ASTM B702-93(1998)
(Specification)Standard Specification for Copper-Tungsten Electrical Contact Material
Standard Specification for Copper-Tungsten Electrical Contact Material
SCOPE
1.1 This specification covers electrical contact components made from copper tungsten by powder metallurgical procedures.
1.2 This specification covers compositions within the copper tungsten system normally specified by users of contacts.
1.3 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
1.4 It is the responsibility of the user to become familiar with all hazards including those identified in the appropriate Material Safety Data Sheet for this product/material as provided by the manufacturer.
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: B 702 – 93 (Reapproved 1998)
Standard Specification for
Copper-Tungsten Electrical Contact Material
This standard is issued under the fixed designation B 702; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope reasonable assurance that future lots will be similar in proper-
ties and microstructure to the initial test or sample contacts
1.1 This specification covers electrical contact components
supplied.
made from copper tungsten by powder metallurgical proce-
dures.
4. Ordering Information
1.2 This specification covers compositions within the cop-
4.1 Orders for this material under this specification shall
per tungsten system normally specified by users of contacts.
include the following information:
1.3 This standard does not purport to address all of the
4.1.1 Dimensions (see Section 8),
safety concerns, if any, associated with its use. It is the
4.1.2 Chemical composition (see reference tables in Related
responsibility of the user of this standard to establish appro-
Material as possible guideline),
priate safety and health practices and determine the applica-
4.1.3 Physical properties (see Section 6 and reference tables
bility of regulatory limitations prior to use.
as guideline),
1.4 It is the responsibility of the user to become familiar
4.1.4 Certification (see Section 11), and
with all hazards including those identified in the appropriate
4.1.5 Other features as agreed upon between the vendor and
Material Safety Data Sheet for this product/material as pro-
the user.
vided by the manufacturer.
5. Chemical Requirements
2. Referenced Documents
5.1 The material shall conform to composition limits as
2.1 ASTM Standards:
agreed upon between the manufacturer and the user.
B 328 Test Method for Density, Oil Content, and Intercon-
5.2 The chemical analysis shall be made in accordance with
nected Porosity of Sintered Metal Structural Parts and
the methods prescribed in the newest edition of Annual Book of
Oil-Impregnated Bearings
ASTM Standards, or by any other approved method agreed
3. Significance and Use upon between the manufacturer and the purchaser.
3.1 Proprietary methods for manufacture of these materials
6. Other Properties
vary significantly among suppliers and these methods influence
6.1 The manufacturer and the purchaser shall agree on
such properties as arc erosion, contact resistance, and tendency
qualification tests for determination of physical properties.
to weld in service. Since the performance of contacts in a
6.2 The tests shall be performed on production parts,
device depends on numerous factors outside the contact itself
wherever practical or applicable. (Small size contacts do not
(opening speed, closing speed, contact pressure, contact
lend themselves to accurate conductivity measurement.)
bounce, environmental variations, assembly technique and
6.3 The tests shall be determined after consideration of the
variations, etc.) this specification cannot ensure performance
function of the part.
control in the application. As part of the qualification on initial
6.4 The typical properties of five most common types of
samples it is recommended that the user functionally electri-
copper-tungsten contacts are given in Appendix X1.
cally test the materials for all devices applicable to the
material’s use. This specification will provide a means for the
7. Dimensions and Permissible Variations
contact manufacturer and contact user to reach agreement on
7.1 Permissible variations in dimensions shall be within the
the details of material to be supplied for a specified use and
limits specified on drawings describing the contacts and
accompanying the order, or shall be within the limits specified
This specification is under the jurisdiction of ASTM Committee B-2 on in the purchase order.
Nonferrous Metals and Alloys and is the direct responsibility of Subcommittee
B2.05 on Precious Metals.
8. Workmanship, Finish, and Appearance
Current edition approved Aug. 15, 1993. Published October 1993. Originally
8.1 The parts shall be free of defects in material or process-
published as B 702 – 82. Last previous edition B 702 – 88.
Annual Book of ASTM Standards, Vol 02.05. ing, which would seriously affect their performance.
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B 702 – 93 (1998)
9. Sampling and Inspection 9.3 Physical Tests—The manufacturer and the purchaser
shall agree on a representative number of specimens for
9.1 Lot—Unless otherwise specified, a lot shall consist of
physical tests including microstructure.
parts of the same form, and dimensions, made of powders of
the same particle size range and composition, processed under
10. Rejection and Rehearing
the same conditions, and submitted for inspection at one time.
9.2 Chemical Analysis—At least one sample for chemical
10.1 Unless otherwise specified, rejections based on tests
analysis shall be taken from each lot. A representative sample
made in accordance with the specification shall be reported to
of chips may be obtained by milling, drilling, or crushing at
the manufacturer within 30 days
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