An investigation into the ball burnishing of an AISI 1045 free-form surface

This paper reports on the work undertaken in the ball burnishing of a free-form surface made from AISI 1045 medium-carbon steel. A geometric model of a free-form surface was generated using the catia solid modeler running on an IBM 5080 work-station. The NC codes generated were then down-loaded onto a 4-axis vertical machining centre for rough-milling, ball-end milling and finally ball burnishing. Preliminary experiments with 3-D curved surfaces indicated that grease is a better lubricant than machine oil in the ball-burnishing process. Using a full factorial experiment, it was found that the quality of surface finish attainable in the ball-burnishing process is affected significantly by the depth of penetration, the burnishing speed and the feed-rate. Four two-factor and four three-factor interaction effects were found to be significant at the 99% confidence level. The results of the ball-burnishing experiments on 3-D curved surfaces were analysed and a set of machining parameters selected therefrom were applied to the ball burnishing of the free-form surface. The best surface finish of the free-from surface obtained was estimated to be between 0.29 and 0.55 μm R tm.