In order to investigate the flow of molten metal in a cavity of a die, experimental simulation was carried out by using water flow model. The experimental cavity was constructed of a backward step configuration for test zone, in which flow behavior and air exhaust process from the cavity were investigated. With rib material installed down the step, its effect on air exhaust promotion was examined for various flow velocities. The main results obtained are as follows : Air exhaust from the cavity is remarkably promoted by installation of rib because the strong turbulence around the rejoining potion of two different flows, which are separated by the rib at the upstream, broke rapidly the trapped air into small bubbles. The time taken to complete air exhaust process is in inverse proportion to the flow velocity in the high velocity region, while it is proportion to the flow velocity to the -2.27th power in the low velocity region.
