ASTM D6770-21

Standard Test Method for Abrasion Resistance of Textile Webbing (Hex Bar Method)

SIGNIFICANCE AND USE
5.1 The measurement of the resistance to abrasion of textile webbing is very complex. The resistance to abrasion is affected by many factors that include the inherent mechanical properties of the fibers; the dimensions of the fibers; the structure of the yarns; the construction of the webbing; the type, kind, and amount of treatment added to the fibers, yarns, or webbing; the nature of the abradant; the variable action of the abradant over the specimen area abraded; the tension on the specimen; the pressure between the specimen and the abradant; and the dimensional changes in the specimen.  
5.2 The resistance of textile webbing to abrasion as measured by this test method does not include all the factors which account for wear performance or durability in actual use. While the abrasion resistance stated in terms of the number of cycles and durability (defined as the ability to withstand deterioration or wearing out in use, including the effects of abrasion) are frequently related, the relationship varies with different end uses. Different factors may be necessary in any calculation of predicted durability from specific abrasion data.  
5.3 Laboratory tests may be reliable as an indication of relative end use in cases where the difference in abrasion resistance of various materials is large, but they should not be relied upon where differences in laboratory test findings are small. In general, the results should not be relied upon for prediction of performance during actual wear life for specific end uses unless there are data showing the specific relationship between laboratory abrasion tests and actual wear in the intended end use.  
5.4 These general observations apply to most webbings that are used in automotive, aerospace, industrial, and military applications.  
5.5 This test method can be used for acceptance testing of commercial shipments but comparisons should be made with caution because estimates of between-laboratory precision are incomplete.  
5.6 I...
SCOPE
1.1 This test method covers the determination of abrasion resistance of textile webbing using a hex bar abrasion tester.  
1.1.1 The resistance is expressed as a percentage of retained breaking strength.  
1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for information only and are not considered standard.  
1.3 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 establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.4 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

• Status: Published
• Publication Date: 30-Jun-2021
• ICS: 59.080.30 - Textile fabrics
• Technical Committee: D13 - Textiles
• Drafting Committee: D13.60 - Fabric Physical Test Methods B

Relations

• Refers: ASTM D6775-13(2024) - Standard Test Method for Breaking Strength and Elongation of Textile Webbing, Tape and Braided Material
• Effective Date: 01-Jan-2024
• Refers: ASTM D1776/D1776M-20 - Standard Practice for Conditioning and Testing Textiles
• Effective Date: 01-Feb-2020
• Refers: ASTM D6775-13(2017) - Standard Test Method for Breaking Strength and Elongation of Textile Webbing, Tape and Braided Material
• Effective Date: 15-Jul-2017
• Refers: ASTM D4850-13(2017) - Standard Terminology Relating to Fabrics and Fabric Test Methods
• Effective Date: 15-Jul-2017
• Refers: ASTM D123-17 - Standard Terminology Relating to Textiles
• Effective Date: 01-Mar-2017
• Refers: ASTM D1776/D1776M-16 - Standard Practice for Conditioning and Testing Textiles
• Effective Date: 01-Jan-2016
• Refers: ASTM D123-15b - Standard Terminology Relating to Textiles
• Effective Date: 15-Sep-2015
• Refers: ASTM D123-15a - Standard Terminology Relating to Textiles
• Effective Date: 01-Sep-2015
• Refers: ASTM D123-15 - Standard Terminology Relating to Textiles
• Effective Date: 01-Apr-2015
• Refers: ASTM D1776/D1776M-15 - Standard Practice for Conditioning and Testing Textiles
• Effective Date: 01-Feb-2015
• Refers: ASTM E177-14 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-May-2014
• Refers: ASTM D4850-13e1 - Standard Terminology Relating to Fabrics and Fabric Test Methods
• Effective Date: 01-Jul-2013
• Refers: ASTM D6775-13 - Standard Test Method for Breaking Strength and Elongation of Textile Webbing, Tape and Braided Material
• Effective Date: 01-Jul-2013
• Refers: ASTM D4850-13 - Standard Terminology Relating to Fabrics and Fabric Test Methods
• Effective Date: 01-Jul-2013
• Refers: ASTM D123-13ae1 - Standard Terminology Relating to Textiles
• Effective Date: 15-Jun-2013

Overview

ASTM D6770-21: Standard Test Method for Abrasion Resistance of Textile Webbing (Hex Bar Method) is an internationally recognized procedure developed by ASTM International. This test method specifies how to determine the abrasion resistance of textile webbing by employing a hex bar abrasion tester, providing valuable insight into the retained breaking strength of webbing materials after exposure to simulated wear. Textile webbing is used in critical sectors such as automotive, aerospace, industrial, and military applications, where both safety and material durability are vital considerations.

Key Topics

• Purpose of the Test: The primary goal is to measure the relative abrasion resistance of textile webbing, indicating how well a webbing sample retains breaking strength after abrasion.
• Abrasion Resistance Factors: Results can be influenced by fiber properties, yarn structure, webbing construction, treatments applied, abradant nature, tension and pressure during testing, and specimen dimensional stability.
• Measurement and Expression: Abrasion resistance is expressed as the percentage of retained breaking strength, contrasting the breaking forces of abraded and unabraded specimens.
• Precision and Limitations: Laboratory results provide a comparative measure of abrasion resistance but may not directly predict performance in end-use applications, especially where differences between materials are small. Comparisons between laboratories may be affected by limited interlaboratory precision data.

Applications

ASTM D6770-21 is essential for manufacturers, quality control managers, and end users who need to ensure the durability and performance of textile webbing in demanding environments. Practical applications include:

• Product Development: R&D teams use the test to compare new webbing materials or constructions for enhanced abrasion resistance.
• Quality Assurance: Manufacturers perform acceptance testing on commercial batches to verify compliance with abrasion performance requirements, supporting quality control protocols.
• Industry Sectors:
  • Automotive: Seat belts, cargo straps, and safety restraints where prolonged wear could affect performance.
  • Aerospace: Harnesses and tie-downs requiring consistent strength after repeated use.
  • Industrial: Lifting slings and securing straps exposed to abrasive surfaces.
  • Military: Equipment harnesses, tactical gear, and parachute webbings subjected to extreme conditions.

Related Standards

Several ASTM and other industry standards are referenced within and frequently used alongside ASTM D6770-21 to ensure comprehensive textile testing and standardization:

• ASTM D123: Terminology Relating to Textiles - provides definitions relevant to textile test methods.
• ASTM D1776/D1776M: Practice for Conditioning and Testing Textiles - outlines standardized atmospheric conditions for textile testing.
• ASTM D4850: Terminology Relating to Fabrics and Fabric Test Methods - further supports standardized language in fabric evaluation.
• ASTM D6775: Test Method for Breaking Strength and Elongation of Textile Webbing, Tape, and Braided Material - often used to determine baseline breaking strength before and after abrasion.
• ASTM E177: Practice for Use of the Terms Precision and Bias in ASTM Test Methods - supports proper statistical evaluation and comparison of laboratory test data.

Summary

Adhering to ASTM D6770-21 enables the reliable assessment of the abrasion resistance of textile webbing, improving the safety, durability, and quality of end-use products in critical industries. By using this standardized test method, organizations can benchmark webbing materials, support procurement decisions, and maintain product performance requirements, facilitating international trade and customer trust. For optimal test accuracy and industry compliance, users should reference related ASTM standards and ensure proper laboratory practices when applying the hex bar abrasion method.

Keywords: abrasion resistance, textile webbing, ASTM D6770, hex bar method, breaking strength, industrial textiles, quality control, textile testing standards.

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: D6770 − 21
Standard Test Method for
Abrasion Resistance of Textile Webbing (Hex Bar Method)
This standard is issued under the fixed designation D6770; 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* 3. Terminology
3.1 For all terminology relating to Fabrics, refer to Termi-
1.1 This test method covers the determination of abrasion
nology D4850.
resistance of textile webbing using a hex bar abrasion tester.
3.2 For all other terminology related to textiles, refer to
1.1.1 The resistance is expressed as a percentage of retained
Terminology D123.
breaking strength.
1.2 The values stated in SI units are to be regarded as
4. Summary of Test Method
standard. The values given in parentheses after SI units are
4.1 Abrasion resistance is measured by subjecting the speci-
provided for information only and are not considered standard.
men to unidirectional reciprocal rubbing over a specific bar
under specified conditions of tension, stroke length and time.
1.3 This standard does not purport to address all of the
Resistance to abrasion is evaluated by determining the percent
safety concerns, if any, associated with its use. It is the
retention of breaking force of an abraded specimen compared
responsibility of the user of this standard to establish appro-
to an unabraded specimen.
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
5. Significance and Use
1.4 This international standard was developed in accor-
5.1 The measurement of the resistance to abrasion of textile
dance with internationally recognized principles on standard-
webbing is very complex.The resistance to abrasion is affected
ization established in the Decision on Principles for the
bymanyfactorsthatincludetheinherentmechanicalproperties
Development of International Standards, Guides and Recom-
of the fibers; the dimensions of the fibers; the structure of the
mendations issued by the World Trade Organization Technical
yarns; the construction of the webbing; the type, kind, and
Barriers to Trade (TBT) Committee.
amount of treatment added to the fibers, yarns, or webbing; the
nature of the abradant; the variable action of the abradant over
2. Referenced Documents
the specimen area abraded; the tension on the specimen; the
pressure between the specimen and the abradant; and the
2.1 ASTM Standards:
dimensional changes in the specimen.
D123 Terminology Relating to Textiles
D1776/D1776M Practice for Conditioning and Testing Tex-
5.2 The resistance of textile webbing to abrasion as mea-
tiles
sured by this test method does not include all the factors which
D4850 Terminology Relating to Fabrics and Fabric Test
accountforwearperformanceordurabilityinactualuse.While
Methods
the abrasion resistance stated in terms of the number of cycles
D6775 TestMethodforBreakingStrengthandElongationof
and durability (defined as the ability to withstand deterioration
Textile Webbing, Tape and Braided Material
or wearing out in use, including the effects of abrasion) are
E177 Practice for Use of the Terms Precision and Bias in
frequently related, the relationship varies with different end
ASTM Test Methods
uses. Different factors may be necessary in any calculation of
predicted durability from specific abrasion data.
5.3 Laboratory tests may be reliable as an indication of
This test method is under the jurisdiction ofASTM Committee D13 on Textiles
relative end use in cases where the difference in abrasion
and is the direct responsibility of Subcommittee D13.60 on Fabric Test Methods,
resistance of various materials is large, but they should not be
Specific.
relied upon where differences in laboratory test findings are
Current edition approved July 1, 2021. Published September 2021. Originally
small. In general, the results should not be relied upon for
approved in 2002. Last previous edition approved in 2019 as D6770–07(2019).
DOI: 10.1520/D6770-21.
prediction of performance during actual wear life for specific
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
end uses unless there are data showing the specific relationship
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
between laboratory abrasion tests and actual wear in the
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. intended end use.
*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
D6770 − 21
5.4 These general observations apply to most webbings that steel shall have a cold drawn finish and a Rockwell Hardness
are used in automotive, aerospace, industrial, and military of B-91 to B-101. The edges of the hexagonal rods shall not
applications. have any burrs, nicks or scale.
6.1.3 The mechanism “D” shall have a nominal outside
5.5 This test method can be used for acceptance testing of
diameter of 400 mm (16 in.) or be some mechanism able to
commercial shipments but comparisons should be made with
produceareciprocatingmotionofatleast300mm(12in.)over
caution because estimates of between-laboratory precision are
the hex rod with a suitable means for attaching the specimen to
incomplete.
be tested without damage to the specimen.
5.6 If there are differences of practical significance between
6.1.4 The crank-arm “F” shall be attached to the mechanism
reported test results for two laboratories (or more), compara-
“D” and to the driver disk “E” in such a manner that when the
tive tests should be performed to determine if there is a
specimen is attached to the mechanism, the specimen during
statistical bias between them, using competent statistical assis-
the test will oscillate over the hexagonal rod the required
tance. As a minimum, use samples for such comparative tests
distance during each stroke and at the required rate (see 10.4).
thatareashomogenousaspossible,drawnfromthesamelotof
6.1.5 The hexagonal rod shall be so placed that specimen
material as the samples that resulted in disparate results during
“A” with the weight attached to one end and the other end
initial testing, and randomly assigned in equal numbers to each
passing over the hexagonal rod and attached to the drive
laboratory. The test results from the laboratories involved
mechanism will form an angle “H” of 85 6 2°.
should be compared using a statistical test for unpaired data, at
a probability level chosen prior to the testing series. If bias is
6.2 Tensile Testing Machine , CRE-Type equipped with
found, either its cause must be found and corrected, or future
split-drum webbing clamps as described in Test Method
test results must be adjusted in consideration of the known
D6775.
bias.
7. Sampling and Test Specimens
6. Apparatus
7.1 Lot Sample—Take a lot sample as directed in the
6.1 Webbing Abrasion Tester—The webbing abrasion tester
applicable material specification. In absence of such a specifi-
consists of a suitable mechanism that will provide a recipro-
cation randomly select five rolls or pieces to constitute the lot
cating motion of the webbing over a standardized hex bar. One
sample.
end of each specimen is attached to the mechanism and the
other end passing over a hexagonal steel rod is attached to a 7.2 Laboratory Sampling Unit—As a laboratory sampling
weight.The hexagonal rod is so fixed as to subject the webbing unit take from each roll or piece one piece of webbing that is
specimen to abrasion on two adjacent edges as the drum moves 2.8 m (3.0 yd) in length.
the specimen across the rod. One example of such a mecha-
7.3 Test Specimens—From each laboratory sampling unit,
nism is a reciprocating drum as illustrated in Fig. 1.
cut 2 test specimens 1.4 m (1.5 yd) in length. Mark one
6.1.1 Mass “B” shall be 900 660g(2lb 6 2 oz) for
specimen “A” for abraded and the other “U” for unabraded.
webbing with breaking strengths up to 4500 N (1000 lb), 1800
7.3.1 When the lot or shipment consists of less than 5 rolls
660g(4lb 6 2 oz) for breaking strengths of 4500 to 13 500
or pieces, randomly select 5 test specimens that represent all
N (1000 to 3000 lb) and 2400 6 60 g (5.2 lb 6 2 oz) for
rolls or pieces in the lot or shipment.
breaking strengths over 13 500 N (3000 lb).
6.1.2 Steel hexagonal rods “C” shall be 6.35 6 0.03 mm
(0.250 6 0.001 in.) when measured across opposite flat sides
and the radius shall be 0.5 6 0.2 mm (0.020 6 0.008 in.). The Apparatus and accessories are commercially available.
FIG. 1 Webbing Abrasion Tester
D6770 − 21
7.4 Ensure specimens are free of folds, creases, or wrinkles. 10.7.1 Attach the split drum webbing clamps in the tensile
Avoid getting oil, water, grease, and so forth, on the specimens tester and set the distance between them to 250 mm (10 in.)
when handling. center to center.
10.7.2 Set the testing speed to 75 6 25 mm/min (3 6 1
in./min).
8. Conditioning
8.1 Conditionthetestspecimenstomoistureequilibriumfor
11. Calculation
testing in the standard atmosphere for tes
...

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.
Designation: D6770 − 07 (Reapproved 2019) D6770 − 21
Standard Test Method for
Abrasion Resistance of Textile Webbing (Hex Bar Method)
This standard is issued under the fixed designation D6770; 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 Scope*
1.1 This test method covers the determination of abrasion resistance of textile webbing using a hex bar abrasion tester.
1.1.1 The resistance is expressed as a percentage of retained breakbreaking strength.
1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for
information only and are not considered standard.
1.3 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 establish appropriate safety, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.4 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.
2. Referenced Documents
2.1 ASTM Standards:
D123 Terminology Relating to Textiles
D1776/D1776M Practice for Conditioning and Testing Textiles
D4850 Terminology Relating to Fabrics and Fabric Test Methods
D6775 Test Method for Breaking Strength and Elongation of Textile Webbing, Tape and Braided Material
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
2.2 Other Standard:
Federal Standard 191A, Method 4108 “Strength and Elongation, Breaking; Textile Webbing, Tape and Braided Items”
3. Terminology
3.1 For all terminology relating to Fabrics, refer to Terminology D4850.
3.2 The following terms are relevant to this standard: abrasion, abrasion cycle, breaking force, standard atmosphere for
preconditioning textiles, standard atmosphere for testing textiles, stroke, in hex bar abrasion testing, webbing.
This test method is under the jurisdiction of ASTM Committee D13 on Textiles and is the direct responsibility of Subcommittee D13.60 on Fabric Test Methods, Specific.
Current edition approved Dec. 1, 2019July 1, 2021. Published December 2019September 2021. Originally approved in 2002. Last previous edition approved in 20152019
as D6770–07(2015).D6770–07(2019). DOI: 10.1520/D6770-07R19.10.1520/D6770-21.
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
D6770 − 21
3.2 For all other terminology related to textiles, refer to Terminology D123.
4. Summary of Test Method
4.1 Abrasion resistance is measured by subjecting the specimen to unidirectional reciprocal rubbing over a specific bar under
specified conditions of tension, stroke length and time. Resistance to abrasion is evaluated by determining the percent retention
of breaking force of an abraded specimen compared to an unabraded specimen.
5. Significance and Use
5.1 The measurement of the resistance to abrasion of textile webbing is very complex. The resistance to abrasion is affected by
many factors that include the inherent mechanical properties of the fibers; the dimensions of the fibers; the structure of the yarns;
the construction of the webbing; the type, kind, and amount of treatment added to the fibers, yarns, or webbing; the nature of the
abradant; the variable action of the abradant over the specimen area abraded; the tension on the specimen; the pressure between
the specimen and the abradant; and the dimensional changes in the specimen.
5.2 The resistance of textile webbing to abrasion as measured by this test method does not include all the factors which account
for wear performance or durability in actual use. While the abrasion resistance stated in terms of the number of cycles and
durability (defined as the ability to withstand deterioration or wearing out in use, including the effects of abrasion) are frequently
related, the relationship varies with different end uses. Different factors may be necessary in any calculation of predicted durability
from specific abrasion data.
5.3 Laboratory tests may be reliable as an indication of relative end use in cases where the difference in abrasion resistance of
various materials is large, but they should not be relied upon where differences in laboratory test findings are small. In general,
the results should not be relied upon for prediction of performance during actual wear life for specific end uses unless there are
data showing the specific relationship between laboratory abrasion tests and actual wear in the intended end use.
5.4 While there has not been extensive interlaboratory testing prior to development of this standard, there has been some quality
control testing by manufacturers. An intralaboratory test was conducted to initiate this test method, using a single product. This
data will be used to determine a preliminary statement on precision and bias. Subsequent to approval of this standard, a formalized
interlaboratory procedure will be initiated under the direction of a professional statistician and will produce a research report.
Samples used in this controlled test will be representative of end use applications.
5.4 These general observations apply to most webbings that are used in automotive, aerospace, industrial, and military
applications.
5.5 This test method can be used for acceptance testing of commercial shipments but comparisons should be made with caution
because estimates of between-laboratory precision are incomplete.
5.6 If there are differences of practical significance between reported test results for two laboratories (or more), comparative tests
should be performed to determine if there is a statistical bias between them, using competent statistical assistance. As a minimum,
use samples for such comparative tests that are as homogenous as possible, drawn from the same lot of material as the samples
that resulted in disparate results during initial testing, and randomly assigned in equal numbers to each laboratory. The test results
from the laboratories involved should be compared using a statistical test for unpaired data, at a probability level chosen prior to
the testing series. If bias is found, either its cause must be found and corrected, or future test results must be adjusted in
consideration of the known bias.
6. Apparatus
6.1 Webbing Abrasion Tester—The webbing abrasion tester consists of a suitable mechanism that will provide a reciprocating
motion of the webbing over a standardized hex bar. One end of each specimen is attached to the mechanism and the other end
passing over a hexagonal steel rod is attached to a weight. The hexagonal rod is so fixed as to subject the webbing specimen to
abrasion on two adjacent edges as the drum moves the specimen across the rod. One example of such a mechanism is a
reciprocating drum as illustrated in Fig. 1.
D6770 − 21
FIG. 1 Webbing Abrasion Tester
6.1.1 Mass “B” shall be 900 6 60 g (2 lb 6 2 oz) for webbing with breaking strengths up to 4500 N (1000 lb), 1800 6 60 g (4
lb 6 2 oz) for breaking strengths of 4500 to 13 500 N (1000 to 3000 lb) and 2400 6 60 g (5.2 lb 6 2 lb)oz) for breaking strengths
over 13 500 N (3000 lb).
6.1.2 Steel hexagonal rods “C” shall be 6.35 6 0.03 mm (0.250 6 0.001 in.) when measured across opposite flat sides and the
radius shall be 0.5 6 0.2 mm (0.020 6 0.008 in.). The steel shall have a cold drawn finish and a Rockwell Hardness of B-91 to
B-101. The edges of the hexagonal rods shall not have any burrs, nicks or scale.
6.1.3 The mechanism “D” shall have a nominal outside diameter of 400 mm (16 in.) or be some mechanism able to produce a
reciprocating motion of at least 300 mm (12 in.) over the hex rod with a suitable means for attaching the specimen to be tested
without damage to the specimen.
6.1.4 The crank-arm “F” shall be attached to the mechanism “D” and to the driver disk “E” in such a manner that when the
specimen is attached to the mechanism, the specimen during the test will oscillate over the hexagonal rod the required distance
during each stroke and at the required rate (see 10.4).
6.1.5 The hexagonal rod shall be so placed that specimen “A” with the weight attached to one end and the other end passing over
the hexagonal rod and attached to the drive mechanism will form an angle “H” of 85 6 2° “H”.2°.
6.2 Tensile Testing Machine , CRE-Type equipped with split-drum webbing clamps as described in Federal Test Method
D6775191A, Method 4108.
7. Sampling and Test Specimens
7.1 Lot Sample—Take a lot sample as directed in the applicable material specification. In absence of such a specification randomly
select five rolls or pieces to constitute the lot sample.
7.2 Laboratory Sampling Unit—As a laboratory sampling unit take from each roll or piece one piece of webbing that is 2.8 m (3.0
yd) in length.
7.3 Test Specimens—From each laboratory sampling unit, cut 2 test specimens 1.4 m (1.5 yd) in length. Mark one specimen “A”
for abraded and the other “U” for unabraded.
7.3.1 When the lot or shipment consists of less than 5 rolls or pieces, randomly select 5 test specimens that represent all rolls or
pieces in the lot or shipment.
Available from Superintendent of Documents, Government Printing Office, Washington, DC 20402.Apparatus and accessories are commercially available.
D6770 − 21
7.4 Ensure specimens are free of folds, creases, or wrinkles. Avoid getting oil, water, grease, and so forth, on the specimens when
handling.
8. Conditioning
8.1 Condition the test specimens to moisture equilibrium for testing in the standard atmosphere for testing textiles in accordance
with Practice D1776/D1776M or, if applicable, in the specified atmosphere in which the testing is to be performed.
8.2 In the event of dispute concerning the results of tests that may be affected by the moisture content, test specimens shall be
preconditioned by bringing them to approximate moisture equilibrium in the standard atmosphere for preconditioning textiles in
accordance with Practice D1776/D1776M.
9. Preparation and Calibration of Test Apparatus
9.1 Ensure the test machine is on a level, sturdy surface and free from vibration.
9.2 For hexagonal rods a manufacturer’s certificate of compliance shall be acceptable as to the requirements as described in 6.1.2.
10. Procedure
10.1 Condition the “A” test specimens in the standard atmosphere for testing textiles, in accordance with Section 8.
10.2 Attach the required mass (6.1.1) to one end of the test specimen, pass the other end over the hexagonal rod and attach to the
drum. The length of the test specimens shall be adjusted, without altering the original length, so that the test specimens will
oscillate across the hexagon rod and each end of the abraded area will be equidistant from the ends of the test specimens.
10.3 The edges of each new hexagonal rod shall be identified as 1 through 6, and rotated after each use so that no abrading edges
are used more than once. Use edge 1 and two2 for one test specimen, edge 3 and 4 for a second test specimen, edges 5 and 6 for
a third test specimen, and then discard the rod.
10.4 Oscillate the mechanism so that the test specimens are given a 300 6 25 mm (12 6 1 in.) traverse over the rod at the rate
of 1 6 .03 strokes (0.5 cycles) per second for 5000 strokes (2500 cycles). One single stroke is 300 6 25 mm (12 6 1 in.) in one
direction only.
10.5 After the machine has stopped at the predetermined number of cycles remove the test specimens from the abrading machine.
10.6 Continue as directed in 10.2 – 10.5 until all the required specimens have been abraded for each laboratory sampling unit.
10.7 Determine the breaking force of the abraded specimens (A) and the unabraded specimens (U) for each laboratory sampling
unit in the lot to the nearest 1 % as directed in Fed-Std-191A,Test Method 4108D6775 set as follows:
10.7.1 Attach the split drum webbing clamps in the tensile tester and set the distance between them to 250 mm (10 in.) center to
center.
10.7.2 Set the testing speed to 75 6 25 mmmm/min (3 6 1 in./min).
11. Calculation
11.1 Calculate the average breaking force for the lot of the abraded test specimens from the results of the laboratory sampling
units.
11.2 Calculate the average breaking force for the lot of the unabraded test specimens from the results of the laboratory sampling
units.
D6770 − 21
11.3 Calculate the percentage of retained breaking force to the nearest 1 % for the lot using Eq 1:
100A
AR 5 (1)
U
where:
AR = abrasion resistance, %,
A = average breaking force of the abraded specimens, N (lb), and
U = average breaking force of the unabraded specimens, N (lb).
11.3.1 When data are automatically computer processed, calculations are generally contained in the associated software. It is
recommended that computer-processed data be verified against known property values and its software described in the report.
12. Report
12.1 Report that the abrasion resistance was determined in accordance with Test Method D6770. Describe the material or product
sampled.
12.2 Report the following information for the laboratory sampling unit and for the lot as applicable to a material specification or
contract order:
12.2.1 Abrasion resistance, percent retained in breaking force.
12.2.2 Breaking force of abraded test specimens.
12.2.3 Breaking force of unabraded test specimens.
12.2.4 For computer-processed data, identify the program (software) used.
13. Precision and Bias
13.1 An intralaboratory test was conducted for the determination of precision and bias of this test method. The results of the test
are attached as Table 1.
NOTE 1—Because the intralaboratory test included less than the recommended five laboratories, estimates of precision data may be either underestimated
or overestimated to a considerable extent and should be used with special caution.
13.1 Precision—A statement on the The precision of this test method is being developed. The based on an intralaboratory study,
conducted to initiate the procedure now recognized as ASTM D6770results will be included when available., Test Method for
Abrasion Resistance of Textile Webbing (Hex Bar Method). Each of six volunteer laboratories or operators were asked to test one
material. Every “test result” represents the average of five individual determinations, and all participants were instructed to report
five replicate test results for each material.
13.1.1 Repeatability limit (r)—The difference between repetitive results obtained by the same operator in a given laboratory
applying the same test method with the same apparatus under constant operating conditions on identical test material within short
intervals of time would in the long run, in the normal and correct operation of the test method, exceed the following values only
in one case in 20.
13.1.1.1 Repeatability can be interpreted as maximum difference between two results, obtained under repeatability conditions, that
is accepted as plausible due to random causes under normal and correct operation of the test method.
13.1.1.2 Repeatability limits are listed in Tables 1 and 2.
Apparatus and accessories are commercially available.Supporting data have been filed at ASTM International Headquarters and may be obtained by requesting Research
Report RR:D13-2001. Contact ASTM Customer Service at [e-mail].
D6770 − 21
TABLE 1 Raw Data from Intralaboratory Test
Material
Material 1—Before 2—After
Abrasion Abrasion
Lab. Opr. Test 1 Test 2 Test 3 Test 4 Test 5 Opr. Sum
Set 1 1 4.720 4.820 4.600 4.700 4.600 23.440 4.620
2 4.600 4.720 4.700 4.720 4.680 23.420 4.640
3 4.580 4.720 4.720 4.560 4.720 23.300 4.620
4 4.740 4.740 4.520 4.720 4.740 23.460 4.500
5 4.700 4.660 4.600 4.700 4.680 23.340 4.620
6 4.600 4.680 4.500 4.480 4.540 22.800 4.380
Lab Sum 139.760
Set 2 1 4.600 4.720 4.600 4.720 4.680 23.320 4.420
2 4.680 4.700 4.660 4.700 4.640 23.380 4.520
3 4.660 4.720 4.660 4.660 4.640 23.340 4.460
4 4.760 4.740 4.640 4.660 4.380 23.180 4.540
5 4.680 4.700 4.740 4.620 4.680 23.420 4.500
6 4.640 4.720 4.740 4.840 4.780 23.720 4.600
Lab Sum 140.360
Set 3 1 4.680 4.720 4.700 4.700 4.680 23.480 4.500
2 4.620 4.600 4.680 4.680 4.620 23.200 4.500
3 4.560 4.740 4.560 4.680 4.720 23.260 4.660
4 4.740 4.680 4.720 4.580 4.460 23.180 4.600
5 4.700 4.700 4.660 4.620 4.700 23.360 4.540
6 4.700 4.720 4.760 4.720 4.720 23.620 4.580
Lab Sum 140.120
Set 4 1 4.820 4.680 4.680 4.660 4.700 23.540 4.500
2 4.700 4.720 4.660 4.700 4.700 23.480 4.500
3 4.680 4.480 4.700 4.720 4.680 23.260 4
...