Injection moulding proccss modelling anel optimization · Injection moulding proccss modelling anel...

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REVISTA MEXICANA DE FÍSICA -tS SU'LE.\IE:STO 1, 1-) Injection moulding proccss modelling anel optimization A. García-Rcjon. J.-E Hétll, D.M. Gao, ami L. Pecora Industrial IvlafC'rials /lIstitltfC', Nmiollal Research Cmmcil Callada 75 De MortaRllc, BOllcherl'illc, Québec J.JB 6 Y'¡ C(llIada Recibido el 2ú de febrero de ItJ9X:aceptado el 15 de Illar/o de It)t)X JUNIO 1999 The rapid gro\\'lh in Ihe use 01'advanccd matcrinls in a large numhl'r of highly demanding aulolllolive, ~porlS &.. leisure. elcclronics. tram- pmlation ami packaging applications has promotcd the dcvclopment uf ne\\' and more nllnple;<; Illaterial forming proccsses. The polymcr procc~siJlg lidd has gained imponance due to Ihe optimi/ation 01'nisling processes and lo the de"l'lupl1lerlt 01' ne\\' proccssing techniques ernploying novel cOllceplS. Injection moulding techniques such as gas-assislcd injection moulding have cxpamlt:L1Iheir range 01'application~. The complcxily of Ihese new moulding: lechniques amllhe need lo comply lo slricter tolerances ami demanding scrvice condilions calJs for;) J1l11chet1er underslanding of Ihe material hchaviour during lhe hasic stagcs 01'lhe process and ils relalion lo the propcrties and performance 01'lhe linal pan. Thesc characteristics are dirc(.'lly dependent upon fllould dcsigns and on lhe opcrating conditions during melting:. injecti(ln and cooting in lhe l11oulds. In Ihis papcr \"'Cwill uemonslrate ho\\' lhe nUl11cricalsirnulation (2.5 ami JD models) of the individual sleps 01' lhe injel"tioll alltl gas assislcd injection moulding processes can he used to optimize the process alltl prodll(,:t performance 01'industrinl pans. }\('.l"\l'Imls: Injl'clioll mOlllding; gas assisted injeclion ll1outding: compuler simlllalion; oplimizalion El r¡ípido allmenlo en el liSOde materiales avanzados en un gran mJmero dc automotores altamente dl'millldados. deportes y enseres. etec- trúnica. transporte y empaques. ha fomentado el desarrollo de Iluevos y m:ís complejos procesos de formación de maleriales. El rampo tk pn)(.'esillllicnto dc polímeros ha ganado importancia dehido a la oplimi/aci6n de !os pr(lcesos e;<;isll'ntes y al desarrollo de nuevas técnicas dc proceso l'mpkillldo cOI1l:eptos novedosos. Las técniGls dl' moldeo por inyecci6n como el Illoldeo por inyección asistido por gas, hnn C'xtl'nuidil su l'iunpo de aplicaciones. La complejidad tIe estas nuevas técnicas de moluco y la nl'(.'csidad dc cumplir con las lolerancias estrii..'las y conLli(:iones dl' servicio demandados, requieren de un mejor entendimiento del Ctllllpt1rtamil'nto de los malerinles durante las etapas h:ísicas JcJ proceso y su relación con las propicJades y funcionamiento de la parte final. Estas caral"terísticas dependen directamentl' lIl' los diseilos dcJ molde y de las condiciones de oper.¡ci6n duranll' la fundición. inyen:it'in y enfriamiento en los moldes. En este artículo dellloslraremos rómo la simulación numérica (moldes 2.5 y JD) de los intervalos individuales de los pnx"csos tIl' moldeo por inyección y de inyecci(lll asistida por gas pueden usarse para optimizar el proreso y funcionamiento del producto de partes induslriales. 1h'.\{Til'tOH'.\: ~loldl..'o por inyeccidn: moldeo por inyc(.'rión asi~tiuo: simulación por computadora: optimi/:ll'ión I'"es: 1'1.20.-n 1. Injection llIoulding process [1 J Injection lIlo1l1ding (Pig. 1) can he dividcd into four basi(.; SI¡¡g~S: plastifkalion; injc(.;tion; packing and (.;ooling and ~jec- lion. In Ihe plastilkation slagc the raw malerial in solid forlll is lransforllled inlo mollen material through lhe comhincd ¡¡((ioll 01" the friction providcd hy a rotating sue\\' ami lhe he al provided hy exlernal heating elcrnents. Thc screw re- lrarls durillg rotation in orde!" to accolllodale the Illollen lT1a- lcriallhal ;ll"l'Ulllulales in front of the screw. Onl"C a suflicient <llIllTlounl of material is availahlc. lhe scrcw 1110VCS forward, (.;tlusing lhe molten rnalerial to nll the cavity. Upolll'olllple- ¡ion 01' lil1ing, additional material is packcd inlo the cavily in onlcr lo compensale for lhe shrinkage occurring during lhe i..'ooling slagc. Once solitlilicd. the J110ulded artide is ejected and the scqllence 01' evenls is rcpcalcJ in a cyclic manllcr. Due lo lhe pOOl' thermal (';(lIldllctivity of polymcric material s, lhe cooling lime gencrally constitules the dominanl portion (JI' ¡he 1l1Oulding l'ycle. Gas assisled inje<..'lion moulding (Fig. 2) has rapiJly gained a(,l'eplanee dlle to its \'crsatilily in lhe prodllclioll nI" rH,URE l. Injcclioll Illoulding rroccss. complex hollo\\' parts. Duc to lhe gas/polymcr interactiotl during the gas interaclion during the gas injection phase, the pressure reqllircl11cnts as wcll as lhe shrinkage/warpage of the part can he grcatly reduecd. The typical gas-assisted injection moulding process comprises lhe fol1O\\'ing stcps: a) polymcr f1l1ing; h) gas injcclion; and e) packing slagc. During polymer lilling the cavily is partly fillcd (up lo 80%). Shortly after the cnd 01' the polymcr injcction, the gas is in- jected to hollo\\'-ollt lhe gas channels until the cavity is com- pletely t1l1ed. The rclativc Illclt/gas llowrate \ViII determine
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Transcript of Injection moulding proccss modelling anel optimization · Injection moulding proccss modelling anel...

  • REVISTA MEXICANA DE FSICA -tS SU'LE.\IE:STO 1, 1-)

    Injection moulding proccss modelling anel optimization

    A. Garca-Rcjon. J.-E Htll, D.M. Gao, ami L. PecoraIndustrial IvlafC'rials /lIstitltfC', Nmiollal Research Cmmcil Callada

    75 De MortaRllc, BOllcherl'illc, Qubec J.JB 6 Y' C(llIada

    Recibido el 2 de febrero de ItJ9X:aceptado el 15 de Illar/o de It)t)X

    JUNIO 1999

    The rapid gro\\'lh in Ihe use 01' advanccd matcrinls in a large numhl'r of highly demanding aulolllolive, ~porlS &.. leisure. elcclronics. tram-pmlation ami packaging applications has promotcd the dcvclopment uf ne\\' and more nllnple;

  • 2 A GARCA-REJON. J.-F. IITU. IlM GAO. ANO L I'ECORA

    Fr(iU\{E") Gas AssislcLl injecton llloulJing.

    Frozsn layerGas pene!ra1iOnregion PoIymeifIIedrBQIOl'1 IE~ f't9on

    Calculaban cIomain

    2.1. :"'umcri

  • INJECTION MOULDING PROCESSMODELI.I:'\G ANI) (Wn~lIZAT/().\I

    r:1(iURE 4. PolYl1lcr. Front lor.:alion al Ihe eno of potimcr injeclion.

    l.~,= 1 (.I(,lllE'll! l'Olllllll'tl'iy fil1cd wilil polYlllcr.

    0< F, < () ('J

  • A, GARCA-REJON. J.-F IITLJ. J),~1 GAO, ANI> L I'En mA

    .('" .-, (1 = I,,,,[T - T",I Oll r('oolillK lill"s'~,.(111 = 1,,,[1'- 1'0] on ramhi"lllo ( 1 1 )

    ,...'~"...-~.....04_'"

    FI(illl

  • I~JECTION MOULDlNG PROCESSMODELLING AND OPTI~lIZATION 5

    (b)

    (d)

    (f)(e)

    (a)

    (e)

    FIGURE 9. Flow front aJvanccmcnl at Jiffercnl tilling stages.(a) 0025 scc, (b) 0.05 sce, (e) 0.10 see. (d) 0.30 scc, (e) 0.40 sce,(f) 0.50 see.

    4. Conclusions

    FIGURE 8. SaliJ moJel of the C,lr Joor hanJle anJ moulJ a~scmbly,

    T\vo lnile elclllent mollels (2,5 and 3D) have heen tlevelopcd((l simulate thc lilling slagc for gas assistcd injeclioll Illould-ing and Ihe injeclion mllUlding of a thick-walletl parl. The ha-sic phenomcna 01"!low front advanccmcnt antl prcssure andlemperaturc tlistrihulions can he accuralely prediclcd hy themodcls.

    Figure 9 shows Ihe advancclIlcnt 01"Ihe !low fronl al dif-ferent slages 01"lhe filling rhasc. Jt can he scen that Ihc ma-Icrial cn(ers lhc cavity, hits thc oppositc waIl and thcn ad-\'anccs towards Ihe mctal inscrt locatcd at both ends of theparto The malerial 110ws around Ihc inserl and \vill form awcldlinc \vhich might he a possihlc weak spot in the finalparl.

    1. D, Rosalo anJ D. Rosato. "jection ",oldi,,~ IIwulhook. (VanNostranJ. Ncw York 1989).

    2. C.A. lIicbcr. 1. NOII-New(ollia" Fluid Mec!ulIlics 7 (1980) 1.3 p, KcnncJy. Flo\\' Allalysis oIllIj('clion Motllds. (Hanscr. Ncw

    York. 1995) .

    .1. c.w. Hirtand B.D. Nichols.J. Comp. Physio39(1981)201,:i J.M. Floryan. and 11, Rasmusscn. Al'pl. Mech. Rt'I'. 42 (1989)

    323.

    G. J.-E Htu. O_M.Gao. A. Garca-Rcjon. and G. Salloum. PolYIn.FII!:. Sei . .'X (1998) l.

    7, F. Ilinca. J.~F Htu. and D. PcJ1cticr. ProCt't'dill[!.so/ tire 13thAlAA Con/en'flcl" AIAA97-1863. Snowmass. ca (June 1997).

    8. J.-F. Htu and F. 1Iinca, Proeeedings o/ he 10th I"tema-tim/(/l Cm,{t'rt'llce m Numaical Ml'tJlOds /or Thermal Probolel1/J. Swansca U.K. (July 1997),

    Rl'I'. A/c.\". F. 45 S1 (1999) 1-5