ASTM D3937-94

NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
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Designation: D 3937 – 94
Standard Test Method for
Crimp Frequency of Man-Made Staple Fibers
This standard is issued under the fixed designation D 3937; 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 induced either naturally, mechanically, or chemically.
3.1.1.1 Discussion—Crimp has many characteristics,
1.1 This test method covers the determination of the crimp
among which are its amplitude, frequency, index, and type. In
frequency of man-made staple fibers. This test method is
this test method, crimp is characterized by a change in the
applicable to all crimped provided the crimp can be viewed
directional rotation of a line tangent to the fiber as the point of
two-dimensionally as a sine-wave configuration.
tangent progresses along the fiber. Two changes in rotation
NOTE 1—For determination of crimp in wool, refer to Test Method
constitute one unit of crimp.
D 2491.
3.1.2 crimp frequency, n—in man-made staple fibers, the
1.1.1 It should be recognized that yarn manufacturing pro-
number of crimps or waves per unit length of extended or
cesses or treatments to manufactured yarns can influence or
straightened fiber.
modify crimp in fiber. Hence, the value for crimp of fibers
3.1.3 crimp index, n—an indirect measure of the amplitude
taken from spun yarns may be different than that of the same
of crimp.
fiber prior to the manufacturing or treatment processes.
3.1.3.1 Discussion—Crimp index is calculated as the differ-
1.2 Three options are provided for preparation of the speci-
ence in the distance between two points on the fiber as it lies
mens. Option One (preferred) uses single fibers for the speci-
in an unstretched condition in one plane and the distance
mens with a low magnification available, Option Two (optional
between the same two points when the fiber is straightened
for staple or tow samples) uses fiber chips as the specimens,
under a specified tension expressed as a percentage of the
and Option Three uses projected images of single fibers.
unstretched distance. To improve reproducibility, the un-
1.3 The values stated in SI units are to be regarded as the
stretched distance may be measured under a specified, very low
standard. The inch-pound units in parentheses are for informa-
tension to align the fiber in one plane.
tion only.
3.1.4 fiber chip, n—in man-made textiles, staple fibers that
1.4 This standard does not purport to address all of the
are massed together as a unit and that maintain a single
safety concerns, if any, associated with its use. It is the
geometry or alignment.
responsibility of the user of this standard to establish appro-
3.1.5 For definitions of other textile terms used in this test
priate safety and health practices and determine the applica-
method, refer to Terminology D 123.
bility of regulatory limitations prior to use.
4. Summary of Test Method
2. Referenced Documents
4.1 For Option One, a fiber specimen of man-made staple is
2.1 ASTM Standards:
placed on a short pile or plush surface. The crimps along the
D 123 Terminology Relating to Textiles
entire length of the specimen is counted. After the specimen is
D 1776 Practice for Conditioning Textiles for Testing
counted, the fiber is straightened without deformation and its
D 2258 Practice for Sampling Yarn for Testing
uncrimped length measured. Crimp frequency is reported as
D 3333 Practice for Sampling Man-Made Staple Fibers,
the number of crimps per unit of extended length.
Sliver, or Tow for Testing
4.2 For Option Two, the number of crimps is counted in
fiber chip specimens. The specimen length is measured on
3. Terminology
fibers taken from each of the chips.
3.1 Definitions:
4.3 For Option Three, the fiber specimen is mounted be-
3.1.1 crimp, n—in a textile strand, the undulations, wavi-
tween microscope slides. The image of the specimen is
ness, or succession of bends, curls, or waves in the strand
projected and its crimp is counted. The extended length of the
specimen is measured as in Option One.
This test method is under the jurisdiction of ASTM Committee D13 on Textiles 4.4 In each option, the crimp frequency is calculated from
and is the direct responsibility of Subcommittee D13.58 on Yarn and Fiber Test
the numbers of crimp counted and the fiber lengths measured.
Methods.
Current edition approved Dec. 15, 1994. Published April 1995. Originally
5. Significance and Use
published as D 3937 – 80. Last previous edition D 3937 – 90.
Annual Book of ASTM Standards, Vol 07.01. 5.1 Test Method D 3937 for the determination of crimp
Annual Book of ASTM Standards, Vol 07.02.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
D 3937
sampling plan with a meaningful producer’s risk, consumer’s risk,
frequency of man-made staple fibers may be used for the
acceptable quality level, and limiting quantity level.
acceptance testing of commercial shipments but caution is
advised since between-laboratory precision is known to be
7.2 Laboratory Sample—As a laboratory sample for accep-
poor. Comparative tests conducted as directed in 5.1.1 may be
tance testing, take at random from each shipping container in
advisable.
the lot sample the number of laboratory sampling units as
5.1.1 In case of a dispute arising from differences in
directed in an applicable material specification or other agree-
reported test results when using Test Method D 3937 for
ment between the purchaser and the supplier such as an
acceptance testing of commercial shipments, the purchaser and
agreement to use Practice D 3333 or Practice D 2258. Prefer-
the supplier should conduct comparative tests to determine if
ably, the same number of laboratory sampling units are taken
there is a statistical bias between their laboratories. Competent
from each shipping container in the lot sample. If differing
statistical assistance is recommended for the investigation of
numbers of laboratory sampling units are to be taken from
bias. As a minimum, the two parties should take a group of test
shipping containers in the lot sample, determine at random
specimens which are as homogeneous as possible and which
which shipping containers are to have each number of labora-
are from a lot of material of the type in question. The test
tory units drawn.
specimens should then be randomly assigned in equal numbers
7.2.1 For Staple Fiber—Take 50-g samples from laboratory
to each laboratory for testing. The average results from the two
sampling units.
laboratories should be compared using Students’s t-test and an
7.2.2 For Sliver (or Top) or Tow—Take 1 m from the
acceptable probability level chosen by the two parties before
leading end which has a clean, uniform appearance.
the testing began. If a bias is found, either its cause must be
7.3 Test Specimens—From each laboratory sampling unit,
found and corrected or the purchaser and the supplier must
take twenty-five specimens at random. For Options One and
agree to interpret future test results with consideration to the
Three, each specimen is a fiber, and for Option Two, the
known bias.
specimen is a fiber chip. If the standard deviation determined
5.2 This test method is used for quality control. It is an
for the ten specimens is more than a value agreed upon
unsophisticated procedure which is particularly useful in de-
between the purchaser and the supplier, continue testing in
tecting major differences in crimp frequency. This test method
groups of ten specimens from the same laboratory sampling
is not considered to be useful in research and development
unit until the standard deviation for all specimens tested is not
where minor differences or more complete crimp characteriza-
more than the agreed to value or, by agreement, stop testing
tion, including amplitude and index, may be necessary.
after a specified number.
5.3 Crimp in fiber affects the carding and subsequent
8. Conditioning
processing of the fiber into either a yarn or a nonwoven fabric.
5.4 Staple crimp in fiber will also affect the bulk or 8.1 Condition the specimens as directed in Practice D 1776.
openness of a yarn and therefore the hand and visual appear-
9. Procedure
ance of the finished textile product.
9.1 Test conditioned specimens in the standard atmosphere
6. Apparatus
for testing textiles, which is 21 6 1°C (70 6 2°F) and 65 6
2 % relative humidity.
6.1 Short Pile or Plush Surface, of a color contrasting with
9.2 Specimen Preparation Options:
color of fibers under investigation.
9.2.1 Option One Single Fiber (Preferred)—Carefully re-
6.2 Magnifier, with no greater than 103 magnification,
move 25 fibers at random from each laboratory sampling unit,
optional for counting crimp of fibers of low linear density in
using tweezers. Place these spe
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