The Influence of Twist Drill Main Cutting Edge Preparation in Drilling Process

Moises Izaias De Santana,Milton Luiz Polli

doi:10.1590/1516-1439.352914

Moises Izaias De Santana, Milton Luiz Polli

Open Access

https://doi.org/10.1590/1516-1439.352914

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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 O11 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.

Highlights

The appropriate selection and application of cutting edge protection are the basic ingredients for the successful manufacturing with proper performance when using a cemented carbide tool (WC-Co)
This paper aims to understand the influence that cutting edge preparation has on the quality of the obtained hole
According to Denkena et al.[3], the trumpet shape presents the best performance regarding lifetime in studies using cemented carbide (WC-Co) inserts, while Heo et al.[7] and Biermann et al.[9] do not even mention the shape of the profile applied to the cutting edge

Summary

Introduction

The appropriate selection and application of cutting edge protection are the basic ingredients for the successful manufacturing with proper performance when using a cemented carbide tool (WC-Co). One of the aspects that have guided researches and innovations for high-performance tools is the preparation of the main cutting edge[2]. Adapting the surface of the cutting edge as well as the cutting surface for a subsequent coating process of the tool or improving the contact zone for machining[2]. The geometry of the edge preparation influences the thermomechanic aspects of the cutting process. From which it is worth pointing out the format of the deformation zone, the temperature distribution in the cutting process, the machining forces, the chip formation and flow, the superficial integrity of the work piece and the tool’s resistance to wear[2,3,4,5,6]. Due to its importance in the machining field, cutting edge failures and some benefits related to the protection of the cutting edge achieved by different processes have been the subject of studies by several researchers[7,8,9,10,11,12]

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