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Laca, Alexander Arrilaga (2011) Modelling vulcanization and pheological processes during injection moulding of rubber mixes using CAE. Doctoral thesis, London Metropolitan University.
Rubber injection moulding is a well known process for manufacturing a wide range of products. The process comprises two main steps, notably mould filling and curing. Presently there is a growing interest in attempting to produce reliable models for the injection moulding process of rubber mixes; such models would obviate the need for machining intricate moulds and carrying out subsequent injection moulding trials. Furthermore, availability of fabrication models would lead to several significant advantages, such as: accurate predictions of cycle times and pressure decay; define processing settings; and, indicate imminent process defects without having to engage in the inconvenience and expense of repeated mould modifications largely based on trial and error.
Although there are a few simulation tools available for modelling the injection-moulding process, it is generally felt however that comparatively little work has been carried out in this area thus far. For instance, some studies include simulations carried with individually developed mathematical codes instead of using commercial ones. The general aim of this project is to develop and define a methodology for performing CAE simulations of the rubber injection moulding process, using Moldflow and Cadmould packages. The intention is that this methodology will cover the entire range of processing stages commencing with the raw material's characterisation (rheology, thermal and cure properties) and ending with the evaluation of the results obtained from the moulded rubber compounds.
In the present work, studies were carried out using two peroxide-cured formulations (based on NBR and EPDM) and a spiral shape mould cavity of constant cross section. The overall primary objective of the present investigation was to attempt to develop a methodology by which more accurate results could be obtained than hitherto using material characterisation and mathematical model definition criteria. Simulation results for the mould filling stages generally showed poor agreement with actual experimental data; nevertheless, prediction of the cure kinetics was reasonable.
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