Designation:B702−93(Reapproved2015)StandardSpecificationforCopper-TungstenElectricalContactMaterial1ThisstandardisissuedunderthefixeddesignationB702;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thisspecificationcoverselectricalcontactcomponentsmadefromcoppertungstenbypowdermetallurgicalproce-dures.1.2Thisspecificationcoverscompositionswithinthecop-pertungstensystemnormallyspecifiedbyusersofcontacts.1.3Thevaluesstatedininch-poundunitsaretoberegardedasstandard.Nootherunitsofmeasurementareincludedinthisstandard.1.4Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.ItistheresponsibilityoftheuserofthisstandardtobecomefamiliarwithallhazardsincludingthoseidentifiedintheappropriateDataSafetySheet(SDS)forthisproduct/materialasprovidedbythemanufacturer,toestablishappropriatesafetyandhealthpractices,anddeterminetheapplicabilityofregulatorylimi-tationspriortouse.2.ReferencedDocuments2.1ASTMStandards:2B328TestMethodforDensity,OilContent,andIntercon-nectedPorosityofSinteredMetalStructuralPartsandOil-ImpregnatedBearings(Withdrawn2009)33.SignificanceandUse3.1Proprietarymethodsformanufactureofthesematerialsvarysignificantlyamongsuppliersandthesemethodsinfluencesuchpropertiesasarcerosion,contactresistance,andtendencytoweldinservice.Sincetheperformanceofcontactsinadevicedependsonnumerousfactorsoutsidethecontactitself(openingspeed,closingspeed,contactpressure,contactbounce,environmentalvariations,assemblytechniqueandvariations,etc.)thisspecificationcannotensureperformancecontrolintheapplication.Aspartofthequalificationoninitialsamplesitisrecommendedthattheuserfunctionallyelectri-callytestthematerialsforalldevicesapplicabletothematerial’suse.Thisspecificationwillprovideameansforthecontactmanufacturerandcontactusertoreachagreemento...
