Super FF coat carbide and Cubic Boron Nitride (CBN) inserts in high-speed fine machining of grey cast iron: Parametric study on surface integrity, tool performance, and wear analysis

This study investigates a critical challenge in high-precision manufacturing: tool wear and surface integrity during high-speed fine boring using a milling-type configuration on grey cast iron engine block liners, a crucial operation in the automotive industry where both dimensional stability and subsurface performance are essential. To provide a deeper understanding of cutting tool performance under such demanding conditions, a comparative experimental investigation was conducted using Chemical Vapor Deposition (CVD) Super FF Coat carbide inserts and Cubic Boron Nitride (CBN) fine inserts. Tool wear progression, tool life, and surface integrity were systematically evaluated through dimensional analysis, digital microscopy (Dino-Lite), and advanced Scanning Electron Microscopy coupled with Energy Dispersive Spectroscopy (SEM-EDS). Machining tests were performed at a constant cutting speed ( V c ) of 288.88 m/min with varying feed rates ( f ) at 0.18, 0.2, and 0.25 mm/rev to compare the performance of both tool types in high-precision finishing operations. SEM-EDS analysis revealed that the CVD carbide inserts predominantly experienced abrasive and adhesive wear, with significant material transfer from the grey cast iron (GCI), resulting in dimensional deviations beyond acceptable tolerances. In contrast, the CBN inserts exhibited mainly abrasive wear with minimal adhesion and oxidation, contributing to greater dimensional stability and extended tool life. Surface roughness ( Rz ) measurements showed that the carbide inserts initially provided better surface finishes; however, CBN tools demonstrated superior durability despite producing slightly higher roughness values. These findings highlight the critical role of tool material selection and feed rate optimization in enhancing machining efficiency, extending tool life, and maintaining surface integrity in fine boring applications. The results are particularly relevant for enhancing process reliability and efficiency in automotive and high-precision manufacturing sectors.