Machinability Study of Multilayer Coated Tungsten Carbide Inserts Using Chemical Vapor Deposition Techniques

This study focuses on optimizing machining parameters and conducting a comprehensive performance analysis of two distinct cutting tools, Tool A and Tool B, each equipped with advanced multilayer CVD coatings on tungsten carbide inserts. Tool A features a coating composition of TiN/MT-TiCN/TiCN/Al2O3, while Tool B boasts an additional layer of TiOCN, augmenting its coating structure to TiN/MT-TiCN/TiCN/Al2O3/TiOCN. The performance evaluation of two CNMG120408UN cutting inserts, following CVD coating, was meticulously carried out using SEM and EDAX analysis to rigorously ascertain coating thickness and composition. The machining process involved dry turning of EN8 steel, with varying cutting speeds (180, 240, and 300 m/min), feeds (0.2, 0.3, and 0.4 mm/rev), and depths of cut (0.5, 1.0, and 1.5 mm). Utilizing the Taguchi L9 array methodology, critical responses such as flank wear (F), nose wear (N), surface roughness (Ra), and cutting zone temperature (T) were quantitatively measured in a systematic manner. Comparative analysis unveiled Tool B's remarkable superiority, exhibiting an impressive 18.18% reduction in flank wear, which significantly extends tool longevity. Tool A, conversely, excelled with a commendable 13.33% reduction in nose wear. Both tools consistently maintained comparable surface roughness levels. Noteworthy was Tool B's exceptional temperature resistance, displaying a remarkable 31.57% improvement attributed to the additional TiOCN layer's high-temperature capabilities. This study firmly establishes Tool B as the standout performer, excelling in temperature resistance and flank wear reduction. Meanwhile, Tool A distinguishes itself for its superior nose wear reduction. These quantitative findings furnish valuable insights for manufacturers seeking to enhance tool selection and machining efficiency. © 2023, The Institution of Engineers (India).