Extrusion Fig Q a Analysis

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ExtrusionExtrusion

By S K MondalCompiled By: S K Mondal Made Easy

ExtrusionThe extrusion process is like squeezing toothpaste out ofa tube.

1 Extrusion 2 Die backer 3 Die4 Billet 5 Dummy block 6 Pressing stem7 Container liner 8 Container body

Compiled By: S K Mondal Made Easy

Direct ExtrusionA solid ram drives the entire billet to and through astationary die and must provide additional power toovercome the frictional resistance between the surface of themoving billet and the confining chamber.


Indirect ExtrusionA hollow ram drives the die back through a stationary,confined billet.

Since no relative motion, friction between the billet andthe chamber is eliminated.


The basic principles of forward and backward cold extrusion using open and closed dies.Compiled By: S K Mondal Made Easy

Impact Extrusion


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Cold extrusion forging


Hooker Method Contd…..


Hydrostatic Extrusion Contd….Thus products can be made that could not otherwise beproduced, and materials can be considered that wouldhave been rejected because of their limited ductility atroom temperature and atmospheric pressure.


Wire Drawing Contd….


Wire Drawing Contd….


Rod and Tube Drawing Contd…

Tube Sinking Fixed Plug Drawing

Floating plug Drawing Moving MandrelCompiled By: S K Mondal Made Easy

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Swaging or kneading Contd…


Extrusion LoadApproximate method (Uniform deformation, no friction) “work – formula”

ln oo

f

AP AA

σ⎛ ⎞

= ⎜ ⎟⎜ ⎟⎝ ⎠

For real conditions

K = extrusion constant.

f⎝ ⎠

ln oo

f

AP KAA

⎛ ⎞= ⎜ ⎟⎜ ⎟

⎝ ⎠

Force required in Wire or Tube drawing

Approximate method (Uniform deformation, no friction) “work – formula”

A⎛ ⎞ln o

ff

AP AA

σ⎛ ⎞

= ⎜ ⎟⎜ ⎟⎝ ⎠

Wire Drawing

ExampleCalculate the drawing load required to obtain 30%reduction in area on a 12 mm diameter copper wire.The following data is given

C l l t th f th l t i t if thCalculate the power of the electric motor if thedrawing speed is 2.3 m/s. Take efficiency of motor is98%.

Compiled By: S K Mondal Made Easy Compiled By: S K Mondal Made Easy

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JWM 2010Assertion (A) : Extrusion speed depends on workmaterial.Reason (R) : High extrusion speed causes cracks inthematerial.(a) Both A and R are individually true and R is the(a) Both A and R are individually true and R is thecorrect explanation of A(b) Both A and R are individually true but R is not thecorrect explanation of A(c) A is true but R is false(d) A is false but R is trueAns. (a)


GATE‐2006In a wire drawing operation, diameter of a steel wireis reduced from 10 mm to 8 mm. The mean flowstress of the material is 400 MPa. The ideal forcerequired for drawing (ignoring friction andredundantwork) isredundantwork) is(a) 4.48 kN (b) 8.97 kN(c) 20.11 kN (d) 31.41 kN

Ans. (b)


GATE‐2001For rigid perfectly‐plastic work material, negligibleinterface friction and no redundant work, thetheoretically maximum possible reduction in thewire drawing operation is(a) 0 36 (b) 0 63(a) 0.36 (b) 0.63(c) 1.00 (d) 2.72

Ans. (b)


GATE‐2003A brass billet is to be extruded from its initialdiameter of 100 mm to a final diameter of 50 mm.The working temperature of 700°C and theextrusion constant is 250 MPa. The force requiredfor extrusion isfor extrusion is(a) 5.44 MN (b) 2.72 MN(c) 1.36 MN (d) 0.36 MN

Ans. (b)


GATE‐1996A wire of 0.1 mm diameter is drawn from a rod of 15mm diameter. Dies giving reductions of 20%, 40%and 80% are available. For minimum error in thefinal size, the number of stages and reduction ateach stage respectivelywould beeach stage respectivelywould be(a) 3 stages and 80% reduction for all three stages(b) 4 stages and 80% reduction for first three stagesfollowed by a finishing stage of 20% reduction(c) 5 stages and reduction of 80%, 80%.40%, 40%, 20%in a sequence(d) none of the above Ans. (b)


GATE‐1994The process of hot extrusion is used to produce(a) Curtain rods made of aluminium(b) Steel pipes/or domestic water supply(c) Stainless steel tubes used in furniture(d) Large she pipes used in city water mains

Ans. (a)


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IES – 2007Which one of the following is the correctstatement?(a) Extrusion is used for the manufacture of seamlesstubes.(b) Extrusion is used for reducing the diameter of round( ) gbars and tubes by rotating dies which open and closerapidly on the work?(c) Extrusion is used to improve fatigue resistance of themetal by setting up compressive stresses on its surface(d) Extrusion comprises pressing the metal inside achamber to force it out by high pressure through anorifice which is shaped to provide the desired from of thefinished part. Ans. (d)Compiled By: S K Mondal Made Easy

IES – 2007Assertion (A): Greater force on the plunger is requiredin case of direct extrusion than indirect one.Reason (R): In case of direct extrusion, the direction ofthe force applied on the plunger and the direction ofthemovement of the extruded metal are the same.(a) Both A and R are individually true and R is the correctexplanation of A(b) Both A and R are individually true but R is not thecorrect explanation of A(c) A is true but R is false(d) A is false but R is true

Ans. (b)Compiled By: S K Mondal Made Easy

IES – 1993Assertion (A): Direct extrusion requires larger forcethan indirect extrusion.Reason (R): In indirect extrusion of cold steel, zincphosphate coating is used.( ) B th A d R i di id ll t d R i th(a) Both A and R are individually true and R is thecorrect explanation of A(b) Both A and R are individually true but R is not thecorrect explanation of A(c) A is true but R is false(d) A is false but R is true


IES – 1994Metal extrusion process is generally used forproducing(a) Uniform solid sections(b) Uniform hollow sections(c) Uniform solid and hollow sections(d) Varying solid and hollow sections.

Ans. (c)


IES – 2009Which one of the following statements is correct?(a) In extrusion process, thicker walls can be obtainedby increasing the forming pressure(b) Extrusion is an ideal process for obtaining rods from

t l h i d itmetal having poor density(c) As compared to roll forming, extruding speed is high(d) Impact extrusion is quite similar to Hooker's processincluding the flow of metal being in the same direction

Ans. ( c)


IES – 1999Which one of the following is the correcttemperature range for hot extrusion of aluminium?(a) 300‐340°C (b) 350‐400°C(c) 430‐480°C (d) 550‐650°C

Ans. (c)


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IES – 2000Consider the following statements:In forward extrusion process

1. The ram and the extruded product travel in the samedirection.

2. The ram and the extruded product travel in the oppositep ppdirection.

3. The speed of travel of the extruded product is same as thatof the ram.

4. The speed of travel of the extruded product is greater thanthat of the ram.

Which of these Statements are correct?(a) 1 and 3 (b) 2 and 3(c) 1 and 4 (d) 2 and 4 Ans. (c)Compiled By: S K Mondal Made Easy

IES – 2009What is themajor problem in hot extrusion?(a) Design of punch (b) Design of die(c) Wear and tear of die (d) Wear of punch

Ans. (b)


IES – 2008Which one of the following methods is used for themanufacture of collapsible tooth‐paste tubes?(a) Impact extrusion (b) Direct extrusion(c) Deep drawing (d) Piercing

Ans. (a)


IES – 2003The extrusion process (s) used for the production oftoothpaste tube is/are1. Tube extrusion2. Forward extrusion3. Impact extrusionSelect the correct answer using the codes given below:Codes:(a) 1 only (b) 1 and 2(c) 2 and 3 (d) 3 only

Ans. (d)Compiled By: S K Mondal Made Easy

IES – 2001Which of the following statements are the salientfeatures of hydrostatic extrusion?

1. It is suitable for soft and ductile material.2. It is suitable for high‐strength super‐alloys.3.The billet is inserted into the extrusion chamber and pressurepis applied by a ram to extrude the billet through the die.

4. The billet is inserted into the extrusion chamber where it issurrounded by a suitable liquid. The billet is extrudedthrough the die by applying pressure to the liquid.Select the correct answer using the codes given below:Codes:(a) 1 and 3 (b) 1 and 4(c) 2 and 3 (d) 2 and 4 Ans. (d)Compiled By: S K Mondal Made Easy

IES – 2006What does hydrostatic pressure in extrusion processimprove?(a) Ductility (b) Compressive strength(c) Brittleness (d) Tensile strength

Ans. (a)


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IES 2010Assertion (A): Pickling and washing of rolled rods is carried out before wire drawing.Reason (R): They lubricate the surface to reduce friction while drawing wires.(a) Both A and R are individually true and R is the(a) Both A and R are individually true and R is thecorrect explanation of A(b) Both A and R are individually true but R is NOT thecorrect explanation of A(c) A is true but R is false(d) A is false but R is true


IES – 2009Which one of the following stress is involved in thewire drawing process?(a) Compressive (b) Tensile(c) Shear (d) Hydrostatic stress

Ans. (b)


IES – 2000Match List I (Components of a table fan) with List II(Manufacturing processes) and select the correctanswer using the codes given below the Lists:

List I List IIA. Base with stand 1. Stamping andp g

pressingB. Blade 2. Wire drawingC. Armature coil wire 3. TurningD. Armature shaft 4. Casting [ Ans. (d)]Codes:A B C D A B C D(a) 4 3 2 1 (b) 2 1 4 3(c) 2 3 4 1 (d) 4 1 2 3Compiled By: S K Mondal Made Easy

IES – 1999Match List‐I with List‐II and select the correctanswer using the codes given below the Lists:

List‐I List‐IIA. Drawing 1. Soap solutionB Rolling 2 CamberB. Rolling 2. CamberC. Wire drawing 3. PilotsD. Sheet metal operations using 4. Crater

progressive dies 5. Ironing Ans. (d)Code:A B C D A B C D(a) 2 5 1 4 (b) 4 1 5 3(c) 5 2 3 4 (d) 5 2 1 3


IES – 1996Match List I with List II and select the correct answerList I (Metal/forming process) List II (Associated force)

A. Wire drawing 1. Shear forceB. Extrusion 2. Tensile forceC. Blanking 3. Compressive forceD. Bending 4. Spring back forceCodes:A B C D A B C D(a) 4 2 1 3 (b) 2 1 3 4(c) 2 3 1 4 (d) 4 3 2 1

Ans. (c)Compiled By: S K Mondal Made Easy

IES – 1996In wire drawing process, the bright shining surfaceon thewire is obtained if one(a) does not use a lubricant(b) uses solid powdery lubricant.(c) uses thick paste lubricant(d) uses thin film lubricant

Ans. (d)


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IES – 1994Match List I with List II and select the correct answer using the codes given below the Lists:List I (Metal farming process) List II (A similar process)

A. Blanking 1. Wire drawingB C i i Pi iB. Coining 2. PiercingC. Extrusion 3. EmbossingD. Cup drawing 4. Rolling

5. Bending [Ans. (d)]Codes:A B C D A B C D(a) 2 3 4 1 (b) 2 3 1 4(c) 3 2 1 5 (d) 2 3 1 5Compiled By: S K Mondal Made Easy

IES – 1993Match List I with List II and select the correctanswer using the codes given below the lists:List I (Mechanical property) List II (Related to)A. Malleability 1. Wire drawingB Hardness 2 Impact loadsB. Hardness 2. Impact loadsC. Resilience 3. Cold rollingD. Isotropy 4. Indentation

5. Direction [Ans. (b)]Codes:A B C D A B C D(a) 4 2 1 3 (b) 3 4 2 5(c) 5 4 2 3 (d) 3 2 1 5


IES – 2007Which metal forming process is used formanufacture of long steel wire?(a) Deep drawing (b) Forging(c) Drawing (d) Extrusion

Ans. (c)


IES – 2005Which of the following types of stresses is/areinvolved in thewire‐drawing operation?(a) Tensile only(b) Compressive only(c) A combination of tensile and compressive stresses(d) A combination of tensile, compressive and shearstresses

Ans. (a)


IES – 2000Which one of the following lubricants is mostsuitable for drawing mild steel wires?(a) Sodium stearate (b) Water(c) Lime‐water (d) Kerosene

Ans. (c)


IES – 1998Assertion (A): The first draw in deep drawing operationcan have up to 60% reduction, the second draw up to40% reduction and, the third draw of about 30% only.Reason (R): Due to strain hardening, the subsequentdraws in a deep drawing operation have reducedp g ppercentages.(a) Both A and R are individually true and R is the correctexplanation of A(b) Both A and R are individually true but R is not thecorrect explanation of A(c) A is true but R is false(d) A is false but R is true Ans. (a)


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IES – 1993Amoving mandrel is used in(a) Wire drawing(b) Tube drawing(c) Metal cutting(d) Forging

Ans. (b)


IES – 2002Match List I with List II and select the correctanswer:List I (Parts) List II (Manufacturing processes)

A. Seamless tubes 1. Roll formingB A d h b Sh iB. Accurate and smooth tubes 2. Shot peeningC. Surfaces having higher 3. Forging

hardness and fatigue strength4. Cold formingCodes: A B C A B C

(a) 1 4 2 (b) 2 3 1(c) 1 3 2 (d) 2 4 1

Ans. (a) Compiled By: S K Mondal Made Easy

IAS – 2004Assertion (A): Indirect extrusion operation can beperformed either by moving ram or by moving thecontainer.Reason (R): Advantage in indirect extrusion is lessquantity of scrap compared to direct extrusionquantity of scrap compared to direct extrusion.(a) Both A and R are individually true and R is thecorrect explanation of A(b) Both A and R are individually true but R is not thecorrect explanation of A(c) A is true but R is false(d) A is false but R is true Ans. (d)


IAS – 1995The following operations are performed whilepreparing the billets for extrusion process:1. Alkaline cleaning2. Phosphate coating3. Pickling4. Lubricating with reactive soap.The correct sequence of these operations is(a) 3, 1, 4, 2 (b) 1, 3, 2, 4(c) 1, 3. 4, 2 (d) 3, 1, 2, 4

Ans. (d)Compiled By: S K Mondal Made Easy

IAS – 2001Match List I (Products) with List II (Suitableprocesses) and select the correct answer using thecodes given below the Lists:

List I List IIA C ti d W ldiA. Connecting rods 1. WeldingB. Pressure vessels 2. ExtrusionC. Machine tool beds 3. ForgingD. Collapsible tubes 4. Casting Ans. (a)

Codes:A B C D A B C D(a) 3 1 4 2 (b) 4 1 3 2(c) 3 2 4 1 (d) 4 2 3 1Compiled By: S K Mondal Made Easy

IAS – 1997Extrusion force DOES NOTdepend upon the(a) Extrusion ratio(b) Type of extrusion process(c) Material of the die(d) Working temperature

Ans. (c)


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IAS – 2000Assertion (A): Brittle materials such as grey castiron cannot be extruded by hydrostatic extrusion.Reason(R): In hydrostatic extrusion, billet isuniformly compressed from all sides by the liquid.( ) B th A d R i di id ll t d R i th(a) Both A and R are individually true and R is thecorrect explanation of A(b) Both A and R are individually true but R is not thecorrect explanation of A(c) A is true but R is false(d) A is false but R is true Ans. (d)


IAS – 2002Assertion (A): In wire‐drawing process, the rodcross‐section is reduced gradually by drawing itseveral times in successively reduced diameter dies.Reason (R): Since each drawing reduces ductility ofthe wire, so after final drawing the wire isnormalized.(a) Both A and R are individually true and R is thecorrect explanation of A(b) Both A and R are individually true but R is not thecorrect explanation of A(c) A is true but R is false(d) A is false but R is true Ans. (b)


IES 2011Match List –I with List –II and select the correct answer using the code given below the lists :

List –I List –II

A. Connecting rods 1. Welding

CodesA B C D A B C D

(a) 2 1 4 3 (b) 3 1 4 2(c) 2 4 1 3 (d) 3 4 1 2

B. Pressure vessels 2. Extrusion

C. Machine tool beds 3. Forming

D. Collapsible tubes 4. Casting [Ans. (b)]

Compiled By: S K Mondal Made Easy Compiled By: S K Mondal Made Easy

Analysis of Extrusion

For Tube

dσ =B

10

0

h1 B 1B h

⎡ ⎤⎛ ⎞+ ⎢ ⎥σ − ⎜ ⎟⎢ ⎥⎝ ⎠⎣ ⎦

But B = 1 2

tan tanμ + μα − β

In the case of moving mandrel

B = 1 2

tan tanμ − μα − β

Maximum reduction possible

max

B1

0

h1 B 1 1B h

⎡ ⎤⎛ ⎞+ ⎢ ⎥− =⎜ ⎟⎢ ⎥⎝ ⎠⎣ ⎦

μ = μ = α = β =

⎛ ⎞= ≈⎜ ⎟

⎝ ⎠

01 2

1

0 max

if 0.05, 15 , 0hthen 0.4275 43%h

Extrusion ( ) 2B0 0

xof

1 B r1B r

⎡ ⎤σ + ⎛ ⎞⎢ ⎥σ = − ⎜ ⎟⎢ ⎥⎝ ⎠⎣ ⎦

Extrusion pressure (pt) = σ +fxo p

Extension load = 2t 0p r× π

Real condition ⎛ ⎞

= ⎜ ⎟⎝ ⎠

oo

f

AP k.A lnA

=where k extrusion constant

Reduction in Area (RA) =222 2

0 1 1 12

1 00

r r r D1 1r Dr

⎛ ⎞⎛ ⎞−= − = − ⎜ ⎟⎜ ⎟

⎝ ⎠ ⎝ ⎠

Analysis of wire/Rod Drawing

( ) ( ) ⎛ ⎞ ⎛ ⎞σ + σ π + − σ π + τ α π + α π =⎜ ⎟ ⎜ ⎟α α⎝ ⎠ ⎝ ⎠

2 2x x x x x

dx dxd r dr r cos 2 r P .sin 2 r 0cos cos

or σ + σ + τ + α =2x x x x2rdr d r 2r dx P .2rdx tan 0

or = α 2dx cot , and devide both by r drdr

or ( )σ τ+ σ + + α =x x

x xd 22 P cot 0dr r r

Vertical component of ≈x xP P and that of xτ can be neglected due to small half die angles. There fore only two principal stress xσ and xP Tresca’s condition

( )

σ + = σ

τ = μ = μ σ − σx x 0

x x 0 x

PP

Therefore ( )σσ μ+ + σ − σ α =0x

0 x2d 2 cot 0

dr r r

Taking μ αcot = B

( )xx 0

d 2 B 1 Bdr rσ

⎡ ⎤+ σ − + σ⎣ ⎦

Or ( )

x

x 0

d 2 drB 1 B r

σ=

σ − + σ

Integration both side ( )⎡ ⎤σ − + σ⎣ ⎦ =e x 0

e

log B 1 B2log rC

B

or ( ) ( )⎡ ⎤σ − + σ = =⎣ ⎦

2B

e x 0 elog B 1 B log rC where,C integretion constant

or ( ) ( )σ − + σ =2B

x 0B 1 B rC at 0 x br r ,= σ = σ

( ) ( )∴ σ − + σ =2B

b 0 0B 1 B r C

or ( )( )

12B

x 0

0

B 1 BC

rσ − + σ

=

or ( ) ( )⎛ ⎞⎡ ⎤∴ σ − + σ = σ − + σ⎜ ⎟ ⎣ ⎦

⎝ ⎠

2B

x 0 b 00

rB 1 B B 1 Br

or ( ) 2B 2B

0x b

0 0

1 B r r1B r r

⎡ ⎤σ + ⎛ ⎞ ⎛ ⎞⎢ ⎥σ = − + σ⎜ ⎟ ⎜ ⎟⎢ ⎥⎝ ⎠ ⎝ ⎠⎣ ⎦

Drawing stress, ( ) 2B 2B

0 1d b

0 0

1 B rr1 .B r r

⎡ ⎤σ + ⎛ ⎞ ⎛ ⎞σ = − + σ⎢ ⎥⎜ ⎟ ⎜ ⎟

⎢ ⎥⎝ ⎠ ⎝ ⎠⎣ ⎦

Now σ > σd 0 (in ideal case), therefore, maximum reduction can be found out,

Die Pressure

( ) B B

0 1 1d b

0 0

1 B h h1 .B h h

⎡ ⎤σ + ⎛ ⎞ ⎛ ⎞⎢ ⎥σ = − + σ⎜ ⎟ ⎜ ⎟⎢ ⎥⎝ ⎠ ⎝ ⎠⎣ ⎦

⎛ ⎞

= σ ⎜ ⎟⎝ ⎠

01

1

AP A lnA

Maximum Reduction or Draft per pass d

0

1σ=

σ

For zero back stress, the condition will be

( ) ( )B1 B1 1 RA 1

B+ ⎡ ⎤− − =⎣ ⎦

In wire and rod drawing, co-efficient of friction of the order 0.1 are usually obtained (by the use of proper lubrication) Now B = μ αcot

μ = α == × =

0.1 and 6B 0.1 9.515 0.9515

From hence, we will get the limited maximum reduction RA=50.5% Example: Calculate the drawing load required to obtain 30% reduction in area on a 12 mm diameter copper wire. The following data is given

0σ =240 N/mm2, 2α =120, μ=0.10 Calculate the power of the electric motor if the drawing speed is 2.3 m/s. Take efficient of motor is 98%. Solution: RA = 0.30 B = μ α = × σ =cot 0.1 cot 0.95

( ) 2B0 1

d0

1 B r1B r

⎡ ⎤σ + ⎛ ⎞⎢ ⎥σ = − ⎜ ⎟⎢ ⎥⎝ ⎠⎣ ⎦

( )

21

02

11

0

0.95 2d 0

rRA 1r

r 0.7 or r 0.7 6 5.02mmr

1.95 1 0.7 141.60N / mm0.95

⎛ ⎞= − ⎜ ⎟

⎝ ⎠

⎛ ⎞∴ = = × =⎜ ⎟⎝ ⎠

⎡ ⎤σ = σ × − =⎣ ⎦

Drawing load = 141.60 × π × 1r2 =11.21 kN

Power = 11.21 2.3 25.78 kW 26.31kW0.98

×= =

η

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Extrusion Fig Q a Analysis