First results on polyvinylidene fluoride film-based sensors for fault detection in leather and rubber membranes used in footwear manufacturing

Footwear manufacturing is probably one of the industries that has undergone the least change in the current industrial revolution towards digitalization. The manual technique of the production process, coupled with its high specialization with machinery - that is often designed specifically for the application - are some of the reasons why this sector has seen little change in recent years. However, as in all industries, there are needs where technology can make a significant difference. In this case, the use of flexible piezoelectric sensors made of Polyvinylidene fluoride (PVDF) material, able to adapt to a complex volumetric surface, has been studied for the detection of faults in leather and rubber membranes used in the manufacture of footwear. These failures cause quality nonconformities as well as delays in production. In parallel, a finite element modelling has been developed and validated. The results obtained from the tests carried out, show a coherent response between the PVDF sensor and the reference strain gauge, with high linearity and very low bias and error. These results are promising to consider the integration of PVDF sensors in predictive maintenance applications, which will allow the prediction of failures and degradation of rubber and leather membranes.