Significance and Use
The measurement of the resistance to abrasion
of textile and other materials is very complex. The resistance to abrasion is
affected by many factors, such as the inherent mechanical properties of the
fibers; the dimensions of the fibers; the structure of the yarns; the
construction of the fabrics; and the type, kind, and amount of finishing
material added to the fibers, yarns, or fabric.
The
resistance to abrasion is also greatly affected by the conditions of the tests,
such as the nature of abradant; variable action of the abradant over the area
of specimen abraded, the tension of the specimen, the pressure between the
specimen and abradant, and the dimensional changes in the specimen.
Abrasion
tests are all subject to variation due to changes in the abradant during
specific tests. The abradant must accordingly be changed at frequent intervals
or checked periodically against a standard. With disposable abradants, the
abradant is used only once or changed after limited use. With permanent abradants
that use hardened metal or equivalent surfaces, it is assumed that the abradant
will not change appreciably in a specific series of tests, but obviously
similar abradants used in different laboratories will not likely change at the
same rate due to differences in usage. Permanent abradants may also change due
to pick up of finishing or other material from test fabrics and must
accordingly be cleaned at frequent intervals. The measurement of the relative
amount of abrasion may also be affected by the method of evaluation and may be
influenced by the judgment of the operator.
The
resistance of textile materials to abrasion as measured on a testing machine in
the laboratory is generally only one of several factors contributing to wear
performance or durability as experienced in the actual use of the material.
While “abrasion resistance” (often stated in terms of the number of cycles on a
specified machine, using a specified technique to produce a specified degree or
amount of abrasion) 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, and
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 performance 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, they
should not be relied upon for prediction of actual wear-life in specific end
uses unless there are data showing the specific relationship between laboratory
abrasion tests and actual wear in the intended end-use.
These
general observations apply to all types of fabrics, including woven, nonwoven,
and knit apparel fabrics, household fabrics, industrial fabrics, and floor
coverings. It is not surprising, therefore, to find that there are many
different types of abrasion testing machines, abradants, testing conditions,
testing procedures, methods of evaluation of abrasion resistance, and
interpretation of results.
All the
test methods and instruments so far developed for abrasion resistance may show
a high degree of variability in results obtained by different operators and in
different laboratories; however, they represent the methods now most widely in
use. This test method provides a comparative measurement of the resistance of
woven textile fabrics to abrasion, and may not necessarily predict the actyal
performance of fabrics in actual use.
If there
are differences of practical significance between reported test results for two
or more laboratories, comparative tests should be performed to determine if
there is a statistical bias between them, using competent statistical
assistance. As a minimum, test samples that are as homogeneous as possible,
drawn from the material from which the disparate test results were obtained,
and randomly assigned in equal numbers to each laboratory for testing. The test
results from the two laboratories 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.
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