The influence of twist drill main cutting edge preparation in drilling process

Abstract

In order to improve the performance of a twist drill, one must understand some aspects involved in drilling process that are not commonly addressed, such as the micro geometry employed in the tool's tip sharpening and the protection of the main cutting edge. The edge of the twist drill can be protected by rounding, chamfering or the combination of both. This paper analyzes the influence of edge preparation by two different methods, honing and chamfering on a solid cemented carbide twist drill ø11 mm, used in the machining and processing of SAE 4144M hardened and tempered steel (hardness: 380HV1), with a 100% martensitic structure, employed in injection pumps for diesel engines. The hole's diameter, position deviation, roughness and roundness revealed significant differences in results. The tool with the honed edge presented lower wear values, when compared to the tool with the chamfered edge.