1. Student Name: MD Ashraful Islam
Shafiqul Islam Shanto
Shahin Alam
Johorul Islam
Fazly Rabbi
Department: Textiles
Presentation submitted to:
Nur Nahar Akter
Senior lecturer
Department of textile engineering

2. Welcome To My Presentation !

3. Presentation topic:
Introduction and application of Yarn Geometry

4. What is Textiles ?
Textile is a very widely used term which includes:
 All kinds of fiber
(Cotton, Jute, Wool, Polyester, Viscose )
 All kinds of Process
(Spinning, Weaving, Knitting, Dyeing, Printing, Finishing)
 All kinds of machineries
(Spinning machineries, Weaving machineries,
Knitting machineries, Dyeing machineries)
 To convert textile into finished or end use products (Garments,,
Technical textiles, Geo textiles, Medical textiles)

5. What is yarn?
According to textile institute, yarn may be defined as a
product of substantial length & relatively small cross
section consisting of fibers or filament with or without
twist. It has some characteristics:-
-Tensile strength
-High flexibility
-Extensibility

6. Classification of yarn according to structure:
 Continuous filament yarn
 Staple yarn
 Core spun yarn
 Novelty yarn
 Stretch yarn
 High bulk yarn

7. Continuous filament yarn
 Continuous filament yarns are the simplest in the
structure.
 Manufactured By a solution in forced through very fine
holes of spinneret at which point.
The solution solidified by according-
coagulation (in wet processing)
evaporation (in dry process)
and cooling (in melt processes)

8. Continuous filament yarn

9. Properties of Continuous filament yarn:
It has excellent Strength
Excellent Uniformity
Less tactile qualities
Low comfort and a pleasing appearance

10. Staple yarn:
 Yarn in which a number of discontinuous fibers are
held together generally by twisting is called staple yarn

11. Properties of staple yarn:
Staple yarn has good tactile qualities
Good covering power
Excellent comfort factors
Good handle properties
But are not strong & uniform

12. Core spun yarn/ complex yarn
Core spun yarn are two component structure with core &
sheth. Generally continuous filament yarn is used as core and
staple fibers are used as sheth covering.
This types of yarn has two properties:
 Functional properties
 Aesthetic properties

13. Core spun yarn

14. Novelty yarn:
 Novelty yarn are design for decorative rather than
functional properties.They are usually uneven in size,
varied in color or modified appearance by the presence
of irregularities during their formation.

15. Novelty yarn

16. Stretch yarn:
Yarn that have been programmed for extra-ordinary
extensibility are known as stretch yarn. They can be
extended from one & one half to twist in their normal
length

17. Stretch yarn

18. High bulk yarn:
 High bulk yarn is a staple or continuous filament yarn.
It has normal extensibility .Great covering power with
little wt. is possible.
High bulk yarn

19. What is yarn Designation?
 The factor which are required to express yarn structure and
properties wholly, are called yarn designation.
 The factors of yarn designation are:-
 Yarn Count / Linear Density.
 No. of Filaments.
 Fibre components.
 No. of components in folding.
 Direction & amount of twist.

20. Properties of Ideal Yarns
 The yarn in circular in cross-section and is uniform along its length.
 Yarn is composed of concentric layers of different radial.
 Each fibre follows a uniform helical path around one of the concentric
cylinder so that its distance from yarn axis remains constant.
 A fibre at the center will follow a straight line of the axis.
 The axis of circular cylinders coir sides with yarn axis.
 Every filament in the yarn will have the same amount of twist per unit
length.
 The yarn consists of very large number of filaments.

21. packing of fiber in yarn
Fiber arrangement in yarn cross section is called packing
of fiber in yarn.
It cab be described by two basic forms:-
 Open packing
 Close packing/Hexagonal packing

22. Open packing
 Open packing is that in which the fibers lie in layers
between successive concentric circles. At the center of
circular fibers, There is a single fiber around this six
fibers can be packed to that all seven fibers are
touching. Then third layer and successive layer create
by some manner.

24. Close packing/Hexagonal packing
 Close packing is that in which the fibers fit into a
hexagonal pattern. Here with a single fiber core, close
packing of circular fibers given a yarn with a hexagonal
outline in which all are touching each other.

25. Close packing

26. Packing density
 Packing density may be defined as the ratio of specific
volume of fibers in yarn to the specific volume of yarn
after packing.
 Maximum density value for filament yarn 1
 Packing density value for staple yarn 0.60 to 0.65

27. Optimum twist factor
The twist factor at which maximum strength is
achieved in any given staple yarn is called optimum
twist factor.The optimum twist factor of a yarn
depends on following factors:-
 Fiber length
 Fiber fineness
 Frictional properties of fiber
 Count of yarn

28. Twist contraction
Twist contraction may be defined as the change in
length of yarn during twisting. when yarns are twisted,
they contract because of the longer path followed by the
fibers.
The contraction defined in two ways
Contraction factor
Retraction factor

29. Contraction factor
 The factor by which the draft must be increased in order to
prevent the decrease in yarn count or size due to twist
contraction. contraction factor represents by Cy .

30. Retraction factor
 Retraction factor represents the fractional decrease in
length or increase in linear density of filament yarn during
twisting.
 Retraction factor represents by Ry

31. Basic geometry of twisted yarn
 R- Yarn radius
 r-radius of cylinder containing helical path of particular fiber (cm)
 T- Yarn twist, turns per unit length (cm)
 h- length of yarn having one turns of twist (cm)
 α- surface angle of twist at radius R
 θ- corresponding helical angle at radius r
 l –length of fiber in one turn of twist at radius r
 L- length of fiber in one turn of twist at radius R
Idealized yarn geometry

34. Basic geometry of twisted yarn
 R- Yarn radius
 r-radius of cylinder containing helical path of particular fiber (cm)
 T- Yarn twist, turns per unit length (cm)
 h- length of yarn having one turns of twist (cm)
 α- surface angle of twist at radius R
 θ- corresponding helical angle at radius r
 l –length of fiber in one turn of twist at radius r
 L- length of fiber in one turn of twist at radius R