Mold and mold making

Mold:

1)      Prepared molding sand is packed rigidly around the pattern and when the pattern is withdrawn, a cavity corresponding to the shape of the pattern remains in the sand and is known as (molder) mold cavity.

2)      Thus mold is a sort of container which when poured with molten metal produces a casting of the shape of the mold.

3)      The process of making mold is referred to as mold making.

Mold characteristics:

A mold must:

1)      Possess refractoriness to bear the high heat of the molten metal.

2)      Possess strength to hold the weight of molten metal.

3)      Produce a minimum amount of mold gases.

4)      Be able to resist the erosion action of the molten metal being poured.

5)      Resist metal penetration into the mold walls.

Mold types:

a)      Green sand mold

b)      Dry sand mold

c)      Skin dried mold

d)     Air dried mold

e)      Core sand mold

f)       Loam mold

g)      Shell mold

h)      Cement bonded sand mold

i)        Metal mold or dies

j)        Investment mold

k)      Ceramic mold

l)        Plaster mold

m)    Graphite mold

n)      Sodium silicate –CO2 mold

Molding methods:

a)      Bench molding

b)      Floor molding

c)      Pit molding

d)     Machine molding

1)      Jolt machine

2)      Squeezer machine

3)      Jolt-squeezer machine

4)      Sand slinger