ASTM D2240-2005 R2010

Designation:D2240–05(Reapproved2010)StandardTestMethodforRubberProperty—DurometerHardness1ThisstandardisissuedunderthefixeddesignationD2240;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.ThisstandardhasbeenapprovedforusebyagenciesoftheDepartmentofDefense.1.Scope1.1Thistestmethodcoverstwelvetypesofrubberhardnessmeasurementdevicesknownasdurometers:TypesA,B,C,D,DO,E,M,O,OO,OOO,OOO-S,andR.Theprocedurefordeterminingindentationhardnessofsubstancesclassifiedasthermoplasticelastomers,vulcanized(thermoset)rubber,elas-tomericmaterials,cellularmaterials,gel-likematerials,andsomeplasticsisalsodescribed.1.2Thistestmethodisnotequivalenttootherindentationhardnessmethodsandinstrumenttypes,specificallythosedescribedinTestMethodD1415.1.3Thistestmethodisnotapplicabletothetestingofcoatedfabrics.1.4Allmaterials,instruments,orequipmentusedforthedeterminationofmass,force,ordimensionshallhavetrace-abilitytotheNationalInstituteforStandardsandTechnology,orotherinternationallyrecognizedorganizationsparallelinnature.1.5ThevaluesstatedinSIunitsaretoberegardedasstandard.Thevaluesgiveninparenthesesareforinformationonly.ManyofthestateddimensionsinSIaredirectconver-sionsfromtheU.S.CustomarySystemtoaccommodatetheinstrumentation,practices,andproceduresthatexistedpriortotheMetricConversionActof1975.1.6Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafetyandhealthpracticesanddeterminetheapplica-bilityofregulatorylimitationspriortouse.2.ReferencedDocuments2.1ASTMStandards:2D374TestMethodsforThicknessofSolidElectricalInsu-lationD618PracticeforConditioningPlasticsforTestingD785TestMethodforRockwellHardnessofPlasticsandElectricalInsulatingMaterialsD1349PracticeforRubber—StandardTemperaturesforTestingD1415TestMethodforRubberProperty—InternationalHardnessD4483PracticeforEvaluatingPrecisionforTestMethodStandardsintheRubberandCarbonBlackManufacturingIndustriesF1957TestMethodforCompositeFoamHardness-DurometerHardness2.2ISOStandard:3ISO/IEC17025:1999GeneralRequirementsfortheCom-petenceofTestingandCalibrationLaboratories3.SummaryofTestMethod3.1Thistestmethodpermitshardnessmeasurementsbasedoneitherinitialindentationorindentationafteraspecifiedperiodoftime,orboth.Durometerswithmaximumreadingindicatorsusedtodeterminemaximumhardnessvaluesofamaterialmayyieldlowerhardnesswhenthemaximumindi-catorisused.3.2TheproceduresforTypeM,ormicrohardnessdurom-eters,accommodatespecimensthatare,bytheirdimensionsorconfiguration,ordinarilyunabletohavetheirdurometerhard-nessdeterminedbytheotherdurometertypesdescribed.TypeMdurometersareintendedforthetestingofspecimenshavingathicknessorcross-sectionaldiameterof1.25mm(0.050in.)orgreater,althoughspecimensoflesserdimensionsmaybesuccessfullyaccommodatedundertheconditionsspecifiedinSection6,andhaveaTypeMdurometerhardnessrangebetween20and90.Thosespecimenswhichhaveadurometerhardnessrangeotherthanspecifiedshalluseanothersuitableprocedurefordeterminingdurometerhardness.4.SignificanceandUse4.1Thistestmethodisbasedonthepenetrationofaspecifictypeofindentorwhenforcedintothematerialunderspecifiedconditions.Theindentationhardnessisinverselyrelatedtothe1ThistestmethodisunderthejurisdictionofASTMCommitteeD11onRubberandisthedirectresponsibilityofSubcommitteeD11.10onPhysicalTesting.CurrenteditionapprovedJan.1,2010.PublishedApril2010.Originallyapprovedin1964.Lastpreviouseditionapprovedin2005asD2240–05.DOI:10.1520/D2240-05R10.2ForreferencedASTMstandards,visittheASTMwebsite,www.astm.org,orcontactASTMCustomerServiceatservice@astm.org.ForAnnualBookofASTMStandardsvolumeinformation,refertothestandard’sDocumentSummarypageontheASTMwebsite.3AvailablefromInternationalOrganizationforStandardization(ISO),1ruedeVarembé,Casepostale56,CH-1211,Geneva20,Switzerland.1Copyright©ASTMInternational,100BarrHarborDrive,POBoxC700,WestConshohocken,PA19428-2959,UnitedStates.penetrationandisdependentontheelasticmodulusandviscoelasticbehaviorofthematerial.Thegeometryoftheindentorandtheappliedforceinfluencethemeasurementssuchthatnosimplerelationshipexistsbetweenthemeasure-mentsobtainedwithonetypeofdurometerandthoseobtainedwithanothertypeofdurometerorotherinstrumentsusedformeasuringhardness.Thistestmethodisanempiricaltestintendedprimarilyforcontrolpurposes.Nosimplerelationshipexistsbetweenindentationhardnessdeterminedbythistestmethodandanyfundamentalpropertyofthematerialtested.Forspecificationpurposes,itisrecommendedthatTestMethodD785beusedformaterialsotherthanthosedescribedin1.1.5.Apparatus5.1HardnessMeasuringApparatus,orDurometer,andanOperatingStand,Type1,Type2,orType3(see5.1.2)consistingofthefollowingcomponents:5.1.1Durometer:5.1.1.1PresserFoot,theconfigurationandthetotalareaofadurometerpresserfootmayproducevaryingresultswhentherearesignificantdifferencesbetweenthem.Itisrecom-mendedthatwhencomparingdurometerhardnessdetermina-tionsofthesametype(see4.1),thatthecomparisonsbebetweendurometersofsimilarpresserfootconfigurationsandtotalarea,andthatthepresserfootconfigurationandsizebenotedintheHardnessMeasurementReport(see10.2.4and5.1.1.3).5.1.1.2PresserFoot,TypesA,B,C,D,DO,E,O,OO,OOO,andOOO-S,withanorifice(toallowfortheprotrusionoftheindentor)havingadiameterasspecifiedinFig.1(a,b,c,d,e,f,andg),withthecenteraminimumof6.0mm(0.24in.)fromanyedgeofthefoot.Whenthepresserfootisnotofaflatcirculardesign,theareashallnotbelessthan500mm2(19.7in.2).NOTE1—TheTypeOOOandtheTypeOOO-S,designatedherein,differintheirindentorconfiguration,springforce,andtheresultsobtained.SeeTable1andFig.1(eandg).5.1.1.3PresserFoot—flatcirculardesignsdesignatedasTypexR,wherexisthestandarddurometerdesignationandRindicatestheflatcircularpressfootdescribedherein,forexample,TypeaR,dR,andthelike.Thepresserfoot,havingacentrallylocatedorifice(toallowfortheprotrusionoftheindentor)ofadiameterasspecifiedinFig.1(athroughg).Theflatcircularpresserfootshallbe1860.5mm(0.7160.02in.)indiameter.Thesedurometertypesshallbeusedinanoperatingstand(see5.1.2).(a)Durometershavingapresserfootconfigurationotherthanthatindicatedin5.1.1.3shallnotusetheTypexRdesignation,anditisrecommendedthattheirpresserfootconfigurationandsizebestatedintheHardnessMeasurementReport(see10.2.4).5.1.1.4PresserFoot,TypeM,withacentrallylocatedorifice(toallowfortheprotrusionoftheindentor),havingadiameterasspecifiedinFig.1(d),withthecenteraminimumof1.60mm(0.063in.)fromanyedgeoftheflatcircularpresserfoot.TheTypeMdurometershallbeusedinaType3operatingstand(see5.1.2.4).5.1.1.5Indentor,formedfromsteelrodandhardenedto500HV10andshapedinaccordancewithFig.1(a,b,c,d,e,org),polishedoverthecontactareasothatnoflawsarevisibleunder203magnification,withanindentorextensionof2.5060.04mm(0.09860.002in.).5.1.1.6Indentor,TypeOOO-S,formedfromsteelrodandhardenedto500HV10,shapedinaccordancewithFig.1(f),polishedoverthecontactareasothatnoflawsarevisibleunder203magnification,withanindentorextensionof5.0060.04mm(0.19860.002in.).5.1.1.7Indentor,TypeM,formedfromsteelrodandhard-enedto500HV10andshapedinaccordancewithFig.1(d),polishedoverthecontactareasothatnoflawsarevisibleunder503magnification,withanindentorextensionof1.2560.02mm(0.04960.001in.).5.1.1.8IndentorExtensionIndicator,analogordigitalelec-tronic,havingadisplaythatisaninversefunctionoftheindentorextensionsothat:(1)Thedisplayshallindicatefrom0to100withnolessthan100equaldivisionsthroughouttherangeatarateofonehardnesspointforeach0.025mm(0.001in.)ofindentormovement,FIG.1(a)TypeAandCIndentorD2240–05(2010)2--``,,```,``,,```,,,,`,,,``,``,-`-`,,`,,`,`,,`---(2)ThedisplayforTypeOOO-Sdurometersshallindicatefrom0to100withnolessthan100equaldivisionsthroughouttherangeatarateofonehardnesspointforeach0.050mm(0.002in.)ofindentormovement,(3)ThedisplayforTypeMdurometersshallindicatefrom0to100withnolessthan100equaldivisionsatarateofonehardnesspointforeach0.0125mm(0.0005in.)ofindentormovement,and(4)Inthecaseofanalogdialindicatorshavingadisplayof360°,thepointsindicating0and100maybeatthesamepointonthedialandindicate0,100,orboth.5.1.1.9TimingDevice(optional),capableofbeingsettoadesiredelapsedtime,signalingtheoperatororholdingthehardnessreadingwhenthedesiredelapsedtimehasbeenreached.Thetimershallbeautomaticallyactivatedwhenthepresserfootisincontactwiththespecimenbeingtested,forexample,theinitialindentortravelhasceased.Digitalelec-tronicdurometersmaybeequippedwithelectronictimingdevicesthatshallnotaffecttheindicatedreadingordetermi-nationsattainedbymorethanone-halfofthecalibrationtolerancestatedinTable1.5.1.1.10MaximumIndicators(optional),maximumindicat-ingpointersareauxiliaryanalogindicatinghandsdesignedtoremainatthemaximumhardnessvalueattaineduntilresetbyFIG.1(b)TypeBandDIndentor(continued)FIG.1(c)TypeO,DO,andOOIndentor(continued)FIG.1(d)TypeMIndentor(continued)D2240–05(2010)3theoperator.Electronicmaximumindicatorsaredigitaldis-playselectronicallyindicatingandmaintainingthemaximumvaluehardnessvaluedachieveduntilresetbytheoperator.5.1.1.11Analogmaximumindicatingpointershavebeenshowntohaveanominaleffectonthevaluesattained,however,thiseffectisgreaterondurometersoflessertotalmainspringloads;forexample,theeffectofamaximumindicatingpointeronTypeDdurometerdeterminationswillbelessthanthosedeterminationsachievedusingaTypeAdurometer.Analogstyledurometersmaybeequippedwithmaximumindicatingpointers.Theeffectofamaximumindicatingpointershallbenotedatthetimeofcalibrationinthecalibrationreport(see10.1.5),andwhenreportinghardnessdeterminations(see10.2.4).AnalogTypeM,OO,OOO,andTypeOOO-Sdurometersshallnotbeequippedwithmaximumindicatingpointers.5.1.1.12DigitalelectronicdurometersmaybeequippedwithelectronicmaximumindicatorsthatshallnotaffecttheindicatedreadingordeterminationsattainedbymorethanonehalfofthespringcalibrationtolerancestatedinTable1.5.1.1.13CalibratedSpring,forapplyingforcetotheinden-tor,inaccordancewithFig.1(athroughg)andcapableofapplyingtheforcesasspecifiedinTable1.5.1.2OperatingStand(Fig.2):5.1.2.1Type1,Type2,andType3shallbecapableofsupportingthedurometerpresserfootsurfaceparalleltothespecimensupporttable(Fig.3)throughoutthetravelofeach.Thedurometerpresserfoottospecimensupporttableparallel-ismshallbeverifiedeachtimethetestspecimensupporttableisadjustedtoaccommodatespecimensofvaryingdimensions.Thismaybeaccomplishedbyapplyingthedurometerpresserfoottothepointofcontactwiththespecimensupporttableandmakingadjustmentsbywayofthedurometermountingassem-blyorasspecifiedbythemanufacturer.5.1.2.2OperatingStand,Type1(specimentoindentortype),shallbecapableofapplyingthespecimentotheindentorinamannerthatminimizesshock.5.1.2.3OperatingStand,Type2(indentortospecimentype),shallbecapableofcontrollingtherateofdescentoftheindentortothespecimenatamaximumof3.20mm/s(0.125FIG.1(e)TypeOOOIndentor(continued)FIG.1(f)TypeOOO-SIndentor(continued)D2240–05(2010)4in./s)andapplyingaforcesufficienttoovercomethecalibratedspringforceasshowninTable1.5.1.2.4OperatingStand,Type3(indentortospecimentype),hydraulicdampening,pneumaticdampening,orelectro-mechanical(requiredfortheoperationofTypeMdurometers)shallbecapableofcontrollingtherateofdescentoftheindentortothespecimenatamaximumof3.2mm/s(0.125in./s)andapplyingaforcesufficienttoovercomethecalibratedspringforceasshowninTable1.Manualapplication,Type1orType2operatingstandsarenotacceptableforTypeMdurometeroperation.5.1.2.5Theentireinstrumentshouldbeplumbandlevel,andrestingonasurfacethatwillminimizevibration.Operatingtheinstrumentunderadverseconditionswillnegativelyaffectthedeterminationsattained.5.1.2.6SpecimenSupportTable,(Fig.3)integraltotheoperatingstand,andhavingasolidflatsurface.Thespecimensupportplatformmayhaveorificesdesignedtoacceptvariousinsertsorsupportfixtures(Fig.3)toprovideforthesupportofirregularlyconfiguredspecimens.Wheninsertsareusedtosupporttestspecimens,caremustbetakentoaligntheindentortothecenteroftheinsert,orthepointatwhichtheindentoristocontactthespecimen.Careshouldbeexercisedtoassurethattheindentordoesnotabruptlycontactthespecimensupporttableasdamagetotheindentormayresult.6.TestSpecimen6.1Thetestspecimen,hereinreferredtoas“specimen”or“testspecimen”interchangeably,shallbeatleast6.0mm(0.24in.)inthicknessunlessitisknownthatresultsequivalenttothe6.0-mm(0.24-in.)valuesareobtainedwithathinnerspecimen.6.1.1Aspecimenmaybecomposedofpliedpiecestoobtainthenecessarythickness,butdeterminationsmadeonsuchspecimensmaynotagreewiththosemadeonsolidspecimens,asthesurfacesofthepliedspecimensmaynotbeincompletecontact.Thelateraldimensionsofthespecimenshallbesufficienttopermitmeasurementsatleast12.0mm(0.48in.)fromanyedge,unlessitisknownthatidenticalresultsareobtainedwhenmeasurementsaremadeatalesserdistancefromanedge.6.1.2Thesurfacesofthespecimenshallbeflatandparalleloveranareatopermitthepresserfoottocontactthespecimenoveranareahavingaradiusofatleast6.0mm(0.24in.)fromtheindentorpoint.Thespecimenshallbesuitablysupportedtoprovideforpositioningandstability.AsuitablehardnessFIG.1(g)TypeEIndentor(continued)TABLE1DurometerSpringForceCalibrationAAllValuesareinNIndicatedValueTypeA,B,E,OTypeC,D,DOTypeMTypeOO,OOOTypeOOO-S00.5500.3240.2030.167101.34.4450.3680.2940.343202.058.890.4120.3850.520302.813.3350.4560.4760.696403.5517.780.50.5660.873504.322.2250.5440.6571.049605.0526.670.5890.7481.226705.831.1150.6330.8391.402806.5535.560.6770.931.579907.340.0050.7211.021.7551008.0544.450.7651.1111.932N/durometerunit0.0750.44450.00440.009080.01765SpringCalibrationTolerance60.075N60.4445N60.0176N60.0182N60.0353NAReferto5.1.1.3fortheTypexRdesignation.D2240–05(2010)5determinationcannotbemadeonanunevenorroughpointofcontactwiththeindentor.6.2TypeOOO,OOO-S,andMtestspecimensshouldbeatleast1.25mm(0.05in.)inthickness,unlessitisknownthatresultsequivalenttothe1.25-mm(0.05-in.)valuesareobtainedwithathinnerspecimen.6.2.1ATypeMspecimenthatisnotofaconfigurationdescribedin6.2.2maybecomposedofpliedpiecestoobtainFIG.2DurometerOperatingStandFIG.3SmallSpecimenSupportTableD2240–05(2010)6--``,,```,``,,```,,,,`,,,``,``,-`-`,,`,,`,`,,`---thenecessarythickness,butdeterminationsmadeonsuchspecimensmaynotagreewiththosemadeonsolidspecimensbecausethesurfacesofthepliedspecimensmaynotbeincompletecontact.Thelateraldimensionsofthespecimenshouldbesufficienttopermitmeasurementsatleast2.50mm(0.10in.)fromanyedgeunlessitisknownthatidenticalresultsareobtainedwhenmeasurementsaremadeatlesserdistancefromanedge.Asuitablehardnessdeterminationcannotbemadeonanunevenorroughpointofcontactwiththeindentor.6.2.2TheTypeMspecimen,whenconfiguredasano-ring,circularband,orotherirregularshapeshallbeatleast1.25mm(0.05in.)incross-sectionaldiameter,unlessitisknownthatresultsequivalenttothe1.25-mm(0.05-in.)valuesareobtainedwithathinnerspecimen.Thespecimenshallbesuitablysupportedinafixture(Fig.3)toprovideforpositioningandstability.6.3Theminimumrequirementforthethicknessofthespecimenisdependentontheextentofpenetrationoftheindentorintothespecimen;forexample,thinnerspecimensmaybeusedformaterialshavinghigherhardnessvalues.Theminimumdistancefromtheedgeatwhichmeasurementsmaybemadelikewisedecreasesasthehardnessincreases.7.Calibration7.1IndentorExtensionAdjustmentProcedure:7.1.1Placeprecisiongrounddimensionalblocks(GradeBorbetter)onthesupporttableandbeneaththedurometerpresserfootandindentor.Arrangetheblockssothatthedurometerpresserfootcontactsthelargerblock(s)andtheindentortipjustcontactsthesmallerblock(Fig.4).Itisnecessarytoobservethearrangementoftheblocksandthepresserfoot/indentorunderaminimumof203magnificationtoassureproperalignment.7.1.2Indentorextensionandshapeshallbeinaccordancewith5.1.1.5,5.1.1.6,or5.1.1.7,respectivetodurometertype.SeeFig.1(athroughg).Examinationoftheindentorunder203magnification,503forTypeMindentors,isrequiredtoexaminetheindentorcondition.Misshapenordamagedinden-torsshallbereplaced.7.1.3Acombinationofdimensionalgageblocksshallbeusedtoachieveadifferenceof2.54+0.00/–0.0254mm(0.100+0.00/–0.001in.)betweenthem.ForTypeOOO-Sdurometers,thegageblockdimensionsare5.08+0.00/–0.0508mm(0.200+0.00/–0.002in.).ForTypeMdurometers,thegageblockdimensionsare1.27+0.0/–0.0127mm(0.050+0.00/–0.0005in.)betweenthem(Fig.4).7.1.4Carefullylowerthedurometerpresserfootuntilitcontactsthelargestdimensionalblock(s),theindentortipshouldjustcontactthesmallerblock,verifyingfullindentorextension.7.1.5Adjusttheindentorextensionto2.5060.04mm(0.09860.002in.).ForTypeOOO-Sdurometers,adjusttheindentorextensionto5.060.04mm(0.19860.002in.).ForTypeMdurometers,adjusttheindentorextensionto1.2560.02mm(0.04960.001in.),followingthemanufacturer’srecommendedprocedure.7.1.5.1Whenperformingtheproceduresin7.1,careshouldbeusedsoasnottocausedamagetotheindentortip.Fig.4depictsasuitablearrangementforgagingindentorextension.7.1.6Parallelismofthedurometerpresserfoottothesupportsurface,andhencethedimensionalgageblocks,atthetimeofinstrumentcalibration,maybeinaccordancewithTestMethodsD374,Machinist’sMicrometers,orotherwiseaccom-plishedinaccordancewiththeproceduresspecifiedbythemanufacturer.7.2IndentorDisplayAdjustment:7.2.1Afteradjustingtheindentorextensionasindicatedin7.1,useasimilararrangementofdimensionalgageblockstoverifythelinearrelationshipbetweenindentortravelandindicateddisplayattwopoints:0and100.Followingthemanufacturer’srecommendations,makeadjustmentssothat:7.2.2Theindicatordisplaysavalueequaltotheindentortravelmeasuredtowithin:–0.0+1.0durometerunitsmeasuredat0;60.50durometerunitsmeasuredat100;61durometerunitsatallotherpointsdelineatedin7.4.7.2.3Eachdurometerpointindicatedisequalto0.025mm(0.001in.)ofindentortravel,exceptfor:7.2.3.1TypeMDurometers,eachindicatedpointisequalto0.0125mm(0.0005in.)ofindentortravel;7.2.3.2TypeOOO-SDurometers,eachindicatedpointisequalto0.050mm(0.002in.)ofindentortravel.7.2.4Theindicatorshallnotdisplayavaluegreaterthan100orlessthan0atthetimeofcalibration.7.2.5Othermeansofdeterminingindentorextensionorindentortravel,suchasopticalorlasermeasurementmethods,areacceptable.Theinstrumentationusedshallhavetraceabilityasdescribedin1.4.7.2.6Thedurometershallbesupportedinasuitablefashionwhenperformingtheproceduresdescribedin7.1and7.2.7.3CalibrationDevice:7.3.1Thedurometerspringshallbecalibratedbysupport-ingthedurometerinacalibratingdevice,seeFig.5,inaverticalpositionandapplyingameasurableforcetotheindentortip.TheforcemaybemeasuredbymeansofabalanceasdepictedinFig.5,oranelectronicforcecell.Thecalibratingdeviceshallbecapableofmeasuringappliedforcetowithin0.5%ofthemaximumspringforcenecessarytoachieve100durometerunits.7.3.2Careshouldbetakentoensurethattheforceisappliedverticallytotheindentortip,aslateralforcewillcauseerrorsincalibration.See7.1.5.1and7.1.6.FIG.4DetailofIndentorExtensionandDisplayAdjustmentD2240–05(2010)77.4SpringCalibration—Thedurometerspringshallbecalibratedatdisplayedreadingsof10,20,30,40,50,60,70,80,and90.Themeasuredforce(9.83massinkilograms)shallbewithinthespringcalibrationtolerancespecifiedinTable1.Table1identifiesthemeasuredforceappliedtotheindentorfortheentirerangeoftheinstrument,althoughitisnecessaryonlytoverifythespringcalibrationatpointslistedherein.7.5SpringCalibrationProcedure:7.5.1Ensurethattheindentorextensionhasbeenadjustedinaccordancewith7.1,andthelinearrelationshipbetweenindentortravelanddisplayisasspecifiedin7.2.7.5.2PlacethedurometerinthecalibrationdeviceasdepictedinFig.5.ApplytheforcesindicatedinTable1sothatforcesappliedarealignedwiththecenterlineoftheindentorinafashionthateliminatesshockorvibrationandadjustthedurometeraccordingtomanufacturers’recommendationssothat:7.5.3Atthepointsenumeratedin7.4,thedisplayshallindicateavalueequalto0.025mm(0.001in.)ofindentortravel.ForTypeOOO-Sdurometers,thedisplayshallindicateavalueequalto0.05mm(0.002in.)ofindentortravel.ForTypeMdurometers,thedisplayshallindicateavalueequalto0.0125mm(0.0005in.)ofindentortravelwithinthespringcalibrationtolerancesspecifiedin7.6.7.6Springcalibrationtolerancesare61.0durometerunitsforTypes