the measurement of the yarn diameter, density and shape of yarns

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


Copyright 2009 by Uster Technologies AG All rights reserved. No part of this publication may be reproduced, stored in a re-trieval system, translated or transmitted in any form or by any means, electroni-cally, mechanically, photocopying, recording or otherwise, without the prior permis-sion 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

2 (40) USTER® TESTER 5-S800


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 opto-electronic and capacitive sensors.......................................... 35

5 Conclusion................................................................................ 37

6 Literature................................................................................... 38

USTER® TESTER 5-S800 3 (40)


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 “opti-cal” 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 meas-ured. The USTER® TESTER 5 uses two parallel light beams creating double illu-mination on the yarn to measure these parameters optically in a two-dimensional environment at a high degree of precision. Unlike yarn hairiness, most spinners are not familiar with these measure-ments. 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 modi-fied 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 a compact yarn

Structure of an OE rotor yarn Structure of Vortex yarn

Fig. 1 Yarn surface structure measurements by USTER® TESTER 5



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 sur-face fiber arrangement and the density.

The variation of the diameter of the yarn at 0.3 mm is affected by the short sur-face faults (neps), the seed coat fragments, the wrapped fibers, etc.

The shape (roundness) of the yarn depends on the spinning preparation, the spinning system and the yarn type.

Table 1 USTER® TESTER 5 Optical sensor OM

The difference between these surface parameters and the traditional ap-pearance 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 capaci-tive 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 proc-ess. 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 prod-uct 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 capaci-tive 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 be-tween very small segments in the yarn.



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 yarnwith 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 pa-rameters 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. 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.

fill

ing

dwarp

warp

Plain weave

Knit fabric

dfil

ling

Woven fabric

Fabric cover factor:

Warpwise cover factor = CFwarp = dwarp/warp

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]

w = the wale spacing [W=1/w = wales/inch]

d = yarn diameter

Fig. 3 Utilization of yarn diameter for estimating fabric structural parameters



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 2 Receiver 1

Yarn

Light source 1 Light source 2

MirrorMirror

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 diame-ter. 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.



No.

2D

mm

CV2D

8mm

CV2D

0.3mm

CV FS CV1D

0.3mm

Shape D

g/cm3

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

CV

Q95

Max

Min

USP 07

0.187

1.2

0.002

0.190

0.183

10.30

1.3

0.10

10.51

10.12

13.21

0.9

0.08

13.35

13.02

57

8.27

1.0

0.06

8.39

8.18

15.79

1.0

0.12

16.07

15.54

0.81

0.9

0.01

0.82

0.79

64

0.54

1.7

0.01

0.56

0.53

34

Table 2 Results obtained with the optical sensor OM

Quality

parameter 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 ap-parent. 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 even-ness; 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.



Fig. 6 shows a variance-length curve and the values of a Ne 24, 100% cot-ton, ring-spun, combed yarn with a measuring zone of 8 and 0.3 mm.

1

2

3

5

10

20

0,01 0,1 1 10 100 cmCut length

%CV

CV 2D 0,3 mm

CV 2D 8 mm

Fig. 6 Variance-length curve, CV 2D 0.3 mm = 18.45% CV 2D 8 mm = 11.54%

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® STATIS-TICS.

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 Fig. 7 USTER® STATISTICS 2007,combed, ring-spun yarn, CV 2D 0,3 mm



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 cross-section, 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 no-ticed 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 inser-tion 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.

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

30 60 24 30 36 41 30 40 50 65 100 7 12 16 20 35 24 33 16 30

Combed CardedYarn Count (Ne)

2D

Ø (

mm

)

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 dif-ferent yarn spinning tech-niques

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.




5 10

5texNe

0,1

0,2

0,3

0,4

0,5

0,6

(mm) Diameter

10 20 40 60 80 100120 60 30 15 7,51

200 6

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

0,4

0,7

(g/cm )3

Density

3020

texNe

0,5

0,6

5 10 15 20 25120 60 3040 24

Fig. 10 Density versus Yarn Count.Yarn: ring-spun, combed, for woven fabrics

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, pro-duction problems such as slow spindles can be detected by evaluating this parameter. As we mentioned before, the density of a yarn provides an indi-cation 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 de-pends 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 den-sity of fine yarns is always higher than coarse yarns.



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:

︶3︵g/cm510texπ2d

4

︶3︵g/cmm

π2d4

gD4π2d

D

D

m

m = Mass of yarn (g)

d = Yarn diameter (cm)

= Length of yarn (cm)

D = Yarn density (g/cm3)

︵g/cm ︶countYarnm

= 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)

34

45

25

2g/cm0,59

3,14103,24

101,541015

π0,018

410tex

πd

4D

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.

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

30 60 24 30 36 41 30 40 50 65 100 7 12 16 20 35 24 33 16 30

Combed CardedYarn Count (Ne)

Den

sity

(g

/cm

3 )

Compact Ring-combed (knitting) Ring-combed (weaving) OE-rotor Ring-carded (knitting) Ring-carded (weaving)

Fig. 11 Density values of the se-lected 790 yarns according to different yarn spinning techniques


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/cm3

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

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 spin-ning 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

b

Shape =ab

The shape is a factor which in-dicates the average yarn round-ness over the entire test length of the yarn. The value corre-sponds to the ratio of the short to the long main axis of an el-lipse (1 = circular). Fig. 13

Definition of shape



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).



2.4 The CV of the Fine Structure The CV of the Fine Structure is the specific indicator for a yarn’s rough-ness. 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 dia-grams 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 ge-ometry 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 even-ness and reduced imperfections [1]. Fig. 15 shows that the compact spin-ning system avoids the formation of the spinning triangle. This results in a minimum number of protruding fibers.



Fig. 15 Spinning triangle of com-pact 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].



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 spin-ning system consists of a 3-over-3 high speed roller drafting unit, two com-pressed-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 sys-tem is a single air-jet spinning system. When we compare with the tandem jet system, it incorporates a modified jet inlet.



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 sys-tem [1]

The optical sensor OM of the USTER® TESTERS 4 and 5 is able to deter-mine 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 ex-press the characteristics of the yarns:

- High mass variation of carded ring-spun yarn, regular mass varia-tion 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 “draft-ing 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 prob-lems 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.



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 Spectrograms of mass, hairiness and yarn diameter (Ne 20, 100% cotton yarns)



OE-yarn Air-jet (Vortex) Compact (Rotorcraft)

OE-yarn Air-jet (Vortex) Compact (Rotorcraft)



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 Spectrograms of mass, hairiness and yarn diameter (Ne 30, 100% cotton yarns )



OE-yarn Air-jet (MJS)

(50% CO / 50% Modal) Compact (K44)

OE-yarn Air-jet (MJS)

(50% CO / 50% Modal) Compact (K44)



Table 8 shows the quality characteristics of these yarns.

Ne 20, 100% cotton yarn

USTER® TESTER USTER®

TENSORAPID

USTER®

TENSOJET

Spinning

method

CV

m

Th

in p

lace

s -

40%

Th

ick

pla

ces

+50

%

Nep

s +

200

%

H

2DØ

mm

CV

2D 8

mm

CV

2D

0.3

mm

CV

1D

0.3

mm

CV

FS

Sh

ape

D

g/c

m3

Elo

ng

atio

n

Ten

acit

y

Elo

ng

atio

n

Ten

acit

y

Ring yarn,

carded 13.8 69 111 172 5.9 0.28 10.5 14.5 17.5 10.0 0.79 0.49 5.0 16.1 4.8 18.8

Ring yarn,

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

Air-jet yarn

(Vortex),

combed

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

Compact

(Rotorcraft)

yarn,

combed

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

Ne 30, 100% cotton yarn

USTER@ TESTER USTER@

TENSORAPID

USTER@

TENSOJET

Spinning

method

CV

m

Th

in p

lace

s -

40%

Th

ick

pla

ces

+50

%

Nep

s +

200

%

H

2DØ

mm

CV

2D 8

mm

CV

2D

0.3

mm

CV

1D

0.3

mm

CV

FS

Sh

ape

D

g/c

m3

Elo

ng

atio

n

Ten

acit

y

Elo

ng

atio

n

Ten

acit

y Ring yarn,

carded 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

Ring yarn,

combed 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

OE-Rotor

yarn, carded 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

Air-jet yarn

(MJS)

(50%CO

/50%Mod.)

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

Compact

yarn, (K44)

combed

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

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%.



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.

0

3

6

9

12

15

CVm H

Ring yarn,carded

Ring yarn,combed

OE-Rotor yarn, carded

Air-jet-yarn (Vortex),combed

Compact (Rotorcraft) yarn,combed

Fig. 24 Comparison of the even-ness 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 (Rotor-craft) 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.

0

4

8

12

16

20

CVm H

Ring yarn,carded

Ring yarn,combed


Air-jet yarn (MJS) (50%CO/50%Modal)

Compact yarn,combed (K44)

Fig. 25 Comparison of the even-ness and hairiness values of various 100% CO, Ne 30 yarns (Exception: MJS)



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® STATIS-TICS. 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.

0

20

40

60

80

100

120

140

160

180

Thin places -40% Thick places +50% Neps +200% (280%)

Ring yarn,carded

Ring yarn,combedOE-Rotor yarn, carded

Air-jet-yarn (Vortex),combed Compact (Rotorcraft) yarn,combed

Fig. 26 Comparison of the imper-fections of 100% CO, Ne 20 yarns

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 high-est 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.



0

200

400

600

800

1000

1200

1400

Thin places -40% Thick places +50% Neps +200% (280%)

Ring yarn,carded

Ring yarn,combed




Fig. 27 Comparison of the imper-fections 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.

0.0

0.2

0.4

0.6

0.8

1.0

2DØ Shape Density

Ring yarn,carded

Ring yarn,combed



Compact (Rotorcraft)yarn,combed

Fig. 28 Comparison of the diame-ter, shape and density val-ues of 100% CO, Ne 20 yarns

The diameter of the yarn (2DØ) is mainly determined by the number of fi-bers 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.



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 ap-pearance 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 com-pact yarns have the highest and OE-rotor and vortex yarns have the low-ermost shape values. The mean value of the shape for compact yarn equals 0.84. This is equivalent to the 50%-line of the USTER® STATIS-TICS. 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 com-paring 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.

0.0

0.2

0.4

0.6

0.8

1.0

2DØ Shape Density

Ring yarn,carded

Ring yarn,combed




Fig. 29 Comparison of the diame-ter, shape and density val-ues of various 100% CO, Ne 30 yarns (Exception: MJS)

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 high-est 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.



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.

0

4

8

12

16

20

CV2D (8mm) CV2D (0.3mm) CV1D (0.3mm) CVFS

Ring yarn,carded

Ring yarn,combed



Compact (Rotorcraft) yarn,combed

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 repre-sents 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 uneven-ness 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 (Rotor-craft) 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 men-tioned in Table 1, because the length of the measuring zone has only a length of 0,3 mm.



CV1D 0.3mm can be used for comparative purposes, for example for com-parisons 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 com-parison 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, Vor-tex 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.

0

4

8

12

16

20

24

CV2D (8mm) CV2D (0.3mm) CV1D (0.3mm) CVFS

Ring yarn,cardedRing yarn,combedOE-Rotor yarn, carded Air-jet yarn (MJS) (50%CO/50%Modal)Compact yarn,combed (K44)

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)

In Fig. 31, we can see that carded ring yarn has the highest optical un-evenness 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® STA-TISTICS.



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 men-tioned yarns are given. These yarn characteristics are tested both on the USTER® TENSORAPID and USTER® TENSOJET systems.

0

4

8

12

16

20

24

Elongation Tenacity Elongation Tenacity

Tensorapid Tensojet

Ring yarn,carded

Ring yarn,combed



Compact (Rotorcraft)yarn,combed

Fig. 32 Comparison of the elonga-tion 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® STA-TISTICS. According to the test results of the USTER® TENSOJET system, OE-rotor, yarn has the highest elongation values and carded ring yarn has the low-ermost 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® STA-TISTICS.



In both cases, compact yarn (Rotorcraft) has the highest tenacity values and OE-rotor yarn has the lowermost value. The mean value of the com-pact 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.

0

4

8

12

16

20

24

Elongation Tenacity Elongation Tenacity

Tensorapid Tensojet

Ring yarn,carded

Ring yarn,combed


Air-jet yarn (MJS)(50%CO/50%Modal)


Fig. 33 Comparison of the elonga-tion and tenacity values of various 100% CO, Ne 30 yarns (Exception: MJS)

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® STA-TISTICS. 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 low-ermost 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® TEN-SORAPID) 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.



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 2D mm

CV2D 8mm

CV2D 0.3mm

CV1D 0.3mm

CV FS Shape D g/cm3

1 11.37 6.65 1.45 0.293 8.93 12.22 14.30 8.35 0.85 0.44

2 11.39 6.27 1.40 0.289 8.96 12.28 14.41 8.41 0.84 0.45

3 11.59 6.50 1.17 0.272 9.02 12.44 14.53 8.57 0.84 0.51

4 11.24 5.88 1.33 0.273 8.84 12.36 14.34 8.64 0.85 0.50

5 11.14 6.31 1.26 0.307 9.24 12.39 14.49 8.26 0.84 0.40

6 11.66 5.71 1.14 0.278 9.81 13.25 15.22 8.91 0.84 0.49

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

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

Table 9 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



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 den-sity. 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

combed

100% cotton

CVm

%

H

sh

2DØ

mm

CV2D

8 mm

%

CV2D

0.3 mm

%

CV1D

0.3 mm

%

CVFS

%

Shape

D

g/cm3

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 de-rived 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 ring-spun yarn, count Nec 100 (Nm 170, 6 tex), a 10% increase of the twist re-sulted 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 ac-centuated. The effect is also intensified by the slightly lower hairiness H (-7%).

Fig. 35 2D - Diameter = 0.273mm / Density =0.5 g/cm3 Fig. 36 2D - Diameter = 0.307mm / Density =0.4 g/cm3



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 contrib-utes 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 investiga-tions of yarn faults which do not deviate significantly from the yarn body.



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%

50%

spiral shaped navel 4k4 yarn doffing tube rip shaped navel

- 6%

- 17%

Hairiness

100%


+ 15%

+ 68%

Evenness

100%

50%


Fig. 38 Density, hairiness and the evenness CVm of carded OE rotor-spun yarns, which were done with different types of yarn doffing tubes



5 Conclusion After years of intensive basic research and development, Uster Technolo-gies 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 be-come more important in order to compare the quality characteristics of vari-ous 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 pro-duce 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 signifi-cantly more detailed analysis of yarns.



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, Septem-ber 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 measurement of the yarn diameter, density and shape of yarns

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