IManE_Trifanescu_2014

8/10/2019 IManE_Trifanescu_2014

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Study on Processing of Titanium Aluminide Alloy using ElectricalDischarge Machining

TRIFANESCU Mihai1,a, BANU Alexandra1,b, AURELIAN Vişan1,c, IONESCUNicolae1,d, ARASC!IV Alexandr"1,e and SAVIN Alexandr"1,#

1, OLITE!NICA Uni$er%i&' o# B"chare%&(Ro)ania, *e+ar&)en& o# Man"#ac&"rin Technolo'a&ri#'-&l.'ahoo/co), a-ban"-0.'ahoo/co), ca"relian$i%an02.'ahoo/co),

dione%c"-"+b.'ahoo/co), ealex/+ara%chi$34.'ahoo/co), # %a$inalexandr".'ahoo/co)/

Keywords: Electrical Discharge Machining, Titanium Aluminide Alloy

Abstract. Currently there is a continuous extension of application areas of titanium aluminides buttheir processing encounter a number of difficulties such as the precision of machining and modifyingthe properties of the surface layer. In the literature [2] different authors address the processing of these materials by conventional methods. In this context, this paper aims at finding the optimal

regimes where the electrical discharge machining (!"# of titanium aluminides $i%&'l%)*+%-and analysis of the influence of process parameters on cutting through wire !" technologicalcharacteristics. a wire !" s%a ob/inut o productivitate relativ bun0 1i o rugoitate foarte bun0 asuprafe/elor prelucrate. 3n schimb, la die sin4ing !" datorit0 productivit0/ilor foarte mici au fostrealiate mai multe determin0ri experimentale pe trei ma1ini 5 6odic4, 7* 1i 8. 9e baadatelor experimentale s%a stabilit c0 cea mai bun0 productivitate se ob/ine la prelucrarea cu

polaritatea invers0

Introduction

Cercet0rile din preenta lucrare sunt o parte a unei lucr0ri de cercetare mai ample care :1i propune

stabilirea unor tehnologii optime de prelucrare a aluminurilor de titan prin diferite procedee, :nvederea utili0rii acestor materiale :n domeniul aeronautic. !e1i au o densitate mic0 aluminurile detitan au o reisten/0 mare 1i sunt foarte greu prelucrabile.

ccording to specialised literature the most important machining procedure of the ;amma$itanium luminide are brasive <ater=et "achining [>, ?], lectrochemical "achining [2], "illing[] and @igh 6peed "illing [A], lectrical !ischarge "achining [&], <ire lectrical !ischarge"achining [)] and ;rinding [B].

$he studies regarding brasive <ater=et "achining ("# [>] demonstrated that this procedurecan be accomplished to '.'2) mm accuracy, is relatively inexpensive and highly productive and can

be used in aero%engine components machining [?]. In lectrochemical "achining (C"# [2] stabledissolution has been shown to be limited by surface passivation, in case of the chloride system, and

cho4ing in case of the perchlorate system. "illing operations are very difficult to apply for titaniumaluminides machining because of rapid wear of the tool. nd%milling tools made of integral hardmetal can be use, applying different feeds and cutting speeds []. In high speed machining the toollife can be increase simply by controlling or avoiding the failure mechanism [A] and this procedure

become feasible in case of high%speed rough milling of gamma titanium aluminides at speeds of >)2%22D mEmin using directed through%spindle coolant with uncoated carbide and 9C! tooling. 6ome

papers [B] reports that in experimental investigation of grinding has been induced subsurface damagein gamma titanium aluminide. $he severity and depth of the subsurface damage one increased withan increase in the abrasive grit sie and the depth of cut. "icro%!" in dry conditions can be usedfor micro machining of F%$itanium luminide [&]. $he high heat and fire resistance property of thismaterials prevents arcing issues during shot circuiting with low energy discharge and no deformation

appear after machining. It was observed [&] that for given micro%!" process parameters the crater depth formation by a single discharge in the absence of dielectric liGuid (dry%micro%!"# isrelatively small, compared to machining in presence of dielectric oil and, in the same time theelectrostatic force induced between the tool and wor4 piece is considerably small in dry machining.In wire%electrical%discharge%machining operations the most important parameters are pulse on time,



pulse off time, pea4 current, wire tension, dielectric flow rate and servo reference voltage [)]. In caseof optimum values of above mentioned machining parameter combinations this procedure offers avery good productivity and the Guality of machined surfaces is very good (can be obtain '.? Hm or lower values of Ra roughness parameter#.

vnd :n vedere cele mai sus men/ionate 1i num0rul relativ mic de lucr0ri existente consider0m c0

se impune sudiul :n continuare a prelucrarii prin electroeroiune a aluminurilor de titan.!etermin0rile din preenta lucrare vor sta la baa reali0rii unui program experimental complex careva fi realiat de c0tre autori.

Machining of titanium aluminides using wire electrical discharge machining (WEDM)

3n cadrul cercet0rilor realiate de c0tre autori a fost necesar0realiarea unor epruvete pentru incerc0ri la trac/iune. 9robelenecesare experimentelor au fost obtinute prin <!" a unor

piese cilindrice cu diametrul de >A mm din doua bare J)'x>>)mm respectiv J&'x>'' mm din $i%&'l%)*b%- (Kig.>#. 9robeleau fost taiate pe o masina 6odic4 )), grosimea firului utiliat

pe masina fiind de '.2) mm iar materialul firului este alam0CuLnB. 1a cum se poate observa din tabelul > care preintadatele pentru cele patru prelucr0ri din bara cu lungimea de >>)mm 1i, respectiv pentru cele trei prelucr0ri din bara cu lungime de>'' mm, s%a ob/inut o productivitate relativ bun0 1i o foarte bun0rugoitate.

9entru realiarea epruvetelor pentru :ncercarea la trac/iune s%a aplicat cu mare dificultatestrun=irea. 9entru filetarea capetelor nu a putut fi aplicat0 strun=irea deoarece spirele se reteau subac/iunea for/ei axiale. Incercarea de a realia acest filet prin electroeroiune cu mi1care orbital0 ae1uat, de asemenea, datorit0 productivit0/ii foarte sc0ute. 3n aceste condi/ii a fost adoptat0 o alt0modalitate de prindere.

$able >. 9arameter and technological characteristics in <!"

<or4%pieceE$ool%electrodematerials

lectricdischarge

pea4 current []

9olarity[%EM]

lectricdischarge

time ti

[Ns]

lectricdischarge

stop time t'

[Ns]

Cut length[mm]

"achiningtime[min]

9roductivityOw

[mm2Emin]

8oughness8a

[Nm]

CuLnBE $i%&'l%)*b%-

>' % >) >& ).2' D',) AB.A' '.A

CuLnBE $i%&'l%)*b%-

>' % >) >& )>.'2 )' >'2.'2 '.A

nalia microscopic0 a probelor a eviden/iat alterarea stratului superficial cu atomi de cupru.

Machining of titanium aluminides using die sinking EDM

3n vederea stabilirii unor regimuri optime de prelucrare au fost realiate determin0riexperimentale pe trei ma1ini din genera/ii diferite, respectiv 6odic4 O)), 7* C7"9C$1i 8 '>. Ca mediu de lucru s%a utiliat dielectricul "entro 2? (667 5 6tandard#.lectroii utilia/i pentru prelucrarea prin electroeroiune au sec/iunea transversal0 circular0,cu diametrul de B.B mm 1i sunt realia/i din cupru electrolitic (DDP cupru#. 9entru prindereaelectroilor au fost utiliate dispoitive de tip 87< care permit att prelucrarea prina1chiere a electrodului ct 1i centrarea :n raport cu axa ma1inii 1i poi/ionarea :n raport cu

piesa :n vederea prelucr0rii prin electroeroiune. 9iesele 1i electroii s%au cantarit cu balanta

analitica CCQ+, care are are o preciie de >'%)

g.Machining on Sodick AQ!. Qna dintre caracteristicile ma1inilor 6odic4 o constituie

faptul c0 lucrea0 cu un mare num0r de variabile ca m0rimi de intrare ale procesului. 3n

Kig. >. "achined parts using <!"



tabelul 2 se preint0 modul cum au fost stabilite valorile acestor parametri care pot fi :mp0r/i/i:n dou0 mari categoriiR lectrical conditions and "otion conditions.

In table 2 CSSS is the number of condition, 9l 5 polarity, 7* 5 electric discharge time,7KK 5 electric discharge stop time, I9 5 electric discharge pea4 current, 6- 5 servo voltage,6 5 servo speed, Q9 5 =ump 5 up time, !* 5 =ump%down machining time, 6 5 =ump speed,

*6 5 loran shape, 6$9 5 oran orbiting motion distance on one side, - 5 main supplyvoltage, @9 5 auxiliary power supply circuit control, pulse control, capacitor selection, 99 5 9IT!* pulse, shutoff circuit control, C 5 capacitor, - 5 arc detection level, 7C 5 on

pulse control, K 5 7KK pulse control, @6 servo, " 5 =ump mode, 6 5 loran speed anddirection and *" 5 oran mode.

$able 2. "achining parameters % 6odic4 O))lectrical conditions "otion conditions

CSSS 9

7* 7KK I9 6- 6 Q9 !* 6 *6 6$9 - @9 99 C - 7C K " 6 *"

C''> % '.>') '.>') '>2 'B' 2' ''? '>) 'A '''' '.''' 22 ''' >' ) ''>) '''' ''') '> '' '''

u fost realiate mai :nti prelucr0rile > 1i 2 din tabelul . !atorit0 uurii foarte mari aelectrodului 5 scula au fost abordate 1i alte regimuri cu intensitate mai mic0 (2& # cu ambele

polarit0/i. 3n aceste cauri s%a redus foarte mult uura electrodului dar s%a redus 1i productivitatea.6e poate observa diferen/a fosrte mare de productivitate fat0 de o/elul C>2', utiliat :n acest ca camaterial de referin/0.

$able . 9arameter and technological characteristics in !" on 6odic4 <or4%

pieceE$ool%electrodematerials

*o.of

exp.

lectricdischarge

pea4 current[]

9olarity[%EM]

lectricdischarge

time ti

[N6]

lectricdischarge

stop time t'

[N6]

"achiningtime[min]

lectrode wear [mm] @oledepth[mm]

ateralgap

[mm]

Cu E $i%&'l%)*b%-

> A % >2 >2 D.)) >.'AD 2.&? '.>)

Cu E $i%&'l%)*b%- 2 A % >2 >2 &> >.&) 2.> '.>)

Cu E $i%&'l%)*b%-

2& % &? >2 >) '.>> '.' '.>&

Cu E $i%&'l%)*b%-

& 2& M &? >2 ) '.' '.>&A '.>&

Cu E $i%&'l%)*b%-

) 2& M &? >2 >) '.')& '.&> '.>&

Cu E C>2' A 2& % &? >2 >) '.'>) '.>B '.>&Cu E C>2' B 2& M &? >2 ) '.'') 2.>D '.>&

Machining on "#A $om%act &. 9relucr0rile realiate pe aceast0 ma1ina au condus la productivit0/i extrem de mici, conform celor preentate :n tabelul &.

$able &. 9arameter and technological characteristics in !" on 7* Compact 2<or4%

pieceE$ool%electrodematerials

*o.of

exp.

lectricdischarge

pea4 current[]

9olarity[%EM]

lectricdischarge

time ti

[N6]

lectricdischarge

stop time t'

[N6]

"achining time[min]

lectrode wear [mm] @oledepth[mm]

ateral gap[mm]

Cu E $i%&'l%)*b%-

? 2& M &? >2 >) '.''' '.>A) '.>&

Cu E $i%&'l%)*b%-

D >A M &? >2 >)' '.'') '.>B '.>

Machining on E!E' &. 9relucr0rile realiate pe aceast0 ma1in0 au eviden/iat, de asemenea, productivit0/i extrem de mici, pentru ambele polarit0/i.

$able ). 9arameter and technological characteristics in !" on 8 '2<or4%

pieceE$ool% *o.

of lectric

discharge9olarity

[%EM]lectric

dischargelectric

discharge"achinin

g timelectrode wear [P] @ole

depthateral

gap



[)] 6ar4ar, 6, "itra 6., +hattacharyya +., Wire electrical discharge machining of gamma titaniumaluminide for optimum process criteria yield in single pass cutting operation, International ournalof "anufacturing $echnology and "anagement, 2''), vol. B, no. 2EE&, pp 2'B 5 22Y

[A] +arnett%8itcey !. !wayne, Highspeed milling of titanium and gammatitanium aluminide! "ne#perimental in$estigation, anuary >, 2''), $! Collection for "c"aster Qniversity . 9aper

I*8'&2>B.httpREEdigitalcommons.mcmaster.caEdissertationsEI*8'&2>BY

[B] *elson ., Zub @[email protected]., !anylu4a 6., ahanmirc C.% &ubsurface damage in grinding titaniumaluminide, "achining 6cience and $echnology, -olume >, Issue 2, >DDBY

[?] Tongl ".C., xintel !., Response of titanium aluminide alloy to abrasi$e 'ater(et cutting!)eometrical accuracy and surface integrity issues $ersus process parameters, ournal of ngineering "anufacturing, httpREEpib.sagepub.comEcontentE22E>E>D.abstract.[2] 9uertas, I., uis, C.. and lvare, ., 2''&, nalysis of the influence of !" parameters onsurface Guality, "88 and < of <C5Co. ournal of "aterial. 9rocessing $echnology, >)%>)&,

pp.>'2A5>'2.

[] $hermo%mechanical fatigue behaviour of the near%F%titanium aluminide alloy $*+%-)underuniaxial and multiaxial loading ".6c. 6tephen 9eter +roo4es, +"%!issertationsreihe%+and &,+erlin 2''D.

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