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# GATE Mechanical 1993 Question

An aluminium cube of $10$ $cm$ side has to be cast along with a cylindrical riser of height equal to its diameter. The riser is not insulated on any surface. If the volume shrinkage of aluminium during solidification is $6\%$, calculate shrinkage volume of cube on solidification and minimum size of the riser so that it can provide the shrinkage volume.

# GATE Mechanical 1996 Question

The pouring basin in a sand mold is $200$ $mm$ diameter $100$ $mm$ height. The mould cavity is a cube of $125$ $mm$ side and must be filled in $25$ seconds. The maximum velocity must ensure laminar flow into the mould cavity and in the gates of circular cross-section. Design the sprue to avoid aspiration effects.

Assume
(a) constant temperature,
(b) no loss in the velocity head and
(c) diameter of gate $=8$ times diameter at the sprue base.

Properties of the molten metal are $\gamma = 0.9\,\,m{m^2}$ per second, $\rho = 700\,\,kg/{m^3},$ & ${C_p} = 33.6\,\,J/mol$-$K.$ The diameter of sprue to avoid aspiration effect.

# GATE Mechanical 1999 Question

In a particular mold design, the down sprue has an area of Cross section of $6.45\,\,c{m^2}$ where the pouring basin leads into the sprue. The sprue is $20$ $cm$ long. The required metal flow rate at the top section of the sprue is $820$ $c{m^3}/s.$ Determine the pouring height necessary above the sprue top. Also determine the area of $C.S$ of sprue at its bottom to avoid the aspiration of liquid molten metal.