ASTM D3108-95

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Designation: D 3108 – 95
Standard Test Method for
Coefficient of Friction, Yarn to Solid Material
This standard is issued under the fixed designation D 3108; 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 2. Referenced Documents
1.1 This test method covers the measurement of the kinetic 2.1 ASTM Standards:
frictional properties of a moving yarn in contact with a solid D 123 Terminology Relating to Textiles
material. D 1776 Practice for Conditioning Textiles for Testing
D 1907 Test Method for Yarn Number by the Skein
NOTE 1—For determining yarn-to-yarn friction, refer to Test Method
Method
D 3412.
D 2258 Practice for Sampling Yarn for Testing
1.2 This test method specifies a relative speed of 100 m/min.
D 3412 Test Method for Coefficient of Friction, Yarn to
The test method may be used at other speeds, although with a 3
Yarn
possible change in precision and coefficient of friction.
1.3 This test method covers the measurement of the coeffi-
3. Terminology
cient of kinetic friction between yarn and solid surface or
3.1 Definitions:
surfaces of constant radius in the contact area. If a yarn of
3.1.1 coeffıcient of friction, n—the ratio of the tangential
uniform value is used, comparisons of frictional properties of
force that is needed to maintain uniform relative motion
different solid materials can be made with relation to that yarn.
between two contacting surfaces to the perpendicular force
If a given solid material is used, comparisons of frictional
holding them in contact.
properties of different yarns, or yarns with different finishes,
3.1.2 friction, n—the resistance to the relative motion of one
can be made with relation to that particular solid material.
body sliding, rolling, or flowing over another body with which
1.4 This test method specifically recommends wrap angles
it is in contact.
of 3.14 and 6.28 radian (180 and 360°), but other wrap angles
3.1.2.1 Discussion—There are two frictional properties ex-
may be used, again with a possible change in precision and
hibited between any pair of surfaces: static friction and kinetic
level. The angle of wrap should not be so great, especially for
friction. Test Methods D 3108 and D 3412 both measure the
yarns having high coefficients of friction, that it causes the
coefficient of friction for kinetic friction.
output tension to exceed the yield value for the yarn being
3.1.3 kinetic friction, n—friction developed between two
tested. Also, in every case the angle of wrap should not be less
bodies in motion. (Compare Static friction.)
than 1.57 rad (90°).
3.1.4 radian, n—the plane angle between two radii of a
1.5 This test method has been applied to yarns having linear
circle which intersects the circumference of the circle making
densities ranging between 10 and 80 tex (90 and 720 denier)
an arc equal in length to the radius.
and having coefficients of friction ranging between 0.1 and 0.5
3.1.4.1 Discussion—A radian is equal to 180° divided by P
but may also be used with yarns outside these ranges of linear
and is approximately 57.3°.
densities and coefficients of friction.
3.1.5 static friction, n—friction developed between two
1.6 The values stated in SI units are to be regarded as the
touching bodies at the time one body starts to move relative to
standard. The values given in parentheses are for information
another. (Compare Kinetic friction.)
only.
3.1.6 wrap angle, n—in yarn friction testing, the cumulative
1.7 This standard does not purport to address all of the
angular contact of the test specimen against the friction-
safety concerns, if any, associated with its use. It is the
inducing device, expressed in radians.
responsibility of the user of this standard to establish appro-
3.1.7 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. Specific precau-
tionary statements are given in Section 7.
4. Summary of Test Method
4.1 A length of yarn is run at known speeds and in contact
with either single or multiple friction surfaces using a specified
This test method is under the jurisdiction of ASTM Committee D-13 on Textiles
and is the direct responsibility of Subcommittee D13.58 on Yarn Test Methods,
General.
Current edition approved May 15, 1995. Published July 1995. Originally Annual Book of ASTM Standards, Vol 07.01.
published as D3108 – 72T. Last previous edition D3108 – 89. Annual Book of ASTM Standards, Vol 07.02.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
D 3108
wrap angle. (See Fig. 1.) The yarn input and output tensions are performance properties of yarns and subsequently of products
measured, and the coefficient of friction is calculated by means made from them. As a consequence, frictional properties are of
of Amontons’ law (see 11.4). Alternatively, apparatus is used in interest in research, control, and product design.
which the ratio of output tension to input tension is measured 5.3 It is stressed that there is no coefficient of friction for a
allowing the coefficient of friction to be indicated directly. single body such as a yarn or a surface. A coefficient of friction
measures the interaction between two bodies or elements such
5. Significance and Use
as a yarn running over a surface.
5.4 Although this method lays down standardized condi-
5.1 Test Method D 3108 for the determination of kinetic
tions of test, nonstandard conditions may be used for research
friction between yarn and solid materials may be used for the
or diagnosis but should be reported as such.
acceptance testing of commercial shipments of yarn, but
5.5 This method covers determination of the mean friction
caution is advised since between laboratory precision is known
over a specified length of yarn.
to be poor. Comparative tests as directed in 5.1.1 may be
5.6 Additional information has been reported in the litera-
advisable.
, ,
4 5 6
ture.
5.1.1 In case of a dispute arising from differences in
reported test results when using Test Method D 3108 for
6. Apparatus
acceptance testing of commercial shipments, the purchaser and
6.1 Friction Testing Apparatus (Indirect) (Fig. 2)—
the supplier should conduct comparative tests to determine if
Apparatus in which the input tension is measured or controlled
there is a statistical bias between their laboratories. Competent
to a set value, the output tension is measured, and the
statistical assistance is recommended for the investigation of
coefficient of friction is calculated within or outside the
bias. As a minimum, the two parties should take a group of test
apparatus.
specimens which are as homogeneous as possible and which
6.1.1 Yarn Tension Input Control—A means of controlling
are from a lot of material of the type in question. The test
the yarn input tension to the nearest 61mN(60.1 gf). A
specimens should then be randomly assigned in equal numbers
demand-fed apparatus with a fixed weight is suitable.
to each laboratory for testing. The average results from the two
6.1.2 Yarn Input Tension Measurement—The yarn input
laboratories should be compared using Student’s t-test for
tension is measured to within 61mN(60.1 gf) using a
unpaired data and an acceptable probability level chosen by the
suitable tension gage producing an electrical signal. The signal
two parties before the testing is begun. If a bias is found, either
is recorded as mN (gf) or is used in combination with the yarn
its cause must be found and corrected, or the purchaser and the
output tension measurement to calculate the coefficient of
supplier must agree to interpret future test results with consid-
friction.
eration to the known bias.
5.2 The frictional properties of textile yarns and of machin-
Olsen, J.S., “Frictional Behaviour of Textile Yarns,” Textile Research Journal,
ery components such as yarn guides are of general interest and
Vol 39 No 1, 1969, pp 31–37.
have many applications. Because the frictional properties of
Lyne, D.G., “Dynamic Friction Between Cellulose Acetate Yarn and a Metal
Cylinder,” Journal of the Textile Institute, Vol 46, 1955, p 112.
yarns will affect the performance and life of yarn guides,
Rubenstein, C., “Review of the Factors Influencing the Friction of Fibres, Yarns
sewing and knitting needles, and other contact surfaces, the
and Fabrics,” “Wear” Vol 2, 1958–59, p 296.
modifying effects of surface finishes and lubricants are of 7
Equipment meeting these requirements may be commercially obtained from
special interest. Frictional properties also affect the quality and Lawson Hemphill (Sales) Inc., PO Drawer 6388, Spartanburg, SC 29304.
FIG. 1 Schematic Diagram of Angle of Wrap
D 3108
FIG. 2 Schematic Diagram of Typical Yarn Friction Measuring Apparatus, Indirect Type
6.1.3 Yarn Output Tension Measurement—The yarn output close control of input tension is not usually required. However,
tension is measured to within 61mN(60.1 gf) using a because the absolute level of input tension can affect the
suitable tension gage producing an electrical signal. The signal measured coefficient of friction for certain yarns, particularly
is recorded as mN (gf) or is used in combination with the yarn low-twist yarns, the general level of input tension should be
input tension measurement to calculate the coefficient of preset, for example with a dead weight disk tensioner.
friction. A suitable chart recorder may be used. 6.2.2 Coeffıcient of Friction Indicator—The nature of this
6.2 Friction Testing Apparatus (Direct) (Fig. 3)—Apparatus will depend on the instrument being used. Typically, a pointer
in which the ratio of output to input tensions is established or a chart recorder pen is displaced by the movement of the
directly and the coefficient of friction indicated on a scale or components that bring the system into balance and the product
display. The comparison may be mechanical. of the input tension and the distance from the axis equals the
6.2.1 Yarn Tension Input Control—Since this type of appa- product of the output tension and the distance from the axis
ratus automatically derives the ratio of output-to-input-tension, (see Fig. 3).
FIG. 3 Schematic Diagram of Typical Yarn Friction Measuring Apparatus, Direct Type
D 3108
6.3 Friction Surface, may be changeable on some equip- 9.2 The strand to be tested must have a uniform moisture
ment. content along its length. Atmospheric conditions must there-
6.3.1 Standard Friction Surface—Friction surfaces having a fore be stable and the strand must be in equilibrium with the
diameter of 0.5 in. (12.7 mm) and a chrome surface of 4 to 6 prevailing atmosphere. To satisfy this condition, testing should
μm roughness. The use of one, two, or three pins in sequence be carried out after thorough conditioning in the standard
has been found satisfactory although there may be a difference atmosphere for testing textiles.
in the results (theoretically only the total angle of wrap and not 9.3 Preconditioning—Precondition packages of yarn for at
the number of pins should affect the results). (See 12.3.4). least3hinan atmosphere with a relative humidity between 5
6.3.2 Other Friction Surfaces—Unless the apparatus has a and 25 % and a temperature not exceeding 50°C (120°F).
friction surface that cannot be altered, friction surfaces of 9.4 Conditioning—Condition the preconditioned packages
different materials, sizes, and surface finish may be used but of yarn in the standard atmosphere for testing textiles (relative
must be specified in the report (see section 11.3.4). humidity 65 6 2 % and temperature 21 6 1°C (70 6 2°F)) in
6.4 Drive System, consisting of a controlled speed yarn moving air until it has reached moisture equilibrium for testing
transporting device with appropriate controls to record and as directed in Practice D 1776.
adjust the linear or throughput speed. Generally, a speed of less
10. Procedure
than 300 m/min has been found preferable. The yarn transport-
10.1 Test all specimens in the standard atmosphere for
ing device should be constructed to eliminate yarn slippage by
testing textiles which is 21 6 1°C (70 6 2°F) and 656 2%
the use of high-friction surface.
relative humidity.
6.5 Cotton Yarn For Cleaning—A thoroughly scoured cot-
10.2 Prior to each test, thoroughly clean the friction ele-
ton yarn that is highly absorbent (see section 10.2.2 and Annex
ments, input rolls, and any other surfaces with which the yarn
A1).
comes in contact up to and including the friction element, using
6.6 Solvent—See 9.2.
one of the following:
7. Hazard 10.2.1 A solvent which contains no trace oils, or
7.1 Refer to the manufacturer’s material safety data sheet
NOTE 3—Precaution: If solvent is used, appropriate health and safety
for information on storage, handling, use, and disposal of
precautions must be taken. (See Section on Hazards)
chemicals used in this test method.
10.2.2 A thoroughly scoured cotton yarn that is highly
absorbent used as a cleaning yarn. See Annex A1 for details.
8. Sampling
10.3 Check the surface properties of the friction elements
8.1 Lot Sample—As a lot sample for acceptance testing,
for wear, gouging, or channeling. Some textile yarns, specifi-
take at random the number of shipping units directed in an
cally glass, stainless steel, delustered yarns, and other high-
applicable material specification or other agreement between
modulus yarns, are known to create excessive wear on most
the purchaser and the supplier, such as an agreement to use
guide surface materials, including chromium. Check for evi-
Practice D 2258. Consider shipping cases or other shipping
dence of surface wear periodically by the use of control yarns,
units to be the primary sampling units.
microscopic examination, or other forms of examining or
NOTE 2—An adequate specification or other agreement between the
measuring surface uniformity. Replace or refurbish friction
purchaser and the supplier requires taking into account the variability
elements which show signs of wear, gouging, or channeling.
between shipping units, between packages or ends within a shipping unit,
10.4 Take care not to contaminate the yarn test specimen or
and between specimens from a single package so as to provide a sampling
the cleaned yarn-contacting surfaces of the apparatus.
plan with a meaningful producer’s risk, consumer’s risk, acceptable
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