Forging and
Sheet Metal Forming
Automotive Production Engineer
T. Udomphol
by
Dr. Tapany Udomphol
School of Metallurgical Engineering
Suranaree University of Technology
Suranaree University of Technology
September 2007
Forging and
Sheet Metal Forming
Outline
Part I: Forging of Metals (
)
T. Udomphol
• Introduction to metal forming
• Hot and cold working
• Deformation geometry
• Classification of forging processes
• Die design and die materials
• Metal flow in forging
• Force in metal forging
• Forging defects
Suranaree University of Technology
September 2007
Forging and
Sheet Metal Forming
T. Udomphol
Outline Part II: Sheet metal forming (
)
• Introduction to sheet metal forming
• Sheet metal parts
• Classification of sheet metal forming
• Forming limit criteria
• Defects in formed parts
Suranaree University of Technology
September 2007
T. Udomphol
Introduction to metal forming
Suranaree University of Technology
September 2007
Introduction to metal forming
There are a wide range of different metal parts involved in an
automobile production.
T. Udomphol
www.designchain.com
encarta.msn.com
Suranaree University of Technology
September 2007
Introduction to metal forming
T. Udomphol
Casting
Metal
processing
Suranaree University of Technology
Cutting
i.e.
i.e.
Forming
i.e.
Joining
i.e.
• Gravity die casting
• Pressure die casting
• Centrifugal casting
• Injection moulding
• Rotational moulding
• Electrochemical machining
• Electrical discharge machining
• Single/multiple point cutting
• Grinding
• Sheet metal forming
• Forging
• Rolling
• Extrusion
• Wire drawing
• Fusion welding (arc, laser,
electron beam)
• Solid state welding (friction)
•Mechanical joining
September 2007
Classification of metal forming
by subgroups
T. Udomphol
Metal forming
Compressive
forming
Combined tensile
and compressive
forming
Tensile
forming
•Rolling
•Pulling through a die
•Stretching
•Open die forming
•Deep drawing
•Expanding
•Closed die forming
•Flange forming
•Recessing
•Indenting
•Spinning
•Pushing through a die
•Upset bulging
Suranaree University of Technology
Forming by
bending
•Bending with
linear tool
motion
•Bending with
rotary tool
motion
Forming by
shearing
•Joggling
•Twisting
•Blanking
•Coining
September 2007
Introduction to metal forming
T. Udomphol
Forgings
Forged wheels
Suranaree University of Technology
Forged aluminium
pistons and
connecting rods
Hot forming
product
September 2007
Introduction to metal forming
Net shape and metal powder forming products
T. Udomphol
Powder metal
forming parts
Sintered
metal parts
Metal injection
moulding parts
Net shape
metal power
parts
Suranaree University of Technology
September 2007
Introduction to metal forming
Metal Sheet forming products
T. Udomphol
www.numerica-srl.it
Electromagnetic
forming of
automotive parts
www.mse.eng.ohio-state.edu
Suranaree University of Technology
Stamped plates
September 2007
Introduction to metal forming
T. Udomphol
www.ducommunaero.com
www.macri.it
Forging machine
Suranaree University of Technology
September 2007
Hot and cold working
T. Udomphol
Working
processes
• The methods used to mechanically shape metals
into other product forms.
Hot working (0.6-0.8Tm)
• Primary process
• Recrystallisation
Cold working (< 0.3Tm)
• Secondary process
• No recrystallisation
Suranaree University of Technology
September 2007
Annealing mechanisms
in cold worked metals
T. Udomphol
• Mechanical properties change due
to temperature after cold working
Suranaree University of Technology
September 2007
Annealing mechanisms
in cold worked metals
Properties
T. Udomphol
Ductility
Strength
Hardness
Cold worked and
recovered
Recovery
~0.3Tm
New grains
Recrystallisation
~0.5Tm
Temperature
Grain growth
Annealing mechanisms in cold worked metals
Suranaree University of Technology
September 2007
T. Udomphol
Effects of grain size and strain
on recrystallisation temperature
Schematic of recrystallisation diagram
Smaller grains
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Better strength/properties
September 2007
T. Udomphol
Effects of grain size and strain
on recrystallisation temperature
Flow stress of aluminium as a function of
strain at different temperature
Temp
Flow stress
Suranaree University of Technology
Flow curves of Cu Zn28
Strain rate
Flow stress
September 2007
Advantages and disadvantages
of hot and cold working
Hot working
T. Udomphol
Advantages
• Low flow stress + high ductility
• Pore sealed up
• Smaller grains
• Softer metals
Disadvantages
• Surface oxidation
• Poor dimensional control
• Hot shortness
• Difficult handling
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Cold working
Advantages
• Stronger
• Good surface finish
• Good dimensional control
• Easy handling
Disadvantages
• High deformation
• Reduced ductility
• Expensive equipment
September 2007
Deformation geometry
Effect of principal stresses
in metal working
Biaxial-plane stress condition
• Two principal stresses, 1 and
• EX: Sheet metal forming
2.
Triaxial-plane strain condition
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• Three principal stresses, 1 ,
, where 1 > 2 > 3.
• EX: Forging, rolling extrusion
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Biaxial
2
and
Triaxial
3
September 2007
Part I: Forging of metals
• Forging is the working of metal into a useful
shape by hammering or pressing.
T. Udomphol
• Primitive blacksmith
• Parts ranging in size of a bolt to a turbine
rotor.
• Most carried out hot, although certain metals
may be cold-forged.
www.eindiabusiness.com
Suranaree University of Technology
www.prime-metals.com
September 2007
Classification of forging
processes
T. Udomphol
By equipment
1) Forging hammer or drop hammer
2) Press forging
By process
1) Open - die forging
2) Closed - die forging
Suranaree University of Technology
September 2007
T. Udomphol
Forging machines
Suranaree University of Technology
September 2007
Forging machines
T. Udomphol
• The energy supplied by the blow
is equal to the potential energy
due to the weight of the ram and
the height of the fall.
Drop hammer
Potential energy = mgh
• Mass production (60-150 blow / min)
• Dies are subject to impact loading
Suranaree University of Technology
September 2007
Forging machines
T. Udomphol
Hydraulic Press forging
• Continuous forming at slower rate
• Deeper penetration
• Expensive equipment
• Heat loss from workpiece
(long contact)
• Die life
Suranaree University of Technology
September 2007
Closed and open die forging
T. Udomphol
Open-die forging
Closed-die forging
Impression-die
forging
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September 2007
T. Udomphol
Open--die forging
Open
• Flat dies
• Simple shape
• Large objects.
• Pre-forming
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September 2007
T. Udomphol
Close--die forging (Impression forging)
Close
• Workpiece is formed under high
pressure in a closed cavity.
• Small components
• Precision forging
• Expensive die
Suranaree University of Technology
September 2007
Forging load
T. Udomphol
Die cavity
completely
filled
Flash begins
to form
Dies contact
workpiece
Forging complete
Forging load
Forging stroke
Typical curve of forging load vs. stroke for
closed-die forging.
Suranaree University of Technology
Flash is the excess metal, which
squirts out of the cavity as a thick
ribbon of metal.
September 2007
Functions of flash
T. Udomphol
The flash serves two purposes:
• Acts as a ‘safety value’ for excess metal.
• Builds up high pressure to ensure that
the metal fills all recesses of the die cavity.
Remark: It is necessary to achieve complete filling of the forging cavity
without generating excessive pressures against the die that may
cause it to fracture.
Suranaree University of Technology
September 2007
T. Udomphol
Closed--die design
Closed
Considerations
• workpiece volume and weight
• number of preforming steps and their configuration
• flash dimensions in preforming and finishing dies
the load and energy requirement for each forging operation, for
example; the flow stress of the materials, the fictional condition,
the flow of the material in order to develop the optimum geometry for
the dies.
Suranaree University of Technology
September 2007
T. Udomphol
Shape classification
Suranaree University of Technology
September 2007
T. Udomphol
Shape classification
Suranaree University of Technology
September 2007
Die set and forging steps for
automobile engine connecting rod
Preforming of a round piece in an open die arrangement.
Rough shape is formed using a block die.
Finishing die gives final tolerances and surface finish.
Removal of flash (excess metal).
T. Udomphol
•
•
•
•
Steering knuckle
Rail
Flange
http://www.hirschvogel.de/en/produkti
onsverfahren/warmumformung.php
See simulation
Suranaree University of Technology
September 2007
General considerations
for preform design
• Metal used = Metal preform + Flash.
• Concave radii of the preform > radii on the final forging part.
• Cross section of the preform should be higher and narrower than the
T. Udomphol
final cross section.
draft angle
web
rib
• Shapes with thin and long sections or
projections (ribs and webs) are more
difficult to process due to
• higher surface area per unit volume
• increasing friction
• temperature effects.
Some typical nomenclature
Suranaree University of Technology
September 2007
General considerations
for preform design
• Smooth metal flow – symmetry dies
• Avoid shape change
T. Udomphol
• Minimum flash to do the job.
• Tapered or drafted to facilitate removal of the finished piece.
• Draft allowance is approximately 3-5o outside and 7-10o inside.
• Counterlock to prevent side thrust.
draft angle
web
rib
Suranaree University of Technology
Counterlock
Side thrust
September 2007
Die materials
www.nitrex.com
T. Udomphol
Required properties
• Thermal shock resistance
• Thermal fatigue resistance
• High temperature strength
• High wear resistance
• High toughness and ductility
• High hardenability
• High dimensional stability
during hardening
• High machinability
Suranaree University of Technology
Forging die
Die materials: alloyed steels (with Cr,
Mo, W, V), tool steels, cast steels or cast
iron. (Heat treatments such as nitriding or
chromium plating)
1) Carbon steels with 0.7-0.85% C are
appropriate for small tools and flat
impressions.
2) Medium-alloyed tool steels for
hammer dies.
3) Highly alloyed steels for high
temperature resistant dies used in
presses and horizontal forging
machines.
September 2007
Die materials
Forging
materials
T. Udomphol
Forging dies
Die inserts
Steels
Copper and copper alloys
DIN
AISI
DIN
AISI
Light alloys
DIN
AISI
C70 W2
-
C85 W2
-
60MnSi4
-
X30WCrV53
H21
X30WCrV53
-
40CrMnMo7
-
X38CrMoV51
H11
X38CrMoV51
H11
X32CrMoV33
H10
55NiCrMoV6
6F2
55NiCrMoV6
56NiCrMoV7
6F3
56NiCrMoV7
6F2
57NiCrMoV77
-
35NiCrMo16
-
X38CrMoV51
57NiCrMoV77
-
57NiCrMoV77
6F3
H11
X30WCrV93
H21
X38CrMoV51
H11
X32CrMoV33
H10
X32CrMoV33
H10
X32CrMoV33
H10
X30WCrV53
-
X30WCrV52
-
X30WCrV53
-
X37CrMoW51
H12
Suranaree University of Technology
September 2007
T. Udomphol
Die life improvement
Current forging
Future forging
To increase die life
1) Improving die materials such
as using composite die or
2) Using surface coating or selflubricating coatings
Ultra hard surface coatings
• Improve die life.
• Reduce energy input.
• Reduce die-related uptime
and downtime.
http://www.eere.energy.gov/industry/supporting_industries
/pdfs/innovative_die_materials.pdf
Suranaree University of Technology
• Reduce particulate emission
from lubricants.
September 2007
Die failures
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Wear (abrasion)
Thermal fatigue
Mechanical fatigue
Permanent deformation
• Different parts of dies are liable to permanent deformation and wear
resulting from mechanical and thermal fatigue
Suranaree University of Technology
September 2007
T. Udomphol
Increasing reduction
Metal flow in forging
Deformation
bands
associated
with plastic
instability.
Schematic representation of shear band
formation in compression of a cylinder.
Finite element analysis of upsetting an aluminium cylinder
Suranaree University of Technology
September 2007
T. Udomphol
Metal flow in forging
Grain structure resulting from
(a) forging, (b) machining and
(c) casting.
Fibre structure in forged steels
Suranaree University of Technology
September 2007
Metal flow in forging
T. Udomphol
Metal flow in forging
• Identify the neutral surface
• Metal flows away from the
neutral surface in a direction
perpendicular to the die motion.
Suranaree University of Technology
September 2007
Metal flow in forging
Cold forging
Step II
Step III
Step IV
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Step I
• Forging of nut and bolt
www.qform3d.com
Suranaree University of Technology
September 2007
Metal flow in forging
Cold forging
• Forging of nut and bolt
Step II
Step III
T. Udomphol
Step I
www.qform3d.com
Suranaree University of Technology
September 2007
Metal flow in forging
T. Udomphol
Hot forging
Titanium alloy being forged at 930oC to
produce preliminary turbine blade pre-form.
http://www.qform3d.com/en/59.html
Suck in flaw
www.qform3d.com
Suranaree University of Technology
September 2007
Metal flow in forging
•AISI 1040 being forged from a square
bar at 1200oC to produce a shaft.
T. Udomphol
Hot forging
• Extensive metal flow into flash
• Incomplete fill up at the upper part
www.qform3d.com
Suranaree University of Technology
September 2007
Metal flow in forging
• DIN/C43 being forged from a round
bar at 1250oC to produce a shaft fork.
T. Udomphol
Hot forging
• Possible die filling with minimum
flash used.
www.qform3d.com
Suranaree University of Technology
September 2007
Metal flow in forging
Forging from compact bar
T. Udomphol
www.qform3d.com
• Powder compact bar of 0.78
density being forged.
• The density increases first
in the intermediate area then
spread throughout the cross
section.
Suranaree University of Technology
September 2007
Forces in metal forging
Friction between two surfaces
T. Udomphol
F  i Ar  i
 

P pAr
p
…Eq.1
Where
= frictional coefficient
= the shearing stress at the interface
P = the load normal to the interface
F = the shearing force
Ar= summation of asperity areas in contact
p = the stress normal to the interface
Suranaree University of Technology
September 2007
Forces in metal forging
T. Udomphol
The calculation of forging load can be
considered in three cases
1. No friction
2. Small friction
3. Sticky friction
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September 2007
No friction
Do
T. Udomphol
ho
h
P oA
Where
P
D
Do2 ho  D 2 h
….Eq. 2
is the compressive force
is the yield stress of the metal
is the cross sectional area of the metal.
o
A
4 o Ah
4P
4 Ph
p


2
2
D
Do ho Do2 ho
Suranaree University of Technology
….Eq. 3
September 2007
Small friction
T. Udomphol
• Small friction (homogeneous forging)
• Assumption:
- no barrelling
- small thickness,
Then
- frictional conditions on the top
and bottom faces of the disk
are a constant coefficient of
Coulomb friction;
Suranaree University of Technology


p
…Eq.4
Where
= frictional coefficient
= the shearing stress at the interface
p = the stress normal to the interface
September 2007
Small friction
• Small friction
(non-homogeneous forging)
Pmax
Friction hill
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X=0
X=a
P
o
-a
h
a
X
Functions of a metal working lubricant
P
Suranaree University of Technology
- Reduces deformation load
- Increases limit of deformation before fracture
- Controls surface finish
- Minimises metal pickup on tools
- Minimises tool wear
- Thermally insulates the workpiece and the tools
- Cools the workpiece and/or tools
September 2007
Small friction
Forging stress
 2

 y   exp  a  x 
 h

T. Udomphol
'
o
 2 a 

 h 
y
 o' exp
Friction hill
 2
a  x 
 h

 o' exp 
….Eq. 5
Average forging pressure
‘o
a
-a
X
 a 
p   o' 1 
 ….Eq. 6
h 

_
a/h
Forging pressure
Suranaree University of Technology
x = -a
x=0
x=a
September 2007
High friction (Sticky friction)
Forging stress
ax 
 1
 h

T. Udomphol
 y   o' 
a
h


y
 o'  1
….Eq. 7
ax 
 1
h


 o' 
Friction hill
‘o
Average forging pressure
a
-a
X
2
 a

p
 o   1 ….Eq. 8
3  2h 
_
a/h
Forging pressure
Suranaree University of Technology
x = -a
x=0
x=a
September 2007
Example:
Dieter, page 574-575
A block of lead 25x25x150 mm3 is pressed between flat dies to a size
6.25x100x150 mm3. If the uniaxial flow stress
o
= 6.9 MPa and
= 0.25,
T. Udomphol
determine the pressure distribution over the 100 mm dimension (at x = 0, 25
and 50 mm) and the total forging load in the sticky friction condition.
 2

y 
 o exp  a  x 
3
 h

2
where
 o' 
2
3
o
At the centreline of the slab (x = 0)
 max 
2 ( 6 .9 )
 2(0.25)
50  0  435MPa
exp 
3
 6.25

Likewise, at 25 and 50 mm, the stress distribution will be 58.9 and 8.0 MPa
respectively.
Suranaree University of Technology
September 2007
Example:
Dieter, page 574-575
The mean forging load (in the sticky friction condition) is
_
T. Udomphol
p
_
p
2
3
 a

 1
 2h 
o
2(6.9)  50

 1  39.8MPa

3  12.5 
We calculate the forging load on the assumption that the stress distribution
is based on 100 percent sticky friction. Then
The forging load is P
Suranaree University of Technology
= stress x area
= (39.8x106)(100x10-3)(150x10-3)
= 597 kN
= 61 tonnes.
September 2007
Defects in forging
• Incomplete die filling.
T. Udomphol
• Die misalignment.
files.bnpmedia.com
Fluorescence penetrant
reveals Forging laps
• Forging laps.
• Incomplete forging penetration- should
forge on the press.
• Microstructural differences resulting in
pronounced property variation.
• Hot shortness, due to high sulphur
concentration in steel and nickel.
• Residual stresses
www.komatsusanki.co.jp
See simulation
Suranaree University of Technology
September 2007
Forging of automobile parts
www.jocmachinery.com
T. Udomphol
www.jocmachinery.com
• Metals to be forged
• Shape and size
• Forging temperature
• Strain rate
• Forging load
• Lubrication
Suranaree University of Technology
• Die design
• Die materials
• Die life
September 2007
Part II: Sheet metal forming
Sheet metal forming
T. Udomphol
• Permanent deformation by
cold forming (RT).
• Complex 3D shapes.
• The process is carried out in the
plane of sheet by tensile forces
with high ratio of surface area
to thickness.
• Friction conditions at the
tool-metal interface.
• High rate of production
and formability
Suranaree University of Technology
September 2007
Classification of sheetsheet-metal
forming
(Base on operation)
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Classification
Blanking
Suranaree University of Technology
Punching
Stretching
Stretching
Deep drawing
September 2007
Classification of sheetsheet-metal
forming
(Base on operation)
T. Udomphol
Classification
Coining
Suranaree University of Technology
Stamping
Ironing
September 2007
Classification of sheetsheet-metal
forming
(Base on operation)
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Classification
Folding
Bending
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Roll forming of sheet
Wiping down a flange
September 2007
Tooling
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Basic tools
• Punch  A convex tool for making
holes by shearing, making surface or
displacing metal with a hammer.
• Die
 A concave die (female part).
Punches and dies
Die materials:
Punch and die in stamping
Suranaree University of Technology
• High alloyed steels heat
treated for the punches and
dies.
September 2007
Compound and transfer dies
Compound dies
www.lyons.com
T. Udomphol
• Several operations in one stroke.
• Combined processes and create a
complex product in one shot.
• Stamping processes of thin sheets.
Transfer dies
www.deltatooling.co.jp/
• Also called compound dies.
• The part is moved from station to
station within the press for each
operation.
Suranaree University of Technology
September 2007
Introduction to metal forming
T. Udomphol
Die set consists of
1) Punch holder
2) Die block
3) Pilot
4) Striper plate
Schematic diagram of a die set
pilot
Suranaree University of Technology
September 2007
Forming methods
T. Udomphol
There are a great variety of sheet metal forming methods,
mainly using shear and tensile forces in the operation.
• Progressive forming
• Shearing and blanking
• Hydroforming
• Bending and contouring
• Stretch forming
• Spinning process
• Explosive forming
• Deep drawing
• Stamping
Suranaree University of Technology
September 2007
Progressive forming
www.hillengr.com
Punch
T. Udomphol
Stripper
plate
Die
Strip
washer
Progressive die
• Optimise the material usage.
• Determining factors are
1) volume of production
washers
Suranaree University of Technology
2) the complexity of the shape
September 2007
Hydroforming
• Using Rubber or polyurethane pad as dies.
• Single - action hydraulic press.
T. Udomphol
• Pressure medium- water or oil.
• Transmits a nearly uniform hydrostatic pressure
against the sheet.
• Pressure ~ 10 MPa or higher
www.thefabricator.com
Hydroforming
Suranaree University of Technology
September 2007
Stretch forming
• Using tensile forces, normally for uniform cross section).
T. Udomphol
• required materials with appreciable ductility.
Ram
Ram
www.ducommunaero.com
Suranaree University of Technology
September 2007
Explosive forming
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• Explosive charge is detonated in medium (water) at an appropriate
standoff distance from the sheet blank at a very high velocity.
• The shockwave propagating from the explosion serves as a
‘friction-less punch’
Suranaree University of Technology
September 2007
Stamping
T. Udomphol
• Key factors: data collections on die sets, die
failure and material handling damage and machine
failure to identify weak areas in the stamping
process.
www.ugs.com/
www.fpi.co.th
• Materials require good ductility, work
hardening and strength
img.alibaba.com
Panel, fender, bumper
Automotive stamped parts
Suranaree University of Technology
Automobile panel die
September 2007
Stamping
T. Udomphol
• Multi-cone design giving structural
integrity and rigidity equivalent to
a steel beam panel at half the weight,
and without cutouts,
www.psc.edu
Suranaree University of Technology
Aluminium inner hood panel
September 2007
Shearing and blanking
Clearance
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• Proper
(a) Proper clearance
Ragged
surface
(normally 2-10% thickness)
 clean fracture surface.
• Insufficient ragged fracture surface.
• Excessive  greater distortion, greater energy
required to separate metal.
(b) Insufficient clearance
blurr
Thickness
clearance
(c) Excessive clearance
Suranaree University of Technology
September 2007
Bending and contouring
www.macri.it
T. Udomphol
Wiper rolls
Form block
www.lathes.co.uk
Clamp
Clamp
Tension
Suranaree University of Technology
September 2007
Bending and contouring
• Outer surface  strained.
• Inner surface contracted.
T. Udomphol
b/h
R
thickness on
bending
Springback
Suranaree University of Technology
biaxiality
Strain, ductility
Cracks occur near the
centre of the sheet
September 2007
Spinning process
• Deep parts of circular symmetry
such as tank heads, television cones.
T. Udomphol
Materials: aluminium and alloys, high
strength - low alloy steels, copper,
brass and alloys, stainless steel,
(a) Manual spinning
Suranaree University of Technology
(b) Shear spinning
September 2007
Deep drawing
• Shaping flat sheets into cup-shaped articles.
Examples: bathtubs, shell cases, automobile panels.
T. Udomphol
A cup is subjected to
three different types of
deformation.
Lamp cover
Stresses and deformation in a section from a drawn cup
Suranaree University of Technology
September 2007
Deep drawing
• Die radius – 10 x sheet thickness.
T. Udomphol
• Punch radius – Clearance between punch
and die ~10-20% > sheet thickness.
• Hold-down pressure – ~ 2% of
o
and
u.
• Lubrication of die side.
• Material properties - low yield stress, high
work hardening rates.
Suranaree University of Technology
Thickness profile of drawn cup
Clearance > 10-20%
thickness.
September 2007
Forming limit criteria
T. Udomphol
• Stretching of circles into ellipses
after punching
Major strain
120
• Percentage changes in these
strains are compared in the diagram.
100
1(%)
Failure
80
60
2
-40
Grid analysis (a) before (b) after deformation of
sheet.
Suranaree University of Technology
-20
B
AK steel
2
Safe
40
1
A
1
20
0
20
40
Minor strain
60
2(%)
80
100
Forming limit diagram
September 2007
Defects in formed parts
T. Udomphol
www.bgprecision.com
Springback problem
~ 55o for an isotropic
material in pure tension
Edge condition
 u  2n
Localised necking in a strip in tension
Suranaree University of Technology
Crack near punch & shoulder
September 2007
Introduction to metal forming
aluminium.matter.org.uk
T. Udomphol
Earing in drawn can
•Radial crack
•Surface blemish (orange peel)
•Wrinkling
Stretcher strain in low-carbon steel.
Suranaree University of Technology
•Mechanical fibering
September 2007
Processing route
T. Udomphol
Tool geometry
-Die
-Punch
-Blankholder
-Drawbeads
-Spacers
Material characteristics
-Stress-strain curve
-Directionality
-Forming criteria
-Young’s modulus
-Friction
Process parameters
-Process steps
-Blank outline
-Blankholder pressure
-Blankholder stiffness
-Stress relief cuts
-Sheet gauge
-Drawbeads
-Friction
Forming simulation
Forming
Result
www.thefabricator.com
Suranaree University of Technology
September 2007
References
T. Udomphol
• Dieter, G.E., Mechanical metallurgy, SI metric Edition, 1988, McGraw-Hill,
ISBN 0-07-100406-8
• Edwards, L. and Endean, M., Manufacturing with material, 1998,
Butterworth Heinemann, ISBN 0 7506 2754 9.
• Beddoes, J. and Bibbly M.J., Principles of metal manufacturing process,
1999, Arnold, ISBN 0-470-35241-8.
• Lange, K., Handbook of metal forming, 1985, R.R Donnelly & Sons
Company, ISBN 0-07-036285-8.
•Lecture notes, Sheffield University, 2003.
•Lecture notes, Birmingham University, 2003.
•Lecture notes, Metal forming processes, Prof Manus Satirajinda.
Suranaree University of Technology
September 2007