Tuesday, October 23, 2018

TYPES OF YARN, CLASSIFICATION OF YARN

VARIOUS TYPES OF YARN OR CLASSIFICATION OF YARN:
                                        

YARN:

DEFINITION:  “a continuous strand of twisted textile fibres is called yarn”. The yarn is used in weaving and knitting.

Thread:  

a continuous strand of two or more plies of yarn, in which plies of yarns are twisted together is known as thread”. It is used in needlework and the weaving of cloth.

Difference between yarn and thread:

Every thread is made of yarn. Therefore we can refer thread as yarn. But yarn cannot be referred to the thread.
The main differences between yarn and thread are being given in below table:



CLASSIFICATION OF YARN:

The yarn can be classified in two main categories:
1-  Spun or staple yarn
2-  Filament yarn

Spun yarn:

The yarn made of staple fibres by twisting together is called spun or staple yarn.
It can be classifies in various sub categories according to different bases:
According to the number of plys: 

on the basis of the number of ply, the yarn can be classified into two categories:
a)  Single ply yarn
b)  Multi-plys yarn

a)  Single ply yarn:

The spun or staple yarn having only one ply is called single ply yarn.

b)  Multi-plys yarn:

The spun or staple yarn consisting of more than one ply twisted together or grouped together only is called multi-plys yarn.

According to the direction of the twist: 

on the  basis of the direction of twist the spun yarn can be classified into three categories:
1-   S – twist yarn
2-   Z – twist yarn
3-   Zero twist or twist less yarn

1-  S – twist yarn:

Spun or staple yarn twisted in clock wise direction is called S – twist yarn. Inclination angle of fibres in this yarn makes the shape like S( English alphabet letter).

2-  Z – twist yarn:

Spun or staple yarn twisted in anti-clock wise direction is called Z – twist yarn. Inclination angle of fibres in this yarn makes the shape like Z(English alphabet letter).

3-  Zero-twist or twist less yarn:

This yarn is made by the wrapping of the soluble filament with untwisted staple fibres. Hot water soluble filaments are used for wrapping. After weaving, these filaments are dissolved in hot water during processing. Thus fabric having spun yarn looks like twist less therefore, it is called zero twist yarn.

According to the degree of the twist: 

on the basis of the degree of twist , the spun yarn can be classified in three categories:
1.  Low twist yarn
2.  Normal twist yarn
3.  High twist yarn

1.  Low twist yarn:

This type of yarn contains less degree of the twist than standard. It has bulkiness and soft feel. It posses less strength than normal twist yarn. It shows poor lustre and less clearty in the structure. It looks coarser than normal twist yarn. Pilling properties of fabrics made of this yarn are poor.

2.  Normal twist yarn:

This type of yarn has a normal twist as per spinning norms and specification.

3.  High twist yarn:

This type of yarn contains a higher degree of  twist than standard. This yarn has a rough feel. This yarn  increases the clarity of the texture of the fabric. It posses higher strength than normal twist yarn. It shows good lustre in comparison of normal twist yarn. Yarn looks finer than normal twist yarn. It has better pilling properties.
According to the spinning process used:

according to the spinning technology used, the spun yarn can be classified into two groups:
1.  Ring frame yarn
2.  Open end yarn

1-  Ring frame yarn:

The yarn being spun by the ring frame machine is called ring frame yarn.
It can be further divided in the following categories:
a)  Carded yarn
b)  Super carded yarn
c)  Semi-combed yarn
d)  Combed yarn
e)  Super combed yarn
f)    Compact yarn

a)  Carded yarn:

In this yarn ordinary carding process is done and the yarn is manufactured on the ring frame machine. This yarn has short staple fibres in it. It contains dirt, broken seeds too. It has poor strength and yarn regularities.

b)  Super carded yarn:

This yarn is produced through special carding process and the yarn is manufactured on the ring frame machine. This yarn contains less dirt, broken seeds, and yarn regularities in comparison of carded yarn. It shows better strength and lower hairiness than carded yarn.

c)  Semi-combed yarn:

In this type of yarn, the combing process is done partially. The yarn is manufactured on the ring frame machine. Short fibres, dirt and broken seeds are removed partially from the yarn. Better evenness, hairiness and strength are achieved in this yarn.

d)  Fully combed yarn:

In this type of yarn, perfect combing process is adopted. The yarn is made on ring frame yarn. Most of the short fibres, dirt and broken seeds are eliminated from the yarn. This yarn shows excellent strength, and evenness. It has low hairiness  in it. It shows good lustre and soft feel.

e)  Super combed yarn:

In this type of yarn special combing process is adopted. The yarn is manufactured on the ring frame machine. In this yarn, short fibres and dirt are removed completely. Broken seeds are removed upto optimum level. Fibres are straightened upto maximum level. It has excellent strength, evenness and hairiness level. This yarn contains minimum yarn irregularities.

f)    Compact yarn:

A special compact spinning device in the ring frame is used to manufacture this type of yarn. This yarn show the best strength, evenness,lurte and feel among all spun yarns. It has no short fibres and dirt. It has the best level of hairiness in it. It has the lowest level of irregularities among all spun yarns.

2-  Open end yarn:

This yarn is manufactured on an open-end machine( rottor spinning machine). The yarn is directly spun from sliver obtained from carding. Many processes of spinning are bypassed in this method of producing the yarn. Therefore yarn obtained from this process is cheaper than ring frame yarn.  This type of yarn contains short fibres in it. It has poor strength. It contains more dirt and broken seeds than any ring frame spun yarn having the same mixing of fibres. It shows the poor level of hairiness, lustre and hand feel. This type of yarn contains many irregularities.


·         Low twist yarn
·         High twist yarn
·         Normal twist yarn

Filament  yarn:

 “The yarn consisting of long continuous filaments or fibres either twisted or  only grouped together is called filament yarn”. It may be man-made or synthetic both.
Filament yarns can be classified as follows:


1.  Monofilament yarn
2.  Multi-filament yarn

Monofilament yarn:

“The yarn consisting of only one long continuous filament is called monofilament yarn”. It is generally has the single coarse filament in it. This filament has good strength normally.

Multi-filament yarn:

“The yarn having more than one long continuous filament together is known as multi-filament yarn”. More than one filaments are grouped together. These filaments may be twisted or punched to prevent the fraying of filaments. Some times filaments are grouped together only.

The multifilament yarns further can be classified as follows:
a)  Twisted  filament yarn
b)  Rotto filament yarn
c)  Zero twist filament yarn

a)  Twisted  filament yarn:

The yarn consisting of more than of long continuous  filaments grouped together and having the twist to stop the fraying of filaments is called twisted filament yarn.

b)  Rotto filament yarn:
The yarns consisting of more than one long continuous filaments grouped together and having punches in length at a regular interval of distance to prevent the fraying of filaments is called rotto yarn.

c)  Zero-twist filament yarn:
The yarn consisting of more th
an one long continuous filaments grouped together only is called zero-twist or twist less filament yarn.

Novelty yarn:
 It is typically consists of two or more stands. These yarns are produced to provide decorative surface effects. Based on the purpose, each strand is referred to as the base/core, effect, or binder. The base/core strand provides the structure and strength.

  The effect strand creates decorative detail such as knots and loops. The binder is used to tie the effect yarn to the base yarn if the binding is necessary. 

There is a wide variety of novelty yarns that are produced using different techniques and types of fibres and strands.  The terminology as well as the classification for novelty yarns varies considerably. Some of the commonly used novelty yarn categories are included in this section.

Slub yarn:

The yarn having fixed size  thick places at regular interval of distance is called slub yarn. It may be either single ply or multi-plys yarn.

Flock/flake yarn:

“The yarn having small tufts of different coloured fibres added at intervals is called flock/flake yarn”. These tufts may  be easily pulled out. Flock/flake yarns are generally single yarns.

 Nub, knot, and spot yarn:

 The  plys yarn in which the effect yarn is twisted around the base yarn to produce a thicker area or a bump is called nub, knot or spot yarn. 

Bouclé and loop yarn:

The plys made by  using three sets of yarns – base or core yarn, effect yarn, and tie yarn and having the looped effect around the base or core yarn is called boucle or loop yarn. In this yarn, the effect yarn is tied with core yarn with help of binder yarn.

Spiral and corkscrew yarn:

These  are ply yarns, in which one ply is soft and thick and the other is fine. 

Chenille yarn:

These  are pile yarns that are often made by slitting leno weave fabrics into narrow strips in the warp direction.

Textured yarn:

These  are made of fully drawn filament fibres with a changed surface, shape and texture developed by using the new  spinning techniques. Nylon and polyester are two main fibres that are textured. Textured yarns provide many variations in fabric properties. There are two main types of textured yarns:

1.  Stretch yarns  
2.  Bulk yarns

Stretch yarn:

  It is manufactured by using one of the following methods.
1.   By using special heat setting treatment to thermoplastic filament fibres such as nylon and polyester
2.   From elastomeric fibres.
3.   From bi-component fibres
4.    From bi-constituent fibres.
5.   From chemically treated natural fibres.  

Bulk Yarns:

These  are softer and much pliable then tightly constructed twisted yarns. Bulk yarns are also have a better cover. They create a less transparent fabrics and are of two types:
1. High bulk yarns
2. Loop-bulk or airjet yarns

Hollow yarn ( air rich yarn) : 

This yarn is made of staple fibers. Some quantity of PVA fibers is added with the main content. this PVA content is soluble in hot water and is eliminated completely after processing. Thus the hollow space ( air space) is created in the yarn. this yarn becomes softer. the moisture absorbency of yarn is also increased.
                               
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