ASTM B702-93(2010)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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:B702 −93(Reapproved 2010)
Standard Specification for
Copper-Tungsten Electrical Contact Material
This standard is issued under the fixed designation B702; 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 bounce, environmental variations, assembly technique and
variations, etc.) this specification cannot ensure performance
1.1 This specification covers electrical contact components
control in the application.As part of the qualification on initial
made from copper tungsten by powder metallurgical proce-
samples it is recommended that the user functionally electri-
dures.
cally test the materials for all devices applicable to the
1.2 This specification covers compositions within the cop-
material’s use. This specification will provide a means for the
per tungsten system normally specified by users of contacts.
contact manufacturer and contact user to reach agreement on
the details of material to be supplied for a specified use and
1.3 The values stated in inch-pound units are to be regarded
as standard. No other units of measurement are included in this reasonable assurance that future lots will be similar in proper-
ties and microstructure to the initial test or sample contacts
standard.
supplied.
1.4 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
4. Ordering Information
responsibility of the user of this standard to become familiar
with all hazards including those identified in the appropriate 4.1 Orders for this material under this specification shall
Material Data Safety Sheet (MSDS) for this product/material include the following information:
as provided by the manufacturer, to establish appropriate 4.1.1 Dimensions (see Section 8),
safety and health practices, and determine the applicability of 4.1.2 Chemical composition (see reference tables in Related
regulatory limitations prior to use. Material as possible guideline),
4.1.3 Physical properties (see Section 6 and reference tables
2. Referenced Documents
as guideline),
4.1.4 Certification (see Section 11), and
2.1 ASTM Standards:
4.1.5 Other features as agreed upon between the vendor and
B328 Test Method for Density, Oil Content, and Intercon-
the user.
nected Porosity of Sintered Metal Structural Parts and
Oil-Impregnated Bearings (Withdrawn 2009)
5. Chemical Requirements
3. Significance and Use
5.1 The material shall conform to composition limits as
agreed upon between the manufacturer and the user.
3.1 Proprietary methods for manufacture of these materials
varysignificantlyamongsuppliersandthesemethodsinfluence
5.2 The chemical analysis shall be made in accordance with
such properties as arc erosion, contact resistance, and tendency
the methods prescribed in the newest edition of Annual Book of
to weld in service. Since the performance of contacts in a
ASTM Standards, or by any other approved method agreed
device depends on numerous factors outside the contact itself
upon between the manufacturer and the purchaser.
(opening speed, closing speed, contact pressure, contact
6. Other Properties
6.1 The manufacturer and the purchaser shall agree on
This specification is under the jurisdiction of ASTM Committee B02 on
qualification tests for determination of physical properties.
Nonferrous Metals and Alloys and is the direct responsibility of Subcommittee
B02.05 on Precious Metals and Electrical Contact Materials.
6.2 The tests shall be performed on production parts,
Current edition approved Oct. 1, 2010. Published October 2010. Originally
wherever practical or applicable. (Small size contacts do not
approved in 1982. Last previous edition approved in 2004 as B702 – 93 (2004).
DOI: 10.1520/B0702-93R10. lend themselves to accurate conductivity measurement.)
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
6.3 The tests shall be determined after consideration of the
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on function of the part.
the ASTM website.
6.4 The typical properties of five most common types of
The last approved version of this historical standard is referenced on
www.astm.org. copper-tungsten contacts are given in Appendix X1.
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B702−93 (2010)
7. Dimensions and Permissible Variations listed in the table. However, if a user knows of elements that
might be detrimental to their application or has other reasons
7.1 Permissible variations in dimensions shall be within the
for requiring analysis for specific elements, then agreement
limits specified on drawings describing the contacts and
between manufacturer and purchaser for both limits and
accompanying the order, or shall be within the limits specified
methods of analysis should be required for elements not
in the purchase order.
specified.
8. Workmanship, Finish, and Appearance
9.3 Physical Tests—The manufacturer and the purchaser
8.1 The parts shall be free of defects in material or shall agree on a representative number of specimens for
physical tests including microstructure.
processing, which would seriously affect their performance.
9. Sampling and Inspection
10. Rejection and Rehearing
9.1 Lot—Unless otherwise specified, a lot shall consist of 10.1 Unless
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