ASTM D1425/D1425M-14
(Test Method)Standard Test Method for Evenness of Textile Strands Using Capacitance Testing Equipment
Standard Test Method for Evenness of Textile Strands Using Capacitance Testing Equipment
SIGNIFICANCE AND USE
6.1 This test method for the determination of evenness of textile strands is used extensively for acceptance testing of commercial shipments of filament or spun staple yarn, comber laps, roving, sliver, or tops.
6.2 Values of strand evenness are also used in quality control, process optimization, and together with yarn strength measurements, as the first appraisal of a strand's quality. A low evenness value is, in general, preferred. Higher evenness values generally indicate poor yarn manufacturing practices, lower yarn strength, and poorer fabric appearance. Experience has shown that the relationship of evenness to the prediction of yarn performance and to fabric appearance is not a simple one. An evenness value must, therefore, be used cautiously and be supplemented by additional evenness information, such as mid-term and long-term mass variations, thin, thick, and nep imperfection counts, diagram chart spectrogram chart, length variation curve, and histogram analyses.
6.3 Continuous filament yarns should be tested for mass variation on evenness testers that are specifically designed to test this yarn type; failure to do so will result in inaccurate test results. Further, low-twist, continuous filament yarns tend to flatten to a ribbon configuration while passing through the sensor of a capacitance instrument. This flattening effect will cause false mass variation measurements by the capacitive sensor (commonly referred to as shape effect). Evenness testers that are specifically designed to test continuous filament yarns insert a false twist to the yarn strand during testing to overcome the flattening effect and thus ensure accurate mass variation measurements.
6.4 Strands made from fiber blends should be tested only if the different fibers are uniformly distributed throughout the strand. Non-uniform blending may cause a higher reading of mass variation than the true value if the component fibers differ in dielectric constant.
6.5 Evenness values obtai...
SCOPE
1.1 This test method covers the indirect measurement of evenness (mass variation) of non-conductive textile strands, including top, comber lap, sliver, roving, and yarn produced from staple fibers and continuous filament yarns, by means of capacitance testing equipment.
1.2 Strands made from fiber blends can be tested using this test method only if the different fibers are uniformly distributed throughout the strand.
1.3 The test method provides numeric values for the measurement and evaluation of short-, mid-, and long-term mass variations of the tested strand in terms of frequently occurring faults classified as thin places, thick places, and neps and graphical representations of evenness values in the form of diagram charts, spectrograms, length variation curves, and histograms.
1.4 The values stated in either SI units or inch-pound units are to be regarded separately as standard. 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 non-conformance with the standard.
1.5 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: D1425/D1425M − 14
Standard Test Method for
Evenness of Textile Strands Using Capacitance Testing
1
Equipment
This standard is issued under the fixed designation D1425/D1425M; 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 D2258 Practice for Sampling Yarn for Testing
D4849 Terminology Related to Yarns and Fibers
1.1 This test method covers the indirect measurement of
E177 Practice for Use of the Terms Precision and Bias in
evenness (mass variation) of non-conductive textile strands,
ASTM Test Methods
including top, comber lap, sliver, roving, and yarn produced
E691 Practice for Conducting an Interlaboratory Study to
from staple fibers and continuous filament yarns, by means of
Determine the Precision of a Test Method
capacitance testing equipment.
1.2 Strands made from fiber blends can be tested using this
3. Terminology
testmethodonlyifthedifferentfibersareuniformlydistributed
3.1 Definitions:
throughout the strand.
3.1.1 The following terms are relevant to this standard:
1.3 The test method provides numeric values for the mea-
electric constant; evenness; imperfections; length between, L ;
b
surement and evaluation of short-, mid-, and long-term mass
length capacitance zone, L ; mass variation; mean deviation of
c
variations of the tested strand in terms of frequently occurring
evenness, U%; sample length L ; strand; strand irregularity;
s
faults classified as thin places, thick places, and neps and
and total imperfections.
graphical representations of evenness values in the form of
3.1.2 For definitions of other textile terms used in this test
diagram charts, spectrograms, length variation curves, and
method, refer to Terminology D123 and Terminology D4849.
histograms.
1.4 The values stated in either SI units or inch-pound units 4. Basic Principles of Test Method
are to be regarded separately as standard. The values stated in
4.1 Properties of strand irregularity measured along its
each system may not be exact equivalents; therefore, each
length are measured in terms of mass variation.
system shall be used independently of the other. Combining
4.2 The direct method of evenness testing utilizes the
values from the two systems may result in non-conformance
techniqueofcuttingandweighingstrandsegmentsoflength L
with the standard. b
and is the reference method of determining evenness (mass
1.5 This standard does not purport to address all of the
variation). Utilization of the capacitance measurement tech-
safety concerns, if any, associated with its use. It is the
nique is an indirect testing method.The accuracy of an indirect
responsibility of the user of this standard to establish appro-
method of testing can be judged by a comparison of evenness
priate safety and health practices and determine the applica-
values between it and the direct method (cutting and weigh-
bility of regulatory limitations prior to use.
ing).
2. Referenced Documents 4.3 In capacitance testing, a high frequency electric field is
2
generated in the space between a pair of capacitor plates
2.1 ASTM Standards:
(measuring slots). If the mass of a strand moving between the
D123 Terminology Relating to Textiles
plates changes, the electrical field between the plates changes
D1776 Practice for Conditioning and Testing Textiles
accordingly, and results in electrical signal output variation
proportional to the mass variation of the strand.
1
This test method is under the jurisdiction ofASTM Committee D13 on Textiles
4.4 Evenness is always expressed as variation between
and is the direct responsibility of Subcommittee D13.58 on Yarns and Fibers.
successive lengths L and over a total length Ls. When the L
c
Current edition approved July 1, 2014. Published August 2014. Originally
ε1
evenness is measured, it corresponds to the length capacitance
approved in 1956. Last previous edition approved in 2009 as D1425/D1425M-09 .
DOI: 10.1520/D1425_D1425M-14.
zone width, i.e., 8 mm [0.3 in.] for yarns, 12 mm [0.5 in.] for
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
rovings and fine slivers, and 20 mm [0.8 in.] for slivers that are
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
referred to as short-term evenness. Longer-term evenness may
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. also be evaluated by electronically increasing the L .
c
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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D1425/D1425M −
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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: D1425/D1425M − 09 D1425/D1425M − 14
Standard Test Method for
UnevennessEvenness of Textile Strands Using Capacitance
1
Testing Equipment
This standard is issued under the fixed designation D1425/D1425M; 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
ε NOTE—Footnotes A and B were added to Table 1 in April 2012.
1. Scope
1.1 This test method covers the indirect measurement of evenness (mass variation) of non-conductive textile strands, including
top, comber lap, sliver, roving, and yarn produced from staple fibers and continuous filament yarns, by means of capacitance testing
equipment.
1.2 Strands made from fiber blends can be tested using this test method only if the different fibers are uniformly distributed
throughout the strand.
1.3 The test method provides numeric values for the measurement and evaluation of short-, mid-, and long-term mass variations
of the tested strand in terms of frequently occurring faults classified as thin places, thick places, and neps and graphical
representations of evenness values in the form of diagram charts, spectrograms, length variation curves, and histograms.
1.4 The values stated in either SI units or inch-pound units are to be regarded separately as standard. 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 non-conformance with the standard.
1.5 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.
2. Referenced Documents
2
2.1 ASTM Standards:
D123 Terminology Relating to Textiles
D1776 Practice for Conditioning and Testing Textiles
D2258 Practice for Sampling Yarn for Testing
D4849 Terminology Related to Yarns and Fibers
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
3. Terminology
3.1 Definitions:
3.1.1 electric constant, n—in textile capacitance testing, the change in the electrical field as measured by the sensors
(capacitors) of an evenness instrument when a non-conductive textile strand travels between capacitor plates.
1
This test method is under the jurisdiction of ASTM Committee D13 on Textiles and is the direct responsibility of Subcommittee D13.58 on Yarns and Fibers.
Current edition approved July 1, 2009July 1, 2014. Published August 2009August 2014. Originally approved in 1956. Discontinued May 2005 and reinstated Last previous
ε1
edition approved in 2009 as D1425/D1425M-09. DOI: 10.1520/D1425_D1425M-09-09 . DOI: 10.1520/D1425_D1425M-14.
2
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 Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
3.1.1.1 Discussion—
The dielectric change is measured as the ratio of the amount of stored energy between the capacitors without a strand and during
the movement of a strand through the sensor zone and is in direct proportion to the mass variation that is output to a diagram chart.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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D1425/D1425M − 14
3.1.1 The following terms are relevant to this standard: electric constant; evenness; imperfections; length between, L ; length
b
capacitance zone, L ; mass variation; mean deviation of evenness, U%; sample length L ; strand; strand irregularity; and total
c s
imperfections.
3.1.2 evenness, CV% (or U%), n— in textiles, the coefficient of mass variation derived from the standard deviation of the mass
variation of a specified strand length (L ) over the mass variation (formerly known as unevenness).
s
3.1.2.1 Discussion—
For strands with normal mass variation distribution, the relationship between CV% and U% is U% is multiplied by 1.25. Although
both CV% and U% are used as values of evenness, CV% is considered more accurate CV% is gradually repla
...
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