Three castings are of the same material, volume and cast under similar conditions. One is a sphere, another is a cube and the third is cylinder with its length being equal to its diameter.

The ratio of solidification times of sphere to the cube is

Three castings are of the same material, volume and cast under similar conditions. One is a sphere, another is a cube and the third is cylinder with its length being equal to its diameter.

The solidification time of the sphere to the cylinder

A rectangular block of steel $$C.S$$ $$100\,\, \times \,\,150mm$$ and $$250mm$$ height is to be cast with out any riser. The block is moulded entirely in the drag of a green sand flask & is tap gated. The cope of the flask is $$200mm$$ height & the height of the metal during pouring is $$100mm$$ above the cope level. A tapered sprue is employed & the gating ratio is $$1:4:2$$. Assume no energy losses in the system. The time taken (in seconds) to fill the casting cavity, if the tapered sprues with $$500$$ $$m{m^2}$$ exit area is used.

A steel plate $$40cm \times 30cm \times 0.3cm$$ is to be cast. The volume shrinkage of steel during solidification is $$3\% .$$ A cylindrical side riser with diameter $$4cm$$ and height $$4cm$$ is used. The riser volume should at least be $$3$$ times that the dictated by shrinkage consideration. Is the riser volume sufficient if not what is the riser size?