ASTM B896-10(2020)
(Test Method)Standard Test Methods for Evaluating Connectability Characteristics of Electrical Conductor Materials
Standard Test Methods for Evaluating Connectability Characteristics of Electrical Conductor Materials
SIGNIFICANCE AND USE
5.1 These test methods develop comparative information useful for the design of stationary contacts for wire, cable, and other conductors.
5.2 These test methods produce results, which are free of the influence of arbitrary connection systems.
5.3 The influence of conductor surface pretreatments and platings can be evaluated by these test methods.
5.4 The influence of environmental factors, such as high temperature and corrosive environment can be evaluated by these test methods.
5.5 The results obtained by these test methods provide guidance on connection system design parameters, such as contact force and gas tightness requirements.
SCOPE
1.1 These test methods define procedures for the relative characterization of conductor material connectability on the basis of measurements of parameters important to the design and performance of electrical contacts and connections to and with such conductors for both power and signal applications.
1.2 The parameters measured are contact resistance as a function of contact force, fretting sensitivity, and compressive relaxation.
1.3 Provision is made for measurement of the connectability parameters at elevated temperature, or corrosive ambient, or both, as may be required for evaluation for particular applications.
1.4 These test methods, using standardized specimen geometry and procedures, are applicable to conductor materials as employed in an electrical system and may be adapted for evaluation of connectability of materials in the form of actual connection system components.
1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.6 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.
1.7 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
Relations
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: B896 − 10 (Reapproved 2020)
Standard Test Methods for
Evaluating Connectability Characteristics of Electrical
Conductor Materials
This standard is issued under the fixed designation B896; 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. Referenced Documents
1.1 These test methods define procedures for the relative 2.1 ASTM Standards:
characterization of conductor material connectability on the B539 Test Methods for Measuring Resistance of Electrical
basis of measurements of parameters important to the design Connections (Static Contacts)
and performance of electrical contacts and connections to and B542 Terminology Relating to Electrical Contacts and Their
with such conductors for both power and signal applications. Use
1.2 The parameters measured are contact resistance as a
3. Terminology
function of contact force, fretting sensitivity, and compressive
3.1 Definitions—Definitions of terms used in this test
relaxation.
method are in accordance with Terminology B542.
1.3 Provision is made for measurement of the connectability
3.2 Definitions of Terms Specific to This Standard:
parameters at elevated temperature, or corrosive ambient, or
3.2.1 connectability, n—a combination of properties deter-
both, as may be required for evaluation for particular applica-
mining the ability of a material to establish and maintain stable
tions.
low resistance electrical contact under the influence of dete-
1.4 These test methods, using standardized specimen geom-
riorating environmental and operational factors.
etry and procedures, are applicable to conductor materials as
3.2.2 fretting, n—accelerated surface damage occurring at
employed in an electrical system and may be adapted for
the interface of contacting materials subjected to small oscil-
evaluation of connectability of materials in the form of actual
latory displacements.
connection system components.
4. Summary of Test Method
1.5 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this
4.1 Contact Resistance—Contact resistance is measured as
standard.
force is increased between conductors in a crossed-rod contact
pair of the material(s) being tested. Held at the maximum
1.6 This standard does not purport to address all of the
specified force, test contacts may be exposed to temperature
safety concerns, if any, associated with its use. It is the
changes or corrosive environments such as high humidity to
responsibility of the user of this standard to become familiar
observe the effects of such conditions on electrical contact
with all hazards including those identified in the appropriate
resistance.
Safety Data Sheet (SDS) for this product/material as provided
by the manufacturer, to establish appropriate safety, health,
4.2 Fretting Sensitivity—Contact resistance of a crossed-rod
and environmental practices, and determine the applicability
pair is measured at constant normal force while a microscopic
of regulatory limitations prior to use.
oscillitory tangential motion is applied at the contact interface.
1.7 This international standard was developed in accor-
The number of applied motion cycles required to induce
dance with internationally recognized principles on standard-
contact resistance instability is determined. The test may be
ization established in the Decision on Principles for the
performed at elevated temperature or in corrosive environment.
Development of International Standards, Guides and Recom-
4.3 Compressive Relaxation—Change of applied contact
mendations issued by the World Trade Organization Technical
force with time, at fixed engagement displacement of crossed-
Barriers to Trade (TBT) Committee.
wire specimens, is measured. The test may be performed at
elevated temperature.
These test methods are under the jurisdiction of ASTM Committee B02 on
Nonferrous Metals and Alloys and are the direct responsibility of Subcommittee
B02.05 on Precious Metals and Electrical Contact Materials and Test Methods. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Oct. 1, 2020. Published October 2020. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1999. Last previous edition approved in 2015 as B896 – 10 (2015). Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/B0896-10R20. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
B896 − 10 (2020)
5. Significance and Use 6.3.5 Instrumentation is provided for measurement of con-
tact force, contact current, and contact voltage. The maximum
5.1 These test methods develop comparative information
open circuit voltage shall be 10 mV and the maximum current
useful for the design of stationary contacts for wire, cable, and
shall be 100 mA.
other conductors.
6.3.6 Constant load long-term testing at the maximum force
5.2 These test methods produce results, which are free of the
(see 6.3.3) the specimen assembly may be fixed, maintaining
influence of arbitrary connection systems.
the contact force and the physical relationship between the
specimens so as to allow controlled evaluation of the effects of
5.3 The influence of conductor surface pretreatments and
platings can be evaluated by these test methods. long-term environmental variables, such as temperature,
humidity, or gaseous ambient.
5.4 The influence of environmental factors, such as high
6.3.7 Constant displacement long-term testing at the maxi-
temperature and corrosive environment can be evaluated by
mum force (see 6.3.4), the specimen assembly may be fixed,
these test methods.
maintaining the contact displacement and the physical relation-
5.5 The results obtained by these test methods provide
ship between the specimens so as to allow controlled evalua-
guidance on connection system design parameters, such as
tion of the effects of long-term environmental variables, such
contact force and gas tightness requirements.
as temperature, humidity, or gaseous ambient under conditions
whereby the contact load is influenced by stress-relaxation
6. Test Methods
effects. Fixture design for constant displacement testing must
be rigid and matched in thermal expansion characteristics to
6.1 These test methods provide for standardization of speci-
the material being tested, such as to maintain displacement
men geometry, contact loads, and other factors, which may
within 1 % of the initial value for the temperature range in
influence the results. Use of nonstandard specimens or proce-
which it is used for the duration of the test. The rigidity
dures may influence the validity of relative connectability
requirement may be satisfied by a fixture whose spring constant
comparisons based on the test results.
(force/unit displacement) is calculated to be no less than 200×
CROSSED WIRE CONTACT RESISTANCE—FIXED
larger than the elastic spring constant of the specimen pair
LOAD
when fully engaged. The specimen spring constant is deter-
mined by measuring the displacement required to decrease the
6.2 The standard specimen shall be 2 mm (#12 AWG)
contact force to 1 kg from an initial 2 kg.
diameter wire, at least 25 mm long, and straight to within 1 %.
6.3.8 For the purpose of environmental exposure in accor-
Specimens of nonstandard diameter may be used. Resulting
dance with 6.3.6 and 6.3.7, the fixturing shall be designed to
performance data only is considered valid for comparison with
maintain contact load within 62 % over the range of applied
results on same-size specimens, however.
temperature for the duration of the test. Fixturing shall be
6.3 The apparatus consists of a fixture capable of perform-
designed symmetrically so as to preclude introduction of shear
ing as follows:
forces in the plane of the specimen contact interface as
6.3.1 Specimens are oriented perpendicular to one another.
temperature is changed.
Contact between the specimens occurs approximately at the
6.3.9 The specific design of the apparatus may vary, pro-
center of each specimen (lengthwise).
vided that the functional requirements are met. A representative
6.3.2 Specimens are supported by flat or vee-groove, or
embodiment of a constant load crossed-wire fixture is provided
equivalent holders, so as to prevent bending due to applied
in Appendix X1. For constant displacement crossed-wire
contact load. Specimen support fixture shall support the speci-
testing, a variation of the stress relaxation fixture shown in
men for a length of 4D 6 0.5D, where D = specimen diameter
Appendix X3 may be used.
and shall be centered 60.5D with respect to the point at which
6.4 Specimen contact load, current, and potential drop shall
the crossed specimens make contact. Beyond the load support
region (at center of the specimens), the specimens shall be be recorded for each specimen pair as they are brought into
initial contact and as the load increases. During subsequent
unsupported.
long-term testing at constant load or constant displacement,
6.3.3 Electrical connections to the ends of the specimens
specimen current and potential drop shall be measured at
shall be made by flexible leads to fixed terminals mounted on
appropriate intervals, no less frequent than ⁄10 of the duration
the fixture base.
of the test. For specimens exposed to elevated temperature, the
6.3.4 The specimens are brought into contact at a rate of 1
measurements may be performed at room temperature if
mm/min or less until contact is made. After physical contact is
required to achieve the specified accuracy.
established, the contact force is increased at a rate of 1 kg/min
with a maximum allowable lateral motion of 0.025 mm.
FRETTING SENSITIVITY
Contact force is increased until it reaches the lesser of the
following: 6.5 Specimen size and fixturing for initial engagement shall
be in accordance with 6.1 – 6.3.5. Additional requirements are
6.3.4.1 120 % of the force required to achieve contact
resistance of 1.0 mΩ. as follows:
6.3.4.2 2.0 kg (for standard specimen diamete
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