Fluctuations in the upstream process chain and the ultrasound welding process cause fluctuations in joining quality. Therefore, defects in welding seams are currently considered as unavoidable. It is not possible to conduct a non-destructive inspection of the join to assess product features, such as the strength of the welded join. At the moment, it is still impossible to take the impact of interactions of upstream process steps on the quality of the weld seam into account in the welding process. However, it is known from experience that the majority of quality problems associated with ultrasound welding occur due to fluctuations in the injection-molding process or transport of the components. Subject to an increase in product liability and stricter competition, new methods are becoming necessary to monitor quality in this branch of industry with the aim of assessing product quality on the basis of process information.
In a joint research project, efficient system technologies are currently under development; innovative methods and techniques evaluate the quality of weld seams by identifying process fluctuations. Sensor data from the welding process is collected in cycles to define process fluctuations with significant signal parameters. Based on test series, correlations between significant fluctuations in the process and relevant changes in parameters are being established with the aid of teachable models. The aim of the ongoing research project is to develop an integrated system concept for monitoring the quality of ultrasound welding processes.