Metal forming processes include bulk deformation processes that significantly change the shape of metal parts through plastic deformation. The four main bulk deformation processes are rolling, forging, extrusion, and wire/bar drawing. Rolling involves passing metal between opposing rolls to reduce thickness or change cross-section. Forging involves compressing metal between dies to shape it. Extrusion uses a die to shape metal as it is squeezed through the die opening. Wire/bar drawing reduces diameter by pulling metal through a die. These processes are important for net-shape forming with little waste.

1. METAL FORMING PROCESS
(DEFORMATION PROCESSES)
WP 1st Semester IED

2. 2

3. Bulk Deformation Processes
3

4. Bulk Deformation
• Metal forming operations which cause significant shape
change by deforming metal parts whose initial form is bulk
rather than sheet
• These processes stressmetal sufficiently to cause plastic flow
into desired shape
• Performed as cold, warm, and hot working operations
4

5. Importance of Bulk Deformation
• In hot working, significant shape change can be
accomplished
• In cold working, strength is increased during shape
change
• Little or no waste - some operations are near net
shape or net shape processes
– The parts require little or no subsequent machining
5

6. Four Basic Bulk Deformation Processes
1. Rolling – slab or plate is squeezed between opposing
rolls
2. Forging – work is squeezed and shaped between
opposing dies
3. Extrusion – work is squeezed through a die opening,
thereby taking the shape of the opening
4. Wire and bar drawing – diameter of wire or bar is
reduced by pulling it through a die opening
6

7. • Rolling operations reduce the thickness or change
the cross section of a material through compressive
forces
• Often the first process that is used to convert
materialinto a finished wrought product
• Thick stock can be rolled into blooms, billets, or slabs
Rolling
7

8. Types of Rolling
• Based on workpiece geometry :
– Flat rolling - used to reduce thickness of a rectangular
cross section
– Shape rolling - square cross section is formed into a
shape such as an I-beam
• Based on work temperature :
– Hot Rolling – most common due to the large amount of
deformation required
– Cold rolling – produces finished sheet and plate stock
8

9. Flat Rolling
• Rotating rolls perform two main functions:
– Pull the work into the gap between them by friction
between workpart and rolls
– Simultaneouslysqueeze the work to reduce its cross
section
9
Figure- The rolling process (flat rolling).

10. Shape Rolling
• Work is deformed into a contoured cross section
rather than flat (rectangular)
• Accomplished by passing work through rolls that
have the reverse of desired shape
• Products include:
– Construction shapes such as I-beams, L-beams, and U-channels
– Rails for railroad tracks
– Round and square bars and rods
10

11. Shape Rolling
11
Figure- Stages in shape rolling of an H-section part.
Various other structural sections are also rolled by this kind
of process.
Straight and long structural
shapes, such as solid bars,
channels, I-beams, and
railroad rails, are rolled by
passing the stock through a
set of specially designed rolls

12. Figure-Some of the steel products made in a rolling mill.
Rolled Products Made of Steel
12

13. Flat-Rolling and
Shape-Rolling
Processes
Figure- Schematic
outlineof various flat-
rollingand shape-rolling
processes. Source: After
the American Iron and
Steel Institute.
13

14. Figure- Side view of flat rolling, indicating before and after thicknesses, work
velocities, angle of contact with rolls, and other features.
Diagram of Flat Rolling
14

15. Flat Rolling Terminology
Draft = amount of thickness reduction
fo ttd
where
d = draft;
to = starting thickness; and
tf = final thickness
15

16. Flat Rolling Terminology
Reduction = draft expressed as a fraction of
starting stock thickness:
ot
d
r
where r = reduction
16

17. Basic Rolling Process
• Metalis passed between
two rolls that rotate in
opposite directions
• Friction acts to propel the
materialforward
• Metalis squeezed and
elongates to compensate
for the decrease in cross-
sectional area
Figure- Schematic representation of the hot-
rolling process, showing the deformation and
recrystallization of the metal being rolled.
17

18. Figure- A rolling mill for hot
flat rolling. The steel
plate is seen as the
glowing strip in lower
left corner
18

19. Rolling Mills
• Equipment is massive and expensive
• Rolling mill configurations:
– Two-high – two opposing rolls
– Three-high – work passes through rolls in both directions
– Four-high – backing rolls support smaller work rolls
– Cluster mill – multiple backing rolls on smaller rolls
– Tandem rolling mill – sequence of two-high mills
19

20. Figure- Various configurations of rolling mills: (a) 2-high rolling mill
(non-reversing).
Two-High Rolling Mill
20

21. Figure-Various configurations of rolling mills: (b) 3-high rolling mill.
Three-High Rolling Mill
21

22. Figure-Various configurations of rolling mills: (c) four-high rolling mill.
Four-High Rolling Mill
22

23. Multiple backing rolls allow even smaller roll diameters
Figure- Various configurations of rolling mills: (d) cluster mill
Cluster Mill
23

24. • Smaller diameter rolls produce less length of contact for a
given reduction and require less force to produce a given
change in shape
Figure- The effect of roll diameter on length of contact for a
given reduction.
24

25. A series of rolling stands in sequence
Figure- Various configurations of rolling mills: (e)
tandem rolling mill.
Tandem (Continuous)
Rolling Mill
25

26. The Rolls
• Roll material must have strengthand wear resistance
• Common roll materials: cast iron, cast steel, forged steel
• Tungstencarbide for small-diameter rolls
• Forged steelrolls are more costly but have greater strength,
stiffnessand toughness than cast iron rolls
• Rolls are ground to a fine finish; for special applications they
are polished
• Rolls made for cold rolling should not be used for hot rolling
because they may crack from thermal cycling
28

27. Thread Rolling
• Bulk deformation process used to form threads on
cylindrical parts by rolling them between two dies
• Important commercial process for mass producing bolts
and screws
• Performed by cold working in thread rolling machines
• Advantages over thread cutting (machining):
– Higher production rates
– Better material utilization
– Stronger threads and better fatigue resistance due to work hardening
29

28. Figure- Thread rolling with flat dies: (1) start of cycle, and (2) end of
cycle.
Thread Rolling
30

29. Ring Rolling
• Deformation process in which a thick-walled ring of smaller
diameter is rolled into a thin-walled ring of larger diameter
• As thick-walled ring is compressed, deformed metal elongates,
causing diameter of ring to be enlarged
• Hot working process for large rings and cold working process for
smaller rings
• Applications: ball and roller bearing races, steel tires for railroad
wheels, and rings for pipes, pressure vessels, and rotating
machinery
• Advantages: material savings, ideal grain orientation, strengthening
through cold working 31

30. Figure- Ring rolling used to reduce the wall thickness and increase the
diameter of a ring: (1) start, and (2) completion of process.
Ring Rolling
32

31. Rotary Tube Piercing
Figure- the rotary tube-piercing process for making seamless pipe and tubing.
33

32. Forging
• Deformation process in which work is compressed between two
dies
• Oldest of the metal forming operations, dating from about 5000 B C
• Metal flow and grain structure can be controlled, so forged parts
have good strength and toughness
• They can be used for highly stressed and critical applications
• Components: engine crankshafts, connecting rods, gears, aircraft
structural components, jet engine turbine parts
• Also, basic metals industries use forging to establish basic form of
large parts that are subsequently machined to final shape and size 34

33. Microstructureas a Function of Manufacturing
Method
Figure- Schematic illustration of a part made by three different processes showing grain flow. (a)
Casting, (b) Machining form a blank, and (c) forging. Each process has its own advantages and
limitations regarding external and internal characteristics, material properties, dimensional accuracy,
surface finish, and the economics of production. Source: Courtesy of Forging IndustryAssociation.
35

34. Classification of Forging Operations
• Cold vs. hot forging:
– Hot or warm forging – most common, due to the
significant deformation and the need to reduce strength
and increase ductility of work metal
– Cold forging – advantage: increased strengththat results
from strain hardening
• Impact vs. press forging:
– Forge hammer - applies an impact load
– Forge press - applies gradual pressure
36

35. Types of Forging Dies
• Open-die forging - work is compressed between two
flat dies, allowing metal to flow laterally with
minimum constraint
• Impression-die forging - die contains cavity or
impression that is imparted to workpart
– Metal flow is constrained so that flash is created
• Flashless forging - workpart is completely
constrained in die
– No excess flash is created
37

36. Figure-Three types of forging: (a) open-die forging.
Open-DieForging
38

37. Figure-Three types of forging: (b) impression-die forging.
Impression-DieForging
39

38. Figure-Three types of forging (c) flashless forging.
Flashless Forging
40

39. Open-Die Forging
• Compressionof workpart between two flat dies
• Same type of forging done by a blacksmith but mechanical
equipment performs the operation
• Simplest industrial hammer is a gravity drop machine
• Open-die forging produces rough forms, and subsequent
operations are required to get final geometry and dimensions
– Deformationoperation reduces height and increases diameter of work
– Commonnames include upsetting or upsetforging
41

40. Figure- Homogeneous deformation of a cylindrical workpart under ideal
conditions in an open-die forging operation: (1) start of process with
workpiece at its original length and diameter, (2) partial
compression, and (3) final size.
Open-DieForging with No Friction
42

41. Figure- Actual deformation of a cylindrical workpart in open-die forging,
showing pronounced barreling: (1) start of process, (2) partial
deformation, and (3) final shape.
Open-DieForging with Friction
43

42. Figure-(Top) Illustration
of the unrestrained flow of
material in open-die
forging.
(Middle) Open-die forging
of a multidiameter shaft.
(Bottom) Forging of a
seamless ring by the
open-die method.
(Courtesy of Forging
Industry Association,
Cleveland, OH.)
44

43. Figure- Several open-die forging operations: (a) fullering, (b) edging, (c) cogging.
Open-DieForging Practice
45

44. Impression-Die Forging
• Compressionof workpart by dies with inverse of desired part
shape
• Some times called closed-die forging
• Flash is formed by metal that flows beyond die cavity into
small gap between die plates
• Flash must be later trimmed, but it serves an important
function during compression:
– As flash forms, friction resists continued metal flow into gap,
constraining material to fill die cavity
– In hot forging, metal flow is further restricted by cooling against
die plates 46

45. Figure- Sequence in impression-die forging: (1) just prior to initial
contact with raw workpiece, (2) partial compression, and (3) final
die closure, causing flash to form in gap between die plates.
Impression-DieForging
47

46. Impression-Die Forging
48
Figure- Terminology for a conventional impression-diein forging

47. Impression-DieForging Practice
• Several forming steps often required, with separate
die cavities for each step
– Beginning stepsredistribute metal for more uniform
deformation and desired metallurgical structure in
subsequentsteps
– Final stepsbring the part to final geometry
• When drop forging is used,, several blows of the
hammer may be required for each step
49

48. Forging a Rod, Fullering, and Edging
Figure- (a) Stages in forging a connecting rod for an internal combustion engine. Note the amount of flash
required to ensure proper filling of the die cavities. (b) Fullering and (c) edging operations to properly
distribute the material when preshaping the blank for forging.
50

49. Advantages and Limitations
• Advantages of impression-die forging
compared to machining from solid stock:
– Higher production rates
– Less waste of metal
– Greater strength
– Favorable grain orientation in the metal
• Limitations:
– Not capable of close tolerances
– Machining often required to achieve accuracies and
features needed
51

50. Figure- Comparison of metal grain flow in a part that is: (a) hot forged with
finished machining, and (b) machined complete
52

51. Flashless Forging
• Compressionof work in punch and die tooling whose
cavity does not allow for flash
• Starting workpart volume must equal die cavity volume
within very close tolerance
• Process control more demanding than impression-die
forging
• Best suited to part geometries that are simple and
symmetrical
• Often classified as a precision forging process
• Also called true closed-die forging
53

52. Figure- Flashless forging: (1) just before initial contact with workpiece,
(2) partial compression, and (3) final punch and die closure.
Flashless Forging
54

53. Coining
• Special application of a closed-die forging
• Fine details in the die are impresses into the top and bottom
surfaces of the workpart
• Little flow of metal, yet the pressures required to reproduce
the surface details are high
• Used to produce products where exact size and fine details
are required e.g. coins, medals etc.
• Because of the total confinement, the input material must be
accurately sized
55

54. Coining
56
Figure- Coining process: (1) start of cycle, (2) compression stroke, and
(3) ejection of finished part.

55. Open-Die Versus Closed-Die Forging
57

56. Impression-Die Forging Versus
Flashless Forging
Figure- Comparison of closed-die forging with flash (left side ) and precision or flashless
forging (right side) of a round billet.
58

57. Forging Machines
Forging machines are generally classified as
1. Hammers
2. Presses
59

58. Forging Hammers (Drop Hammers)
• Derive energy from the potential energy of the ram,
which is converted into kinetic energy
• Apply impact load against workpart
• Two types:
– Gravity drop hammers - impact energy from falling weight
of a heavy ram
– Power drop hammers - accelerate the ram by pressurized
air or steam
• Disadvantage: impact energy transmitted through
anvil into floor of building
• Commonly used for impression-die forging 60

59. Forging Hammers (Drop Hammers)
Figure- (Left) Double-frame drop forging hammer. (Right)
Schematic diagram of a drop forging hammer.
61

60. Forging Presses
• Apply gradual pressure to accomplish compression
operation
• Types:
– Mechanical press - converts rotation of drive motor into
linear motion of ram
– Hydraulic press - hydraulic piston actuates ram
– Screw press - screw mechanism drives ram
62

61. Principles of Various Presses Used In
Forging
Figure- Schematic illustration of the principles of various forging machines. (a) Mechanical press
with an eccentric drive; the eccentric shaft can be replaced by a crankshaft to give the up-
and-down motion to the ram. (b) Knuckle-joint press. (c) Screw press. (d) Hydraulic
press.
63

62. Upsetting and Heading
• Also called upset forging
• Forging process used to form heads on nails, bolts, and similar
hardware products
• More parts produced by upsetting than any other forging
operation
• Performed cold, warm, or hot on machines called headers or
formers
• Wire or bar stock is fed into machine, end is headed, then
piece is cut to length
• The length of the unsupportedmaterial that can be upset in
one blow without buckling should be limited to three times
the diameter of the bar
• For bolts and screws, thread rolling is then used to form
threads 64

63. Figure- An upset forging operation to form a head on a bolt or similar
hardware item. The cycle consists of: (1) wire stock is fed to the
stop, (2) gripping dies close on the stock and the stop is retracted, (3)
punch moves forward, (4) bottoms to form the head.
Upset Forging
65

64. Figure- Examples of heading (upset forging) operations: (a) heading a nail
using open dies, (b) round head formed by punch, (c) and (d) two
common head styles for screws formed by die, (e) carriage bolt
head formed by punch and die.
Heading (Upset Forging)
66

65. Swaging
• Uses external hammering to reduce the diameter or
produce tapers or points on round bars or tubes
• Also known as rotary swaging or radial forging
• Mandrel sometimes required to control shape and
size of internal diameter of tubular parts
67

66. Figure- Swaging process to reduce solid rod stock; the dies rotate as
they hammer the work . In radial forging, the workpiece rotates
while the dies remain in a fixed orientation as they hammer the
work.
Swaging
68

67. Swaging
Figure-Tube being reduced in a rotary swaging machine.
Figure- Basic components and motions of a
rotary swaging machine. (Note: The
cover plate has been removed to reveal
the interior workings.)
69

68. SwagingWith and Without a Mandrel
Figure- (a) Swaging of tubes without a mandrel; note the increase in wall thickness in the die gap.
(b) Swaging with a mandrel; note that the final wall thickness of the tube depends on the mandrel
diameter. (c) Examples of cross-sections of tubes produced by swaging on shaped mandrels.
Rifling (internalspiralgrooves) in small gun barrels can be made by this process.
70

69. Figure- Examples of parts made by swaging: (a) reduction of solid stock,
(b) tapering a tube, (c) forming a groove on the tube, (d) pointing
on a tube, (e) swaging of neck on a gas cylinder.
71

70. 72
Figure- A variety of swaged parts, some with internal details.

71. Roll Forging
• The cross-section of a bar is reduced or shaped by
passing it through a pair of rolls with shaped
grooves
• The rolls do not turn continuously
• Produces products such as axles, tapered levers
• Littleor no flash is produced
73

72. 74
Figure-(Top) Schematic of the
roll-forging process showing the
two shaped rolls and the stock
being produced.
(Bottom) Rolls from a roll-forging
machine and the various stages
in roll forging a part.

73. Production of Steel Balls
Figure- (a) Production of steel balls by the skew-rolling process. (b) Production of steel balls by upsetting
a cylindrical blank. Note the formation of flash. The balls made by these processes subsequently
are ground and polished for use in ball bearings.
75

74. Trimming
• Cutting operation to remove flash from workpart in
impression-die forging
• Usually done while work is still hot, so a separate
trimming press is included at the forging station
• Trimming can also be done by alternative methods,
such as grinding or sawing
76

75. Figure- Trimming operation (shearing process) to remove the flash
after impression-die forging.
Trimming After Impression-Die Forging
77

76. Costs of a Connecting Rod Made by Forging and
Casting
Figure- Relative unit costs of a
small connecting rod made by
various forging and casting
processes. Note that, for large
quantities, forging is more
economical. Sand casting is the
most economicalprocess for
fewer then about 20,000 pieces.
78

77. Extrusion
• Compressionforming process in which work metal (generally
round billet) is forced to flow through a die opening to
produce a desired cross-sectionalshape
• Process is similar to squeezing toothpasteout of a toothpaste
tube
• In general, extrusion is used to produce long parts of uniform
cross sections throughout extruded length
• May be performed hot or cold; hot more common
79

78. Extrusion
• Commonlyextruded metals: aluminum, magnesium, copper,
and lead
• Typical products: railings for sliding doors, tubing, structural
and architectural shapes, door and window frames etc.
• Two basic types:
– Direct extrusion
– Indirect extrusion
80

79. Typical Extruded Products
Figure- Typical shapes produced by extrusion. (Left)Aluminum products. (Right) Steel
products.
81

80. Figure-Direct extrusion.
Direct Extrusion
82

81. Direct Extrusion
83
Figure-Direct extrusion schematic showing the various equipment components.

82. Comments on Direct Extrusion
• Also called forward extrusion
• As ram approaches die opening, a small portion of
billet remains that cannot be forced through die
opening
• This extra portion, called the butt, must be separated
from extrudate by cutting it just beyond the die exit
• Starting billet cross section usually round
• Final shape of extrudate is determined by die
opening
84

83. Figure- (a) Direct extrusion to produce a hollow or semi-hollow cross
sections; (b) hollow and (c) semi-hollow cross sections.
Hollow and Semi-Hollow Shapes
85

84. Figure- Indirect extrusion to produce (a) a solid cross
section and (b) a hollow cross section.
Indirect Extrusion
86

85. Comments on Indirect Extrusion
• Also called backward extrusion, inverted extrusion and reverse
extrusion
• the die is mounted to the ram rather than at the opposite end
of the container
• As the ram penetrates into the work, the metal is forced to
flow through the clearance in a direction opposite to the
motion of the ram
• To produce hollow cross-sections,the ram is pressed into the
billet, forcing the material to flow around the ram and take a
cup shape
• Limitations of indirect extrusion are imposed by
– Lower rigidity of hollow ram
– Difficulty in supporting extruded product as it exits die 87

86. Advantages of Extrusion
• Variety of shapes possible, especially in hot extrusion
– Limitation: part cross section must be uniform throughout
length
• Grain structure and strength enhanced in cold and
warm extrusion
• Close tolerances possible, especially in cold extrusion
• In some operations, little or no waste of material
88

87. Hot vs. Cold Extrusion
• Hot extrusion - prior heating of billet to above its
recrystallization temperature
– Reduces strengthand increases ductility of the metal,
permitting more size reductions and more complex shapes
• Cold extrusion - generally used to produce discrete
parts
• Generally combined with forging operations
– The term impact extrusion is used to indicate high speed
cold extrusion
89

88. Continuous Versus Discrete Extrusion
• Continuousextrusion operations produce very long sections
in one cycle
• These operations are limited by the size of the billet that can
be loaded into the extrusion container
• More accurately described as semi-continuousoperations
• The long section is subsequentlycut into smaller lengths
• In a discrete extrusion operation, a single part is produced in
each extrusion cycle
• Example: impact extrusion
90

89. Extrusion Ratio
Also called the reduction ratio, it is defined as
where rx = extrusion ratio; Ao = cross-sectional area
of the starting billet; and Af = final cross-sectional
area of the extruded section
• Applies to both direct and indirect extrusion
f
o
x
A
A
r
91

90. Figure- (a) Definition of die angle in direct extrusion; (b) effect of
die angle on ram force.
Extrusion Die Features
92

91. Comments on Die Angle
• Low die angle - surface area is large, which increases
friction at die-billet interface
– Higher friction results in larger ram force
• Large die angle - more turbulence in metal flow
during reduction
– Turbulence increases ram force required
• Optimum angle depends on work material, billet
temperature, and lubrication
93

92. Orifice Shape of Extrusion Die
• Simplest cross section shape is circular die orifice
• Shape of die orifice affects ram pressure
• As cross section becomes more complex, higher pressure and
greater force are required
94
Figure- A complex extruded cross
section for a heat sink
(photocourtesy of Aluminum
Companyof America)

93. Extrusion Presses
• Either horizontal or vertical
– Horizontal more common
• Extrusion presses - usually hydraulically driven, which
is especially suited to semi-continuous direct
extrusion of long sections
• Mechanical drives - often used for cold extrusion of
individual parts such as in impact extrusion
95

94. Other Extrusion Processes
• Direct and indirect extrusion are the principle
methods of extrusion
• Various names are given to operations that are
special cases of the direct and indirect methods
96

95. Impact Extrusion
• Used to make individual components
• Performed at higher speeds and shorter strokes than
conventional extrusion
• The punch impacts the workpart rather than applying
pressureto it
• Impacting can be carried out as forward extrusion, backward
extrusion, or combination of these
• Usually performed cold
• Backward impact extrusion is most common
• Large reductions and high production rates possible
97

96. Figure- Backward and forward impact extrusion with open and closed
dies.
98

97. Cold Extrusion
Figure- (a) Backward, (b) forward, (c) combined forms of cold impact
extrusion.
99

98. 100
Figure- Steps in the forming of a bolt by (cold) impact extrusion, cold heading, and thread
rolling.

99. Bycombining high-speed operations
such as heading, extrusion, bending,
coining, thread rolling, knurling etc.
a wide variety of relatively complex
parts can be cold formed to close
tolerances.
101
Figure- Cold-forming sequence involving cutoff, squaring, two extrusions, an
upset, and a trimming operation.Also shown are the finished part and
the trimmed scrap.

100. 102
Figure- Typical parts made by upsetting and related operations.
• Bycombining high-speed
operations such as heading,
extrusion, bending, coining,
thread rolling, knurling etc.
a wide variety of relatively
complex parts can be cold
formed to close tolerances.
• The larger parts are
generally hot formed and
machined, while the
smaller ones are cold
formed

101. Figure- Manufacture of a spark plug body: (left) by machining from hexagonalbar
stock;(right) by cold forming. Note the reduction in waste.
103

102. Figure- Section of the cold-formed spark plug body of previousfigure, etched to reveal
the flow lines. The cold-formed structure produces an 18% increase in strength over
the machined product.
104

103. Hydrostatic Extrusion
• An adaptation of direct extrusion
• Addresses the problem of friction along the billet-
container interface in direct extrusion
• The billet is surrounded with fluid inside the container
• The fluid is pressurized by the forward motion of the ram
• Friction inside the container and at the die opening is
reduced
• Lower ram force required than in direct extrusion
105

104. Figure- Hydrostatic extrusion
106

105. Wire and Bar Drawing
• Cross-section of a bar, rod, or wire is reduced by
pulling it through a die opening
• Similar to extrusion except work is pulled through die
in drawing (it is pushed through in extrusion)
• Although drawing applies tensile stress, compression
also plays a significant role since metal is squeezed as
it passes through die opening
• Usually performed as cold-working operation
107

106. Figure-Drawing of bar, rod, or wire.
Wire and Bar Drawing
108

107. Area Reduction in Drawing
Change in size of work is usually given by area
reduction:
where r = area reduction in drawing; Ao = original
area of work; and Ar = final work
o
fo
A
AA
r
109

108. Wire Drawing vs. Bar Drawing
• Difference between bar drawing and wire drawing is
stock size
– Bar drawing - large diameter bar and rod stock
– Wire drawing - small diameter stock - wire sizes down to
0.03 mm (0.001 in.) are possible
• Although the mechanics are the same, the methods,
equipment, and even terminology are different
110

109. Drawing Practice and Products
• Drawing practice:
– Usually performed as cold working
– Most frequently used for round cross sections
• Products:
– Wire: electrical wire; wire stockfor fences, coat hangers,
and shopping carts
– Rod stockfor nails, screws, rivets, and springs
– Bar stock:metal bars for machining, forging, and other
processes
111

110. Bar Drawing
• Accomplished as a single-draft operation - the stock
is pulled through one die opening
• Beginning stock has large diameter and is a straight
cylinder
112

111. Figure- Hydraulically operated draw bench for drawing metal bars.
Bar Drawing Bench
113

112. Wire Drawing
• Continuous drawing machines consisting of multiple
draw dies (typically 4 to 12)
– Each die provides a small reduction, so desired total
reduction is achieved by the series
– Annealing sometimes required between dies to relieve
work hardening
114

113. Wire Drawing
Figure- Schematic of wire drawing with a rotating draw block. The rotating
motor on the draw block provides a continuous pull on the incoming wire.
115

114. Figure- Schematic of a multistation synchronized wire-drawing machine. To prevent accumulation or
breakage, it is necessary to ensure that the same volume of material passes through each station in a given
time. The loops around the sheaves between the stations use wire tensions and feedback electronics to
provide the necessary speed control.
Wire Drawing
116

115. Features of a Draw Die
• Entry region - funnels lubricant into the die to
prevent scoring of work and die
• Approach - cone-shaped region where drawing
occurs
• Bearing surface - determines final stock size
• Back relief - exit zone - provided with a back relief
angle (half-angle) of about 30
• Die materials: tool steels or cemented carbides
117

116. Figure-Drawdie for drawing of round rod or wire.
Draw Die Details
118

117. Preparation of Work for Drawing
• Annealing – to increase ductility of stock
• Cleaning - to prevent damage to work surface and
draw die
• Pointing – to reduce diameter of starting end to
allow insertion through draw die
119

118. References
• Degar o’s Materials A d Processes I Ma ufacturi g, th Ed. By J.T Black,
R.A. Kohser; John Wiley And Sons
• Fundamentals Of Modern Manufacturing ; Materials, Processes, And
Systems, 3rd Ed. By Mikell P. Groover; John Wiley And Sons
• Manufacturing Engineering And Technology, 5th Ed. By S. Kalpakjian, S. R
Schmid; Pearson Education Inc.
• http://www.forging.org/
• http://manufacturing.stanford.edu/hetm.html
• http://metals.about.com/library/weekly/aa-metalworking-videos2.htm
• http://www.engineeringmotion.com/videos/load/recent
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119. Any Questions?
121
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