High frequency (50–120) MHz, ultrasonic, AIN-sensors have been successfully applied to the study of wear, chipping/breakage and temperature of triangular ceramic and carbide inserts. These sensors readily differentiate between signals from wear and chipping/breakage and, in flight-identify the damage location with simultaneous measurement of signal amplitude and transit time. The signals are unaffected by the machining process. The temperature of the chip/tool interface can be readily obtained during the cutting process by monitoring the transit time. Preliminary studies suggest these sensors also monitor the hardness of the workpiece and the chatter during the cutting. A specially-designed ultrasonic process-control system with 100 ps time resolution with data collection speed 1–10 kHz was necessary to observe the on-line data. The same system integrated with a focused transducer can be used to follow the workpiece dimension and surface finish, on-line. The ultrasonic, process control system that has been developed is robust and can be used for other NDE applications with a resolution of sub-micron thickness. It can also monitor residual stresses.
On-Line Tool Monitoring of Tool Wear Chipping/Breakage and Temperature Using Ultrasonic Sensors