This document provides information on various bulk deformation processes used to shape metals, including forging, rolling, extrusion, drawing, and swaging. It discusses the general characteristics, applications, advantages/disadvantages, and costs associated with each process. Diagrams are also included to illustrate stages of specific processes like impression die forging, thread rolling, and shape rolling. The document contains a comprehensive overview of common bulk deformation techniques for metalworking.

1. Bulk-Deformation Processes
TABLE 6.1 General characteristics of bulk deformation processes.
PROCESS GENERAL CHARACTERISTICS
Forging Production of discrete parts with a set of dies; some finishing operations usually
necessary; similar parts can be made by casting and powder-metallurgy techniques;
usually performed at elevated temperatures; dies and equipment costs are high;
moderate to high labor costs; moderate to high operator skill.
Rolling
Flat Production of flat plate, sheet, and foil at high speeds, and with good surface finish,
especially in cold rolling; requires very high capital investment; low to moderate labor
cost.
Shape Production of various structural shapes, such as I-beams and rails, at high speeds;
includes thread and ring rolling; requires shaped rolls and expensive equipment; low to
moderate labor cost; moderate operator skill.
Extrusion Production of long lengths of solid or hollow products with constant cross-sections,
usually performed at elevated temperatures; product is then cut to desired lengths;
can be competitive with roll forming; cold extrusion has similarities to forging and is
used to make discrete products; moderate to high die and equipment cost; low to
moderate labor cost; low to moderate operator skill.
Drawing
Swaging
Production of long rod, wire, and tubing, with round or various cross-sections; smaller
cross-sections than extrusions; good surface finish; low to moderate die, equipment
and labor costs; low to moderate operator skill.
Radial forging of discrete or long parts with various internal and external shapes;
generally carried out at room temperature; low to moderate operator skill.

2. Impression-Die Forging
FIGURE 6.14 Schematic illustration of stages in impression-die forging. Note the formation
of flash, or excess material that is subsequently trimmed off.

3. Flat-And-Shape-
Rolling Processes
FIGURE 6.29
Schematic outline of
various flat-and-shape-
rolling processes.
Source: American Iron
and Steel Institute.

4. Classification
Name Characters Cost Skill
Forging
Production of discrete parts with
dies
High High skill
Rolling (Flat) Flat plate, sheet, foil in long length High Equipment cost Low skill
Rolling (shape) Various structural shapes, I-beam Expensive Equipment Moderate
Extrusion
Long length of solid or hollow
products with constant cross-
section.
Moderate to high die and
equipment cost
Moderate
Drawing Production of long rod and wire Moderate cost Low skill
Swaging
Radial forging of discrete or long
parts with various internal and
external shapes; generally carried
out at room temperature;
Moderate cost
low to
moderate
operator
skill.
Bulk-Deformation Processes

5. Grain Flow Lines
FIGURE 6.2 Grain flow lines in
upsetting a solid steel cylinder at
elevated temperatures. Note the
highly inhomogenous deformation
and barreling. The different shape
of the bottom, section of the
specimen (as compared with the
top) results from the hot specimen
resting on the lower, cool die
before deformation proceeded.
The bottom surface was chilled;
thus it exhibits greater strength
and hence deforms less than the
top surface. Source: J. A. Schey et
al., IIT Research Institute.

6. Finite Element Simulation
FIGURE 6.11 Plastic
deformation in forging as
predicted by the finite-
element method of analysis.
Source: Courtesy of
Scientific Forming, Inc.

7. Plastic Deformation in Plane Strain
FIGURE 6.13 Examples of plastic
deformation processes in plane strain,
showing the h/L ratio. (a) Indenting with
flat dies. This operation is similar to
cogging, shown in Fig. 6.19. (b)
Drawing or extrusion of strip with a
wedge-shaped die, described in Sections
6.4 and 6.5. (c) Ironing; see also Fig.
7.54. (d) Rolling, described in Section
6.3. As shown in Fig. 6.12, the larger the
h/L ratio, the higher the die pressure
becomes. In actual processing, however,
the smaller this ratio, the greater is the
effect of friction at the die-workpiece
interfaces. The reason is that contact
area, and hence friction, increases with a
decreasing h/L ratio.

8. Impression-Die Forging
FIGURE 6.14 Schematic illustration of stages in impression-die forging. Note the
formation of flash, or excess material that is subsequently trimmed off.
Analysis
Simple shapes, without flash
Simple shapes, with flash
Complex shapes, with flash
3-5
5-8
8-12
F = (Kp)(Yf)(A)
TABLE 6.2 Range of Kp values in Eq. (6.21) for impression-die forging.

9. Load-Stroke Curve in Closed-Die Forging
FIGURE 6.15 Typical load-
stroke curve for closed-die
forging. Note the sharp increase in
load after the flash begins to form.
In hot-forging operations, the
flash requires high levels of
stress, because it is thin-that is, it
has a small h-and cooler than the
bulk of the forging. Source: After
T. Altan.

10. Heading
FIGURE 6.17 Forging heads on
fasteners such as bolts and rivets.
These processes are called heading.
Piercing Operations
FIGURE 6.18 Examples of piercing
operations.

11. Cogging Operation
FIGURE 6.19 Schematic illustration of a cogging operation on a rectangular bar. With
simple tools, the thickness and cross-section of a bar can be reduced by multiple cogging
operations. Note the barreling after cogging. Blacksmiths use a similar procedure to reduce
the thickness of parts in small increments by heating the workpiece and hammering it
numerous times.

12. Roll Forging Operation
FIGURE 6.20 Schematic illustration of a roll forging (cross-rolling) operation. Tapered leaf
springs and knives can be made by this process with specially designed rolls. Source: After
J. Holub.

13. Manufacture of Spherical Blanks
FIGURE 6.21 Production of steel balls for bearings
by the skew-rolling process. Balls for bearings can
also be made by the forging process shown in Fig.
6.22.
FIGURE 6.22 Production of steel
balls by upsetting of a cylindrical
blank. Note the formation of flash.
The balls are subsequently ground
and polished for use as ball
bearings and in other mechanical
components.

14. Internal Defects In Forging
FIGURE 6.24 Internal defects produced in a forging because of an oversized billet. The die
cavities are filled prematurely, and the material at the center of the part flows past the filled
regions as deformation continues.
FIGURE 6.23 Laps
formed by buckling of
the web during
forging.

15. Defect Formation In Forging
FIGURE 6.25 Effect of fillet radius on defect formation in forging. Small fillets (right side
of drawings) cause the defects. Source: Aluminum Company of America.

16. Forging A Connecting Rod
FIGURE 6.26 Stages in forging a connecting rod for an internal combustion engine. Note
the amount of flash that is necessary to fill the die cavities properly.

17. Features Of A Forging Die
FIGURE 6.27 Standard terminology for various features of a typical forging die.
Hot-Forging Temperature Ranges
Metal C F Metal C F
Aluminum alloys
Copper alloys
Nickel alloys
400-450
625-950
870-1230
750-850
1150-1750
1600-2250
Alloy steels
Titanium alloys
Refractory alloys
925-1260
750-795
975-1650
1700-2300
1400-1800
1800-3000
TABLE 6.3 Hot-forging temperature ranges for various metals.

18. Presses Used In Metalworking
FIGURE 6.28 Schematic illustration of various types of presses used in metalworking. The
choice of the press is an important factor in the overall operation.

19. Stages in Shape Rolling of an H-section
part

20. Shape Rolling-
Angles

21. Special Rolling
Special Products (Shapes)
Special Methods
Non-Uniform Rolling (Deformation)

22. Thread Rolling
Bulk deformation process used to form threads on cylindrical
parts by rolling them between two dies
Most 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 due to work hardening
Better fatigue resistance due to compressive stresses
introduced by rolling

23. Thread rolling with flat dies:
(1) start of cycle, and (2) end of cycle

24. •The thread is formed by the axial flow of material in the work piece.
• The grain structure of the material is not cut, but is distorted to follow the thread form.
• Rolled threads are produced in a single pass at speeds far in excess of those used to
cut
threads.
• The resultant thread is very much stronger than a cut thread. It has a greater resistance
to mechanical stress and an increase in fatigue strength. Also the surface is burnished and
work hardened.

25. Ring Rolling

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

29. (a) Schematic illustration of
Ring-rolling operation.
Thickness reduction
results in an increase in
the part diameter.
(b) Examples of cross-
sections that can be
formed by ring-rolling

30. Production of Seamless Pipe & Tubing

35. Assel Method

36. Transverse Rolling
•Using circular wedge rolls.
• Heated bar is cropped to length and
fed in transversely between rolls.
• Rolls are revolved in one direction.

37. Powder Rolling
Metal powder is introduced between the rolls and compacted into a
‘green strip’, which is subsequently sintered and subjected to further
hot- working and/ or cold working and annealing cycles.
Advantage :
- Cut down the initial hot- ingot breakdown step (reduced
capital investment).
- Economical - metal powder is cheaply produced during the
extraction process.
- Minimise contamination in hot- rolling.
- Provide fine grain size with a minimum of preferred
orientation.

38. Powder Rolling

39. Continuous casting and hot rolling

40. Continuous rolling

41. Example for hot strip mill
process

43. Hot and Cold Flat Rolling

44. Changes in grain structure during
hot-rolling

45. Other CharacteristicsOther Characteristics
Residual stresses – produces:
Compressive residual stresses on the surfaces
Tensile stresses in the middle
Tolerances
Cold-rolled sheets: (+/- ) 0.1mm – 0.35mm
Tolerances much greater for hot-rolled plates
Surface roughness
Cold rolling can produce a very fine finish
Hot rolling & sand have the same range of surface finish
Gauge numbers – the thickness of a sheet is identified by a gauge number

46. Schematic Illustration of various roll arrangements : (a) two-
high; (b) three-high; (c) four-high; (d) cluster mill

47. ‫نورد‬ ‫در‬ ‫مدلسازی‬
A- Mathematical and Physical Simulation
: FDM‫شرا‬ ‫برای‬‫ي‬‫پ‬ ‫و‬ ‫دوبعدی‬ ‫ط‬‫ي‬‫کامل‬ ‫وستگی‬
‫.توابع‬
: FEM‫شرا‬ ‫برای‬‫ي‬‫ناپ‬ ‫اطلعات‬ ‫حتی‬ ‫و‬ ‫بعدی‬ ‫سه‬ ‫ط‬‫ي‬‫وسته‬
B- Knowledge Based Modeling
‫ها‬ ‫داده‬ ‫اساس‬ ‫بر‬

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49. ‫غ‬ ‫نورد‬‫ي‬‫متقارن‬ ‫ر‬)Asymetric Rolling(
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‫پا‬ ‫خنثی‬ ‫نقطه‬‫يي‬‫نی‬
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‫بال‬‫ي‬‫ی‬
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-‫ا‬ ‫در‬‫ي‬‫دل‬ ‫به‬ ‫روش‬ ‫ن‬‫ي‬‫تنش‬ ‫اعمال‬ ‫ل‬
‫ب‬ ‫معادل‬ ‫کرنش‬ ‫برشی‬ ‫های‬‫ي‬‫شتری‬
.‫شود‬ ‫می‬ ‫اعمال‬

51. Drawing
FIGURE 6.62 Variables in
drawing round rod or wire.
FIGURE 6.63 Variation in strain and
flow stress in the deformation zone in
drawing. Note that the strain increases
rapidly toward the exit. The reason is that
when the exit diameter is zero, the true
strain reaches infinity. The point Ywire
represents the yield stress of the wire.

52. Tube Drawing
FIGURE 6.67 Various methods of tube drawing.

53. Swaging
FIGURE 6.71 Schematic illustration of the swaging
process: (a) side view and (b) front view. (c) Schematic
illustration of roller arrangement, curvature on the four
radial hammers (that give motion to the dies), and the radial
movement of a hammer as it rotates over the rolls.
FIGURE 6.72 Reduction of outer and inner diameters of
tubes by swaging. (a) Free sinking without a mandrel. The
ends of solid bars and wire are tapered (pointing) by this
process in order to feed the material into the conical die. (b)
Sinking on a mandrel. Coaxial tubes of different materials can
also be swaged in one operation.

54. Cross-Sections Produced By Swaging
FIGURE 6.73 (a) Typical cross-sections produced by swaging tube blanks with a constant wall
thickness on shaped mandrels. Rifling of small gun barrels can also be made by swaging, using a
specially shaped mandrel. The formed tube is then removed by slipping it out of the mandrel. (b) These
parts can also be made by swaging.