ROLLER BURNISHING OF HARD TURNED SURFACES

In a hard roller burnishing operation, a hydrostatically borne ceramic ball rolls over the component surface under high pressures. The rough ness peaks are flattened and the quality of the workpiece surface is i mproved. When combined with hard turning, this process provides a manu facturing alternative to grinding and honing operations. The studies d etermined optimum working parameter ranges. Parameter settings were sh own to be noncritical in this process, since constant surface qualitie s were attainable over wide setting ranges. A second phase of the stud ies examined the improvements obtained for various original roughnesse s. Reductions of 30 to 50 % in mean peak-to-valley height R-z are, for example, achievable, depending on the original roughness. Structure a nalyses and residual stress measurements were used to examine the effe cts of the process on the workpiece surface zone. Hard roller burnishi ng transforms tensile residual stresses present in the surface zone af ter hard turning into compressive residual stresses. Hard roller burni shing has no effect on the formation of white layers in the surface zo ne. (C) 1998 Elsevier Science Ltd.