Cutting forces and tool wear investigation during turning of sintered nickel-cobalt alloy with CBN tools

Abstract

This article describes issues related to the machining of parts made of sintered nickelcobalt alloy. Longitudinal turning with a CBN (cubic boron nitride) tool was analyzed. The results of experiments showed the influence of cutting parameters in the field of finishing machining on the values of cutting forces and specific cutting force, taking into account the wear of the cutting edge. Measurements and analysis of the topography and roughness parameters of the machined surface, as well as the cutting tool wear, were presented. The microscopic examination showed that the average grain size of the sintered nickel-cobalt alloy was 3.22 ± 0.1 (µm). The presence of the hardening state variability of the material during machining, as well as the value of the cutting force fluctuation as a function of the tool wear VB, were stated. The specific cutting force values increased to a small degree for the tool wear in the range of VB = 0-0.2 mm, and reached similar values in the range kc = 5500-7500 N/mm2. The specific cutting force values increased significantly for wear VB > 0.2 mm and were characterized by a large variability. The occurring phenomena were analyzed and several explanations were proposed. A recommendation was developed for the machining of parts made of sintered nickel-cobalt alloy. The Taguchi method was used in the experiment methodology.