Prediction of Cure Level in Thick Rubber Cylinder Using Finite Element Analysis

Curing process, or vulcanisation, is essential in the production of rubber components used in most engineering applications. The process inserts chemical bonds between rubber chains to give required mechanical stability as well as improved properties such as elasticity, tensile strength, modulus, and chemical resistance. During the curing process, there is a temperature distribution in thick rubber components as the thermal conductivity of rubber compound is very low. This causes the distribution of cure level from which the performance of such products might be impaired. It is therefore of interest to predict the distribution of cure level in a rubber component using the well-established technique, namely Finite Element Analysis (FEA). Thick cylinder made from natural rubber (NR) was selected for this study. The commercially available FE software (namely NISA II) was employed in association with the specially written software called CURECALC.EXE. To validated FEA prediction, measurement of cure level, determined by crosslink density, at various locations in the cylinder was carried out for comparison purposes. Results indicate that FEA can be used to predict cure level of thick rubber components with acceptable accuracy. The % difference between predicted and experimental values was found to be less than 25%.