Hydraulics, Dimensional Analysis and Visualization of Flow through Unpressurized Gating Systems Using Water Models

Abstract

During recent years, foundry industry has witnessed an increasing awareness about the importance of the filling stage for the production of metallurgically sound and dimensionally stable castings. The metallurgical soundness of a casting is strongly influenced by the way the liquid metal flows through various parts of the gating system and fills the mould cavity. Owing to the importance of filling stage, extensive research has been directed towards the determination of optimum filling conditions as well as on the influence of gating parameters. In this study, the hydraulics and flow behaviour of an aluminium alloy in a pressurized, horizontal gating system with a gating ratio of 1 : 2 : 1 incorporating multiple ingates attached to a horizontally cast plate mould is investigated using transparent water models. Similitude considerations between water and aluminium were invoked in the design of water models so that the conclusions drawn from water model experiments become applicable to real casting. Runners with two different aspect ratios and four different types of ingates were examined for their influence on hydraulics and flow behaviour. Flow behaviour was visualized using a high speed camera capable of capturing images up to 10,000 frames per second. Comparison of the filling patterns between water model experiments and real time experiments with molten metal in sand moulds provided useful insights into the performance of pressurized, horizontal gating system with multiple ingates and on the utility of flow visualization using water models.