ASTM_B_692_-_90_2012.pdf

Designation:B69290(Reapproved 2012)Standard Specification for75%Silver-25%Graphite Sliding Contact Material1This standard is issued under the fixed designation B692;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This specification defines the criteria for compositionand other requirements for brushes with a nominal silvercontent of 75 weight%with the balance being substantiallygraphite.1.2 The values stated in inch-pound units are to be regardedas standard.The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.3 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to become familiarwith all hazards including those identified in the appropriateMaterial Safety Data Sheet(MSDS)for this product/materialas provided by the manufacturer,to establish appropriatesafety and health practices,and determine the applicability ofregulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2B613 Guide for Preparing Specifications for MiniatureBrushes of Composite Materials for Sliding ElectricContactsE18 Test Methods for Rockwell Hardness of Metallic Ma-terials2.2 ANSI Standard:C64.1 Brushes for Electrical Machines33.Requirements3.1 Chemical Composition shall be as follows:Silver75 3%(weight)GraphitebalanceTotal metal impurities1%maxPercent ash in graphite(ANSI C64.1)5%max3.2 Physical PropertiesThe following lot average proper-ties must be met.Unless otherwise agreed between the pro-ducer and the user,the number of samples shall be five.3.2.1 DensityThe minimum acceptable density shall be4.6 g/cm3as determined by the measurement and weightmethod defined by ANSI C64.1.3.2.2 Shear Strength:3.2.2.1 The shear strength for the normal and transversedirections shall be measured for rectangular parallelepipedsand shall be 2000 psi(14 MPa),minimum.3.2.2.2 The shear strength for the longitudinal shear direc-tion shall be measured for cylinders and shall be 1000 psi(6.9MPa),minimum.3.3 MicrostructureParts shall be visually free of structuraldefects,cracks,etc.,upon examination at 50.The pressdirection,as evidenced by laminations,shall be as defined bythe purchase order.Also the brush material shall not containabrasive particles that will sliver a metal-alloy ring with ahardness$110 HK100when the brush force is equal to 30 g orthat necessary for 5.0 psi(34 kPa)pressure,whichever isgreater.A sliver is defined as a loose wear particle with onedimension$50 the next smaller dimension.Although sliver-ing can be caused by coarse abrasive particles,other param-eters can contribute to slivering(for example,very high brushforce).3.4 Source or Grade of Raw Materials(for example,graph-ite)or methods of manufacture shall not be changed withoutnotifying users.4.Reference Properties4.1 Because of their size,the following properties can notalways be determined.However,these properties are typicalfor larger parts.1This specification is under the jurisdiction of ASTM Committee B02 onNonferrous Metals and Alloys and is the direct responsibility of SubcommitteeB02.05 on Precious Metals and Electrical Contact Materials.Current edition approved May 1,2012.Published May 2012.Originallyapproved in 1981.Last previous edition approved in 2006 as B692 90(2006).DOI:10.1520/B0692-90R12.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3Available from Standardization Documents Order Desk,DODSSP,Bldg.4,SectionD,700RobbinsAve.,Philadelphia,PA19111-5098,http:/dodssp.daps.dla.mil.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 4.1.1 Superficial HardnessThe typical superficial hard-ness for this material is Rockwell 15W50 as determined byTest Methods E18 with a18-in.(3.2-mm)steel ball.4.1.2 Specific ResistanceThe typical specific resistancefor the material is 6 106V-in.(1.5 107V-m)asdetermined by the method detailed in ANSI C64.1.5.Certification5.1 Material supplied under this specification shall be cer-tified as meeting the requirements of this specification by theproducer of the material.6.Keywords6.1 electrical contacts;graphite;silver;sliding contactsASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard.Users of this standard are expressly advised that determination of the validity of any such patent rights,and the riskof infringement of such rights,are entirely their own responsib