Investigation of metal flow and preform optimization in flashless forging of a connecting rod

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Journal of Materials Processing Technology 59 (1996) 95-105

Materials
Processing
Technology

Investigation of metal flow and preform optimization
in flashless forging of a connecting rod
T e r u i e T a k e m a s u a, V i c t o r V a z q u e z b'', B r e t t P a i n t e r b, T a y l a n A l t a n b

aMechanical Engineering for Intelligent Machinery and Systems, Kyushu University, Japan
bERC for Net Shape Manufacturing, The Ohio State University, Columbus, OH 43210, USA
Industrial Summary

In conventional hot forging of connecting rods, the material wasted to the flash accounts approximately 20
to 40% of the original workpiece. In order to reduce the cost of forged products, the forging must be performed in
a closed cavity to obtain near-net or net shape parts. In flashless forging, the volume distribution of t h e
preform must be accurately controlled to avoid overloading the dies and to fill the cavity. Additionally, t h e
preform must be simple enough to be mass produced.
This study deals with the design of the optimum preform to forge a connecting rod without flash. The
initial preform design was obtained from physical modeling experiments. The optimization of this preform
was found through 3D FEM process simulations. The advantage of performing simulations is that no tooling
has to be built and the number of experimental tryouts can be significantly reduced. A preform optimization
methodology was derived for this investigation.
1. Introduction

If the weight of a connecting rod (see Fig. 1) can

be reduced while increasing its strength, an
automobile's fuel efficiency will be improved.
Currently, steel connecting rods are used in passenger
cars. However, some manufacturers have attempted
to use alternative lighter materials. Recently,
various composite materials based cn aluminum
have been considered, but not yet successfully
adopted, for automotive engines. The main reasons
are that these materials are not strong enough, or
when strong enough, are too expensive.
Flashless forging offers the possibility of
producing aluminum composite connecting rods at
competitive costs. The design of flashless forging
processes is more complex than the design of
conventional closed die forging with flash.
Therefore, in order to accelerate the development of
the manufacturing process as well as to reduce t h e
development costs, a new design method must be
developed and applied. The Finite Element Method
(FEM) offers the possibility to design the entire
manufacturing process on a computer. This leads to a
"Corresponding author
0924-0136/96/$15.00 © 1996 Elsevier Science S.A. All rights reserved
PI10924-0136 (96) 02290-X

reduction of the cost and time in process and tool
design, tool manufacturing, and die try-out. In
addition, it is possible to iteratively modify t h e
process conditions in the simulation to find the best
manufacturing conditions for a product.

Fig. 1: Connecting rod

1.1 Forging of Connecting Rods
The closed die forging process is often used to
manufacture high quality mass production parts like
connecting rods, crankshafts, etc., at moderate costs.
In principle, forging operations are non-steady state


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7q Takemasu et al. / Journal of Materials Processing Technology 59 (1996) 95-105

processes, in which the deformation of the m a t e r i a l
takes place under three-dimensional stress and
strain conditions. The material flow depends
mainly on the following [1]:
a) Geometry of the cavity
b) Geometry of the flash opening
c) Initial and intermediate billet geometry
d) Percentage of flash
e) Heat transfer between the tooling and t h e
billet
A sketch of a closed-die forging process w i t h
flash is shown c~a the left in Fig. 2. The upper and
lower dies form the closed cavity; the f l a s h
originates in the gap between the dies. A major
advantage of the closed-die forging with flash is
that the volume of the preform can vary within a

specific range, which makes it easier to continuously
manufacture products with the same quality.
However, a trimming process is necessary to remove
the existing flash.
As shown on the right in Fig. 2 flashless forging
does not allow the material to leave the cavity and
therefore no flash is generated. One of the most
important advantages of this process is that a
significant amount of material can be saved in
comparison to forging with flash. Furthermore, a
trimming operation is not required.
There are some requirements to get a successful
flashless-forging process:
a)The volume of the initial preform and t h e
volume of the cavity at the end of the process
must be the same.
b) There must be neither a local volume excess
nor a shortage, which means that the mass
distribution and positioning of the preform
must be very exact.
c) If there is a compensation space in the dies,
the real cavity must be filled first.
1.2 Research Objectives

So far, most FE codes that simulate billet forming
processes consider only plane-strain or axisymmetric
deformations. Since many industrial parts such as
connecting rods have very complex geometries, t h e
metal flow is three-dimensional and cannot be
properly modeled with

a two-dimensional
approximation. This means that
a threedimensional simulation of the manufacturing process
must be performed to get adequate results. The
commercial package DEFORM 3D v.2.015] offers t h e
possibility
of
simulating
three-dimensional
material flow of complex geometries.
The 3-D FEM simulation of the flashless forging
of a connecting rod has already been performed a t
the ERC/NSM with DEFORM-3D v.l.0 [2].

However, it was not possible to simulate the whole
forging process due to the limited remeshing
capabilities of DEFORM 3D v.l.0. Therefore, it was
not possible to verify that the preform designed
from physical modeling experiments [3] was indeed
the optimum preform. Due to the improved
remeshing capabilities of the recently released
DEFORM 3D v.2.0, it is now practical to optimize
the preform shape through the analysis of the FEM
simulation results.
Forging with
Flash

Flashless FOrs~ngwith
Forging

Up
Die

Flashless
Forging
Forging

Bilh

F l a ~

L~~'l
;

' Lower
Punch
Start of Stroke

End of Stroke

Fig. 2: Closed-die forging with and without flash
The objectives of this study are:
i) perform the 3-D FEM analysis of an actual
connecting rod with DEFORM 3D v.2.0 using
the preform defined in the previous studies
and find out the problems in the design of the
preform.
ii) optimize the preform design in each region
independently, that is, large end section,
connecting section, and small end section.

iii) define a new preform design based cn t h e
optimization
results
and
verify
the
applicability of this optimization method.
2. Previous Studies in Preform Optimization

Before 3D FEM simulations were practical,
physical modeling experiments and 2D FEM
simulations were used [3] to define a preform for t h e
flashless forging of a connecting rod. 3D FEM
simulations of the flashless forging of a connecting
rod were attempted [2] but were unsuccessful due to
limitations in remeshing.
2. ] Physical Modeling Experiments

In metal forming operations, in order to predict
metal flow, die filling, defect occurrence, and


T. Takeraasu et al. / Journal of Materials Processing Technology 59 (1996) 95-105

forming loads, the use of highly deformable model
materials represents a valid and powerful tool.
In the tool design phase, a soft material, either
metallic or non-metallic, can be used to carry out
several tests by changing the tooling geometry. The
aim is to optimize material flow and die filling

using machinable tools and low cost die materials
(i.e. acrylic, glass or aluminum). Furthermore,
compared
to hot
forging
processes, lower
temperatures are typically used in modeling tests.
Physical modeling experiments were performed
for the flashless forging of a connecting rod using
plasticine billets and an aluminum tooling [3]. The
experiments were performed c~ the ERC five ton
multi-action press. The main objective of t h e
plasticine experiments was to find a preform
geometry that w o u l d result in complete filling of the
die cavity.
The volume distribution in the connecting rod was
obtained by cutting several transverse sections and
computing the area of each. These values were
plotted in Fig. 3 as the height versus the length of
the connecting rod. The area under the curve,
indicated by the arrow "A', represents the volume
distribution of the piece. Based c~ these results an
axisymmetric preform was designed. The preform
suggested in [3] is shown in Fig. 4. This preform was
modified based cn the
physical
modeling
experiments. The final plasticine preform and
connecting rod are shown in Figure 5.
2.2 3D FEM Process Simulation of a Connecting Rod

3D FEM analysis of the flashless forging of
connecting rods was performed with two different
types of preform geometries [2], which were called
(1) real geometry and (2) simplified geometry.

A

I

i
Fig. 3: Connecting rod volume distribution versus
length

•

97

.................. i I ~

Fig. 4: Axisymmetric plasticine preform

Fig. 5: Plasticine preform and connecting rod [3].
The shape of the real connecting rod is a
modification of a Nissan connecting rod. Isometric
views of the real and a simplified connecting rod are
shown in Fig. 6. The simplified geometry of t h e
connecting rod was used
to
verify

how
simplifications, made in order to accelerate t h e
simulation process, affect the simulation results.
These 3D FEM simulations used brick elements for
the billet and rigid surfaces to model the tooling.
The software used was DEFORM 3D vl.0. The
simulations were run isothermally. The main
limitation of the code used was that it did not h a v e
automatic remeshing capabilities. Therefore, t h e
remeshing had to be performed semi-automatically
by approximating the deformed shape of the b i l l e t
with surfaces and remeshing the enclosed volume
with tetrahedrals which were latter broken into
bricks. Since this is a a time consuming operation i t
was only possible to achieve 75% of the stroke for
both geometries. The effective strain in t h e
deformed connecting rod is shown in Fig. 7.

3. Preform Optimization by 3D FEM Simulation
In order to verify the applicability of the new
FEM code DEFORM 3D (v2.0), a simulation of t h e


98

T Takemasuet al. / Journal of Materials Processing Technology 39 (1996) 95-105

real connecting rod was performed using preform-I as
defined in previous studies [2,3]. A sketch of
preform-I is shown in Fig. 8.

3.1. F E Simulation o f the Forging Process

An upsetting step of the initial preform had to be
carried out to start the whole forging process,
because the smaller end of the initial preform was
too big to fit into the die cavity. This operation is
performed at hot forging temperature.

form half of the workpiece is almost 1.9 metric tons,
this means that 3.8 metric tons are required for this
operation.
The simulation of the flashless forging was
carried out using one upper punch and one die w i t h
the upsetted preform in between as shown in Fig. 11.
Before the upset preform was imported into t h e
forging simulation, a remeshing was executed to
make meshes finer especially at the smaller end
section.

1.240
1.13o

1.010
0.896
0.781

~

0.665
O.550

0.435
0.319

~

0.204
0.089

Fig. 7: Effective Strain Distribution
S1

sl
3.96
s8
4.70

Fig. 6: a) real and b)simplified connecting rod
geometry
The upsetting process is simulated using one f l a t
die (constructed by square shell elements) t h a t
moves in the negative Y (down) direction to compress
the small end of the connecting rod. T e t r a h e d r a l
elements were used for the billet in this simulation.
The simulation was stopped at a stroke of about 1.5
mm. The relevant data for this simulation are
shown in Table 1.
Fig. 9 shows the final shape of the preform after
upsetting. Very little deformation is present in t h e
connecting section and the large end of the preform.
The necessary punch load curve calculated for this

operation is shown in Fig. 10. The force required to

s2
26.77
dl
9.65

$2

s3
12.04
d2
16.76

$3

s4
17.23
d3
7.01

$4

s5
11.61
d4
16.26

$5

s6
6.58
d5
7.06

$6

$7 $8

s7
7.90

Fig. 8: Sketch of preform-I of the connecting rod

l

.J~O

m ,lt~
*000
Fig. 9: Effective strain distribution after upsetting


IT. Takemasu et al. /Journal o f MaterJals Processing Technology 59 (1996) 95-105
i(10 4
1.864

1.553

1.243

Y

0
a

.932

d

(N) .~1
.311

.000

m

#~0

t7~

m
im ~ 5

i
2e2~

l
3eO~

m

3¢7~

m
4t5~(

(ram)

Y-Stroke

Fig. 10: Punch force of preform upsetting process
Punch movement

Fig. 12: Material flow in forging of the connecting
rod.

Fig. 11: Simulation model for the forging of the
connecting rod
Table1: Input data for the upsetting process
Simulation Parameter
Billet material
Punch velocity
Stroke
Simulation mode
Simulation steps (NSTEP)

AI 2618
20 mm/s
4.5 mm
Isothermal
90

The material flow of the connecting rod forging
process is shown in Fig. 12. Fig. 13 shows the contact
condition between the large end portion of the b i l l e t
and the tooling at the end of the forging. It can be
seen from this figure that a relatively large c a v i t y
remains at the upper surface of the bigger ring p a r t
in the large end section (marked as * in Fig. 13). In
the connecting or I-beam section, the side wall was
initially
formed from both ends, gradually
proceeded to the middle and combined together
finally. So the deformation pattern of this section
may not be completely in plane strain and does not
have enough height at the center even at the end of
the stroke.

+: contact
*: no contact
Fig. 13:Contact condition with the tools in the large
end section.

99


100

T Takeraasu et al. / Journal o f Materials Processing Technology 59 (1996) 95-105

It was concluded from these results that to

optimize the initial geometry of the preform we t h e
following problems had to solved:
a) For the large end section, we need to optimize
the preform geometry to fill the cavity
completely and uniformly.
b) For the small end section, control the i n i t i a l
volume distribution of this part and transfer
the excessive volume to other features of t h e
product.
c) For the connecting I-beam section, we need to
optimize the diameter of the preform in order
to deform the side wall nearly in plane strain
conditions.

BT1
d2=20
s1=15
=41.5

,:,T2
d1=22
s1=14
s3=11

3.2 Optimization of the Preform Geometry
It seems very difficult to optimize the w h o l e
geometry of the preform at once, since the preform
shape is relatively complex and has a lot of shape
parameters as shown in Fig. 8. Hence, the workpiece
was divided into three sections: large end section,

small end section, and connecting section. Each
section was
optimized
independently.
This
optimization procedure was adopted for t h e
following reasons:
i) Since the connecting section is deformed nearly
in plane strain conditions, it is assumed t h a t
the deformation of the large end section and
that of small end section do not strongly
interfere with each other.
ii) The number of shape parameters is reduced
and the optimization process becomes easy to
handle.
iii) Simulation time is reduced by working w i t h
a smaller model.

3.2.1

Large End Optimization

There are seven shape parameters in the large
end section (see Fig. 8). In order to reduce the number
of parameters, the diameters dl and d3, the total
volume, and the total length were set to be constant.
The diameters d2, the segment length sl, and t h e
length pl=sl+s2+s3 are selected as independent
parameters. Then the other parameters, that are
segment length s2, s3, and s4, were chosen based on

these constraints (see Fig. 8).
Three preform designs for the large end section
were selected for the FE simulation model from t h e
various combinations of parameters, and are shown
in Fig. 14. They are named BT0, BT1, and BT2
respectively. BT0 is the original preform and is
represented by the dotted line in those figures. The
diameter d2 and the segment length sl of BT1 are
both larger than that of BT0. The length of pl of
BT2 is shorter than that of BT0.

Fig. 14 : Sketch of some preforms for BT1 and BT2

The top views of the material flow of the large
end section for each preform are shown in Fig. 15.
Fully 100% of the stroke was achieved in each
simulation. The shaded area in the top views shows
the contacting area between the surface of the b i l l e t
and the tools.
The outer wall of the bigger ring of BT1 and BT2
is deformed almost radially throughout the forging
process and has sufficient height at the end of t h e
stroke. This is compared to BT0, which is sinked in
at the beginning of the forging process and remains a
little concave even after deformation. As for t h e
side wall next to the connecting section, the cavity is
filled completely in cases BT0 and BT1, while t h a t
of case BT2 is not filled at all. Comparing m a t e r i a l
flow in top views, as the diameter d2 is increased
and the length pl is decreased, the die cavity of t h e

outer wall of the bigger ring is filled more r a p i d l y
and smoothly. This is because the material is
prevented from flowing to the bigger ring part after
the material of the section s3 contacts the die.
It is seen from these results that in order to
deform this large end section successfully, t h e
diameter d2, the segment length sl, and the length
pl have to be selected correctly.

3.2.2

Small End Optimization

Since the small end section was completely
formed before the end of the stroke in the FE
simulation of preform-I, the volume distribution was


T, Takemasu et al. / Journal o f Materials Processing Technology 59 (1996) 9.5-105

.

\

BT0
BT1
Fig. 15: Material flow of the BT0 - top view (XY plane)

varied to optimize the preform geometry. There are
also seven shape parameters in this section(see Fig.

8). The diameters d3 and d5, the segment length s8,
and the length p2=s6+s7+s8 are fixed. The i n i t i a l
volume of this section was controlled by changing
the diameter d4 and the segment length s6.
Three preforms for the small end section were
modeled as shown in Fig. 16. They are called TP1,
TP2, and TP3 respectively. The geometry of t h e
small end section of the preform-I is represented by
the dotted line. The shape parameters of these
preforms are compared in Table 2. The volume of TP1
is the smallest. TP3 has the same volume as TP2, but
the diameter d4 of TP3 is a little larger than that of
TP2. Thus the volume distribution of TP3 is gathered
to the top end relative to TP2.
Table 2: Shape parameters of the small end section

TP1
TP2
TP3

101

volume
mm 3
3082
3250
3250

s7
mm

5.70
7.11
6.27

s8

p2

d4

d5

5.0
5.0
5.0

19.0
19.0
19.0

15.5
15.75
16.0

7.0
7.0
7.0

The top view of the deformed billets at the end of
the stroke are shown in Fig. 17. The small end

sections of TP2 and TP3 are completely deformed,
while in the case of TP1 a cavity remains at the side
wall. From these results, it can be concluded that the
deformation pattern of this part is not sensitive to

BT2

(a) T P 1

(b) T P 2

(c) T P 3

Fig. 16: Sketch of FE models of the small end section


102

T. Takemasu et al. / Journal of Materials Processing Technology 59 ('1996) 95-105

the initial geometry of the preform, since this is
formed by the upsetting process before the complete
forging process.
3.2.3 Connecting I-Beam Section Optimization

There are three parameters in the connecting Ibeam section: diameter d3 and segment lengths s4
and s5, as shown in Fig. 8. The area of a cross section
of the I-beam part calculated by I-DEAS was 42.637
m m z. Hence, assuming that the material of this part
is deformed under plane strain conditions the initial

diameter d3 of the connecting I-beam section was set
to 7.37 ram.
j
Underfilling

preform design, and was compared with the earlier
results. The dimensions of the new preform are
shown in Table 3.
The material flow of the connecting rod forging
process with preform-II is shown in Fig. 19. As one
can see from this figure, the small end section is
formed completely. The connecting I-beam section
flows nearly under plane strain conditions and t h e
side wall has enough height after deformation. The
large end section is deformed almost completely,
although a very slight cavity remains between t h e
billet and the upper punch at the upper surface of
the bigger ring.

(a) TP1

(b) T P 2

z
(c) TP3

Fig. 17: Final stage deformed billets of the small
end section in top view (XY plane)

Fig.18: Sketch of preform-II

3.3 FE Simulation with New Preform

Evaluating the results obtained from the
optimization method, we proposed a new w h o l e
preform design (preform-II), shown in Fig.18. A
second 3D FEM simulation was performed with this

Fig. 19: Material flow of the forging simulation
with preform-II


7~ Takemasu et al. / Journal of Materials Processing Technology 59 (1996) 95-105

103

range between 0.26 and 2.29 at the end of the stroke.
The strain
distribution
of an intermediate
simulation step for this model is comparable to
Mezger's final results [2].
The load predicted for the forging of preform-II
is 30% higher than that of preform-I. This is
because the stroke for preform-II is longer than t h a t
of preform-I and a relatively large cavity is
observed at the upper surface of the bigger ring p a r t
in the large end section of preform-I after
deformation.

.2~5E,01

(b) Preform-II

| ::::

Fig. 20: Deformation condition of the outer wall of
the bigger ring at the final stage.
Table.3: Shape parameters of preform-II, mm
sl

s2

s3

s4

s5

14.50

6.82

20.18

18.50

13.50 7.19

s6

dl

d2

d3

d4

d5

9.00

20.00 7.37

s7

s8

7.11 4.70

15.75 7.00

The deformation condition of the outer wall of
the bigger ring of preform-II at the final stage is
compared with that of preform-I in Fig. 20. The area
pointed to by arrow 1 in preform-II has enough
height and contacts the upper punch, while t h a t
area in preform-I is sinked in and does not contact
the upper punch at all. The areas pointed to by
arrows 2 and 3 in preform-I! are concave because

they reflect the geometrical pattern of the upper
punch, while such geometrical properties are not
observed in similar areas of preform-I. The edge
areas pointed to by arrows 4 and 5 in preform-II look
sharper than that of preform-I. This is because t h e
die cavity of these areas of preform-II is filled
almost completely, while a small cavity can be
observed in the same areas of preform-I. It was
concluded that fair results may be obtained with the
design for preform-II.
Fig. 21 shows the effective strain of t h e
connecting rod in the final stage. The strain values

Fig. 21: Effective strain of preform-II final stage,
a)intermediate step and b) final step.

4. Manufacturing the Preform

In section 3, a new preform design was suggested
and good simulation results were obtained. But there
is still another important problem: that is, how to
manufacture the preform. Each manufacturing
method has its own advantages and disadvantages
concerning tooling cost, lead time, finished shape,
and product tolerances. In this section, the design
and dimensions of the new preform are compared
with those of the old preform and the feasibility of
producing the new preform by cross rolling is
discussed. Furthermore, the flashless forging of a
connecting rod is also compared with the forging of a

connecting rod with flash.


1~ Takemasu et al. / Journal of Materials Processing Technology 59 (1996) 95-105

104

The principle of operation of cross rolling
machines is shown in Fig. 22 [4]. In this process, a
round billet is inserted transversely between two or
three rolls, which rotate in the same direction and
drive the billet. The rolls, which hold replaceable
die segments with appropriate impressions, make
one revolution while the workpiece rotates several
times in the opposite direction. Thus, the cross
rolling method can form axially symmetrical shafts
with complex geometries in one operation.
FLANK

~GE

t.EAD
~'dGLE
KNIFE
GE

REDUCTION AT
POS*TI O~ 2
~ RECTION OF
METAL FLOW

ON flOLL SURFACE

NADIAL
~/

REDUCTION AT
ITION 3

Fig. 22: Principle of operation of cross rolling
machine [4]

5. Conclusions and Future W o r k

The cross rolling machines are suitable for
automatic production, using bar stock automatically
fed to the rolls through an induction heating unit.
Therefore, cross rolling takes advantage of h i g h
productivity (about 900 parts per hour). The design
variables of this process are the lead angle of t h e
wedge, the flank angle, and the amount of reduction.
The disadvantages of cross rolling are that selfcontained machines are expensive and the forming
rolls are difficult to design. This process is also
limited to external surfaces. The most important
problem in using cross rolling for this purpose is t h e
desired shape limitations in the preform design.
At present, cross rolling machines will accept
only bars having a maximum diameter of 35 mm. The
minimum diameter of the product is about 12.5 mm.
The maximum reduction ratio is 75%, and rolled
length of product can be up to 400 mm, depending

upon the reduction required.
The reduction ratio is defined as :
R e d u c t i o n R a t i o - Dmax - Dmin x 100

(1)

Omax

with:

Dma x =
Dmi n =

Fig. 23 compares the dimensions and t h e
reduction ratio of the new preform with those of t h e
old preform. The reduction ratio of preform-II is
63.15 % and that of preform-I 58.17 %. These are
both small enough for the allowable limitation of
the reduction ratio for cross rolling. The minimum
diameters of preform-I and preform-II are much
larger than the desired minimum diameter, and t h e
total lengths of preform-I and preform-II are
smaller than 400 mm. So it seems that the cross
rolling is applicable for making both i n i t i a l
preforms.
In the flashless forging process the volume of t h e
preform must be exactly the same as the finished
part and the mass distribution of the preform must
be exact to fill up the die cavity correctly.
Variations in the cross rolling process may affect the

required dimensions of the initial preform for t h e
flashless forging process. In order to verify these
points, further investigations of the 3D FEM
simulation or physical modeling experiments are
needed. Especially for the forging process of t h e
connecting rods with flash, because this process is
not as strict as the flashless forging process in terms
of the volume distribution of the initial preform.

maximum diameter of the preform
minimum diameter of the preform

The preform design was optimized by dividing
the preform into three parts: small end section,
connecting I-beam section, and large end section.
Simulations were performed independently for each
section.
For the large end section, both the i n i t i a l
geometry and the volume distribution of the preform
was optimized at the same time by changing t h e
position and the diameter of the hill section under a
condition of constant volume. It is concluded from
the simulation results that to optimize the geometry
of this part is more difficult than the small end
section or the connecting I-beam section due to t h e
fact that the product shape of this part is very
complex and the material flow is strongly influenced
by the initial geometry of the preform.
For the small end section, the initial volume
distribution was mainly controlled to fill the die

cavity at the end of the punch stroke. It is also clear
that the deformation pattern of this part is not as
sensitive to the initial geometry of the preform as
the large end section.
The deformation pattern of the connecting I-beam
section approached plane strain conditions by
optimizing the initial diameter of this part. The
ribs of the I-beam were almost filled at the end of
the simulation.


T. Takemasu et al. / Journal o f Materials Processing Technology 59 (1996) 95-105
~I

9o.79

L,

Reduction Ratio = 58.17 %
(a) Preform-I

92.50

o

Reduction

Ratio

= 63.15 %

105

Eight to ten remeshing steps were needed in the
simulation from initial preform to the end of the
stroke. About 1% volume loss is observed after every
remeshing step and the total volume loss reached
about 8%.
The future work related to this project should
involve the following aspects:
i) The results of the connecting rod forging
simulations must be compared with the results
from an experimental investigation of the forging
process to verify the applicability of the new
DEFORM 3D code.
ii)The simulation of the connecting rod forging
process with flash should also be performed to
compare the deformation pattern and the
advantages and disadvantages with the results of
the flashless forging of a connecting rod.

(b) Preform-II

Fig. 23: Comparison of the shape parameters of
preform-II with that of preform-I
Evaluating these results, we proposed a whole
new preform design that was called preform-II and
performed the FEM simulation of the forging of the
connecting rod with it. In this simulation, 99.5%
reduction ratio was achieved and the small end

section was formed completely. The connecting Ibeam section was deformed nearly in plane strain
conditions and the side wall of this part had enough
height after deformation. The large end section was
formed almost completely and the side wall of the
bigger ring part was almost radial. A small cavity
remained between the billet and the upper punch.
These results show the validity of the optimization
method adopted in this report.
The load-stroke curve of preform-II is similar to
that of preform-I in its trend, but the peak load of
preform-II is about 30% higher than that of
preform-I.

6. References

[1] Lange, K. (1985). Handbook of Metal Forming.
McGraw-Hill.
[2]Mezger, J., Sweeney, K., Altan, T. (1994).
Investigation of the 3D CODE: Flashless Forging
of a Connecting Rod. ERC/NSM-B-94-31.
[3] Barcellona, A., Long, K., Altan, T. (1994).
Flashless Forging of a Connecting Rod of an
Aluminium Alloy and a Metal Matrix Composite
(MMC) Material. ERC/NSM-B-94-32.
[4] Altan, T., Boulger, F., Becker, J., Akgerman, N.,
Henning, H.
(1973). Forging Equipment,
Materials, and Practices. Metals and Ceramics
Information Center.
[5] SDRC. (1990). Finite Element Modeling - User's

Guide.
Structural.
DynamicsReseach
Corporation, Milford, Ohio.
[6] Scientific Forming Technologies Corporation.
(1994).DEFORM Version 4.0 User's Manual.
Columbus, OH.