Demoulding process assessment of elastomers in micro-textured moulds

Micro-texturing is an increasingly used technique that aims at improving the functional behaviour of components during their useful life and it is applied in different industrial manufacturing processes for different purposes, such as reducing friction on dynamic rubber seals for pneumatic equipment, among others. Micro-texturing is produced on polymer components by transfer from the mould and might critically increase the adhesion and friction between the moulded rubber part with the mould, provoking issues during demoulding, both in the mould itself and in the rubber part. The mould design, the coating release agent applied to the mould surface and the operational parameters of the moulding/demoulding process are fundamental aspects to avoid problems and guarantee a correct texture transfer during the demoulding process. In this work, the lack of knowledge about demoulding processes is addressed with an in-house test rig and a robust experimental procedure to measure demoulding forces (DF) as well as the final quality of the moulded part between thermoset polymers and moulds. After the characterization of several Sol-Gel coatings formulations (inorganic; hybrid) the influence of several parameters is analysed experimentally, i.e.: Sol-Gel efficiency, texture effects, pattern geometry, roughness and material compound. The results obtained from the experimental studies reveal that texture depth is the most critical geometrical parameter showing high scatter among the selected compounds. Finally, the experimental results are used to compute a model through Reduced Order Modelling (ROM) technique for the prediction of DF.