The document introduces metal forming processes. It defines metal forming as shaping metallic materials through plastic deformation, where the shape changes permanently in contrast to elastic deformation. It describes bulk deformation processes as involving large plastic deformation without changing volume. These include hot working like forging above the recrystallization temperature for easier forming, and cold working like rolling at room temperature for better accuracy. Sheet forming processes change the shape but not the cross-section, operating on thin metal sheets using stamping presses.

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Introduction to Metal Forming Processes
Definition of Metal Forming
 “Metal forming refers to shaping of metallic materials by
means of plastic deformation”.
 The term plastic deformation describes permanent shape
change, in contrast to elastic deformation.
 An elastic deformation disappears when the load is
removed. Many industrial materials are shaped into useful
products by plastic deformation.

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Bulk Deformation and Sheet-Forming Processes
A- Bulk Deformation Processes
 These processes involve large amount of plastic
deformation. The cross-section of workpiece changes
without volume change. The ratio cross-section area/volume
is small.
 For most operations, hot or warm working conditions are
preferred although some operations are carried out at room
temperature.
 Bulk Deformation Processes includes a wide variety of
techniques, which make use of suitable force, pressure or
stresses, like compression, tension and shear or their
combination to cause a permanent deformation of the raw
material to impart required shape.
 These processes are also known as mechanical working
processes and are mainly classified into two major categories
i.e., hot working processes Warm working and cold working
processes.
 In these processes, no material is removed; however it is
deformed and displaced using suitable stresses like
compression, tension, and shear or combined stresses to
cause plastic deformation of the materials to produce required
shapes.

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 Such processes lead to production of directly usable articles
which include kitchen utensils, rods, wires, rails, cold drink
bottle caps, collapsible tubes etc.
 Some of the important metals forming processes are:
Hot working Processes
(1) Forging, (2) Rolling, (3) Hot spinning, (4) Extrusion, (5) Hot
drawing
Cold working processes
(1) Cold forging, (2) Cold rolling, (3) Cold heading, (4) Cold
drawing, (5) Wire drawing,(6) Stretch forming,

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 Cold working is metal forming performed at room
temperature.
 Advantages: better accuracy, better surface finish, high
strength and hardness of the part, no heating is required.
 Disadvantages: higher forces and power, limitations to the
amount of forming, additional annealing for some material is
required, and some material are not capable of cold working.
 Warm working is metal forming at temperatures above the
room temperature but below the recrystallization one.
 Advantages: lower forces and power, more complex part
shapes, no annealing is required.
 Disadvantages: some investment in furnaces is needed.
 Hot working involves deformation of preheated material at
temperatures above the re-crystallization temperature.
 Advantages: big amount of forming is possible, lower forces
and power is required, forming of materials with low ductility,
no work hardening and therefore, no additional annealing is
required.

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 Disadvantages: lower accuracy and surface finish, higher
production cost, and shorter tool life.
Importance of Rolling Example:

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Forging Example:

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B- Sheet-Forming Processes
 In sheet metal working operations, the cross-section of
workpiece does not change—the material is only subjected to
shape changes. The ratio cross-section area/volume is very
high.
 Sheet metal working operations are performed on thin (less
than 6 mm) sheets, strips or coils of metal by means of a set of
tools called punch and die on machine tools called stamping
presses. They are always performed as cold working
operations.
 Sheet metal working processes such as piercing, punching,
lancing, notching, coining, squeezing, deep drawing, bending
etc.

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Characteristics of Metal Forming
Following are some general characteristics of metal forming
processes:
 The work piece is completely or partially subjected to plastic
deformation during the forming operation; that is, it is
plasticized.
 The plastic deformation is most commonly large.
 Little or no material is removed during the forming process.
 The microstructure of the as-cast workpiece is broken down
by the plastic deformation. Therefore, the final component,
or product, made by metal forming usually will have better
mechanical properties than a similar product manufactured
by casting or machining.
 During cold deformation, mechanical properties, such as the
yield strength and tensile strength, will increase because of
the accumulation of plastic strain in the material.

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Animation
Tensile Test (Stress-Strain Diagram)

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Final
Neckin
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Fracture