Question

A mold has a downsprue length = 6.0 in. The cross sectional area at the bottom of the sprue is 0.5 in2. The sprue leads into a horizontal runner which feeds the mold cavity, whose volume = 75 in3. Determine (a) velocity of the molten metal flowing through the base of the downsprue, (b) volume rate of flow, and (c) time required to fill the mold cavity.

Answer 1

a) To calculate the velocity of the molten metal we need to apply the conservative energy equation,

$V=\sqrt{2gl}V=\sqrt{2(32.2)(\frac{6}{12})}$

*Note I am converting all to feet.

$V=6.6745ft/s$

b)To calculate the volume flow we only use the equation of Discharge, so

$Q=AV\\Q=(\frac{0.5}{12^2})(5.6745)\\Q=0.0197ft^3/s$

c) To calculate the time we use the equation of Discharge but in terms of Velocity, that is,

$t=\frac{\dot{V}}{Q} \\t=\frac{75/12^3}{0.0197}\\t=2.20s$