The behaviour of static torque and thrust due to tool wear in drilling

Abstract

Motor currents from spindle motor and feed motor (Z-axis) have been measured to estimate the static torque and thrust in drilling. A large number of test series has been conducted to find which of the two parameters, torque or thrust or both increase due to excessive drill wear and breakage. It has been found that in drilling with twist drills of diameters between 6mm and 12mm, either the static torque or the static thrust or both substantially increase as a result of excessive tool wear and tool fracture.