Steel integrated thin film sensors for characterizing grinding processes

We present a workpiece with integrated thin film resistive sensors to measure temperature during grinding. This is useful in examining the correlations between the loads occurring in the machining process and the subsequent material modifications of the workpiece. However thin film resistive micro structures have not been integrated in steel yet to measure loads during grinding. To build up the sensorial workpiece, thin film resistive sensors are initially fabricated on a steel inlay on wafer level and later integrated in the workpiece. Therefore different bonding techniques and adhesives are evaluated. The sensorial workpiece is then used to characterize the grinding process in which in-situ measurement of temperature is done by recording and analyzing sensor data. Also a macroscopic thermocouple is integrated in the workpiece, to compare the measurement with the thin film sensors. Due to the integration process of the sensors, foreign material (adhesive) is brought into the workpiece changing its physical behavior like the temperature conductivity in comparison to a non-sensorial workpiece. The most challenging part is to quantify this foreign body effect which has not been done in literature yet, to get a strong significance of the measurement results. This is why we consider the grinding process theoretically by the help of a finite element modeling and we calibrated the simulation with measurement results. Within this the measurement results can be recalculated in a way as if there were no sensors in the workpiece.