Project about continuous monitoring of polyurethane curing process in the shoe industry

In the shoe industry, one of the most important aspects in the composites manufacturing process -like the polyurethane (PU) soles- is the basic components quality. At present, the main quality control techniques consist of mechanical and physicochemical tests performed on the manufactured products. For this reason it is not possible to modify the reaction process (for example, adjusting basic components ratios) in order to adjust it to different conditions. These analyses are performed a posteriori and sometimes involve a great quantity of defective manufactured products, with a great loss of competitiveness.

For this reason, the microwave area (DIMAS) of the research institute ITACA (Universidad Politécnica de Valencia) is participating with A&CN and INESCOP (Footwear Technological Institute) in the project “ Industrial pre-installation of microwave sensors for continuous monitoring of polyurethane curing process” (TRACE TRA2009_0252_01)”, financed by the Spanish Ministry of Science and Innovation.  The objective is to provide the industry with a novel microwave sensors system which allows performing a continuous and real time control on the PU components and the manufacturing process. This system detects any change in process conditions and it is possible to adjust process parameters to obtain high quality products together with an efficient use of raw materials. This substantially improves the technological capacity of this sector enterprises.

The developed system consists of several microwave sensors allocated near the components tanks and inside the moulds which are already used in the PU manufacturing process. The sensors system allows a continuous, real-time, non-contact and non-destructive control of components quality and process conditions as well. It is also possible to include the information of the reactions occurring inside the moulds. Therefore, this solution provides the manufacturing process with the necessary traceability to gain efficiency.

During the project, interesting results have been published in international journals and congresses:

  • B. García-Baños et al., “Microwave Sensor for Continuous Monitoring of Adhesives Curing” 13th International Conference on Microwave and RF Heating, 2011, Toulouse.
  • B. García-Baños et al., “Dielectrometría de microondas para la monitorización continua del curado de adhesivos” 11th  Congreso de Adhesión y Adhesivos, Madrid, 2011.
  • B. García Baños et al., “Microwave sensor system for continuous monitoring of adhesive curing processes” Meas. Sci. Technol. 23 (2012) 035101 (8pp).

Spanish Version