Influência do tratamento do gume no desgaste de brocas helicoidais de metal-duro na usinagem de ferro fundido nodular

Abstract

The performance and reliability of machining tools are significantly affected by the microgeometry of the tool. Although after grinding the tool already has good cutting capacity, it generally has micro-defects such as cracks and burrs, leading to a high degree of instability in the cutting edge. These defects increase the risk of chipping and other wear on the cutting edge, prematurely defining the end of the tool's useful life. Providing adequate cutting edge preparation is important for reducing tool defects, enabling more stable cutting and, consequently, increasing tool life. The main objective of this work is to evaluate the influence of different cutting edge preparations on the wear of cemented carbide step drills. Drills treated with the brushing process, drag finishing and also untreated drills were used. The parameters of the machining tests were not altered and the workpiece was made of nodular cast iron. As analyses, the cutting edges generated after the cutting edge treatments were evaluated, characterized using optical microscopes to check for defects and the Alicona microscope to check the size of the radius generated. After a certain number of holes had been drilled by the tools, the maximum flank wear was measured to check for wear and the types and mechanisms of wear were evaluated using a scanning electron microscope (SEM). The results showed that the treatments used were effective in treating the cutting edge, smoothing and eliminating possible defects. In terms of performance, the drills with edge treatment by brushing and drag finishing showed similar performance, and higher than the drill without edge treatment, with an average performance approximately 55% and 59% higher than drill bits without treatment, respectively. With regard to tool wear, the results obtained during the machining tests show that the cutting edge treatments applied to the drills played a significant role in controlling adhesion and abrasion wear, which are predominant in the cast iron drilling process. [resumo fornecido pelo autor]