1) A metal is being cast into a cylinder which is 10 cm in diameter and 20 cm tall. The mold is bottom-gated (see class notes for geometry). The vent on this part should be 4 cm high, and does NOT fill with metal. You wish the part to fill in 25 seconds with no aspiration. The metal has a density of 1500 kg/m3 and a viscosity of 1.3x10-3 N-s/m2. The pouring basin is 2 cm tall.
Determine the dimensions of top and bottom of the sprue, and of the runner and gate. The bottom of the sprue, the runner and the gate should have the same diameter.
2)A copper part being cast is a cylinder which is 10 cm in diameter and 20 cm tall. The copper is poured at 45 C above its melting point to assure that it fills the mold before the copper freezes. You have two choices: sand casting (show this is an insulating mold) and permanent mold casting in a gray cast iron mold, with h = 150 W/m2-K (show this is a conducting mold). The molds are at 50 C. Compare the solidification times for both cases.