Injection moulding is one of the most important manufacturing processes for plastic products. The direct route from raw material to finished product, the very short product manufacturing time and the possibility of fully automating the process represent a sustainable advantage over other production techniques, especially in the manufacture of mass products. The metrological monitoring of the manufacturing process and the final product quality has not yet been satisfactorily solved from the manufacturers point of view. For monitoring and controlling the injection process, so-called cavity pressure sensors can now be optionally installed in the mould. However, these sensors are very expensive, sensitive, require a lot of maintenance, reduce the mould stiffness and have a negative effect on the surface structure of the manufactured component, as they typically have to be in direct contact with the moulded part. This often makes costly manual and/or mechanical component checks after production necessary to ensure the required product quality. In order to better control and monitor the manufacturing process, a novel ultrasound-based sensor technology with integrated evaluation algorithms has been developed. In addition to the process-relevant functions of the cavity pressure sensors available on the market, namely the monitoring/control of the injection process and its stability, the system can determine various additional measurement variables related to the moulded part. The method works non-invasively in relation to the moulded part, the installation in the mould is significantly simplified, information about the cooling behaviour and the internal structure of the component (density, homogeneity, filler distribution, degree of polymerisation) can be determined in real time.