USTER® TESTER 5-S800
APPLICATION REPORT
The measurement of the
yarn diameter, density
and shape of yarns
THE YARN INSPECTION SYSTEM
S. Dönmez Kretzschmar, R. Furter
Version 1.1
September 2009
SE 629
THE YARN INSPECTION SYSTEM
Copyright 2009 by Uster Technologies AG
All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, translated or transmitted in any form or by any means, electronically, mechanically, photocopying, recording or otherwise, without the prior permission in writing of the copyright owner.
veronesi\TT\Schulung_Dokumente\Off-Line\UsterTester5 \SE-629_The measurement of the yarn diameter, density and shape of yarns
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USTER® TESTER 5-S800
THE YARN INSPECTION SYSTEM
Contents
1
Introduction ................................................................................ 5
1.1
Measuring principle ...................................................................... 8
1.2
Measurement of the diameter variation........................................ 8
1.3
Numerical values of the optical sensor OM.................................. 8
2
The quality parameters of the OM sensor.............................. 11
2.1
Diameter..................................................................................... 11
2.2
Density ....................................................................................... 12
2.3
Shape......................................................................................... 14
2.4
The CV of the Fine Structure ..................................................... 16
3
Results of the practical trials .................................................. 16
3.1
Comparison of different spinning systems ................................. 16
3.1.1
Comparison of Ne 20, 100% cotton yarns, produced by
5 different spinning systems....................................................... 20
3.1.2
Comparison of Ne 30, 100% cotton yarns, produced by
5 different spinning systems....................................................... 22
3.1.3
Comparison of mass variation CVm and hairiness .................... 25
3.1.4
Comparison of imperfections ..................................................... 26
3.1.5
Comparison of diameter 2DØ, shape and density ..................... 27
3.1.6
Comparison of three types of diameter variations and the
surface structure ........................................................................ 29
3.1.7
Comparison of tenacity and elongation ...................................... 31
3.2
Variation of the effective mean yarn diameter............................ 33
4
Additional information gained by combination of optoelectronic and capacitive sensors.......................................... 35
5
Conclusion................................................................................ 37
6
Literature................................................................................... 38
USTER® TESTER 5-S800
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THE YARN INSPECTION SYSTEM
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USTER® TESTER 5-S800
THE YARN INSPECTION SYSTEM
1
Introduction
The USTER® TESTER 5 is a modular laboratory system. It can be
equipped with an optical sensor which can measure the yarn diameter, the
yarn density and the yarn roundness. In addition, it can determine the “optical” yarn evenness based on a 0.3 mm and 8 mm measuring zone. With
the measuring zone of 0.3 mm short-term diameter variations can be measured.
The USTER® TESTER 5 uses two parallel light beams creating double illumination on the yarn to measure these parameters optically in a twodimensional environment at a high degree of precision.
Unlike yarn hairiness, most spinners are not familiar with these measurements. The importance of these measurements stems directly from the
evolutionary development of spun yarn and the need for associating the
yarn with the fabric quality that it can produce.
As shown in Fig. 1; different yarn types exhibit different structural features.
In addition, within the same yarn type, the surface structure can be modified to serve specific applications (e.g. different navels in rotor spinning). It
is important, therefore, that the spinner establishes a surface identity of the
yarn produced as it is often the case that the spinner is challenged by a
fabric producer to produce yarns that result in certain surface features in
the fabric.
Structure of a ring-spun yarn
Structure of an OE rotor yarn
USTER® TESTER 5-S800
Structure of a compact yarn
Structure of Vortex yarn
Fig. 1
Yarn surface structure
®
measurements by USTER
TESTER 5
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THE YARN INSPECTION SYSTEM
Table 1 shows relationships which are important for the understanding of
optical sensors:
USTER® TESTER 5 Optical sensor OM
The yarn diameter depends on the number of fibers in the cross-section, the
fiber fineness, the density, the twist and the surface structure.
The variation of the diameter of the yarn at 8 mm is strongly affected by the surface fiber arrangement and the density.
The variation of the diameter of the yarn at 0.3 mm is affected by the short surface faults (neps), the seed coat fragments, the wrapped fibers, etc.
Table 1
®
USTER TESTER 5
Optical sensor OM
The shape (roundness) of the yarn depends on the spinning preparation, the
spinning system and the yarn type.
The difference between these surface parameters and the traditional appearance parameters (i.e. CVm, thick places, thin places, and neps) lies in
the fact that they are measured optically, not by capacitive means. This
allows two advantages:

the recognition of quality problems which cannot be found with capacitive sensors because the mass of the yarn is not affected (e.g. change
of the twist due to slow spindles)

more detailed evaluation of the yarn surface structure and shape

the possibility to evaluate specialty yarns (e.g. fancy yarns which do not
change mass or yarns containing conductive fibers for which capacitive
means are not suitable)
In today’s market, reliable information of materials and products is the key
to succeed in meeting customer demands and in achieving profitable process. When information is obtained inclusively and efficiently, necessary
improvements can be made and preventive or corrective actions can be
taken on timely fashion. This solidifies customer’s confidence in your product and your organization. Surface structure parameters directly reflect the
fabric appearance and surface properties.
In many situations, fabric problems such as scattered, but noticeable by the
human eye, shade variations can not be predicted using traditional capacitive measures only. Fig. 2 shows one example of this type of variation. In
diagnosing the unraveled yarn from this fabric, the cause of spotted shade
concentration was diagnosed as a result of high variation in diameter between very small segments in the yarn.
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USTER® TESTER 5-S800
THE YARN INSPECTION SYSTEM
Fabric rejected due
to shaded spots
Small diameter segment
Large diameter segment
Medium diameter segment
different very small segments (0,1 to 0,5 mm) of the same yarn
with different yarn diameters and surface fiber arrangements
Fig. 2
Example of small variations
that can be detected
through the measurement of
diameter variation and yarn
®
shape by the USTER
TESTER 5
Testing yarn diameter is also critical for estimating some of the critical parameters of woven and knit fabric structures i.e. cover factor and stitch
length. Fig. 3 shows examples of this type of calculations. Traditionally,
these estimations were performed using crude estimation of yarn diameter.
With the availability of this measurement through the USTER® TESTER 5,
better estimates of fabric structure can be achieved.
Woven fabric
filling
dfilling
It is important to point out that two yarns of the same count made from the
same fibers but using two different spinning systems (e.g. ring and rotor
spinning) may not have the same yarn diameter. This is a direct result of
the difference in the packing density of the two yarns.
Fabric cover factor:
Warpwise cover factor = CFwarp = dwarp/warp
dwarp
warp
Plain weave
dfilling = filling yarn diameter
filling = filling yarn pitch
dwarp = warp yarn diameter
warp = warp yarn pitch
Knit fabric
Stitch length:
c = the course spacing [C=1/c = courses/inch]
Knit fabric
Fig. 3
w = the wale spacing [W=1/w = wales/inch]
d = yarn diameter
Utilization of yarn diameter for estimating fabric structural parameters
USTER® TESTER 5-S800
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THE YARN INSPECTION SYSTEM
1.1 Measuring principle
The optical measuring system used for this purpose is shown in Fig. 4. The
yarn moves through an optical field consisting of 2 parallel light beams
which illuminate the yarn from two sides. The angle of the two light beams
is 90 degrees. With this method it is possible to determine accurate test
results with respect to diameter, diameter variation, roundness and surface
structure of yarns.
Receiver 1
Receiver 2
Yarn
Light source 2
Light source 1
Mirror
Mirror
Fig. 4
Sensor OM
Since a capacitive sensor is not able to measure the evenness of special
yarns containing electrically conductive material such a metallic fibers, etc.,
carbon fibers, the optical sensor can be used for this purpose.
1.2 Measurement of the diameter variation
Fig. 5 shows the variation of the diameter of a core yarn, Nec 34.
Fig. 5
Diameter variations of a
core yarn
The measurement in Fig. 5 shows a significant variation of the yarn diameter.
1.3 Numerical values of the optical sensor OM
Table 2 shows the quality characteristics which can be determined with this
sensor, Ne 30, 100% cotton, ring-spun, combed yarn, 10 bobbins.
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USTER® TESTER 5-S800
THE YARN INSPECTION SYSTEM
No.
2D
CV2D
CV2D
CV FS
CV1D
Shape
D
mm
8mm
0.3mm
1
0.186
10.12
13.14
8.39
16.01
0.80
0.54
2
0.188
10.51
13.33
8.19
15.62
0.82
0.53
3
0.190
10.31
13.23
8.29
15.74
0.81
0.53
4
0.184
10.13
13.02
8.18
15.69
0.81
0.56
5
0.188
10.40
13.24
8.19
15.54
0.82
0.53
6
0.190
10.39
13.35
8.38
15.78
0.81
0.53
7
0.188
10.32
13.28
8.36
15.82
0.81
0.54
8
0.188
10.19
13.11
8.25
15.75
0.81
0.54
9
0.189
10.45
13.30
8.23
15.91
0.80
0.54
10
0.183
10.19
13.09
8.20
16.07
0.79
0.55
Mean
0.187
10.30
13.21
8.27
15.79
0.81
0.54
g/cm3
0.3mm
CV
1.2
1.3
0.9
1.0
1.0
0.9
1.7
Q95
0.002
0.10
0.08
0.06
0.12
0.01
0.01
Max
0.190
10.51
13.35
8.39
16.07
0.82
0.56
Min
0.183
10.12
13.02
8.18
15.54
0.79
0.53
64
34
USP 07
Quality
parameter
57
Table 2
Results obtained with the
optical sensor OM
Definition of the terms
2D Ø
Diameter of the yarn based on a two-dimensional sensor
CV2D 8mm
Evenness based on diameter measurement, measuring zone 8 mm,
two-dimensional sensor
CV2D 0.3mm
Evenness based on diameter measurement, measuring zone 0,3 mm,
two-dimensional sensor
CV1D 0.3mm
Evenness based on diameter measurement, measuring zone 0,3 mm,
one-dimensional sensor
CV FS
Surface structure of the yarn
Shape
Roundness of the yarn according to the definition, section 2.3.
D
Density of the yarn in g/cm3
Table 3
Definition of quality
parameters
In Table 3, beside the diameter and shape values we can also see three
different CV values. CV1D 0.3mm can be used for comparative purposes,
for example comparison with results from other instrument manufacturer’s
optical evenness testers which only function one-dimensionally. CV2D
0.3mm is used as an indicator of very short variations of the diameter along
the yarn. With the cut length of only 0.3 mm it is possible to measure the
variation down to the length where the roughness of the yarn becomes apparent. It can help predict what the graininess of the end product would be,
especially with knitwear.
The quality parameter CV2D 8mm is used as a measure of optical evenness; its application is similar to the CV for mass. In certain end products,
especially knitwear, the diameter variation CV2D of the yarn can predict the
fabric’s appearance, regarding irregularity of "cloudiness” in a different way
than the capacitive sensor.
USTER® TESTER 5-S800
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THE YARN INSPECTION SYSTEM
Fig. 6 shows a variance-length curve and the values of a Ne 24, 100% cotton, ring-spun, combed yarn with a measuring zone of 8 and 0.3 mm.
%
CV
CV 2D 0,3 mm
20
10
CV 2D 8 mm
5
3
Fig. 6
Variance-length curve,
CV 2D 0.3 mm = 18.45%
CV 2D 8 mm = 11.54%
2
1
0,01
0,1
1
10
100 cm
Cut length
As the “cut length” for CV 2D 0.3 mm is much shorter than for CV 2D 8 mm,
the value is considerably higher, because short-term variations affect the
result considerably.
For the ring-spun yarn, Fig. 7, the value for a measuring zone of 8 mm is
10.30%, for a measuring zone of 0.3 mm the value is 13.21%. Short yarn
faults such as fiber neps, seed coat fragments, trash particles or wrapped
fibers can substantially affect the diameter variation with a measuring zone
of only 0.3 mm.
Table 4 shows the results of the 10 bobbins taken from Table 2. Fig. 7
shows the interpretation of this value by means of the USTER® STATISTICS.
Nr
CV 2D
0.3mm
1
13.14
2
13.33
3
13.23
4
13.02
5
13.24
6
13.35
7
13.28
8
13.11
9
13.30
10
13.09
Mean
13.21
CV
0.9
Q95
0.08
USP 07
57
Table 4
10 (40)
Fig. 7
USTER® STATISTICS 2007,combed, ring-spun yarn, CV 2D 0,3 mm
USTER® TESTER 5-S800
THE YARN INSPECTION SYSTEM
The mean value of the coefficient of variation CV2D 0.3mm equals 13.21. If
this value is entered into the USTER® STATISTICS, the dot lies on the
57%-line of the USTER® STATISTICS (Fig. 7).
2
The quality parameters of the OM sensor
2.1
Diameter
The diameter of the yarn is determined by the number of fibers in the crosssection, the fiber fineness and the twist. If the number of fibers is too low or
too high or the twist deviates from the nominal value, the fault can be noticed by a comparison of the diameter of several bobbins. The diameter is
used as a comparative value. Yarns of the same count, material, spinning
system and twist multiplier should always have the same average diameter.
The yarn diameter, as well as the hairiness, also have an effect on the
cover factor of a textile fabric and are partly responsible for the weft insertion characteristics (air friendliness) on air-jet weaving machines.
Fig. 8 shows the tendency of every yarn spinning system separately. Here
we can see that when the yarn gets finer, the diameter values decrease.
The variation of the average yarn diameter from sample to sample for a
given yarn count is insignificant. The highest variation can be noticed for
OE rotor yarn.
0.8
0.7
2DØ (mm)
0.6
0.5
0.4
0.3
0.2
0.1
0.0
30
60
24
30
36
41
30
40
50
65
100
7
12
16
20
Combed
35
24
33
16
30
Carded
Yarn Count (Ne)
Compact
Ring-combed (knitting)
Ring-combed (weaving)
OE-rotor
Ring-carded (knitting)
Ring-carded (weaving)
Fig. 8
Diameter of the selected
790 yarns according to different yarn spinning techniques
The graph in Fig. 9 shows the relationship between the diameter and the
count. We can see that when the yarn count (Ne) increases, the diameter
values decrease.
USTER® TESTER 5-S800
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THE YARN INSPECTION SYSTEM
(mm)
Diameter
0,6
0,5
0,4
0,3
0,2
0,1
0
5
120
10
60
20
30
40
15
60
10
80
7,5
100
6
120
5
tex
Ne
Fig. 9
Diameter versus Yarn
Count.
Yarn: ring-spun, carded and
combed
The graph in Fig. 10 shows the relationship between the diameter and the
density values. When the yarn gets finer, the diameter values decrease, but
the density values increase because the twist per meter also increases.
2.2
Density
3
(g/cm )
Density
0,7
0,6
0,5
0,4
5
120
10
60
15
40
20
30
25
24
30
20
Fig. 10
Density versus Yarn Count.
Yarn: ring-spun, combed,
for woven fabrics
tex
Ne
Density is an absolute measure for a yarn’s compactness. Yarn density is
strongly dependent on the degree of twist given to a yarn. Therefore, production problems such as slow spindles can be detected by evaluating this
parameter. As we mentioned before, the density of a yarn provides an indication of the yarn twist and of the yarn construction.
Low density is equivalent to a low twist, whereas high density indicates a
yarn with a higher twist and a higher compactness respectively. Regarding
the density, it must be noted that, with the same yarn count, it is directly
dependent on the yarn diameter, which, as already mentioned, again depends on the yarn twist per meter.
The indicated density values in Fig. 10 are mean values of the individual
samples. There is also a relationship between the density and the fabric
handle.
Since fine ring-spun yarns have a higher twist than coarse yarns, the density of fine yarns is always higher than coarse yarns.
12 (40)
USTER® TESTER 5-S800
THE YARN INSPECTION SYSTEM
Mean density (Table 2, column 7) of the yarn over the entire test length of
the yarn (in g/cm³), calculated with the nominal yarn count:
 
π
d = Yarn diameter (cm)
 = Length of yarn (cm)
︶
︶


m
c
/
g
t
n
u
o
c
n
r
a
Y
︵
3
m
c
/
g

m
D = Yarn density (g/cm3)

π
2
d


m = Mass of yarn (g)

5
0
1
x
e
t
4
D

︵
 
3
m
c
/
g
m
4


g
4
2
d
D

D
π
2
d
m


︵
︶ = 10 -5 tex
Example
Weaving yarn: Cotton, combed, Ne 40 (15 tex) / d = 0,18 mm (measured
with the USTER® TESTER 4 or 5, sensor OM)
D
4  1,5  10 4
4
4
5
5
15
10
tex
10
 0,59 g/cm 3






3,24  10 4  3,14
0,018 2  π
d2  π
D is an absolute value for the compactness of yarn. The yarn density is
strongly dependent on the degree of twist applied on a yarn. Therefore,
production problems such as slow spindles can be detected by evaluating
this parameter. Since a deviation from nominal twist has no effect on the
mass variation, the fault cannot be recognized by capacitive sensors.
Fig. 11 shows the tendency of every yarn spinning system separately.
When the yarn gets finer, the density values increase because the twist
also increases. Generally, carded yarns have lower density values than the
combed yarns. The descending order of the density values according to
yarn spinning methods is: Compact, ring combed (weaving), ring combed
(knitting), ring carded (weaving), ring carded (knitting) and OE rotor yarns.
1.0
0.9
0.8
Density (g/cm3)
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
30
60
24
30
36
41
30
40
50
65
100
7
12
16
20
35
Combed
24
33
16
30
Carded
Yarn Count (Ne)
Compact
Ring-combed (knitting)
Ring-combed (weaving)
USTER® TESTER 5-S800
OE-rotor
Ring-carded (knitting)
Ring-carded (weaving)
Fig. 11
Density values of the selected 790 yarns according
to different yarn spinning
techniques
13 (40)
THE YARN INSPECTION SYSTEM
Table 5 shows the results of a sample of 10 bobbins, Ne 30, 100% cotton,
ring-spun, combed, knitting yarn. Fig. 12 shows the interpretation of this
value by means of the USTER® STATISTICS.
Nr
D
g/cm
1
0.54
2
0.53
3
0.53
4
0.56
5
0.53
6
0.53
7
0.54
8
0.54
9
0.54
10
0.55
Mean
0.54
CV
1.7
Q95
0.01
USP 07
21
3
Table 5
Fig. 12
USTER® STATISTICS 2007, combed, ring-spun yarn, for knitted fabrics, density
The mean value of the density equals 0.54. If this value is entered into the
USTER® STATISTICS (Fig. 12), it is equivalent to 21%-line of the
USTER® STATISTICS.
2.3
Shape
Shape is another factor which can influence the appearance of the yarn’s
end product. In the initial testing of yarns (100% cotton) of different yarn
counts and spinning methods, it became apparent that the different spinning methods have an immediate effect on the roundness (shape) and the
density of yarns. The shape or the roundness of the yarn can considerably
affect the appearance of a fabric. Therefore, the roundness also belongs to
the quality characteristics of yarns. Fig. 13 shows the calculation of the
roundness:
a
Shape = b
a
b
14 (40)
The shape is a factor which indicates the average yarn roundness over the entire test length
of the yarn. The value corresponds to the ratio of the short
to the long main axis of an ellipse (1 = circular).
Fig. 13
Definition of shape
USTER® TESTER 5-S800
THE YARN INSPECTION SYSTEM
Table 6 shows the experience values of the shape and the tendency of
every yarn spinning system separately. When the yarn gets finer, the shape
values do not change .. Ring-carded (weaving), Ring-carded (knitting), Ring
combed (knitting), Ring combed (weaving), and compact yarns have similar
shape values; however OE-rotor yarns have lower shape values than the
others.
Spinning System
Shape
Compact
0.80 – 0.88
Ring, combed, knitting
0.79 – 0.88
Ring, combed, weaving
0.80 – 0.89
Ring, carded, knitting
0.79 – 0.85
Ring, carded, weaving
0.79 – 0.86
OE rotor
0.67 – 0.80
Table 6
The experience values of
the shape
Table 7 shows the results of a sample of 10 bobbins, Ne 30, 100% cotton,
ring-spun, combed yarn for knitted fabrics. Fig. 14 shows the interpretation
of this value by means of the USTER® STATISTICS.
Nr
Shape
1
0.80
2
0.82
3
0.81
4
0.81
5
0.82
6
0.81
7
0.81
8
0.81
9
0.80
10
0.79
Mean
0.81
CV
0.9
Q95
0.01
USP 07
57
Table 7
Fig. 14
USTER® STATISTICS 2007, combed, ring-spun yarn, for knitted fabrics, shape
The mean value of the shape equals 0.81. This is equivalent to 57%-line
of the USTER® STATISTICS. (Fig. 14, the dot).
USTER® TESTER 5-S800
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THE YARN INSPECTION SYSTEM
2.4
The CV of the Fine Structure
The CV of the Fine Structure is the specific indicator for a yarn’s roughness. It describes the short-term variation of a yarn. Only the irregularity
increase between 0.3 mm and 8 mm cut length is taken into account. It is a
comparison between the diameter variation with a measuring zone of eight
millimeters and a measuring zone of 0,3 mm. In our example, the mean
value of the CV of the Fine Structure equals 8.27%.
3
Results of the practical trials
3.1
Comparison of different spinning systems
As it was mentioned before, in order to obtain additional information about
the yarns, Uster Technologies recommends combining both measurement
principles; capacitive and optical. In order to show how these measurement
principles can be used together we have taken two groups of yarns. In our
practical trials, first we have tested Ne 20, 100% cotton yarns produced
with five different spinning systems. In our second practical trial, we have
tested Ne 30 yarns, which were also spun according to different spinning
systems. Except MJS air-jet yarn (50% Cotton/ 50 % Modal), they are all
produced from 100% cotton. Fig. 20 shows a comparison of the diagrams
of Ne 20, 100% cotton yarns and Fig. 22 shows a comparison of the diagrams of Ne 30, 100% cotton yarns. Fig. 21 and Fig. 23 show comparisons
of the spectrograms of these two groups of yarns.
As we mentioned before, different yarn types exhibit different structural
features. In our trials, carded and combed ring yarns, OE-rotor yarns, air-jet
yarns (air-jet and vortex) and compact yarns are tested.
Ring spinning or conventional spinning is a well-known spinning technique.
Compact yarn spinning system was developed by means of modifications
to the conventional ring spinning process with the aim of altering the geometry of the spinning triangle. This is done to improve the structure of the
ring-spun yarn by more effective binding-in of surface fibers into the body of
the yarn. The result is reduced hairiness, higher strength, improved evenness and reduced imperfections [1]. Fig. 15 shows that the compact spinning system avoids the formation of the spinning triangle. This results in a
minimum number of protruding fibers.
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USTER® TESTER 5-S800
THE YARN INSPECTION SYSTEM
Fig. 15
Spinning triangle of compact and ring yarn [1]
With the OE spinning technique, there is an open end, which can be rotated
continuously in flow around a core. Fibers which are outside the core can
be rearranged and trapped in the structure in order to give different yarn
characteristics [2].
Fig. 16
OE-rotor spinning system
[2]
In air-jet spinning, we are talking about ”fasciated” (wrapped) yarn principle.
Lawrence [1] defined wrap spinning as a process whereby a drafted ribbon
of parallel fibers, which consists of the bulk of the spun yarn, is wrapped by
either surface fibers protruding from the ribbon to impart coherence and
strength to the resulting yarn. There are many techniques of surface fiber
wrapping like Murata MJS, MTS, RJS and Vortex, Suessen PLYfil, Toyoda
TYS, Fehrer DREF3, Toray AJS, etc. [3].
USTER® TESTER 5-S800
17 (40)
THE YARN INSPECTION SYSTEM
Fig. 17
Twist triangle zone of air-jet
spinning [2].
Here we have taken two example: the first one is Murata Jet Spinning
(MJS) which is a fasciated (wrapping) yarn spinning. It is used to process
100% polyester and polyester-cotton or polyester-viscose blends. The spinning system consists of a 3-over-3 high speed roller drafting unit, two compressed-air twisting jets arranged in tandem, a pair of take-up rollers and a
package build unit [1].
Fig. 18
Murata MJS Air-jet spinning
system [1]
The second example of yarn is a Murata Vortex yarn. Murata Vortex system is a single air-jet spinning system. When we compare with the tandem
jet system, it incorporates a modified jet inlet.
18 (40)
USTER® TESTER 5-S800
THE YARN INSPECTION SYSTEM
In this system, the partial blocking of the twist flow may occur above the jet
nozzles to enable the formation of an extended spinning triangle and
thereby increase the generation of “edge fibers”. The lower degree of
wrapping has the advantage of producing softly wrapped yarns [1,2]. With
this system, it is possible to spin 100% cotton yarns.
Fig. 19
Murata Vortex spinning system [1]
The optical sensor OM of the USTER® TESTERS 4 and 5 is able to determine the quality of the new yarn formation systems in more detail.
Fig. 20 to 24 demonstrate a comparison of the test results of two yarn
counts Ne20 and Ne30, 100% cotton, (exception: MJS 50% cotton, 50%
Modal). Five different spinning systems are compared.
The graphical results under 3.1.1 and 3.1.2 demonstrate the following:

The comparison of the yarn diagrams of various spinning systems express the characteristics of the yarns:
- High mass variation of carded ring-spun yarn, regular mass variation of combed ring, air-jet, OE rotor and compact yarn.
- High hairiness of carded ring-spun yarns, low hairiness of combed
or compact yarns.
- High variation of surface structure (diagram variation) in the case of
carded ring-spun yarn, low variation for air-jet yarn, etc.

The capacitive sensor (mass variation) can extremely well detect “drafting waves” as a result of short fibers in carded ring spun yarns  see
spectrogram of carded ring-spun yarn under 3.1.2 at around 8 cm.

The capacitive sensor (mass variation) can easily detect drafting problems of the drawframe  see spectrogram of carded ring-spun yarn
under 3.1.1 and 3.1.2 at around 20 m.

The optical sensor (diameter variation) can detect short term variations
in the area of 0,5 cm to 2 cm.
USTER® TESTER 5-S800
19 (40)
THE YARN INSPECTION SYSTEM
3.1.1
Comparison of Ne 20, 100% cotton yarns, produced by 5 different spinning systems
Diagram
Ring-Yarn Carded
Ring-Yarn Combed
Mass variation
Hairiness
variation
Diameter
variation
Fig. 20
Diagrams of mass, hairiness and yarn diameter (Ne 20, 100% cotton yarns)
Spectrogram
Ring-Yarn Carded
Ring-Yarn Combed
Mass variation
Hairiness
variation
Diameter
variation
Fig. 21
20 (40)
Spectrograms of mass, hairiness and yarn diameter (Ne 20, 100% cotton yarns)
USTER® TESTER 5-S800
THE YARN INSPECTION SYSTEM
OE-yarn
Air-jet (Vortex)
Compact (Rotorcraft)
OE-yarn
Air-jet (Vortex)
Compact (Rotorcraft)
USTER® TESTER 5-S800
21 (40)
THE YARN INSPECTION SYSTEM
3.1.2
Comparison of Ne 30, 100% cotton yarns, produced by 5 different spinning systems
Diagram
Ring-Yarn Carded
Ring-Yarn Combed
Mass variation
Hairiness
variation
Diameter
variation
Fig. 22
Diagrams of mass, hairiness and yarn diameter (Ne 30, 100% cotton yarns)
Spectrogram
Ring-Yarn Carded
Ring-Yarn Combed
Mass variation
Hairiness
variation
Diameter
variation
Fig. 23
22 (40)
Spectrograms of mass, hairiness and yarn diameter (Ne 30, 100% cotton yarns )
USTER® TESTER 5-S800
THE YARN INSPECTION SYSTEM
OE-yarn
Air-jet (MJS)
(50% CO / 50% Modal)
Compact (K44)
OE-yarn
Air-jet (MJS)
(50% CO / 50% Modal)
Compact (K44)
USTER® TESTER 5-S800
23 (40)
THE YARN INSPECTION SYSTEM
Table 8 shows the quality characteristics of these yarns.
Ne 20, 100% cotton yarn
®
Neps +200%
H
2DØ mm
CV1D
0.3 mm
CVFS
Shape
D
g/cm3
Elongation
Tenacity
Elongation
Tenacity
172
5.9
0.28
10.5 14.5
17.5
10.0
0.79
0.49
5.0
16.1
4.8
18.8
combed
10.6
6
7
17
5.5
0.27
8.1
11.1
13.9
7.6
0.81
0.55
5.3
17.7
4.9
20.6
OE-Rotor
yarn, carded
13.2
111
29
18*
4.3
0.31
9.2
12.8
16.4
8.9
0.77
0.40
6.9
13.4
5.1
14.8
12.9
110
15
24
4.0
0.28
8.1
13.6
17.1
11.0
0.77
0.50
6.5
13.5
6.0
15.1
10.5
5
9
28
5.1
0.27
8.2
10.5
12.6
6.6
0.84
0.54
6.5
18.8
6.0
21.5
CV2D
0.3 mm
Thick places
+50%
111
CV2D 8 mm
Thin places 40%
Ring yarn,
TENSORAPID TENSOJET
69
CVm
carded
USTER
13.8
Spinning
method
Ring yarn,
®
USTER
USTER® TESTER
Air-jet yarn
(Vortex),
combed
Compact
(Rotorcraft)
yarn,
combed
Ne 30, 100% cotton yarn
@
Thick places
+50%
Neps +200%
H
2DØ mm
CV2D 8 mm
CV2D
0.3 mm
CV1D
0.3 mm
CVFS
Shape
D
g/cm3
Elongation
Tenacity
Elongation
Tenacity
carded
Ring yarn,
combed
OE-Rotor
yarn, carded
TENSORAPID TENSOJET
18.1
836
663
918
5.3
0.23
14.3
19.1
20.9
12.7
0.83
0.49
6.4
15.2
6.0
17.5
11.5
16
20
64
4.2
0.20
8.7
11.7
13.6
7.8
0.84
0.60
6.2
19.9
5.9
22.7
16.0
980
166
130*
3.9
0.24
10.6
15.4
18.3
11.2
0.77
0.43
5.6
11.7
5.3
13.9
12.3
93
9
13
4.2
0.22
8.4
13.7
17.4
10.8
0.79
0.52
6.1
13.1
6.3
15.8
11.9
105
110
17
3.6
0.20
8.5
11.0
12.8
6.9
0.85
0.64
7.0
20.5
6.6
23.3
CVm
Ring yarn,
USTER
Thin places 40%
Spinning
method
@
USTER
USTER@ TESTER
Air-jet yarn
(MJS)
(50%CO
/50%Mod.)
Compact
yarn, (K44)
combed
Table 8
*
Comparison of different yarn spinning systems
Caution: It was decided as long ago as 30 years that neps in OE rotor yarn are compared with other spinning systems on
the level are +280% because neps are embedded much more in the yarn body and, therefore, not as disturbing as in the
case of ring-spun yarn. Therefore, the neps in Table 8 and the following graphs represent the values of +280%.
24 (40)
USTER® TESTER 5-S800
THE YARN INSPECTION SYSTEM
3.1.3
Comparison of mass variation CVm and hairiness
We can see from Table 8 that the spinning system has an important effect
not only on capacitive measurement values, but also on optical ones. In
order to explain and show the tendencies of every yarn spinning system,
the following graphs are shows (Fig. 24 to Fig. 33).
In Fig. 24 and Fig. 25, we can see the unevenness and the hairiness values
of five yarns, which have the quality parameters listed in Table 8.
15
Ring yarn,carded
Ring yarn,combed
12
OE-Rotor yarn, carded
Air-jet-yarn (Vortex),combed
Compact (Rotorcraft) yarn,combed
9
6
3
0
CVm
H
Fig. 24
Comparison of the evenness and hairiness values
of various 100% CO, Ne 20
yarns
When we look at the Ne 20 yarn, carded ring yarn, OE-rotor and Air-jet yarn
(Vortex) have higher CVm values, combed ring yarn and compact (Rotorcraft) yarn have lower CVm values. The mean value of the CVm for carded
ring yarn equals 13.8%. This is equivalent to the 40%-line of the USTER®
STATISTICS. The mean value of the CVm for compact (Rotorcraft) yarn
equals 10.5%. This is equivalent to 46%-line of the USTER® STATISTICS.
Air-jet yarn (Vortex) has the lowermost hairiness and the carded ring yarn
has the highest hairiness value (Fig. 24). The mean value of the hairiness
for Air-jet yarn (Vortex) yarn equals 4.03%. The mean value of the hairiness
for carded ring yarn equals 5.88%. This is equivalent to the 40%-line of the
USTER® STATISTICS.
Ring yarn,carded
20
Ring yarn,combed
OE-Rotor yarn, carded
16
Air-jet yarn (MJS) (50%CO/50%Modal)
Compact yarn,combed (K44)
12
8
4
0
CVm
USTER® TESTER 5-S800
H
Fig. 25
Comparison of the evenness and hairiness values
of various 100% CO, Ne 30
yarns (Exception: MJS)
25 (40)
THE YARN INSPECTION SYSTEM
When we look at the Ne 30 yarn (Fig. 25), carded ring yarn and OE-rotor
have higher CVm values whereas combed ring, air-jet (MJS) and compact
yarns have lower CVm values. The mean value of the CVm for carded ring
yarn equals 18.05%. This is equivalent to the 95%-line of the USTER®
STATISTICS. The mean value of the CVm for combed ring yarn equals
11.5%. This is equivalent to the 16%-line of the USTER® STATISTICS.
While compact yarn has the lowermost hairiness, carded ring yarn has the
highest hairiness value. The mean value of the hairiness for compact yarn
equals 3.61%. This is equivalent to the 54%-line of the USTER® STATISTICS. The mean value of the hairiness for carded ring yarn equals 5.31%.
This is equivalent to the 36%-line of the USTER® STATISTICS.
3.1.4
Comparison of imperfections
In Fig. 26 and Fig. 27, the thin places (-40%), thick places (+50%) and the
neps (+200%) values of each yarn are shown.
180
160
140
Ring yarn,carded
Ring yarn,combed
OE-Rotor yarn, carded
Air-jet-yarn (Vortex),combed
Compact (Rotorcraft) yarn,combed
120
100
80
60
40
20
Fig. 26
Comparison of the imperfections of 100% CO, Ne 20
yarns
0
Thin places -40%
Thick places +50%
Neps +200% (280%)
Because the number of thin places (-50%) are very close to zero, we have
chosen thin places (-40%). While OE-rotor and Vortex yarns have the highest number of thin place at a setting of -40%, combed ring and compact
yarns (Rotorcraft) have the lowermost values. When we look at the thick
places (+50%), carded ring yarn has the highest value. Combed ring and
compact yarns (Rotorcraft) have the lowermost number of thick places.
Carded ring yarns have the highest number of neps (+200%). Combed ring
yarn has the lowermost number of neps (+200%) value. Neps for OE rotor
yarn was determined at settings of +280% for the reasons mentioned
above.
26 (40)
USTER® TESTER 5-S800
THE YARN INSPECTION SYSTEM
Ring yarn,carded
Ring yarn,combed
OE-Rotor yarn, carded
Air-jet yarn (MJS) (50%CO/50%Modal)
Compact yarn,combed (K44)
1400
1200
1000
800
600
400
200
0
Thin places -40%
Thick places +50%
Neps +200% (280%)
Fig. 27
Comparison of the imperfections of 100% CO, Ne 30
yarns (Exception: MJS)
While OE-rotor and carded ring yarns have the highest number of thin
places (-40%), combed ring yarn has the lowermost value. When looking at
thick places (+50%), carded ring yarn has the highest value. Combed ring
and air-jet (MJS) yarns have the lowermost number of thick places. While
carded ring yarns have the highest number of neps (+200%), air-jet (MJS)
and compact yarns have the lowermost number of neps (+200%). The neps
of OE rotor yarn are again shown on a level of + 280% in Fig. 27.
3.1.5
Comparison of diameter 2DØ, shape and density
In Fig. 28 and Fig. 29, the diameter, shape and density values of each yarn
are shown.
1.0
Ring yarn,carded
Ring yarn,combed
0.8
OE-Rotor yarn, carded
Air-jet-yarn (Vortex),combed
0.6
Compact (Rotorcraft)
yarn,combed
0.4
0.2
0.0
2DØ
Shape
Density
Fig. 28
Comparison of the diameter, shape and density values of 100% CO, Ne 20
yarns
The diameter of the yarn (2DØ) is mainly determined by the number of fibers in the cross-section and the twist. Whereas OE-rotor yarn has the
highest diameter value, combed ring and compact yarn have the lowermost
diameter values.
USTER® TESTER 5-S800
27 (40)
THE YARN INSPECTION SYSTEM
The mean value of the yarn diameter for OE-rotor yarn equals 0.308 mm.
The mean value of the yarn diameter for both combed ring and compact
yarns (Rotorcraft) equals 0.265 mm.
The shape or the roundness of the yarn can considerably affect the appearance of a fabric. When the shape value is close to 1, it means this yarn
has a circular cross-section. In contrary to diameter, combed ring and compact yarns have the highest and OE-rotor and vortex yarns have the lowermost shape values. The mean value of the shape for compact yarn
equals 0.84. This is equivalent to the 50%-line of the USTER® STATISTICS. The mean value of the shape both for OE-rotor and Vortex yarns
equals 0.77. This is equivalent to the 30%-line of the USTER® STATISTICS
for OE-rotor yarns.
Density is an absolute measure for the compactness of a yarn. When comparing the density values, combed ring and compact yarns have the highest
and OE-rotor yarn has the lowermost density values. The mean value of
the density for combed ring yarn equals 0.55 g/cm3. This is equivalent to
the 5%-line of the USTER® STATISTICS. The mean value of the density for
OE-rotor yarn equals 0.4 g/cm3. This is equivalent to the 23%-line of the
USTER® STATISTICS.
1.0
Ring yarn,carded
Ring yarn,combed
OE-Rotor yarn, carded
0.8
Air-jet yarn (MJS) (50%CO/50%Modal)
Compact yarn,combed (K44)
0.6
0.4
Fig. 29
Comparison of the diameter, shape and density values of various 100% CO,
Ne 30 yarns
(Exception: MJS)
0.2
0.0
2DØ
Shape
Density
Whereas OE-rotor yarn has the highest diameter value, combed ring and
compact yarns have the lowermost diameter values. The mean value of the
yarn diameter for OE-rotor yarn equals 0.242 mm. The mean value of the
yarn diameter for compact yarns equals 0.198 mm.
In contrary to the diameter, combed ring and compact yarns have the highest and OE-rotor and air-jet yarns have the lowermost shape value. The
mean value of the shape for compact yarn equals 0.85. This is equivalent
to the 28%-line of the USTER® STATISTICS. The mean value of the shape
for OE-rotor yarn equals 0.77. This is equivalent to the 31%-line of the
USTER® STATISTICS.
28 (40)
USTER® TESTER 5-S800
THE YARN INSPECTION SYSTEM
When dealing with density values, compact and combed ring yarns have
the highest and OE-rotor yarn has the lowermost density values. The mean
value of the density for compact yarn equals 0.64 g/cm3. This is equivalent
to the 29%-line of the USTER® STATISTICS. The mean value of the density
for OE-rotor yarn equals 0.43 g/cm3. This is equivalent to the 5%-line of the
USTER® STATISTICS.
3.1.6
Comparison of three types of diameter variations and the
surface structure
In Fig. 30 and Fig. 31, we can see different CV values and the surface
structure CVFS of each yarn.
20
16
Ring yarn,carded
Ring yarn,combed
OE-Rotor yarn, carded
Air-jet-yarn (Vortex),combed
Compact (Rotorcraft) yarn,combed
12
8
4
0
CV2D (8mm)
CV2D (0.3mm)
CV1D (0.3mm)
CVFS
Fig. 30
Comparison of the different
CV values and the surface
structure of the yarn values
of various 100% CO, Ne 20
yarns (Exception: MJS)
CV2D 8mm is used as a measure of optical evenness. Its application is
similar to the mass evenness. In addition to mass evenness, it also represents variations of the density which can affect the appearance of fabrics.
In Fig. 30 we can see that carded ring yarn has the highest optical unevenness value and Vortex yarn has the lowermost value. The mean value of
the optical unevenness for carded ring yarn equals 10.53%. The mean
value of the optical unevenness for Vortex yarns equals 8.07%.
CV2D 0.3mm is used as an indicator of very short term variations of the
diameter along the yarn. In our example, carded ring yarn has the highest
and the compact yarn (Rotorcraft) has the lowermost value. The mean
value for carded ring yarn equals 14.52%. This is equivalent to the 34%-line
of the USTER® STATISTICS. The mean value of the compact yarn (Rotorcraft) equals 10.48%. This is equivalent to the 86%-line of the USTER®
STATISTICS. With this measuring method the OE rotor yarn and the air-jet
yarn are much more affected as a result of the wrapped fibers as mentioned in Table 1, because the length of the measuring zone has only a
length of 0,3 mm.
USTER® TESTER 5-S800
29 (40)
THE YARN INSPECTION SYSTEM
CV1D 0.3mm can be used for comparative purposes, for example for comparisons with results from other manufacturers of optical evenness testers
which only function one-dimensionally. In our example, carded ring yarn
has the highest and the compact yarn (Rotorcraft) has the lowermost value.
The mean value for carded ring yarn equals 17.52%. The mean value for
compact yarns (Rotorcraft) equals 12.63%. Also with this test method
yarns with wrapped fibers (air-jet and OE rotor yarn) are strongly affected
because of the short measuring zone of 0,3 mm.
The CV of the Fine Structure (CVFS) is the specific indicator for the
roughness of a yarn. It describes the short-term variation of a yarn in comparison to the variation of a measuring zone of 8 mm. Only the irregularity
increase between 0.3 mm and 8 mm cut length is taken into account. When
we look at the surface structure of the yarn values of these five yarns, Vortex and carded ring yarns have the highest values whereas the compact
yarn (Rotorcraft) has the lowermost value. The mean value of CVFS for
Vortex yarn equals 10.96%.
The mean value of the CVFS for compact yarns (Rotorcraft) equals 6.58%.
Since the
In Fig. 31 and in Fig. 32 a comparison is made between various types of
yarn with respect to several CV values and the surface structure of yarns.
Ring yarn,carded
Ring yarn,combed
OE-Rotor yarn, carded
Air-jet yarn (MJS) (50%CO/50%Modal)
Compact yarn,combed (K44)
24
20
16
12
8
Fig. 31
Comparison of the different
CV values and the surface
structure of the yarn values
of various 100% CO, Ne 30
yarns (Exception: MJS, 50%
CO / 50% Modal)
4
0
CV2D (8mm)
CV2D (0.3mm)
CV1D (0.3mm)
CVFS
In Fig. 31, we can see that carded ring yarn has the highest optical unevenness value and air-jet yarn has the lowermost value. The mean value
of the optical unevenness for carded ring yarn equals 14.34%. The mean
value of the optical unevenness for air-jet yarns equals 8.35%.
In our example, carded ring yarn has the highest and the compact yarn has
the lowermost CV2D 0.3mm value. The mean value of the CV2D 0.3mm for
carded ring yarn equals 19.13%. This is equivalent to the 95%-line of the
USTER® STATISTICS. The mean value of the CV2D 0.3mm for compact
yarn equals 10.95%. This is equivalent to the 66%-line of the USTER® STATISTICS.
30 (40)
USTER® TESTER 5-S800
THE YARN INSPECTION SYSTEM
In Fig. 31, carded ring yarn has the highest and the rotorcraft yarn has the
lowermost CV1D 0.3mm value. The mean value of the CV1D 0.3mm for
carded ring yarn equals 20.89%. The mean value of the CV1D 0.3mm for
compact yarn equals 12.83%.
When we look at the surface structure of the yarn values of these five
yarns, carded ring yarn has the highest value and compact yarn has the
lowermost value. The mean value of the CV of the Fine Structure for
carded ring yarn equals 12.66%. The mean value of the CV of the Fine
Structure for compact yarn equals 6.93%.
3.1.7
Comparison of tenacity and elongation
In Fig. 32 and Fig. 33, the elongation and tenacity values of the above mentioned yarns are given. These yarn characteristics are tested both on the
USTER® TENSORAPID and USTER® TENSOJET systems.
24
Ring yarn,carded
Ring yarn,combed
20
OE-Rotor yarn, carded
16
Air-jet-yarn (Vortex),combed
Compact (Rotorcraft)
yarn,combed
12
8
4
0
Elongation
Tenacity
Tensorapid
Elongation
Tenacity
Tensojet
Fig. 32
Comparison of the elongation and tenacity values of
various 100% CO, Ne 20
yarns
When we look at the measurement values of the USTER® TENSORAPID
system, OE-rotor yarn has the highest elongation value and carded ring
yarn has the lowermost elongation value. The mean value of the elongation
for OE-rotor yarn equals 6.92%. This is equivalent to the 26%-line of the
USTER® STATISTICS. The mean value of the elongation for carded ring
yarn equals 5.03%. This is equivalent to the 91%-line of the USTER® STATISTICS.
According to the test results of the USTER® TENSOJET system, OE-rotor,
yarn has the highest elongation values and carded ring yarn has the lowermost elongation value. The mean value of the elongation for compact
yarn (Rotorcraft) equals 6.03%. This is equivalent to the 80%-line of the
USTER® STATISTICS. The mean value of the elongation for carded ring
yarn equals 4.79%. This is equivalent to the 95%-line of the USTER® STATISTICS.
USTER® TESTER 5-S800
31 (40)
THE YARN INSPECTION SYSTEM
In both cases, compact yarn (Rotorcraft) has the highest tenacity values
and OE-rotor yarn has the lowermost value. The mean value of the compact yarn (Rotorcraft) equals 18.82 cN/tex and 21.49 cN/tex, respectively.
This is equivalent to the 60% and 64% -lines of the USTER® STATISTICS,
respectively. The mean value of the tenacity for OE-rotor yarn equals 13.4
cN/tex and 14.81 cN/tex, respectively. This is equivalent to the 31% and
36% -lines of the USTER® STATISTICS, respectively.
In Fig. 33 a comparison is made between the tenacity and the elongation
for a 100% cotton yarn, Ne30.
24
Ring yarn,carded
20
Ring yarn,combed
OE-Rotor yarn, carded
16
Air-jet yarn (MJS)
(50%CO/50%Modal)
12
Compact yarn,combed (K44)
8
4
Fig. 33
Comparison of the elongation and tenacity values of
various 100% CO, Ne 30
yarns (Exception: MJS)
0
Elongation
Tensorapid
Tenacity
Elongation
Tenacity
Tensojet
When we look at the measurement values of the USTER® TENSORAPID
system, compact yarn has the highest elongation value and OE-rotor yarn
has the lowermost value. The mean value of the elongation for compact
yarn equals 6.95%. This is equivalent to the 17%-line of the USTER® STATISTICS. The mean value of the elongation for OE-rotor yarn equals
5.56%. This is equivalent to the 62%-line of the USTER® STATISTICS.
According to the test results of the USTER® TENSOJET system, compact
yarn has again the highest elongation value and OE-rotor yarn has the lowermost value. The mean value of the elongation for compact yarn equals
6.58%. This is equivalent to the 23%-line of the USTER® STATISTICS. The
mean value of the elongation for OE-rotor yarn equals 5.26%. This is
equivalent to the 50%-line of the USTER® STATISTICS.
According to the test results of both systems, compact yarn has the highest
tenacity values and OE-rotor yarn has the lowermost value. The mean
value of the tenacity for compact yarn equals 20.05 cN/tex (USTER® TENSORAPID) and 23.25 cN/tex (USTER® TENSOJET). This is equivalent to
the 55% and 60% -lines of the USTER® STATISTICS, respectively. The
mean value of the tenacity for OE-rotor yarn equals 11.72 cN/tex and 13.86
cN/tex, respectively. This is equivalent to the 58% and 43% -lines of the
USTER® STATISTICS, respectively.
32 (40)
USTER® TESTER 5-S800
THE YARN INSPECTION SYSTEM
3.2
Variation of the effective mean yarn diameter
This example illustrates how a diameter variation can affect the appearance
of the end product after processing. Table 9 shows the quality parameters
for a combed ring yarn with a count of Nec 20, 100% cotton.
No.
CVm
H
sh
1
2
3
4
5
6
11.37
11.39
11.59
11.24
11.14
11.66
6.65
6.27
6.50
5.88
6.31
5.71
Mean
CV
Q95
Max
Min
11.40
1.8
0.21
11.66
11.14
6.05
7.1
0.45
6.65
5.50
Table 9
CV2D
8mm
CV2D
0.3mm
CV1D
0.3mm
CV FS
Shape
D
g/cm3
1.45
1.40
1.17
1.33
1.26
1.14
2D
mm
0.293
0.289
0.272
0.273
0.307
0.278
8.93
8.96
9.02
8.84
9.24
9.81
12.22
12.28
12.44
12.36
12.39
13.25
14.30
14.41
14.53
14.34
14.49
15.22
8.35
8.41
8.57
8.64
8.26
8.91
0.85
0.84
0.84
0.85
0.84
0.84
0.44
0.45
0.51
0.50
0.40
0.49
1.29
9.4
0.13
1.45
1.14
0.285
4.8
0.014
0.307
0.272
9.13
3.9
0.38
9.81
8.84
12.49
3.1
0.40
13.25
12.22
14.55
2.3
0.35
15.22
14.30
8.52
2.8
0.25
8.91
8.26
0.84
0.4
0.00
0.85
0.84
0.46
9.3
0.05
0.51
0.40
Quality report of USTER TESTER 5-S800
Fig. 34 shows the diagrams of the diameter of two bobbins from the same
measurement series. The second diagram indicates a marked increase of
the diameter of bobbin 5 (higher and more peaks above 0.4 mm).
Bobbin 4: Yarn count 29.7 tex / 2DØ 0.273 mm
Bobbin 5: Yarn count 29.3 tex / 2DØ 0.307 mm
Fig. 34
Diagrams of the mean yarn
diameter of bobbins 4 and
5
USTER® TESTER 5-S800
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THE YARN INSPECTION SYSTEM
There were no apparent differences in the mass and hairiness diagrams.
But the count determination showed that the yarn with the larger diameter
was even a little finer than the yarn with the smaller diameter. This leads to
the conclusion that the differences were caused by twist variations and,
with approximately the same number of fibers in the cross-section, this has
an immediate effect on the mean diameter, and therefore, on the yarn density. The percentage differences of the two bobbins are illustrated once
more in Table 10, whereby the measurement values of bobbin 4 represent
100%.
Ring yarn
CVm
H
sh
2DØ
CV2D
CV2D
CV1D
8 mm
0.3 mm
0.3 mm
mm
%
%
%
%
combed
CVFS
Shape D
g/cm3
100% cotton
%
Bobbin 4
11.24
5.88
1.33
0.273
8.84
12.36
14.34
8.64
0.85
0.50
Bobbin 5
11.14
6.31
1.26
0.307
9.24
12.39
14.49
8.26
0.84
0.40
Deviation in %
0
+7
-5
+12
+5
0
+1
-4
-1
-20
Table 10 Comparison of the bobbins 4 and 5
With a specific density of cotton fibers from 1.5 – 1.54 g/cm³, it can be derived that a combed ring-spun yarn reaches on average approx. 30% of the
specific density of a cotton fiber. Measurements of yarns with the same
yarn count, but different twist levels, have shown that a significant increase
of density is possible by increasing the twist levels. With a combed ringspun yarn, count Nec 100 (Nm 170, 6 tex), a 10% increase of the twist resulted in a decrease of the mean diameter by 10%. The density, on the
other hand, increased from 0.48 to 0.62, which represents a 22% increase.
The following Fig. 35 and Fig. 36 show the knitted fabrics, single-jersey, of
the two yarns made on a single-system laboratory knitting machine. It can
be seen quite clearly that a smaller yarn diameter, which also results in a
higher density, causes the contours in the knitted fabric to be sharply accentuated. The effect is also intensified by the slightly lower hairiness
H (-7%).
Fig. 35
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2D - Diameter = 0.273mm / Density =0.5 g/cm3
Fig. 36
2D - Diameter = 0.307mm / Density =0.4 g/cm3
USTER® TESTER 5-S800
THE YARN INSPECTION SYSTEM
It is obvious that, in the final dying process, any differences in the dyeability
of the two yarns will make the end product unusable. The yarn with the
smaller diameter (means higher density) will appear darker, because the
same amount of dye is applied to a smaller surface (Fig. 37).
Fig. 37
Effect of a diameter
variation on the dyeability
4
Additional information gained by combination
of opto-electronic and capacitive sensors
The following are a few considerations what kind of additional information is
available with both sensors:

It is obvious based on this report that the analysis of both the optical
and the capacitive signal provides additional information which contributes to a better understanding of quality deficiencies of yarns.

The yarn density is, naturally, in close relationship with yarn twist.

The „hand (handle)“ of a fabric depends mainly on the density of the
yarn which it incorporates. It also must be mentioned, though, that the
hand also depends on the yarn hairiness. Trials with carded rotor- spun
yarns, which were produced with different types of yarn doffing tubes,
have shown that yarn density is inversely proportional to yarn hairiness,
the yarn mass showing no difference (Fig. 38).

The options of the optical sensor are shown in this paper. If also shows
the strengths of the optical system. The capacitive system is, however,
superior for analyzing all kinds of drafting problems and for investigations of yarn faults which do not deviate significantly from the yarn body.
USTER® TESTER 5-S800
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THE YARN INSPECTION SYSTEM
Fig. 38 shows the effect of different types of navels on an OE-rotor spinning
machine on the density, the formation of hairiness and evenness.
Density
100%
- 6%
- 17%
50%
spiral shaped navel
4k4 yarn doffing tube
rip shaped navel
Hairiness
+ 68%
+ 15%
100%
spiral shaped navel
4k4 yarn doffing tube
rip shaped navel
Evenness
100%
50%
spiral shaped navel
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4k4 yarn doffing tube
rip shaped navel
Fig. 38
Density, hairiness and the
evenness CVm of carded
OE rotor-spun yarns, which
were done with different
types of yarn doffing tubes
USTER® TESTER 5-S800
THE YARN INSPECTION SYSTEM
5
Conclusion
After years of intensive basic research and development, Uster Technologies offers the optoelectronic sensor OM for the USTER TESTER 5-S800,
which permits a two-dimensional assessment and quality monitoring of the
yarn diameter. This measuring principle is independent of the yarn shape
(roundness), and, therefore, provides additional information. Using the
nominal yarn count as a reference, it is also possible to provide information
on the density of the tested yarn.
In the future, the diameter measurement in the textile laboratory will become more important in order to compare the quality characteristics of various spinning technologies and to establish quality management methods
for all kind of spinning systems. With some yarns, the advantages of the
optical method are quite obvious. With regard to the visual impression of a
yarn, which is also affected by short-term variations, the optoelectronic
measurement opens up new ways and possibilities of describing the quality
of yarns in even more detail. This will probably lead to further interesting
developments in the years ahead. It should be kept in mind, however, that
the spinning process is a manufacturing process with only one objective: a
constant mass flow. Or to put it another way, the spinner’s goal is to produce the same number of fibers in the cross-section at every point along
the spinning process. A constant number of fibers in the cross-section
means constant mass, and mass variations are determined by capacitive
methods.
The optical testing method as applied by the sensor OM of the USTER®
TESTERS 4 and 5 is able to provide additional information on the diameter,
diameter variation, the density, the shape and the surface structure of a
yarn.
The measuring zone of the capacitive measuring system has a length of 8
mm. With the sensor OM the operator can select a measuring zone length
of 8 mm as well as 0.3 mm. For this reason the sensor also allows the
measurement of very short variations of a yarn which is particularly helpful
for detailed measurements of wrapped fibers in OE rotor and air-jet yarns
and for the measurement of neps.
With the USTER® TESTERS 4 and 5 the optical sensor OM can be used
together with other sensors. Therefore, the simultaneous measurement of
the same piece of yarn by capacitive and optical sensors allows a significantly more detailed analysis of yarns.
USTER® TESTER 5-S800
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THE YARN INSPECTION SYSTEM
6
Literature
1. Lawrence, C.,A., “Fundamentals of Spun Yarn Technology”, CRC Press
LLC, 2003.
2. Lord, P. R., “Handbook of Yarn Production: Technology, Science and
Economics”, Woodhead Publishing Limited, 2005.
3. Oxenham, W., “Fasciated Yarns – A Revolutionary Development ?”,
Journal of Textile and Apparel Technology and Management, Volume1,
Issue 2, 2001.
4. USTER® TESTER 5 Application Handbook: “Laboratory system for the
measurement of yarns, rovings and slivers”, V1.2, 410 106-04020, June
2007.
5. USTER® News Bulletin No 44: USTER® TESTER 5: “A Multi-purpose
Laboratory System for the analysis of spun yarns”, October 2005.
6. Söll, W. “Determination of the yarn quality with revolutionary sensor
technology”, USTER® TESTER 5, Application Report, SE 555, September 2005 / Edition 2: July 2008.
7. Söll, W. “Principles of measurement of the opto-electronic sensor OM”,
USTER® TESTER 5, Application Report, SE 554, 2001 / Edition 2: July
2008.
8. Söll, W. “Comparison of the capacitive and optical measuring methods
to determine evenness”,”, USTER® TESTER 5, Application Report, SE
564, 2000 / Edition 2: July 2008
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USTER® TESTER 5-S800
THE YARN INSPECTION SYSTEM
USTER® TESTER 5-S800
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THE YARN INSPECTION SYSTEM
Uster Technologies AG
Wilstrasse 11
CH-8610 Uster / Switzerland
Phone +41 43 366 36 36
Fax
+41 43 366 36 37
www.uster.com
[email protected]
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USTER® TESTER 5-S800