ASTM D6770-02
(Test Method)Standard Test Method for Abrasion Resistance of Textile Webbing (Hex Bar Method)
Standard Test Method for Abrasion Resistance of Textile Webbing (Hex Bar Method)
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 break strength.
1.2 The values stated in either SI units or inch-pound units are to be regarded separately as the standard. Within the text, the inch-pound units are shown in parentheses. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in nonconformance with this test method.
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 and health practices and determine the applicability of regulatory limitations prior to use.
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: D 6770 – 02
Standard Test Method for
Abrasion Resistance of Textile Webbing (Hex Bar Method)
This standard is issued under the fixed designation D 6770; 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 of both. For the hex bar abrasion method a cycle is comprised
of two strokes.
1.1 This test method covers the determination of abrasion
3.1.3 breaking force, n—the maximum force applied to a
resistance of textile webbing using a hex bar abrasion tester.
material carried to rupture. (Compare breaking point, breaking
1.1.1 The resistance is expressed as a percentage of retained
strength.)
break strength.
3.1.4 standard atmosphere for preconditioning textiles,
1.2 The values stated in either SI units or inch-pound units
n—a set of controlled conditions having a temperature not over
are to be regarded separately as the standard. Within the text,
50°C (122°F), with respective tolerance of 61°C (2°F), and a
the inch-pound units are shown in parentheses. The values
relative humidity of 5 to 25 6 2 % for the selected humidity,
stated in each system may not be exact equivalents; therefore,
so that drying can be achieved prior to conditioning in the
each system shall be used independently of the other. Combin-
standard atmosphere for testing textiles.
ing values from the two systems may result in nonconformance
3.1.5 standard atmosphere for testing textiles,
with this test method.
n—laboratory conditions for testing fibers, yarns, and fabrics in
1.3 This standard does not purport to address all of the
which air temperature and relative humidity are maintained at
safety concerns, if any, associated with its use. It is the
specific levels with established tolerances.
responsibility of the user of this standard to establish appro-
3.1.5.1 Discussion—Textile materials are used in a number
priate safety and health practices and determine the applica-
of specific end-use applications that frequently require different
bility of regulatory limitations prior to use.
testing temperatures and relative humidities. Specific condi-
2. Referenced Documents
tioning and testing of textiles for end-product requirements can
be carried out as defined in Practice D 1776.
2.1 ASTM Standards:
3.1.6 stroke, n—in hex bar abrasion testing, one-half of an
D 123 Terminology Relating to Textiles
abrasion cycle that consists of one forward or one backward
D 1776 Practice for Conditioning and Testing Textiles
motion.
2.2 Other Standard:
3.1.7 webbing, n—in textiles, a stout narrow fabric with a
Federal Standard 191, Method 4108 “Strength and Elonga-
2 2
mass per unit area of at least 0.5 kg/m (0.1 lb/ft ) for each 25.4
tion, Breaking; Textile Webbing, Tape and Braided
mm (1 in.) of width. (Compare narrow fabric, ribbon, and
Items”
tape.)
3. Terminology
3.2 For definitions of other textile terms used in this test
method, refer to Terminology D 123.
3.1 Definitions:
3.1.1 abrasion, n—the wearing away of any part of a
4. Summary of Test Method
material by rubbing against another surface.
4.1 Abrasion resistance is measured by subjecting the speci-
3.1.2 abrasion cycle, n—one or more movements of an
men to unidirectional reciprocal rubbing over a specific bar
abradant across a material surface, or the material surface
under specified conditions of tension, stroke length and time.
across the abradant, that permits a return to its starting position.
Resistance to abrasion is evaluated by determining the percent
3.1.2.1 Discussion—The abrasion cycle is dependent on the
retention of breaking force of an abraded specimen compared
programmed motions of the abrasion machine and the test
to an unabraded specimen.
standard used. It may consist of one back-and-forth unidirec-
tional movement or one circular movement, or a combination
5. Significance and Use
5.1 The measurement of the resistance to abrasion of textile
This test method is under the jurisdiction of ASTM Committee D13 on Textiles webbing is very complex. The resistance to abrasion is affected
and is the direct responsibility of Subcommittee D13.60 on Fabrics, Specific.
by many factors that include the inherent mechanical properties
Current edition approved Feb. 10, 2002. Published March 2002.
of the fibers; the dimensions of the fibers; the structure of the
Annual Book of ASTM Standards, Vol 07.01.
yarns; the construction of the webbing; the type, kind, and
Available from Superintendent of Documents, Government Printing Office,
Washington, DC 20402.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D 6770
amount of treatment added to the fibers, yarns, or webbing; the end of each specimen is attached to the mechanism and the
nature of the abradant; the variable action of the abradant over other end passing over a hexagonal steel rod is attached to a
the specimen area abraded; the tension on the specimen; the weight. The hexagonal rod is so fixed as to subject the webbing
pressure between the specimen and the abradant; and the specimen to abrasion on two adjacent edges as the drum moves
dimensional changes in the specimen. the specimen across the rod. One example of such a mecha-
5.2 The resistance of textile webbing to abrasion as mea- nism is a reciprocating drum as illustrated in Fig. 1.
sured by this test method does not include all the factors which 6.1.1 Mass “B” shall be 900 6 60g(2lb 6 2 oz) for
account for wear performance or durability in actual use. While webbing with breaking strengths up to 4500 N (1000 lb), 1800
the abrasion resistance stated in terms of the number of cycles 6 60g(4lb 6 2 oz) for breaking strengths of 4500 to 13 500
and durability (defined as the ability to withstand deterioration N (1000 to 3000 lb) and 2400 6 60 g (5.2 6 2 lb) for breaking
or wearing out in use, including the effects of abrasion) are strengths over 13 500 N (3000 lb).
frequently related, the relationship varies with different end 6.1.2 Steel hexagonal rods “C” shall be 6.35 6 0.03 mm
uses. Different factors may be necessary in any calculation of (0.250 6 0.001 in.) when measured across opposite flat sides
predicted durability from specific abrasion data. and the radius shall be 0.5 6 0.2 mm (0.020 6 0.008 in.). The
5.3 Laboratory tests may be reliable as an indication of steel shall have a cold drawn finish and a Rockwell Hardness
relative end use in cases where the difference in abrasion of B-91 to B-101. The edges of the hexagonal rods shall not
resistance of various materials is large, but they should not be have any burrs, nicks or scale.
relied upon where differences in laboratory test findings are 6.1.3 The mechanism “D” shall have a nominal outside
small. In general, the results should not be relied upon for diameter of 400 mm (16 in.) or be some mechanism able to
prediction of performance during actual wear life for specific produce a reciprocating motion of at least 300 mm (12 in.) over
end uses unless there are data showing the specific relationship the hex rod with a suitable means for attaching the specimen to
between laboratory abrasion tests and actual wear in the be tested without damage to the specimen.
intended end use. 6.1.4 The crank-arm “F” shall be attached to the mechanism
5.4 While there has not been extensive interlaboratory “D” and to the driver disk “E” in such a manner that when the
testing prior to development of this standard, there has been specimen is attached to the mechanism, the specimen during
some quality control testing by manufacturers. An intralabora- the test will oscillate over the hexagonal rod the required
tory test was conducted to initiate this test method, using a distance during each stroke and at the required rate (see 10.4).
single product. This data will be used to determine a prelimi- 6.1.5 The hexagonal rod shall be so placed that specimen
nary statement on precision and bias. Subsequent to approval “A” with the weight attached to one end and the other end
of this standard, a formalized interlaboratory procedure will be passing over the hexagonal rod and attached to the drive
initiated under the direction of a professional statistician and mechanism will form an angle of 85 6 2° “H”.
will produce a research report. Samples used in this controlled 6.2 Tensile Testing Machine, CRE-Type equipped with split-
test will be representative of end use applications. drum webbing clamps as described in Federal Test Method
5.5 These general observations apply to most webbings that 191b, Method 4108.
are used in automotive, aerospace, industrial, and military
7. Sampling and Test Specimens
applications.
7.1 Lot Sample—Take a lot sample as directed in the
5.6 This test method can be used for acceptance testing of
applicable material specification. In absence of such a specifi-
commercial shipments but comparisons should be made with
cation randomly select five rolls or pieces to constitute the lot
caution because estimates of between-laboratory precision are
incomplete. sample.
7.2 Laboratory Sampling Unit—As a laboratory sampling
5.7 If there are differences of practical significance between
reported test results for two laboratories (or more), compara- unit take from each roll or piece one piece of webbing that is
2.8 m (3.0 yd) in length.
tive tests should be performed to determine if there is a
statistical bias between them, using competent statistical assis- 7.3 Test Specimens—From each laboratory sampling unit,
cut 2 test specimens 1.4 m (1.5 yd) in length. Mark one
tance. As a minimum, use samples for such comparative tests
that are as homogenous as possible, drawn from the same lot of specimen “A” for abraded and the other “U” for unabraded.
7.3.1 When the lot or shipment consists of less than 5 rolls
material as the samples that resulted in disparate results during
or pieces, randomly select 5 test specimens that represent all
initial testing, and randomly assigned in equal numbers to each
rolls or pieces in the lot or shipment.
laboratory. The test results from the laboratories involved
7.4 Ensure specimens are free of folds, creases, or wrinkles.
should be compared using a statistical test for unpaired data, as
Avoid getting oil, water, grease, and so forth, on the specimens
a probability level chosen prior to the testing series. If bias is
when handling.
found, either its cause must be found and corrected, or future
test results must be adjusted in consideration of the known
8. Conditioning
bias.
8.1 Condition the test specimens to moisture equilibrium for
6. Apparatus
testing in the standard atmosphere for testing textiles in
6.1 Webbing Abrasion Tester—The webbing abrasion tester accordance with Practice D 1776 or, if applicable, in the
consists of a suitable mechanism that will provide a recipro- specified atmosphere in which the testing is to be performed.
cating motion of the webbing over a standardized hex bar. One 8.2 In the event of dispute concerning the results of tests
D 6770
FIG. 1 Webbing Abrasion Tester
that may be affected by the moisture content, test specimen(s) 10.4 Oscillate the mechanism so that the test specimen(s)
shall be preconditioned by bringing them to approximate are given a 300 6 25 mm (12 6 1 in.) traverse over the rod at
moisture equilibrium in the standard atmosphere for precondi- the rate of 1 6 .03 strokes (0.5 cycles) per second for 5000
tioning textiles in accordance with Practice D 1776. strokes (2500 cycles). One single stroke is 300 6 25 mm (12
6 1 in.) in one direction only.
9. Preparation and Calibration of Test Apparatus
10.5 After the machine has stopped at the predetermined
9.1 Ensure the test machine is on a level, sturdy surface and number of cycles remove the test specimen(s) from the
free from vibration. abrading machine.
9.2 For hexagonal rods a manufacturer’s certificate of com- 10.6 Continue as directed in 10.2–10.5 until all the required
pliance shall be acceptable as to the requirements as described specimens have been abraded for each laboratory sampling
in 6.1.2. unit.
10.7 Determine the breaking force of the abraded specimens
10. Procedure
(A) and the unabraded specimens (U) for each laboratory
sampling unit in the lot to the nearest 1 % as directed in
10.1 Condition the “A” test specimens in the standard
Fed-Std-191, Method 4108 set as follows:
atmosphere for testing textiles, in accordance with Section 8.
10.7.1 Attach the split drum webbing clamps in the tensile
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 tester and set the distance between them to 250 mm (10 in.)
center to center.
to the drum. The length of the test specimen(s) shall be
adjusted, without altering the original length, so that the test 10.7.2 Set the testing speed to 75 6 25 mm (3 6 1 in./min).
specimen(s) will oscillate across the hexagon rod and each end
11. Calculation
of the abraded area will be equidistant from the ends of the test
specimen(s). 11.1 Calculate the average breaking force for the lot of the
10.3 The edges of each new hexagonal rod shall be identi- abraded test specimens from the results of the laboratory
fied as 1 through 6, and rotated after each use so that no sampling units.
abrading edges are used more than once. Use edge 1 and two 11.2 Calculate the average breaking force for the lot of the
for one test specimen, edge 3 and 4 for a second test specimen, unabraded test specimens from the results of the laboratory
edges 5 and 6 for a third test specimen, and then discard the sampling units.
rod. 11.3 Calculate the percentage of retained breaking force to
D 6770
the nearest 1 % for the lot using Eq 1: 12.2.2 Breaking force of abraded test specimens.
12.2.3 Breaking force of unabraded test specimens.
100A
AR 5 (1)
12.2.4 For computer-processed data, identify the program
U
(software) used.
where:
AR = abrasion resistance, %,
13. Precision and Bias
A = average breaking force of the abraded specimens, N
13.1 An intralaboratory test was conducted for the determi-
(lb), and
nation of precision and bias of this test method. The results of
U = average breaking force of the unabraded specimens,
the test are attached as Table 1.
N (lb).
11.3.1 When data are automatically computer processed,
NOTE 1—Because the intralaboratory test included less than the recom-
mended five laboratories, estimates of precision data may be either
calculations are generally contained in the associated soft
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.