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MANUFACTURING
PROCESS > FORGING
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The
Forging Process is the forming of linear bars of metal
into desired 3-dimensional shapes. This metal forming
is done by way of applying a very high amount of pressure
on the steel bars. The main equipment used for this
purpose is a forging press and the forging dies made
from a special alloy steel with a very high tensile
strength. The forging process can be divided into the
following operational stages:
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Die
Design & Development:
After the receipt of the finished part drawings from
the customers, the engineering teams at the forging
facilities develop a forging drawing from the finished
part drawing. Then they develop a 3-dimensional model
for the part to be forged. From this 3-dimensional model,
the engineers then create the 3-dimensional models of
the forging dies, trimming dies and the coining dies;
which comprise a complete set of dies for a particular
part. The final process in this stage is the die-sinking
operation, wherein the actual shape of the part is replicated
on the die-blocks in form of cavities.
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Inspection Of Dies: The
set of dies manufactures is then subjected to a series
of tests for verifying the accuracy of the design &
shape of the cavities on them. For this purpose, plaster
of Paris is poured into the die blocks and is allowed
to set. Then the plaster cast is then removed from the
die cavity and subjected to dimensional verification
by the quality assurance team. Once the quality assurance
team is satisfied with the dimensional accuracy, they
approve the die set to be issued to the production department
for loading on the forging presses.
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Forging: The set of die blocks thus manufactured
is loaded on to the forging press, trimming press and
the coining press. Then simultaneously another process
involves cutting of steel pieces from straight steel
bars known as billets. These billets are then heated
to a definite temperature by electrical energy known
as induction billet heating. The heating time and the
flow of current are regulated to control the billet
at a desired temperature. The red-hot billets are given
an approximate shape by a process called reduce-rolling.
Then these red hot billets are placed in the cavity
of the die block in the forging press where the billet
under the impact / pressure of the press stroke takes
the final desired shape. The red hot forging is then
placed onto the next station known as trimming press
to remove extra material called flash. The forging is
then allowed to cool down. It is inspected for its dimensional
accuracy.
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Heat Treatment: Once approved for its accuracy,
these forgings are then subjected to a process of hardening
and/or tempering depending on the hardness requirement
of the component. This hardening & tempering is
done by subjecting the forgings to a controlled heating
inside specially designed automatic heating furnaces.
This process is required because a lot of stresses develop
in the steel because of induction billet heating and
forging. These effects of these stresses are removed
by proper hardening and tempering in automatic heat
treatment systems.
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Shot-Blasting: After hardening & tempering,
the surface of the forgings is oxidized by scale formation.
These scales are then removed by a process called shot-blasting.
This process involves striking the surface of the forgings
by tiny spherical particles of sand and metal to remove
the scales. This process of shot-blasting also makes
the surface of the forging clean and gives it silvery
appearance.
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