What is the important about grain fineness number for sand casting?

Answer 1

gfn shows the range of the sand size. as we know sand are differ in shapes and sizes. if the gfn is between 40 and 100 it can be classified as coarse and 100-220 is fine. typically for ferrous casting the gfn is 70 but it can be range between 50 to 100. it is because if the gfn is below 50 it will result poor surface quality. if the gfn above 100, its too fine and gives low permeability and might be defects occur due to the large surface area

Answer 2

Grain fineness number (GFN) is important for sand casting as it indicates the size of sand grains used in the molding process. A lower GFN indicates finer sand grains which can result in smoother cast surfaces and better dimensional accuracy. Controlling GFN helps to achieve desired casting quality and reduce defects such as rough surfaces or metal penetration.