Sand molding is a process of making sand mould
with the help of pattern. The mould cavity of
required shape and size is formed in sand by
using pattern of same size and shape. This
cavity is known as sand mould. Molten metal is
poured in this mould and allowed to solidify.
After solidification, casting is removed by
generally destroying the sand mould. The sand
mould can be classified as.
Green sand moulds (ii). Skin-dry moulds (iii). Dry sand moulds
Sand molding methods:
Bench molding –
It is used for relatively small
moulds. The mould is prepared on a conventional bench. Any kind of sand
moulds can be made by this method. The various bench molding methods are
– Two boxes known as cope (upper) and drag (lower) are used to make sand
mould. These are fitted with suitable clamping and locating device.
– In flange type pattern, a third box known as ‘cheek’ is used to
facilitate the molding work. All the three boxes are clamped properly
during pouring the metal.
– It is used when a number of small castings, each having one flat
surface, are to be made. A common passage is there for all moulds to
pour the molten metal.
– It is used to make medium and large
moulds. Generally two boxes (cope and drag) are used to make a mould. It
can be used to make any kind of sand mould. It is a very slow and
Pit molding – When the size of pattern for mould is
very large to be handled in flasks, pit molding is used. Pit acts as a
drag part of flask and a separate cope is used above it. Generally green
sand is used in pit molding. This method is quite slow and laborious.
Machine molding – This method can be used for any size and
kind of sand moulds. It is a very fast method which uses machine to make
sand moulds but it requires mounted patterns.