Tugas Dhiyan Nur Ilham

8/18/2019 Tugas Dhiyan Nur Ilham

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International Journal of Machine Tools & Manufacture 44 (2004) 933–944

www.elsevier.comlocatei!mactool

" com#arison of ortho$onal cuttin$ %ata from e#eriments withthree %ifferent finite element mo%els

'alil il *. +n$in ,-l-c ". +rman Te//aa1e#artment of Mechanical +n$ineerin$ Mi%%le +ast Technical niversit "n/ara Tur/e

eceive% 5cto6er 20037 receive% in revise% form Januar 20047 acce#te% 28 Januar 2004

"6stract

The aim of this stu% is to com#are various simulation mo%els of ortho$onal cuttin$ #rocess with each other as well as with the results of

various e#eriments. ommercial im#licit finite element co%es M*.Marc 1eform21 an% the e#licit co%e Thir%wave "%vant+%$e have

6een use%. In simulations a ri$i% tool is a%vance% incrementall into the %eforma6le wor/#iece which is remeshe% whenever nee%e%. In

simulations with M*.Marc an% Thir%wave "%vant+%$e there is no se#aration criterion %efine% since chi# formation is assume% to 6e %ue

to #lastic flow therefore the chi# is forme% 6 continuousl remeshin$ the wor/#iece. 'owever in simulations with 1eform21 the

oc/roft–:atham %ama$e criterion is use% an% elements which ecee% the #re%efine% %ama$e value are erase% via remeshin$. esi%es

this %ifferent mo%elin$ of se#aration the three co%es also a##l %ifferent friction mo%els an% material %ata etra#olation schemes.

+stimate% cuttin$ an% thrust forces shear an$les chi# thic/nesses an% contact len$ths on the ra/e face 6 three co%es are com#are% withe#eriments #erforme% in this stu% an% with e#erimental results su##lie% in literature. In a%%ition effects of friction factor %ifferent

remeshin$ criteria an% threshol% tool #enetration value on the results are eamine%. "s a result it has 6een foun% that althou$h in%ivi%ual

#arameters ma match with e#erimental results all mo%els faile% to achieve a satisfactor correlation with all measure% #rocess

#arameters. It is su$$este% that this is %ue to the #oor mo%elin$ of se#aration.

; 2004 +lsevier :t%. "ll ri$hts reserve%.

,ewor%s< =inite element metho%7 5rtho$onal metal cuttin$7 emeshin$7 1ama$e7 =riction

8. Intro%uction

uttin$ is one of the most im#ortant an% common

manufacturin$ #rocesses in in%ustr. *im#lifie% analticalmetho%s have 6een %evelo#e% for eam#le 6 Merchant

>8? who intro%uce% the conce#t of shear an$le an% 6 :ee

an% *haffer >2? who #ro#ose% an analtical mo%el usin$

sli#@line fiel% theor. :ater more com#licate% mo%els >3–A?

have 6een %evelo#e% which also consi%er the effects of

friction wor/@har%enin$ an% tem#erature. These

successful mo%els $ave useful insi$ht into the mechanics of

cuttin$.

In recent ears finite element analsis has 6ecome the

main tool for simulatin$ metal cuttin$ #rocesses. +arl

analses were ma%e 6 sui an% *hira/ashi >?

orres#on%in$ author. Tel.< B90@382@280A237 fa< B90@38228082.

+@mail a%%ress< h6ilCmetu.e%u.tr ('. il).

0D90@9AAE @ see front matter ; 2004 +lsevier :t%. "ll ri$hts reserve%.

%oiF? who analGe% the stea%@state

ortho$onal cuttin$. hi# formation an% se#aration from

the wor/#iece was first attem#te% 6 *tren/ows/i an%

arroll >D?. hi# formation was achieve% 6 various


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'. il et al. International Journal of Machine Tools & Manufacture 44 (2004) 933–944 934

se#aration criteria li/e %istance tolerance criterion >9?

strain ener$ %ensit criterion >8088? an%

fracturemechanics 6ase% criterion >82?. To %eal with lar$e

element %istortion in metal cuttin$ simulation *hih an%

Han$ >83? an% *hih >848A? %evelo#e% a mesh reGonin$

techniue. eretti et al. >8? %evelo#e% a cuttin$ mo%el

6 %eletin$ elements havin$ reache% a critical value of

accumulate% %ama$e.

In almost all earl finite element mo%els %evelo#e%

non@commercial finite element co%es have 6een

em#loe%. 'owever a##lication of commercial finite

element co%es is #refera6le for in%ustrial utiliGation.

ecentl some commercial finite element co%es offer the

mo%elin$ of cuttin$. "s these co%es are 6ase% on

%ifferent al$orithms it is not /nown if an% 6 what

%e$ree results from each of them will %iffer. The aim of

this stu% is to evaluate these availa6le mo%els for

machinin$.

The commercial co%es M*.Marc 1eform21 an%

Thir%wave "%vant+%$e have 6een use% to create a

cou#le% thermo@mechanical finite element mo%el of

#lane@strain ortho$onal metal cuttin$ o#erations.

Material is mo%ele% as elastic–#lastic with flow stress

6ein$ %e#en%ent on strain strain rate an% tem#erature.

The friction 6etween the tool an% chi# is of shear t#e for

M*.Marc an% 1eform21 whereas it is of oulom6

t#e for Thir%wave "%vant+%$e. In simulation with

M*.Marc an% Thir%wave "%vant+%$e no %ama$e or

failure criteria are %efine% assumin$ the formation of

chi# %ue to #lastic flow. 'owever in simulations with

1eform21 the oc/roft–:atham %ama$e criterion has

6een use% althou$h the #lastic flow mo%el is also

availa6le in this co%e.

+#eriments have 6een #erforme% to verif the

simulation results. urel ortho$onal cuttin$ o#erations

can 6e %one on a sha#in$ machine with a sin$le #oint

cuttin$ tool or on a lathe 6 cuttin$ a hollow clin%er

with a lar$e %iameter an% small wall thic/ness from the

en%. In this stu% the latter metho% is use%. uttin$ an%

thrust forces are measure% 6 means of a %namometer.

In a%%ition contact len$th an% chi# thic/ness are

measure% an% shear #lane an$les are calculate% from the

measure% chi# thic/nesses.

2. =inite element mo%els

The finite element mo%el is com#ose% of a %eforma6le

wor/#iece an% a ri$i% tool. The tool #enetrates throu$h

the wor/#iece at a constant s#ee% an% constant fee% rate.

The mo%el assumes #lane@strain con%ition since

$enerall %e#th of cut is much $reater than the fee% rate.

The wor/#iece is %iscretiGe% 6 6ilinear four@no%e%

ua%rilateral elements in M*.Marc an% in 1eform21.

'owever Thir%wave "%vant+%$e uses si@no%e%

ua%ratic trian$ular elements 6 %efault. =i$. 8(a)(6)

shows the elements use%.

:eft an% 6ottom 6oun%ar no%es of the wor/#iece are

fie% in 6oth an% %irections 6 $luin$ them to a ri$i%

curve (=i$. 2). This coul% also 6e %one 6 %efinin$

=i$. 8. +lements use% in numerical mo%elin$. (a) M*.Marc an%

1eform21. (6) Thir%wave "%vant+%$e.

=i$. 2. Keneral $eometr of the finite

element mo%el with M*.Marc.

=i$. 3. Keneral $eometr of the finite

element mo%el with 1eform21.

6oun%ar con%itions7 however M*.Marc cannot han%le

this when $lo6al remeshin$ is ena6le%.

The finite element mo%el of 1eform21 is eactl the

same as M*.Marc ece#t for the satisfaction of the

con%ition on the left an% 6ottom 6oun%aries (=i$. 3) since

in 1eform21 the are %efine% as 6oun%ar con%itions an%not satisfie% 6 means of some $eometric entities.

5n the other han% "%vant+%$e is an automate% #ro$ram

an% it is enou$h to in#ut #rocess #arameters to ma/e a two@

%imensional simulation of ortho$onal cuttin$ o#eration.

The 6oun%ar con%itions are hi%%en to the user. =i$. 4

shows the mo%el of Thir%wave "%vant+%$e.

=riction 6etween the chi# an% tool interface is mo%ele%

as constant shear in M*.Marc an% 1eform21. 5n the

other han% Thir%wave "%vant+%$e uses the oulom6

friction mo%el.


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'. il et al. International Journal of Machine Tools & Manufacture 44 (2004) 933–944 93A

3. Lor/#iece an% tool material mo%elin$

The wor/#iece material use% for the #lane@strain

ortho$onal metal cuttin$ simulation is 8A steel. Its flow

curve is re#resente% 6 several ta6ulate% %ata (M*.Marc

%ata6ase) which %e#en%s on strain strain rate an%

tem#erature. These %ata re#resent the material flow curve

at three %ifferent strain rates (8. D an% 40 8s) an% 83

%ifferent tem#eratures (20 800 200 300v

400 A00 00 F00 D00 900 8000 8800 8200 ) while

strain chan$es 6etween 0 an% 8. " sam#le flow

=i$. 4. Thir%wave "%vant+%$e mo%el.

curve at 40 8s strain rate can 6e seen in =i$. A. =urther %etails are $iven in ef. >2?.

In the cuttin$ #rocess the %eformation at the cuttin$

Gone ta/es #lace at elevate% tem#eratures an% strain rates.

=or eam#le in the simulations #erforme% the

v tem#erature reaches

a6ove A00 an% the strain rates are in the or%er of 80 4 8s.

Therefore etra#olation is necessar. Kiven flow curves

are not etra#olate% with M*.Marc 6ut evaluate% at the

limit of the availa6le %ata ran$e. 1eform21 on the other

han% etra#olates usin$ the last two %ata #oints. In this

case when the strain rate ecee%s 40 8s some error is

intro%uce% %ue to im#ro#er flow stress evaluation. Thisetra#olation is a wea/ #oint of the finite element mo%els

use% in this stu%.

=i$. A. Lor/#iece flow curve for strain rate of 40 (8s).

=i$. . =low curves at %ifferent strain rates an% at a constant tem@v

#erature of A00 .

=i$. shows three flow curves at %ifferent strain rates

an% at a constant tem#erature which $ives an i%ea of

error intro%uce% %ue to im#ro#er flow stress evaluation at

elevate% strain rates.

"%vant+%$e finall uses an analtical formulation for

material mo%elin$. In a t#ical machinin$ event in the

#rimar an% secon%ar shear Gones ver hi$h strain rates

are achieve% while the remain%er of the wor/#iece

%eforms at mo%erate or low strain rates. In or%er toaccount for this Thir%wave "%vant+%$e incor#orates a

ste#wise variation of the rate sensitivit e#onent<

e #8=m8

r ¼ r f ðe #Þ 8 þ; if e # e #t ð8Þ # e 0

e #8=m2 e 8=m8 r ¼ r f ðe #Þ 8 þ #

8 þ #t ; if e # e #t e 0 e 0

ð2Þ


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93 '. il et al. International Journal of Machine Tools & Manufacture 44 (2004) 933–944

where r is the effective von Mises stress r f is the flow

stress e # is the accumulate% #lastic strain e #

0 is a

reference #lastic strain rate m8 an% m2 are low an% hi$h

strain@rate sensitivit e#onents res#ectivel an% e t is

the threshol% strain rate which se#arates the two re$imes.

In calculations a local Newton–a#hson iteration is use%

to com#ute e #

0 accor%in$ to the low@rate euation an%

switches to the hi$h rate euation if the result lies a6ove

e t. r f which is use% in +s. (8) an% (2) is $iven as<

e #8=n

r f ¼ r 0 wðTÞ 8 þ # ð3Þ e0

where T is the current tem#erature r 0 is the initial iel%

stress at the reference tem#erature T0 e #

0 is the reference

#lastic strain n is the har%enin$ e#onent an% w(T) is the

thermal softenin$ factor.

In the #resent stu% it is assume% that the tool is not

#lastifin$. 'ence it is consi%ere% as ri$i%. 'eat can 6etransferre% to the tool onl from the wor/#iece.

4. hi# formation

In recent ears formation of a continuous chi# is

assume% to 6e %ue to #lastic flow an% to simulate chi#

formation the wor/#iece is continuousl remeshe% e.$.

>8F–20?. The #resent stu% uses the same solution for

chi# formation in simulations with M*.Marc an%

Thir%wave "%vant+%$e.

In the mo%el analGe% with M*.Marc the wor/#ieceis remeshe% whenever a #re%efine% threshol% value of

tool #enetration occurs. Therefore a new 6oun%ar for

the wor/#iece at the tool–chi# interface is %etermine%

an% the wor/#iece is remeshe% accor%in$ to it formin$

the chi#. The %efault threshol% value of tool #enetration

is two times the contact tolerance value which is 6

%efault 0.0A times the minimum element e%$e len$th. In

a%%ition a #enetration chec/ can 6e selecte% to 6e

#erforme% at ever iteration or at the en% of increments.

"lthou$h a varin$ threshol% #enetration value

(%efault 0.0008 an% 0.000A mm was use% where the

avera$e element e%$e len$th is 0.08 mm) which is use%as a tri$$er for remeshin$ the wor/#iece %oes not

intro%uce a si$nificant %ifference the time of #enetration

chec/ has a stron$ effect on the results. uttin$ force

results o6taine% when the #enetration chec/ is %one at

ever iteration is almost half of those o6taine% when the

chec/ is %one at the en% of increments (=i$. F). In this

stu% the #enetration chec/ is %one at the en% of

increments.

The same simulations have also 6een %one with

1eform21. The 6asic %ifference 6etween the mo%els of

M*.Marc an% 1eform21 is the assum#tion ma%e for

the se#aration of material when the tool a%vances throu$h

the wor/#iece. In 1eform21 a %ama$e criterion is use% for

material se#aration. Therefore elements at the tool ti# are

erase% %urin$ remeshin$ when the have reache% a critical

%ama$e value. " normaliGe% oc/roft–:atham %ama$e

criterion has 6een use%. The critical %ama$e value has 6een

ta/en as 0.2 for 8A steel. It shoul% 6e re@em#hasiGe% that

1eform21 offers the o#tion of remeshin$ as well. ut in

this stu% the aim was also to investi$ate the se#aration

mo%el.

Thir%wave "%vant+%$e also uses remeshin$ to form the

chi#. It remeshes the wor/#iece #erio%icall to refine lar$e

elements remesh %istorte% elements an% coarsen small

elements. There is no user control for the remeshin$

#rocess.

A. 'eat transfer

The sources of heat $eneration are the #lastic wor/ in the

cuttin$ Gone an% friction at the tool–chi# interface. "t the

same time wor/#iece loses heat to the environment %ue to

convection an% to tool %ue to con%uction.

The rate of s#ecific volumetric flu %ue to #lastic wor/ is

$iven 6 the formula<

f ! L

¼ ð4Þ

where L is the rate of #lastic wor/ ! is the fraction of

#lastic wor/ converte% into heat which is ta/en as 0.9 f is

the mechanical euivalent of heat (ta/en as 8.0 6 %efault)

an% is the %ensit of wor/#iece material (F.DA $cm3).

The rate of heat $enerate% %ue to friction is $iven 6=i$. F. om#arison of cuttin$ force results o6taine% with %ifferent #enetration chec/ times.

the formula


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'. il et al. International Journal of Machine Tools & Manufacture 44 (2004) 933–944 93F

O

¼ =fr vr f ðAÞ

where =fr is the friction force vr is the relative sli%in$ velocit 6etween tool an% chi# an% f is the mechanical euivalent of

heat (f ¼ 8:0).

The $enerate% heat %ue to friction is $iven to each of the two contactin$ 6o%ies which are chi# an% tool in this case 6

eual #ro#ortions.

The wor/#iece loses heat to the environment %ue to convection accor%in$ to the formula<

h ¼ h ðTw T0Þ ðÞwhere h is the convection heat transfer coefficient of

v the wor/#iece (0.4 N(mm )) Tw is the wor/#iece surface tem#erature an% T0 is the am6ient

tem#erature

v (20 ).

. +#eriments

In this stu% e#eriments were %one 6 cuttin$ a hollow

clin%er from the en% on a lathe. In this e#eriment the

%iameter of the wor/#iece shoul% 6e relativel lar$er than

the %e#th of the cut (wall thic/ness of the tu6e) to satisf

ortho$onal cuttin$ con%ition. Lor/#iece material was 8Asteel with the inner an% outer %iameters 6ein$ A an% A3.8

mm res#ectivel. Therefore %e#th of the cut is 8.4A mm.

uttin$ tools were ma%e of hi$h s#ee% steel an% ha% ra/e

an$les of v v v

20 an% 2A an% A clearance an$le. uttin$ s#ee% was 82A

revmin.

" lathe tool %namometer was use% to measure cuttin$

an% thrust forces. ali6ration of the %evice was ma%e

6efore the cuttin$ e#eriments 6 a##lin$ /nown wei$hts

#ro$ressivel.

In a%%ition to the forces the thic/ness of cut chi#s an%

the contact len$th on the ra/e face were measure% 6

means of a tool ma/erPs microsco#e. *hear an$les were

calculate% from the measure% chi# thic/nesses.

F. esults

=inite element simulations were carrie% out for four cases

of e#eriments com#ose% of two %ifferent ra/e an$les an%

two %ifferent fee% rates with M*.Marc 1eform21 an%

Thir%wave "%vant+%$e se#aratel to eamine the effects of

%ifferent #arameters. Ta6le 8 shows the %ifferent

#arameters of e#eriments.In all simulations it is ma%e sure that stea%@state has

6een reache% an% some more %ata are collecte% after that

time. Therefore all the results #resente% in this wor/ were

$athere% un%er stea%@state con%itions.

=rom the simulations varia6les li/e stresses strains

strain rates an% tem#erature %istri6utions can 6e o6taine%.

'owever all these are ver %ifficult to measure

e#erimentall. 5n the other han% cuttin$ an% thrust

forces chi# thic/ness an% contact len$th can 6e measure%

relativel easil. "lso e#erimental results from the

literature are com#are% with the simulation results.

F.8. "naltical com#arison

"lthou$h the close% form analtical solutions of cuttin$

#rocesses are im#ossi6le there are analtical mo%els

%efinin$ allowa6le ran$es for the #ossi6le solutions of the

#rocess varia6les. In this stu% such three mo%els are use%

as a #reliminar vali%ation of the results o6taine% fromfinite element simulations.

*li#@line mo%els 6 :ee an% *haffer >2? ,u%o >28? an%

1ewhurst >22? $ive an allowa6le ran$e for the #ossi6le

solutions of the relation 6etween the shear #lane an$le

the ra/e an$le of the tool c an% the chi#–tool friction an$le

/. In this stu% %ia$rams have 6een %rawn with ( – c)

a$ainst / accor%in$ to 'illPs >23? overstressin$ criterion as

su$$este% 6 hil%s >24?. =i$. D(a)(6) shows allowa6le

ran$es for the ra/e an$les

v v of 20 an% 2A

res#ectivel.

=i$. D also shows the simulation results from M*.Marc."ll the results are 6etween the u##er an% lower 6oun%s

su$$este% 6 ,u%o an% 1ewhurst res#ectivel. The $ra#h

also shows that :ee an% *haffer mo%el which is relativel

sim#ler than the others $ives $oo% #re%ictions. +s#eciall

for the ra/ev

an$le of 20 simulate% results are almost coinci%ent with

the su$$este% solution of :ee an% *haffer.

F.2. hi# $eometr

Ta6le 2 shows the e#erimental results for the thic/nessof the cut chi#s an% contact len$ths 6etween the


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93D '. il et al. International Journal of Machine Tools & Manufacture 44 (2004) 933–944

Ta6le 8

Qarie% #arameters in the e#eriments

a/e an$les (%e$) =ee% rates (mmrev)

0.0A 0.8

20 +#. 8 +#. 2

2A +#. 3 +#. 4

=i$. D. "llowa6le sli#@line mo%el solutions 6 'illPs overstressin$

v v criterion. (a) =or ra/e an$le of 20 . (6) =or ra/e an$le of 2A .

Ta6le 2

+#erimental results of chi# $eometr #arameters

c (%e$) f (mm) tc (mm) (%e$) lc

20 0.0A 0.80 29.A4 0.DA

0.8 0.2F 28.F3 8.80

2A 0.0A 0.82 24.2 8.00

0.8 0.28 2D.24 0.90

chi# an% ra/e face of the tool where c is the ra/e an$le f

is the fee% rate (uncut chi# thic/ness) tc is the chi#

thic/ness is the shear an$le an% lc is the contact len$th.

*hear an$les are calculate% from the measure% chi#thic/nesses 6 usin$ +. (F). 'owever e#erimentall

measure% contact len$th results shoul% 6e consi%ere%

carefull since the measurements were ta/en on a

conventional lathe an% not on a uic/@sto# machine.

There ma 6e u# to A0R error in the measurements.

tanu ¼ r c cosc ðFÞ

8 r c sinc where r c is the

chi# thic/ness ratio.

*imulations of these e#eriments were carrie% out with

the three co%es at %ifferent friction factors an% friction

coefficients.

Ta6le 3 shows the results from M*.Marc. om#arin$

these results with the e#erimental results $iven in Ta6le

2 it can 6e conclu%e% that for m ¼ 0:F estimation of

chi# thic/ness is 6est. *hear an$le was foun% 6 two

was. =irstl since in the shear Gone strain rate is

si$nificantl lar$er than the remainin$ #arts of the

wor/#iece #lottin$ the euivalent strain@rate %istri6ution

su##lies the location of shear Gone an% hence shear an$le. *econ%l it can 6e calculate% from the estimate%

chi# thic/nesses 6 usin$ +. (F). esults show that

althou$h 6oth a##roaches are in $oo% a$reement the

strain@rate %istri6ution a##roach $ives a 6etter estimation

of the shear an$le since estimate% chi# thic/@

Ta6le 3


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hi# $eometr results o6taine% 6 M*.Marc

ness %eviates from the e#erimentall measure% values.

ontact len$ths on the other han% are ver #oorl

estimate%. ut here it shoul% 6e ta/en into account that the

measurement ma 6e overestimate% u# to A0R %ue to the

#rimitive measurement metho%.Ta6le 4 shows the results from 1eform21. hi#

thic/nesses are not ver well estimate% 6ut a$ain the results

are 6est when the friction factor is 0.F. *ince chi#

thic/nesses are #oorl estimate% the shear an$les which

are calculate% from them are also not in a$reement with

the e#eriments. 5n the other han% strainrate %istri6ution

$ives $oo% results onl for the case

v where ra/e an$le is 2A . ontact

len$ths are a$ain ver #oorl estimate%. "nother #oint

which is worth mentionin$ here is that the results from

1eform21 are not consistent 6etween each other an% the

are not sta6i@v liGe%. =or

eam#le for a ra/e an$le of 20 an% fee% rate of 0.0A

mmrev 6est result of shear an$le from strain@rate

%istri6ution is $ot when the friction factor isv

0.4. 'owever for a ra/e an$le of 2A an% fee% rate of 0.0A

mmrev the same shear an$le is 6est estimate% when the

friction factor is 0.F.

Ta6le A shows the results from Thir%wave "%vant+%$e.

The results of 6oth chi# thic/ness an% shear an$le are in

ver $oo% a$reement with the e#eriments. "s is

mentione% 6efore this #ro$ram uses the oulom6 frictionmo%el an% the chi# $eometr results are 6est estimate%

when the friction coefficient is ta/en as 0.A.

In view of the a6ove results it can 6e conclu%e% that the

three commercial co%e estimates the chi# thic/ness an%

shear an$le uite $oo% if an a##ro#riate friction factor or

coefficient is use%. 'owever the estimation of contact

len$th 6etween the chi# an% ra/e face of the tool is not in

a$reement with the e#eriments for all the co%es. 'owever

contact len$th results shoul% 6e consi%ere% carefull since

im#lemente% e#erimental measurement techniue ma

lea% to errors u# to A0R.

c (%e$) f (mm) tc (mm) m

¼ 0:2m ¼ 0:4 m ¼ 0:F

(strain rate) (%e$)

m ¼ 0:2 m ¼ 0:4 m ¼ 0:F

20 0.0A 0.0D 0.09 0.09 38.2 2D.08 2D.4A

0.8 0.8 0.8D 0.22 30.FF 30.9F 2A.8

2A 0.0A 0.0F 0.0D 0.88 34.D3 32.39 2F.F3

0.8 0.8A 0.8D 0.22 33.3 29.08 2F.39

20 0.0A

(chi# thic/ness) (%e$)

m ¼ 0:2 m ¼ 0:4 m ¼ 0:F

lc

m ¼ 0:2 m ¼ 0:4 m ¼ 0:F

3F.A 32. 32.4A 0.0 0.0D 0.82

0.8 3F.20 32.4A 2.D3 0.09 0.88 0.22

2A 0.0A 40.0 3.22 2D.3D 0.0A 0.0A 0.30

0.8 40.0F 34.32 2F.D 0.80 0.8A 0.22


8/14


=i$. 9(a)–(c) shows simulate% chi# $eometr from

M*.Marc 1eform21 an% Thir%wave "%vant+%$e

res#ectivel. "ll the #ictures were %rawn for the same tool

stro/e so that the are com#ara6le with each other.uttin$ con%itions are as the followin$< ra/e

v v

an$le is 20 clearance an$le is A fee% rate is 0.8 mm rev

%e#th of cut is 8.4A mm an% cuttin$ s#ee% is 82A revmin.

ontour lines in%icate the euivalent #lastic strain@rate

%istri6ution.

=i$. 80 on the other han% shows simulate% chi#

$eometries from three co%es when the ra/e an$le has

v 6een chan$e% to 2A while the other

cuttin$ con%itions were /e#t constant.

=i$s. 9 an% 80 show that M*.Marc an% Thir%wave

"%vant+%$e $ive almost the same chi# sha#es. 5n theother han% 1eform21 com#utes a more curle% chi#. =rom

contact len$th measurements it can 6e seen that 1eform21

simulates smaller values than the other two commercial

co%es which is the reason of more curle% chi#. 5n the

fi$ures euivalent #lastic strain@rate %istri6ution from

which shear an$le can 6e estimate% 6

Ta6le A

hi# $eometr results o6taine% 6 Thir%wave "%vant+%$e

measurin$ the an$le 6etween the horiGontal an% the line

connectin$ the two no%es with the hi$hest euivalent

#lastic strain@rate values on the free surface of thewor/#iece an% the tool ti# is #lotte% for com#arison

#ur#oses. Numerical values are alrea% $iven in Ta6les

3–A. This com#arison reveals that M*.Marc an%

Thir%wave "%vant+%$e a$ain su##l similar results

whereas 1eform21 simulates a lar$er shear an$le

althou$h the %ifference is small.

F.3. uttin$ forces

=i$. 88 shows the effect of friction on cuttin$ force

o6taine% 6 M*.Marc in com#arison with e#erimental

results. It can 6e state% that contrar to the chi#

$eometr varia6les cuttin$ forces are 6est estimate%

when the frictional shear factor is small. Lhen the

coefficient of shear friction is ta/en as 0.8 which is thesmallest value use% in the simulations cuttin$ forces are

estimate% with a maimum error of 4R.

Ta6le 4

hi# $eometr results o6taine% 6 1eform21

c (%e$) f (mm) tc (mm) (strain rate) (%e$)

m ¼ 0:2 m ¼ 0:4 m ¼ 0:F m ¼ 0:2 m ¼ 0:4 m ¼ 0:F

20 0.0A 0.0F 0.0D 0.09 32.F4 29.0 33.9

0.8 0.82 0.83 0.84 3D.F4 3F.48 33.9

2A 0.0A – 0.0F 0.0D – 29.93 2.AF

0.8 0.82 0.82 0.83 33.42 38.3 29.2D

20 0.0A


m ¼ 0:2 m ¼ 0:4 m ¼ 0:F

lc

m ¼ 0:2 m ¼ 0:4 m ¼ 0:F

44.4A 39.0 34.D 0.0 0.0F 0.0D

0.8 4D.2F 43.2D 42.99 0.88 0.83 0.84

2A 0.0A – 44.A 3F.A9 – 0.0 0.09

0.8 A8.2A 49.3D 4.2 0.82 0.88 0.82


9/14


=i$. 82 shows estimate% cuttin$ forces usin$ 1eform21.

=irst of all it shoul% 6e note% that the

v

=i$. 9. hi# $eometries for ra/e an$le of 20 < (a) M*.Marc (6)

1eform21 (c) Thir%wave "%vant+%$e (m ¼ 0:F for M*.Marc an%

1eform21 an% l¼ 0:A for Thir%wave "%vant+%$e).

v simulation

where ra/e an$le is 2A an% fee% rate is 0.0A mmrev

coul% not 6e com#lete% %ue to re#eate% software crash. It

can 6e seen that chan$in$ friction factor %oes not affect

the results as much as it %oes in the simulations of

M*.Marc. 'owever a$ain cuttin$ forces are 6est

estimate% when the friction factor is 0.8.

=i$. 83 shows cuttin$ force results from Thir%wave

"%vant+%$e. These force values are hi$her than the

v

=i$. 80. hi# $eometries for ra/e an$le of 2A < (a) M*.Marc (6)

1eform21 (c) Thir%wave "%vant+%$e (m ¼ 0:F for M*.Marc an%

1eform21 an% l¼ 0:A for Thir%wave "%vant+%$e).

values o6taine% 6 the two other co%es. The reason for this

is that Thir%wave "%vant+%$e ma/es use of the oulom6

friction law which su##lies re$ar%less of the ma$nitu%e of

interface #ressure a frictional stress that is #ro#ortional to

this #ressure. 'owever the #ressure values in these

eam#les are ver hi$h iel%in$ frictional shear stresses

which are lar$er than the shear

=i$. 88. Qerification of #re%icte% cuttin$ force results o6taine% 6

M*.Marc.


1eform21.

c (%e$) f (mm) tc (mm) (strain rate) (%e$)

l¼ 0:2 l¼ 0:4 l¼ 0:A l¼ 0:2 l¼ 0:4 l¼ 0:A

20 0.0A 0.09 0.803 0.88 2F.F3 2F.39 2F.FD

0.8 0.8D 0.288 0.23 38.04 2.39 2.8A2A 0.0A 0.09 0.80 0.80 32.28 38.8D 2.A0

0.8 0.8D 0.20 0.28 32.D 29.22 30.2A

20 0.0A


l¼ 0:2 l¼ 0:4 l¼ 0:A

lc

l¼ 0:2 l¼ 0:4 l¼ 0:A

32.92 2D.A9 2.D2 0.0F 0.0D 0.83

0.8 32.02 2F.9F 2A.D9 0.83 0.8F 0.24

2A 0.0A 34.F2 30.F8 29.A3 0.0 0.0 0.82

0.8 33.93 30.24 2D.3A 0.83 0.8A 0.8F


10/14




stren$th of the material. 'ence the su##lie% frictional

stress is not realistic for the friction coefficient selecte%. "

uantitative %iscussion of this #henomenon will 6e su##lie%

in *ection F.4.

=i$. 84 shows the com#arison of cuttin$ force results

from all the three commercial co%es as well as

e#erimental results. =or M*.Marc an% 1eform21 theresults corres#on%in$ to a friction factor of m ¼ 0:F have

6een selecte% 6ase% on the 6est correlation of the shear

an$le with e#eriments. In a similar wa for Thir%wave

"%vant+%$e l ¼ 0:A has 6een selecte%. 56viousl

1eform21 su##lies the 6est cuttin$ forces whereas

Thir%wave "%vant+%$e %eviates at most %ue to the friction

mo%el as e#ecte%.

=i$. 84. om#arison of cuttin$ force results from all co%es. m¼ 0:F for

M*.Marc an% 1eform21 an% l¼ 0:A for Thir%wave "%vant+%$e.

F.4. Thrust forces

=rom =i$. 8A it can 6e seen that for small friction

factors the tool a##ears to 6e %rawn into the wor/#iece.

The reason for this is that for small friction forces

(referrin$ to the s/etch on =i$. 8A) the vertical

com#onent of normal force (=n) ecee%s the normal

com#onent of friction force (=f ) hence the tool is

#ushe% into the wor/#iece. Lhen the friction factor is

ta/en as 0.F the results of thrust force switches to the

#ositive values. 'owever there are still si$nificant errors

in the results.

=i$. 8 shows the simulate% thrust force results

o6taine% usin$ 1eform21. It is seen that the same

ne$ative values also eists here. 'owever the thrust

forces never switch to the #ositive values even when the

friction factor is increase% to 0.F. This means that (= n) is

alwas com#ute% as lar$er than (=f ).

=i$. 8A. +ffect of friction factor on the thrust force results o6taine% 6

M*.Marc.

=i$. 8. +ffect of friction factor on the thrust force results o6taine% 6

1eform21.

Thrust force results from Thir%wave "%vant+%$e can

6e seen on =i$. 8F. These are the 6est estimate% results

for the thrust forces amon$ the three commercial co%es.

This co%e uses oulom6 friction mo%el in which

frictional stress on the ra/e face is calculate% from the

normal stress actin$ on the same surface an% not from theshear iel% stren$th of the material (initiall / 8FA

Ma). 'owever since the normal stress is ver hi$h

lar$er friction forces than the ones o6taine% usin$ other

two co%es result. This is reveale% in =i$. 8D where the

contact normal #ressure an% shear iel% stren$th of the

material alon$ the ra/e face of the tool %urin$ the cuttin$

o#eration are #lotte%. It can 6e seen that the resultin$

frictional stress is even hi$her than the shear iel%

stren$th which is #hsicall not #ossi6le. Therefore

(=f ) 6ecomes lar$er than (=n)

which means a #ositive


11/14


thrust force. In =i$. 8F it can also 6e seen that thrust

forces are 6est estimate% when the friction coefficient is

ta/en as 0.A. ut even than the results are not ver

accurate.

om#arison of all co%es accor%in$ to the results

o6taine% for thrust force are $iven in =i$. 89. "$ain

here the friction coefficients an% factors are selecte% to

have 6est a$reement with the e#erimental shear an$le

values. It is seen that 1eform21 is not a6le to #re%ict the

%irection of the thrust force. "lthou$h the %irection is

true for the other two co%es there are still si$nificant

errors.

=i$. 8F. +ffect of friction factor on the thrust force results o6taine% 6


=i$. 8D. om#arison of contact normal #ressure an% shear iel% stren$th of

the material alon$ contact len$th on the ra/e face.

F.A. esults 6 Movahhe% an% "lt-ntas

*ince the e#erimental techniue a##lie% in this stu%

was not accurate in %eterminin$ the contact len$ths it has

6een %eci%e% to #erform a com#arison with the stu% of

Movahhe% an% "lt-ntas >2A? in which a uic/@sto#

mechanism has 6een use% for measurin$ the contact len$th

accuratel. *ince the $eneral 6ehavior of the three co%es is

alrea% /nown from the com#arisons ma%e 6efore onl

M*.Marc has 6een use% for these com#arison.

Movahhe% an% "lt-ntas >2A? %i% ortho$onal metal

cuttin$ e#eriments with low car6on steel for the

verification of their finite element simulations o6taine% 6

a commercial co%e in which the have measure% cuttin$

force thrust force shear #lane an$le contact len$th an%

maimum tem#erature reache%.

The cuttin$ con%itions an% e#erimental results as well

as the simulation results of Movahhe% an% "lt-ntas can 6e

foun% in Ta6le where c is the ra/e an$le

=i$. 89. om#arison of thrust force results from all co%es. m¼ 0:F for

M*.Marc an% 1eform21 an% l¼ 0:A for Thir%wave "%vant@

+%$e.


12/14


Qc is the cuttin$ s#ee% f is the fee% rate %c is the %e#th of

cut =c is the cuttin$ force =t is the thrust force is the

shear an$le lc is the contact len$th an% Tma is the maimum

tem#erature.

Ta6le also shows the results of this stu% #re%icte% 6

M*.Marc where friction factor was ta/en as 0.8 (6ase%

on havin$ the same cuttin$ force with e#eriments of

Movahhe% an% "lt-ntas) an% material is 8A steel. It can

6e seen that other than the cuttin$ force #rocess #arameter

estimations are not in $oo% a$reement with e#erimental

results. Tem#erature #re%iction has an error a6out 9R

which can 6e acce#te% as a $oo% estimation.

5n the other han% with a friction factor of 0.F which is

#rove% to su##l 6etter results accor%in$ to the

com#arisons with e#eriments #erforme% in this stu%

thrust force #re%iction 6ecomes uite #recise while the

cuttin$ force is overestimate%. *hear an$le was simulate%

with an error of a6out AR. Tem#erature #re%iction 6ecomes

even 6etter %ue to hi$her heat $eneration at the chi#–tool

interface 6ecause of hi$her friction factor. The error is

a6out FR.

D. onclusions

This stu% reveals the effects of friction chi# formation

mo%el an% material %ata in the simulation of ortho$onal

cuttin$.

The friction #arameter affects the simulation results

%rasticall 6ut tunin$ this #arameter iel%s $oo% a$reement

onl for some varia6les in the ran$e. " smaller friction

#arameter lea%s to $oo% results for cuttin$ force whereas

other varia6les (such as thrust force an% shear an$le) are

com#ute% more accuratel with lar$er friction #arameters.

Therefore the accurac of a simulation must 6e assesse% 6 eaminin$ all #re%icta6le #rocess #arameters.

=urthermore tunin$ of friction #arameter shoul% 6e 6ase%

on the shear an$le varia6le since it %efines the mechanics

of the #rocess. =inall the #lain oulom6 friction mo%el is

not a##ro#riate for machinin$ #ur#oses since it su##lies

friction stresses which are lar$er than the shear iel%

stren$th of the material at the tool–chi# interface.

lain %ama$e mo%els for chi# se#aration are not

a##ro#riate for machinin$ #ur#oses. "lthou$h the

remeshin$ mo%el $ives 6etter results it is 6ase% on the

Ta6le

om#arison with the results of Movahhe% an% "lt-ntas >2A?

c (%e$) Qc (mmin) f (mmrev) %c (mm) =c (N) =t (N) (%e$) lc (mm)v

Tma ( )

+#eriment Movahhe%

"lt-ntas

0 8A0 0.8 8 8F4 D3 8D.D 0. A90

*imulation Movahhe%

"lt-ntas

0 8A0 0.8 8 20F 9 22 0.AA AF8

*imulation (m ¼ 0:8)

il ,-l-c Te//aa

0 8A0 0.8 8 8F4 28 22.8 0.8D A3A

*imulation (m ¼ 0:F)

il ,-l-c Te//aa

0 8A0 0.8 8 22A DA 8F.F 0.4A A4F


13/14

'. il et al. International Journal of Machine Tools & Manufacture 44 (2004) 933–944 94A

misconce#tion of the crac/ $eneration in the material at

the tool ti#. This can 6e e#laine% 6 =i$. 20. =irstl

#enetration of material into the tool occurs which tri$$ers

the remeshin$ ste#. " new mesh is %efine% with a new

surface which is 6i$$er than the former surface for a

constant volume. This is onl #ossi6le 6 intro%ucin$ a

crac/. This crac/ eists in%e#en%entl of the element siGe

use%. In a%%ition the %irection of this crac/ is not in the

%irection of shearin$. oth o6servations are the source

for the #oor a$reement with e#eriments in all

#arameters. " new soun% chi# se#aration mo%el is

necessar.

In a t#ical metal cuttin$ #rocess ver hi$h strain rates

(a6out 804 8s) are achieve%. 'owever the t#ical

availa6le material %ata are vali% u# to strain rates of 40

(8s). 1es#ite the fact that the etra#olation of flow

curves 6 three or%ers of ma$nitu%e of strain rate is

#erforme% 6 com#letel %ifferent #roce%ures in the

three analGe% co%es no si$nificant effect has 6een

o6serve% on the results. This ma 6e %ue to the

simultaneous effect of increase% flow stress %ue to hi$h

strain rates an% softenin$ %ue to the hi$h tem#eratures

reache% at the cuttin$ Gone. *till it shoul% 6e note% that

none of the well /nown shear an$le relationshi#s

=i$. 20. rac/ $eneration %urin$ a remeshin$ ste#.

are material %e#en%ent7 hence the real effect of material

6ehavior can onl 6e seen in the #arameters such as

tem#eratures forces an% contact len$th. 'owever to

asses these first of all a relia6le chi# se#aration mo%elmust 6e %evelo#e%.

"c/nowle%$ements

The authors want to than/ +rcen/ ",T"H from

=ISK+* om#an in Tur/e for ma/in$ the commercial

co%e Thir%wave "%vant+%$e availa6le an% 1oru/

M+15: from ritish olum6ia niversit in

ana%a for the e#erimental results su##lie%.

eferences

>8? M.+. Merchant Mechanics of the metal cuttin$ #rocess Journal of

"##lie% hsics 8 (894A) 2F–38D.

>2? +.'. :ee .L. *haffer The theor of #lasticit a##lie% to a #ro6lem of

machinin$ "*M+ Journal of "##lie% Mechanics F3 (89A8) 40A–483.

>3? .K. =enton .:.. 5le Mechanics of ortho$onal machinin$< allowin$

for the effects of strain@rate an% tem#erature on the tool–chi# friction

rocee%in$s of Institution of Mechanical +n$ineers 8D3 (899) 48F–43D.

>4? K. oothro% J.". aile +ffects of strain@rate an% tem#erature inortho$onal metal cuttin$ Journal of Mechanical +n$ineerin$ *cience D

(89) 24.

>A? Q. Korianis *. ,o6aashi *trains an% strain@rate %istri6utions in

ortho$onal metal cuttin$ "nnals of I 8A (89F) 42A.

>? +. sui T. *hira/ashi Mechanics of machinin$ from %escri#tive to

#re%ictive theor on the art of cuttin$ metals "*M+ +1 F (89D2) 83–

3A.

>F? ,. Iwata ,. 5sa/a%a H. Terasa/a rocess mo%elin$ of ortho$onal

cuttin$ 6 the ri$i%@#lastic finite element metho% Journal of +n$ineerin$

Materials an% Technolo$ 80 (89D4) 832–83D.

>D? J.*. *tren/ows/i J.T. arroll " finite element mo%el of ortho$onal metal

cuttin$ Journal of +n$ineerin$ for In%ustr 80F (89DA) 34F–3A4.

>9? ,. ,omvo#oulos *.". +r#en6ec/ =inite element mo%elin$ of ortho$onal

metal cuttin$ Journal of +n$ineerin$ for In%ustr 883 (8998) 2A3–2F.

>80? .. :in *.H. :in " cou#le% finite element mo%el of thermoelastic–

#lastic lar$e %eformation for ortho$onal cuttin$ Journal of +n$ineerin$

Material Technolo$ 884 (8992) 28D–22.

>88? M. sta =inite element analsis of ortho$onal metal cuttin$ o#erations

h.1. Thesis Mechanical +n$ineerin$ 1e#artment of Mi%%le +ast

Technical niversit "n/ara Tur/e 8999.

>82? J. 'ashemi ".". Tsen$ .. hou =inite element mo%elin$ of

continuous an% se$mental chi# formation in hi$h s#ee% ortho$onal

machinin$ Journal of Materials +n$ineerin$ an% erformance 3 ()

(8994) F82–F28.

>83? ".J. *hih '.T.H. Han$ +#erimental an% finite element #re%ictions of

resi%ual stresses %ue to ortho$onal metal cuttin$ International Journal of

Numerical Metho%s in +n$ineerin$ 3 (8993) 84DF–8A0F.

>84? ".J. *hih =inite element analsis of ortho$onal metal cuttin$ mechanics

International Journal of Machine Tools Manufacturin$ 3 (899) 2AA– 2F3.

>8A? ".J. *hih =inite element simulation of ortho$onal metal cuttin$ Journal

of +n$ineerin$ for In%ustr 88F (899A) D4–93.

>8? +. eretti . =all6ohmer L.T. Lu T. "ltan "##lication of 21 =+M to

chi# formation in ortho$onal cuttin$ Journal of Materials rocessin$

Technolo$ A9 (899) 89–8D0.

>8F? '. oroucha/i ". herouat . :au$ ,. *aanouni "%a#tive remeshin$

for %uctile fracture #re%iction om#tes en%us Mecaniue 330 (2002)

F09–F8.

>8D? K.*. *e/hon J.:. henot Numerical simulation of continuous chi#

formation %urin$ non@stea% ortho$onal cuttin$ +n$ineerin$

om#utations 80 (8993) 38–4D.

>89? M. a/er J. osler . *iemers " finite element mo%el of hi$h s#ee%

metal cuttin$ with a%ia6atic shearin$ om#uters an% *tructures D0 (2002)

49A–A83.

>20? =. ,loc/e *. 'o##e *imulation of the metal cuttin$ #rocessU relia6ilit

an% o#timiGation International Journal of ro%uction +n$ineerin$ an%

om#uters 4 (2003) 43–A2.

>28? '. ,u%o *ome new sli#@line solutions for two %imensional stea% state

machinin$ International Journal of Mechanical *ciences F (89A) 43–AA.

>22? . 1ewhurst 5n the non@uniueness of the machinin$ #rocess rocee%in$

of oal *ociet "30 (89FD) ADF–80.

>23? . 'ill The mechanics of machinin$< a new a##roach Journal of

Mechanics an% hsics of *oli%s 3 (89A4) 4F–A3.

>24? T.'.. hil%s Numerical e#eriments on material #ro#erties an%

machinin$ #arameters influencin$ normal contact stress 6etween chi# an%


14/14


tool niversit of :ee%s *chool of Mechanical +n$ineerin$ I Linter

Meetin$ =e6ruar 2003.

>2A? M.. Movahhe% ":+ *imulation of chi# formation in ortho$onal metal

cuttin$ #rocess h.1. Thesis *u#ervise% 6 H. "lt-ntas 1e#artment of

Mechanical +n$ineerin$ The niversit of ritish olum6ia Qancouver

ana%a 2000.

>2? '. il *imulation of ortho$onal metal cuttin$ 6 finite element analsis

M*c. Thesis Mechanical +n$ineerin$ 1e#artment of Mi%%le +ast

Technical niversit "n/ara Tur/e 2003.

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