Geometrical effects on filling dynamics in low pressure casting of light alloys

Abstract

In aluminum low-pressure sand casting process, filling oscillations are observed when the metal front reaches a section change in a part. The effect of geometry on the filling oscillations is primary considered experimentally, including both mold cavity and filling system geometries. To highlight the geometric parameters impacting the oscillations, the pressurized melt flow is secondly studied numerically and analytically. A new analytical model of oscillation is developed to quantitatively predict the oscillations. It links the resulting filling velocity to both the low-pressure casting parameters and the mold cavity geometry. Considering oxides inclusion criterion from casting literature, new rules to avoid bi-films defects are recommended for making reliable low-pressure castings.