Description, Designation and Annotation of Textile Yarn

There is frequently a need to describe the textile yarn concisely in the language which a laymen can understand. Also there is a need to write concisely the description of the textile yarn. ASTM has an elaborate system to describe spun, filament and a yarn made from a combination of these i.e. ply and cable yarn. 

In yarns such as ply or cable yarn which are made from components, it is essential to describe the components and the resultant from those components. Thus in describing such yarns, there have to be two groups; one of them describes the components and the other describes the resultant yarn. Accordingly there are two ways to write a yarn description. 

First method is called single to fold or ply notation. In this system, the single component of yarn is described first and only then the resultant yarn is descibed. This system is used in indirect numbering system. 

Second method is called fold or ply to single notation. In this system, the whole structure is described first and then the components are described. This is frequently used by yarn buyers. 

The full treatment of the topic is given here. Some general guidelines and examples are given in this article.

The notation 

24 Ne Z 15tpi (Cotton, 1 1/6 inch, SLM, 4.3 Micronaire Reading)/5 S 9 tpi/3 Z 5tpi; R 1.4 cc

represents a yarn made from 24 Count twisted in z direction with 15 twists per inch which is then again twisted 5 fold in s directions with 9 tpi and three such yarns are again twisted in Z direction with 5 tip which give a resultant cotton count of 1.4. 

The filament single yarn is described as

11 tex f40 s 2.5tpi( nylon 2.5 dtex)

For yarns where linear density gets increased on bulking or texturising, we describe it by symbol B.

70 den f34 t0(Nylon 2.97den); B 80 den

B 80 indicate that the denier of yarn is increased from 70 to 80 after bulking. 

Multiple wound yarns are described as:

25 tex Z 15 tpi ( Cotton ) x 2 t0

Here t0 indicate zero twist and describes that 2 yarns of 25 tex cotton with 15 tpi in z direction are wound together.

We can also describe a yarn using x.

You can read more here.

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Influence of Fiber Fineness and Maturity in spinning Process

Influence of Fiber Fineness and Maturity on spinning Process

Fiber Fineness

Fiber fineness determine how many fibers are present in the cross section of a yarn of given thickness. Additional fibers in the cross section not only provide additional strength but also a better distribution in the yarn. Minimum 30 fibers are needed, usually over 100 fibers are required. Fiber fineness influences spinning limit, drape of the fabric, yarn strength, luster, yarn evenness, handle, yarn fullness and productivity. Productivity is influenced by reduced end breakage rate.

In a conventional spinning process, fine fibers accumulate to the core and coarse fibers in the periphery.

Fiber fineness is measured in dtex which is equal to ratio of mass in dgrams and length in km. Decitex is equal to the product of Micronaire value of the cotton and 0.394.

Cotton fibers are generally classified as very fine if they have a micronaire value upto 3.1; fine if they have value between 3.1 to 3.9; medium if they have it between 4.0 to 4.9; slightly coarse between values of 5 to 5.9 and coarse if they have a micronaire value above 6.

Fiber Maturity

Cotton fiber consists of cell wall and lumen. The maturity index depends upon the thickness of the cell wall. The fibers are considered ripe if they have maturity index between 50-80 percent, unripe if they have MI between 30 to 45% and dead when they have it less than 25%.

Unripe fibers have neither adequate strength nor adequate longitudinal thickness. They lead to loss of yarn strength, neppiness, high proportion of short fibers, varying dyeability, processing difficulties mainly at the card.

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Why Fiber Fineness is so Important

Why Fiber Fineness is So Important

It has been known since long that fiber fineness plays an important role in determining the quality of resultant yarn and hence that of the resultant fabrics. In general fiber fineness is important due to the following factors:

1. It affects Stiffness of the Fabric

As the fiber fineness increases, resistance to bending decreases. It means the fabric made from yarn of finer fiber is less stiff in feel. It also drapes better.

2. It affects Torsional Rigidity of the Yarn

Torsional rigidity means ability to twist. As fiber fineness increases, torsional rigidity of the yarn reduces proportionally. Thus fibers can be twisted easily during spinning operation. Also there will be less snarling and kink formation in the yarn when the fine fibers are used.

3. Reflection of Light

Finer fibers also determine the luster of the fabric. It is so because they there are so many number of fibers per unit area that they produce a soft sheen. This is different from Hard glitter produced by the coarser fibers. Also the apparent depth of the shade will be lighter in case of fabrics made with finer fibers than in case of coarser fibers.

4. Absorption of Dyes

The amount of dye absorbed depends upon the amount of surface area accessible for dye out of a given volume of fibers. Thus finer fibers leads to quicker exhaustion of dyes than coarser fiberes.

5. Ease in Spinning Process

Finer fibers leads to more fiber cohesion because the number of surfaces are more so cohesion due to friction is higher. Also finer fibers lead to less amount of twist because of the same increased force of friction. Which means yarns can be spun finer with the same amount of twist as compared to coarser fibers. Which also means that the yarns will be softer.

6. Uniformity of Yarn and Hence Uniformity in the Fabric

Uniformity of yarn is directly proportional to the number of fibers in the cross fibers. Hence finer the fiber, the more uniform is the yarn. When the yarn in uniform lit leads to other desirable properties such as better tensile strength, extensibility and luster. It also leads to fewer breakages in spinning and weaving. In fact fiber fineness is one of the dominant factor in determining the limiting count to which a yarn can be spun.

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Vendor Rating for Yarn Supplier for Denim

For 7s count

Evaluated at the end of 6 months

Weightage



Quality=50%,Price=30%,Delivery= 20%


I. Quality

CSP
>1900=4, 1800-1899=3, 1700-1799=2, 1600-1699=1, <1599=0>Count CV
0-2.5=2, >2.5=0,

Imperfections( /1000m)

a. Thin places
0-2=5, 3-10=2, >10=0

b. Thick Places
<10=5, 40="2,">40=0

c. Neps
0-2=5, 3-6=2, >6=0

Classimate Results

a. Analysis for total faults

<10=4, 30="2," 50="1,">50=0

b. Analysis for Objectionable Faults(A4, B4, C3, C4, D3, D4)

0-2=4, 3-4=2, >4 =0

Weightage in Quality

CSP=20%, Count CV=20%, Imperfections( Thin=10%, Thick=10%, Neps=10%), Classimate ( Total Faults=10%, Objectionable Faults=20%)

II. Delivery Schedule

100% Compliance=5, 90-99%=4, 80-89%=3, 70-79%=2, 60-69%==1, <60%=0

III. Prices

They are determined on a 5-point basis.

Total

>3.8--> Excellent, 3.0-3.8-->Good, 2.0-3.0-->Average, <2-->Poor

Notes on Yarn for Rope Dyeing in Denim

Notes on Yarn for Rope Dyeing

* Yarn faces stress and stretch at ball warping, rope dyeing, rebeaming, sizing and loom shed so elongation of yarn should be more than stretch at (ball warping + Robe Dyeing+ Rebeaming + Sizing )= (2-3%) + Loom shed (about 5%)

* Tension at Ball warping should be less by 7-8% of single yarn strength.

* Strength CV should be within limits as it may give rise to weak points

* The tendency of yarn to migrate at rope dyeing can be countered by less micronaire of yarn ( should be around 3.8-4.2)

* More dropping of short fibers at long chain beaming is good

*The sensitivity settings for neps is set at +280 for rotor spun yarn and not +200 as in case of ring spun yarn. The reason for this is that the structure of rotor spun yarn is intrinsically different from that of conventional ring spun yarn. Neps in rotor yarn tend to be spun into the solid yarn body rather than remaining on the yarn surface, which is typical of ring spun yarns. Although embedded in the yarn core, these neps still represent a short mass defect and will therefore trigger the imperfection counter upon exceeding the preset value. However, compared to neps that are attached to the yarn surface, fully embedded neps are barely perceptible for the human eye. Thus, in order to balance the typical visual appearance of rotor spun yarn with the imperfection counts, +280 sensitivity setting is a common convention for rotor spun yarns.

Comparison of Ring Yarn with OE yarn at Ne 7