Bentonite is commonly used bonding material for dry sand cores

According to Chvorinove's rule, the solidification time of a casting is proportional to [Volume/Surface area]ⁿ where $$n=....$$

A cylinder of $$150mm$$ diameter & $$200mm$$ height is to be cast with out any riser. The cylinder is moulded entirely in the drag of a green sand flask & is top gated. The cope of the flask is $$200mm$$ height & the height of the metal during pouring is $$50mm$$ above the cope. A tapered sprue is employed & the gating ratio is $$1:1.5:2$$. The time taken (in seconds) to fill the casting cavity neglecting energy losses, if the in-gate area is $$400sq.mm$$

If for a matrix, rank equals both the number of rows and number of columns, then the matrix is called