YARN AND YARN MANUFACTURING-Classification of Yarn-4.2.1

Classification of Yarn

Classification of yam according to their structure : 

Yarns may be divided into three types according to their structure as follows: 

1. Staple fibre yams or Spun yams (Single yarn):  Spun yarns are made by mechanical assembly and twisting together (spinning) of staple fibres. Ring spinning, Rotor spinning, Wrap spinning, Air-jet spinning etc. machines are used to produce this spun or single yarns. 
   
2. Ply yarn:   Single yarns are used in the majority of fabrics for normal textile and clothing
   applications, but in order to obtain special yarn features, particularly high strength and
   modulus for technical and industrial applications, ply yarns are often needed. A folded
   or ply yarn is produced by twisting two or more single yarns together in one operation,
   and a cabled yarn is formed by twisting together two or more folded yarns or a
   combination of folded and single yarns. The twisting together of several single yarns
   increases the tenacity of the yarn by improving the binding-in of the fibres on the outer
   layers of the component single yarns. Ply yarns are also more regular, smoother and
   more hard wearing. The direction of twisting is designated as S or Z, just as in single
   yarns. Normally the folding twist is in the opposite direction to that of the single yarns. 
   
             
3. Filament yams:   A filament yarn is made from one or more continuous strands called filaments where each component filament runs the whole length of the yarn. Those yarns composed of one filament are called monofilament yarns, and those containing more filaments are known as multifilament yarns. For apparel applications, a multifilament yarn may
   contain as few as two or three filaments or as many as 50 filaments. In carpeting, for
   example, a filament yarn could consist of hundreds of filaments. Most manufactured
   fibres have been produced in the form of a filament yarn. Silk is the only major natural
   filament yarn.
   
     

According to the shape of the filaments in the yarn, filament yarns are classified into
two types, flat and bulk. The filaments in a flat yarn lie straight and neat, and are
parallel to the yarn axis. Thus, flat filament yarns are usually closely packed and have a
smooth surface. The bulked yarns, in which the filaments are either crimped or
entangled with each other, have a greater volume than the flat yarns of the same linear
density. Texturing is the main method used to produce the bulked filament yarns. A textured yarn
is made by introducing durable crimps, coils, and loops along the length of the
filaments. As textured yarns have an increased volume, the air and vapour permeability
of fabrics made from them is greater than that from flat yarns. However, for
applications where low air permeability is required, such as the fabrics for air bags, flat
yarns may be a better choice. Textured yarns are used for Stockings and tights,
swimwear, sportswear, outerwear, underwear, carpets, sewing and overedge stitching
threads for extensible fabrics.  

Classification of Yams according to their use: 

Yarns may be divided into two classifications according to their use :

Weaving yarns and knitting yarns. 

 
Weaving Yams : Yarns for woven cloth are prepared for the intended end use. Yarns to be used in the
warp, the lengthwise direction of a cloth, are generally stronger, have a tighter twist,
and are smoother and more even than are yarns used for filling, the crosswise direction
of a cloth. Novelty yarns may be used in the warp, but they are generally found in the
filling. Highly twisted crepe yarns are usually found used as filling yarns.

Knitting Yarns:  These may be divided into yarns for hand knitting and yarns for machine knitting.

Knitting yarns are more slackly twisted than yarns for weaving. Hand knitting yarns are
generally ply, whereas those for machine knitting can be either single or ply. The
following are some of the yarns used for hand knitting: 

1. Knitted worsted: The four-ply all-around yarn used for accessories, for the house,
   and for apparel. This is the most common weight of hand-knitting yarn,
   comprising 90 percent of the handmade yarn business
2. Fingering (baby or sock) yarn: The fine yarn that was originally wool, but is found
   most commonly in acrylic for comfort and ease of care.
3. Sport yarn: The three-ply yarn used for socks, sweaters, and hats
4. Shetland yarn: The two-ply yarn used for sweaters.
5. Fashion or novelty yarn: Any novelty structure.

All the yarns listed may be found in any fibre. Of the major fibres, rayon is the least likely to be
used in the handmade yarn business.