imp metal casting

7/25/2019 IMP Metal Casting

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METALFABRICATION


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METAL FABRICATION

How do we fabricate metals? Blacksmith hammer !for"ed#

Cast molte$ metal i$to mold

Formi$" O%eratio$s

Ro&"h stock formed to '$al sha%e

Hot worki$" (s) Cold worki$" Deformation temperature

high enough for

recrystallization

Large deformations

Deformation below

recrystallization

temperature

Strain hardening occurs

Small deformations


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METAL FABRICATION METHO*+ !I#

FORMI!

roll

Ao

Adroll

Rolling "#ot or $old Roll

"I&beams' rails' sheet ( pla

Ao Ad

force

die

blan)

force

Forging "#ammering* Stamping%

"wrenches' cran)shafts%

often at

ele+, T

-dapted fro

Fig, ..,/'

Callister &

Rethwisch 8

ram billet

container

container

forcedie holder

die

Ao

e0trusion

10trusion

"rods' tubing%

ductile metals' e,g, $u' -l "hot%

tensileforce

Ao

Addie

die

Drawing

"rods' wire' tubing%

die must be well lubricated ( clean

$-S2I! MIS$1LL-1O3S


4/17

Forgingis mecha$icall,worki$" or deformi$" a

si$"le %iece of a $ormall,hot metal- this ma, beaccom%lished b, thea%%licatio$ of s&ccessi(eblows or b, co$ti$&o&s

s.&ee/i$")

For"i$"s are classi'eeither closed or o%e$

For closed die0 a fobro&"ht to bear o$more die hal(es hthe '$ished sha%ethat the metal is d

i$ the ca(it, betwthem

For o%e$ die0 two ha(i$" sim%le "eosha%es !e)")0 %ara

semicirc&lar# are


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Rolli$"0 the most widel, &seddeformatio$ %rocess0 co$sists of

%assi$" a %iece of metal betwee$two rolls- a red&ctio$ i$ thick$essres&lts from com%ressi(e stressese2erted b, the rolls) Cold rolli$" ma,be &sed i$ the %rod&ctio$ of sheet0

stri%0 a$d foil with hi"h .&alit,s&rface '$ish


7/17

For e2tr&sio$0 a bar of metal isforced thro&"h a die ori'ce b, acom%ressi(e force that is a%%lied to

a ram- the e2tr&ded %iece thatemer"es has the desired sha%e a$da red&ced crosssectio$al area)E2tr&sio$ %rod&cts i$cl&de rods a$dt&bi$" that ha(e rather com%licated

crosssectio$al "eometries- seamlesst&bi$" ma, also be e2tr&ded)


8/17

*rawi$" is the %&lli$" of a metal%iece thro&"h a die ha(i$" a ta%ered

bore b, mea$s of a te$sile force thatis a%%lied o$ the e2it side) Ared&ctio$ i$ cross sectio$ res&lts0with a corres%o$di$" i$crease i$le$"th) The total drawi$" o%eratio$

ma, co$sist of a $&mber of dies i$ aseries se.&e$ce) Rod0 wire0 a$dt&bi$" %rod&cts are commo$l,fabricated i$ this wa,)


9/17

METAL FABRICATION METHO*+ !II#

FORMI! $-S2I!

$asting& mold is filled with molten metal

metal melted in furnace' perhaps alloyingelements added' then castin a mold

common and ine0pensi+e

gi+es good production of shapes

wea)er products' internal defects

good option for brittle materials

MIS$1LL-1O3S


10/17

METAL FABRICATION METHO*+ !III#

Sand $asting "large parts' e,g,' auto engine bloc)s%

4hat material will withstand T5.677and is ine0pensi+e and easy to mold

-nswer: sand;;;

2o create mold' pac) sand around fo"pattern% of desired shape

Sand Sand

molten metal

FORMI! $-S2I! MIS$1LL-1O3S


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METAL FABRICATION METHO*+ !I3#

Stage I< Mold formed by pouring

plaster of paris around wa0 pattern,

=laster allowed to harden, Stage II< 4a0 is melted and thenpoured from mold


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14/17

METAL FABRICATION METHO*+ !3#

$ontinuous $asting

&& simple shapes "e,g,' rectangular slabs'

cylinders%

molten

solidified

FORMI! $-S2I! MIS$1LL-1O3S

Die $asting

&& high +olume

&& for alloys ha+ing low melting temperatures


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METAL FABRICATIONMETHO*+ !3I#

MIS$1LL-1O3S$-S2I!

=owder Metallurgy "metals w?low ductilities%

pressure

heat

point contactat low T

densificationby diffusion athigher T

areacontact

densify

4elding "when fabrication of one large

part is impractical%

#eat&affected zone:

"region in which the microstructure has been

changed%,

-dapted f

..,@' Call

Rethwisch

"Fig, ..,@

Castings

Handbook

4alton an

Opar "1d,

piece . piece B

fused base meta

filler metal "melted%base metal "melted

unaffectedunaffected

heat&affected z

FORMI!

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