polyester – lyocell blend on air-jet spinning for …...the polyester/lyocell blend was...

Premkumar GovindarajuluProcess AnalyticsRieter Machines & Systems

Harald SchwipplHead Technology & Process AnalyticsRieter Machines & Systems

Polyester – Lyocell Blend on Air-Jet Spinning for Weaving Application

February 2018

2

Rieter . Polyester – Lyocell Blend on Air-Jet Spinning for Weaving Application

Content

1. Potential for Air-Jet Spinning Technology 3

2. Application Areas of different End Spinning Technologies 4

3. Trial Conditions 5

3.1. Raw Material 5

3.2. Technology Components and Machine Settings 6

4. Fiber Preparation Results 9

5. Further Improvement in Yarn Structure 11

6. Yarn Quality over the Blend Ratio Polyester and Lyocell 13

7. Influence of Plyed Air-Jet Yarn 22

7.1. Two-Ply Yarn Quality 23

8. Fabric Quality 30

8.1. Fabric Quality Greige 32

8.2. Fabric Quality Finished 34

9. Economy 37

10. Summary 38

10.1. Single Yarn 38

10.2. Two-Ply Yarn 38

10.3. Weaving and Fabric 38

10.4. Economy 38

3


1. Potential for Air-Jet Spinning Technology

During the market launch of air-jet spin-ning, the range of possible application became increasingly established as new findings constantly emerged. Neverthe-less, the technological market potential has not been achieved by far. The techni-cal innovations and modifications on the machine make an increasing rise in oper-ational reliability with various raw mate-rials and yarn finenesses.

If a staple yarn production with 45 mil-lion tons per year and an air-jet yarn pro-duction potential of 10%, an average yarn fineness of 15 tex (Ne 40) and an average delivery speed of 420 m/min is presumed, then today an absolute air-jet spinning unit number of approx. 1.8 million resp. 38 million spindle equiva-lents can be considered as technological-ly realistic. Worldwide, up to 2016, only 0.29 million air-jet spinning units, that is 5.8 million spindle equivalents, were in-stalled. (Fig. 1 + 2) In this respect, a mul-tiple increase could be expected in the next few years compared to the current air-jet capacities. As the global consump-tion of staple fiber yarn also continues to increase, the air-jet spin unit potential will also additionally increase.

The time period up to the full exploita-tion of the technical potential is hard to assess. Experience with compact spin-ning has shown that a period of up to 15 years can certainly be considered as re-alistic until full utilization in the textile industry is achieved.

Fig. 1 - Air-jet spinning machine J 26

Inst

alle

d un

its e

quiv

alen

t [m

illio

n]

180

160

140

120

100

80

60

40

20

0

Spinning Process 2016Equivalent units vs. end spinnning, calculation based on 45 million tons per year

Fig. 2 - Economy Source: Rieter

Source: Rieter

161.295

20.905 25.746

43.700

8.324 4.328 1.472

Ring carded

Compactcarded

RotorRingcombed

Compactcombed

Air-jetcarded

Air-jetcombed

14.054

4


2. Application Areas of different End Spinning Technologies

In practice, the application range for air-jet yarns continually expands and is ac-celerated by constant machine develop-ment. This makes it possible to go even closer to raw material and yarn fineness limits.

If we examine the various end spinning processes, taking into account the re-spective raw materials, the very high flexibility in favor of the ring spinning technology is here apparent. In this con-nection, the use of natural fibers or fibers from natural polymers provides a very wide spectrum.

As well as the high flexibility of ring spinning to process different raw mate-rials and yarn counts, the flexibility to produce special structures, effects and multi-component yarns should also be mentioned such as:• twin yarns (twin and compact twin yarn

= spin-twisted)• fancy yarns • core yarns

In contrast, the processing of 100% syn-thetic fibers such as 100% polyester has certain limitations with compact and air-jet spinning. (Fig. 3)

The respective advantages of the differ-ent yarn structures are reflected in the yarn application (Fig. 4). So, for instance, more than 60% of air-jet yarns are used in knitting.

Source: Technology Process Analytics

Application Area of End Spinning Depending on Raw Material Use

Fig. 3 - Application area of end spinning depending on raw material use

Typical application Possible application Possible application with restrictions

Air-jet

Compact

Ring

Rotor

MMFcellulosics

Blends MMFsynthetics

Natural MMFsynthetics

Regrind

ViscoseLyocellModal

CO / MMFMMF/ MMF

Acryl Cotton Polyester Different raw material

Appl

icat

ion

ofPe

rcen

tage

100908070605040302010

0

Yarn Application by Spinning Technology

Fig. 4 - Yarn application by spinning technology Source: PCI 2015, RYS 2016

Air-jet RingCompact Rotor

Knitting Weaving

5


3. Trial Conditions

The air-jet spinning technology has so far been primarily used in the range of knitting, because of the unsurpassable pilling performance. The demand to use air-jet yarn in weaving is in-creasing. To further explore the limits, the question of highly stable, air-spun yarns for weaving arises, that not only can be excellently processed in weft but also in warp when using an innovative raw material blend.

Hence, this analysis deals with the production of fabric from air-jet yarns with a simultaneous comparison to a ring yarn, so as to better assess and evaluate the values achieved.

3.1. Raw Material

For this reason, a polyester/lyocell blend was selected as the raw material (Fig. 5), which should give an optical wool char-acteristic for the application area of suiting or coat materials.

The following objectives were therefore pursued:• To use fiber with highest strength, to reach the highest yarn

strength for best running condition in the weaving process using the air-jet yarn in warp and weft.

• To see the impact of air-jet two-ply yarn.• To find out if there is the same wool characteristic using poly-

ester/lyocell blend instead of polyester/viscose blend.• To find out if the wool characteristic effect is dependent on

the blend ratio.

TIFICO Polyester (PES)Bright

Fiber fineness: 1.37 dtexCut length: 38 mmStrength: 57 cN/tex

Elongation: 21%

TENCEL® Lenzing (CLY)Bright

Fiber fineness: 1.3 dtexCut length: 38 mmStrength: 41 cN/tex

Elongation: 13%

Fig. 5 – Raw material Source: Lenzing, TIFICO

6


1

1

5

5

3

3

7

7

9

9

2

2

6

6

4

4

8

8

Spinning Tip

Top and Bottom Apron

Spinning Nozzle

Spacer

Top Roller

Feed Condenser

Apron Condenser

Bottom Take-Up Roller

Infeed Draft Change Gear

Nozzle and distance Raw material Yarn count rangeZ – 2 = 18.6 mm Cotton Ne 20 - 50Z – 1 = 19.6 mm PES/CO, CV, CLY, Modal Ne 20 - 80Z + 1 = 21.6 mm PES, CV, CLY, PES / CLY Ne 25 - 60

Fig. 7 - Technology components J 26

Fig. 6 - Technology components J 26


Source: Rieter

3.2. Technology Components and Machine Settings

Different components and setting op-tions on the air-jet spinning machine J 26 (Fig. 6) support a wide application range of raw material types and yarn counts.

So, for example, the technologically im-portant parameters depending on raw material, fiber length and yarn count can be selected, such as the distance from the spinning tip to the gripping point of the delivery cylinder. (Fig. 7)

7


The machine setting for all raw material blends has been selected as follows:(Fig. 8)

Fig. 8 - Machine setting J 26 Source: TIS 27284 / Technology Process Analytics

Setting and componentsSpinning draft [-fold] 1.0

Pre draft [-fold] 1.78Intermediate draft [-fold] 2.31

Break draft [-fold] 4.10Main draft [-fold] 45.35

Top roller Middle/Infeed [type / mm] R 174 / 30.0Top roller Delivery [type / ⌀ mm] R 170 / 29.5

Apron top roller [type / ⌀mm] Steel roller / 27.8Top apron [type / ⌀mm] Yamauchi / TA-J 2/39.2

Bottom apron [type / ⌀mm] Yamauchi / TA-J 2/39.2Spacer pin [mm / colour] 3.5 brown

Infeed condenser [mm / colour] 8.0 x 2.5mm / redCondenser VF [mm / colour] 4.5 x 1.2mm / redCondenser ZF [mm / colour] 10.0 x 2.5mm / blue

Cylinder distance top roller [mm] 48-46-49Cylinder distance bottom roller [mm] 48-45-47

Setting and componentsSliver weight [tex] 2700Total draft [-fold] 185.9

Delivery speed [m/min] 380.0Spinning air pressure [bar] 6

FFE [type] Z + 1Spinning tip [type / ⌀ mm] U 1.0mm

Distance FFE - twist element [mm] 1.3

Polyester/lyocell, 1.3 dtex, 38mm, Ne 40

8


Delivery

Middle

Infeed

TOP ROLLER

R 170 70° Shore R 174 74° Shore R 180 80° Shore

TOP AND BOTTON APRONFOR MMF - BLENDS

Bottom Top

SPACER

3.00 mm 3.25 mm 3.50 mm 4.00 mm

SPINNING NOZZLE

FFE Distance 1.3 mm

SPINNING TIPFOR MMF - BLENDS

Shape U

Fig. 9 - Technology components J 26 Source: PM – Air-jet SpinningSource: Rieter

To be able to obtain the optimal spinning conditions in terms of yarn quality and running properties, various technology components are available. (Fig. 9)

9


The polyester/lyocell blend was manufactured in five different blend ratios by means of the draw frame blend. (Fig. 10) The yarn was spun with the air-jet and also with the ring spinning technology. The ring yarn gives the opportunity to compare the values achieved. Thus, with all blend variations, alongside the set objectives a direct comparison of air-jet to ring is possible to allow a better eval-uation of the results achieved.

Lyocell Polyester

Bale opener UNIfloc

SB draw frame SB draw frame

RSB draw frame RSB draw frame

Card Card

Air-jet

Roving frame

Ring

Blending – SB draw frame

Bale opener UNIfloc

Mixing bale opener Mixing bale opener

Post cleaner UNIstore

BlendPolyester 20% 33% 50% 67% 80%Lyocell 80% 67% 50% 33% 20%

Fig. 10 - Process line Source: TIS 27284 / Technology Process Analytics

4. Fiber Preparation Results

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The nep content in the sliver for the air-jet spinning process does not significant-ly differ after the last drafting passage between the different blend ratios of polyester and lyocell. With all blend ra-tios, it lies in the range of 4 - 6 neps/gram fiber material. (Fig. 11)

Conversely, with the ring spinning pro-cess a higher number of neps (10 neps/gram fiber material) at the last drafting passage was established in comparison to the air-jet spinning process. The cause is the higher fiber mass of 30 g/m in the drafting unit with the ring spinning pro-cess compared to 17.5 g/m in the last drafting passage with the air-jet spinning process. (Fig. 12)

With the fiber preparation for both air-jet spinning and ring spinning, it is appar-ent on the mixing draw frame that with a higher polyester ratio, the nep content increases.

The results clearly show that the sliver feed quality is considerably influenced by the fiber mass in the drafting unit and by the raw material.

To what extent a higher nep content of a respective raw material component is reproduced over the following process stages depends on the fiber mass in the drafting unit, the settings on the draw frame and the number of drafting pas-sages.

Nep

cont

ent [

1/g]

Nep

cont

ent [

1/g]

Process stages

Process stages

6055504540353025201510

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Nep Content over Process Stages - AFISPolyester/lyocell, 1.3 dtex, 38 mm, air-jet process

Nep Content over Process Stages - AFISPolyester/lyocell, 1.3 dtex, 38 mm, ring process

Fig. 11 - Fiber results

Fig. 12 - Fiber results

Source: TIS 27284 / Technology Process Analytics


Bale Card infeed Card sliver Blending Draw frame

Breaker Draw frame

Finisher Draw frame

Bale Card infeed Card sliver Blending Draw frame

Breaker Draw frame

Finisher Draw frame

100% CLY

100% CLY

20% PES/80% CLY

20% PES/80% CLY

33% PES/67% CLY

33% PES/67% CLY

50% PES/50% CLY

50% PES/50% CLY

67% PES/33% CLY 80% PES/20% CLY

80% PES/20% CLY67% PES/33% CLY

11


5. Further Improvement in Yarn Structure

The yarn tenacity decreases with the in-crease in delivery speed because of the wrapping fiber angle which becomes more flat. (Fig. 13) The yarn structure could, however, be significantly im-proved by injection of fluid in the yarn formation process. Using injection has a significantly positive influence on the fi-ber integration in the yarn bundle. The density of the yarn increases which re-sults in a higher fiber-fiber friction and therefore more strength. So the injection system increases the yarn tenacity up to 2.5 cN/tex, depending on the blend pro-portion.

The higher the polyester content and de-livery speed of the air-jet spinning ma-chine, the greater is the positive influ-ence of the injection.

Depending on the polyester content, by using injection the delivery speed resp. the production can be increased by ap-prox. 10% while maintaining the yarn strength.

Not only is the yarn strength positively influenced by injection, but also the elon-gation increases slightly due to injection by absolute 0.2%. (Fig. 14)

Consequently, using fluid injection must also positively affect the winding and abrasion resistance of the yarn with poly-ester or polyester-rich blends.

Tena

city

[cN/

tex]

Air-jet spinning delivery speed [m/min]

360 380 400 360 380 400 360 380 400 360 380 400 360 380 400

20% PES 33% PES 50% PES 67% PES 80% PES

80% CLY 67% CLY 50% CLY 33% CLY 20% CLY

28.027.527.026.526.025.525.024.524.023.523.022.522.0

Tenacity of Air-Jet Yarn vs Delivery Speed and Injection InfluencePolyester/lyocell, 1.3 dtex, 38 mm, Ne 40

Fig. 13 - Yarn quality Source: TIS 27284 / Technology Process Analytics

With injection Without injection

Elon

gatio

n [%

]

Air-jet spinning delivery speed [m/min]

360 380 400 360 380 400 360 380 400 360 380 400 360 380 400



9.00

8.75

8.50

8.25

8.00

7.75

7.50

7.25

7.00

Elongation of Air-Jet Yarn vs Delivery Speed and Injection InfluencePolyester/lyocell, 1.3 dtex, 38 mm, Ne 40


With injection Without injection

12


The yarn structure shows that the angle of the wrapping fiber increases with in-jection. (Fig. 15)

This creates more pressure on the paral-lel core fibers and results in a higher fi-ber-fiber friction and so more density and yarn strength. It means the effect of losing yarn strength with higher delivery speed can be partially compensated by injection.

The cause of the positive effect can there-fore be explained, that the fluid is imme-diately spread over the fiber surface with both polyester and viscose fibers. With cotton fibers as well as with “dewaxed” cotton fibers, the fluid initially remains as drops. The moistening of the fiber sur-face is therefore worse than with polyes-ter or viscose. (Fig. 16)

Whether and how far the moisture is ab-sorbed is not decisive for the fiber bond-ing. As far as a good moistening of the fiber surfaces is concerned, this has a positive effect on the fiber bonding where a higher bending rigidity of the fi-bers, as with polyester, is the case. That means the wrapping fiber angle becomes steeper. A better fiber bonding affects the following yarn values in a positive way:• mean tenacity • tenacity weakpoints • hairiness • winding and abrasion resistance

The following air-jet yarns in this study are all produced with injection.

Polyester / Lyocell, 1.3 dtex, 38mm, Ne 40

Cotton, Viscose, Polyester

With injection

Without injection

50% PES / 50% CLY

100% CO 100% CO (without Wax*) 100% CV

50/50% PES/CO 65/35% PES/CO 100% PES

*without Wax: CO Wax removed with Acetone

Fig. 15 - Air-jet Yarn Structure Source: TIS 27284 / Technology Process Analytics

Source: DITF DenkendorfFig. 16 - Wettability of raw material

13

16.0

15.5

15.0

14.5

14.0

13.5

13.0

12.5

12.0


6. Yarn Quality over the Blend Ratio Polyester and Lyocell

The ring yarn exhibits less unevenness than the air-jet yarn. (Fig. 17) From pre-vious studies we could already learn that in such a comparison between different yarn structures, the source of any differ-ences are not faults but mainly the indi-vidual yarn structures themselves. That is also the reason why there is no cor-relation between the unevenness values measured in the yarn on different yarn structures and the optical evenness in the fabric. The correlation between yarn and fabric unevenness is only given by using the same yarn structure.

Far more important for any process opti-mization is the awareness that uneven-ness increases with a higher polyester ratio in air-jet and ring yarn. This can be seen even in thin and thick places. (Fig. 18/19)

Thin and thick places are the main influ-encing parameter for unevenness. The reason is that with a more than 50% polyester ratio, the drafting force increas-es. Higher drafting force in a drafting unit is always a risk for uneven drafting work and therefore greater unevenness.

For such a study, the machine setting must kept constant as otherwise the in-fluence of the blend ratio cannot be seen and any changes of settings before would be a speculation and a risk.

Due to the winding process, the uneven-ness with ring yarn increases generally, depending on the raw material and wind-ing conditions. In that case and due to optimal friction points on the winding machine, there is only an increase of rel-atively less than 5% with ring yarn which is a normal value.



Mas

s var

iatio

n CV

m [%

]

Unevenness vs Blend Ratio on Air-Jet Yarn and Ring YarnPolyester/lyocell, 1.3 dtex, 38 mm, Ne 40


Air-jet Ring (cops) Ring (cone)

Blend proportion [%]



Thin

pla

ces -

40%

[n/1

000

m]

1 000

900

800

700

600

500

400

300

200

100

0

Thin Places vs Blend Ratio on Air-Jet Yarn and Ring YarnPolyester/lyocell, 1.3 dtex, 38 mm, Ne 40




14

600550500450400350300250200150100

500

700650600550500450400350300250200150100

500


The rise in thin places with increasing polyester content is the same on air-jet and ring when calculating in percentage.

The fine neps continually decrease with increasing polyester content in both air-jet and ring yarn (Fig. 20). In this respect, the decrease of these fine neps cannot be traced to the behavior of an individual end spinning process. The causes here are found in the greater fiber bending ri-gidity of polyester compared to that of ly-ocell. This means that the polyester has a lower tendency to nep formation due to the higher fiber bending rigidity. Howev-er, with the air-jet yarn structure, the sta-bility of the fiber bonding deteriorates. The fiber bonding in the yarn body can be verified with the “yarn windup test”. (Fig. 22)

The clear rise in fiber neps in the ring yarn due to the winding process shows that the neps in the ring yarn must have further causes than with air-jet yarn. On the ring yarn, fiber neps are formed pri-marily by fiber sloughing on the “ring traveler system” or by the rewinding pro-cess. This means that when considered in terms of the nep size/nep class (140% or 200%), the differences in absolute fig-ures between air-jet and ring yarn must be contrary.





Thic

k pla

ces +

35%

[n/1

000

m]

Neps

+14

0% [n

/1 0

00m

]

Thick Places vs Blend Ratio on Air-Jet Yarn and Ring YarnPolyester/lyocell, 1.3 dtex, 38 mm, Ne 40

Nep Content vs Blend Ratio on Air-Jet Yarn and Ring YarnPolyester/lyocell, 1.3 dtex, 38 mm, Ne 40

Fig. 19 - Yarn quality








15


In the coarse neps (Fig. 21) the air-jet yarn indeed shows fewer neps than the ring yarn. The coarse neps in the 200% classes have a lower mass increase with the periodically distributed wrapped fi-bers along the yarn axis than the slough-ing neps on ring yarn.

In other words, with the ring yarn struc-ture, the fiber neps which can primarily be formed by fiber sloughs are greater in their mass than the mass variants which are created by the yarn structure with air-jet yarn.

Thus, the number of coarse neps is high-er with ring yarns than with air-jet yarns. Consequently, more coarse neps must also be visible in ring yarn fabric than with air-jet fabric.

The following image (Fig. 22) shows a yarn roll tester developed by Rieter technology department. This measur-ing method serves to determine the fiber bonding tendency in the yarn body. The respective fibers are stretched in a car-riage and rolled as long from left to right on a defined fabric as the fiber breaks.



Neps

+20

0% [n

/1 0

00m

]110100

908070605040302010

0

Nep Content vs Blend Ratio on Air-Jet Yarn and Ring YarnPolyester/lyocell, 1.3 dtex, 38 mm, Ne 40

Yarn Roll Test for Air-jet Yarn


Fig. 22 - Yarn quality Source: Rieter




16

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Based on the previous positive results gained by an injection in the yarn for-mation process, it was recognized that the stability of the fiber bonding must be strongly dependent on the fiber bend-ing rigidity of the different raw materials. Therefore, the fiber bonding in the yarn body was more closely examined with different raw materials such as cotton, viscose and polyester. (Fig. 23/24/25)

From the raw materials tested, the high-est number of motion cycles was reached with cotton until the fiber broke. With viscose, fewer cycles were reached than with cotton.

As the measurement showed, the wind-ing resistance when using polyester ex-hibited the smallest number of motion cycles. The lower “bonding stability” in the yarn package with polyester fibers is due to the fiber bending rigidity.

The bending rigidity of the fibers thus in-fluences the bonding-friendliness of the fibers in the fiber package. Bend-rigid fi-bers consequently also inevitably reduce the yarn spinning limit. Fibers with high-er bending rigidity thus provide greater resistance to the twist insertion.

The bending rigidity of the fibers is made up of the elasticity module of the respec-tive raw material and the moment of in-ertia (fiber cross-section and fiber pro-file).

If the fiber characteristics are applied to the yarns and the textile end product, the advantage of a lower creasing tenden-cy occurs with a higher bending rigidity when processing polyester fibers.

380 m/min 450 m/min 450 m/min

6 bar 6 bar 5 bar


6 bar 6 bar 5 bar

Cycle

s to

yarn

bre

ak [n

]Cy

cles t

o ya

rn b

reak

[n]

70656055504540353025201510

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Cycles with Reversal point vs Delivery Speed and Spinning Air Pressure100% cotton, Ne 30

Cycles with Reversal point vs Delivery Speed and Spinning Air Pressure100% viscose, 1.3 dtex, 38 mm, Ne 30




0.5 cN/tex 2.5 cN/tex 5 cN/tex


17

3534333231302928272625242322


The rolling resistance of the yarns is therefore not to be confused with the yarn tenacity. The test shows that be-cause of the lower rolling resistance, the fiber bonding with polyester fibers in the air-jet spinning process is of major signif-icance for the yarn formation process and the piecing quality. In addition, from this it can be derived that with polyester the fiber bonding in the yarn body to avoid yarn thick places is of great importance.

The measuring results were, according to the raw material, strongly influenced by the delivery speed on the air-jet ma-chine and the yarn tension on the test de-vice. As long as the yarns in the woven or knitted fabric do not have a possibility to be wound by mechanical forces, no dis-advantages in the finished textile prod-uct also oppose this criterion. The results show, however, that by a suitable injec-tion in the fiber sun with air-jet spinning, a decisive step is achieved in significant-ly improving the yarn formation process when processing polyester fibers.

Due to the higher fiber-fiber friction in the yarn package the mean tenacity with ring yarns, depending on raw material blend, lies around 12 – 20% higher than with air-jet yarns. The fiber substance yield with ring yarns from the winder amounts to approx. 62% and with air-jet yarns approx. 52%.

With both end spinning systems, the mean yarn tenacity rises steadily with an increasing proportion of polyester as a result of the polyester’s higher fiber te-nacity. (Fig. 26)


6 bar 6 bar 5 bar

Cycle

s to

yarn

bre

ak [n

]70656055504540353025201510

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Cycles with Reversal point vs Delivery Speed and Spinning Air Pressure100% polyester, 1.3 dtex, 38 mm, Ne 30





Tena

city

[cN/

tex]

Tenacity vs Blend Ratio on Air-Jet Yarn and Ring YarnPolyester/lyocell, 1.3 dtex, 38 mm, Ne 40




18

25242322212019181716151413121110

12.011.511.010.510.0

9.59.08.58.07.57.06.56.0


It can be assumed that with ring yarns, a mean yarn tenacity of 16 cN/tex satis-factorily fulfills the requirements of the weaving running properties. With air-jet yarns, however, the mean yarn tenaci-ty should be higher in order to keep the yarn weak places in a range which pre-vents ends down in weaving.

Generally, it can be stated that the higher the mean yarn tenacity, the smaller the risk that the respective yarn weak plac-es will lead to an ends down. This state-ment can be justified by the fact that with the rise of the “mean tenacity”, normal-ly also the yarn weak places move out of the critical range where high thread ten-sion on the fiber leads to a break.

A key criterion for an adequate load bearing capacity in weaving is the warp. The warp yarn must be able to withstand the various stresses in the weaving pro-cess by means of sufficient tenacity and elongation, meaning by the yarn process-ability.

In this respect, the yarn weak places and the variation of the yarn tenacity play an equally decisive role. (Fig. 27) The yarn weak place should not lie below 100 cN and 2.5% elongation for warp and weft in the weaving application.

On the basis of air-jet yarn, a yarn count of Ne 40 (approx. 15 tex) and a blend of 20% polyester with 80% lyocell, a break force of up to 240 cN is still calcu-lated at a declared value for weak plac-es of 0.1%. The risk for a thread break is therefore small. Even at 0.05% of the measured values, the break force still lies at 220 cN.



Tena

city

(P 0

.1) [

cN/te

x]

Weak Points Tenacity vs Blend Ratio on Air-Jet Yarn and Ring YarnPolyester/lyocell, 1.3 dtex, 38 mm, Ne 40






Varia

tion

tena

city

cN/te

x [%

]

Variation Tenacity vs Blend Ratio on Air-Jet Yarn and Ring YarnPolyester/lyocell, 1.3 dtex, 38 mm, Ne 40




19


It is well known that a connection also exists between the break force variation and the ends down in weaving. To more closely observe the evaluation of yarn te-nacity variation, the explanation should be given that the variation of the yarn tenacity with ring yarns, produced from cotton, should not lie above 9%. The re-quirement in this case relates, however, to lower mean yarn tenacity. In practice, it is often attempted to keep the number of yarn weak places low by means of a minimal variation of tenacity. A higher variation of the break force of 9% thus does not mean in every case a higher ends down rate. What is more important is whether the weak places lie outside the range leading to an ends down.

With the different blends, the tenacity variation increases with a higher polyes-ter ratio, i.e. increasing fiber tenacity and therefore increasing “mean yarn tenaci-ty”, with both yarn structures. (Fig. 28). That means, the tenacity variation ris-es with a simultaneous increase of the mean yarn tenacity due to the change in raw material. With a high proportion of polyester, variation with air-jet yarn is approx. 11.5% and with ring yarn ap-prox. 10.5%.

In the distribution diagram of the “Te-nacity/Elongation”, a diagram according-ly emerges where an increasing polyester ratio primarily shows only a slimmer and longer drawn-out (ring yarn) area resp. a thicker and upward-shifting (air-jet yarn) area. (Fig. 29/30)

Tena

city

[N]

Tena

city

[N]

7

6

5

4

3

2

1

0

7

6

5

4

3

2

1

0

Distribution Tenacity / Elongation on Ring YarnPolyester/lyocell, 1.3 dtex, 38 mm, Ne 40

Distribution Tenacity / Elongation on Air-Jet YarnPolyester/lyocell, 1.3 dtex, 38mm, Ne 40

Peak load area

Peak load area

0

0

6

6

1

1

7

7

2

2

8

8

3

3

9

9

4

4

10

10

11

11

13

13

12

12

14

14

5

5





Ring yarn 80% PES/20% CLYRing yarn 20% PES/80% CLY

Air-jet yarn 80% PES/20% CLYAir-jet yarn 20% PES/80% CLY

Elongation [%]

Elongation [%]

20

12.011.511.010.510.0

9.59.08.58.07.57.06.56.05.55.0

6.26.05.85.65.45.25.04.84.64.44.24.03.83.63.43.23.02.82.62.4


The yarn weak points with air-jet yarns therefore only move very slowly out of the “danger zone” as a result of changing a raw material component. The variation of yarn tenacity as well as the “mean yarn tenacity” show that the weak places in the yarn can only be partially reduced by means of the raw material composition. An essential benefit is therefore offered by injection, to keep the number of weak places in the yarn low through better fi-ber bonding. The number of weak places in this particular application marginally differs from that of a ring yarn.

In particular with the air-jet yarn struc-ture, it should be attempted to optimize resp. ensure the number of undesired weak places and variation of the tenacity across the yarn formation process.

Alongside the fiber elongation, mean-ing the respective raw material, the yarn elongation is influenced by the yarn structure (fiber substance yield) and the level of yarn twist. (Fig. 31) Depending on the raw material and the yarn twist on ring yarn, a higher elongation results in favor of ring yarn than with air-jet yarn. With an increasing proportion of polyes-ter, the yarn elongation on ring yarn ris-es due to the higher fiber substance yield in contrast to air-jet yarn by an absolute figure of approx. 1%. Here, the ring yarn elongation shows an absolute figure of up to 1.8% higher than the air-jet yarn.

The high processability on both ring and air-jet yarn structures would very well fulfill the weaving requirements by means of the high yarn tenacity and elon-gation, even with the processing of sin-gle yarns. With a processability of air-jet yarns, which reaches 900 [cN cm] from tenacity and elongation, no problems are



Elon

gatio

n [%

]

Elongation vs Blend Ratio on Air-Jet Yarn and Ring YarnPolyester/lyocell, 1.3 dtex, 38 mm, Ne 40






Hairi

ness

H [-

]

Hairiness vs Blend Ratio on Air-Jet Yarn and Ring YarnPolyester/lyocell, 1.3 dtex, 38 mm, Ne 40




21

20

18

16

14

12

10

8

6

4

2

0


expected with high-performance weav-ing. As benchmark for the warp and weft processing, approx. 500 [cN cm] can be estimated for the required processabili-ty of the high-performance weaving ma-chines.

With an increasing proportion of polyes-ter, the hairiness with ring yarn becomes slightly reduced. (Fig. 32) Polyester fi-bers cause fewer fiber spreads than ly-ocell fibers at the spinning triangle fol-lowing the delivery roller pair of the ring spinning machine drafting unit. The re-winding process of ring yarn shows a far greater influence on hairiness than the polyester ratio. The hairiness with ring yarn significantly increases by approx. 23 – 24% due to the rewinding process.

With air-jet yarn, the two raw materi-al components have no influence on the hairiness in total. The hairiness is only influenced by the yarn structure. The air-jet yarn has, as was expected in this case, a clearly lower hairiness compared to ring cops (approx. 13 – 28%) and ring package (approx. 30 – 40%).

As also with the total hairiness, the lon-ger hairs of > 3 mm become slightly few-er with an increasing polyester ratio in ring yarns. (Fig. 33)

The rewinding process from cops to package has a clearly negative influence on the hairiness. With air-jet yarn, no hairiness of the longer fibers of > 3 mm can be detected.



Hairi

ness

S (>

3 m

m) [

1/m

]

Hairiness vs Blend Ratio on Air-Jet Yarn and Ring YarnPolyester/lyocell, 1.3 dtex, 38 mm, Ne 40




22


7. Influence of Plyed Air-Jet Yarn

Conventional ply yarns such as ring yarn have the following objectives: • increase strength• better running conditions in the down-

stream process• better evenness• high washing resistance• low pilling• soft drape• higher form stability

Depending on the type of manufacture, a distinction is made between two-ply and multiple ply yarns.

As in the case of yarns, the direction of twist is described by the letters S and Z. (Fig. 34)

The direction of twist of the ply yarn is usually opposite to that of the standard spun yarns.

Z

S

Z

Fig. 34 - Principle of ply yarn

Fig. 35 - Yarn structure

67/33% Polyester / Lyocell, 1.3 dtex, 38 mm

Ring Ne 40 αe 4.0

Ring Ne 40/2two-ply αe 3.6

Air-jet Ne 40/2two-ply αe 3.6

Air-jet Ne 40

The twist is described as loose, normal or hard, depending on the number of twists per unit of length.

The decision to use a two-ply yarn for air-jet and ring was made due to the applica-tion for suits or classical jackets.

The yarn structure of the single yarns for ring and air-jet as well as the yarns pro-cessed to twisted yarn is visible from the microscopic images. (Fig. 35) Here, the typical, far lower hairiness and the spe-cial structure of the fiber loops of air-jet single yarn compared to ring yarn can be easily recognized.

After the twisting process, the differenc-es between ring and air-jet yarn are only recognizable on closer inspection. Source: Rieter


23


7.1. Two-Ply Yarn Quality

Usually, the twist of the two-ply ring yarns is around 20 to 30% less than the spinning twist and is contrary to the twist direction with end spinning.

To determine the optimal twist for the two-ply air-jet yarn, the yarn characteris-tics were determined not only with a dif-ferent twist direction but also with a dif-ferent twist coefficient.

The greater the twist coefficient, the greater the twist contraction. Through the twist contraction, the yarn length is shortened and the yarn weight per length unit rises. In the case of an S-twist di-rection, the yarn coarsening resp. twist contraction amounts to 3 to 9% accord-ing to the twist coefficient. With a Z-twist direction, yarn coarsening due to the twist contraction amounts to 10 to 15%. (Fig. 36)

The twist contraction and therefore the fiber stress in the yarn are considerably higher with the Z-twist direction than with the S-twist direction. The higher stress on the fibers in the same twist di-rection with spinning as also with twist-ing (in that case, in the Z-direction) leads to excessive torsional loads in the yarn, which is obvious in a too high curling ten-dency of the twisted yarn.

Yarn

coun

t [Ne

]22

21

20

19

18

17

16

Yarn Count vs Twist Factor on Air-Jet Yarn67% polyester/33% lyocell, 1.3 dtex, 38 mm, Ne 40/2

Fig. 36 - Two-plyed yarn quality Source: TIS 27284 / Technology Process Analytics

"S" Twist "Z" Twist Expected two-ply yarn count Ne 20

Twist factor [αe]3.4 4.63.6 4.83.8 5.0 5.84.0 5.2 6.04.2 5.4 6.24.4 5.6 6.4

CVm twisted yarn =

CVm twisted yarn = – (a*αe)

Through the doubling of two yarns, as takes place in twisting, the yarn evenness im-proves by approx. 25 – 30%. (Fig. 37) The unevenness can be theoretically deter-mined by the mass increase from Ne 40 to Ne 20 after the “doubling principle”.

CVmE

CVmE * F

Number of doublings

Number of doublings

wherebyCVm E = unevenness on single yarn

According to the theoretical connection between evenness and the distribution of the tenacity through the doubling, an unevenness of 10.3 CVm would accordingly be cal-culated. The following results show that the unevenness is not only dependent on the single yarn and the number of doublings, but also on the twist direction and the twist coefficient αe.

Hence applies:

whereby Factor “F” with twist direction opposite to spinning direction = 1.19Factor “F” with twist direction same as spinning direction = 0.96Increase variable “a” with both twist directions = 0.35Twist coefficient English = αe

24


By applying the Z-twist direction, an im-proved unevenness, thin places and thick places was achieved compared to the S-twist direction. However, here the yarn exhibited a strong curling tendency. Ad-ditionally, it must be expected that the fi-ber stress is also too high. The question, whether the fibers and therefore the yarn are damaged by this will show up in the tenacity and elongation.

The thin places in the twisted yarn com-pared to single yarn have become mas-sively improved to such an extent that a change from -40 to -30% to a more sen-sitive fault class was made.

As was already recognizable with the un-evenness, the thin places (Fig. 38) and thick places (Fig. 39) with the Z-twist direction are considerably better than with the S-twist direction. Presumably the small irregularities are better “con-cealed” by the massive twist contraction (Z) than with a more expedient twist con-traction (S).

Mas

s var

iatio

n CV

m [%

]15.014.514.013.513.012.512.011.511.010.510.0

9.59.08.58.07.57.06.56.0

Unevenness vs Twist Factor on Air-Jet Yarn67% polyester/33% lyocell, 1.3 dtex, 38 mm, Ne 40/2


"S" Twist "Z" Twist Single yarn count Ne 40

Twist factor [αe]3.4 4.63.6 4.83.8 5.0 5.84.0 5.2 6.04.2 5.4 6.24.4 5.6 6.4

Thin

pla

ces -

30%

[n/1

000

m]

3 0002 8002 6002 4002 2002 0001 8001 6001 4001 2001 000

800600400200

0

Thin Places vs Twist Factor on Air-Jet Yarn67% polyester/33% lyocell, 1.3 dtex, 38 mm, Ne 40/2



Twist factor [αe]3.4 4.63.6 4.83.8 5.0 5.84.0 5.2 6.04.2 5.4 6.24.4 5.6 6.4

25


The neps (Fig. 40) also decline with in-creasing twist coefficient with S-twist. The twist contraction thereby conceals not only fine structural differences in the yarn but also fine fiber neps. With the Z-twist direction, the yarn is already so strongly twisted that even the influence exerted by the twist coefficient no longer has any effect on the yarn structure and any possible fine fiber neps. The suspi-cion of a too high fiber stress when using the same twist direction as the spinning direction, in other words the Z-direction, is confirmed.

The opposing S-twist direction to the Z-spinning direction clearly gave the highest tenacity values and thus lower stress on the air-jet yarn. It was already suspected with the curling tendency that the torsion forces in the twisted yarn were too high.

To keep the curling tendency as low as possible, the twist direction in this twist range – even with air-jet yarns – must be selected opposite to the spinning direc-tion.

Thic

k pla

ces +

35%

[n/1

000

m]

450

400

350

300

250

200

150

100

50

0

Thick Places vs Twist Factor on Air-Jet Yarn67% polyester/33% lyocell, 1.3 dtex, 38 mm, Ne 40/2



Twist factor [αe]3.4 4.63.6 4.83.8 5.0 5.84.0 5.2 6.04.2 5.4 6.24.4 5.6 6.4

Neps vs Twist Factor on Air-Jet Yarn67% polyester/33% lyocell, 1.3 dtex, 38 mm, Ne 40/2

Neps

+14

0% [n

/1 0

00m

]

4.0 5.0 6.04.8 5.83.6 4.4 5.4 6.43.8 4.6 5.63.4 4.2 5.2 6.2

400

350

300

250

200

150

100

50

0



Twist factor [αe]

26


The smaller the yarn twist coefficient the smaller the influence of the twist direc-tion on the tenacity. It clearly shows that already with a relatively small yarn twist, the greatest increase in tenacity takes place compared to single yarn. (Fig. 41)

The yarn twist should therefore be in the “opposite spinning direction” and be kept relatively low. The optimum for the gain in tenacity and thus for the lowest fiber stress can be expected at a value of ae 3.3.

In this respect, the same rule applies with air-jet yarn as with ring yarns. The twist in the yarn should counter the twist direction of the spinning process to avoid high torsional forces (loss of tenacity and curling tendency) in the twisted yarn.

Use of far lower twist coefficients than ae 3.3 in combination with the same twist-ed yarn and also spinning direction can offer the potential, according to the ba-sic conditions, to make the twisting pro-cess more productive. (Fig. 42) However, in the case of such a possibility, it must be observed that the tenacity of the air-jet single yarn is already optimally de-signed.

Where the spinning and twist direction was the same, further clarifications with a polyester/lyocell blend of 50/50 deter-mined a twist coefficient of ae 2.2. The measuring series clearly showed that the influence on the tenacity gain exerted by the twisted yarn process is greater than the influence exerted by the polyester ra-tio.

Tenacity vs Twist Factor on Air-Jet Yarn67% polyester/33% lyocell, 1.3 dtex, 38 mm, Ne 40/2

Tena

city

[cN/

tex]

4.0 5.0 6.04.8 5.83.6 4.4 5.4 6.43.8 4.6 5.63.4 4.2 5.2 6.2

31

30

29

28

27

26

25

24

23

22

21

20



Twist factor [αe]

Tenacity vs Twist Factor on Air-Jet Yarn50% polyester/50% lyocell, 1.3 dtex, 38 mm, Ne 40/2

Tena

city

[cN/

tex]

2.8 3.83.62.4 3.2 4.22.6 3.42.2 3.0 4.0

313029282726252423222120



Twist factor [αe]

27

2322212019181716151413121110

98


An overtwist in the air-jet yarn had an equally negative effect on the weak plac-es. The weakest yarn places lose tenacity as soon as the stress on the fibers in the yarn package exceeds a certain torsional force. (Fig. 43)

With the S-twist on the yarn, the weakest points could be increased up to a twist coefficient of ae 4.6 in the “weak points tenacity”, however at the expense of the “mean tenacity”. In this respect, it is rec-ommended not to twist with a higher twist coefficient than ae 3.3.

The same twist direction as the spinning direction, that is Z-direction, and the comparison with the single yarn show clearly that the twist factor at > ae 3.3 is in every case overtwisted.

By doubling two yarns, as is done with yarn twisting, the variation of the tenac-ity improves with S-twisted yarn by ap-prox. 38%. (Fig. 44) The tenacity varia-tion becomes reduced with increasing yarn mass and can, as with the uneven-ness, be theoretically determined ac-cording to the “doubling principle”.

Accordingly, a variation of the tenacity of 8% CVF was calculated.

Weak Points Tenacity vs Twist Factor on Air-Jet Yarn67% polyester/33% lyocell, 1.3 dtex, 38 mm, Ne 40/2

Tena

city

(P 0

.05)

[cN/

tex]

4.0 5.0 6.04.8 5.83.6 4.4 5.4 6.43.8 4.6 5.63.4 4.2 5.2 6.2



Twist factor [αe]

CVF twisted yarn =

CVF twisted yarn =

CVFE

CVFE * F

Number of doublings

Number of doublings

wherebyCVFE = variation of the tenacity on single yarn

As also with the unevenness, it became apparent that the actual variation of tenacity is also dependent on the twist direction, but not or hardly from the twist coefficient.

wherebyFactor twist direction = Fat twist direction opposite to spinning direction = 0.86at twist direction same as spinning direction = 1.15

28


Variation Tenacity vs Twist Factor on Air-Jet Yarn67% polyester/33% lyocell, 1.3 dtex, 38 mm, Ne 40/2

Varia

tion

tena

city

cN/te

x [%

]

4.0 5.0 6.04.8 5.83.6 4.4 5.4 6.43.8 4.6 5.63.4 4.2 5.2 6.2

121110

9876543210

Elongation vs Twist Factor on Air-Jet Yarn67% polyester/33% lyocell, 1.3 dtex, 38 mm, Ne 40/2

Elon

gatio

n [%

]

4.0 5.0 6.04.8 5.83.6 4.4 5.4 6.43.8 4.6 5.63.4 4.2 5.2 6.2

18.017.517.016.516.015.515.014.514.013.513.012.512.011.511.010.510.0

9.59.08.5 8.0

Fig. 44 - Two-plyed yarn quality

Fig. 45 - Two-plyed yarn quality





Twist factor [αe]

Twist factor [αe]

The elongation on the S-twisted yarn is massively better than on the single yarn, primarily due to the greater fiber mass of the yarn. (Fig. 45) The reason for the increase of yarn elongation with greater twist coefficient is found in the greater twist contraction resp. yarn length short-ening, which is shown by the tensile load before the ends down across the great-er change in direction for this. The same also applies, due to the higher twist con-traction, when the direction for both twisting and spinning is the same.

The yarn hairiness (Fig. 46/47) on the S-twisted yarn is around 50 – 60% high-er than with single yarn. With increasing yarn mass, the yarn hairiness is known to increase, as also with ring and rotor yarns. The reason is that the number of fibers in the cross-section resp. the yarn circumference is directly connected to the amount of the protruding fibers. With air-jet yarn with their relative low hair-iness, this also increases with coarser yarn. However, due to the very low hairi-ness with air-jet yarns, the increase must be far less strong with the coarsening of the yarn mass.

The biggest difference in hairiness from single yarn Ne 40 to the yarn count on the twisted yarn of Ne 20 (Ne 40/2) can therefore not be explained entirely by the increase of the bulk resp. number of fi-bers in the yarn cross-section. A signifi-cant part of the hairiness increase must be traced back to the adverse rewinding process. As far as hairiness is concerned, the advantages and disadvantages of a twisting process with air-jet yarn must be very carefully assessed.

29


The negative influence of the twisting process in respect of hairiness is all the greater, the smaller the yarn twist resp. the smaller the torsion forces (e.g. twist direction) are on the fibers. With increas-ing twist coefficient with twisting, the yarn hairiness decreases.

As already seen, this is nevertheless re-lated to the accordingly massive disad-vantage of a loss in tenacity.

An “overtwist” of the yarn, as is with the Z-twist, can in fact bring the hairiness to the level of the single yarn or even below. However, this is at the expense of the te-nacity and a too high curling tendency on the twisted yarn.

With the hairiness lengths of ≥ 3 mm, in all cases the hairiness was no longer measurable with twisted yarn.

Hairiness vs Twist Factor on Air-Jet Yarn67% polyester/33% lyocell, 1.3 dtex, 38 mm, Ne 40/2

Hairiness vs Twist Factor on Air-Jet Yarn67% polyester/33% lyocell, 1.3 dtex, 38 mm, Ne 40/2

Hairi

ness

S 1

+2 [1

/m]

Hairi

ness

H [-

]

4.0

4.0

5.0

5.0

6.0

6.0

4.8

4.8

5.8

5.8

3.6

3.6

4.4

4.4

5.4

5.4

6.4

6.4

3.8

3.8

4.6

4.6

5.6

5.6

3.4

3.4

4.2

4.2

5.2

5.2

6.2

6.2

1413121110

9876543210

6.5

6.0

5.5

5.0

4.5

4.0

3.5

3.0

2.5

2.0



Twist factor [αe]


Twist factor [αe]

"Z" Twist"S" Twist Single yarn count Ne 40

30


For the fabric production, a yarn twist co-efficient of ae 3.8 and a twist direction opposite to the spinning direction, that is “S”, was selected. According to the find-ings from the yarn results, however, a twist coefficient of ae 3.3 for the fabric production would have sufficed. (Fig. 48)

The running properties were faultless in the weaving preparation as well as in the weaving process. Operation was carried out without warp sizing. All weaving re-quirements were fulfilled. Spinning-relat-ed faults in the woven goods could not be identified in the scope of the trial. It can therefore be assumed that a first-class quality in the subsequent inspection can be achieved. As a guideline, 10 faults per 100 meter fabric will be accepted on in-spection of the fabrics, although usual-ly faults are distributed at a max. of 1/3 each between spinning, weaving and fin-ishing.

Fabric finishing with the lyocell-rich blend was made with prior merceri-sation and subsequent jigger dyeing. (Fig. 49) With the polyester-rich blends, a high-temperature jigger dyeing was carried out to avoid dyeing streakiness.

The appearance of the wool characteris-tic with the polyester/lyocell blend was achieved independently of the compo-nent ratios. (Fig. 50) The fabric design at-tained matches the typical applications of suiting materials or classical jackets as far as the optics are concerned. The fab-ric touch, however, is strongly dependent on the raw material and the yarn struc-ture and thus results in a unique touch for new and further textile applications.

WeavingApplication Woven fabric for suits

Warp and weft Two-plyed air-jet yarn Ne 40/2Warp per cm 46Weft per cm 27

Weaving construction 2/1 twillWoven weight 250 g/m²

Weaving Dornier rapierFilling insertion 600 U/min

Weaving PreparationWarping speed 1 100 m/min

Sizing No

Fig. 48 - Fabric finishing Source: TIS 27284 / Technology Process Analytic

Source: TIS 27284 / Technology Process Analytic Fig. 49 - Fabric finishing

Yarn Type

Blend ratio PES / CLY Finishing System

Air-jet 20% PES80% CLY

WashingMercerisation 30%

200° C FixationJigger

Resin finished

Lyocell dyed

Air-jet67% PES 33% CLY

WashingHT Jigger 130° C

Resin finishedPolyester dyedAir-jet 80% PES

20% CLY

Ring67% PES 33% CLY

8. Fabric Quality

31


Source: TIS 27284 / Technology Process AnalyticsFig. 50 - Fabric finishing

Ring 40/2, ae 3.8 67/33% PES / CLY

Polyester dyed

Air-jet Ne 40/2, ae 3.8 20/80% PES / CLY

Lyocell dyed

Air-jet 40/2, ae 3.8 67/33% PES / CLY

Polyester dyed

Air-jet 40/2, ae 3.8 80/20% PES / CLY

Polyester dyed

32

210

190

170

150

130

110

90

70

50

504846444240383634323028


8.1. Fabric Quality Greige

The measurements on the woven fabric were carried out on fabric of 5 cm width in raw white and finished condition, in order to also learn some of the important criteria regarding the influence of finish-ing on the fabric.

With an increasing proportion of polyes-ter up to 67%, the fabric breaking load in the weft and also in the warp direction significantly increases. Subsequently, through this fabric bonding, an increase of the breaking load due to an even high-er polyester percentage no longer exists. (Fig. 51/52)

The fabric breaking load with ring yarns is around 11% higher in the weft direc-tion and around 14% higher in the warp direction, due to the higher yarn tenaci-ty of 20%.

This means that lower yarn tenacity on air-jet yarn compared to ring yarn due to the fabric bonding will not necessari-ly be noticeable to the same extent in the fabric breaking load. The reason is that part of the lower air-jet tenacity is com-pensated by the yarn bonding in the fab-ric, resulting from the friction forces in the fabric.

Breaking Load vs Blend Ratio on Air-Jet Yarn and Ring YarnPolyester/lyocell, 1.3 dtex, 38 mm, Ne 40/2, woven fabric 2/1 twill, greige

Brea

king

load

[daN

]



20% PES 67% PES 80% PES

80% CLY 33% CLY 20% CLY

Fig. 51 - Fabric quality greige

Ring (warp) Ring (weft)Air-jet (weft)Air-jet (warp)

Tenacity vs Blend Ratio on Air-Jet Yarn and Ring YarnPolyester/lyocell, 1.3 dtex, 38 mm, Ne 40/2, woven fabric 2/1 twill, greige

Tena

city

[cN/

tex]



20% PES 67% PES 80% PES

80% CLY 33% CLY 20% CLY



33

34

32

30

28

26

24

22

20

18

16

14

55

50

45

40

35

30

25

20

15

10

5


The fabric elongation is an important cri-terion for the wearing comfort resp. the creasing tendency of suits or jackets. (Fig. 53)

It is well known that fabrics from man-made fiber, wool and silk exhibit better form stability than cotton. This is not least due to the higher fiber, yarn and thus also fabric elongation.

In the fabric weft direction, using air-jet yarn achieves the same elongation as when using ring yarn. On the contrary, measured in the warp direction air-jet yarn reaches a higher elongation than ring yarn and this despite the fact that the yarn elongation with air-jet single yarn is lower than with ring single yarn.

The plyed yarn twist in “S” direction with air-jet as well as with ring yarn was in both cases ae = 3.8.

On air-jet twisted yarn, a twist contrac-tion of 5% was shown and with ring yarn only 3.5%.

The elongation on air-jet and twisted ring yarn was 12%.

In this respect, the higher fabric elonga-tion in the fabric raw state in the weft di-rection with air-jet yarn can be explained by higher twist contraction.

Ultimately, the fabric characteristics af-ter the finishing process are decisive and qualify the influences of the spinning and twisting processes.

In total, the working capacity of the fab-ric with the 67/33 blend, manufactured from air-jet yarn, is the same as with ring yarn. (Fig. 54)

Elongation vs Blend Ratio on Air-Jet Yarn and Ring YarnPolyester/lyocell, 1.3 dtex, 38 mm, Ne 40/2, woven fabric 2/1 twill, greige

Elon

gatio

n [%

]

Work Capacity vs Blend Ratio on Air-Jet Yarn and Ring YarnPolyester/lyocell, 1.3 dtex, 38 mm, Ne 40/2, woven fabric 2/1 twill, greige

Wor

k ca

paci

ty [k

N.m

m]





20% PES 67% PES 80% PES

80% CLY 33% CLY 20% CLY

20% PES 67% PES 80% PES

80% CLY 33% CLY 20% CLY



Ring (warp)

Ring (warp)

Ring (weft)

Ring (weft)

Air-jet (weft)

Air-jet (weft)

Air-jet (warp)

Air-jet (warp)

34

210

190

170

150

130

110

90

70

50

504846444240383634323028


8.2. Fabric Quality Finished

With the finishing of the textile fabric, many positive characteristics such as touch, drape and optics of the goods can be obtained. The finishing can, depend-ing on raw material, unfortunately also negatively influence the breaking load resp. tenacity of the fabric. With an 80% lyocell proportion, the fabric tenacity can be approx. 10% lower due to the finish-ing process.

With an increasing or high polyester per-centage, however, no disadvantages in the fabric tenacity are created by finish-ing. (Fig. 55/56)

In this connection, with fabric develop-ment using new yarn structures and ac-cording to the raw material used, con-sideration must be given to how the chemical finishing can be adapted and clarifications made.

Breaking Load vs Blend Ratio on Air-Jet Yarn and Ring YarnPolyester/lyocell, 1.3 dtex, 38 mm, Ne 40/2, woven fabric 2/1 twill, finished

Brea

king

load

[daN

]

Tenacity vs Blend Ratio on Air-Jet Yarn and Ring YarnPolyester/lyocell, 1.3 dtex, 38 mm, Ne 40/2, woven fabric 2/1 twill, finished

Tena

city

[cN/

tex]



20% PES 67% PES 80% PES

80% CLY 33% CLY 20% CLY

Fig. 55 - Fabric quality finished




20% PES 67% PES 80% PES

80% CLY 33% CLY 20% CLY



35

34

32

30

28

26

24

22

20

18

16

14

55

50

45

40

35

30

25

20

15

10

5


The elongation (Fig. 57) in the fabric in-creases over the finishing process in the weft direction and decreases in the warp direction and therefore no clear behav-ior can be recognized during the finish-ing process.

The working capacity (Fig. 58) shows no clear influence exerted by the finishing process. The working capacity rises with an increasing polyester proportion. Af-ter the finishing process, the working ca-pacity of the fabric manufactured from ring yarn is approx. 15% higher than that manufactured from air-jet yarn. The cause can be found in the higher yarn working capacity of twisted ring yarn.

Elongation vs Blend Ratio on Air-Jet Yarn and Ring YarnPolyester/lyocell, 1.3 dtex, 38 mm, Ne 40/2, woven fabric 2/1 twill, finished

Elon

gatio

n [%

]



20% PES 67% PES 80% PES

80% CLY 33% CLY 20% CLY



Work Capacity vs Blend Ratio on Air-Jet Yarn and Ring YarnPolyester/lyocell, 1.3 dtex, 38 mm, Ne 40/2, woven fabric 2/1 twill, finished

Wor

k cap

acity

[kN.

mm

]



20% PES 67% PES 80% PES

80% CLY 33% CLY 20% CLY



36

6

5

4

3

2

1

0

6

5

4

3

2

1

0


With the blend with a 67% polyester com-ponent, the pilling values (Fig. 59/60) give the same result with the twisted ring yarn as with air-jet yarn. Here, the mas-sive influence of twisting on the pilling values is apparent. It can thus be seen that the positive influence of twisting on the pilling characteristics is greater than the influence of the different yarn struc-ture of single yarns. The pilling values of air-jet yarn also show that this is not in-fluenced by the blend composition.

The pilling values are therefore positive-ly influenced in the following sequence:

1. twisting process2. yarn structure3. raw material

Pilling Grade on Air-Jet Yarn and Ring YarnPolyester/lyocell, 1.3 dtex, 38 mm, Ne 40/2, woven fabric 2/1 twill, finished

Grad

e

125 500 1 000 2 000 5 000 7 000

Pilling Grade on Air-Jet Yarn vs Blend RatioPolyester/lyocell, 1.3 dtex, 38 mm, Ne 40/2, woven fabric 2/1 twill, finished

Grad

e

125 500 1 000 2 000 5 000 7 000



Cycles

Cycles



67% PES/33% CLYRing

20% PES/80% CLYAir-jet




37


The yarn manufacturing costs were cal-culated for Indonesia (Fig. 61) and Chi-na (Fig. 62) based on the selected spin-ning schedule which was determined in the trial.

The manufacturing costs of air-jet yarns do not differ with the two countries In-donesia and China. Conversely, with ring yarns and the higher personnel intensity involved, the costs in China are minimal-ly higher than in Indonesia.

The manufacturing costs of ring yarns are approx. 33% higher in Indonesia and 35% higher in China than that of air-jet yarns.

With an increasing proportion of poly-ester, the manufacturing costs decrease minimally.

One reason is the waste costs on the cards. These are with 100% polyester 0.6% and with 100% lyocell 1.5% calcu-lated waste.

With air-jet yarn, the yarn manufacturing costs play a lesser role despite the low-er waste costs with an increasing lyocell percentage. The reason is that with air-jet spinning, slightly higher investment costs for the injection equipment are cal-culated from a polyester ratio of 50%.

CLY[%]PES [%]

Euro

/kg

1.00

0.90

0.80

0.70

0.60

0.50

0.40

0.30

0.20

0.10

0.00

Yarn Manufacturing Cost for ChinaPolyester/lyocell, 1.3 dtex, 38 mm, Ne 40

80 67 50 33 20 80 67 50 33 20 20 33 50 67 80 20 33 50 67 80

Cost of waste Labor costs Energy costs Cost of auxiliary Capital costs

Euro

/kg

1.00

0.90

0.80

0.70

0.60

0.50

0.40

0.30

0.20

0.10

0.00

Yarn Manufacturing Cost for IndonesiaPolyester/lyocell, 1.3 dtex, 38 mm, Ne 40

80 67 50 33 20 80 67 50 33 20 20 33 50 67 80 20 33 50 67 80

Air-jet

Air-jet

Ring

Ring

Cost of waste Labor costs Energy costs Cost of auxiliary Capital costs

CLY [%]PES [%]



Fig. 61 - Economy

Fig. 62 - Economy

9. Economy

38


10. Summary

The analysis showed the influences and properties of yarn and fabric with poly-ester-lyocell blends in air-jet spinning for weaving applications.

10.1. Single Yarn

• Using the new injection technology, the yarn formation process is positive-ly influenced. The tenacity, rolling resis-tance and abrasion resistance can thus be massively increased using polyester or polyester-rich blends.

• Weak places in the yarn can only be min-imally changed by means of the raw ma-terial blending ratio. The primary aim must be to optimize across the yarn for-mation process any undesired tenacity weaknesses or variation values for te-nacity and elongation.

• The measured unevenness of air-jet yarns is higher compared to ring yarns. With an increasing proportion of poly-ester, the unevenness independent of yarn structure increases. The uneven-ness values include the influence of the yarn structure and can therefore not be comparably evaluated in absolute terms.

• The yarn neps gradually reduce with an increasing proportion of polyester in both yarn structures. If the measur-ing range for air-jet yarn applies to the coarser neps class, then air-jet yarn clearly shows better values than ring yarn.

• Compared to cotton and man-made fi-ber cellulose, polyester is more difficult to bond in the fiber bundle.

• Due to the higher fiber-fiber friction in the yarn, the mean strength with ring yarns, depending on the raw materi-al blend, is approximately 12 – 20% higher.

• With the air-jet yarn structure, the num-ber of undesired weak places and the variation in tenacity across the yarn for-mation process must be ensured, where necessary. This cannot be achieved by means of the polyester ratio.

• Air-jet yarn shows a significantly lower hairiness than ring yarn, in this case ap-proximately 13 – 28%.

10.2. Two-Ply Yarn

• The twisting process shows clear advan-tages with air-jet yarns of better even-ness and tenacity.

• The optimal twist for air-jet yarn be-comes apparent with a twist coefficient of ae 3.3 and the opposite twist direc-tion to the spinning direction. The same twist as spinning direction enables the possibility of using a very low two-plyed twist factor and therefore cost reduction in the twisting process.

10.3. Weaving and Fabric

• The running properties in the weaving preparation as well as in weaving ma-chine were faultless.

• The weaving process could be made without any sizing.

• With an increasing polyester ratio up to 67%, the fabric break load in the weft as well as in the warp direction substantial-ly increases. Subsequently, due to the fabric bonding with an increasing poly-ester ratio, there is no further significant increase in the break load.

• With 80% lyocell ratio, the fabric tenac-ity can be around 10% lower due to the finishing process. With an increasing or high polyester ratio, however, there are no disadvantages in the fabric tenacity caused by finishing.

• The positive influence of the twisted yarn in terms of fabric pilling character-istics is greater than the yarn structure of the single yarns.

• The pilling characteristics are influenced by the following ranking:1. twisting process2. yarn structure3. raw material

10.4. Economy

• The manufacturing costs of ring yarns are approximately 33% higher in the case of Indonesia and around 35% high-er for China than those of air-jet yarns.

• With an increasing proportion of poly-ester, the manufacturing costs decrease minimally. One of the reasons is found in the waste costs on the cards. These are with 100% polyester 0.6% and with 100% lyocell with 1.5% calculat-ed waste.

• With air-jet yarn the yarn manufacturing costs show no difference with increas-ing polyester content, despite the lower waste costs using polyester because of the investment for a new technology fa-cility like injection.

39


Rieter India Private Ltd.Gat No. 768/2, Village WingShindewadi-Bhor RoadTaluka Khandala, District SataraIN-Maharashtra 412 801T +91 2169 304 141F +91 2169 304 226

Rieter Machine Works Ltd.Klosterstrasse 20CH-8406 WinterthurT +41 52 208 7171F +41 52 208 [email protected] [email protected]

www.rieter.com

The data and illustrations in this brochure and on the corresponding data carrier refer to the date of printing. Rieter reserves the right to make any necessary changes at any time and without special notice. Rieter sys-tems and Rieter innovations are protected by patents.

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Rieter (China)Textile Instruments Co., Ltd.Shanghai BranchUnit B-1, 6F, Building A,Synnex International Park1068 West Tianshan RoadCN-Shanghai 200335T +86 21 6037 3333F +86 21 6037 3399

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