MACHINABILITY ESTIMATION BY DRILLING MONITORING

Abstract

This article describes the development of a methodology to measure the specific cutting energy (SCE) in drilling. The SCE allows characterizing and the machining process, thus obtaining a technologic approach that allows to carry out a planning of the chip removal process. The main frame of this machine consists of a pedestal drill, instrumented with: a meter, a motor that controls the spindle speed, safety elements such as limit switches and an active power meter coupled to the drill motor. The mechanical power is calculated indirectly through the active power. To this end, it must have a previous calibration with a torque dynamometer to reoced theoutput curve and, subsequently, display the relationship between the mechanical power and the active electrical power. To validate the capability of this method, the EEC of three different materials is evaluated, an aluminum 7075-T6 and the steels C45E y 34CrNiMo6. It has been verified that the estimated SCE values correspond to those described by the literature. The influence of several parameters, like the cutting speed and the feed rate, on the SCE allows to estimate the sensitivity of this method. Finally, this works shows that the SCE in steel increases with the increase of the feed rate, whereas in aluminum the behavior is the opposite, the SCE decreases as the feed rate increases. Keywords: Specific cutting energy, material removal rate, cutting power, feed rate, drilling.