The Development of Surface Acoustic Wave Sensors (SAWs) for Process Monitoring

Wirelessly interrogated surface acoustic wave (SAW) sensors can operate passively and in harsh conditions. Development of SAW sensors allows investigation of their potential to quantify measurands such as strain in aggressive environments. In this paper, a one port SAW resonator strain sensor is presented fully packaged and is shown to exhibit highly sensitive and linear responses to applied strain. The sensor detailed is fabricated on AT-X quartz, packaged using an off the shelf Kovar package, and instrumented with commercially available strain gauge adhesives. The sensor is initially presented on a characterised strain calibration platform developed in TCD with a foil strain gauge as reference technology for performance validation and comparison. The sensor is then shown instrumented with a Sandvik CNC tool holder for direct process monitoring of machining operations. The tool holder coupled with the integrated SAW strain measurement technology is calibrated using a Kistler Dynamometer in an Instron loading machine. The fully calibrated sensor is a platform for dynamic tool condition monitoring in a commercial CNC machine is then described. The work presented is to provide a basis for SAW technology in tool condition monitoring and process monitoring systems in the future.