Turning of Hardened Steels

Abstract

An investigation is reported of the face turning process for machining a hardened bearing steel using CBN cutting tools. Studies were made of the specific energy, the chips generated, the tool inserts used, and the machined surfaces. The specific cutting energy was found to be directly related to the maximum undeformed chip thickness, which is attributed to the plowing at the engaged cutting edge. Most of the chips generated were saw-toothed, which can account for the relatively large chip area ratios measured. The measured surface roughness and the ratio of 10 point to arithmetic average roughness, R z / R a , were comparable to their predicted ideal values for rougher surfaces with larger feeds, but the values tended to become progressively bigger for smoother surfaces with smaller feeds. The incidence of white layer generation decreased with a sharp tool at faster cutting speeds.