Material-integrated thin-film sensors to measure strain in grinding processes

The doctoral thesis presents a material-integrated thin-film sensor system designed to enable real-time, in situ monitoring of process data during manufacturing processes. Resistive sensors with a meander design were manufactured on steel substrates using a conventional microfabrication process. The resulting "sensor inlay" consist of rectangular steel pieces that are obtained from the fabricated substrates and contain the sensor layer imprinted in them. The sensor inlays were then glued into a groove that is pre-machined on top of a standard workpiece using epoxy adhesive. The workpiece and the sensor inlay are made of the same steel. This creates the so-called ‘sensor-integrated’ workpiece. The ‘sensor-integrated’ workpiece was then used for measuring in-situ strain in the workpiece material in outer-diameter cylindrical grinding and flat surface grinding. At each grinding cycle, one measurement was recorded continuing until the sensor layer was eventually damaged. This recorded data provided insights into strain dynamics on the workpiece material throughout the grinding process. The broader significance of this research lies in its potential applications beyond grinding, as it enables real-time monitoring of internal parameters in various machining processes. Such technology offers significant potential for improving process control, precision, and quality in other manufacturing processes and is not limited to grinding alone. Moreover, it could drive innovations in both thin-film technology and sensor integration in materials beyond traditional silicon technology.