Forging

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Forgingforging process

• Forging is manufacturing process where metal is
  pressed, pounded or squeezed under great pressure
  into high strength parts known as forgings.
•  

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The forging process

• Heated metal to be shaped is placed on a mold.
  Pressure is applied to the metal with the help of
  a press or hammer and due to this impact the
  malleable metal conforms to the
• die cavity shape.

• Extreme pressure is produced when the die
  halves are closed. The seam of the die as well as
  punch acts as a relief valve. Once the metal
  object is shaped, flashing is removed

• Use of a proper lubricant during the process
  helps to prevent sticking of the workpiece with
  the die. It also acts as a thermal insulator and
  helps the wear and tear on the die

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• Advantages of Forging
•            The forgings are consistent in shape
  and do not have any voids, porosity, inclusions,
  or defects.
• This is especially helpful in later finishing and
  coating operations as surface preparation is
  minimized.
•            Parts that are produced by this
  method have high strength to weight ratio and
  therefore used in the design of the aircraft
  frames.
•            It offers low cost for moderate to
  long runs.

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Different types of Forging processes

• Open Die Forgings or Hand forgings
  In this process the forgings are made with the
  help of repeated blows in an open die. Here the
  operator manipulates the work piece in the die
  during the blow process, similar to the
  traditional manufacturing process used by a
  blacksmith.

  Impression Die Forgings or Precision Forgings
These forgings are the refined form
of blocker forgings. The finished metal part much
more identical to the die impression.

• Upset Forgings These forgings
  increase the cross-section by reducing the length
  of the metal. The process is used to make heads
  on valves, bolts and fasteners, and other similar
  parts.

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Specifications
The process is used on metals with good ductility
such as copper, aluminum, nickel, steel, and
magnesium. Minimizing size, material volume, and
complexity of the design can reduce cost.
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Example parts Connecting rods, crankshafts,
wrenches, hooks etc.

• Forging Design Guidelines
• Avoid undercuts.
• Recommended external draft 6 degrees (96).
• Recommended internal draft 8-10 degrees
  (98-100).
• Provide generous fillet and corner radii to aid
  material flow.
• Provide support webs and ribs.

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Once we receives a blueprint, we proceed to make
the master die. A plaster cast is made from the
master die for approval. After the plaster cast
has been approved, the forging dies are made,
using the master die as a pattern
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• Bar stock is ordered for the manufacture of the
  forgings. The completed forging dies are then
  mounted in a hammer of sufficient size to form
  the forgings.
• The bar stock is cut into lengths appropriate to
  the dimensions of the finished forging.The
  lengths of material are heated in a forging
  furnace

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Each length is pulled from the forging furnace by
the hammerman using tongs, and placed in the
blocker area of the forging die. The hammer is
activated for several blows
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• Then, the rough formed forging is moved to the
  finisher area of the forging die. The hammer is
  activated once again for several blows.
• At this point, the forging is fully formed, but,
  still has a flash attached to it. The flash is
  the excess material around the formed forging.

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• The forged piece is removed from the forging
  dies by a trimmerman and is placed in a trim
  press. A few blows are necessary to remove the
  flash from the forging

• The completed forging is then placed in a
  cooling bin. The cooling bin may contain liquid,
  to comply with the specifications provided on the
  blueprint supplied.

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• Once cooled, the forgings are placed in a
  wheelabrator with fine steel shot to clean off
  scale and discoloration formed in the forging
  process

A Forged metal can result in the following

• Increase length, decrease cross-section, called
  drawing out the metal.

• Decrease length, increase cross-section, called
  upsetting the metal

• Change length, change cross-section, by
  squeezing in closed impression dies. This results
  in favorable grain flow for strong parts

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Cold Forging is a cold working process where the
material is squeezed into a die and the finished
parts assume the shape of the die. This process
is also known as Cold Heading. Bar stock or
wire stock is fed into a die and is squeezed into
the closed die. The resultant part is a nail, a
bolt or a screw with the head. A subsequent
cold heading operation forms other features on
the head such as knurls or slots for screw
drivers etc. the shaping rod stock by forming the
head as in rivets, bolts, nails and other
fasteners. This process can be highly automated
and parts can be made economically.
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