Abstract
It has been shown that passing of air through molten metal can have a great contribution to the formation of oxide defects in casting of aluminium alloys. In gravity casting of these alloys, the design of gating system has a considerable effect on the formation of air bubbles and their behaviour afterwards. This paper is aimed to study the effect of pouring basin and sprue design on the quantity of air bubbles entering the mould cavity. In order to do this, water modelling of pouring into several gating systems varying in pouring basin and sprue design was conducted, and quantified results were used to compare the designs in terms of the ability to prevent bubble formation and entrainment. It was concluded that the offset basin with a 1 in. high barrier in bottom is the most efficient design in preventing bubble entrainment.