Characterisation of the decoring behaviour of inorganically bound cast-in sand cores for light metal casting

Abstract

This article proposes a new method to classify the decoring behaviour of different cast-in sand cores for light metal casting. Sand cores are in use to realise hollow structures in casting parts. More and more inorganically bound sand cores are used due to environmental requirements, which, in contrast to organically bound sand cores, do not disintegrate during the casting process. The inorganically bound cast-in sand cores need to be removed after the casting process by a process called decoring. A test rig derived from the industrial decoring process was built to investigate the decoring behaviour and to measure the effort of decoring. The proposed method is based on single impulses imposed on the test geometry. The goal of this approach is to understand the factors influencing the decoring behaviour of a sand core. Therefore, different sand-binder systems, with varying amounts of binder and different grain size distributions, were decored and examined with the developed test rig. A validation of the experimental results using simulation methods showed a high influence of the residual compression strength of the sand cores to their decoring behaviour. The authors showed that specimens with a higher amount of residual compression strength are more difficult to decore than specimens with a lower amount of residual compression strength. The methods and results presented in this article build the foundation to model a digital twin of the decoring process which is a missing link in the digital process chain in casting technologies.