Analysis of the Influence of Superfinishing on the Surface Topography of Ground Cemented Carbide Rods

Abstract

The industrial relevance of high quality bore holes for parts of the automotive industry rises due to the growing requirements to limit CO2 emissions and therefore the tendency of using elevated pressures for the fuel injection. To fulfil these requirements the bores must have a very high surface quality. If large length-to-diameter (l/d) ratios are necessary, e.g. in machining of fuel injectors, deep hole drilling with single-lip drills (SLD) is mostly used to reach good surface qualities. Due to their asymmetric shape one component force acts as a normal force on the circumferential guiding pads of SLDs. For difficult to machine materials the mechanical loads increase as well. This results in a higher wear of the circumferential guiding pads of SLDs, which leads to reduced surface qualities. Many investigations have dealt with the influences of a cutting edge preparation to increase tool life and process parameters to optimise the productivity. Up to now no research work has dealt with the influences of the surface topography of the circumferential guiding pads on the produced bore quality. Thus, in this paper a superfinishing process is applied on cemented carbide rods as model workpieces with the circumferential shape G of SLDs to examine the influences of e.g. the grain size of the finishing film and the pulley hardness on the surface topography and the material removal at the circumferential surfaces.