EXPERIMENTAL INVESTIGATION OF THE SAND REMOVAL IN WATER-SOLUBLE SAND MOULDS USING WATERJETS

Abstract

Due to the strong competition in the automotive industry, automakers must find innovative ways to manufacture car parts out of low-density materials in order to provide weight reduction and consequently fuel economy for vehicles. The recently invented Ablation Casting technique presents great potential for vehicle light weighting and hence it is gaining momentum in commercial operations. In this technique, a spraying system is used to increase the solidification rate of the casting. The spraying system removes the water-soluble sand mould away and produces extremely high cooling rates by using waterjets directly impinging on the solidifying metal surface. The high cooling rates result in small grain size in the microstructure and consequently enhances the mechanical properties of the casting. Although the spraying system has a profound effect on the process, the effect of waterjet parameters on the removal of the sand mould has never been studied.

The objective of this study is to investigate the use of waterjets in the removal process of water-soluble sand moulds. This study aims to develop a predictive model of the rate of sand removal for a given set of operating conditions of the spraying system. The effect of waterjet parameters on the rate of sand removal is investigated qualitatively within the appropriate range of operating conditions in order to establish an empirical model. These parameters include: standoff distance, waterjet momentum and overlapping percentage of multijets. This model can be implemented and used for different sand and water-soluble binder systems and the time of sand mould removal for given mould thickness can be estimated. Additionally some aspects of the removal mechanism have been discussed.

The results of this study provide an understanding of the interaction between the waterjet parameters and their effect on the rate of sand removal. It was shown that the developed model in this study is able to predict the time of sand removal correctly in casting applications.