new concepts in die design — physical and computer modeling applications

New concepts in die design Ð physical andcomputer modeling applications

Victor Vazquez*, Taylan Altan

ERC for Net Shape Manufacturing, Ohio State University, Columbus,

OH 43210, USA

Abstract

The application of Computer Aided Engineering and physical modeling techniques in forging R & D continues to increase. In using tools

such as Finite Element Modeling and experiments with model materials, the forging tool designer can decrease costs by improving

achievable tolerances, increasing tool life, predicting and preventing ¯ow defects, and predicting part properties. At the Engineering

Research Center for Net Shape Manufacturing, Design Environment for Forming (DEFORM) and DEFORM 3D, and a multiple action

press for physical modeling are tools available for forging research and for educational purposes.

This paper summarizes the results of industrially relevant `̀ work-in-progress'' research with numerical and physical modeling systems.

Current projects include: a tool design for the forging of a cross groove inner race for a constant velocity joint, and the design of a tooling to

forge a connecting rod without ¯ash. # 2000 Elsevier Science S.A. All rights reserved.

Keywords: Physical modeling; Cold forging; Process modeling

1. Introduction

In research and development of forging processes the use

of process simulation programs and physical modeling

techniques is complementary. By using these tools the

forging tool designer could decrease costs by improving

achievable tolerances, increasing tool life, predicting and

preventing ¯ow defects, and predicting part properties.

In most cases numerical models provide more ¯exibility

in the analysis of the metal ¯ow than physical models

since they allow for quick changes in the tooling design

and its motion. On the other hand, physical modeling

helps the designer to visualize problems with the process

and the tooling that may arise during the tryout of the actual

tooling.

This paper summarizes some current research projects at

the engineering research center for net shape manufacturing

(ERC/NSM) which use both physical modeling and process

simulation. These include tool design of a cross groove inner

race for a constant velocity joint and a die for ¯ashless

forging of a connecting rod.

2. Design of forging process and tooling aided bycomputer and physical modeling

In general forging entails the sequential deformation

of the workpiece material through a number of different

processes [1]. Furthermore, each forging operation com-

prises all the input variables such as billet material,

dies, the conditions at the die-workpiece interface, the

mechanics of shape change in the workzone, and the

characteristics of the processing equipment, as illustrated

in Fig. 1 [2].

The main objectives of the physical and numerical mod-

eling for the design in forging processes are:

1. To develop adequate die design and establish process

parameters:

� to assure die fill,

� to prevent flow induced defects such as laps and cold

shuts,

� to predict processing limits that should not be

exceeded so that internal and surface defects are

avoided,

� to predict temperatures so that part properties, friction

conditions and die life can be controlled (only numer-

ical modeling).

Journal of Materials Processing Technology 98 (2000) 212±223

* Corresponding author. Tel.: �1-614-688-3461; fax: �1-292-5874.

0924-0136/00/$ ± see front matter # 2000 Elsevier Science S.A. All rights reserved.

PII: S 0 9 2 4 - 0 1 3 6 ( 9 9 ) 0 0 2 0 2 - 2

2. To improve part quality and complexity while reducing

manufacturing costs by:

� predicting and improving microstructure and grain

flow (only numerical modeling),

� reducing die try-out and lead times,

� reducing rejects and improving material yield.

The steps involved in integrated product and process

design for forging are schematically illustrated in Fig. 2.

Based on functional requirements, the geometry (shape,

size, surface ®nish, tolerances) and the material are selected

for a part at the design stage. Then design rules and

experience are used to determine a preliminary design.

The modeling stage is needed to verify the design and make

appropriate modi®cations to the tooling and the process.

Once the process has been veri®ed several times the tooling

is manufactured and the tryout phase begins. It is expected

that through the use of modeling the number of changes after

tryout would be less than through the conventional design

procedures.

2.1. Physical modeling

In general physical modeling involves the use of non-

metallic model materials like plasticine or wax, which can

be deformed easily and could be used to study and predict

the deformation of metals. To obtain a reliable material ¯ow

the friction conditions at the tool-workpiece interface for the

model must be very similar to the actual process. Thus, the

selection of the lubricant is critical for the success of the

modeling effort.

Physical modeling has several advantages like:

� Material flow is very close to actual forging operations,

� Forging loads could be estimated by dynamic similarity,

� Several preform designs could be evaluated in short time

to obtain the optimum metal flow,

� A physical model is available for demonstration and

discussion purposes,

� The forming of very complex parts could be evaluated in

shorter time than with 3D finite element method (FEM)

simulations.

However, also physical modeling has the following lim-

itations:

� It is difficult to estimate the contact stresses on the

tooling,

� Temperature effects, such as die chilling, cannot be taken

into account,

� Production of layered billets (for better visualization of

metal flow) is time consuming,

� Conventional measurement of the samples is difficult due

to the softness of the modeling materials,

� Investment in tooling and forming equipment with

enough load capacity is required.

2.2. Computer modeling

Computer modeling is widely used in industry for the

simulation of forging processes. This is mainly due to the

Fig. 1. Variables of a bulk forming process [2].

Fig. 2. Product and process design for net shape manufacturing.

V. Vazquez, T. Altan / Journal of Materials Processing Technology 98 (2000) 212±223 213

low cost of the simulations compared to actual tryouts. The

main advantage is the ¯exibility of the systems to make

changes when a problem occurs or the load capacity is

exceeded. Although 2D computer simulations are faster than

3D simulations, the last ones are becoming more practical

with the use of new computers.

Several issues, such as material properties, geometry

representation, computing time, and remeshing capability,

must be considered in cost effective and reliable application

of numerical process modeling.

Several commercial codes are available for numerical

simulation of forging processes; such as DEFORM, and

DEFORM 3D. The accurate and ef®cient use of metal ¯ow

simulations require not only a reliable FE solver [3], but

also:

1. software packages for (a) interactive pre-processing to

provide the user with control over the initial geometry,

mesh generation and the input data, (b) automated

remeshing to allow the simulation to continue when the

distortion of the old mesh is excessive, and (c)

interactive post-processing that provide more advanced

data analysis, such as point tracking and ¯ow line

calculation.

2. appropriate input data describing (a) thermal and

physical properties of die and billet material, (b) heat

transfer and friction at the die-workpiece interface under

the processing conditions being investigated, and (c)

flow behavior of the deforming material at the relatively

large strains that occur in practical metal forming

operations.

3. analysis capabilities that are able to (a) perform the

process simulation with rigid dies to reduce calculation

time, and (b) use contact stresses and temperature

distribution from the process simulation with rigid dies

to perform elastic plastic die stress analysis.

The time required to run a simulation varies depending on

the computer used, its memory, and its workload. However,

with today computers it is possible to run a complex 2D

forging simulation in a few hours, while a 3D simulation

would take from several hours to several days to be com-

pleted [4].

3. Process design to cold forge a cross groove inner racefor a constant velocity joint

Many complex automotive parts, like the cross groove

inner race (CGIR) for a constant velocity joint (see Fig. 3),

have asymmetric geometric features and undercuts. In the

case of the CGIR traditional cold forging methods are not

capable of producing such part. The cost to make the CGIR

is often relatively high because broaching is used to make

the grooves, this is a time consuming process. However, a

multi-action cold forging process could be used to reduce the

manufacturing cost of the CGIR.

3.1. Cross groove constant velocity joint

The cross groove CV joint is an improvement of the

Rzeppa CV joint, which consists of inner and outer races, six

balls, and a cage between the inner and outer races. The six

balls are maintained in the intermediate plane by means of

the cage (see Fig. 3).

The cross groove CV joint allows relative axial displace-

ments of the shafts (plunging: in some cases up to 48 mm).

The grooves of the outer and inner race cross at an angle of

�32.48 to get this effect. This results in a reduction of

vibration and noise, a signi®cant reduction in joint size, and

an increase in the maximum speed and torque. This design

offers the most mass ef®cient CV joint, i.e. the joint has the

least mass for the same functionality compared to other

joints, and it has a wide application [5].

3.2. Manufacturing of cross groove inner race

The common steps to manufacture the inner race are:

� peeling of bar to control the volume,

� billet sawing from a cold drawn bar,

� cold forging,

� broaching of the grooves,

� induction hardening or carbonizing of the grooves

depending on the type of steel that is used [6].

The inner races for other types of CV ball joints are

almost entirely made by cold forging [7±9], which is a very

Fig. 3. An example of a cross groove universal joint [6].

214 V. Vazquez, T. Altan / Journal of Materials Processing Technology 98 (2000) 212±223

cost-effective process. Therefore, by changing the process

from machining to cold forging several machining opera-

tions could be reduced resulting in a lower manufacturing

cost.

The advantages of cold forging the CGIR are:

� faster process, because the forming time takes only a few

seconds,

� cheaper, because the high production rate of a forging

press eliminates the expensive tooling and time consum-

ing process required for machining.

The disadvantages are:

� cold forging multi-action tools are expensive,

� forging pressures are large in the die cavity and may

damage the tool.

A small number of advanced companies in Japan, includ-

ing Toyota [10] and more recently, Aikoku Alpha [9], have

begun to produce the inner race by cold forging with multi-

ple-action tooling.

The grooves must be very accurate for the proper opera-

tion of the CV joint, and they must be produced to at least

near-net shape so that only one grinding operation is needed

to ®nish the part.

3.3. Tooling concept

The cold forging of the cross groove inner race is very

dif®cult, because the grooves of the inner race act as under-

cuts. This makes ejection of the part in the conventional

manner impossible. To eject the part, the die must be split

into several die segments. These die segments must be

withdrawn radially.

A design was selected from a number of conceptual

designs for investigation, which were developed based on

the patent search and literature review [11]. This concept

uses six die segments, which move radially. Fig. 4 shows the

selected conceptual design, where the die segments are

brought together around the billet by a conical ring. The

billet is then extruded radially by the counter-acting

punches. After deformation, the punches and the die seg-

ments retract and the formed workpiece is taken out of the

die. In this investigation a `̀ two-body'' punch design pro-

vides the following alternative punch motions:

� Punch variation 1: Stage (1) inner punch performs a

backward extrusion, and Stage (2) inner punch retracts

and the outer punch finish the radial extrusion of the

grooves.

� Punch variation 2: Stage (1) the inner punch performs a

backward extrusion, and Stage (2) the inner punch

remains in position while the outer punch moves

against the billet and finish the radial extrusion of the

grooves.

� Punch variation 3: both punches (inner and outer) move

against the billet at the same speed (like one punch).

The main concerns in cold forging are the magnitude of

the forging pressure on the surface of the die and is the ®lling

of the cavity. It is obvious that the ®rst two punch variations

would result in lower loads than variation 3. However, this

last punch motion should result in better ®lling of the cavity.

Therefore, a compromise must be met between the load

requirements, the ®lling of the cavity and the complexity of

the tooling.

3.4. Physical modeling experiments

A series of 3D physical modeling experiments with

plasticine were performed for each of the alternative tool

designs. The tools for the experiments were based on the

conceptual design shown in Fig. 4 and the ERC/NSM multi-

action servo press (Fig. 5). The ERC/NSM press already

gives two movements in the vertical direction created by two

individually controlled AC servomotors. The additional

motions of the press were achieved through the use of

two pneumatic cylinders that are used to actuate the inner

punches. The cylinders were designed to ride, with the outer

Fig. 4. Cross sectional view of the tooling concept with two-body punch.


punches, on the ball screws powered by servomotors. This

allowed the option of moving both inner and outer punches

together as one, or moving them one after the other. This

press was developed speci®cally for physical modeling of

multi-action forging [12].

3.4.1. Preparation of the plasticine billets

Plasticine is commonly used for physical modeling

experiments, this is a speci®c type of modeling clay. The

plasticine is homogenized and de-gassed by mixing and

extruding it with a two-screw vacuum extruder [6].

In order to investigate the ¯ow of the billet material during

forging it is necessary to construct layered billets. The

construction of the layered billets involves the following

steps:

1. plasticine sheets of two colors are rolled with a

conventional pasta machine,

2. the sheets sit for a day to relieve residual stresses caused

by rolling,

3. the sheets are stacked alternating colors using a thin mist

of acetone to bond them,

4. the stack of sheets sits for several hours,

5. stamp the billets out with a tool similar to a cookie-

cutter.

3.4.2. Physical modeling experiments

The lubrication applied on the tool surface is a mixture of

glycerin and liquid soap. The billet was placed in the die

cavity between the two inner punches, surrounded by the six

punch segments (Fig. 6). Fig. 7 shows the ®nal plasticine

part for all three variations in punch movement. Punch

variation 3 shows the best ®ll but also exhibits the most

¯ash in between the die segments.

As seen in Fig. 7, there are areas in the part that do not ®ll

completely for punch variations 1 and 2. The adequate ®lling

Fig. 5. ERC Multi-Action Press with physical modeling tooling for the

cross groove inner race.

Fig. 6. Half of a layered specimen of the cross groove inner race.

Fig. 7. Final cross groove inner race from plasticine; (left: punch variation

3; center: punch variation 2; right: punch variation 1).


of the cavity depends on the initial billet size, the punch

travel and the friction conditions.

3.5. 2D finite element method simulations

Using a simpli®ed geometry, 2D FEM simulations of the

forming operation were performed with DEFORM. The

speci®ed billet dimensions were as follows:

Diameter 44 mm

Height 30.25 mm

Material AISI 1055

For this simulation the simpli®ed axisymmetric cavity

was ®lled completely. The material used for modeling was

AISI 1050 (�� 971:5�"0:16 N=mm2).

In punch variation 3 (one body punch variation) the

inner and outer punches move together as a single punch.

The ®ll is complete with ¯ash occurring between the die

segments and around the punches, especially in the case

where the plasticine billet was slightly oversized (see Fig. 8).

In this case the ¯ow-net for the 2D simulations matches the

material ¯ow observed in the physical modeling experi-

ments.

3.6. 3D FEM simulations

3D FEM simulations were performed in order to obtain

more accurate predictions for the metal ¯ow, strains, and the

contact pressure distribution between the billet and the die.

The third punch variation was used for this simulations since

it is the one that gives the best ®lling and requires less

complexity in the design of the tooling. DEFORM 3D was

used for these simulations.

Due to symmetry of the cross groove only one sixth

of the billet must be analyzed. The billet was modeled

initially with 4500 tetrahedral elements and 1300 nodes.

The number of elements increased during the remeshing

steps, performed because of the large amount of mesh

distortion occurring in the simulation. The remeshing was

done automatically.

The billet had a plastic material formulation. The tools

were simulated using rigid surfaces. Therefore, tool de¯ec-

tion was not considered. The symmetry condition was

simulated with a plane rigid surface at 608 with respect

to XY plane. The cold forging process was simulated under

the conditions shown in Table 1.

Fig. 9 shows the material ¯ow obtained for the cold

forging operation. It can be seen that the ®lling at the edge

corners of the grooves is not very good. However, during

operation the bearing balls will only have contact with the

middle of the groove, thus, this ®lling problems will not

affect the CGIR's performance.

Fig. 8. Punch variation 3, plasticine and 2D FEM results. Part is sectioned

between the grooves.

Table 1

Process conditions for 3D FEM simulations.

Parameter Value

Velocity of inner and ring punches 100 mm/s

Stroke 14.1 mm

Material AISI-1045

Workpiece temperature 208CSimulation mode Isothermal

Shear friction factor 0.1 (constant)

Fig. 9. Metal flow for the 3D simulation of the cold forging of the CGIR

by the passive die process.

Fig. 10. Tooling with segmented die and tapered ring.


3.6.1. Active versus passive die design

The forging process simulated initially is known as the

passive die design because the conical ring clamps the

segments at the beginning of the process and the active

tools are the punches.

A new process has been proposed in which the die moves

against the billet to form the part [13]. This is achieved by

dividing the forging process in two forging sequences. In the

®rst process a backward extrusion operation to form the

center hole is followed by free upsetting of the workpiece,

this is similar to a pierce upsetting operation. Then the

preform is positioned in between two counter punches and

the tapered ring shown in Fig. 10 moves the segments

against the workpiece to form the ®nal part. In this case a

signi®cant reduction in the forging load is achieved as shown

in Fig. 11. Thus a longer tooling life could be expected. A

tapered ring is preferred to a conical ring because the bearing

surface between segments and die is larger and would assure

a longer life for this tooling component.

4. Tool and process design for flashless forging of aconnecting rod

The design of ¯ashless forging processes is more complex

than the design of conventional closed die forging with ¯ash.

The FEM and the physical modeling techniques offer the

possibility to accelerate the development of the manufactur-

ing process as well as to reduce the development costs

associated with the design of the entire manufacturing

process. In addition, it is possible to perform several itera-

tions to modify the process parameters to determine the best

manufacturing conditions for a forged product.

4.1. Forging of connecting rods

The closed die forging process is often used to manu-

facture high quality mass production parts like connecting

rods, crankshafts, etc., at moderate costs. A sketch of a

closed-die forging process with ¯ash is shown on the left in

Fig. 12. The upper and lower dies form the closed cavity; the

¯ash originates in the gap between the dies. A major

advantage of the closed-die forging with ¯ash is that the

volume of the preform may vary within a relatively large

range, which makes it easier to continuously manufacture

products with the same quality. However, a trimming pro-

cess is necessary to remove the existing ¯ash.

As shown on the right in Fig. 12 ¯ashless forging does not

allow the material to leave the cavity and therefore no ¯ash is

generated. One of the most important advantages of this

process is that a signi®cant amount of material could be

saved in comparison to forging with ¯ash. Furthermore, a

trimming operation is not required.

There are some requirements to get a successful ¯ashless-

forging process:

1. The volume of the initial preform and the volume of the

cavity at the end of the process must be the same,

2. the mass distribution and positioning of the preform

must be such that there will not be local excess or

shortage of material,

3. In the case that the die design has features to

compensate for variations in the volume of the preforms

the actual cavity must be filled first.

4.2. Physical modeling applied to preform design

Before 3D FEM simulations were practical, physical

modeling experiments and 2D FEM simulations were used

[14] to de®ne a preform for the ¯ashless forging of a

connecting rod. 3D FEM simulations of the ¯ashless forging

of a connecting rod were attempted [15] but were unsuccess-

ful due to limitations in remeshing.

4.2.1. Physical modeling experiments

Physical modeling experiments were performed for the

¯ashless forging of a connecting rod using plasticine billets

Fig. 11. Load±stroke curve for active and passive dies and punch variation

3.

Fig. 12. Closed-die forging with and without flash.


and aluminum tooling (see Fig. 13) [14]. The experiments

were performed with the ERC ®ve ton multi-action press

(see Fig. 5). The main objective of the plasticine experi-

ments was to ®nd a preform geometry that would result in

complete ®lling of the die cavity.

The volume distribution in the connecting rod was

obtained by cutting several transverse sections and comput-

ing the area of each one. These values are plotted in Fig. 14

as the cross section area versus the length of the connecting

rod. The area under the curve represents the volume dis-

tribution of the ®nal shape of the connecting rod. Based on

these results an axisymmetric preform was designed. The

preform suggested in [14] is shown in Fig. 15. This preform

was modi®ed based on the physical modeling experiments.

The ®nal plasticine preform and connecting rod are shown in

Fig. 16 (Preform I).

4.3. 3D FEM simulation of flashless forging process

In order to verify the applicability of the new FEM code

DEFORM 3D to the optimization of the preform design, a

simulation of the real connecting rod was performed using

Preform I as de®ned in previous studies [14,15].

An upsetting step of the initial preform had to be carried

out to start the whole forging process, because the pin end of

the initial preform was too big to ®t into the die cavity. This

operation is performed at hot forging temperature.

The upsetting process is simulated using one ¯at die

(constructed by square shell elements) that moves in the

negative Y (down) direction to compress the pin end of the

connecting rod. Tetrahedral 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 2.

Fig. 17 shows the ®nal shape of the preform after upset-

ting. Very little deformation occurred at the I-beam section

and crank end of the preform. The force required to 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 ¯ashless forging was carried out

using one upper punch, one die, and the previously deformed

preform as shown in Fig. 18.

The material ¯ow of the connecting rod forging process is

shown in Fig. 19. Fig. 20 shows the contact condition

between the crank end portion of the billet and the tooling

at the end of the forging. It can be seen from this ®gure that a

relatively large cavity remains at the upper surface of the

crank journal ring (marked as * in Fig. 20). The I-beam

section is formed from the ends, thus the metal ¯ow for this

section is not under plane strain.

It was concluded from these results that to optimize the

initial geometry of the preform the following problems have

to solved [16]:

Fig. 13. Aluminum tooling for physical modeling of flashless forging of

connecting rod.

Fig. 14. Axisymmetric plasticine preform.

Fig. 15. Sketch of Preform I of the connecting rod.

Fig. 16. Plasticine preform and connecting rod [3].


1. For the crank end section, it is necessary to redesign the

preform so that it ®lls the cavity completely and

uniformly.

2. For the pin end section, it is necessary to control the

initial volume distribution and transfer the excessive

volume to other features of the product.

3. For the I-beam section, it is required to determine the

diameter for which plane strain flow could be achieved.

4.4. Optimization of the preform geometry

It would be very dif®cult to optimize the whole geometry

of the preform at once, since the preform shape is relatively

complex and has a lot of shape parameters as shown in Fig.

15. Hence, the workpiece was divided into three sections:

crank end section, pin end section, and I-beam section. Each

section was optimized independently. This optimization

procedure was adopted for the following reasons [16]:

� Since the connecting section is deformed nearly in plane

strain conditions, it is assumed that the deformation of the

large end section and that of small end section do not

strongly interfere with each other.

� The number of shape parameters is reduced and the

optimization process becomes easy to handle.

� Simulation time is reduced by working with a smaller

model.

The seven shape parameters for the crank end were

reduced to three independent parameters and four dependent

parameters. Three preform designs were selected from the

combinations of parameters.

The top view of the material ¯ow for the crank end

preforms is shown in Fig. 21. The shaded area indicates

contact between the billet and the tools. It is clear that the

selection of the geometrical parameters affect signi®cantly

the metal ¯ow.

Similarly for the pin end three preforms were de®ned. The

top view of the ®nal shape achieved for each preform is

shown in Fig. 22. The deformation pattern of the pin end is

not sensitive to the initial geometry of the preform because it

is completely formed before the forging process for the

whole connecting rod is completed.

There are three parameters in the connecting I-beam

section: diameter d3 and segment lengths s4 and s5, as

shown in Fig. 15. The area of a cross section of the I-beam

part calculated by I-DEAS was 42.637 mm2. Hence, assum-

Fig. 17. Effective strain distribution after upsetting.

Table 2

Input data for the upsetting process

Simulation parameter

Billet material Al 2618

Punch velocity 20 mm/s

Stroke 4.5 mm

Simulation mode Isothermal

Simulation steps (NSTEP) 90

Fig. 18. Model for the forging of a connecting rod.

Fig. 19. Material flow in forging of the connecting rod.


ing that the material of this part is ¯ows under plane strain

conditions the initial diameter d3 of the connecting I-beam

section was set to 7.37 mm.

4.5. FE simulation with the optimized preform

Evaluating the results obtained from the optimization

method, a new preform design is proposed (Preform II),

shown in Fig. 23. A second 3D FEM simulation was

performed with this preform design, and was compared

with the earlier results. The dimensions of the new preform

are shown in Table 3.

The material ¯ow of the connecting rod forging process

with Preform II is shown in Fig. 24. The pin end section is

formed completely, the I-beam section ¯ows nearly under

plane strain conditions, and the crank end section is ®lled

Fig. 20. Contact condition with the tools at the crank end section. �:

contact, *: no contact.

Fig. 21. Material flow for the preforms defined for the optimization of the crank end.

Fig. 22. Final stage deformed billets of the pin end section in top view (XY

plane).


almost completely. It was concluded that fair results may be

obtained with the design for Preform II.

4.6. Manufacturing the preform

The preform suggested in the previous section could be

manufactured by cross rolling. However, variations in the

cross-rolling process may affect the required dimensions of

the initial preform for the ¯ashless forging process. In order

to verify these points, further investigations of the 3D FEM

simulation or physical modeling experiments are needed.

5. Conclusions and future work

In the case studies presented in this paper it has been

shown that physical and numerical modeling are helpful in

the current design practices of forging processes due to the

following reasons:

� these techniques are generally cheaper than performing

tryout with actual dies and equipment,

� modifications to the tooling model (CAD design or soft

tooling) are cheaper and less time consuming than mod-

ifications of the actual production tooling and equipment,

� modeling provides more information about the process

like: load requirements and metal flow at different stages

of the process,

� for most applications result may be obtained faster from

modeling than from actual tryouts.

The future work for the CGIR should be focused on the

following issues:

� Evaluation of a tool design for physical modeling with

full motion capabilities as the tooling to be used for

production.

Fig. 23. Comparison of the shape parameters of Preform II with that of

Preform I.

Table 3

Shape parameters of preform-II, mm

s1 s2 s3 s4 s5 s6 s7 s8 d1 d2 d3 d4 d5

14.50 6.82 20.18 18.50 13.50 7.19 7.11 4.70 9.00 20.00 7.37 15.75 7.00

Fig. 24. Material flow of the forging simulation with Preform II.


� Stress analysis of the tooling to assure the expected

performance [13].

The future work related to the design of ¯ashless forging

processes should involve the following aspects:

� Flashless forging results should be compared with results

obtained from forging with flash. This would help to

determine more clearly the advantages and disadvantages

of flashless forging.

� Tool stress analysis of the tooling must be performed in

order to analyze the best way to achieve the longest tool

life with the highest accuracy.

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Process Research Committee, I. Finnie (Chair), National Academy

Press, 1995.

[3] M. Knoerr, J. Lee, T. Altan, Application of the 2D FEM to simulation

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