ASTM B702-93(2004)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: B702 – 93 (Reapproved 2004)
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 control in the application.As part of the qualification on initial
samples it is recommended that the user functionally electri-
1.1 This specification covers electrical contact components
cally test the materials for all devices applicable to the
made from copper tungsten by powder metallurgical proce-
material’s use. This specification will provide a means for the
dures.
contact manufacturer and contact user to reach agreement on
1.2 This specification covers compositions within the cop-
the details of material to be supplied for a specified use and
per tungsten system normally specified by users of contacts.
reasonable assurance that future lots will be similar in proper-
1.3 This standard does not purport to address all of the
ties and microstructure to the initial test or sample contacts
safety concerns, if any, associated with its use. It is the
supplied.
responsibility of the user of this standard to become familiar
with all hazards including those identified in the appropriate
4. Ordering Information
Material Data Safety Sheet for this product/material as pro-
4.1 Orders for this material under this specification shall
vided by the manufacturer, to establish appropriate safety and
include the following information:
health practices, and determine the applicability of regulatory
4.1.1 Dimensions (see Section 8),
limitations prior to use.
4.1.2 Chemical composition (see reference tables in Related
2. Referenced Documents Material as possible guideline),
4.1.3 Physical properties (see Section 6 and reference tables
2.1 ASTM Standards:
as guideline),
B328 Test Method for Density, Oil Content, and Intercon-
4.1.4 Certification (see Section 11), and
nected Porosity of Sintered Metal Structural Parts and
4.1.5 Other features as agreed upon between the vendor and
Oil-Impregnated Bearings
the user.
3. Significance and Use
5. Chemical Requirements
3.1 Proprietary methods for manufacture of these materials
5.1 The material shall conform to composition limits as
varysignificantlyamongsuppliersandthesemethodsinfluence
agreed upon between the manufacturer and the user.
such properties as arc erosion, contact resistance, and tendency
5.2 The chemical analysis shall be made in accordance with
to weld in service. Since the performance of contacts in a
themethodsprescribedinthenewesteditionof Annual Book of
device depends on numerous factors outside the contact itself
ASTM Standards, or by any other approved method agreed
(opening speed, closing speed, contact pressure, contact
upon between the manufacturer and the purchaser.
bounce, environmental variations, assembly technique and
variations, etc.) this specification cannot ensure performance
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
6.2 The tests shall be performed on production parts,
B02.05 on Precious Metals and Electrical Contact Materials.
wherever practical or applicable. (Small size contacts do not
Current edition approved May 1, 2004. Published May 2004. Originally
approved in 1982. Last previous edition approved in 1993 as B702 – 93 (1998). lend themselves to accurate conductivity measurement.)
DOI: 10.1520/B0702-93R04.
6.3 The tests shall be determined after consideration of the
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
function of the part.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
6.4 The typical properties of five most common types of
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
copper-tungsten contacts are given in Appendix X1.
Withdrawn. The last approved version of this historical standard is referenced
on www.astm.org.
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B702 – 93 (2004)
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.
9.3 Physical Tests—The manufacturer and the purchaser
8. Workmanship, Finish, and Appearance
shall agree on a representative number of specimens for
8.1 The parts shall be free of defects in material or process-
physical tests including microstructure.
ing, which would seriously affect their performance.
10. Rejection and Rehearing
9. Sampling and Inspection
10.1 Unless otherwise specified, rejections based on tests
9.1 Lot—Unless otherwise specified, a
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