Helical groove texturing on flutes of twist drill and hole machining enhancement

Surface texturing is a technology that effectively controls tribological performance between interacting surfaces, and research is actively being conducted to apply these advantages to cutting tools. However, most of the research has been applied to turning inserts and rarely to twist drills. In addition, the latter research was conducted without reflecting the helical shape of the twist drill. Therefore, the objectives of this study were to create helical grooves on the flutes of twist drills by accurately reflecting the tool shape and then assess their drilling performance. To achieve helical groove texturing, laser micromachining equipment with suitable automatic axes was developed, enabling the creation of uniform helical grooves. Drilling experiments that involved producing closed holes with a depth of 60 mm were performed using both conventional and helical groove textured drills at a cutting speed of 50 m/min and feeds of 0.03, 0.05, and 0.07 mm/rev. Each feed condition was performed three times on aluminum alloy under a wet environment. The results indicated that the textured drills enhanced chip evacuation and machinability by reducing adhesion and friction between the flute surface and the chips compared to conventional drills. When machining with the textured drills, there were different behaviors in terms of thrust force and torque. Excluding cases where chip clogging occurred, the textured drills exhibited higher thrust force and lower torque compared to conventional drills under all feed conditions.