Surface finish on hardened bearing steel parts produced by superhard and abrasive tools

Abstract

New technological process consisting of hard turning (HT) followed by abrasive machining, in place of the widely used method in industry, i.e., hard turning versus grinding, has lately been launched in the automotive industry. This is because, many transmissions parts, such as synchronizing gears, crankshafts and camshafts require superior surface finish along with appropriate fatigue performance. This paper provides a comprehensive characterization of part surface finish produced in dry turning of a hardened AISI 52100 bearing steel using mixed ceramic (MC) and PCBN tools, and also its modification after special abrasive finishing operations including superfinishing (SF) and belt grinding (BG). In this investigation, some important 2D and 3D surface roughness parameters, as well as profile and surface characteristics, such as the amplitude distribution functions, bearing area curves, surface topographies and contour maps obtained for the four surface types selected, were determined and analyzed. Experimental data gained during measurements indicate that each of the finishing abrasive processes provides a specific set of surface topologies. The transformation of bearing properties of surfaces, generated through two optional PCBN HT-BG and MC HT-SF machining sequences, are highlighted. As a result, the modifications of surface profiles achieved by means of special abrasive machining operations can distinctly improve the bearing properties of previously hard turned surfaces, and exemplarily, they shorten the running-in period.