Use of electrical power for online monitoring of tool condition

A universally applicable and reliable method for online monitoring of tool condition is presented. This method is based on monitoring the differential electrical power consumption. In this technique the power for running spindle motor is nullified and only the power required for actual drilling process is recorded. Therefore, unlike other conventional electrical power monitoring systems, this technique can be used for both small and big motors. A three-level-three variable (drill diameter, speed, and feed rate) factorial design experiment was conducted on mild steel to asses the sensitivity of detecting tool wear for drilling process based on this method. The results show that the differential electrical power is a better indicator of tool wear than conventional mechanical power method. The findings were also verified using composite materials such as carbon, Kevlar, and glass fiber reinforced plastics. This method can be effectively used to verify and/or determine the maximum permissible wear in drilling materials.