Measurement of tool temperatures in the tool-chip contact region by embedded thin film thermocouples
Monitoring and controlling thermo-mechanical parameters in the tooling material are imperative for improving the fundamental process understanding, assuring the reliability and meeting the desired workpiece quality of material removal processes. Polycrystalline cubic boron nitride (PCBN) tools are being used heavily in machining of low carbon steel and superalloys. These processes are very sensitive to variation in local machining conditions and lack a thorough understanding of fundamental thermo-mechanical phenomena. Existing sensors to monitor machining temperatures are not suitable for process control as they are either destructively embedded and/or don't possess the necessary spatial and temporal resolution. This paper presents an approach for assessing temperature data from the close vicinity of the tool cutting edge. For this purpose an array of 9 micro thin film thermocouple sensors, fabricated using standard microfabrication methods, has been embedded into PCBN using a modified diffusion bonding technique. Experiments were performed for assessing tool temperatures under the rake face of the tool and correlating these measurements to cutting force and vibration signatures.