Development of in-Process Tool Wear Monitoring System for CNC Turning

Abstract

The aim of this research is to develop an in-process tool wear monitoring system for CNC turning machine. The exponential decay function is employed to represent the relation between the nominal specific cutting resistance and feed rate. An index value a in the exponential decay function is defined to estimate the flank wear, which is equivalent to the rate of increase in the nominal specific cutting resistance at zero feed rate as compared to that at infinite feed rate. In order to obtain the characteristic value a, the additional cutting cycles is proposed here to alter the feed rate deliberately during the normal cutting cycle to measure the cutting forces and identify the rate of increase in the nominal specific cutting resistance at smaller feed rates. Series of cutting tests were carried out to estimate the flank wear, and it is proved that the index mentioned above can be a good measure of tool wear, even though the depths of cut, the cutting speeds and the cutting tools, as well as the work materials are different.