Wear and surface finish studies on CVD coated tungsten carbide indexable inserts

Abstract

The present work aims at studying of the different types of wear occurring in cemented carbide indexable inserts. Chemical Vapour Deposition (CVD) coated tungsten carbide inserts were selected for the experimentation. Coating was brought about by vapor phase deposition process (CVD). TiN, TiC & Al2O3 coated grades were considered, as they are presently in wide commercial applications. Experiments have been conducted to study the flank wear, crater wear, nose deformation, built up edge formation etc., using R&D facilities at Kennametal India Ltd., Bengaluru. Experiments were conducted to compare surface finish at different feeds and different machining time. Studies indicated that the wear development and wear progression is very much slower in coated grades compared to uncoated grades. Surface finish is comparatively good in case of coated grades which are inferred using SEM. At low cutting speeds the existence of TiC Coating increases the life of the tool. Diffusion occurs as the cutting speed is increased, resulting in a high temperature, necessitating the use of a glaze that is both thermally and chemically stable (Al2O3). Wear analysis is an essential part of cutting tool application in order to assess the performance of coated layers as well as coating process. To measure the wear resistance of the material Pin on disc method is used. Wear analysis were carried out to study all the three types of wear. Experiments were conducted to record flank wear, crater wear, and Built-Up-Edge (BUE) in plain turning of EN8 alloy steel in CNC high powered lathe. Studies were extended to compare tool life of coated grades with uncoated grades. The results of the different stages of the experiments were recorded and discussed in the current study.