The effects and role played by additives such as a) sea coal b) silica flour c) cereals and d) iron oxide, in green sand molding.

1)      Sea coal:

a)      It is added to molding sand for cast iron to improve the stripping and surface appearance of cast iron.

b)      The amount of sea coal addition varies from 1% (small castings) to above 10% (for large green sand castings).

c)      Sea coal is finely powdered bituminous coal.

2)      Silica flour

a)      It is pulverized silica which can pass through 200 mesh sieve.

b)      It improves surface finish.

c)      It adds to hot strength.

d)     It resists metal penetration.

e)      It minimizes sand expansion defects.

f)       Silica flour may be added up to 35%.

3)      Cereals / finely ground corn flour

a)      It increases green and dry strength of the molding sand.

b)      It minimizes sand expansion defects.

c)      It improves collapsibility.

d)     Cereals may be added in amount ranging from .25 to 2.0 %. 

4)      Iron oxide:

It develops hot strength.