Yarns

Presented by

T. Srivani,Asst. Prof., FP

YARN

DEFINITION:

The word yarn or thread is used in common parlance to cover all the linear textile structures. Yarns can be either “single” or “folded”.

“A yarn is an assemblage of fibres or filaments having a substantial length and relatively small cross section, with or without twist, being the end product of a spinning and winding process”

Assemblies of fibres or filaments which are intermediate productsin a spinning process are given special names such as Sliver, roving, bave, top or tow, depending upon the processand the particular intermediate stage.

YARNS

SINGLE YARNS ASSEMBLED YARNS FOLDED YARNS

SPUN YARNS FILAMENT YARNS

FANCY YARNSFANCY YARNS

ROTOR YARNS

RING YARNS

WORSTED YARNS

SEMI-WORSTED YARNS

WOOLLEN YARNS

FLAT FILAMENT YARNS

TEXTURED FILAMENT YARNS

BICOMPONENT TAPE OR SPLIT FILM YARNS

CLASSIFICATION OF YARNS

Yarn may be any of the following

• Number of fibers twisted together

• Number of filaments without twist

• Number of filaments twisted with more/less twist

• Single filament

• One or more strips cut by length of a sheet of material of natural/ synthetic or any polymer

TERMS

SPUN YARNS are made by mechanical assembly and twisting together (spinning) of Staple fibres such as cotton, flax,

wool, spun and noil silk, broken or cut man-made fibres

FILAMENT YARNS are made by the assembly of continuous filaments, made from silk or man-made fibres

A MULTI FILAMENT YARN is a filament yarn made from multiple filaments, assembled with or without twist.

A MONO FILAMENT YARN consists of only a single continuous filament from man-made source.

Two or more yarns which are wound side by side on to same package,

but without twisting around each other, are called ASSEMBLED

YARNS.

FOLDED OR PLIED YARNS are yarns made by twisting togetherTwo or more single (and/or folded) yarns of the same or different types.Ex: 2 Ply (two singles)

CORDS OR CABLED YARNS are yarns made by twisting togetherTwo or more ply or folded yarns of the same or different types.Ex: 2,3 Ply Cord

Twist DirectionTwists or turns per inchTwist Factor (K)

Spun & Filament yarns

Properties of Spun, Filament and Combination Yarns:

100%Spun Yarns: Warmth, Softness, Light Weight Ideal for T-Shirts, Sweaters and Blankets

100%Filament Yarns: Smoother, Finer and Lustrous Ideal for linings

Combination of spun and filament Yarns: Durable, Easy care, Comfortable Suitable for more applications

Twist

• The purpose of twist is to hold the staple fibers together

• The twist could be used in different ways to embed different qualities to the yarn

• A yarn that is twist balanced will not tend to curl

• The direction of twist is also important for further designing as this can be used well by designers

Yarn twist parameters:

Amount of twist is designated as TPI –turns per inch, whichAffects appearance and durability of the yarns.

Spun yarn: Low twist Soft twist yarns flexible(2 to 12 tpi) ex: Knitting fluffier

soft

High Twist Hard twist yarns smooth(20 to 30 tpi) ex: weaving firm

stronger

Filament yarns: Usually low twist Pebbly and harsh surface (1/2 to 1 tpi) Crepe fil. with crepe twist

Twist DirectionTwist can be inserted in eitherof two directions.

S-Twist: Spirals run upward to the left (clock wise)

Z-Twist: Spirals run upward to the right (anti clock wise)

Combination of S and Z twist: to produce crepe fabrics

The majority of the single yarns are twisted in Z direction

S-twist is considered as a reverse twist by the spinner

Direction of twist has no effect on single yarns

Normally the folding twist is in the opposite direction to that of the single yarns.

Balanced twist is when the folding twist is approximately equal and opposite to the singles

Twist factor

The angle of twist is the factor that determines howthe yarn will behave.

Yarns with a low twist level have a lower angle of twist, and will be relatively soft, bulky yarns

Yarns with higher twist angles will be strong, leanand hard yarns

Over twisted yarns will have very high twist angles;They will be very hard, weaker and snarl easily

Typical twist factors:

Short staple end use Tex twist factor

Doubling weft 2900-3200Ring weft 3200-3500Ring warp 3800-4300Voile 4900-5300Crepe 5700-7700Rotor 3700-4700

Twist factor

Tan ө = Пd ll= 1/turns per unit length

d= /¯yarn tex

Therefore, tan ө = turns per unit length X /¯yarn tex

Turns per unit length = K/ /¯tex

Twist factor = turns per inch / /¯cotton count

Twist and Handle• A soft twisted yarn will give a

fuzzy texture.

• A high twisted yarn will increase the surface roughness and increase the grainy texture according to the bulkiness.

• The direction of twist and when they are combined may give interesting effects.

Twist and Bulkiness

• The bulkier the yarn, lesser the twist.• Finer the yarn higher the twist.• Bulkier yarn needs lesser twist and so it has

lesser strength.• Finer yarn has more twists and strong.• But when the twist is increased after

particular point the strength is reduced due to the breakage of the fibers.

Blends / Mixtures

• A blend is a combination of two materials at fiber stage.

• A mix is two materials put together at a later stage as strands.

• The texture we get is different from each of them.

• The design value of these are high.

Need

• The need for blends or mixes are.– Cost.– Different quality that each fiber offers.– More effective usage of the materials.– The necessity of different and in between

qualities and both the qualities.

Design Values

• The design values of such blended and mixed yarn can be explored to give an innovative look to the textile

• More innovative processes can be explored

• The design can happen from yarn stage.

• Fancy yarns are explorations of the prior said attributes such as

• Twist

• Bulkiness

• Color

• Material– Blends and Mixes– Material(conventional/non-conventional)

Fancy Yarns

Varieties

• Boucle• Loop• Gimp• Nep• Chenille • Corkscrew• Core spun• Metallic

Physical properties and performance characteristicsof different yarn types:

Yarn type General yarn properties

Staple yarns Excellent Handle Good covering power

• Carded cotton Good comfort rating• Combed cotton Reasonable strength• Woollen Reasonable uniformity• Worsted• Linen

Yarn type General yarn properties

Continuous filament yarns Excellent uniformity Excellent strength

•Natural Can be very fine•Non-synthetic Fair handle•Synthetic Poor covering power

High bulk yarns Light weight

• Staple Good covering power• Continulous filament Good loftiness and fullness

Stretch yarns High stetchability

Continuous filament Good handle Covering power

Special end use:

•Tyre cord Purely functional•Rubber Designed to satisfy a specific-•Core yarn set of conditions•Cabled•Split film yarn

Novelty yarns: Excellent decorative features

•Fancy yarns•Metallic

Variables in yarn production

Type of fibre or filamentDimensional and physical characteristics of the fibre/filamentMechanical properties of the fibre / filamentGeneral properties Yarn production systemsComponents of the yarn and percentagesLinear density and level of twistYarn constructionTexturisation and method of texturisation