Thin film sensor systems for use in smart production
For further success of the fourth industrial revolution, it is necessary to acquire detailed process data parallel to data processing. For measuring exact data of the production system, the sensor systems has to be integrated in the decisive area of the production process. This leads to an increasing demand for sensor systems that can directly be applied on tool or component surfaces, which are in high loaded contact with the workpiece or counterpart. For this reason, Fraunhofer IST develops thin film sensor systems by physical vapor deposition (PVD), plasma enhanced chemical vapor deposition (PECVD) and structuring technologies with high hardness, high wear resistance, low friction coefficient and a high load capacity that are very small and only few mm thick. These multisensory thin-film-systems can record force, temperature and their distributions directly in a production system or a tool surfaces with spatial resolution, so that both inline condition monitoring and predictive maintenance are possible. For such a multisensory thin film system the thermoresistive and piezoresistive properties of metal or hard coatings and diamond-like carbon layers (DLC) are used and has to be well adapted and arranged e.g. by structuring processes. Different thin film sensor types, their manufacturing as well as examples for application and the sensor performance in industrial production processes will be introduced. A thin film sensor on a tool segment for injection molding of natural fibre reinforced polymers will be shown. This thin film sensor system with high wear resistance allows measuring the temperature distribution on the mold surface and the monitoring of the melt front movement. A further interesting example are smart washers for static and dynamic control of the true clamping force of screw connections. Prospectively, these various thin film sensor systems could be a capable contribution to establish an intelligent, digitalized and smart production.