Hole quality in drilling of annealed inconel 718

Abstract

This paper reports the results of an investigation on the machinability of Inconel 718 in drilling operations in terms of quality of drilled holes. The size and out of roundness of drilled holes was measured and analyzed after drilling at different speeds and feeds using TiAlN coated, PM HSS stub drills with two different geometries. The performance of drills with split point geometry was compared with the one with conventional geometry under wet conditions. A cutting speed in the range of 10-15 m/min and a feed rate range of 0.05-0.1 mm/rev was established prior to this investigation. Results indicate that single-layer TiAlN coated drills operated optimally in terms of hole diameter and roundness at a cutting speed of 10 m/min and a feed rate of 0.075 mm/rev while multi-layer TiAlN drills gave optimal results at the same cutting speed but at a feed rate of 0.05 mm/rev. The coated drills with split-point geometry outperformed the drill with conventional geometry with regards to both the hole size and out of roundness of the drilled holes.