ASTM D6770-07(2011)
(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)
SIGNIFICANCE AND USE
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.
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.
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.
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 ...
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 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.
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Designation: D6770 − 07(Reapproved 2011)
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.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 4. Summary of Test Method
1.1 This test method covers the determination of abrasion 4.1 Abrasionresistanceismeasuredbysubjectingthespeci-
resistance of textile webbing using a hex bar abrasion tester. men to unidirectional reciprocal rubbing over a specific bar
1.1.1 Theresistanceisexpressedasapercentageofretained under specified conditions of tension, stroke length and time.
break strength. Resistance to abrasion is evaluated by determining the percent
retention of breaking force of an abraded specimen compared
1.2 This standard does not purport to address all of the
to an unabraded specimen.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
5. Significance and Use
priate safety and health practices and determine the applica-
5.1 The measurement of the resistance to abrasion of textile
bility of regulatory limitations prior to use.
webbingisverycomplex.Theresistancetoabrasionisaffected
bymanyfactorsthatincludetheinherentmechanicalproperties
2. Referenced Documents
of the fibers; the dimensions of the fibers; the structure of the
2.1 ASTM Standards:
yarns; the construction of the webbing; the type, kind, and
D123Terminology Relating to Textiles
amountoftreatmentaddedtothefibers,yarns,orwebbing;the
D1776Practice for Conditioning and Testing Textiles
nature of the abradant; the variable action of the abradant over
D4850Terminology Relating to Fabrics and Fabric Test
the specimen area abraded; the tension on the specimen; the
Methods
pressure between the specimen and the abradant; and the
2.2 Other Standard:
dimensional changes in the specimen.
Federal Standard 191, Method 4108 “Strength and
5.2 The resistance of textile webbing to abrasion as mea-
Elongation, Breaking;TextileWebbing,Tape and Braided
suredbythistestmethoddoesnotincludeallthefactorswhich
Items”
accountforwearperformanceordurabilityinactualuse.While
the abrasion resistance stated in terms of the number of cycles
3. Terminology
and durability (defined as the ability to withstand deterioration
3.1 For all terminology relating to Fabrics, refer to Termi-
or wearing out in use, including the effects of abrasion) are
nology D4850.
frequently related, the relationship varies with different end
3.2 The following terms are relevant to this standard:
uses. Different factors may be necessary in any calculation of
abrasion, abrasion cycle, breaking force, standard atmosphere
predicted durability from specific abrasion data.
for preconditioning textiles, standard atmosphere for testing
5.3 Laboratory tests may be reliable as an indication of
textiles, stroke, in hex bar abrasion testing, webbing.
relative end use in cases where the difference in abrasion
3.3 For all other terminology related to textiles, refer to
resistance of various materials is large, but they should not be
Terminology D123.
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
ThistestmethodisunderthejurisdictionofASTMCommitteeD13onTextiles
endusesunlesstherearedatashowingthespecificrelationship
and is the direct responsibility of Subcommittee D13.60 on Fabric Test Methods,
between laboratory abrasion tests and actual wear in the
Specific.
intended end use.
CurrenteditionapprovedMay1,2011.PublishedJuly2011.Originallyapproved
in 2002. Last previous edition approved in 2007 as D6770–07. DOI: 10.1520/
5.4 While there has not been extensive interlaboratory
D6770-07R11.
testing prior to development of this standard, there has been
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
some quality control testing by manufacturers.An intralabora-
Standards volume information, refer to the standard’s Document Summary page on
tory test was conducted to initiate this test method, using a
the ASTM website.
single product. This data will be used to determine a prelimi-
Available from Superintendent of Documents, Government Printing Office,
Washington, DC 20402. nary statement on precision and bias. Subsequent to approval
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6770 − 07 (2011)
ofthisstandard,aformalizedinterlaboratoryprocedurewillbe N(1000to3000lb)and2400 660g(5.2 62lb)forbreaking
initiated under the direction of a professional statistician and strengths over 13500 N (3000 lb).
will produce a research report. Samples used in this controlled 6.1.2 Steel hexagonal rods “C” shall be 6.35 6 0.03 mm
test will be representative of end use applications. (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
5.5 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.
5.6 This test method can be used for acceptance testing of
6.1.3 The mechanism “D” shall have a nominal outside
commercial shipments but comparisons should be made with
diameter of 400 mm (16 in.) or be some mechanism able to
caution because estimates of between-laboratory precision are
produceareciprocatingmotionofatleast300mm(12in.)over
incomplete.
thehexrodwithasuitablemeansforattachingthespecimento
be tested without damage to the specimen.
5.7 If there are differences of practical significance between
reported test results for two laboratories (or more), compara- 6.1.4 Thecrank-arm“F”shallbeattachedtothemechanism
tive tests should be performed to determine if there is a “D” and to the driver disk “E” in such a manner that when the
specimen is attached to the mechanism, the specimen during
statistical bias between them, using competent statistical assis-
tance. As a minimum, use samples for such comparative tests the test will oscillate over the hexagonal rod the required
distance during each stroke and at the required rate (see 10.4).
thatareashomogenousaspossible,drawnfromthesamelotof
material as the samples that resulted in disparate results during 6.1.5 The hexagonal rod shall be so placed that specimen
“A” with the weight attached to one end and the other end
initialtesting,andrandomlyassignedinequalnumberstoeach
laboratory. The test results from the laboratories involved passing over the hexagonal rod and attached to the drive
mechanism will form an angle of 85 6 2° “H”.
shouldbecomparedusingastatisticaltestforunpaireddata,at
a probability level chosen prior to the testing series. If bias is 4
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 Federal Test
test results must be adjusted in consideration of the known
Method 191b, Method 4108.
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
catingmotionofthewebbingoverastandardizedhexbar.One
sample.
end of each specimen is attached to the mechanism and the
7.2 Laboratory Sampling Unit—As a laboratory sampling
other end passing over a hexagonal steel rod is attached to a
unit take from each roll or piece one piece of webbing that is
weight.Thehexagonalrodissofixedastosubjectthewebbing
2.8 m (3.0 yd) in length.
specimentoabrasionontwoadjacentedgesasthedrummoves
7.3 Test Specimens—From each laboratory sampling unit,
the specimen across the rod. One example of such a mecha-
cut 2 test specimens 1.4 m (1.5 yd) in length. Mark one
nism is a reciprocating drum as illustrated in Fig. 1.
specimen “A” for abraded and the other “U” for unabraded.
6.1.1 Mass “B” shall be 900 660g(2lb 6 2 oz) for
webbing with breaking strengths up to 4500 N (1000 lb), 1800
660g(4lb 6 2 oz) for breaking strengths of 4500 to 13500 Apparatus and accessories are commercially available.
FIG. 1 Webbing Abrasion Tester
D6770 − 07 (2011)
7.3.1 When the lot or shipment consists of less than 5 rolls 10.7.1 Attach the split drum webbing clamps in the tensile
or pieces, randomly select 5 test specimens that represent all tester and set the distance between them to 250 mm (10 in.)
rolls or pieces in the lot or shipment. center to center.
10.7.2 Setthetestingspeedto75 625mm(3 61in./min).
7.4 Ensurespecimensarefreeoffolds,creases,orwrinkles.
Avoidgettingoil,water,grease,andsoforth,onthespecimens
11. Calculation
when handling.
11.1 Calculate the average breaking force for the lot of the
8. Conditioning
abraded test specimens from the results of the laboratory
8.1 Conditionthetestspecimenstomoistureequilibriumfor
sampling units.
testing in the standard atmosphere for testing textiles in
11.2 Calculate the average breaking force for the lot of the
accordance with Practice D1776 or, if applicable, in the
unabraded test specimens from the results of the laboratory
specified atmosphere in which the testing is to be performed.
sampling units.
8.2 In the event of dispute concerning the results of tests
11.3 Calculate the percentage of retained breaking force to
that may be affected by the moisture content, test specimens
the nearest 1 % for the lot using Eq 1:
shall be preconditioned by bringing them to approximate
100A
moisture equilibrium in the standard atmosphere for precondi-
AR 5 (1)
U
tioning textiles in accordance with Practice D1776.
where:
9. Preparation and Calibration of Test Apparatus
AR = abrasion resistance, %,
9.1 Ensurethetestmachineisonalevel,sturdysurfaceand
A = average breaking force of the abraded specimens, N
free from vibration.
(lb), and
9.2 For hexagonal rods a manufacturer’s certificate of com-
U = average breaking force of the unabraded specimens, N
pliance shall be acceptable as to the requirements as described (lb).
in 6.1.2.
11.3.1 When data are automatically computer processed,
calculationsaregenerallycontainedintheassociatedsoftware.
10. Procedure
It is recommended that computer-processed data be verified
10.1 Condition the “A” test specimens in the standard
againstknownpropertyvaluesanditssoftwaredescribedinthe
atmosphere for testing textiles, in accordance with Section 8.
report.
10.2 Attach the required mass (6.1.1) to one end of the test
specimen,passtheotherendoverthehexagonalrodandattach
12. Report
tothedrum.Thelengthofthetestspecimensshallbeadjusted,
12.1 Report that the abrasion resistance was determined in
without altering the original length, so that the test specimens
accordance with Test Method D6770. Describe the material or
will oscillate across the hexagon rod and each end of the
product sampled.
abraded area will be equidistant from the ends of the test
12.2 Report the following information for the laboratory
specimens.
sampling unit and for the lot as applicable to a material
10.3 The edges of each new hexagonal rod shall be identi-
specification or contract order:
fied as 1 through 6, and rotated after each use so that no
12.2.1 Abrasion resistance, percent retained in breaking
abrading edges are used more than once. Use edge 1 and two
force.
foronetestspecimen,edge3and4forasecondtestspecimen,
12.2.2 Breaking force of abraded test specimens.
edges 5 and 6 for a third test specimen, and then discard the
12.2.3 Breaking force of unabraded test specimens.
rod.
12.2.4 For computer-processed data, identify the program
10.4 Oscillate the mechanism so that the test specimens are
(software) used.
given a 300 6 25 mm (12 6 1 in.) traverse over the rod at the
rateof1 6.03strokes(0.5cycles)persecondfor5000strokes
13. Precision and Bias
(2500 cycles). One single stroke is 300 6 25 mm (12 6 1 in.)
13.1 An intralaboratory test was conducted for the determi-
in one direction only.
nation of precision and bias of this test method. The results of
10.5 After the machine has stopped at the predetermined
the test are attached as Table 1.
number of cycles remove the test specimens from the abrading
NOTE 1—Because the intralaboratory test included less than the
machine.
recommended five laboratories, estimates of precision data may be either
underestimated or overestimated to a considerable extent and should be
10.6 Continue as directed in 10.2-10.5 until all the required
used with special caution.
specimens have been abraded for each laboratory sampling
unit. 13.2 Precision—A statement on the precision of this test
method is being developed. The results will be included when
10.7 Determinethebreakingforceoftheabradedspecimens
available.
(A) and the unabraded specimens (U) for each laboratory
sampling unit in the lot to the nearest 1% as directed in 13.3 Bias—Theprocedureofthistestmethodprovidesatest
Fed-Std-191, Method 4108 set as follows: value that can be defined only in terms of this test method.
D6770 − 07 (2011)
TABLE 1 Raw Data from Intralaboratory Test
Material 1—Before Abrasion Material 2—After Abrasion
Total Opr.
Lab. Opr. Test 1 Test 2 Test 3 Test 4 Test 5 Opr. Sum Test 1 Test 2 Test 3 Test 4 Test 5 Opr. Sum
Sum
Set 1 1 4.720 4.820 4.600 4.700 4.600 23.440 4.620 4.460 4.680 4.600 4.620 22.980 46.420
2 4.600 4.720 4.700 4.720 4.680 23.420 4.640 4.600 4.580 4.680 4.600 23.100 46.520
3 4.580 4.720 4.720 4.560 4.720 23.300 4.620 4.480 4.400 4.520 4.480 22.500 45.800
4 4.740 4.740 4.520 4.720 4.740 23.460 4.500 4.420 4.640 4.540 4.620 22.720 46.180
5 4.700 4.660 4.600 4.700 4.680 23.340 4.620 4.620 4.500 4.520 4.380 22.640 45.980
6 4.600 4.680 4.500 4.480 4.540 22.800 4.380 4.480 4.520 4.400 4.560 22.340 45.140
Lab Sum 139.760 136.280 276.040
Set 2 1 4.600 4.720 4.600 4.720 4.680 23.320 4.420 4.220 4.180 4.320 4.280 21.420 44.740
2 4.680 4.700 4.660 4.700 4.640 23.380 4.520 4.500 4.560 4.520 4.640 22.740 46.120
3 4.660 4.720 4.660 4.660 4.640 23.340 4.460 4.540 4.640 4.500 4.580 22.720 46.060
4 4.760 4.740 4.640 4.660 4.380 23.180 4.540 4.620 4.6
...
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