Efeito da mesogeometria da broca e das condições de lubrirrefrigeração sobre o acabamento em aço DIN S700MC

Abstract

This study presents an investigation on the behavior and effect of the machining process by drilling through a DIN S700MC steel alloy, correlating the preparation of cutting edge geometrywith different cooling-lubrication conditions, and focusing on the surface finishing of the machined part. In this context, experimental tests were performed with different coolinglubrication systems (abundance, MQL, and dry) using solid carbide twist drills, coated with titanium aluminum nitride, with or without meso-geometry preparation (roundings). As response variables, the texture (roughness), the layer affected by heat throughout the hole, and microhardness and burr dimensional profiles were assessed. The results indicate a significant reduction of roughness values when using the rounding drill flank, face and guides. Statistically, this result was not influenced by the different cooling-lubrication. Regarding burr dimension generated by the process, the tool with no meso-geometry preparation presented the same values along with the application of fluid in abundance (emulsion). In the analysis of the layer affected by heat, the tool with meso-geometry preparation presented lower values of the affected layer (microstructure change) and, statistically, there were no significant variations between the application of fluid in abundance and with minimum quantity of lubricant. In the evaluation of microhardness profile, there was no clear conclusion about the influence of thermal and mechanical requirements on the region close to the hole edge, because of the effect of edge deformation caused by microindentation.