Classification and structural characteristics of yarn

Yarn is a collective term for yarn and thread, a thin and soft continuous strip made of textile fibers with a certain thickness and physical and mechanical properties. Including yarn, thread and filament etc.

There are many types of yarns. According to different starting points, yarns can be classified.

Classified by fiber composition



Based on fiber composition

(1) Pure spun yarn

Yarn, silk, thread spun from a kind of fiber or polymer with constant composition, such as cotton yarn, wool yarn, viscose yarn, etc.

(2) Blended yarn

Yarns, silks and threads made of two or more fibers blended or spun or plied, such as: polyester 65/cotton 35, polyester 50/cotton 33/nylon 17

(3) Accompanying spinning yarn

Yarn spun from soluble fibers (short fibers or filaments) and short fibers.



According to the distribution of mixed fibers

(1) Evenly mixed yarn

Consists of uniformly mixed spinning, spinning or plying of fibers of different fiber components or different colors and different properties;

(2) Varying mixed yarn

Yarns with different fiber components or different colors and different properties in the yarn body with a gradual or abrupt distribution of fibers, such as gradual color yarns, slub yarns

(3) Combined or composite yarn

Yarn, silk, thread composed of short fiber and short fiber, short fiber and filament, filament and filament, fiber bundle and yarn, etc., such as core-spun yarn, wrapping yarn, etc.



2 According to the use of yarn classification

Processing yarn

(1) Yarn for fabric main body

Weaving yarn: it is divided into warp yarn and weft yarn. The warp yarn requires higher strength and twist, and is often thread; the weft yarn requires lower strength and is softer;

Knitting yarn: uniform thickness, knots and thick, few details;

Yarn for knitting: high strength, smoothness and good elasticity

(2) Fabric auxiliary yarn

Raising yarn, stitching yarn, backing yarn or filling yarn, etc.



Finished yarn

Such as tire cord, sewing thread, etc.



3 other categories

Twisting directions are called S twisted yarn and Z twisted yarn respectively; waste silk, waste silk, waste yarn, spliced ??yarn, etc.; bobbins, cheese, hank yarn; primary color yarn, bleached yarn, dyed yarn, singeing yarn, mercerized yarn, etc. .



2 Processing and development of yarn



1 Basic principles of yarn processing



1 Processing of spun yarn

-Fiber opening (removal of impurities and mixing) → carding into a web → slivering → drawing and mixing → drafting and twisting → yarn formation → package forming

2 Processing of filament yarn






3 thread processing

Thread forming: Combine yarn or silk, or yarn-silk by twisting, the basic process is: tension pre-control → merging → twisting → package

Rope is a special variety in the textile industry, which is made by twisting multiple strands of yarn or threads



2 Progress in yarn processing



1 Development of yarn processing technology






Open end spinning

Separate the fibers into individual fibers and make them agglomerate, and twist them into yarns without mechanical holding at one end

(1) Rotor yarn (or open-end spinning)

The yarn is made by using the negative pressure airflow in the rotor to transport the fiber and the high-speed rotation of the rotor to condense the fiber and twist it.

Suitable for spinning 18～100tex pure cotton yarn, wool yarn, hemp yarn or blended yarn with chemical fiber

(2) Electrostatic yarn

Use high-voltage electrostatic field to polarize fibers and condense them into strands, which are made by twisting a high-speed hollow tube

Suitable for spinning 13-60 tex pure cotton yarn, pure hemp yarn and cotton and linen blended yarn;

(3) Vortex spinning

The spinning method that uses the swirling airflow of the vortex to twist the strands is suitable for spinning 60-100 tex chemical fiber yarn or blended yarn;

(4) Friction spinning (dust cage spinning)

The spinning method that uses the negative pressure airflow in the dust cage to absorb fibers and the dust cage rotates to friction and twist the strands. It is suitable for spinning 10-100 tex pure spinning, blended spinning, and even composite spinning, especially those that are difficult to process by other spinning methods. short fibre;



Self-twist spinning

The reciprocating motion of the twisting roller is used to twist the two strands in the same direction, and the twisting moment of the strands themselves is rewinded together to form a double-stranded yarn with a stable structure. It belongs to non-open-end spinning, and can obtain yarn with thread characteristics, which is used for cotton, wool and chemical fiber fabrics.



Core spun yarn

A yarn with a wrapping structure with filaments as the core and short fibers as the sheath. It is a composite yarn.

Can be realized on ring spinning machine or twisting machine, rotor spinning, vortex spinning, dust cage spinning, self-twisting spinning



Air-jet spinning

A spinning method in which the tangentially blown swirling airflow of the nozzle false-twist the beard from the nip of the front roller, and the protruding fiber ends are wrapped around a non-twisted yarn body to form a yarn.



Bonded spinning

A method in which the fibers in the strands are bonded to each other with an adhesive to form a yarn.



New composite structure yarn

Mainly refers to the composite yarn made by twisting short/short and short/long fibers on the ring spinning machine and the yarn obtained by the single strand splitting or strand gathering method

Sirospun, short/long composite spinning (such as Sirofil), solospun and compact yarn

































2 Development of silk processing



1 Deformation processing

Thermal (mechanical) deformation method: representative of false twist deformation method






Using the thermoplasticity of the synthetic fiber, the synthetic fiber precursor is heated and shaped under strong twist to form a spiral crimp, and after the twist is removed, the spiral crimp is preserved, thereby forming a flexible and fluffy stretch yarn. Such as high-elastic textured yarn and low-elastic textured yarn.



High elastic yarn: It has excellent elastic deformation and recovery ability, and its elongation rate is greater than 100%. It is mostly made of nylon yarn. Mainly used for stretch fabrics;






Low stretch yarn: It has moderate elasticity and bulkiness, generally the elongation is less than 50%, and it is mostly made of polyester yarn. Polyester low-elastic yarns are widely used in knitted fabrics and woven fabrics like wool, silk, and linen; nylon and polypropylene low-elastic yarns are mostly used in decorative fabrics.






Air deformation method:

Air-textured yarn: Overfeed the slightly twisted filament bundle into the high-pressure air jet head. Due to the impact of the jet, the fibers in the tow are disordered to form loops of different sizes, which are twisted back and clamped in the tow to form a yarn .






Network wire: The tow is dispersed into monofilaments under the impact of the vertical airflow, and entangled and entangled at a certain interval to form a relatively fluffy silk.








Combined yarn method

Spinning two kinds of fibers with different shrinkage rates into yarns and putting them in steam, hot air or boiling water. The high shrinkage fibers shrink when exposed to heat, and the low shrinkage fibers are stretched and bent, and the whole yarn becomes fluffy, such as acrylic bulk. yarn



Other methods

The stuffing box method, the knife edge deformation method, the knitting and dismantling method, the gear crimping method, etc., have been seldom used.



2 Denaturation processing

Including surface modification of silk, dipping, plating, coating treatment and splitting, peeling treatment, as well as oxidation and carbonization treatment








Development of 3-wire processing

The development of thread processing is embodied in the changes in appearance and performance, imparting functionality, and moving closer to fabrics and finished products.

Appearance and performance changes: realized through different tensions, changes in yarn thickness, and different feeding methods and tensions;

Functionality: Realized by introducing elastic components, conductive components, moisture-conducting components, lipophilic components and acting as a core thread protective yarn;

Move closer to the fabric and the finished product: through the new processing technology, directly processed into braided thread, composite structure thread, filament/spun yarn combined thread, etc.





3 Structural characteristics of yarn

1 Structural characteristics of commonly used yarns

1 spun yarn

The surface of the yarn is fluffy and the length is different, the luster is dim, and the coverage is good;

The fiber in the yarn has a radial transfer with a large amplitude. The yarn is bulky, feels warm, easy to pilling, and easy to stain;

The fiber strength is not fully utilized, and the extensibility is related to the twist;

Good moisture absorption, less static electricity, comfortable and breathable in contact with the skin;

The processing process of spun yarn is complicated and the process is long.

Ring spun spun yarn

The basic structural feature is that the inner is tight and the outer is loose, there is fiber transfer, the fibers in the yarn are hooked, bent, and protrude from the surface of the yarn; when different fibers are blended, the radial distribution will be uneven; the yarn body has uneven thickness and quality And the structure is also uneven.



Free end yarn

The fiber straightness in the yarn sliver is low, and the number of fibers that are hooked, looped, and folded in half is large; the fiber is less transferred from inside to outside, mostly in the cylindrical spiral line arranged in layers; the evenness of the yarn is good, and it is better than the vortex yarn. Ring-spun yarn; less defects, less hairiness, good abrasion resistance, good dyeing and sizing properties; but the yarn strength is low and the elongation is large.



Self-twisted yarn

The twist of the self-twisted yarn is uneven, and the structure of the yarn is periodically uneven in the longitudinal direction. However, because the two bundles are combined, the evenness of the yarn is better than that of the ring-spun single yarn and worse than the strand; the self-twisted yarn has slightly lower strength and longer elongation. Large, good abrasion resistance, soft and full-feel, and its luster is different from single-twist yarns due to alternating twist directions.



Composite yarn and structural yarn

The structural characteristics of composite yarn depend on the composite ratio of each component and spinning tension;



The structural characteristics of structured yarns depend on the distribution mode and aggregation density of the fibers.




2 Structural characteristics of filament yarn

Ordinary filament yarn:

It has a straight and smooth appearance, no hairiness on the surface, generally has a strong luster, and the fabric has a silky feel;

Poor fluffy, cool and slippery hand, not easy to pilling, not easy to stain, easy to snag, poor coverage;

The fiber strength is fully utilized, the extensibility is small, and the dimensional stability is good;

The hygroscopicity depends on the fiber composition. Thermoplastic fibers have poor moisture absorption, are prone to static electricity, and are impermeable to air.



Untwisted filament yarn

In the untwisted filament yarn, the individual filaments are uniformly stressed and arranged in parallel and straight, but the transverse structure is extremely unstable, easy to pull out and separate, and the yarn body is relatively soft;



Twisted filament yarn

The longitudinal and transverse directions of the twisted filament yarn are very stable, and the twisting effect can adjust the unevenness of the fiber in the entire filament yarn; the yarn body is stiff and round.



Textured yarn

At the same time, it has the characteristics of spun yarn and filament yarn.

Improve the moisture absorption, breathability, softness, elasticity and warmth retention properties of silk;

The surface of the yarn is dull and fluffy, fluffy or elastic, and soft to the touch, thereby improving the covering ability;

The degree of fiber strength utilization is slightly worse than that of filament yarn, and the extensibility is related to the processing method.

The fabric has high dimensional stability and good shape retention;

Maintains the easy-washing and quick-drying characteristics of synthetic fiber fabrics;

Processing is more complicated than filament.

False twist textured yarn: the crimp state is mainly spiral, with spiral loops in both positive and negative directions; the yarn body has a uniform structure, bulky, good warmth and softness, but hooks, fluffing, and pilling; the main features are Fluffy and stretchability, its diameter can be many times higher than the original yarn, depending on the amount of twist, stretchability can also be greatly increased. The elasticity of high elastic yarn can reach 2 to 4 times or more, and the low elastic yarn can be reduced as needed.


Air textured yarn: There are loops of different sizes on the outside, which makes it bulky, feels good, and has characteristics similar to spun yarn;

One of the biggest features of air textured yarn: large bulkiness

The apparent diameter is 50%～100% larger than that of spun yarn;

The specific volume is 2 to 3 times that of the original yarn, so the covering capacity of the yarn is increased, and it is better than that of the low-stretch yarn;

The structure and performance are relatively stable;

The air textured yarn is less aurora and has the luster effect and appearance characteristics similar to natural fibers;

Improve the waxy feeling, and the friction coefficient is close to that of spun yarn.



Bulk yarn: high shrinkage fibers are mostly located in the core layer of the yarn, compactly stacked, and aligned in orientation; while low shrinkage fibers are mostly located in the outer layer of the yarn, loosely arranged and randomly arranged, forming the bulkiness of the yarn.


Structural characteristics of the 3-strand wire

When the number of single yarns twisted at a time is less than 3, the strand structure is stable; 4-5 single yarns are twisted with unstable factors; 6 or more single yarns are twisted, and they will inevitably return to the stable state of 3 twists. ; In order to ensure the structural stability of the strands, double-twisted strands must be used;

The strands and single yarns are arranged in the same twist direction, the twisting is stable, and the strand structure is uniform and stable; the strands and the single yarn are arranged in different twists, the twisting is unstable, and the strand structure is also unstable, which is easy to produce kinks.