Basics of fibres and yarns

1. Introduction to Fibres and yarns
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2. A brief history of fibres and yarns
• Although it has yet to be discovered precisely
when man first began spinning fibers into yarns,
there is much archaeological evidence to show
that the skill was well practiced at least 8000
years ago.
• Certainly, the weaving of spun yarns was
developed around 6000 B.C., when Neolithic man
began to settle in permanent dwellings and to
farm and domesticate animals.
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3. A brief history of fibres and yarns
• The history of textile fibre is as old as civilization,
as we get reference of the usage of natural fibres
thousand of years ago.
• During ancient times, the natural fibres like
cotton, silk, wool and flax were used.
• Later due to improvement in science and
technology, synthetic fibres like Nylon, Polyester
have been developed, which leads to engineer
fibres as per requirements of the end use.
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4. Textile Fibre-Definition
• A textile fiber is a unit of matter, either natural
or manufactured, that forms the basic
element of fabrics and other textile structures.
• A fibre is usually having a substantial length
compared to its cross section (diameter). This
ratio could vary from 100 times to 1000 times
even.
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6. Textile fibres classification
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7. Textile yarn-Definition
• A textile yarn is an assembly of substantial
length and relatively small cross section of
fibres and/or filaments with or without twist.
• Textile fibres are converted in to yarns by
twisting operations used to bind them
together.
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8. 1/31/2023 8
Textile Yarns

9. Textile yarns classification
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Textile Yarns
Staple spun yarns Continuous filament yarns
1) By fibre length 1) By filament number
Short staple yarn<60mm (eg:Cotton) Mono filament yarn
Long staple yarn>60mm (eg: Wool) Multifilament yarn
2)By spinning system 2) By fibre treatment
Ring spun yarn Flat continuous yarn
Rotor spun yarn (O/E) Textured yarns
Core spun yarn
Air jet spun yarn 3) Other specialty yarns
Friction spun yarn (DREF) Bi-component yarn
Wrap spun yarn Tape or split films yarn
Self twist yarn Elastomeric yarn
Metallic yarn
3) By yarn construction
Single 4) Covered elastomeric yarns
Plied single covered
Corded double covered
Cabled air covered
Fancy yarns(complex, novelty)

10. Fibre properties
• To be designated as a textile fibre any material
should satisfy two important characteristics,
namely, the essential or the primary
properties and the desirable or the secondary
properties.
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11. Essential/primary properties of a fibre
• 1. Fibre Length
• 2. Strength and related properties
• 3. Flexibility
• 4. Cohesiveness
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12. Desirable/secondary properties of a
fibre
• 1. Fineness
• 2. Resiliency
• 3. Uniformity
• 4. Porosity
• 5. Lustre
• 6. Durability
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13. Primary properties of fibres
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14. 1.Fibre Length
• Length is an important parameter which determines the
usefulness of a textile fibre from the point of view of
spinning.
• The length of the fibre should not be less than 5 mm. It is of
course very easy to understand that when a continuous
yarn is to be made out of individual fibres, it should possess
a considerable length with reference to its diameter,
otherwise it would not be possible to make a yarn that
would hold together the constituent fibres.
• This is referred to as the length to breadth ratio. The most
useful fibres should have length to breadth ratios of more
than 100:1. Almost all textile fibres have length to breadth
ratio of more than 1000:1.
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15. Length:diameter ratio of fibres
Typical ratios for several natural fibres are as
follows:
• Cotton = 1400,
• Wool = 3000,
• Flax = 1209,
• Ramie = 3000,
• Silk = 33 × 10^6
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16. 2. Fibre strength
• Strength of any material is derived from the load it
supports at break and is thus a measure of its limiting load
bearing capacity.
• Normally strength of a textile fibre is measured in tension
when the fibre is loaded along its long axis and is
designated as Tensile strength.
• Tensile strength of textile fibre is measured as the
maximum tensile stress in force per unit cross-sectional
area or per unit linear density, at the time of rupture called
‘tenacity’, expressed in terms of grams per denier or grams
per tex units.
• In Standard International Unit (SI Unit) tenacity is expressed
as millinewtons per tex.
• Tenacity = maximum tensile strength at break
Surface area
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17. 3. Fibre flexibility
• The fibre should be sufficiently pliable; then
only it can wrap around another fibre during
spinning.
• If, on the other hand, fibre is stiffer and wirier,
then it is less adaptable for textile use, for
example, glass and metallic fibres.
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18. 4. Fibre cohesiveness
• It is the property of an individual fibre by virtue of which the fibres
hold on to one another when the fibres are spun into yarn.
• This action is usually brought about by the high degree of frictional
resistance offered by the surface of the fibres to separate one from
the other.
• The wool fibres, for example, have saw-toothed surface, so that the
projecting edges on its surface, called scales, easily catch on to one
another when several such fibres are twisted together during
spinning.
• On account of this, fibres offer resistance when an attempt is made
to pull them apart.
• Cotton fibres also possess irregular or rough surface. Further, due to
the natural twist in the cotton fibre known as convolution, the
fibres interlock themselves by friction when they are spun into
yarns. The introduction of crimp in synthetic fibre increases
cohesion.
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19. Secondary properties of fibres
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20. 1.Fibre fineness
• Fineness of a fibre is a relative measure of its size,
diameter, linear density or weight per unit length
expressed in a variety of units.
• Natural fibres vary in fineness more widely than
manmade fibres, because in case of manmade
fibres the diameter and densities can be
controlled very accurately during their
manufacture.
• For example, the variation in the diameter of
nylon is only 5–6%, while for natural fibres like
wool and silk, it is from 17 to 30%.
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21. 2.Fibre resilience
• The resistance to compression, flexing or torsion varies
from fibre to fibre.
• Some fibres have a natural tendency to return to their
original condition when any of the above mentioned
forces is applied, an important property where, for
instance, recovery from creasing is required.
• Wool is outstanding in this respect by virtue of its
natural characteristics, but cellulosic fibres may be
modified in such a manner so as to greatly improve
these properties.
• It is believed that the resilience of a fibre is more a
function of molecular cohesion.
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22. 3.Fibre uniformity
• Textile fibres should possess uniformity in their
thickness and length.
• Unfortunately none of the principal natural fibres
like cotton or wool has the same length and
diameter of the fibre in the same lot.
• Fibres in any specified qualities, grades or lots
vary considerably in length and diameter.
• On the other hand, manmade staple fibres are
more uniform as they are cut to the exact length
after being spun and drawn, and even the
diameter can be controlled within close tolerance
limits during its manufacture.
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23. 4.Fibre porosity
• Porosity can be defined as the ratio of the volume of air
contained within the boundaries of the material to the total
volume of a solid plus air or void, expressed as percentage.
• Porosity facilitates the absorption of moisture, liquid
lubricants, dyes, oils and steam by the fibres so as to
thoroughly permeate the fibre.
• Porosity in a fibre is important in wet processing. The
natural and manmade fibres differ greatly in respect of
porosity which in turn affects other properties of fibres and
consequently the processing of fibres during textile
manufacture.
• In general, natural fibres have higher porosity than
synthetic fibres.
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24. 5.Fibre lustre
• Natural lustre enhances the value of textile fibre especially
of natural fibres.
• For example, the natural lustre of the silk gave it for a long
time distinct advantage over the other textile fibres, and
experiments were constantly made to improve the lustre of
those fibres which were naturally dull.
• Mercerized cotton, for instance, is a preferred cotton which
has not undergone this treatment, owing to the richer
appearance of the finished cloth.
• Since the introduction of viscose, however, with its
extremely high and almost metallic lustre, consumer taste
has gone a little in the opposite direction, and many fabrics
produced today are purposely delustred in order to give the
desired matt finish.
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25. 6.Fibre durability
• A textile fibre should withstand processing treatments and
should not be easily susceptible to physical, chemical and
bacteriological attack, which may result in damage and
decomposition.
• The durability of clothing to average wear and tear depends
somewhat more on the elasticity, flexibility and resistance
of the fibre and fabric, rather than the absolute strength of
either fibre or fabric.
• If a fabric possesses these three properties, its garment will
absorb or counter more readily stresses and strains during
wear.
• It will allow itself to be deformed with less resistance, thus
reducing the chance of intermediate tearing or twisting.
• For these reasons wool garments owe much of their
durability to the elasticity, resilience and flexibility of the
fibre and fabric, even though wool is a weak fibre.
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