1 - Metal Cutting Theory

8/9/2019 1 - Metal Cutting Theory

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SUBJECT TITLE:

MODERN MANUFACTURINGTECHNOLOGIES

CREDIT HOURS: 02

TEXT BOOK:

MANUFACTURING PROCESSESFOR ENGG MATERIALS BY SEROPE

KALPAKJIAN


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ASSESSMENT INFO

• One Hour Class Tests wtg: 20% x 02 = 40%

• Quizzes wtg: 3% x 5 = 15%

• Assignents wtg: 5% x 1 = 5%

• !inal wtg: 40 % x 1 = 40%

• "iniu Atten#an$e e&uire#: '5%

• Course "aterial: 1( )e$ture *li#es2( e+eren$e ,oo-s

3( .nternet


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"anu+a$turing /ro$ess

*tarting aterial /ro$esse# art

*$ra an# waste

" a $ 1 i n

e r 2

T o o l i n g / o w

e r

) a 3 o r

Manufacturing is the transformation of materials into items of greater value by means of one or more processing and/or assemblyoperations.


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at is "anu+a$turing

"anu+a$turing is te organize# a$ti6it #e6ote# to

te trans+oration o+ raw aterials into ar-etale

goo#s

/riar .n#ustr *e$on#ar .n#ustr

Agri$ulture7 !orestr7 "ining7

"ineral 8xtra$tion et$ "anu+a$turing .n#ustries

A anu+a$turing sste usuall elos a series o+ 6alue9a##ing

anu+a$turing ro$esses to $on6ert raw aterials into ore use+ul

+or an# e6entuall into +inise# ro#u$ts


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"anu+a$turing .n#ustries

• Two ,roa#er Categories w(r(t ro#u$t

Consuer goo#s

Caital goo#s

• "ore tan 450 #i++erent tes o+ in#ustries

a e $lassi+ie# wi$ a e groue#

in 20

*ee tale in next sli#e ((


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Indust! P"du#t C$t%&"!

Aerosa$e Caital

*iuil#ing Caital

"a$ine9Tool anu+a$turing Caital

Autooti6es Consuer ; Caital

8le$troni$s Consuer ; Caital

Couter "anu+a$turing Consuer ; Caital

Couter *o+tware Consuer ; Caital

"etal7 $oal7 oil Consuer ; Caital

Cei$al .n#ustr Consuer ; Caital

Textile .n#ustr Consuer

)eater .n#ustr Consuer

Cloting an# +ootwear Consuer

To a-ing Consuer

oo# an# tier ro#u$tion Consuer

/aer7 rinting ; ulising Consuer

,uil#ing "aterials Consuer ; Catial

!urniture .n#ustr Consuer

!oo# ro$essing Consuer


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"anu+a$turing /ro$esses

Classi+i$ation

• , ro$ess te$nolog

• , ro#u$t

• , ro#u$tion &uantit• , le6el o+ autoation

• An oter wa


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M$t%'$( R%)"*$( P"#%ss%s

+M$#,'n'n&-

"a$ining re+ers to $utting oerations tat are ase# on

te reo6al o+ aterial +ro an originall roug9sae#

wor-ie$e7 +or exale 6ia $asting or +orging troug

ower #ri6en a$ines(

"a$ining is te ro$ess o+ reo6ing unwante#

aterial +ro a wor-ie$e in te +or o+ $is( .+ te

wor-ie$e is a etal7 te ro$ess is o+ten $alle# etal

$utting or etal reo6al(

"a$ining is a anu+a$turing ro$ess in wi$ a sar

$utting tool is use# to $ut awa aterial to lea6e te

#esire# art sae(


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.ortan$e o+ "a$ining

• ariet o+ wor- aterials

•ariet o+ art saes an# geoetri$+eatures

• oo# sur+a$e +inises


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M$t%'$( R%)"*$( P"#%ss%s

+M$#,'n'n&-

A complex process and difficult to analyze. Why?


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M$t%'$( R%)"*$( P"#%ss%s

+M$#,'n'n&-

Tere are se6en asi$ $i +oration ro$esses:

./ Tun'n&

2( *awing3( >rin#ing

4( "illing

5( *aing

D( ,roa$ing

'(


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M$t%'$( R%)"*$( P"#%ss%s

+M$#,'n'n&-

Tun'n& is a machining process in which a single-point tool removes

material from the sur+a$e o+ a rotating $lin#ri$al wor-ie$eF te tool is

+e# linearl in a #ire$tion arallel to te axis o+ rotation7 as illustrate# in

!igure(

!or all etal $utting ro$esses7 it is ne$essar to #istinguis

etween speed 7 feed an# depth of cut


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M$t%'$( R%)"*$( P"#%ss%s

+M$#,'n'n&-

Cutting araeters

*ee# 6B is te riar $utting otion7 wi$ relates te 6elo$it o+ te

rotating wor-ie$e wit rese$t to te stationar $utting tool(

6 = G


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M$t%'$( R%)"*$( P"#%ss%s

+M$#,'n'n&-

Cutting *ee# in Turning

Cutting see# is te see# at te outsi#e e#ge o+ te art as it is rotating( Tis is

also -nown as sur+a$e see#(

Ta-e two weels7 one weel wi$ is tree +eet in #iaeter an# te oter weel

wi$ is one +oot in #iaeter7 roll ea$ weel one $olete turn !igureB(

,'#, ,%%( '(( t$*%( ;$t,%7 ,!7

Te larger weel will tra6el +arter e$ause it as a larger $ir$u+eren$e an# as

ore sur+a$e area( Cutting see#s wor- on te sae rin$ile


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M$t%'$( R%)"*$( P"#%ss%s

+M$#,'n'n&-


Te /" setting #een#s on te $utting see# an# te #iaeter o+ te art( Te

/" setting will $ange wit te #iaeter o+ te art( As te #iaeter o+ te art

gets saller7 te /" ust in$rease to aintain te re$oen#e# sur+a$e

see#(

Tin- o+ te art as a weel an# te $utting see# as a #istan$e( A larger weel

artB will nee# to turn +ewer re6olutions er inute to $o6er te sae #istan$e in

te sae aount o+ tie tan a saller weel artB( Tere+ore7 to aintain te

re$oen#e# $utting see#7 larger #iaeter arts ust e run at slower see#s

tan a saller #iaeter art(


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M$t%'$( R%)"*$( P"#%ss%s

+M$#,'n'n&-


Cutting see#s #een# riaril on te te o+ aterial ou are $utting

an# te -in# o+ $utting tool ou are using(

Te ar#ness o+ te wor- aterial as a great #eal to #o wit tere$oen#e# $utting see#(

Te ar#er te wor- aterial7 te slower te $utting see# an# 6i$e9

6ersa(

Te ar#er te $utting tool aterial7 te +aster te $utting see# an#6i$e96ersa(


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M$t%'$( R%)"*$( P"#%ss%s

+M$#,'n'n&-


E6$)(%

A $ut is to e a#e wit a ig9see# steel H**B tool on a 29in$ #iaeter

ie$e o+ 101I steel wit a rinnel ar#ness o+ 200( Cal$ulate te /" setting to

er+or tis $ut(

Cutting *ee# = 100 +B


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M$t%'$( R%)"*$( P"#%ss%s

+M$#,'n'n&-

Cutting araeters

Te #et o+ $ut #B is te #istan$e te tool is lunge# into te wor-ie$e(

Te turning oeration re#u$es te #iaeter o+ te wor- +ro its original

#iaeter $o to a final diameter $f # as determined !y the depth of cut d%

nits: in7 7

# =


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M$t%'$( R%)"*$( P"#%ss%s

+M$#,'n'n&-

Cutting araeters

!ee# +B is te #istan$e tool o6es towar#s wor-ie$e or te aount o+

aterial reo6e# er re6olution o+ te tool o6er te wor-ie$e(

Te +ee# in turning is generall exresse# in re6( Tis +ee# $an e$on6erte# to a linear tra6el rate in in te +orula

+ r = ?+

+ r = +ee# rate inB+ = +ee# re6B 9 set anuall

? = otational *in#le see#

re6inB


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M$t%'$( R%)"*$( P"#%ss%s

+M$#,'n'n&-

Cutting araeters

"a$ining tie $an e $al$ulate# using te +ollowing e&uation:

) = wor-art lengt B

T = "a$ining tie inB


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M$t%'$( R%)"*$( P"#%ss%s

+M$#,'n'n&-

"aterial eo6al ate "B: .t is te aount o+ aterial reo6e# te$utting tool in unit tie(

nits: in3in7 3in

"= 6B +B #B

Te units o+ L+L are expressed

simply as mm &in'# in effect

neglecting the rotationalcharacter of turning(

Cutting araeters


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M$t%'$( R%)"*$( P"#%ss%s

+M$#,'n'n&-

!ee# in "illingB

+ =+ tn?

"illing7 a ultile toot ro$ess as

two +ee#s: Te #istan$e tat tewor-ie$e +ee#s into ea$ toot as

it rotates7 $alle# te ;%%d %

t""t,7 + t7 tootB an# te rate at

wi$ te tale translates ast te

rotating tool7 $alle# te t$5(% ;%%d7

+ 7 in

ere n= no( o+ teet+ t


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Ot,"&"n$( Cutt'n& M"d%(

, #e+inition7 ortogonal $utting uses a we#ge9sae# tool in wi$ te

$utting e#ge is eren#i$ular to te #ire$tion o+ $utting see#(

As te tool is +or$e# into te aterial7 te $i is +ore# sear

#e+oration along a lane $alle# shear plane, wi$ is oriente# at s,%$

$n&(% M


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P')$! $nd S%#"nd$! S,%$ >"n%s


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Ot,"&"n$( Cutt'n& M"d%(Te tool in ortogonal $utting as onl two eleents o+ geoetr: 1B ra-e

angle an# 2B $learan$e angle( A $3% $n&(% 's t,% $n&(% 5%t%%n t,%(%$d'n& %d&% "; $ #utt'n& t""( $nd %%nd'#u($ t" t,% su;$#% 5%'n&

#ut/ Te ra-e angle LNL #eterines te #ire$tion tat te $i +lows as it is

+ore# +ro te wor-artF an# te $learan$e angle ME ro6i#es sall

$learan$e etween te tool +lan- an# te newl generate# wor- sur+a$e(

?

4ϕ


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F"#%s 'n M%t$( Cutt'n&

*e6eral +or$es $an e #e+ine# relati6e to te ortogonal $utting o#el(

!igure A: !or$es in etal $utting: aB +or$es a$ting on te $i in ortogonal

$utting7 an# B +or$es a$ting on te tool tat $an e )%$su%d(


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Te friction force ( is te +or$e resisting te +low o+ te $i along

te ra-e +a$e o+ te tool( Te normal force to friction ) iseren#i$ular to te +ri$tion +or$e( Tese two $oonents $an e

use# to #e+ine te $oe++i$ient o+ +ri$tion etween te tool an# te

$i:

Te +ri$tion +or$e an# its noral +or$e $an e a##e# 6e$toriall to

+or a resultant +or$e7 R.

R is oriente# at an angle P7$alle# te +ri$tion angle(


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.n a##ition to te tool +or$es a$ting on te $i7 tere are two +or$e

$oonents alie# te wor-ie$e on te $i: sear +or$e an#

noral +or$e to sear(

Te shear force ( s# is te +or$e tat $auses sear #e+oration to

o$$ur in te sear lane( Te normal force to shear ( n* is

eren#i$ular to te sear +or$e(

,ase# on te sear +or$e7 te sear stress tat a$ts along te sear

lane etween te wor- an# te $i is #e+ine# as:

were As =area o+ te sear lane( Tis sear lane area $an e

$al$ulate# as:

Te sear stress reresents te le6el o+ stress re&uire# to er+or

te a$ining oeration(


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!our +or$e $oonents (# )# (s# an# (n $annot e #ire$tl

easure# in a a$ining oeration7 e$ause te #ire$tions in wi$

te are alie# 6ar wit #i++erent tool geoetries an# $utting

$on#itions(

Howe6er7 it is ossile +or te $utting tool to e instruente# using a

+or$e easuring #e6i$e $alle# a #naoeter7 so tat two a##itional

+or$e $oonents a$ting against te tool $an e #ire$tl easure#i(e(

Te cutting force ( c # is in te #ire$tion o+ $utting7 te sae #ire$tion

as te $utting see# 67 an# te thrust force ( t is eren#i$ular to

te $utting +or$e an# is asso$iate# wit te $i ti$-ness e+ore te$ut t o.

Te rese$ti6e #ire$tions o+ tese +or$es are -nown7 so te +or$e

trans#u$ers in te #naoeter $an e aligne# a$$or#ingl


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8&uations $an e #eri6e# to relate te +our +or$e $oonents tat

$annot e easure# to te two +or$es tat $an e easure#(

sing te +or$e #iagra in !igure ,7 te +ollowing trigonoetri$

relationsis $an e #eri6e#:

.+ $utting +or$e an# trust +or$e are

-nown7 tese +our e&uations $an e

use# to $al$ulate estiates o+ sear

+or$e7 +ri$tion +or$e7 an# noral +or$e

to sear an# +ri$tion(


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Te "er$ant 8&uation

Assu)t'"n:

Te sear strengt o+ te wor- aterial is a $onstant7

una++e$te# strain rate7 teerature an# oter +a$tors(

Tere+ore te e&uation +or is an aroxiate relation

rater tan an a$$urate ateati$al e&uation(


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Te "er$ant 8&uation

Te sear lane angle $an e in$rease# :

1B.n$reasing te ra-e angle NB

2B


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Te "er$ant 8&uationA greater shear plane angle results in lower cuttingenergy , lower power requirements, and lower cuttingtemperature.

A i ti + T i


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Aroxiation o+ Turning

Ortogonal Cutting

!igure: Aroxiation o+ turning te ortogonal o#el: aB turningF an#

B te $orreson#ing ortogonal $utting(

A i ti + T i


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Aroxiation o+ Turning

Ortogonal Cutting

Con6ersion -e: turning oeration 6s( ortogonal $utting(

C tt' F ' T '


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Cutt'n& F"#%s 'n Tun'n&


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Types of Chips in Machining

• Chip formation affects the surface finish, cutting forces,

temperature, tool life and dimensional tolerance.

• Understanding the chip formation during the machining

process for the specific materials is useful to determine the

machining speeds, feed rates and depth of cuts for efficient

machining and increase tool life.


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During the machining process, four basic types of chips

are formed:

1. Discontinuous

2. Continuous

3. Continuous with uilt!up "dge

#. $errated chip formation


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Discontinuous chips: %hen relati&ely brittle materials 'e.g. cast iron( are

machined at low cutting speeds, the chips often form into separate

segments 'sometimes the segments are loosely attached(. )his tends to

impart an irregular te*ture to the machined surface. +igh tool!chip friction

and large depth of cut promote the formation of this chip type


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Continuous chip: %hen ductile wor materials are cut at high speeds and

relati&ely small feeds and depth of cut, long continuous chips are formed.

- good surface finish results when this type of chip is formed. - sharp

cutting edge of the tool and low tool chip friction encourage the formation

of continuous chips. ong, continuous chips can cause problems with

regard to chip disposal and /or tangling about the tool. )o sol&e these

problems, turning tools are often e0uipped with chip breaers.


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Continuous chip with built-up edge: %hen machining ductile materials at low tomedium cutting speeds, friction between tool and chip tends to cause portion of the

wor material to adhere to the rae face of the tool near the cutting edge. )his

formation is called a built up edge 'U"(. )he formation of U" is cyclical it forms

and grows, then becomes unstable and breas off. uch of the detached U" is

carried away with the chip, some times taing portions of the tool rae face with it,

which reduces the life of the cutting tool. ortions of the detached U" that are notcarried off with the chip become imbedded in the newly created wor surface, causing

the surface to become rough.


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Serrated or Shear localized chips: )hese chips are semi continuous inthe sense that they possess a saw!tooth appearance that is produced by a

cyclical chip formation of alternating high shear strain followed by low

shear strain. )his type of chip is formed during machining of metals

such as titanium alloys, nicel!base super!alloys, and austenitic stainless

steels at higher cutting speeds. +owe&er, the phenomenon is also found

with more common wor metals 'e.g. steels( when they are cut at high

speeds.


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Cutting Temperature

O+ te total energ $onsue# in a$ining7 nearl all o+ it aroxiatelKI%B is $on6erte# into eat( Tis eat $an $ause teeratures to e 6er

ig at te tool9$i inter+a$e9o6er D00 RC is not unusual( Te reaining

energ aout 2%B is retaine# as elasti$ energ in te $i

Cutting teeratures are iortant

e$ause ig teeratures 1B

re#u$e tool li+e 2B ro#u$e $is

tat ose sa+et azar#s to te

a$ine oerator an# 3B $an

$ause ina$$ura$ies in wor-art

#iensions #ue to teral

exansion o+ te wor- aterial(


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Cutting Temperature

Tere are 6arious was to easure re#i$t teerature:

1(!8 Analsis

2(Teral .aging Caera

3(/roeters

4(Tero$oules

an# an ore S


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Temperature at the Tool-Chip

InterfaceC""3=s ;")u($

4.3334.# ('U Vt

T C K ρ

∆ =

T=ean teerature rise at te tool $i inter+a$e7 C !BF =se$i+i$

energ in te oeration( U3 in9lin3B = $utting see# s insB

t=un#e+ore# $i ti$-ness inBF V$=6oluetri$ se$i+i$ eat o+ te

wor- aterial U39C in9lin39!BF W= teral #i++usi6it o+ te wor-

aterial7 2s in2sB

Hi h S d M hi i


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High Speed MachiningHig9see# a$ining H*"B eans using $utting see#s tat are

signi+i$antl iger tan tose use# in $on6entional a$iningoerations(

*oe exales o+ $utting see# 6alues +or $on6entional an# H*"

are resente# in Tale 1

Tale 1: Coarison o+ $utting see#s use# in $on6entional 6ersus ig9see#

a$ining +or sele$te# wor- aterials

i S i i


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High Speed Machining

Oter #e+initions o+ H*" a6e een #e6eloe# to #eal wit te

wi#e 6ariet o+ wor- aterials an# tool aterials use# in

a$ining(

Te $t'" "; ,"s%"% t" )$6')u) s'nd(% s%%d7 or

r ratio( Con6entional a$ine tools usuall a6e a igerr ratio tan a$ines e&uie# +or ig9see# a$ining(

Te #i6i#ing line etween $on6entional a$ining an# H*" is

aroun# 0(005 r(

H'&, s%%d )$#,'n'n& @ 0/00 ,1)

C"n*%nt'"n$( )$#,'n'n& 0/00 ,1)

Hi h S d M hi i


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Ad*$nt$&%s:

!aster ro#u$tion rates*orter lea# tiese#u$e# $osts greater nuer o+ ro#u$tsB

.ro6e# art &ualit

D's$d*$nt$&%s:

.nitial $aital $osteair ; aintenan$e issues*-ille# laour ; rograer

Hi h S d M hi i


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R%8u'%)%nts ;" HSM

1BHig9see# sin#les using se$ial earings #esigne# +or ig

r oeration

2BHig +ee# rate $aailit ti$all aroun# 50 in 2000

ininB

3BC?C otion $ontrols wit MMloo-9aea#EE +eatures tat allow te

$ontroller to see u$oing #ire$tional $anges an# to a-e

a#Xustents a$$or#ingl

4B,alan$e# $utting tools7 tool9ol#ers7 an# sin#les to iniize

6iration e++e$ts5BCoolant #eli6er sstes tat ro6i#e ressures an or#er o+

agnitu#e greater tan in $on6entional a$ining

DBCi $ontrol an# reo6al sstes to $oe wit te u$ larger

etal reo6al rates in H*"(

Hi h S d M hi i


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HSM A('#$t'"ns

A%"s$#% $nd A'#$;t 'ndust'%s in wi$ long air+rae stru$tural

$oonents are a$ine# +ro large aluinu lo$-s( "u$ etal

reo6al is re&uire#7 ostl illing( Te resulting ie$es are

$ara$terize# tin walls an# large sur+a$e9to96olue ratios(

Te a$ining o+ aluinu ultile oerations to ro#u$e a 6ariet o+

$oonents +or in#ustries su$ as $ut")"t'*% #")ut% $nd )%d'#$((

"ultile $utting oerations ean an tool $anges as well as ig

a$$elerations an# #e$elerations o+ te tooling(

Anoter ali$ation +or H*" is in te d'% $nd )"(d 'ndust!7 wi$

+ari$ates $olex geoetries +ro ar# aterials( .n tis $ase7 ig9

see# a$ining in6ol6es u$ etal reo6al to $reate te ol# or #ie

$a6it an# +inising oerations to a$ie6e +ine sur+a$e +inises(

Documents

1 - Metal Cutting Theory