A sand mold has a top sprue of length = 100 mm , and the pouring basin has a height of 30 mm . The velocity at the top of the pouring basin is relatively small and can be considered 0. The diameter at the bottom of the sprue is 15 mm . The sprue leads into a horizontal runner on the parting plane that feeds the molten metal to the mold cavity prepared by the single pattern as shown below. The liquid metal is Aluminum whose density is ? =2750 kg/m 3 , and dynamic viscosity ( at T pour ): h =4x10 -3 Pa.s : Sketch the sprue in cope and the pattern with its proper orientation and position in the drag part of the mold. Indicate the surface of pattern which is on parting line or parting plane.   (4 points) The velocity ( m/s ) of the molten metal flowing through the base of the sprue.         (2 points) The volume rate of flow ( m 3 /s ) of the molten metal.                                                  (3 points) The time ( seconds ) required to fill the mold cavity.                                                   (4 points) If the sprue is designed such that there is no aspiration then what will be the diameter at the top of the sprue ( i.e., bottom of the pouring basin) (4 points) Calculate the upward force (buoyancy) acting on the cope when the molten metal fills the mold cavity. (4 points) Determine the Reynolds\'s Number at the bottom of sprue. Comment on the answer.                                                                                                                                                          (4 points) 20mm 75mm 50mm 5 igure 1 Solution .

1. A sand mold has a top sprue of length = 100 mm , and the pouring basin has a height of 30 mm .
The velocity at the top of the pouring basin is relatively small and can be considered 0. The
diameter at the bottom of the sprue is 15 mm . The sprue leads into a horizontal runner on the
parting plane that feeds the molten metal to the mold cavity prepared by the single pattern as
shown below. The liquid metal is Aluminum whose density is ? =2750 kg/m 3 , and dynamic
viscosity ( at T pour ): h =4x10 -3 Pa.s :
Sketch the sprue in cope and the pattern with its proper orientation and position in the drag part
of the mold. Indicate the surface of pattern which is on parting line or parting plane. (4 points)
The velocity ( m/s ) of the molten metal flowing through the base of the sprue. (2 points)
The volume rate of flow ( m 3
/s ) of the molten metal. (3 points)
The time ( seconds ) required to fill the mold cavity. (4 points)
If the sprue is designed such that there is no aspiration then what will be the diameter at the top
of the sprue ( i.e., bottom of the pouring basin) (4 points)
Calculate the upward force (buoyancy) acting on the cope when the molten metal fills the mold
cavity. (4 points)
Determine the Reynolds's Number at the bottom of sprue. Comment on the
answer.
(4 points)
20mm 75mm 50mm 5 igure 1
Solution