外文资料--A technical note on the characterization of electroformed.pdf

JournalofMaterialsProcessingTechnology176(2006)273277AbstractprocedurethemetallographicwithK1.industrywiththisitidoubtablethetointhetheaityfield,theturingcomposedusinTheir0924-0136/$doi:AtechnicalnoteonthecharacterizationofelectroformednickelshellsfortheirapplicationtoinjectionmoldsMarioD.Monzon,M.DoloresMarrero,A.NizardoBenitez,PedroM.Hernandez,J.FranciscoCardenesUniversidaddeLasPalmasdeGranCanaria,DepartamentodeIngenieriaMecanica,SpainReceived19November2003；receivedinrevisedform14January2006；accepted11April2006Thetechniquesofrapidprototypingandrapidtoolinghavebeenwidelydevelopedduringthelastyears.Inthisarticle,electroformingasatomakecoresforplasticsinjectionmoldsisanalysed.ShellsareobtainedfrommodelsmanufacturedthroughrapidprototypingusingFDMsystem.Themainobjectiveistoanalyzethemechanicalfeaturesofelectroformednickelshells,studyingdifferentaspectsrelatedtotheirstructure,hardness,internalstressesandpossiblefailures,byrelatingthesefeaturestotheparametersofproductionoftheshellsanelectroformingequipment.Finallyacorewastestedinaninjectionmold.2006ElsevierB.V.Allrightsreserved.eywords:Electroplating；Electroforming；Microstructure；NickelIntroductionOneofthemostimportantchallengeswithwhichmoderncomesacrossistooffertheconsumerbetterproductsplasticinjectedpieces13,however,itistruethatitiswheretheyhavedevelopedmoreandwheretheyfindthehighestoutput.Thispaperisincludedwithinawiderresearchlinewhereitoutstandingvarietyandtimevariability(newdesigns).Forreason,modernindustrymustbemoreandmorecompet-veandithastoproducewithacceptablecosts.Thereisnothatcombiningthetimevariableandthequalityvari-isnoteasybecausetheyfrequentlyconditiononeanother；technologicaladvancesintheproductivesystemsaregoingpermitthatcombinationtobemoreefficientandfeasibleawaythat,forexample,ifitisobservedtheevolutionofsystemsandtechniquesofplasticsinjection,wearriveatconclusionthat,infact,ittakeslessandlesstimetoputnewproductonthemarketandwithhigherlevelsofqual-.Themanufacturingtechnologyofrapidtoolingis,inthisoneofthosetechnologicaladvancesthatmakespossibleimprovementsintheprocessesofdesigningandmanufac-injectedparts.Rapidtoolingtechniquesarebasicallyofacollectionofproceduresthataregoingtoallowtoobtainamoldofplasticparts,insmallormediumseries,ashortperiodoftimeandwithacceptableaccuracylevels.applicationisnotonlyincludedinthefieldofmakingE-mailaddress:mmonzondim.ulpgc.es(M.D.Monzon).attemptstrialstartinganequipment.formingcationswparametersrapidratemethod.2.throughepoxiccoreingseefrontmatter2006ElsevierB.V.Allrightsreserved.10.1016/j.jmatprotec.2006.04.003tostudy,define,analyze,testandpropose,atanindus-level,thepossibilityofcreatingcoresforinjectionmoldsfromobtainingelectroformednickelshells,takingasinitialmodelaprototypemadeinaFDMrapidprototypingItalsowouldhavetosaybeforehandthattheelectro-techniqueisnotsomethingnewbecauseitsappli-intheindustryarecountless3,butthisresearchorkhastriedtoinvestigatetowhatextentandunderwhichtheuseofthistechniqueintheproductionofmoldsistechnicallyfeasible.Allmadeinanaccu-andsystematizedwayofuseandproposingaworkingManufacturingprocessofaninjectionmoldThecoreisformedbyathinnickelshellthatisobtainedtheelectroformingprocess,andthatisfilledwithanresinwithmetallicchargeduringtheintegrationintheplate4Thismold(Fig.1)permitsthedirectmanufactur-byinjectionofatypeamultipleusespecimen,astheyare274Processingdefinedspecimentionandtools.researched(a)(b)(c)(d)(e)Tcessca3.whichwhenbathanmadethethecathodesulf(10703tomolds,sulfstressesconditions,aroundalsoisamidealsopermittingoftoharmfultidistribhasM.D.Monzonetal./JournalofMaterialsFig.1.Manufacturedinjectionmoldwithelectroformedcore.bytheUNE-ENISO3167standard.Thepurposeofthisistodeterminethemechanicalpropertiesofacollec-ofmaterialsrepresentativeindustry,injectedinthesetoolsitscoMParisonwiththepropertiesobtainedbyconventionalThestagestoobtainacore4,accordingtothemethodologyinthiswork,arethefollowing:DesigninCADsystemofthedesiredobject.Modelmanufacturinginarapidprototypingequipment(FDMsystem).ThematerialusedwillbeanABSplastic.Manufacturingofanickelelectroformedshellstartingfromthepreviousmodelthathasbeencoatedwithaconductivepaintbeforehand(itmusthaveelectricalconductivity).Removaloftheshellfromthemodel.Productionofthecorebyfillingthebackoftheshellwithepoxyresinresistanttohightemperaturesandwiththerefrigeratingductsmadewithcoppertubes.injectionmoldhadtwocavities,oneofthemwastheelectro-coreandtheotherwasdirectlymachinedinthemovingThus,itwasobtained,withthesametoolandinthesameconditions,toinjectsimultaneouslytwospecimensinvitiesmanufacturedwithdifferenttechnologies.Obtaininganelectroformedshell:theequipmentElectrodeposition5,6isanelectrochemicalprocessinachemicalchangehasitsoriginwithinanelectrolytepassinganelectriccurrentthroughit.Theelectrolyticisformedbymetalsaltswithtwosubmergedelectrodes,anode(nickel)andacathode(model),throughwhichitistopassanintensitycomingfromaDCcurrent.Whencurrentflowsthroughthecircuit,themetalionspresentinsolutionaretransformedintoatomsthataresettledonthecreatingamoreorlessuniformdepositlayer.Theplatingbathusedinthisworkisformedbynickelamate7,8ataconcentrationof400ml/l,nickelchlorideg/l),boricacid(50g/l),AllbriteSLA(30cc/l)andAllbrite(2cc/l).Theselectionofthiscompositionismainlyduethetypeofapplicationweintend,thatistosay,injectionevenwhentheinjectionismadewithfibreglass.Nickelamateallowsustoobtainanacceptablelevelofinternalhahatemperatureifying4.testsformedFig.vfromofperature560conoperateTechnology176(2006)273277intheshell(thetestsgaveresults,fordifferentprocessnotsuperiorto50MPaandforoptimumconditions2MPa).Nevertheless,suchlevelofinternalpressureisaconsequenceofusingasanadditiveAllbriteSLA,whichastressreducerconstitutedbyderivativesoftoluenesulfon-andbyformaldehydeinaqueoussolution.Suchadditivefavourstheincreaseoftheresistanceoftheshellwhenasmallergrain.Allbrite703isanaqueoussolutionbiodegradablesurface-actingagentsthathasbeenutilizedreducetheriskofpitting.Nickelchloride,inspiteofbeingfortheinternalstresses,isaddedtoenhancetheconduc-vityofthesolutionandtofavourtheuniformityinthemetallicutioninthecathode.TheboricacidactsasapHbuffer.Theequipmentusedtomanufacturethenickelshellstestedbeenasfollows:Polypropylenetank:600mm400mm500mminsize.Threeteflonresistors,eachonewith800W.Mechanicalstirringsystemofthecathode.Systemforrecirculationandfiltrationofthebathformedbyapumpandapolypropylenefilter.Chargingrectifier.Maximumintensityincontinuous50Aandcontinuouscurrentvoltagebetween0and16V.Titaniumbasketwithnickelanodes(IncoS-RoundsElec-trolyticNickel)withapurityof99%.Gasesaspirationsystem.Oncethebathhasbeendefined,theoperativeparametersthatvebeenalteredfortestingdifferentconditionsoftheprocess2vebeenthecurrentdensity(between1and22A/dm),the(between35and55C)andthepH,partiallymod-thebathcomposition.ObtainedhardnessOneofthemostinterestingconclusionsobtainedduringthehasbeenthatthelevelofhardnessofthedifferentelectro-shellshasremainedatratherhighandstablevalues.In2,itcanbeobservedthewayinwhichforcurrentdensityaluesbetween2.5and22A/dm2,thehardnessvaluesrange540and580HV,atpH40.2andwithatemperature45C.IfthepHofthebathisreducedat3.5andthetem-is55Cthosevaluesareabove520HVandbelowHV.Thisfeaturemakesthetestedbathdifferentfromotherventionalonescomposedbynickelsulfamate,allowingtowithawiderrangeofvalues；nevertheless,suchopera-Fig.2.Hardnessvariationwithcurrentdensity.pH40.2,T=45C.ProcessingTechnology176(2006)273277275tistresstainhand,200250isthemoststeel(520595anickmaterialsoffillingforplasticsshellminimumpitting.5.currentples(perpendicularpreparation,ishedacid15,observPME3-ADLarticle,thethelayerapproximatelyzontalThus,thegoingthebemolds:TTSeries1234Fig.3.Series1(150),etch1.Fig.4.Series2(300),etch2.M.D.Monzonetal./JournalofMaterialsvitywillbelimiteddependingonotherfactors,suchasinternalbecauseitsvariabilitymayconditiontheworkatcer-valuesofpH,currentdensityortemperature.OntheotherthehardnessofaconventionalsulfamatebathisbetweenHV,muchlowerthantheoneobtainedinthetests.Itnecessarytotakeintoaccountthat,foraninjectionmold,hardnessisacceptablestartingfrom300HV.Amongtheusualmaterialsforinjectionmoldsitispossibletofindforimprovement(290HV),steelforintegralhardeningHV),casehardenedsteel(760800HV),etc.,insuchwaythatitcanbeobservedthatthehardnesslevelsoftheelshellswouldbewithinthemediumhighrangeoftheforinjectionmolds.Theobjectiontothelowductilitytheshelliscompensatedinsuchawaywiththeepoxyresinthatwouldfollowitbecausethisistheoneresponsibleholdinginwardlythepressurechargesoftheprocessesofinjection；thisisthereasonwhyitisnecessaryforthetohaveathicknessashomogeneousaspossible(aboveavalue)andwithabsenceofimportantfailuressuchasMetallographicstructureInordertoanalyzethemetallographicstructure,thevaluesofdensityandtemperatureweremainlymodified.Thesam-wereanalyzedinfrontalsectionandintransversalsectiontothedeposition).Forachievingaconvenienttheywereconvenientlyencapsulatedinresin,pol-andetchedindifferentstageswithamixtureofaceticandnitricacid.Theetchesarecarriedoutatintervalsof25,40and50s,afterbeingpolishedagain,inordertobeedafterwardsinametallographicmicroscopeOlympus3.3/10.BeforegoingontocommentthephotographsshowninthisitisnecessarytosaythatthemodelsusedtomanufactureshellsweremadeinaFDMrapidprototypingmachinewheremoltenplasticmaterial(ABS),thatlatersolidifies,issettledbylayer.Ineachlayer,hesurfaceitcanbeobservedthinlinesthatindicateroadsfollowedbytheheadofthemachine.Theselinesaretoactasareferencetoindicatethereproducibilitylevelofnickelsettled.Thereproducibilityofthemodelisgoingtoafundamentalelementtoevaluateabasicaspectofinjectionthesurfacetexture.ThetestedseriesareindicatedinTable1.able1estedseriespHTemperature(C)Currentdensity(A/dm2)4.20.25455.564.00.24510.004.00.24522.22firstthatstillalessetchisdarkconditionsFig.3illustratesthesurfaceofasampleoftheseriesaftertheetch.ItshowstheroadsoriginatedbytheFDMmachine,istosaythatthereisagoodreproducibility.Itcannotbenoticedtheroundedgrainstructure.InFig.4,series2,aftersecondetch,itcanbeobservedalineoftheroadinawayclearthaninthepreviouscase.InFig.5,series3and2itbeginstoappeartheroundedgrainstructurealthoughitverydifficulttochecktheroadsatthistime.Besides,themostenedareasindicatethepresenceofpittingbyinadequateofprocessandbathcomposition.Fig.5.Series3(300),etch2.276Processingandmodelfordeposition,ditionswhatalthoughabosulfnon-laminarvturetheSLA).turecurrent6.applicationDiftiestensiometerwithwidthonlysilestresses.nickintestedforacceptableistionsstresses.M.D.Monzonetal./JournalofMaterialsFig.6.Planetransversalofseries2(600),etch2.Thisbehaviorindicatesthat,workingatalowcurrentdensityahightemperature,shellswithagoodreproducibilityoftheandwithasmallgrainsizeareobtained,thatis,adequatetherequiredapplication.Iftheanalysisiscarriedoutinaplanetransversaltotheitcanbetestedinallthesamplesandforallthecon-thatthegrowthstructureofthedepositislaminar(Fig.6),isverysatisfactorytoobtainahighmechanicalresistanceattheexpenseofalowductibility.Thisqualityisdue,veall,tothepresenceoftheadditivesusedbecauseanickelamatebathwithoutadditivesnormallycreatesafibrousandstructure9.Themodificationuntilanearlynullalueofthewettingagentgaveasaresultthatthelaminarstruc-wasmaintainedinanycase,thatmatterdemonstratedthatdeterminantforsuchstructurewasthestressreducer(AllbriteOntheotherhand,itwasalsotestedthatthelaminarstruc-variesaccordingtothethicknessofthelayerintermsofthedensity.InternalstressesOneofthemaincharacteristicthatashellshouldhaveforitslikeaninsertistohavealowlevelofinternalstresses.ferenttestsatdifferentbathtemperaturesandcurrentdensi-weredoneandameasuresystemrestedoncathodeflexuralmethodwasused.Asteeltestingcontrolwasusedasidefixedandtheotherfree(160mmlength,12.7mmandthickness0.3mm).Becausethemetallicdepositionisinonesidethetestingcontrolhasamechanicalstrain(ten-orcompressivestress)thatallowstocalculatetheinternalStoneymodel10wasappliedandwassupposedthatelsubstratumthicknessisenoughsmall(3H9262m)toinfluence,anelasticpointofview,tothestrainedsteelpart.Inallthecasesthemostvalueofinternalstresswasunder50MPaextremeconditionsand2MPaforoptimalconditions,anvaluefortherequiredapplication.Theconclusionthattheelectroliticbathallowstoworkatdifferentcondi-andparameterswithoutasignificantvariationofinternal7.moplastichasdimensions,calbycore,betweenthematerials.itofenceecrystallinenoticedcore,around8.checkhasertiesthatgoodstructure.becoreplasticReferTechnology176(2006)273277Fig.7.Analysisbyphotoelasticityofinjectedspecimens.TestoftheinjectionmoldTestshavebeencarriedoutwithvariousrepresentativether-materialssuchasPP,PA,HDPEandPC,anditbeenanalysedthepropertiesoftheinjectedpartssuchasweight,resistance,rigidityandductility.Mechani-propertiesweretestedbytensiledestructivetestsandanalysisphotoelasticity.About500injectionswerecarriedoutonthisremainingunderconditionsofwithstandi