Investigation on tool wear and chip morphology in hard turning of EN 31 steel using AlTiN-PVD coated carbide cutting tool

Abstract

Hard turning is a well-known machining technology by which a cylindrical job of hardness above 45 HRC is machined using a single point tool. In hard turning, higher tool wear is the main issue identified by the machinist. In the hard turning activity, tool wear is severely stimulus by cutting parameters, cutting tool materials, and cutting environment. The temperature evolved in the cutting process is the prime factor to accelerate the tool wear. However, there is a requirement to control the temperature intensity by selecting suitable input turning parameters and cutting environment. However, the current research emphasizes the selection of suitable input turning parameters and suitable coated carbide tools in hard turning of EN-31 bearing steel of hardness 56 HRC in conventional flood cooling. AlTiN-PVD coated carbide insert was used to execute the turnings tests using Taguchi L16 orthogonal array, and a detailed study on tool wear and chip pattern formation is investigated. AlTiN PVD coated carbide tool performed excellently in flood cooling as maximum tool wear was found as 0.065 mm which is very less for hard turning concerns. Also, long helical and ribbon chips patterns are identified in the entire investigation. Blue color chips are identified at 240 m/min of cutting speed which confirmed the generation of higher cutting temperature in course of cutting. The present findings can be suitable for the industries that are still using a conventional cooling method in the machining of heat-treated steels having hardness 45–69 HRC.