Manufacturing Process of an Automobile Component

8/10/2019 Manufacturing Process of an Automobile Component

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INTRODUCTION

Forging process may be defined as a metal working process by which metals or

alloys are plastically deformed to the desired shape by a compressive force applied with thehelp of a pair of dies. One die is stationary and the other has a linear motion .Forging process

can be carried out both in cold and hot state of the metal. But, unless otherwise mentioned,

forging process is considered to be “hot forging process”.

Forging improves the quality of steel, which becomes stronger after forging. ue to

this, the parts which are sub!ected to heavy duty are generally made of forging. "ime of

production is very often reduced. #uch less steel is consumed in forging operation. $ence

the cost of any given part is reduced. %n forge shops, steel is received as ingots or as rolled

sections. %ngots are used for manufacturing heavy forgings while rolled billets are used for

lighter forgings. Forgings, which have to undergo subsequent machining, are called &blanks'.

"hose which do not need any further machining are called &finished' forgings.

Forgings may be produced in either open or close dies. %n open die forging is also

known as “flat die forging”, the hot metal is struck or pressed between two flat surfaces or

simple contoured dies. "he compressive force is progressively applied locally on different

parts of the metal shock. "he flow of metal, that is, the changing of its dimensions and shape

is controlled with the aid of various blacksmiths tools.

%n closed die forging process, cavities or impressions are cut in the die Block, the

compressive force is applied to the entire surface and the metal is forced to take its final

shape and dimensions as it flows into and fills the die cavities. "he flow of metal is limited

by the surfaces of the recesses or cavities in the dies. (hen the pair of dies approaches each

other for completing the forging, the e)cess, metal squirts out of the cavity as a thin ribbon of metal called “flash”. Because of flash, the term “closed *die forging” is a bit of misnomer.

+losed *die forging means no flash .so, a better description of the process with

recesses or cavities in the die blocks would be “%mpression *die forging”.

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Open *dies are less costly than impression dies and so are used where number of

components, to be forged is too small to !ustify the cost of impression dies, or where the

sies are too large and too irregular to be contained in usual impression dies, Open *die

forging can be used for simple shapes only such as -Bars ,slabs or billets with rectangular

,circular ,he)agonal ,or octagonal cross sections, welder rings, and many other components

of simple shapes. On the other hand, for more comple) and accurate parts and with increased

production rates, impression dies are preferred.

%n open die forging, the weight range of forging goes up to few tonnes, whereas in

impressions die forging, the weight range is limited up to few hundred ewton due to

limitation of die sie. %n open die forging, the forgings are usually made on hydraulic presses

designed for forging ingots, where as impression die forgings are made on hammers or

presses/mechanical 0hydraulic1.Open die forgings are required for heavy equipment and

machinery such as for steel plants, power generation ,shipping and defense where as

impression die forgings are generally used in automobile sector. %n open die forging, the

simplicity of tooling is gained at the e)pense of the comple)ity of process control, where as

in impression die forging, the process is simplified to a sequence of simple compression

strokes at the e)pense of comple) die shape.

CHARATERISTICS OF CLOSED –DIE FORGINGS

+losed die forgings have the following characteristics.

2. 3aving of time as compared to open *die forging.

4. #akes good utiliation of work piece material.

5. 6)cellent productivity with good dimensional accuracy.

7. Forgings are made with similar machining allowances, thus reducing considerably the

machining time and the consumption of metal required for the forging.

8. Forgings of complicated shapes can be made.

9. "he equipment for closed:die forging does not require highly skilled workers.

;. "he grain flow of the metal can be controlled ensuring high mechanical properties.

<. #ethod is suited for rapid production rate

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=. +ost of the tooling is high, therefore, suitable for large production areas.

CLASSIFICATION OF DIES

"he dies used for closed:die forging or impression:die forging may be classified in to

two groups.

(i)SINGLE IMPRESSION DIE:

"his die contains only one cavity or impression, which is the finishing impression.

"he preliminary forging operations are done by hand or on forge hammers, forging rolls etc,

and only final finishing operation is done on the cavity.

(ii)MULTI IMPRESSION DIE:

"his die contains finishing operation and one or more au)iliary impressions for

preliminary forging operations. "he final shape of the part is progressively developed over a

series of steps from one die impression to the ne)t. >enerally multi:impression dies are very

e)pensive to make and are employed only when the quantity to be made is sufficient large,

and for forging of intricate designs.

ADVANTAGES OF MULTI-IMPRESSION DIE

2. +omplete sequence of forging operations can be carried out on single equipment only,

avoiding the use of au)iliary equipment.

4. ?se of multi:impression dies is suited for production of small and medium sied forgings

in large quantities as this method gives 4to5 times the production compared with the method

of production using a single die. "his is because the time of production of the &use' on

au)iliary equipment is reduced or eliminated.

5. @ll the preliminary operations can be performed on these dies with good ease. "he &use'

can be prepared to fairly accurate dimensions. Besides this more accurate forgings can be

prepared.

7. (astage of forging metal is reduced

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8. ?se may not be reheated for the finishing impression.

9. %nitial die cost becomes insignificant in case of high output.

;. Finishing impression lasts long, because, much of the load is taken by blocking impression.

THE IMPORTANCE OF THREE-DIMENSIONAL GEOMETRY

6arly +@ systems were basically automated drafting systems, which displayed a

two:dimensional representation of the ob!ect being designed. Operators /e.g., the designer or

drafter1 could use these graphics systems to develop the line drawing the way they wanted it

and then obtain a very high quality paper plot of the drawing. By using these systems, the

drafting process could be accomplished in less time, and the productivity of the designers

could be improved.

$owever, there was a fundamental shortcoming of these early systems. @lthough they

are able to reproduce high:quality engineering drawings effectively and quickly, these

systems stored in their data files a two:dimensional record of drawings. "he drawings were

usually a three:dimensional ob!ects and it was left to the human beings who read these

drawings to interpret the three:dimensional shape from the two:dimensional representation.

"he early +@ systems were not capable of interpreting the three:dimensionality of the

ob!ect. %t was left to the user of the system to make certain that the two dimensional

representation was correct as stored in the data files.

#ore recent computer : aided design systems posses the capability to define the

ob!ects in three:dimensions. "his is a powerful feature because it allows the designer to

develop a full three:dimensional model of an ob!ect in the computer rather than the two

dimensional illustration.

"he computer can then generate the orthogonal views, perspective drawings, and

close:ups of details in the ob!ect. "he importance of this three:dimensional capability in

interactive computer graphics should not be underestimated. %t is important that the graphics

system work with three dimensional shapes in developing the model of the ob!ect.

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FLANGE YOKE:

Flange yoke is a component used in propeller shaft of the automobiles. %t is a component,

which is used for the transfer of power from the engine of the vehicle to the rear wheels. "he

universal !oint allows driving power to be carried through two shafts that are at an angle to

each other. "he universal !oint is a doubled hinged !oint consisting of two flange yokes and a

cross:shaped member called the spider. One of the yokes is on the driving shaft and the other

on the driven shaft. "he four arms of the spider called trunnions are assembled into bearings

in the end of the two shaft yokes. "he driving shaft and yoke cause the spider to rotate. "he

other two trunnions of the spider cause the driven shaft to rotate. (hen the two shafts are at

an angle to each other, the bearings in the flange yoke permit the yokes to swing around on

the trunnions with each revolution.

5



FORGING DIE DESIGN

Before designing the tools to produce a given forging, the shape of the final forging

has to be determined. "here are certain underlying principles for achieving a practical and

economical forging design. "he tool engineer must have a clear understanding of these

principles or factors, which are discussed below-

1. DRAFT:

%t is the angle of taper put on all sides of the forging to facilitate its quick removal

from the die cavity after forging. %n case of drop forging and press forging,

e)ternal

draft

internal

draft

the usual values of draft angle are- 5A to ;A for e)ternal surface 8A to 2CA for

internal surfaces.

%f automatic e!ection devices are employed to free the forging from the die cavity, the

draft angle can be reduced to 2A. raft is appreciably lowered in case of forging

machine since the stock is firmly held by gripping dies. %t is some times as small as

2D4A

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2. FILLET AND CORNER RADII:

@ fillet means the rounding of the ape) of an internal angle and corner radius means

the rounding of the ape) of the e)ternal angle. 3harp edges on the body of the forging

and hence the die cavity increases the tendency towards forging defects and

accelerates die wear. @lso sharp edges will hinder the complete filling of the die

cavities. "herefore, generous fillet and corner radii are the most desirable features of a

closed : de forging because it assists the flow of hot metal and eliminates the

possibility of forging laps or shuts. @lso, the premature die failures due to stress

cracks and abrasions are prevented. $ence, larger the fillet and corner radii, longer

will be the die life and better will be the forging quality. "he usual values of fillet and

corner radii are given in table-

3. PARTING LINE:

"he parting line is the line along the forging where the two halves of a pair of forging

dies meet. %t divides the die impression into two parts from which one is made in the

top die and the other in the lower die. "he shape and location of the parting line is

very %mportant as these have considerable influence on the flow of metal, die cost anddraft requirements, etc. regarding the location of the parting line, the die designer

should always remember the fundamental factor that in forging, the metals flows

much more easily in the lateral direction /path of least resistance1 than in the direction

of applied force. "hus in forging process, it is easier to spread metal than to force it

into deep die impression. 3o in most forgings the parting line is at the largest cross *

section of the part. @nother fundamental factor is that the metal fills the top die first,

so the deep and intricate of the impression should be cut in the top die. (hen owing

to the shape of the forging, a complete impression is arrived at in on part of the dieE

this should be the top die. %n such a case the lower die remains without the impression

and will have only locating elements to secure the proper location of the forging.

@nother factor in the selection of parting line is that should avoid deeper die

impressions to minimie die wear. eeper die impressions would require high forging

pressure for complete filing and might lead to die breakage. @ proper parting line may

eliminate the chances of grain flow reversal and improve the mechanical properties. @

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parting line, which may not require any additional draft provided for easy removal of

forging from die, will result in large savings in machining cost and raw material.

. SHRINKAGE AND DIE !EAR:

Before forging, the work material is heated to the forging temperature. uring the

forging operation, it is in the process of cooling and consequently shrinking. "o take

into account the e)pansion of the material at high forging temperature, the die cavities

are made corresponding larger by using a shrink scale. For steel, this allowance is

about29mm per meter.

ie to continuous useE the dimensions of the die do not remain the same. ie wear is

the difference in dimensions, which occurs due to abrasion of the die impression. "his

is accounted for in the forging design as follows-

For forgings weighing up to about 78 , the die wear allowance is taken as C.7 to C.<

mm for e)ternal as well as for internal surfaces. For forgings weighing from =C to 448

the allowance may increase from 2.9 mm to 4.7 mm.

". MISMATCH:

%n closed die forging it is very difficult to achieve perfect alignment of the two die

halves and either the upper or the lower die may shift during forging. "his shift may

occur sideways or endways. "he forging produced by shifted die will be mismatch.

"he mismatch should be avoided amount of permissible mismatch is given in the

table.

#. FINISH ALLO!ANCE:

3ome forged parts require surface condition or accuracy, which may not be possible to

obtain during forging. For this, the parts will have to be subsequently machined. For

this purpose e)tra material is provided on the forging which may vary from C.< mm to

5.4 mm depending upon the material and relative sie of the forging.

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$. DIMENSIONAL TOLERANCES:

"hese are the variations permitted from the given or normal dimensions and these

may include thickness tolerances and length tolerance. +ommercial tolerance for

thickness are as given below.

%. !E&S AND RI&S:

@ web is usually the thinnest portion of a forging. %t will cool first and when it goes

below the forging temperature, the forging pressure required increase rapidly. 3o,

webs less than about 7.;7 mm thick are not usually practical. "he ribs should be

proportionately low and wide. "heir height should not be more than < times the width.

"he minimum recommended rib thickness is equal to that for webs.

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DIE MANUFACTURE

Below, discuss the various methods /conventional and latest1 for cutting impression in the

die * blocks.

MECHANICAL MACHINING PROCESS:

"hese are the most commonly used methods for manufacturing dies. "he processes include-

turning, machining on planer, milling and grinding.

TURNING i' used for cough and finish machining of rotary working surface, whereas for

rectangular and square die * blocks, these operations are done on a PLANNER .

GRINDING is mainly used for finishing the surfaces.

"he impressions are cut in the die block by highly skilled men who use the MILLING

MACHINE, specially designed for sinking dies.

+utters of various types are used in accordance with the shape of each section of the

impression. But much of the accuracy of the die depends upon handwork performed after it is

sunk. "he impressions are machined either by manual sinking after layout aDor by copy

milling using templates or patterns.

%n copy milling, the following variations in the process are available. #anual copy milling,

where the feed of spindle is controlled by hand. 3emi automatic copy milling, where the feed

in the longitudinal and lateral a)es is automated but the vertical movement is controlled

manually. @utomatic copy milling, where the movement of the cutting tool is controlled

automatically by the movement of a sensor over the surface of a 5 pattern. "his method can

produce intricate surfaces economically on both small and large dies.

DIE SINKING STEP:

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$oles are drilled in the sides of the die blocks opposite each other. $andling bars may be

inserted in these holes. "his facilities case in lifting and handling heavy die blocks.

e)t, the shanks for the attachment of the dies in the forging hammer or press are machined

on a planner.

2. e)t, the die blocks are turned over the bed of the planer and the striking surfaces

are machined to obtain clean and sound metal for the impressions which are to be

sunk.

4. "he die blocks are then squared which facilitate e)act alignment of the die blocks

when placed in the forming hammer or press.

5. LAYING OUT THE OUTLINE OF THE IMPRESSIONS: #etal templates are made from

the blue print or model of the part to be forged. "hese templates are then used for

laying out the outline of the impressions, which are to be sunk in the die blocks. %n

the absence of a template, the layout is made from the forging or die drawing. "he

faces of the die blocks are given a color back ground by coating them with copper

sulphate or a similar purpose solution, to secure a convenient surface for the marking

of the outline of the impression.

7. MACHINE !ORK : "he first impression to be sunk is the finishing impression. %f the

impressions are of simple shape, they are sunk on vertical milling machines, those of

intricate shapes are machined on die sinkers.

8. &ENCH !ORK : @fter sinking the impression, the hand work on the bench includes

operation such as scraping, filling, grinding and polishing the cavities. "he finishing

impression must be true for every dimension. "hey must be lapped and polished free

of all tool marks and sharp corners, so that the impressions will allow the metal to

move with least resistance in filling the cavities of the dies.

9. PREPARATION OF LEAD COST: @fter the finishing impression has been completed,

the die blocks are clamped together in e)act alignment. @ lead antimony alloy is

poured in the finishing impression through a sprue, which is machined into each die

block from its outer edge and e)tends to the cavity of the finishing impression. "he

resulting lead cast or “proof” is now carefully checked for dimensional accuracy by

the die maker, as well as by the engineer. "he lead cast may also be checked by the

producer and the user of the forgings, before final approval for release for production

is obtained. 3ince steel shrinks on cooling from its forging temperature and the lead

alloy does not, it is necessary to allow for the shrinkage in checking the lead cast.

11



;. @fter lead cast has been approved, the sinking of the other impressions is begun. "he

ne)t impression to be sunk is the blocking impression. "he rolling or edging

impression can ne)t be sunk into the die block and so on.

<. "he flash may begin to form at the blocking impression, but most of it will develop

at the finishing impression where the full impact of the hammer blows or full

pressure of press is utilied to the utmost. "hus, the blocking impressions are seldom

flashed or guttered, whereas the finishing impressions usually flashed in both sides,

and guttered, only in the top die. By flashing both dies, we get a neater and more

symmetrical appearance of the final forging. By guttering the top die only, the

forging will sit flush in the trimming die which must be used to trim the e)cess flash.

#achining of the flash gutter will complete the necessary machining work required

for a given set of forging dies.

Flash must be thin to aid die filling and produce close tolerances. %t also acts as

“safety valve” for e)cess metal.

@ thin flash running out between parallel die surfaces would lead to very large

length D thickness ratios and thus to high die pressures. "herefore, the length of flash

is reduced by cutting a “flash gutter”. "his allows free flow of the flash and limits the

minimum flash thickness to only a small width. "he width of the flash “flash land” is

given as,

Flash land 5 to 8h, wide

=. Gastly, the die is given a final dressing to fillet all sharp corners at the flash line to

permit ease of metal flow.

2C. #any dies are now surfaces treated for improved were resistance, by techniques

similar to those described for metal cutting tools.

N*+i,/ C0+0* Mii4:

"his technology is gaining importance due to the reduced time needed for making

dies. $owever, the application of this technology depends on the availability of a

numerical description of the die geometry and on the development of punched tapes.

For machining surfaces of relatively simple analytical description such as cylinders,

cones, spheres and second order surfaces, problem oriented programming languages

12



such as @H" /automatic programmed tools1 and 6I@H" /e)tension of @H"1 have been

developed. "hese permit programming the cutter paths required to machine the entire

surface by means of a few appropriate instructions. "he instructions are processed with

the help of processing programs /processor and post processor1 using a suitable

computer. +omple) surfaces may be described by using suitable mathematical surface

models generated directly by +@ or indirectly by digitiing from technical drawings or

from measurements made on 5 models.

Liii0' 05 ,06/ ii4 NC ii4:

%n addition of the limitation set by the relationship between the shape to be machined

and the cutting tool as well as by the tolerance requirements, another limit is set by the

fact that the shaft diameter and the tip radius of the sensor /stylus1 following the pattern

cannot be infinitely small because of probing forces involved. "herefore, die cavities

with sharp small corner radii can not be machined easily by milling. "he critical limit is

given by the loading of the cutting tool. %t is reached when materials with strength of

greater than 25CC #Ha are machined. "he machining of dies in the annealed state, where

the material strength is ;CC to <CC #Ha, raises the performance of these milling methods

considerably and should be preferred.

E.D.M: 6lectro ischarge #achining /6#1 is an electro:thermal non:traditional

machining process, where electrical energy is used to generate electrical spark and

material removal mainly occurs due to thermal energy of the spark.

6# is mainly used to machine difficult:to:machine materials and high strength

temperature resistant alloys. 6# can be used to machine difficult geometries in small

batches or even on !ob:shop basis. (ork material to be machined by 6# has to be

electrically conductive. %n 6#, a potential difference is applied between the tool and

work piece. Both the tool and the work material are to be conductors of electricity. "he

tool and the work material are immersed in a dielectric medium. >enerally kerosene or

deionised water is used as the dielectric medium. @ gap is maintained between the tool

and the work piece. epending upon the applied potential difference and the gap

between the tool and work piece, an electric field would be established. >enerally the

tool is connected to the negative terminal of the generator and the work piece is

connected to positive terminal. @s the electric field is established between the tool and

the !ob, the free electrons on the tool are sub!ected to electrostatic forces. %f the work

13



function or the bonding energy of the electrons is less, electrons would be emitted from

the tool /assuming it to be connected to the negative terminal1. 3uch emission of

electrons are called or termed as cold emission. "he “cold emitted” electrons are then

accelerated towards the !ob through the dielectric medium. @s they gain velocity and

energy, and start moving towards the !ob, there would be collisions between the

electrons and dielectric molecules. 3uch collision may result in ionisation of the

dielectric molecule depending upon the work function or ionisation energy of the

dielectric molecule and the energy of the electron. "hus, as the electrons get accelerated,

more positive ions and electrons would get generated due to collisions. "his cyclic

process would increase the concentration of electrons and ions in the dielectric medium

between the tool and the !ob at the spark gap.

"he concentration would be so high that the matter e)isting in that channel could be

characterised as “plasma”. "he electrical resistance of such plasma channel would be

very less. "hus all of a sudden, a large number of electrons will flow from the tool to the

!ob and ions from the !ob to the tool. "his is called avalanche motion of electrons. 3uch

movement of electrons and ions can be visually seen as a spark. "hus the electrical

energy is dissipated as the thermal energy of the spark.

"he high speed electrons then impinge on the !ob and ions on the tool. "he kinetic

energy of the electrons and ions on impact with the surface of the !ob and tool

respectively would be converted into thermal energy or heat flu). 3uch intense localised

heat flu) leads to e)treme instantaneous confined rise in temperature which would be in

e)cess of 2C,CCCo+.

3uch localised e)treme rise in temperature leads to material removal. #aterial removal

occurs due to instant vaporisation of the material as well as due to melting. "he molten

metal is not removed completely but only partially.

@s the potential difference is withdrawn as the plasma channel is no longer sustained. @s

the plasma channel collapse, it generates pressure or shock waves, which evacuates the

molten material forming a crater of removed material around the site of the spark.

"hus to summarise, the material removal in 6# mainly occurs due to formation of

shock waves as the plasma channel collapse owing to discontinuation of applied

potential difference.

>enerally the work piece is made positive and the tool negative. $ence, the electrons

strike the !ob leading to crater formation due to high temperature and melting and

material removal. 3imilarly, the positive ions impinge on the tool leading to tool wear.

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DIE - DESIGN OF AN FLANGE YOKE

@s already noted the dies are made in sets of halves. One : half the die is attached to the ram

and the other stationary anvil. "he die halves may be having one or more than one

impressions. %n single impression dies, die impression is the finishing impressionE the

preliminary forging operations are done on other machines such as forging roles, up setter

and benders etc. #ulti *impression dies may have two /blocking and finishing1 or more than

two impressions. %n these dies the final shape of the forging is progressively developed over a

series of steps from one die impression to the ne)t. 6ach impression gradually distributes the

flow of metal and changes the shape of work : piece as it is transferred from one impression

to ne)t between strokes.

"he art of forging die design aims at determining the minimum number of steps the lead from

the starting material /usually a round or rectangular bar1 to the finishes shape.

For a multi:impression die the preliminary forging operations or the perform operations that

are usually required in shaping the part is generally classified as-

2. Fullering or swaging

4. 6dging or rolling

5. Bending

7. rawing down or drawing out or cogging

8. Flattening

9. Blocking

"he other operations on such a die are-

;. Finishing operation

<. +ut off

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"he forging operations that are required in shaping the FG@>6JOK6 are

2. B?3"6L

4. BGO+K%>

5. F%%3$%> OH6L@"%O

1. &USTER:

"his is usually the first operation performed on the heated rectangular bar. "he basic

function of this operation is that it moves the various parts of the stock in to a proper relation

with shape of the finishing impression where such a section is of non:symmetrical in section.

%n these die the bottom die half is flat and the top die half contains the ribs shape of the flange

yoke. "he gap between the top die half and the bottom die half is maintained as 4Cmm.@ draft

angle of 8 degrees is maintained at the corners of the top die so that the component is easily

removed from the die cavity ."o the inner edges, fillet of radius 28mm is given.

One blow is generally required for this operation.

2. &LOCKING:

Blocking impression or the blocker also called, as “semi:finishing impression” is the

streamlined model of the finishing impression and required on some types of forging for one

or both the general reasons. "he first and the more important reason is that the finishing

impression may contain too many obstructions in the form of depressions, holes, bosses,

plugs or abrupt contours or section changes, to permit a normal flow of metal to all parts of

the impression without further preparations from the preceding operations. "he blocking

impression has the general shape of the finishing impression. "he blocking impression has

the general shape of the finishing impression but with all the corners, holes and abrupt section

changes thoroughly rounded so that plastic metal may be moved into suitable position for

16



more e)act cshaping the finishing operation. Blocking impression aids in prevention of the

forging defects such as cold shuts.

3econd reasons for the use of blocking impression are to reduce the wear of the finishing

impression. 6)cessive wear of the finishing impression reduces the useful die life. %n case of

certain forgings, which are symmetrical in shape, the blocking impression is only a

preparatory impression. %n blocking impression, the length and width smaller, the height or

thickness is more, but the center distance is the same as in the final impression. "he

difference may be 2to 4 mm on each side, but higher clearance of 5 to 8mm can be

recommended where partial displacement of metal occurs. For flange yoke the difference is

taken as 8mm.

One blow is generally required for blocking operations.

3. Fii'7i4 I6+*''i0:

"his impression represents the e)act shape of the finished forging. "he shape and sie

of the finishing impression is checked in the process of manufacture of die by plaster of Haris

or lead cast. "he finishing impression is located in the middle of the die block but it is notnecessarily in its central a)is. $owever, it is vital to locate the final impression in such a

manner that there will be no horiontal forces that give a side thrust and make as die shaft. %t

is this advisable to have the loud center of forging directly below the a)is of ram.

F'7 ,*+

"he flow of plastic metal under the blows of the drop banner or the pressure of

forging press, proceeds first to fill up the finishing impression and then a small quantity of

the e)tra metal moves into shallow cavity provided a round the finishing impression of the

die. "hese small cavities which are directly outside the die impression are known as flash

gutter. "he flash gutter is separated from the die impression by narrow passage, which is the

flash land. "he volume of the flash land and the flash gutter should be about 4CM to 48M of

the volume forging.

"he amount of e)cess metal from the finishing impression may be too large to permit

the complete closing of the dies. "he gutter is provided to ensure complete closing of the die.%t acts as storage for the e)cess material after it is passed through the flash land. "oo large a

17



gutter reduces the striking area for the die surfaces. @lternatively, too small a gutter will

result in e)trusion of flash between the striking surfaces of the die, resulting in an oversie

forging

"he dimensions of the gutter may be taken from the table given below-

3tock sie, mm >utter "hickness imensions, mm.

(idth

?pto 5< 5.4 48.7

5< to 8C 7.< 48.7 to 52.;8

8C to 95.8 7.< 52.;8 to 5<

;9 to 2CC 9.7 5< to 77.8

CUT OFF

(hen the forging are made from the bar stock, they are must be cut off after the

forging operation is completed. "his is done either by special side cutter of the trimming

press or by the cut if impression milled usually in the left back corner of the die block or by a

trimming designed for the purpose.

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HOT FORGING PROCESS OF FLANGE YOKE

".1 RA! MATERIAL INSPECTION:

"he material is inspected by general tests like-

2. Nisual inspection

4. 3park testing

5. 3pectral testing

7. +hemical analysis

8. $ardness testing

9. #acro e)aminations

;. #icro e)aminations

<. >rain sie

=. %nclusion rating

2C. ?psetting testing

22. >as content analysis

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"he raw material used in manufacturing of automobile flange yoke is 5;c28.%t

generally contains C.5;M carbon and 2.8M manganese and other chemical properties,

raw material is shown in the above fig.

(hether raw material is within limits /as mentioned by customer1 they usually

prefer for better inspection as here they used spectral analysis.

"he spectral analysis consists of a spectrum machine which is capable of

showing around 29 elements present in the raw material.

%t is usually tested by the concept of emission of wave and calculating the

content of elements.

"he gas used in this spectrum machine is inert gas.

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"he machine used here is #6"@N%3%O * 2C<

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".2 CUTTING SECTION:

"he raw material which is in round or rectangular bars with a huge length is passed

into this cutting section as to cut in required lengths. ?sually to cut that bars we use band saw

machine or shearing machine and nowadays ++ machines.

".3 FORGING SECTION:

"he raw material is passed into the furnace as the hot forging indicates working above

the recrystalisation temperature but below boiling point. ?sually the furnaces used are oil

type, induction type. "he hot bar is placed in press forging or drop hammer containing top

die and bottom die. (hen the ram blows the bar then the metal takes shape of a die.

epending upon the component the die contains buster, blocker, and finisher.

". INSPECTION:

THE VERNIER CALLIPER

"he principle of vernier is that when two scales or divisions slightly different in sie

are used, the difference between they can be utilised to enhance the accuracy if measurement.

"he vernier caliper essentially consists of two steel rules and these can slide along each other.

One of the scales, i.e., main scale is engraved on a solid G:shaped frame .On these scale cm

graduations are divided into 4C parts so that one small division equals C.C8 cm. One end of

the frame contains a fi)ed !aw which is shaped into a contact tip at its e)tremity.

VERNIER HEIGHT GAUGE

#ost 3uitable for tool room and quality control applications. #anufacturing areas

with fine ad!ustment.

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3tainless 3teel $olding Brackets.

Geast +ount C.C4 mm.

3cale made from 3tainless 3teel.

Lemovable +arbide "ipped Hoint.

Leading Faces are ull +hrome.

DEPTH GAUGE

9P 3teel Lule with $ardened and >round 3teel Base.

3pring tension ut for easy depth measurement.

>raduated in inches and mm.

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SURFACE MARKING &LOCK 8 GAUGES (R0 &'*)

3turdy construction surface gage.

+onsists of @d!usting knob and hardened scriber.

Lound base made of close grain +ast %ron.

Nery useful for every workshop.

FINAL INSPECTION:

GAUGES are inspection tools of rigid design, without a scale, which serve to check

the dimensions of manufactured parts. >auges do not indicate the actual value of the

inspected dimension on the work. "hey can only be used for determining as to whether the

inspected parts are made within the specified limits. >auges usually used for checking are

plug gauges for checking holes, snap and ring gauges for checking shafts.

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"." HEAT TREATMENT

TYPES OF HEAT TREATMENT:

Four basic types of heat treatment are used today. "hey are normaliing, hardening,

and tempering. "he techniques used in each process and how they relate to 3teelworkers are

given in the following

NORMALI9ING:

ormaliing is a type of heat treatment applicable to ferrous metals only. %t differs

from annealing in that the metal is heated to a higher temperature and then removed from the

furnace for air cooling. "he purpose of normaliing is to remove the internal stresses induced

by heat treating, welding, casting, forging, forming, or machining. %t is frequently applied as

the final heat treatment process on items which are sub!ected to relatively high stresses.

?sually, low:carbon steels do not require ormaliingE however, if these steels are

normalied, no harmful effects result. %t usually heated at temperature of <9CQ7CAc and held

there for a specified period.

HARDENING:

"he hardening treatment for most steels consists of heating the steel to a set

temperature and then cooling it rapidly by plunging it into oil, water, or brine. #ost steels

require rapid cooling /quenching1 for hardening but a few can be air:cooled with the same

results. $ardening increases the hardness and strength of the steel, but makes it less ductile.

>enerally, the harder the steel, the more brittle it becomes. "o remove some of the brittleness,

you should temper the steel after hardening. #any nonferrous metals can be hardened and

their strength increased by controlled heating and rapid cooling. %n this case, the process is

called heat treatment, rather than hardening. "o harden steel, you cool the metal rapidly after

thoroughly soaking it at a temperature slightly above its upper critical point. "he addition of

alloys to steel decreases the cooling rate required to produce hardness. @ decrease in the

cooling rate is an advantage, since it lessens the danger of cracking and warping.

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Hure iron, wrought iron, and e)tremely low:carbon steels have very little hardening

properties and are difficult to harden by heat treatment. +ast iron has limited capabilities for

hardening. (hen you cool cast iron rapidly, it forms white iron, which is hard and brittle.

@nd when you cool it slowly, it forms gray iron, which %s soft but brittle under impact.

TEMPERING:

@fter the hardening treatment is applied, steel is often harder than needed and is too

brittle for most practical uses. @lso, severe internal stresses are set up during the rapid

cooling from the hardening temperature. "o relieve the internal stresses and reduce

brittleness, you should temper the steel after it is hardened. "empering consists of heating the

steel to a specific temperature /below its hardening temperature1, holding it at that

temperature for the required length of time, and then cooling it, usually instill air. "he

resultant strength, hardness, and ductility depend on the temperature to which the steel is

heated during the tempering process. "he purpose of tempering is to reduce the brittleness

imparted by hardening and to produce definite physical Hroperties within the steel. "empering

always follows, never precedes, the hardening operation. Besides reducing brittleness,

tempering softens the steel. "hat is unavoidable, and the amount of hardness that is lostdepends on the temperature that the steel is heated to during the tempering process. "hat is

true of all steels e)cept high:speed steel.

UENCHING MEDIA:

"he cooling rate of an ob!ect depends on many things. "he sie, composition, and

initial temperature of the part and final properties are the deciding factors in selecting the

quenching medium. @ quenching medium must cool the metal at a rate rapid enough to

produce the desired results. #ass affects quenching in that as the mass increases, the time

required for complete cooling also increases. 6ven though parts are the same sie, those

containing holes or recesses cool more rapidly than solid ob!ects. "he composition of the

metal determines the ma)imum cooling rate possible without the danger of cracking or

warping. "his critical cooling rate, in turn, influences the choice of the quenching medium.

"he cooling rate of any quenching medium varies with its temperatureE therefore, to getuniform results, you must keep the temperature within prescribed limits.

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HARDNESS is a property of material which is defined as the resistance to penetration,

abrasion, scratch cutting etc. "he hardness is usually calculated by Brinell hardness test after

hardening, normaliing, tempering.

&RINELL HARDNESS TEST- "his determines the resistance of a material to penetration.

$ardness is determined by measuring the impression made by steel ball forced into specimen

under a predetermined load. %t has got only one scale of hardness and Brinell hardness

number is defined as the average a)ial stress over the surface of the indentation produced by

the steel ball, assuming the indented surface is spherical. "he advantage of Brinell hardness

test is that it has got direct relations with ma)imum tensile strength of the material. "he

diameter of the spherical impression is measured by a high magnification microscope and the

spherical area calculated from the diameter of impression and diameter of ball. "he surface to

be tested must be smooth and free from surface defects.

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CONCLUSION

"he die design plays vital role in designing a component. "he solid models of automobile

components like flange yoke have been created with help of an @?"O+@ and other modern

software's. "hese are the similar process involved in manufacturing of any automobile

component. $ot forging process is generally employed for main automobile components.

epending up on component sie and shape the forging section is done. "he initial inspection

is main method to check the errors. @fter forging process the component is sent here to check

all the primary errors like change in length and height, width and other errors. %f we found

any error the component is not further processed, if there is no error it is sent to ne)t section

that is heat treatment. @fter heat treatment it is sent to the crack detection method to found

cracks in the component. +old coining process, it is very important section. %t is used to

eliminate bending in the component, it makes component straight. @nd at last final inspection

is done. @nd finally to dispatch.

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REFERENCE

1. PRODUCTION TECHNOLOGY &Y R. K. ;AIN

Documents

Manufacturing Process of an Automobile Component