Estudo comparativo do comportamento entre brocas alargadoras e processo de alargamento na usinagem do ferro fundido cinzento GG30

Abstract

The conventional drilling process is the most used among all machining processes. It is usually applied for holes with lower quality surface requirement, with roughness around 6.3 Ra. Higher quality drilling process, with 0,8 Ra, use other drilling process such as, reaming, boring, among others. These processes are more expensive because of the cost of cutting tools and especially because of the operational time. Aiming to reducing the machining time and improve the holes surface quality, tool manufacturers have been developing and improving geometries able to combine the drilling operations with reaming operations, optimizing the productivity. The drill reamers, among other characteristics, are manufactured with the highest number of cutting edges, usually with eight edges based on tool’s diameter. The main channel have high trimming functions and high chip removal, while the other channel reduce the surface roughness, removing less material and providing greater tools stability during the machining process. The aim of this paper is to study the behavior of the machining process through drill reamers with four and six cutting edges, taken into consideration holes with roughness up to o,8 Ra in the material cast iron GG30, comparing this performance with conventional reamers’ process. The preliminary results has indicated that by using drill reamers, over 30% of the machining time can be reduced comparing to conventional reamers’ process, keeping roughness values around 0,8Ra, merging the speed of conventional drilling’ process with the surface quality of the holes obtained in conventional reamers’ processes.