Standard Specification for 75 % Silver-25 % Graphite Sliding Contact Material

ABSTRACT
This specification defines the criteria for the chemical composition and other requirements (including physical properties, microstructure, superficial hardness, and specific resistance ) for silver-graphite brushes for sliding electrical contacts. The percentage of silver, graphite, ash in graphite, and total metal impurities are prescribed. The minimum acceptable values for the physical properties such as density, determined by measurement and weight method, and shear strength are given. Typical Rockwell hardness and specific resistance for the material are also specified.
SCOPE
1.1 This specification defines the criteria for composition and other requirements for brushes with a nominal silver content of 75 weight % with the balance being substantially graphite.  
1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.  
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to become familiar with all hazards including those identified in the appropriate Safety Data Sheet (SDS) for this product/material as provided by the manufacturer, to establish appropriate safety, health, and environmental practices, and determine the applicability of regulatory limitations prior to use.  
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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Historical
Publication Date
31-Oct-2018
Current Stage
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ASTM B692-18 - Standard Specification for 75 % Silver-25 % Graphite Sliding Contact Material
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Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: B692 − 18
Standard Specification for
1
75 % Silver-25 % Graphite Sliding Contact Material
This standard is issued under the fixed designation B692; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2.2 NEMA Standard:
3
CB-1 Brushes for Electrical Machines
1.1 This specification defines the criteria for composition
and other requirements for brushes with a nominal silver
3. Requirements
content of 75 weight % with the balance being substantially
graphite. 3.1 Chemical Composition shall be as follows:
Silver 75 ± 3 % (weight)
1.2 The values stated in inch-pound units are to be regarded
Graphite balance
as standard. The values given in parentheses are mathematical
Total metal impurities 1 % max
Percent ash in graphite (NEMA CB-1) 5 % max
conversions to SI units that are provided for information only
and are not considered standard.
3.2 Physical Properties—The following lot average proper-
ties must be met. Unless otherwise agreed between the pro-
1.3 This standard does not purport to address all of the
ducer and the user, the number of samples shall be five.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to become familiar 3.2.1 Density—The minimum acceptable density shall be
3
with all hazards including those identified in the appropriate 4.6 g/cm as determined by the measurement and weight
Safety Data Sheet (SDS) for this product/material as provided method defined by NEMA CB-1.
by the manufacturer, to establish appropriate safety, health,
3.2.2 Shear Strength:
and environmental practices, and determine the applicability
3.2.2.1 The shear strength for the normal and transverse
of regulatory limitations prior to use.
directions shall be measured for rectangular parallelepipeds
1.4 This international standard was developed in accor-
and shall be 2000 psi (14 MPa), minimum.
dance with internationally recognized principles on standard-
3.2.2.2 The shear strength for the longitudinal shear direc-
ization established in the Decision on Principles for the
tion shall be measured for cylinders and shall be 1000 psi (6.9
Development of International Standards, Guides and Recom-
MPa), minimum.
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee. 3.3 Microstructure—Parts shall be visually free of structural
defects, cracks, etc., upon examination at 50×. The press
direction, as evidenced by laminations, shall be as defined by
2. Referenced Documents
the purchase order. Also the brush material shall not contain
2
2.1 ASTM Standards:
abrasive particles that will sliver a metal-alloy ring with a
B613 Guide for Preparing Specifications for Miniature
hardness ≥110 HK when the brush force is equal to 30 g or
100
Brushes of Composite Materials for Sliding Electric
that necessary for 5.0 psi (34 kPa) pressure, whichever is
Contacts
greater. A sliver is defined as a loose wear particle with one
E18 Test Methods for Rockwell Hardness of Metallic Ma-
dimension ≥50× the next smaller dimension. Although sliver-
terials
ing can be caused by coarse
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: B692 − 90 (Reapproved 2012) B692 − 18
Standard Specification for
1
75 % Silver-25 % Graphite Sliding Contact Material
This standard is issued under the fixed designation B692; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This specification defines the criteria for composition and other requirements for brushes with a nominal silver content of
75 weight % with the balance being substantially graphite.
1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical
conversions to SI units that are provided for information only and are not considered standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to become familiar with all hazards including those identified in the appropriate Material Safety Data
Sheet (MSDS)(SDS) for this product/material as provided by the manufacturer, to establish appropriate safety safety, health, and
healthenvironmental practices, and determine the applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2
2.1 ASTM Standards:
B613 Guide for Preparing Specifications for Miniature Brushes of Composite Materials for Sliding Electric Contacts
E18 Test Methods for Rockwell Hardness of Metallic Materials
2.2 ANSINEMA Standard:
3
C64.1CB-1 Brushes for Electrical Machines
3. Requirements
3.1 Chemical Composition shall be as follows:
Silver 75 ± 3 % (weight)
Graphite balance
Total metal impurities 1 % max
Percent ash in graphite (ANSI C64.1) 5 % max
Percent ash in graphite (NEMA CB-1) 5 % max
3.2 Physical Properties—The following lot average properties must be met. Unless otherwise agreed between the producer and
the user, the number of samples shall be five.
3
3.2.1 Density—The minimum acceptable density shall be 4.6 g/cm as determined by the measurement and weight method
defined by ANSI C64.1.NEMA CB-1.
3.2.2 Shear Strength:
3.2.2.1 The shear strength for the normal and transverse directions shall be measured for rectangular parallelepipeds and shall
be 2000 psi (14 MPa), minimum.
3.2.2.2 The shear strength for the longitudinal shear direction shall be measured for cylinders and shall be 1000 psi (6.9 MPa),
minimum.
1
This specification is under the jurisdiction of ASTM Committee B02 on Nonferrous Metals and Alloys and is the direct responsibility of Subcommittee B02.05 on
Precious Metals and Electrical Contact Materials.
Current edition approved May 1, 2012Nov. 1, 2018. Published May 2012January 2019. Originally approved in 1981. Last previous edition approved in 20062012 as
B692 – 90 (2006).(2012). DOI: 10.1520/B0692-90R12.10.1520/B0692-18.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’sstandard’s Document Summary page on the ASTM website.
3
Available from Standardization Documents Order Desk, DODSSP, Bldg. 4, Section D, 700 Robbins Ave., Philadelphia, PA 19111-5098, http://
dodssp.daps.dla.mil.National Electrical Manufacturers Association (NEMA), 1300 N. 17th St., Suite 1752, Rosslyn, VA 22209, http://www.nema.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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B692 − 18
3.3 Microstructure—Parts shall be visually free of structural defects, cracks, etc., upon examination at 50×. The press direction,
as evidenced by laminations, shall be as defined by the purchase order. Also the brush material shall not contain abrasive particles
that will sliver a metal-alloy ring with a hardness ≥110 HK when the brush force is equal to 30 g or that necessary for 5.0 psi
100
(34 kPa) pressure, whichever is greater. A sliver is defined as a loose wear particle with one dimension ≥50× the next smaller
dimension.
...

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