Jan 01, 2021 · The grain fineness number (GFN) is expressed as: (1) GFN = ∑ M n f n ∑ f n. Where,M n = multiplying factor of the nth sievef n = percentage of sand remains on the n th sieve. 3.2. Mold and its characterization. The Co 2 molding isCustom to make the mold of industrial