A given material
(shapeless or a simple geometry)
Primary shaping processes
Metal forming processes
A complex geometry
(shape, size, accuracy,
tolerances, appearance,
Properties)
Casting, melt extrusion, die casting, etc.
Rolling, extrusion, forging, bending, drawing
(plastic deformation)
Metal cutting processes
Sawing, turning, milling
(by removing metal)
Metal treatment processes
Heat treatment, surface hardening
(unchanged in shape, changed in properties)
Joining processes
Metallurgical joining : welding,
Mechanical joining : riveting, shrink fitting, assembly
Material type
Massive forming processes (Bulk forming processes)
: forging, extrusion, rolling, drawing
•Large plastic deformation, appreciable change in shape or cross section,
•The portion of permanent deformation >> elastic deformation
•Elastic deformation is negligible
Sheet forming processes
: deep drawing, stretch forming, press forming
•Sheet, changes in shape, not in section, permanent=elastic, e/recovery
Forming temp.
Cold forming processes : room temperature
Hot forming processes : above the recrystallization temp.
☞ Most materials behave differently under different temperature condition
; [cold forming] Y.S. increases with an increase of strain
; [hot forming ] Y.S. increases with an increase of strain rate
Attractive points
☞ in case where the part geometry is of moderate complexity
☞ in case where the production volume are large
☞ in case where tooling costs per unit product should be kept low
Billet material
Flow stress as a function of strain, strain rate, temperature,
microstructure (constitutive equation)
Workability as a function of strain, strain rate, etc
(forming limit diagram)
Surface condition
Mechanical properties (thermal/physical)
Tooling
Geometry of tools
Surface condition
Heat treatment / hardness



  f   ,  , T 


Accuracy / tolerances
Interfacial
condition
Lubricant type and condition
Cooling characteristics of the interface layer
Friction
  P  mk
k

3
Deformation
zone
Deformation mechanics / model used for analysis
Metal flow and velocity
Stresses (variation during deformation)
Temperatures (heat generation and transfer)
Equipment
Speed / Production rate
Force / Energy capabilities
Rigidity and accuracy
Product &
Environment
Dimensional accuracy
Surface finish
Plant and production facilities and control
Closed die forging with flash
☞ a billet is formed (usually hot) in dies (usually with two halves)
☞ the excess of the material is extruded through a restrictive narrow gap
Closed die forging without flash
☞ in this process, a billet with carefully controlled is deformed by a punch
☞ in order to fill a die cavity without any loss of material, the punch and
the die may be made of one or several pieces
Coining process
☞ coining is a closed die forging (usually called restriking)
☞ all surfaces of the work are confined or restricted
☞ resulting in well-defined imprint of the die on the workpiece
☞ A punch compresses a billet (hot or cold) confined in a container
☞ the billet material flows through a die in the same direction as the punch
☞ a moving punch applies a steady pressure to a slug confined in a closed die
☞ it forces the metal to flow around the punch in a direction
opposite the punch direction
☞ Open die forging is a hot forming process
☞ the metal is shaped by hammering or pressing between flat or simple
contoured dies.
☞ most of shafts can be manufactured by this process
☞ orbital forging shapes parts by incrementally forging a slug between
an rotating upper die and a non-rotating lower die
☞ the lower die is raised axially toward the upper die, which is fixed axially
☞ Through the upsetting process, the cross sectional area in increased
☞ a hot or cold forming process for reducing the cross-sectional area
☞ this process uses rotating rolls
☞ the rolled material (plate) elongates and spreads at the same time
☞ Shape rolling is a cold or hot forming process for reducing as well as
shaping the cross section of the metal
☞ the metal passes through a series of rotating sets of rolls with grooves
☞ the process of reducing the cross section and the diameter of a tube
☞ a process where a hollow circular blank is formed into a ring
☞ a main roll presses on the outside diameter of the blank
☞ shaped cross section is obtained by contouring of the mandrel and the roll
☞ a process for hot or cold seamless shaping of dished part
☞ it uses the combined forces of rotating and pressure
☞ drawing is the process of reducing the cross-sectional area and the shape
of a rod, bar, tube or wire by pulling through a die
☞ a sheet blank is forced by a punch into a die to form a deep recessed part
☞ this process is used to produce cylindrical cup shape
☞ an internal pressure is applied so as to form a tube to the desired shape
☞ the internal pressure can be delivered by expanding a punch through
a fluid
☞ roll bending gives a curvature to a sheet, bar or shaped section by bending it
between two or three cylindrical rolls