces and various penetration depths of the burnishing ball into the profile roughness, the phenomenon of roughness change was explained. Theoretical assumptions related to a determination of the optimum tool trajectory have largely been confirmed from the point of view of surface quality. The balls within the stiff tool system, which follow a predetermined depth of penetration into the roughness profile, very likely provide optimum surface quality, regardless of the initial machining. Based on experimental results, it is highly possible that the depth of the penetration of tool (burnishing ball) should equal the roughness profile height of the previously machined surface. The analysis of results obtained by the measurement of the surface roughness and the super-positioning of the profiles obtained by burnishing with various burnishing forces, significantly contributed to the explanation of the roughness peaks' deformation phenomenon. The proposed burnishing method could be of special importance in the burnishing of roughly machined surfaces, where Rp reaches high values. Investigations presented in this paper open a number of new directions, such as the testing of a stiff tool system with various workpiece materials and burnishing regimes, with different surface roughnesses as the result of the initial machining. We believe that the proposed model can significantly improve our present knowledge of the burnishing process.