Temperature Measurement with Indexable Inserts via Functional Coating in Turning Processes

Process temperature possesses a significant influence on the wear behavior and cutting quality of cutting tools. Conventional temperature measurement systems apply either an optical approach or the integration of thermocouples into the tool. Radiation measurement methods, such as ratio pyrometers, can cause problems in flood cooling, as the line of sight is interrupted consistently. The application of optical fibers or thermocouples through the indexable insert leads to reduced material strength. Alternatively, the integration of such structures through the workpiece limits the time resolution of the measurement, as the fiber only meets the tool once per revolution. Instead, the measurement system proposed in this paper consists of multiple coating layers forming a thermocouple-like measurement system. This novel measurement principle is calibrated and furthermore applied to turning processes. The results show that multiple indexable inserts with different Seebeck coefficients are in good agreement regarding the final cutting temperature of the reference process.