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Encyclopedia of twisted yarn

Twisting mill RUOSS-KISTLER AG, twisted yarn encyclopedia; twisting term simply explained

 What exactly is a twisted yarn?
 Why twist yarn?
 Different kinds of twisted yarns
 Numbering system (fineness)
 Conversion table
 Specification (of a twisted yarn) 
 Manufacture (of a twisted yarn)
 Process (of a twisted yarn)
 Ply twist table (of a twisted yarn)
 Rotation coefficient (alfa)

 


 

What exactly is a twisted yarn?

A twisted yarn is the result of twisting two or more yarns together.

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Why twist a yarn?

Why don't you take a thicker yarn instead of twisting two yarns together? This would not cost as much!

A two-fold twisted yarn has, depending on construction, not only approximately 20 per cent more tensile strength and more extension than the two single yarns together, but even more than the equivalent thicker single yarn. 
The twisted yarn and the fabrics which have been produced out of it, are more even. 
The twisted yarn, which is made by a normal twist, is more voluminous, that means, the produced fabrics are better covered. 
With a twisted yarn a softer and pleasant fabric feel will be obtained. 
Fabrics made of twisted yarns are more durable and resistant to chaffing. 
With a twisted yarn a higher dimensional stability of the end-product will be achieved. 
With special twisted yarns a specific effect and character can be achieved. 
The twisted yarn has better running characteristics in the subsequent processing and allows a higher efficiency rate. 
A normal twisted yarn produces less curl than a single yarn (reduction of the inner torque).

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Different kinds of twisted yarns

A "normal" twisted yarn (poplin) is made from two single yarns, which are twisted in Z direction. The twisted yarn itself will be twisted in the S direction. The rotation of this twisted yarn is more or less a single yarn twist and the result is, that the fibres will once again lie parallel to the twist axis.

z / S twisted yarn

The possibility of variation lies in the amount of the spun fibres as well as in the amount of the twist rotation. The optimum characteristics of the products can be  brought out in this way. Stronger twists for weaving mills and softer ones for knitting mills are the general rule.

The sewing thread is normally made of three S-twisted single yarns, which are twisted together in the Z direction.

s / Z twisted yarn (sewing thread)

A tear-resistant thread with a round transverse section will thus be created.

The voile is produced from a spun fibre which is twisted in Z direction. The special thing is, that the twisted yarn is also twisted in the same direction, as the spun fibre (z direction). A hard twisted yarn is the result, with a tendency to curl. The fabric made from it, will be transparent, robust in grip. Curtains were often produced from it years ago. To get a higher transparency and also to produce luminous colours the finished twisted yarn has to be gassed. This means that the fibres which stick out are burnt off.

z / Z twisted yarn (voile)

Very highly twisted yarns are called crêpe twists.

 

Fancy twists or nub yarns are twisted yarns which are made from different kinds of components such as nub, loop and other effects and are produced on special machines.

 

Special constructions are multiple and multi stage twisted yarns, which are in praxis of little consequence due to the price factor.

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Numbering system (fineness)

The fineness of cotton yarns can be expressed essentially in three systems.

 metric number Nm
 English number Ne
 tex-system

Nm and Ne are length numbers, this means, the fineness will be defined by the length, the result will be a specific weight.

Nm declares which length weighs 1kg (for example Nm100: 1kg is 100km long).

Ne declares how many times 840 Yards (1 Yard = 0.9144m) makes 1 English pound (0.45359kg) (for example Ne 60: 1 English pound is 60*840=50'400 Yards (=46,08576 km)

The official tex-system, which up to now has not really caught on, is a weight numbering system, this means, the fineness is defined by the weight, which a specific length of the yarn has.

tex means, how many grams does 1 km of a yarn weigh. (for example 10 tex:1 km weight 10 gr).

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Conversion table

Nm = 1.69336*Ne Nm = 1000/tex
Ne = 0.590541*Nm Ne = 590.541/tex
tex = 1000/Nm tex = 590.541/Ne

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Specification

The specification of a twisted yarn can be better illustrated by an example:

Nm 100/2 z1000 / S800 (short cut Nm100/2)

Nm = metric numbering system
100 = yarn number of the single yarn (100 km/kg)
/2 = it is a two-fold twisted yarn (made of two components)
z1000 = the single yarn is twisted with 1000 rotations per m in z-direction
S800 = the twisted yarn is twisted with 800 rotations per m in s-direction

 

Ne 60/2 z25 / S20 (short cut Ne 60/2)

Ne = English numbering system
60 = yarn number of the single yarn
/2 = it is a two-fold twisted yarn (made of two components)
z25 = the single yarn is twisted with 25 rotations per inch in z-direction
S20 = the twisted yarn is twisted with 20 rotations per inch in s-direction

 

20 tex z600 x 2 S400 (short cut 20 tex x 2)

20tex = the tex-system; the number is 20 (20gr/km)
z600 = the single yarn has been spun with 600 rotations per m in z-direction
x2 = it is a two-fold twisted yarn
S400 = the twisted yarn is twisted with 400 rotations per m in s-direction

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Manufacture

The twisting and post treatment takes place in several stages. First two (or more) threads on a doubling bobbin come together.

doubling  Doubling

 

This operation can also be made on the twisting machine, where the twisted yarn is very coarse. After that the actual twisting process follows by twisting two (or more) threads together.

twisting Twisting

 

To produce more gloss and to avoid pilling, the fibres, which protrude after the twisting process, can be burnt off.

gassing   Gassing

Finally you can wind the package to remove the dust, to apply wax or just to get the required package format.

A specialty of the company RUOSS-KISTLER AG is the combination of the doubling and gassing processes. With this combination it is possible to get an almost dust free twisted yarn.

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Process

In the area of cotton yarns there are three main types of twisting processes.

Two-for-one twisting
Terrace twisting / Tritec) 
Ring twisting

Two-for-one twisting  is the most common twisting process in our field. In this process the twisted yarn gets two ply twists with just one spindle turn.

two for one spindle               two for one twisting machine
Two-for-one spindle                                                 Two-for-one twisting machine

back to process             

 

The process of terrace twisting or tritec  is mostly employed in the coarse counts and is used in special areas.

 tritec spindleTritec-Spindle

back to process              

 

The ring twisting process is still only meaningful for nub yarn production. It would be very profitable, but for quality reasons (too many knots in the twisted yarn) hardly used any more.

Had a way been found to replace the knots with a perfect twisting connection (splice), a renaissance of the ring twisting machine would not be impossible.

back to process         top


Ply twist table (of a twisted yarn) (not binding standard data)

Nm

Weaving

Knitting

 

Ne

Weaving

Knitting

T/m T/m tex  

T/i

T/m

T/i

T/m

tex

30/2

470

440

33.3 x2

 

20/2

12.7

500

11.7

461

29.5x2

40/2

540

510

25.0x2

 

30/2

15.6

614

14.4

567

19.7x2

50/2

610

570

20.0x2

 

40/2

18.0

709

16.6

654

14.8x2

60/2

670

620

16.7x2

 

50/2

20.1

791

18.6

732

11.8x2

70/2

720

670

14.3x2

 

60/2

22.0

866

20.3

799

9.8x2

80/2

770

720

12.5x2

 

70/2

23.8

937

21.9

862

8.4x2

90/2

820

760

11.1x2

 

80/2

25.4

1000

23.5

925

7.4x2

100/2

860

800

10.0x2

 

90/2

27.0

1063

24.9

980

6.6x2

110/2

900

840

9.1x2

 

100/2

28.4

1118

26.2

1031

5.9x2

120/2

940

880

8.3x2

 

110/2

29.8

1173

27.5

1083

5.4x2

130/2

980

910

7.7x2

 

120/2

31.1

1224

28.7

1130

4.9x2

140/2

1'020

950

7.1x2

 

130/2

32.4

1276

29.9

1177

4.5x2

150/2

1'050

980

6.7x2

 

140/2

33.6

1323

31.0

1220

4.2x2

160/2

1'090

1'010

6.3x2

 

150/2

34.8

1370

32.1

1264

3.9x2

170/2

1'120

1'040

5.9x2

 

160/2

36.0

1417

33.2

1307

3.7x2

180/2

1'150

1'070

5.6x2

 

170/2

37.1

1461

34.2

1346

3.5x2

190/2

1'190

1'100

5.3x2

 

180/2

38.1

1500

35.2

1386

3.3x2

200/2

1'220

1'130

5.0x2

             

210/2

1'250

1'160

4.8x2

             

220/2

1'280

1'190

4.5x2

             

230/2

1'300

1'210

4.3x2

             

240/2

1'330

1'240

4.2x2

             

250/2

1'360

1'260

4.0x2

             

260/2

1'390

1'290

3.8x2

             

270/2

1'410

1'310

3.7x2

             

280/2

1'440

1'340

3.6x2

             

290/2

1'460

1'360

3.4x2

             

300/2

1'490

1'390

3.3x2

             

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Rotation coefficient (alfa)

The twist of a doubled yarn depends on the twist number. The rotation coefficient (alfa) determines the hardness of a twisted yarn.

The formula for the corresponding numbering-system:

 
tex-system
 

Nm

Ne

 
alfa tex = T * tex½
 

alfa m = T / Nm½

alfa e = T / Ne½

T = twist rotation per m
tex = Number in tex

T = twist rotation per m
Nm = metrics twist number

T = twist rotation per inch
Ne = English twist number

 

Examples of  rotation coefficient:

  soft medium hard
alfa tex 3100 3800 5700
alfa m 100 125 180
alfa e 3.25 4 6

 

Conversion:

alfa tex =   alfa m * 31.6

alfa tex =   alfa e * 957

alfa m =   alfa e * 30.3

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