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ASTM Publishes Electroplating Standards Specifically for Threaded Fasteners

In1998theAmericanSocietyforTestingandMaterials(ASTM)firstissuedASTMF1941entitledStandardSpecificationforElectrodepositedCoatingsonThreadedFasteners(UnifiedScrewThreads,UN/UNR).InJanuaryofthisyearthe2001ASTMStandardsBook,Volume01.08waspublishedcontainingarevisedversionofthisstandardplusacomparablestandardtocovermetricthreadedfasteners.ThenewstandardisASTMF1941M-00entitledStandardSpecificationforElectrodepositedCoatingsonThreadedFasteners(Metric).

Thesetwostandardsareapplicableonlytothreadedfasteners.Thesespecificationscoverelectrodepositedzinc,cadmium,zinccobaltalloy,zincnickelalloyandzincironalloyfinishesastheyrelatetothreadedfasteners.Thespecificationprovidesfourminimumthicknessdesignationsrangingfrom.0001to.0005inches(3to12)andlistsfivedifferenttypesofchromatefinishesthatcanbeaddedtotheelectrodepositedplatingstoincreasetheplatingscorrosionresistance.

ASTMF1941andASTMF1941Maddressseveralspecificissuesrelatedtothreadedfastenersthatwilleliminatemuchofthepastconfusionresultingfromtheelectroplatingofthreadedfasteners.Theseimportantissuesare:theexplanationofwheretotestplatingthickness,threadfitrequirements,bakingandtestingforhydrogenem-brittlementriskmanagement,andcorrosionresistancerequirements. Inspect Plating Thickness On Significant Surfaces

Manydisagreementsregardingplatingthicknesshaveresultedfromcustomersmeasuringthicknessinonelocationandtheirsuppliersmeasuringinanother.Electrodepositedfinishesdonotapplyuniformlyonallareasofapart.Electrodepositedfinishesarethickeronthepartsextremeendsandonedges.Becauseofthisnaturallackofuniformdeposition,itisextremelyimportantthatcustomersandsuppliersmeasureplatingthicknessinthesamelocationsonfastenerssothattestresultscanbeagreedupon.

ASTMF1941andASTMF1941Mstatethatplatingthicknessmustbemeasuredonsignificantsurfaces.ThistermisdefinedasfollowsinSection3.1.4:

Significantsurface-significantsurfacesareareaswheretheminimumthicknesstobemetshallbedes-ignatedontheapplicabledrawingorbytheprovisionofasuitablymarkedsample.However,ifnotdesignated,significantsurfacesshallbedefinedasthosenormallyvisible,directlyorbyreflection,whichareessentialtotheappearanceorserviceabilityofthefastenerwhenassembledinnormalposition,orwhichcanbethesourceofcorro-sionproductsthatdefacevisiblesurfacesontheassembledfastener.(Figure1)and(Figure2)illustratesignificantsurfacesonstandardexternallyandinternallythreadedfasteners.

INDUSTRIAL FASTENERS INSTITUTE6363 Oak Tree Boulevard Independence, Ohio 44131 USA, www.indfast.org

Allstandardsandspecificationsareadvisoryonly.Theirusebyanyoneisentirelyvoluntary.Reliancethereonforanypurposebyanyoneisatthesoleriskofthatpersonortheuseroftheproduct,andtheIFIisnotresponsibleforanyloss,claim,ordamagearisingtherefrom.Informulatingandapprovingstandardsandspecifications,theIFIhasnotinvestigatedandwillnotinvestigatepatentswhichmayapplytothesubjectmatter.Prospectiveusersofthestandardsandspecificationsareresponsibleforadvisingthemselvesofandprotectingthemselvesagainstanypatentinfringementliabilitywhichmayariseoutofsuchuse. INDUSTRIALFASTENERSINSTITUTE2008

PublishedandissuedbytheIndustrialFastenersInstituteofIndependence,OH

Issued:March,2001

IFIASTMPublishesElectroplatingStandardsSpecificallyforThreadedFasteners

IFITechnicalBulletin

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Proper Thread Gauging Before And After Plating

Threadfitisacriticalissueforthreadedfastenersbecauseover-platingthreadedpartscanresultincompo-nentsthatwillnotassembletogether.

InchThreads:ASTMF1941coversthreadfitrequirementsinchthreadsinthefollowingtwoparagraphs:

6.3.1.2External Threads -Maximumcoatingthicknessathighcurrentdensitythreadedtipsmustprovideforclass3AGOacceptancegaugeacceptance.

6.3.1.3Internal Threads-Maximumcoatingthicknessofinternalthreadsmustprovideforclass1B,2B,or3BGothreadacceptance.

ASTMF1941alsoprovidesahelpfulchartinAnnexX3thatindicatesthemaximumplatingthicknessthatcanbeappliedtoclass1Aand2Athreadsofallpitcheswithoutexceedingthe3AGOgagingrequirementsafterplating.TheAppendixsectionX3.2makesanoftenconfusedissueveryclearbyspecificallystatingthatinchthreads,whichare2Abeforeplating,aregagedusingClass3AGogagesand2ANot-Gogaugesafterplating.

MetricThreads:ASTMF1941Mcoversthreadfitrequirementsmetricthreadsinthefollowingtwopara-graphs:

6.3.1.2External Threads-Maximumcoatingthicknessathighcurrentdensitythreadedtipsmustprovideforbasic(tolerancepositionh)GOacceptancegaugeacceptance.Therefore,thethreadaftercoatingissubjecttoacceptanceusinga6hGOgaugeforplated6gclassexternalthreadsand4h6hGOgaugeforplated4g6gexternalthreadsrespectively.

6.3.1.3 Internal Threads-Maximumcoatingthicknessofinternalthreadsmustprovideforbasic(tolerancepositionH)Gothreadacceptance.Therefore,thethreadaftercoatingissubjecttoacceptanceusingaclass6HGOgaugefor6Hclassinternalthreads.

ASTMF1941MalsoprovidesTableX3.1inAppendixX3thatindicatesthemaximumplatingthicknessthatcanbeappliedtoclass6gand4g6gcoarsepitchthreadswithoutexceedingthe6hor4h6hGOgagingrequirementsafterplatingrespectively.TheAppendixsectionX3.3makesanoften-confusedissueveryclearbyspecificallystatingthatmetricthreads,whichare6gbeforeplating,aregagedusingClass6hGogagesand6gNot-Gogagesafterplat-ing.

Risk Management Issues For Hydrogen Embrittlement

Section6.4ofbothASTMF1941andF1941Mcoverhydrogenembrittlementissuesverythoroughly.Thissectionmakesthefollowingpoints:

FastenershavinghardnessofRockwellC40andabove,allcasehardenedparts,andpartshavingcaptivated1.hardenedwashersmustbebakedtominimizetheriskofhydrogenembrittlement.Typically,bakingshouldbedonewithin4hoursafterplating,withonehourpreferred.Partsshouldbebakedfor2.2to24hoursatatemperaturebetween350and450degreesF.Thesupplierandpurchasershouldagreeonthespecificbaketimesandtemperaturestobeusedontheirproducts.FastenersaboveRockwellC40mustbetestedunlesstheplatingbathhasbeenqualifiedinaccordancewiththe3.testmethodsinASTMF1940.Theeffectivenessofthebakingprocessinrelievinghydrogenfromthesteelfas-tenersmustbeverifiedusingoneofthetestmethodsinASTMF606,F1624,F519,orNASM1312-5.ThetestingofpartsbelowRockwellC40isnotmandatory.

INDUSTRIAL FASTENERS INSTITUTE6363 Oak Tree Boulevard Independence, Ohio 44131 USA, www.indfast.org

Allstandardsandspecificationsareadvisoryonly.Theirusebyanyoneisentirelyvoluntary.Reliancethereonforanypurposebyanyoneisatthesoleriskofthatpersonortheuseroftheproduct,andtheIFIisnotresponsibleforanyloss,claim,ordamagearisingtherefrom.Informulatingandapprovingstandardsandspecifications,theIFIhasnotinvestigatedandwillnotinvestigatepatentswhichmayapplytothesubjectmatter.Prospectiveusersofthestandardsandspecificationsareresponsibleforadvisingthemselvesofandprotectingthemselvesagainstanypatentinfringementliabilitywhichmayariseoutofsuchuse. INDUSTRIALFASTENERSINSTITUTE2008

PublishedandissuedbytheIndustrialFastenersInstituteofIndependence,OH

IFITechnicalBulletin

Issued:March,2001

IFIASTMPublishesElectroplatingStandardsSpecificallyforThreadedFasteners

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Bakingmustbedonebeforeapplyingchromatefinishestoparts.Temperaturesabove150degreesFwilldam-4.agethechromatesandmakethemineffective.

Performance Requirements For Corrosion Resistance

Section9.3ofASTMF1941andF1941Mstatethatfastenersmustbesubjectedtosaltspraycorrosionresistancetestsonlyifspecificallyrequiredbythecustomerspurchaseorder.Ifpartsarerequiredtopasssaltspraytests,thecorrosionrequirementsonlyapplytothoseareasonthepartsthatmeetthespecificationsdefinitionofsignificantsurface.

Partsarerequiredtoagefor24hoursafterplatingbeforebeingcorrosiontested.ThesaltspraytestingmethodusedmustmeettherequirementsofASTMB117.ThefourtablesinAnnexA1inbothstandardsspecifytheminimumnumberofhoursofsaltsprayresistancethatisrequiredforeachoftheelectrodepositedplatingshavingthevariousthicknesses,andaddedchromatefinishes.Asanexample,.0002inches(5(m)ofzinconsteelwithaclearchromate,designatedasFE/ZN5A,mustwithstand24hoursofsaltsprayresistancebeforeexhibitingredrustwhilethesamethicknessofzincwithanopaque(olivegreen)chromate,designatedasFE/ZN5D,mustwithstand96hoursofsaltsprayresistancebeforeexhibitingredrust.

TheASTMF1941ANDF1941Melectroplatingstandardsarethefirstproducedexclusivelyforthreadedfasteners.Theythoroughlyaddressareasofmisunderstandingthathaveexistedbetweenfastenercustomersandsuppliersinthepast.Fastenersuppliersshouldobtainacopyofthisspecificationimmediatelyandshouldstarttofollowthemwhileurgingtheircustomerstousetheseonfuturepurchaseordersforelectroplatedthreadedfasteners.Thesestandardsareincludedinthe2001Volume01.08oftheASTMStandardsandcanbeobtainedfromtheASTMwebsightatwww.astm.org.

Disclaimer:Allinformationprovidedinthisdocumentand/orpresentationisbasedondatatheIndustrialFastenersInstitutebelievestobereliableandaccurate.Suchinformationisintendedforusebypersonsattheirowndiscretionandrisk.Theinformationhereinisbasedonindustrystandardsandrecognizedpractices.TheIndustrialFastenersInstituteandtherepresentativesprovidingthismaterialassumenoresponsibilityforthecontent.

INDUSTRIAL FASTENERS INSTITUTE6363 Oak Tree Boulevard Independence, Ohio 44131 USA, www.indfast.org

Allstandardsandspecificationsareadvisoryonly.Theirusebyanyoneisentirelyvoluntary.Reliancethereonforanypurposebyanyoneisatthesoleriskofthatpersonortheuseroftheproduct,andtheIFIisnotresponsibleforanyloss,claim,ordamagearisingtherefrom.Informulatingandapprovingstandardsandspecifications,theIFIhasnotinvestigatedandwillnotinvestigatepatentswhichmayapplytothesubjectmatter.Prospectiveusersofthestandardsandspecificationsareresponsibleforadvisingthemselvesofandprotectingthemselvesagainstanypatentinfringementliabilitywhichmayariseoutofsuchuse. INDUSTRIALFASTENERSINSTITUTE2008

PublishedandissuedbytheIndustrialFastenersInstituteofIndependence,OH

IFITechnicalBulletin

Issued:March,2001

IFIASTMPublishesElectroplatingStandardsSpecificallyforThreadedFasteners