ASTM B896-10(2015)

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 and health practices, and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 30-Sep-2015
• ICS: 29.050 - Superconductivity and conducting materials
• Technical Committee: B02 - Nonferrous Metals and Alloys
• Drafting Committee: B02.11 - Electrical Contact Test Methods

Standards Content (Sample)

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: B896 − 10 (Reapproved 2015)
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.Anumber 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:
B539Test Methods for Measuring Resistance of Electrical
characterization of conductor material connectability on the
basis of measurements of parameters important to the design Connections (Static Contacts)
B542Terminology Relating to Electrical Contacts andTheir
and performance of electrical contacts and connections to and
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 Provisionismadeformeasurementoftheconnectability
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-
miningtheabilityofamaterialtoestablishandmaintainstable
tions.
low resistance electrical contact under the influence of dete-
1.4 Thesetestmethods,usingstandardizedspecimengeom-
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
4.1 Contact Resistance—Contact resistance is measured as
standard. No other units of measurement are included in this
force is increased between conductors in a crossed-rod contact
standard.
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
4.2 Fretting Sensitivity—Contactresistanceofacrossed-rod
by the manufacturer, to establish appropriate safety and health
pair is measured at constant normal force while a microscopic
practices, and determine the applicability of regulatory limi-
oscillitory tangential motion is applied at the contact interface.
tations prior to use.
The number of applied motion cycles required to induce
contact resistance instability is determined. The test may be
performedatelevatedtemperatureorincorrosiveenvironment.
These test methods are under the jurisdiction of ASTM Committee B02 on
Nonferrous Metals and Alloys and are the direct responsibility of Subcommittee
B02.11 on Electrical Contact Test Methods. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Oct. 1, 2015. Published October 2015. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
ɛ1
approved in 1999. Last previous edition approved in 2010 as B896– 10 . DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/B0896-10R15. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
B896 − 10 (2015)
4.3 Compressive Relaxation—Change of applied contact 6.3.4.1 120% of the force required to achieve contact
force with time, at fixed engagement displacement of crossed- resistance of 1.0 mΩ.
wire specimens, is measured. The test may be performed at
6.3.4.2 2.0 kg (for standard specimen diameter).
elevated temperature.
6.3.4.3 2.0 × D/2 kg (for nonstandard specimen diameter)
where D = diameter in mm.
5. Significance and Use
6.3.5 Instrumentation is provided for measurement of con-
5.1 These test methods develop comparative information
tact force, contact current, and contact voltage. The maximum
useful for the design of stationary contacts for wire, cable, and
open circuit voltage shall be 10 mV and the maximum current
other conductors.
shall be 100 mA.
5.2 Thesetestmethodsproduceresults,whicharefreeofthe
6.3.6 Constantloadlong-termtestingatthemaximumforce
influence of arbitrary connection systems.
(see 6.3.3) the specimen assembly may be fixed, maintaining
5.3 The influence of conductor surface pretreatments and the contact force and the physical relationship between the
platings can be evaluated by these test methods.
specimens so as to allow controlled evaluation of the effects of
long-term environmental variables, such as temperature,
5.4 The influence of environmental factors, such as high
humidity, or gaseous ambient.
temperature and corrosive environment can be evaluated by
these test methods. 6.3.7 Constant displacement long-term testing at the maxi-
mum force (see 6.3.4), the specimen assembly may be fixed,
5.5 The results obtained by these test methods provide
maintainingthecontactdisplacementandthephysicalrelation-
guidance on connection system design parameters, such as
ship between the specimens so as to allow controlled evalua-
contact force and gas tightness requirements.
tion of the effects of long-term environmental variables, such
as temperature, humidity, or gaseous ambient under conditions
6. Test Methods
whereby the contact load is influenced by stress-relaxation
6.1 Thesetestmethodsprovideforstandardizationofspeci-
effects. Fixture design for constant displacement testing must
men geometry, contact loads, and other factors, which may
be rigid and matched in thermal expansion characteristics to
influence the results. Use of nonstandard specimens or proce-
the material being tested, such as to maintain displacement
dures may influence the validity of relative connectability
within 1% of the initial value for the temperature range in
comparisons based on the test results.
which it is used for the duration of the test. The rigidity
CROSSED WIRE CONTACT RESISTANCE—FIXED requirementmaybesatisfiedbyafixturewhosespringconstant
LOAD (force/unit displacement) is calculated to be no less than 200×
larger than the elastic spring constant of the specimen pair
6.2 The standard specimen shall be 2 mm (#12 AWG)
when fully engaged. The specimen spring constant is deter-
diameter wire, at least 25 mm long, and straight to within 1%.
mined by measuring the displacement required to decrease the
Specimens of nonstandard diameter may be used. Resulting
contact force to 1 kg from an initial 2 kg.
performance data only is considered valid for comparison with
results on same-size specimens, however.
6.3.8 For the purpose of environmental exposure in accor-
dance with 6.3.6 and 6.3.7, the fixturing shall be designed to
6.3 The apparatus consists of a fixture capable of perform-
maintain contact load within 62% over the range of applied
ing as follows:
temperature for the duration of the test. Fixturing shall be
6.3.1 Specimens are oriented perpendicular to one another.
designed symmetrically so as to preclude introduction of shear
Contact between the specimens occurs approximately at the
forces in the plane of the specimen contact interface as
center of each specimen (lengthwise).
temperature is changed.
6.3.2 Specimens are supported by flat or vee-groove, or
equivalent holders, so as to prevent bending due to applied
6.3.9 The specific design of the apparatus may vary, pro-
contact load. Specimen support fixture shall support the speci-
videdthatthefunctionalrequirementsaremet.Arepresentative
men for a length of 4D 6 0.5D, where D = specimen diameter
embodimentofaconstantloadcrossed-wirefixtureisprovided
and shall be centered 60.5D with respect to the point at which
in Appendix X1. For constant displacement crossed-wire
the crossed specimens make contact. Beyond the load support
testing, a variation of the stress relaxation fixture shown in
region (at center of the specimens), the specimens shall be
Appendix X3 may be used.
unsupported.
6.4 Specimen contact load, current, and potential drop shall
6.3.3 Electrical connections to the ends of the specimens
be recorded for each specimen pair as they are brought into
shall be made by flexible leads to fixed terminals mounted on
initial contact and as the load increases. During subsequent
the fixture base.
long-term testing at constant load or constant displacement,
6.3.4 The specimens are brought into contact at a rate of 1
specimen current and potential drop shall be measured at
mm/min or less until contact is made.After physical contact is
appropriate intervals, no less frequent than ⁄10 of the duration
established, the contact force is increased at a rate of 1 kg/min
ofthetest.Forspecimensexposedtoelevatedtemperature,the
with a maximum allowable lateral motion of 0.025 mm.
measurements may be performed at room temperature if
Contact force is increased until it reaches the lesser of the
following: required to achieve the specified accuracy.
B896 − 10 (2015)
FRETTING SENSITIVITY forcewhenchangingtemperaturefromtheloadingconditionto
the long-term dwell condition.
6.5 Specimen size and fixturing for initial engagement shall
6.7.1.4 Thespecimensarebroughtintocontactata
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
´1
Designation: B896 − 10 B896 − 10 (Reapproved 2015)
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.
ε NOTE—A Summary of Changes was added editorially in December 2010.
1. Scope*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 Material Safety Data
Sheet (MSDS)(SDS) for this product/material as provided by the manufacturer, to establish appropriate safety and health practices,
and determine the applicability of regulatory limitations prior to use.
2. Referenced Documents
2.1 ASTM Standards:
B539 Test Methods for Measuring Resistance of Electrical Connections (Static Contacts)
B542 Terminology Relating to Electrical Contacts and Their Use
3. Terminology
3.1 Definitions—Definitions of terms used in this test method are in accordance with Terminology B542.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 connectability, n—a combination of properties determining the ability of a material to establish and maintain stable low
resistance electrical contact under the influence of deteriorating environmental and operational factors.
3.2.2 fretting, n—accelerated surface damage occurring at the interface of contacting materials subjected to small oscillatory
displacements.
4. Summary of Test Method
4.1 Contact Resistance—Contact resistance is measured as force is increased between conductors in a crossed-rod contact pair
of the material(s) being tested. Held at the maximum specified force, test contacts may be exposed to temperature changes or
corrosive environments such as high humidity to observe the effects of such conditions on electrical contact resistance.
These test methods are under the jurisdiction of ASTM Committee B02 on Nonferrous Metals and Alloys and are the direct responsibility of Subcommittee B02.11 on
Electrical Contact Test Methods.
Current edition approved Oct. 1, 2010Oct. 1, 2015. Published October 2010October 2015. Originally approved in 1999. Last previous edition approved in 20052010 as
ɛ1
B896 – 99 (2005).10 . DOI: 10.1520/B0896-10E01.10.1520/B0896-10R15.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
B896 − 10 (2015)
4.2 Fretting Sensitivity—Contact resistance of a crossed-rod pair is measured at constant normal force while a microscopic
oscillitory tangential motion is applied at the contact interface. The number of applied motion cycles required to induce contact
resistance instability is determined. The test may be performed at elevated temperature or in corrosive environment.
4.3 Compressive Relaxation—Change of applied contact force with time, at fixed engagement displacement of crossed-wire
specimens, is measured. The test may be performed at elevated temperature.
5. 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.
6. Test Methods
6.1 These test methods provide for standardization of specimen geometry, contact loads, and other factors, which may influence
the results. Use of nonstandard specimens or procedures may influence the validity of relative connectability comparisons based
on the test results.
CROSSED WIRE CONTACT RESISTANCE—FIXED LOAD
6.2 The standard specimen shall be 2 mm (#12 AWG) diameter wire, at least 25 mm long, and straight to within 1 %. Specimens
of nonstandard diameter may be used. Resulting performance data only is considered valid for comparison with results on
same-size specimens, however.
6.3 The apparatus consists of a fixture capable of performing as follows:
6.3.1 Specimens are oriented perpendicular to one another. Contact between the specimens occurs approximately at the center
of each specimen (lengthwise).
6.3.2 Specimens are supported by flat or vee-groove, or equivalent holders, so as to prevent bending due to applied contact load.
Specimen support fixture shall support the specimen for a length of 4D 6 0.5D, where D = specimen diameter and shall be centered
60.5D with respect to the point at which the crossed specimens make contact. Beyond the load support region (at center of the
specimens), the specimens shall be unsupported.
6.3.3 Electrical connections to the ends of the specimens shall be made by flexible leads to fixed terminals mounted on the
fixture base.
6.3.4 The specimens are brought into contact at a rate of 1 mm/min or less until contact is made. After physical contact is
established, the contact force is increased at a rate of 1 kg/min with a maximum allowable lateral motion of 0.025 mm. Contact
force is increased until it reaches the lesser of the following:
6.3.4.1 120 % of the force required to achieve contact resistance of 1.0 mΩ.
6.3.4.2 2.0 kg (for standard specimen diameter).
6.3.4.3 2.0 × D/2 kg (for nonstandard specimen diameter) where D = diameter in mm.
6.3.5 Instrumentation is provided for measurement of contact force, contact current, and contact voltage. The maximum open
circuit voltage shall be 10 mV and the maximum current shall be 100 mA.
6.3.6 Constant load long-term testing at the maximum force (see 6.3.3) the specimen assembly may be fixed, maintaining the
contact force and the physical relationship between the specimens so as to allow controlled evaluation of the effects of long-term
environmental variables, such as temperature, humidity, or gaseous ambient.
6.3.7 Constant displacement long-term testing at the maximum force (see 6.3.4), the specimen assembly may be fixed,
maintaining the contact displacement and the physical relationship between the specimens so as to allow controlled evaluation of
the effects of long-term environmental variables, such as temperature, humidity, or gaseous ambient under conditions whereby the
contact load is influenced by stress-relaxation effects. Fixture design for constant displacement testing must be rigid and matched
in thermal expansion characteristics to the material being tested, such as to maintain displacement within 1 % of the initial value
for the temperature range in which it is used for the duration of the test. The rigidity requirement may be satisfied by a fixture
whose spring constant (force/unit displacement) is calculated to be no less than 200× larger than the elastic spring constant of the
specimen pair when fully engaged. The specimen spring constant is determined by measuring the displacement required to
decrease the contact force to 1 kg from an initial 2 kg.
B896 − 10 (2015)
6.3.8 For the purpose of environmental exposure in accordance with 6.3.6 and 6.3.7, the fixturing shall be designed to maintain
contact load within 62 % over the range of applied temperature for the duration of the test. Fixturing shall be designed
symmetrically so as to preclude introduction of shear forces in the plane of the specimen contact interface as temperature is
changed.
6.3.9 The specific design of the apparatus may vary, provided that the functional requirements are met. A representative
embodiment of a constant load crossed-wire fixture is provided in Appendix X1. For constant displacement crossed-wire testing,
a variation of the stress relaxation fixture shown in Appendix X3 may be used.
6.4 Specimen contact load, current, and potential drop shall be recorded for each specimen pair as they are brought into initial
contact and as the load increases. During subsequent long-term testing at constant load or constant displacement, specimen current
and potential drop shall be measured at appropriate intervals, no less frequent than ⁄10 of the duration of the test. For specimens
exposed to elevated temperature, the measurements may be performed at room temperature if required to achieve the specified
accuracy.
FRETTING SENSITIVITY
6.5 Specimen size and fixturing for initial engagement shall be in accordance with 6.1 – 6.3.5. Additional requirements are as
follows:
6.5.1 At a maximum force as determined in 6.3.4, the specimen load shall be fixed, maintaining the contact force for the balance
of the test.
...