ASTM D4120-95
(Test Method)Standard Test Method for Fiber Cohesion in Roving, Sliver, and Top in Dynamic Tests
Standard Test Method for Fiber Cohesion in Roving, Sliver, and Top in Dynamic Tests
SCOPE
1.1 This test method describes the measurement of fiber cohesion as the dynamic cohesive force required to maintain drafting in rovings, slivers or tops when they are subjected to stress induced by passing between pairs of drafting rolls of different surface speeds. The cohesive force is converted to cohesive tenacity based on the linear density of the material.
Note 1—For static tests refer to Test Method D 2612.
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: D 4120 – 95
Standard Test Method for
Fiber Cohesion in Roving, Sliver, and Top in Dynamic Tests
This standard is issued under the fixed designation D 4120; 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 3. Terminology
1.1 This test method describes the measurement of fiber 3.1 Definitions:
cohesion as the dynamic cohesive force required to maintain 3.1.1 fiber cohesion, n—in textiles, the interaction between
drafting in rovings, slivers or tops when they are subjected to two or more fibers due to the combined effects of the surface
stress induced by passing between pairs of drafting rolls of characteristics, length, crimp, finish, and linear density of the
different surface speeds. The cohesive force is converted to fibers. (Syn. cling, drag)
cohesive tenacity based on the linear density of the material. 3.1.1.1 Discussion—Cohesive interaction should not be
confused with adhesion or sticking together as with a glutinous
NOTE 1—For static tests refer to Test Method D 2612.
substance.
1.2 This standard does not purport to address all of the
3.1.2 cohesive force, n—in a textile strand, the force re-
safety concerns, if any, associated with its use. It is the
quired to overcome fiber cohesion as the strand is being
responsibility of the user of this standard to establish appro-
reduced in linear density.
priate safety and health practices and determine the applica-
3.1.2.1 Discussion—In dynamic tests, cohesive force is the
bility of regulatory limitations prior to use.
force required to maintain drafting in a roving, sliver, or top. In
static tests, cohesive force is measured while a test specimen is
2. Referenced Documents
held in fixed position between two slowly separating clamps.
2.1 ASTM Standards:
3.1.3 roving, n—a loose assemblage of fibers drawn or
D 123 Terminology Relating to Textiles
rubbed into a single strand, with very little twist. In spun yarn
D 519 Test Method for Length of Fiber in Wool Top
systems, the product of the stage, or stages, just prior to
D 1440 Test Method for Length and Length Distribution of
spinning.
Cotton Fibers (Array Method)
3.1.4 sliver, n—a continuous strand of loosely assembled
D 1447 Test Method for Length and Length Uniformity of
fibers that is approximately uniform in cross-sectional area and
Cotton Fibers by Fibrograph Measurement
without twist.
D 1575 Test Method for Fiber Length of Wool in Scoured
3.1.5 tenacity, n—in a tensile test, the force exerted on the
Wool and in Card Sliver
specimen based on the linear density of the unstrained speci-
D 1776 Practice for Conditioning Textiles for Testing
men.
D 2258 Practice for Sampling Yarn for Testing
3.1.5.1 Discussion—In this method, tenacity is a drafting
D 2612 Test Method for Fiber Cohesion in Sliver and Top in
tenacity, the stress required to slide or pull fibers apart without
Static Tests
drawing or stretching them.
D 3333 Practice for Sampling Man-Made Staple Fibers,
3.1.6 top, n—(1) worsted process—a sliver in which the
Sliver, or Tow for Testing
fibers have been parallelized, and usually combed; (2) man-
D 3660 Test Method for Staple Length of Man-Made Fi-
made fibers or tow to top process—a sliver obtained by
bers, Average and Distribution (Fiber Array Method)
drafting, along with breaking or cutting a multifilament tow.
D 3661 Test Method for Staple Length of Man-Made Fi-
(See also wool top.)
bers, Average and Distribution (Single-Fiber Length Ma-
3.1.7 For definitions of terms related to force and deforma-
chine Method)
tion in textiles refer to Terminology D 4848. For definitions of
D 4848 Terminology Relating to Force and Deformation
other textile terms used in this test method refer to Terminol-
Properties of Textiles
ogy D 123.
4. Summary of Test Method
This test method is under the jurisdiction of ASTM Committee D13 on Textiles
4.1 This test method provides an indication of the ability of
and is the direct responsibility of Subcommittee D13.58 on Yarn and Fiber Test
Methods. fibers to hold together by measuring the force required to slide
Current edition approved May 15, 1995. Published July 1995. Originally
fibers in a direction parallel to their length. Specific lengths of
published as D 4120 – 82. Last previous edition D 4120 – 93.
roving, sliver, or top are drafted between two pairs of rollers,
Annual Book of ASTM Standards, Vol 07.01.
with each pair moving at a different peripheral speed. The draft
Annual Book of ASTM Standards, Vol 07.02.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
D 4120
forces are recorded. Test specimens are then weighed and the 6. Apparatus and Materials
linear density calculated. Drafting tenacity, calculated as the 4
6.1 Cohesion Meter , with rollers and controls for varying
draft resisting force per unit linear density, is considered to be
drafts and rates of drafting.
a measure of the dynamic fiber cohesion. 4
6.2 Tensiometer , with accessory equipment including
measuring heads, integrator, (or computer or programmable
5. Significance and Use
calculator), and recorder for sensing, accumulating, and re-
cording drafting forces.
5.1 Test Method D 4120 for the determination of cohesion
6.3 Calibration Mass, 1 kg, NBS Class T.
in sliver, roving, or top in dynamic tests may be used for the
6.4 Tachometer, capable of measuring roll surface speed to
acceptance testing of commercial shipments but caution is
within 0.1 m/min.
advised since information on between-laboratory precision is
6.5 Balance, with sufficient capacity and sensitivity to
lacking. Comparative tests as directed in 5.1.1 may be advis-
weigh specimens to within 0.1 % of specimen mass.
able.
5.1.1 In case of a dispute arising from differences in
7. Sampling
reported test results when using Test Method D 4120 for
7.1 Lot Sampling—As a lot sample for acceptance testing,
acceptance testing of commercial shipments, the purchaser and
take at random the number of shipping containers directed in
the supplier should conduct comparative tests to determine if
the applicable material specification or other agreement be-
there is a statistical bias between their laboratories. Competent
tween the purchaser and supplier, such as an agreement to use
statistical assistance is recommended for the investigation of
Practice D 3333 or Practice D 2258. Consider shipping con-
bias. As a minimum, the two parties should take a group of test tainers to be the primary sampling units.
specimens which are as homogeneous as possible and which
NOTE 2—An adequate specification or other agreement between the
are from a lot of material of the type in question. The test
purchaser or supplier requires taking into account the variability between
specimens should then be randomly assigned in equal numbers
shipping units, between packages, ends or other laboratory sampling unit
within a shipping unit if applicable, and within specimens from a single
to each laboratory for testing. The average results from the two
package, end or other laboratory sampling unit to provide a sampling plan
laboratories should be compared using Student’s t-test and an
with a meaningful producer’s risk, consumer’s risk, acceptable quality
acceptable probability level chosen by the two parties before
level, and limiting quantity level.
the testing began. If a bias is found, either its cause must be
7.2 Laboratory Sample—As a laboratory sample for ac-
found and corrected or the purchaser and the supplier must
ceptance testing, take at random from each shipping container
agree to interpret future test results in the light of the known
in the lot sample the number of laboratory sampling units as
bias.
directed in an applicable material specification or other agree-
5.2 The cohesive forces overcome in continuous drafting of
ment between purchaser and supplier such as an agreement to
slivers, rovings, or tops are aff
...
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