Investigation of the Effect of U Drills with Different Properties on Thrust Force, Torque and Spindle Load

Abstract

Udrills are indexable insert drill commonly used in drilling operations. It is estimated that the market share among drilling tools is around 53%. They are produced in the same nominal diameter but in different lengths. There are usually two cooling holes, one behind the central insert and the other behind the peripheral insert. However, in some Udrills, an extra third cooling hole is drilled by the manufacturer. In this study, the effects of different length/diameter ratios, extra coolant hole and drilling parameters on thrust force, torque and spindle load were investigated in order to determine the effect of differences in U drills on hole drilling. AA 2024-T351 was drilled to a depth of 40mm using Udrills with a body diameter of 20mm. A total of 4 Udrills (3D, 4D, 4De, 5D) were used. Three feed rates (0.06, 0.09, 0.12mm/rev) and three cutting speeds (200, 250, 300m/min) were used in the experiments. According to the Anova analysis, it was concluded that while the length/diameter ratio of Udrills had an effect of 56.97% on thrust force and 21.46% on spindle load, it was not effective for torque. The 4De Udrill with extra coolant hole gave 34.2% higher thrust force, 0.3% higher torque value and 26.53% lower spindle load compared to the 4D Udrill without extra coolant hole.