Influence of the critical cutting speed on the surface finish of turned steel

Variables such as feed rate and the tool's nose radius and cutting speed can provide a control on the quality and the surface finish in a given machining process. There is also a physical phenomenon known as 'built-up-edge', which is seen in certain cutting speed ranges that directly affects the surface finish in turned steel workpieces. This paper intends to shed a new light on the already existing information about surface finish in turned steel pieces. Different types of steel (AISI 1020, AISI 1045 and 4140) were studied, where the influence of variables such as cutting speed and hardness of the material helped establish the critical cutting speed (value at which the built-up-edge phenomenon was observed). Additionally, a mathematical model that relates the roughness value and cutting parameters and a general mathematical model for roughness, which relates the hardness of the materials, was established. (C) 1998 Elsevier Science S.A. All rights reserved.