Flow Analysis of Injection Molds

372 Pages·2013·6.31 MB·English

by  Peter Kennedy

Peter K. Kennedy
Rong Zheng
Flow Analysis of
Injection Molds
2nd Edition
Kennedy, Zheng
Flow Analysis of Injection Molds

Peter Kennedy
Rong Zheng
Flow Analysis of
Injection Molds
2nd Edition
Hanser Publishers, Munich Hanser Publications, Cincinnati
The Authors:
Dr. Peter Kennedy,
Helmet Investments, 141/99 Spring St., Melbourne, Victoria 3000, Australia
Dr. Rong Zheng,
School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, NSW 2006, Australia
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Library of Congress Cataloging-in-Publication Data
Kennedy, Peter (Peter K.)
Flow analysis of injection molds / Peter Kennedy, Rong Zheng. -- 2nd
edition.
pages cm
Includes bibliographical references and index.
ISBN 978-1-56990-512-8 (hardcover) -- ISBN 978-1-56990-522-7 (e-book)
(print) 1. Injection molding of plastics. 2. Mathematical modeling. I. Zheng,
Rong, 1947- II. Title.
TP1150.K45 2012
668.4’120685--dc23
2012025721
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TomyFather
ProfessorZhi-ZhongZheng
forhisloveandprofessionalspirit
thathaveguidedmylife.
—RongZheng
TomyChildren
WilliamandAnthony
fortheirsupport,
understandingandlove.
—PeterK.Kennedy

Acknowledgements
We wish to record our sincere thanks to Professors Roger I. Tanner (University of Sydney),
H.E.H. Meijer (Technische Universiteit Eindhoven), Xi-Jun Fan (University of Sydney), and
NhanPhan-Thien(NationalUniversityofSingapore—formerlyoftheUniversityofSydney).
Manyresultsandideaspresentedinthisbookcamefromtheirworksandfromcollaborative
research work with them and their colleagues. From this book one may see their deep in-
fluenceonourwork. ThanksarealsoduetoProfessorCharlesTucker(UniversityofIllinois,
Urbana-Champaign),ProfessorsGerritPeters,andPatrickAnderson(bothofTechnischeUni-
versiteitEindhoven)forfruitfuldiscussionsandadvicefromwhichwebenefited.
WealsowanttothankourformerMoldflowcolleaguesinMelbourne, AustraliaandIthaca,
USAwithwhomwebothusedtowork.Ourinteractionswiththembroadenedourknowledge
inseveraldifferentaspectsandleadtodeepfriendships. Theirworkcanalsobeseeninthis
book.
MuchofourearlyworkwasconductedwithseveralconsortiumslocatedinFranceandspon-
soredbyMoldflowCorporationandsomeotherindustrialpartners. Inparticular,wewould
liketothankProfessorsG.Regnier(formerlyENSAMParis,nowArtsetMétiersParisTech),R.
Fulchiron(UniversitédeLyon),D.Delaunay(UniversitédeNantes),andDr. V.Leo(Solvay)
forparticipationinseveralprojectsthatshowedhowcomplextheinjectionmoldingprocessis
butneverthelessproducedsomeresultsthatareofpracticaluse.
WeareindebtedtotheAustralianCooperativeResearchCenterforPolymersforprovidingan
opportunity of doing collaborative research with research teams from Monash and Sydney
Universities.Inparticular,weweregratefultoobtainaccesstotheAustralianSynchrotron.
SpecialthanksgototheformerMoldflowCorporation(nowpartofAutodeskInc.)forprovid-
inganexcellentworkingenvironmentandconstantsupporttobothofusduringtheperiodwe
wereworkingthere.
Professors H.E.H. Meijer, Nhan Phan-Thien, and Roger I. Tanner reviewed the draft of the
wholebookandmadeveryvaluablecommentsandsuggestionsforimprovement;theirhelp
isgratefullyacknowledged.
Wealsowishtothanktheeditorsofthisbook’spublisherfortheirpatienceandprofessional
assistance.
Onthepersonalside,wewanttothankourfamiliesforthelove,understanding,andencour-
agementthatsustainedusduringourconfrontationwithanimportant,butdifficult,industrial
problem.

Preface
Injection molding is an ideal process for fabricating large numbers of geometrically com-
plexparts. Manyeverydayitemsareinjectionmolded: mobilephonehousings,automobile
bumpers, television cabinets, compact discs, and lunch boxes are all examples of injection
moldedparts.Partsproducedbytheprocessarealsobecomingcommonplaceinlessobvious
applications.Forexample,therelativelynewareaofmicro-injectionmoldingisprovidingnew
methodsofdrugdeliveryandopticalcouplers[195].
Variationsofinjectionmoldingthathavebeendevelopedovertheyearsincludeco-injection
ortwo-componentmolding,waterinjection,andgas-assistedinjectionmolding(GAIM).All
theseprocessesprovideadditionalscopefordesignersofplasticparts.Excellentexamplesare
provided by Neerincx [267] and Neerincx et al. [268,269]. Indeed it is possible to combine
thesevariationswitheachotherorinjectionmoldingtoachieveotherprocesses.Inparticular,
NeerincxandMeijercombinedGAIMandtwo-componentmolding[270]toproduceapart
withuniquequalities.
Animportantcharacteristicofinjectionmolding, includingvariations, isthatitmaynotbe
possibletofixapartdefectinproductionbysimplyvaryingprocessconditions. Frequently
themoldmustbemodifiedtoovercomeaproblem.Thisisexpensiveandcostsvaluabletime.
Itisfarbettertoavoidproblemsinthedesignphasethantofixtheminproduction. Conse-
quentially,simulationofinjectionmoldingisindustriallyvaluable.
Notsurprisingly,thereareseveralcommercialcompaniesofferingsoftwareforsimulationof
injectionmoldinganditsvariants. Duetothecomplexityofthephysicsoftheprocess,vari-
ousassumptionsaremadetosimplifythemathematicalmodelusedforsimulation. Overthe
yearsmanydescriptionsofmodelingandsimulationofinjectionmoldinghaveappearedin
academicjournalsandbooks. Whilereadilyavailabletospecialistreaders,anunderstanding
ofprinciplesusedinsimulationsoftwareisdifficultfornonspecialiststoobtain. Thisisdue
tothemulti-disciplinarynatureofsimulationsoftware.Inparticular,aspectsofrheology,ma-
terialsscience,andnumericalmethodsareused. Therearesomeexcellentbooksonpolymer
processing that discuss injection molding. One of the original classics was by Tadmor and
Gogos[351]. ThiswasfollowedbyTucker’sbook[368]whichfocusedonmodelingforcom-
putersimulation. Morerecently, OsswaldandHernández-Ortiz[279]providedanoverview
ofmodelingandsimulationforpolymerprocessing,whileKamaletal.[190]haveproduceda
bookfocusedoninjectionmoldingthatdiscussesvariationsandotheraspectsoftheinjection
moldingprocess.
Giventheimportanceofinjectionmoldingasaprocess,andthesimulationindustrythathas
growntosupportit,webelievethereisaneedforabookthatdealssolelywithmodelingand
simulationofinjectionmolding. Oneoftheauthorswroteabookin1995[196]alongthese
lines. Itdiscussedfillingandpackingphasesimulation,butisnolongerinprint. Moreover,
therehavebeenmanydevelopmentsinmodelingandsimulationsincethattime.
Thecurrentbookisintendedtoaddressthisneed.Itprovidesacomprehensivedescriptionof
modelingandsimulationofinjectionmolding.Whilesomepartsofthebookmayberelevant