Definition Of Yarn
Yarn can be defined as a linear assembly of fibers or continuous filaments formed into a continuous strand which is having the required characteristics for textile. These textile characteristics referred to include the good tensile strength & high flexibility so that it can be pliable & to be considered to a yarn, these yarns must be processable on conventional textile equipment & must possess the visual & aesthetic characteristics which are usually associated with textile products.
Combination yarns are made by plying the dissimilar components such as staple & continuous filament yarns.
Yarns can be easily classified according to their physical properties & performance characteristics. The classification of yarn is as given below,
- Staple yarn
- Continuous filament yarn
- Novelty yarn
- Special end use yarn
- High bulk yarn
- Stretch Yarn
1 Staple Yarns
There are four different system of manufacturing the staple yarn on the commercial level. These four systems are-
- The carded cotton yarn system
- The combed cotton yarn system
- The worsted yarn system
- The woolen yarn system
In all these four systems of the yarn is made from the staple fibers is nothing but the fibers which are limited in length.
The yarn which is made or formed from the staple fibers is known as staple yarn.
The carded cotton & combed cotton system are used to spin yarn from the short (up to 1 inch) & long (2-3 inch) staple cotton & similar fibers.
The woolen & worsted system are used to spun yarn from the short (up to 2.5”) & long (up to 3.9”) staple fibers & similar fibers.
Manmade fibers are usually cut to a fiber length, diameter & crimp resembling that of cotton & wool for processing on this system.
The fabric made from staple yarn have the good tactile properties such as a good handle, feel & excellent comfort along with the good aesthetic appearance.
2 Continuous Filament Yarn
Before the discovery of the manmade fibers, silk was the only filament yarn.
In the manufacturing manmade filaments, a solution is forced through very fine holes of a spinneret, at which point the solution solidified by coagulation, evaporation or by cooling.
The number of holes in a spinneret determines the number of filaments is the continuous filament yarn.
The size of hole and drawing (if any drawing) then it determines/ affects the diameter of the filament. As soon as the individual filament solidifies, they are brought together with or without slight twist or entanglement to form the continuous filament yarn.
The main advantage of manmade continuous filament yarn is the physical and chemical properties of these yarns are can be altered as per the end use requirement.
The fabric made from continuous filament yarn is much stronger & uniform. Continuous filament yarn is much stronger & uniform than staple spun yarn.
But manmade continuous filaments are lack in their comforts properties, tactile properties, good covering properties & pleasing appearance in their untextured form.
3 Novelty Yarn
Novelty yarn is also called as ‘effect threads’ or ‘effect yarn’ or ‘fancy yarns’.
These yarns are mainly manufactured or designed for decorative purpose rather than functional purpose.
Very rarely the entire fabric is composed of novelty yarn.
Most of the novelty yarns are basically either of fancy effect yarn or metallic type.
The fancy yarn is usually made by the irregular plying of staple or continuous filament yarns & they are characterized by abrupt, periodic effects. The periodicity of this effect is may be random or uniform.
These fancy effects are more often generated by the programmed twist variation or by the change in the rate of feeding rate of one or more components during plying.
Metallic novelty yarns are characterized by a glittering appearance & a rectangular cross-sectional shape
Durability is added to the metallic yarn by protecting with a transparent film like the aluminum foil or metallized material that produces the glittering effect.
Mention acetate & maylar metallic yarns are examples of this categories.
4 Special End Use Of Yarn
The yarns which are specially designed for the special particular end use are called as special end-use yarns
These yarns have the specific functional characteristics with respect to special end use. These yarns are engineered for predictable performance under specific conditions. These yarn most probably does not have the tactile and aesthetic properties. Examples tire cords sewing threads glass yarn coarse spun yarn elastic threads.
5 High Bulk Yarn
This is either staple or continuous filament yarn that has normal extensibility but as usually high degree bulkiness or fullness. These yarns retain their bulkiness under both stressed and relaxed condition.
Great covering power with little weight is possible with this kind of yarns.
Same high bulk yarns are made on staple systems from thermoplastic fibres that shrink differently in treated yarn form. The difference in shrinkage results in massive buckling or crimping of fibre segment between points of entanglement in the yarn structure.
Continuous filament yarn can be made bulkier by the creation of nonlinearity and loop formation in the individual filament by entrapping the loops by the twist.
Very fine, yet bulky structures can be made from the texturized continuous. filament yarns. Combination yarns can also be textured with differential bulk effect.
6 Stretch Yarn
The textured yarn which is programmed for extraordinary extensibility is known as stretch yarn.
Most stretch yarns can be extended from one and one and a half to twice their normal or relaxed length.
Their structures are not only highly extensible but highly elastic is used as well. Here term highly elastic is used to suggest a quick and practically completely recovery towards original yarn geometry or configuration after substantial extension in the direction of yarn axis.
Some stretch yarns are extended up to three or multiple of their relaxed length.
In the relaxed state, stretch yarn resembles high bulk yarns. But where an extension of stretch yarns, however, the bulkiness is considerably reduced. At full extension, the stretch yarn resembles an ordinary continuous filament yarn.
Most of the stretch yarn are made by texturizing thermoplastic continuous filament yarn texturizing brings about considerable non-linearity or crimp in every filament.
However, the tactile properties of stretch yarns are not good as high bulk or staple yarn.
However, there are also some serious disadvantages such as filament engaging.
Stretch yarn should not be confused with rubber or elastomeric fibre yarn, they are normally used in power stretch fabrics where more than a subtle pressure is required.