I96-A09 ON-LINE MEASUREMENT OF FABRIC MECHANICAL PROPERTIES FOR PROCESS CONTROL

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I96-A09 – Page 1 of 10
I96-A09
ON-LINE MEASUREMENT OF FABRIC MECHANICAL
PROPERTIES FOR PROCESS CONTROL
Investigators:
Sabit Adanur, Yasser Gowayed, Howard Thomas (Auburn Univ.)
Tushar Ghosh (NC State Univ.)
Graduate Students:
Jing Qi, Mohamed Esad (Auburn University)
Wenshang Huang (NC State Univ.)
Refereed Journal Articles:
1. Adanur, S., and Qi, J., "Property Analysis of Denim Fabrics Made on Air-Jet
Weaving Machine, Part 2: Effects of Tension on Fabric Properties", Textile Research
Journal, Vol. 78(1), Jan. 2008, pp. 10-20.
2. Adanur, S., and Qi, J., "Property Analysis of Denim Fabrics Made on Air-Jet
Weaving Machine, Part 1: Experimental System and Tension Measurements", Textile
Research Journal, Vol. 78(1), Jan. 2008, pp. 3-9.
Abstract
Dynamic filling yarn tensions were measured on a Tsudakoma ZA203 air-jet loom using
different count cotton yarns. Fabric samples were woven under different filling tension
levels and then tested for fabric weight, thickness, permeability, dimensional stability,
abrasion resistance, drapeability, tear strength, breaking load, elongation, stiffness and
fabric wrinkle recovery. An attempt was made to correlate the filling tension and the
fabric properties. After weaving, each fabric was divided into two sections. One section
was washed and dried, and the other was left in the greige state in order to compare the
results. All fabric testing was according to ASTM and AATCC standards. Before
testing, the samples were conditioned under standard conditions (25°C, 65% RH).
Goal:
To develop principles of on-line measurement of fabric properties to improve product
quality.
Technical Background:
I96-A09 – Page 2 of 10
Mechanical properties of fabrics are altered either by design or as a side effect in most
textile processes. The ability to monitor or control fabric properties in real time is
contingent upon the availability of a system to measure these properties on-line and in
real time. This is becoming increasingly important with higher levels of automation. The
envisaged system will contribute toward manufacturing quality fabrics at lower costs, by
minimizing the need for expensive routine laboratory tests of fabrics.
The four principal fabric properties of interest to this research are tensile, bending,
compression and surface character. Tension is an important factor which affects the
productivity and quality of the fabric. Too high or too low yarn tension will cause
defaults in the fabric. Therefore, on line tension control is desirable. Several kinds of
yarn tension measurements in weaving systems are reviewed. A coordination meeting
was held in Auburn in July 96. A computerized yarn tension measurement system and
digital camera equipment were purchased.
During fabric formation, filling and warp tension is one of the leading parameters. Yarn
tension is defined as the force acting in the direction of the longitudinal axis of a yarn. It
is the quotient of tensile force and the yarn cross section derived from fineness and
density of the material. It depends on various material properties, machine type, and yarn
stress. High productivity and quality of fabric can be obtained only if the material
properties are harmoniously matched with optimal yarn tension. Yarn tension can be
divided into two types: static and dynamic. Static yarn tension which is characterized by
slow change toward lower figures. Dynamic yarn tension which consists of two
components - a basic yarn tension whose magnitude slowly changes, and a superimposed,
fluctuating yarn tension with very quick changes. These fluctuations may be of a
systematic or random character. Dynamic yarn tension occurs in the various textile
manufacturing processes, principally because a yarn or group of yarns can only be moved
from a supply position to a delivery position under the influence of a force. A minimum
force is required for this movement, which is the basic yarn tension.
During the textile processes yarn tensions may deviate from the optimal values for some
reasons. The deviations of yarn tension are possible in either direction, i.e. it may
increase or decrease. But an increase is the more significant case and is observed more
frequently than a reduction of the force acting on the yarn. If the yarn tension drops too
much below the optimum, it may result in faults in the fabric, e.g. loops in the pick.
Further drop may cause loom stoppage, e.g. shut down of a loom by the warp stopmotion. An increased yarn tension may result in the deformation of the fabric. Excessive
yarn tension leads to many faults in the fabric. If the yarn tension continues to increase,
weak yarn may break and a yarn break means stoppage of the machine. If a loom
incorporates no monitoring elements for yarn breaks, or if these do not function, faults
will appear in the fabric such as holes and runs. If the yarn tension in the process
I96-A09 – Page 3 of 10
exceeds certain limits and is stressed for extended periods in this state, the yarn will lose
its capability to recover. It is so called overextension of the yarn. It results in the
permanent change of the material's internal structure. The change alters some of yarn's
properties, so that it will react differently to mechanical or thermal influences. In
practice yarns whose internal structure has been altered by excessive tension lead to
faults as taut yarns, variant coloration, stripiness, etc. Therefore, it is very important to
avoid yarn breaks throughout the entire fabric process, and to provide the optimal tension
in every subphase.
In looms the yarn tension must be considered separately for warp and weft. In the weft
system, particularly in shuttleless systems, extremely rapid changes occur in the yarn
tension, which may lead to very high tension peaks. The warp tension has relatively slow
changes. It follows periodic changes due to the shaft movement and the reed beat-up. The
importance of the tension in the warp yarns during weaving is well recognized. Warp
tension requirement will vary depending on fabric structure and density. The tension
fluctuation is the result of shedding, beat-up, take-up, and let-off motions. Among these,
the shedding and the beat-up processes cause considerable tension loads, and the effect of
shedding is of the longest duration compared with the others. Fluctuation of warp
tension causes the yarns to be stretched, then loosened cyclically, such repeated action
damages the quality of the warp yarn. On the other hand, under the ever changing
tension, the warp will move back and forth through the reed, heddle eyes, and drop wires
many times within one deformation cycle. Therefore, finding ways to improve warp
tension is important in weaving. In weaving plain fabric, warp tension due to shedding is
usually compensated by an oscillating whip roll. Different kinds of cams have different
influence of the whip roll motion on the process of weaving on certain looms. The cam
design has little effect on fabric construction for weight, thickness, and thread count, but
the warp tension in various operating periods changes with different cams. The effect of
changing warp tension on fabric tearing strength is highly significant. Tension
fluctuation during weaving process causes the heddle to deflect in the direction of yarn
movement. Greater deflection of the heddles with certain cam could have reduced yarn
abrasion and thus compensated for the differences in warp tension fluctuation to some
extent.
Yarn tension measurement device includes a sensor (often called measuring head) to
determine the measurement magnitude, also the amplifier, tensiometer, computer, and
output units for indication, recording, and storage of the measurement values. Yarn
tension measurements can be with analog or digital methods.
Measurement or estimation of bending behavior of textile fabrics under static conditions
can be carried out by using pure bending testers (Kawabata's) or by examining shapes of
I96-A09 – Page 4 of 10
loops (Peirce's "Heart" or "Pear") or beams (FAST: Cantilever). None of these methods
can be used readily under dynamic conditions. However, types of loops can be generated
and their instantaneous shapes can be examined under dynamic conditions. These shapes
are determined primarily by the bending rigidity of the fabric in addition to few other
known parameters. The relationship between the loop-shape and these parameters can be
derived theoretically. So, in principle, once the loop-shape is determined the theoretical
relationship can be used to determine/estimate the bending rigidity of the fabric.
Results:
1. Fabric Weight
Fabric wight (oz/yd2)
Samples were weighed using ASTM D-3776 specifications. The fabric weight increased
with an increase in filling tension which resulted in the formation of heavier fabric.
When the average filling tension increased further, the filling yarn was stretched which
resulted in decrease of the fabric weight (Figure 1).
6
greige
5.5
scoured
5
4.5
4
6
6.5
7
7.5
8
8.5
Average filling tension (cN)
FIGURE 1. Fabric weight vs average
tension
2. Fabric Thickness
The samples were measured according to ASTM D1777 - 96 specifications. With the
increase of filling tension, the yarn becomes straightened and stretched. The higher the
average filling tension, the thinner the fabric (Figure 2).
Fabric thickness
(inch)
I96-A09 – Page 5 of 10
0.035
0.03
greige
0.025
scoured
0.02
0.015
6
6.5
7
7.5
8
8.5
Average filling tension (cN)
FIGURE 2. Fabric thickness vs average
filling tension
3. Fabric Air Permeability
Air permability
(ft3/min/ft2)
With increasing filling tension, fabric becomes thinner and the openings between yarns
get larger. The air permeability is generally increased (Figure 3).
250
200
greige
150
scoured
100
50
6
7
8
9
Average filling tension (cN)
FIGURE 3. Fabric permeability vs average
filling tension
4. Fabric Dimensional Stability
Filling tension introduced during weaving is one of the reasons, which makes a fabric
shrink after washing. When the stressed fabric is agitated in water, the internal tension
may be relieved. The structural readjustment takes place. The dimensional changes of
fabric were tested using AATCC test method 135-1992. Filling-way shrinkage was
measured after first and fifth washing and drying cycle (Figure 4).
Filling way
shrinkage (%)
I96-A09 – Page 6 of 10
9
8
7
6
5
4
1st wash
5th wash
0
20
40
60
80
Maximum filling tension (cN)
FIGURE 4. Fabric dimensional stability vs
maximum filling tension
5. Abrasion Resistance
Weight loss (%)
The abrasion resistance of fabric is the ability to withstand rubbing (frictional force)
applied to its surface. Fabrics with high abrasion resistance retain their physical
integrity. Fabrics with low abrasion resistance become thin and/or develop holes. They
were tested using AATCC test method 93-1989 (accelerator method).
3.5
3
2.5
2
1.5
1
greige
scoured
6
6.5
7
7.5
8
8.5
Average filling tension (cN)
FIGURE 5. Fabric abrasion resistance vs
average filling tension
6. Fabric Drapeability
Fabric drapeability is related to fabric weight, stiffness, and shear resistance. The greater
the fabric weight, the better the drapeability. The greater the fabric stiffness, the worse
the drapeability.
Drape coeffcient (%)
I96-A09 – Page 7 of 10
70
60
greige
50
scoured
40
30
6
7
8
9
Average filling tension (cN)
FIGURE 6. Fabric drapeability vs average
filling tension
7. Fabric Tear Strength
tear strength (g)
Fabric tear strength is a reflection of the individual strength of yarns. The fabric filling
way tear strength was tested according to ASTM D 1424-83 specification (Figure 7).
7000
6000
greige
5000
scoured
4000
6
7
8
9
Average filling tension (cN)
FIGURE 7. Fabric tear strength vs average
filling tension
8. Fabric Breaking (Tensile) Strength
Fabric samples were tested in wet and dry condition as specified in ASTM D 5035-90.
The filling way breaking load verses average filling tension is shown in Figure 8.
Breaking load (lb)
I96-A09 – Page 8 of 10
60
50
dry
40
wet
30
20
6
6.5
7
7.5
8
8.5
Average filling tension (cN)
FIGURE 8. Fabric breaking load vs average
filling tension
9. Fabric Elongation
Elongation (%)
Fabric filling way elongation was measured according to ASTM D 5035-90 (Figure 9).
40
30
dry
wet
20
10
6
6.5
7
7.5
8
8.5
Average filling tension (cN)
FIGURE 9. Fabric elongation vs average
filling tension
10. Fabric Stiffness
Filling flexural
rigidity (mg.cm)
Fabric stiffness was tested using ASTM D1388-64 specification. The filling way fabric
stiffness verses average filling tension is shown in Figure 10.
400
300
greige
200
scoured
100
0
6
6.5
7
7.5
8
8.5
Average filling tension (cN)
FIGURE 10. Fabric stiffness vs average
filling tension
I96-A09 – Page 9 of 10
11. Fabric Wrinkle Recovery
Wrinkle recovery
angle (degree)
The fabric wrinkle recovery was tested according to AATCC test method 66-1990
specification. The fabric filling way wrinkle recovery verses average filling tension is
shown in Figure 11.
130
greige
110
scoured
90
70
6
6.5
7
7.5
8
8.5
Average filling tension (cN)
FIGURE 11. Fabric wrinkle recovery vs
average filling tension
Summary and Conclusions:
In this study, a yarn tension measurement system was developed. Filling and warp
tensions were measured on line on an airjet weaving machine. A 3/1 left-handed twill
fabric was woven. Yarn and fabric properties were tested according to ASTM and
AATCC standard test methods. On the basis of the test results, the following conclusions
can be made:
-
the higher the yarn count, the higher the average filling tension per cycle
the higher the yarn twist multiplier, the lower the filling tension
hairiness increases filling tension
higher friction coefficient of yarn results in higher tension
increasing filling tension increases fabric air permeability
lower filling tension results in higher abrasion resistance
the higher the filling tension, the lower the tear and tensile strength
higher filling tension results in higher filling direction flexural rigidity.
Literature cited
- P. M. Latzke, Yarn tension measurements in the textile industry, Melliand
Textilberichte, September 1978, p. 714
- V. Chahal, M. H. Mohamed, Measuring filling yarn tension and its influence on
fabrics woven on a projectile weaving machine, Textile Research Journal, May 1986,
p. 324
I96-A09 – Page 10 of 10
- S. Adanur, M. H. Mohamed, Analysis of yarn tension in air-jet filling insertion,
Textile Research Journal, May 1991, p. 259
- B. V. Holcombe, R. E. Griffith & R. Postle, A study of weaving systems by means
of dynamic warp and weft tension measurement, Indian Journal of Textile Research,
March 1980, p.1
- H. Gu, Reduction of warp tension fluctuation and beat-up strip width in weaving,
Textile Research Journal, March 1984, p. 143
- D. C. Snowden, Some aspects of warp tension, Journal of Textile Institute, 1950, p.237.

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