ASTM B692-18(2023)
(Specification)Standard Specification for 75 % Silver-25 % Graphite Sliding Contact Material
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.
General Information
- Status
- Published
- Publication Date
- 31-Mar-2023
- Technical Committee
- B02 - Nonferrous Metals and Alloys
Relations
- Effective Date
- 01-Jul-2018
- Effective Date
- 01-Jul-2017
- Effective Date
- 01-Dec-2012
- Effective Date
- 01-May-2012
- Effective Date
- 01-Nov-2011
- Effective Date
- 15-May-2008
- Effective Date
- 15-Jan-2008
- Effective Date
- 01-Apr-2007
- Effective Date
- 01-Jun-2006
- Effective Date
- 01-Apr-2005
- Effective Date
- 01-Feb-2005
- Effective Date
- 10-Jun-2003
- Effective Date
- 10-Jun-2003
- Effective Date
- 10-Jan-2002
- Effective Date
- 10-Jan-2002
Overview
ASTM B692-18(2023): Standard Specification for 75 % Silver-25 % Graphite Sliding Contact Material provides comprehensive criteria for the composition and physical properties of silver-graphite brushes used in sliding electrical contacts. Issued by ASTM International, this standard is essential for manufacturers and users to ensure the reliability, quality, and performance of electrical brushes composed of 75% silver and 25% graphite. The document addresses not only the chemical composition but also key aspects such as density, shear strength, microstructure, hardness, and specific resistance.
Key Topics
Chemical Composition
- Silver content: 75 ± 3% by weight
- Graphite: Remaining balance
- Total metal impurities: Maximum 1%
- Ash in graphite: No more than 5% as per NEMA CB-1
Physical Properties
- Density: Minimum 4.6 g/cm³, measured by the prescribed method
- Shear Strength:
- Normal/transverse directions: 2000 psi (14 MPa) minimum
- Longitudinal direction: 1000 psi (6.9 MPa) minimum
- Rockwell Hardness: Typical value is Rockwell 15W50 (measured by ASTM E18)
- Specific Resistance: Typical value is 6 × 10⁻⁶ Ω-in. (1.5 × 10⁻⁷ Ω-m) as per NEMA CB-1
Microstructure Requirements
- Visual inspection at 50× magnification to ensure absence of defects such as cracks or abrasive particles
- Structural integrity aligned with the ordered specifications
Manufacturing Controls and Certification
- Notification required for changes in raw materials or manufacturing processes
- Mandatory certification by the material producer to confirm compliance with all standard requirements
Safety and Compliance
- Users are responsible for safety, health, and environmental considerations, referencing manufacturer Safety Data Sheets (SDS)
- Developed in line with World Trade Organization (WTO) principles for international standards
Applications
ASTM B692-18(2023) is widely utilized in industries where sliding electrical contacts are critical, such as:
- Electrical machinery: Ensures high conductivity and durability in components like electrical brushes for motors, generators, and alternators.
- Railway and transit systems: Used in current collection equipment and sliding contacts, offering stable performance under various load conditions.
- Energy and power generation: Reliable electrical contact materials are vital in turbines, switchgear, and rotating apparatus.
- Aerospace and defense: Components requiring robust conductivity and wear resistance benefit from this standardized composition.
- Industrial equipment: Robotics, automated systems, and heavy machinery often employ silver-graphite brushes for their unique electrical and physical properties.
By adhering to this specification, manufacturers and engineers can achieve consistent product quality, reduced downtime, and enhanced operational life for sliding contact assemblies.
Related Standards
For expanded guidance and best practices, refer to these related standards:
- ASTM B613: Guide for Preparing Specifications for Miniature Brushes of Composite Materials for Sliding Electric Contacts
- ASTM E18: Test Methods for Rockwell Hardness of Metallic Materials
- NEMA CB-1: Brushes for Electrical Machines - Defines measurement methods referenced in this specification
These documents complement ASTM B692-18(2023) to further ensure that silver-graphite sliding contact materials meet rigorous performance and safety demands in a wide variety of electrical and mechanical applications.
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Frequently Asked Questions
ASTM B692-18(2023) is a technical specification published by ASTM International. Its full title is "Standard Specification for 75 % Silver-25 % Graphite Sliding Contact Material". This standard covers: 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.
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.
ASTM B692-18(2023) is classified under the following ICS (International Classification for Standards) categories: 77.120.99 - Other non-ferrous metals and their alloys. The ICS classification helps identify the subject area and facilitates finding related standards.
ASTM B692-18(2023) has the following relationships with other standards: It is inter standard links to ASTM E18-18, ASTM E18-17, ASTM E18-12, ASTM B613-76(2012), ASTM E18-11, ASTM E18-08a, ASTM E18-08, ASTM E18-07, ASTM B613-76(2006), ASTM E18-05e1, ASTM E18-05, ASTM E18-03e1, ASTM E18-03, ASTM E18-00, ASTM E18-02. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
ASTM B692-18(2023) is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
Standards Content (Sample)
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.
Designation: B692 − 18 (Reapproved 2023)
Standard Specification for
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:
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
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
Development of International Standards, Guides and Recom-
(6.9 MPa), minimum.
mendations issued by the World Trade Organization Technical
3.3 Microstructure—Parts shall be visually free of structural
Barriers to Trade (TBT) Committee.
defects, cracks, etc., upon examination at 50×. The press
2. Referenced Documents direction, as evidenced by laminations, shall be as defined by
the purchase order. Also the brush material shall not contain
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
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× t
...
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