List of top Materials, Manufacturing & Industrial Engineering Questions on Solidification and cooling asked in GATE ME

Aluminium is casted in a cube-shaped mold having dimensions as 20mm × 20mm × 20mm. Another mold of the same mold material is used to cast a sphere of aluminium having a diameter of 20mm. The pouring temperature for both cases is the same. The ratio of the solidification times of the cube-shaped mold to the spherical mold is ____ (answer in integer).
Consider sand casting of a cube of edge length $a$. A cylindrical riser is placed at the top of the casting. Assume solidification time, $t_s \propto V/A$, where $V$ is the volume and $A$ is the total surface area dissipating heat. If the top of the riser is insulated, which of the following radius/radii of riser is/are acceptable?
A cast product of a particular material has dimensions 75 mm \(\times\) 125 mm \(\times\) 20 mm. The total solidification time for the cast product is found to be 2.0 minutes as calculated using Chvorinov's rule having the index, \(n = 2\). If under the identical casting conditions, the cast product shape is changed to a cylinder having diameter = 50 mm and height = 50 mm, the total solidification time will be \(\underline{\hspace{1cm}}\) minutes (round off to two decimal places).