A riser in the shape of a sphere is to be designed for a sand casting mold. The casting is a rectangular plate, with length = 300 mm, width= 150 mm, and thickness 20 mm. If the total solidification time of the casting itself is known to be 4.0 min: 1. Determine the diameter of the riser so that it will take 30% longer for the riser to solidify. 2. Discuss, why the riser should take longer to solidify compared to the cast itself. Pouring cup Cast metal in cavity Riser Cope Downsprue- - Parting line Runner Flask Drag Mold