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

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

JournalofMaterialsProcessingTechnology1762006273–277Abstractprocedurethemetallographicwith©K1.industrywiththisitidoubtablethetointhetheaityfield,theturingcomposedusinTheir09240136/doiAtechnicalnoteonthecharacterizationofelectroformednickelshellsfortheirapplicationtoinjectionmoldsMarioD.Monzon,M.DoloresMarrero,A.NizardoBenitez,PedroM.Hernandez,J.FranciscoCardenesUniversidaddeLasPalmasdeGranCanaria,DepartamentodeIngenieriaMecanica,SpainReceived19November2003receivedinrevisedform14January2006accepted11April2006Thetechniquesofrapidprototypingandrapidtoolinghavebeenwidelydevelopedduringthelastyears.Inthisarticle,electroformingasatomakecoresforplasticsinjectionmoldsisanalysed.ShellsareobtainedfrommodelsmanufacturedthroughrapidprototypingusingFDMsystem.Themainobjectiveistoanalyzethemechanicalfeaturesofelectroformednickelshells,studyingdifferentaspectsrelatedtotheirstructure,hardness,internalstressesandpossiblefailures,byrelatingthesefeaturestotheparametersofproductionoftheshellsanelectroformingequipment.Finallyacorewastestedinaninjectionmold.2006ElsevierB.V.Allrightsreserved.eywordsElectroplatingElectroformingMicrostructureNickelIntroductionOneofthemostimportantchallengeswithwhichmoderncomesacrossistooffertheconsumerbetterproductsplasticinjectedpieces1–3,however,itistruethatitiswheretheyhavedevelopedmoreandwheretheyfindthehighestoutput.Thispaperisincludedwithinawiderresearchlinewhereitoutstandingvarietyandtimevariabilitynewdesigns.Forreason,modernindustrymustbemoreandmorecompetveandithastoproducewithacceptablecosts.Thereisnothatcombiningthetimevariableandthequalityvariisnoteasybecausetheyfrequentlyconditiononeanothertechnologicaladvancesintheproductivesystemsaregoingpermitthatcombinationtobemoreefficientandfeasibleawaythat,forexample,ifitisobservedtheevolutionofsystemsandtechniquesofplasticsinjection,wearriveatconclusionthat,infact,ittakeslessandlesstimetoputnewproductonthemarketandwithhigherlevelsofqual.Themanufacturingtechnologyofrapidtoolingis,inthisoneofthosetechnologicaladvancesthatmakespossibleimprovementsintheprocessesofdesigningandmanufacinjectedparts.Rapidtoolingtechniquesarebasicallyofacollectionofproceduresthataregoingtoallowtoobtainamoldofplasticparts,insmallormediumseries,ashortperiodoftimeandwithacceptableaccuracylevels.applicationisnotonlyincludedinthefieldofmakingEmailaddressmmonzondim.ulpgc.esM.D.Monzon.attemptstrialstartinganequipment.formingcationswparametersrapidratemethod.2.throughepoxiccoreing–seefrontmatter©2006ElsevierB.V.Allrightsreserved.10.1016/j.jmatprotec.2006.04.003tostudy,define,analyze,testandpropose,ataninduslevel,thepossibilityofcreatingcoresforinjectionmoldsfromobtainingelectroformednickelshells,takingasinitialmodelaprototypemadeinaFDMrapidprototypingItalsowouldhavetosaybeforehandthattheelectrotechniqueisnotsomethingnewbecauseitsappliintheindustryarecountless3,butthisresearchorkhastriedtoinvestigatetowhatextentandunderwhichtheuseofthistechniqueintheproductionofmoldsistechnicallyfeasible.AllmadeinanaccuandsystematizedwayofuseandproposingaworkingManufacturingprocessofaninjectionmoldThecoreisformedbyathinnickelshellthatisobtainedtheelectroformingprocess,andthatisfilledwithanresinwithmetallicchargeduringtheintegrationintheplate4ThismoldFig.1permitsthedirectmanufacturbyinjectionofatypeamultipleusespecimen,astheyare274Processingdefinedspecimentionandtools.researchedabcdeTheformedplaten.processca3.whichwhenbathanmadethethecathodesulf10703tomolds,sulfstressesconditions,aroundalsoisamidealsopermittingoftoharmfultidistribhasM.D.Monzonetal./JournalofMaterialsFig.1.Manufacturedinjectionmoldwithelectroformedcore.bytheUNEENISO3167standard.Thepurposeofthisistodeterminethemechanicalpropertiesofacollecofmaterialsrepresentativeindustry,injectedinthesetoolsitscoMParisonwiththepropertiesobtainedbyconventionalThestagestoobtainacore4,accordingtothemethodologyinthiswork,arethefollowingDesigninCADsystemofthedesiredobject.ModelmanufacturinginarapidprototypingequipmentFDMsystem.ThematerialusedwillbeanABSplastic.Manufacturingofanickelelectroformedshellstartingfromthepreviousmodelthathasbeencoatedwithaconductivepaintbeforehanditmusthaveelectricalconductivity.Removaloftheshellfromthemodel.Productionofthecorebyfillingthebackoftheshellwithepoxyresinresistanttohightemperaturesandwiththerefrigeratingductsmadewithcoppertubes.injectionmoldhadtwocavities,oneofthemwastheelectrocoreandtheotherwasdirectlymachinedinthemovingThus,itwasobtained,withthesametoolandinthesameconditions,toinjectsimultaneouslytwospecimensinvitiesmanufacturedwithdifferenttechnologies.ObtaininganelectroformedshelltheequipmentElectrodeposition5,6isanelectrochemicalprocessinachemicalchangehasitsoriginwithinanelectrolytepassinganelectriccurrentthroughit.Theelectrolyticisformedbymetalsaltswithtwosubmergedelectrodes,anodenickelandacathodemodel,throughwhichitistopassanintensitycomingfromaDCcurrent.Whencurrentflowsthroughthecircuit,themetalionspresentinsolutionaretransformedintoatomsthataresettledonthecreatingamoreorlessuniformdepositlayer.Theplatingbathusedinthisworkisformedbynickelamate7,8ataconcentrationof400ml/l,nickelchlorideg/l,boricacid50g/l,AllbriteSLA30cc/landAllbrite2cc/l.Theselectionofthiscompositionismainlyduethetypeofapplicationweintend,thatistosay,injectionevenwhentheinjectionismadewithfibreglass.Nickelamateallowsustoobtainanacceptablelevelofinternalhahatemperatureifying4.testsformedFig.vfromofperature560conoperateTechnology1762006273–277intheshellthetestsgaveresults,fordifferentprocessnotsuperiorto50MPaandforoptimumconditions2MPa.Nevertheless,suchlevelofinternalpressureisaconsequenceofusingasanadditiveAllbriteSLA,whichastressreducerconstitutedbyderivativesoftoluenesulfonandbyformaldehydeinaqueoussolution.Suchadditivefavourstheincreaseoftheresistanceoftheshellwhenasmallergrain.Allbrite703isanaqueoussolutionbiodegradablesurfaceactingagentsthathasbeenutilizedreducetheriskofpitting.Nickelchloride,inspiteofbeingfortheinternalstresses,isaddedtoenhancetheconducvityofthesolutionandtofavourtheuniformityinthemetallicutioninthecathode.TheboricacidactsasapHbuffer.TheequipmentusedtomanufacturethenickelshellstestedbeenasfollowsPolypropylenetank600mm400mm500mminsize.Threeteflonresistors,eachonewith800W.Mechanicalstirringsystemofthecathode.Systemforrecirculationandfiltrationofthebathformedbyapumpandapolypropylenefilter.Chargingrectifier.Maximumintensityincontinuous50Aandcontinuouscurrentvoltagebetween0and16V.TitaniumbasketwithnickelanodesIncoSRoundsElectrolyticNickelwithapurityof99.Gasesaspirationsystem.Oncethebathhasbeendefined,theoperativeparametersthatvebeenalteredfortestingdifferentconditionsoftheprocess2vebeenthecurrentdensitybetween1and22A/dm,thebetween35and55◦CandthepH,partiallymodthebathcomposition.ObtainedhardnessOneofthemostinterestingconclusionsobtainedduringthehasbeenthatthelevelofhardnessofthedifferentelectroshellshasremainedatratherhighandstablevalues.In2,itcanbeobservedthewayinwhichforcurrentdensityaluesbetween2.5and22A/dm2,thehardnessvaluesrange540and580HV,atpH4±0.2andwithatemperature45◦C.IfthepHofthebathisreducedat3.5andthetemis55◦Cthosevaluesareabove520HVandbelowHV.Thisfeaturemakesthetestedbathdifferentfromotherventionalonescomposedbynickelsulfamate,allowingtowithawiderrangeofvaluesnevertheless,suchoperaFig.2.Hardnessvariationwithcurrentdensity.pH4±0.2,T45◦C.ProcessingTechnology1762006273–277275tistresstainhand,200–250isthemoststeel520–595anickmaterialsoffillingforplasticsshellminimumpitting.5.currentplesperpendicularpreparation,ishedacid15,observPME3ADLarticle,thethelayerapproximatelyzontalThus,thegoingthebemoldsTTSeries1234Fig.3.Series1150,etch1.Fig.4.Series2300,etch2.M.D.Monzonetal./JournalofMaterialsvitywillbelimiteddependingonotherfactors,suchasinternalbecauseitsvariabilitymayconditiontheworkatcervaluesofpH,currentdensityortemperature.OntheotherthehardnessofaconventionalsulfamatebathisbetweenHV,muchlowerthantheoneobtainedinthetests.Itnecessarytotakeintoaccountthat,foraninjectionmold,hardnessisacceptablestartingfrom300HV.Amongtheusualmaterialsforinjectionmoldsitispossibletofindforimprovement290HV,steelforintegralhardeningHV,casehardenedsteel760–800HV,etc.,insuchwaythatitcanbeobservedthatthehardnesslevelsoftheelshellswouldbewithinthemedium–highrangeoftheforinjectionmolds.TheobjectiontothelowductilitytheshelliscompensatedinsuchawaywiththeepoxyresinthatwouldfollowitbecausethisistheoneresponsibleholdinginwardlythepressurechargesoftheprocessesofinjectionthisisthereasonwhyitisnecessaryforthetohaveathicknessashomogeneousaspossibleaboveavalueandwithabsenceofimportantfailuressuchasMetallographicstructureInordertoanalyzethemetallographicstructure,thevaluesofdensityandtemperatureweremainlymodified.Thesamwereanalyzedinfrontalsectionandintransversalsectiontothedeposition.Forachievingaconvenienttheywereconvenientlyencapsulatedinresin,polandetchedindifferentstageswithamixtureofaceticandnitricacid.Theetchesarecarriedoutatintervalsof25,40and50s,afterbeingpolishedagain,inordertobeedafterwardsinametallographicmicroscopeOlympus3.3/10.BeforegoingontocommentthephotographsshowninthisitisnecessarytosaythatthemodelsusedtomanufactureshellsweremadeinaFDMrapidprototypingmachinewheremoltenplasticmaterialABS,thatlatersolidifies,issettledbylayer.Ineachlayer,theextruderdieleavesathread0.15mmindiameterwhichiscompactedhoriandverticallywiththethreadsettledinmediatelyafter.inthesurfaceitcanbeobservedthinlinesthatindicateroadsfollowedbytheheadofthemachine.Theselinesaretoactasareferencetoindicatethereproducibilitylevelofnickelsettled.Thereproducibilityofthemodelisgoingtoafundamentalelementtoevaluateabasicaspectofinjectionthesurfacetexture.ThetestedseriesareindicatedinTable1.able1estedseriespHTemperature◦CCurrentdensityA/dm24.2±0.2552.223.9±0.2455.564.0±0.24510.004.0±0.24522.22firstthatstillalessetchisdarkconditionsFig.3illustratesthesurfaceofasampleoftheseriesaftertheetch.ItshowstheroadsoriginatedbytheFDMmachine,istosaythatthereisagoodreproducibility.Itcannotbenoticedtheroundedgrainstructure.InFig.4,series2,aftersecondetch,itcanbeobservedalineoftheroadinawayclearthaninthepreviouscase.InFig.5,series3and2◦itbeginstoappeartheroundedgrainstructurealthoughitverydifficulttochecktheroadsatthistime.Besides,themostenedareasindicatethepresenceofpittingbyinadequateofprocessandbathcomposition.Fig.5.Series3300,etch2.276Processingandmodelfordeposition,ditionswhatalthoughabosulfnonlaminarvturetheSLA.turecurrent6.applicationDiftiestensiometerwithwidthonlysilestresses.nickintestedforacceptableistionsstresses.M.D.Monzonetal./JournalofMaterialsFig.6.Planetransversalofseries2600,etch2.Thisbehaviorindicatesthat,workingatalowcurrentdensityahightemperature,shellswithagoodreproducibilityoftheandwithasmallgrainsizeareobtained,thatis,adequatetherequiredapplication.IftheanalysisiscarriedoutinaplanetransversaltotheitcanbetestedinallthesamplesandforalltheconthatthegrowthstructureofthedepositislaminarFig.6,isverysatisfactorytoobtainahighmechanicalresistanceattheexpenseofalowductibility.Thisqualityisdue,veall,tothepresenceoftheadditivesusedbecauseanickelamatebathwithoutadditivesnormallycreatesafibrousandstructure9.Themodificationuntilanearlynullalueofthewettingagentgaveasaresultthatthelaminarstrucwasmaintainedinanycase,thatmatterdemonstratedthatdeterminantforsuchstructurewasthestressreducerAllbriteOntheotherhand,itwasalsotestedthatthelaminarstrucvariesaccordingtothethicknessofthelayerintermsofthedensity.InternalstressesOneofthemaincharacteristicthatashellshouldhaveforitslikeaninsertistohavealowlevelofinternalstresses.ferenttestsatdifferentbathtemperaturesandcurrentdensiweredoneandameasuresystemrestedoncathodeflexuralmethodwasused.Asteeltestingcontrolwasusedasidefixedandtheotherfree160mmlength,12.7mmandthickness0.3mm.BecausethemetallicdepositionisinonesidethetestingcontrolhasamechanicalstraintenorcompressivestressthatallowstocalculatetheinternalStoneymodel10wasappliedandwassupposedthatelsubstratumthicknessisenoughsmall3H9262mtoinfluence,anelasticpointofview,tothestrainedsteelpart.Inallthecasesthemostvalueofinternalstresswasunder50MPaextremeconditionsand2MPaforoptimalconditions,anvaluefortherequiredapplication.Theconclusionthattheelectroliticbathallowstoworkatdifferentcondiandparameterswithoutasignificantvariationofinternal7.moplastichasdimensions,calbycore,betweenthematerials.itofenceecrystallinenoticedcore,around8.checkhasertiesthatgoodstructure.becoreplasticReferTechnology1762006273–277Fig.7.Analysisbyphotoelasticityofinjectedspecimens.TestoftheinjectionmoldTestshavebeencarriedoutwithvariousrepresentativethermaterialssuchasPP,PA,HDPEandPC,anditbeenanalysedthepropertiesoftheinjectedpartssuchasweight,resistance,rigidityandductility.Mechanipropertiesweretestedbytensiledestructivetestsandanalysisphotoelasticity.About500injectionswerecarriedoutonthisremainingunderconditionsofwithstandingmanymore.Ingeneralterms,importantdifferenceswerenotnoticedthebehaviorofthespecimensobtainedinthecoreandonesfromthemachinedcavity,forthesetoftheanalysedHoweverintheanalysisbyphotoelasticiyFig.7wasnoticedadifferenttensionalstatebetweenbothtypesspecimens,basicallyduetodifferencesintheheattransferandrigidityoftherespectivemoldcavities.ThisdifferencexplainstheductilityvariationsmoreoutstandinginthepartiallymaterialssuchasHDPEandPA6.ForthecaseofHDPEinalltheanalysedtestedtubesitwasalowerductilityinthespecimensobtainedinthenickelquantifiedabout30.InthecaseofPA6thisvaluewas50.ConclusionsAfterconsecutivetestsandindifferentconditionsithasbeenedthatthenickelsulfamatebath,withtheutilizedadditivesallowedtoobtainnickelshellswithsomemechanicalpropacceptablefortherequiredapplication,injectionmolds,istosay,goodreproducibility,highlevelofhardnessandmechanicalresistanceintermsoftheresultantlaminarThemechanicaldeficienciesofthenickelshellwillpartiallyreplacedbytheepoxyresinthatfinishesshapingthefortheinjectionmold,allowingtoinjectmediumseriesofpartswithacceptablequalitylevels.ences1A.E.W.Rennie,C.E.Bocking,G.R.Bennet,Electroformingofrapidprototypingmandrelsforelectrodischargemachiningelectrodes,J.Mater.Process.Technol.1102001186–196.2P.K.D.V.Yarlagadda,I.P.Ilyas,P.Chrstodoulou,Developmentofrapidtoolingforsheetmetaldrawingusingnickelelectroformingandstereolithographyprocesses,J.Mater.Process.Technol.1112001286–294.

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