Analysis of the life of cemented carbide drills with modified surfaces

Abstract

The performance of cemented carbide cutting tools during machining is influenced not only by the mechanical properties of the coating and substrate but also by the topographies of their surfaces. A tool with good coating and substrate properties but unsuitable topographies may exhibit accelerated wear and, consequently, impaired performance. In this work, drills coated using physical vapor deposition (PVD) were produced with different substrate textures, which in turn generated different coating textures. The surface roughness values of the coated drills were measured together with the residual stress at the interface between substrate and coating. Drilling tests were performed and tool wear was measured during the machining process. Two different tool coatings were studied: TiAlN and TiAlCrSiN. The goal was to study how the characteristics of the substrate and coating (material, surface topography, and residual stress) influence tool life. Tool life experiments were carried out using drilling tests in AISI 1548 steel, which is often used in crankshafts. The primary tool wear mechanism was attrition in all the drills. The main conclusion of this work is that the tool with the lowest roughness and a TiAlCrSiN coating had the best performance in the conditions tested here.