IMPROVEMENT BY BALL BURNISHING FOR INTERNAL TURNED SURFACES

ABSTRACT The work in the presented paper was confined to one material; aluminium alloy. Holes were internally turned to get different sizes for different grades of surface finish range of Ra. 0.7 to 9 μm, hard smooth steel ball was used for burnishing; first forcing it through the hole, “greased”, then forcing it again “dry” as a second cold, ironing pass. The main result achieved was determining the optimum values of interference between the burnishing ball and hole yielding the largest percentage improvements in the hole qualities regarding: (a) Smoother surface finish parameters. (b) More Bearing metal percentage. (c) Better hole roundness. (d) Better hole straightness. (e) Higher surface hardness. (f) Better closeness of hole final size to the aimed-at value.