Injection molding parts with integrated all-inkjet printed strain gauge for condition monitoring

Injection molding parts became more and more complex and especially critical components are subjected to high safety requirements. In this paper a fully functioning injection molding test specimen with integrated condition monitoring was developed by using all-inkjet printed strain gauges and back injecting them. For the printing of electrically conductive traces a commercial available Epson printer and silver nanoparticle dispersion was used. This enables the fabrication of sensor systems without the need of a photo mask. Furthermore the applicability for monitoring injection molding parts with low-cost sensor systems was investigated. Therefore several test specimens with integrated strain gauges were fabricated and tested with a tensile testing machine. With the integrated strain gauge the relative change in resistivity was measured and the resulting strain was then compared to the results of the tensile testing. In this context the gauge factor of the printed conductive traces were characterized.