In this study, direct observation was employed to experimentally observe the flow pattern for the mold filling. The results
show that an increase in the width of the gate with a constant thickness results in the variation of mold filling, of which three different patterns were observed. They are the narrowing, expansion and deviation of molten metal fronts. It is also evident that the change of the gating system type deviates flow away from the centerline of the mold which leads to a great influence on mold filling pattern. A considerable effect of the geometry of a gate with a constant cross section area on flow pattern has been observed, which primarily results from the change of the metal head pressure at the entrance of the mold.In nonpressurized gating systems, the deviation of melt flow from the centerline of the mold or incomplete gate filling tends
to appear. To avoid the problem of melt flow deviation or incomplete gate filling, a gating system ratio of G: R=1 is
recommended for the design of an effective gating system.