Flank wear of twist drills and surface quality of holes in hard-to-cut materials by electric hot drilling

Abstract

In this study, an electrical heat-assisted method was adopted to drill a small hole (diameter of 1–3 mm) in hard-to-cut materials, namely, 1Cr18Ni9Ti stainless steel and ZGMn13 high-manganese steel. The flank wear of the twist bit and the surface quality of the small hole were investigated. The relationships among the flank wear, feeding, heating current, and cutting speed were analyzed quantitatively. Flank wear of twist drill directly affected the service life of the drill used in electric hot drilling. The dynamic effects of heating current, cutting speed, and feed rate on the surface roughness and machining hardening of the hole-wall are also discussed. Experimental data indicated that the surface roughness after electric hot drilling can also be obtained by coarse grinding and the surface hardness of the hole-wall had no obvious change. These findings showed that electric hot drilling has irreplaceable advantages in improving the service life of the drill bit and surface quality of the hole-wall.