Showing posts with label Cotton. Show all posts
Showing posts with label Cotton. Show all posts
6 October 2012
Physical Properties of Cotton Fibres
Cotton Fiber:
Properties of cotton fiber can be divided into two parts, one is according to physical structure and another is using process.
A. According to physical structure:
Length of cotton fiber:
Physically the individual cotton fibres consist of a single long tubular cell. Its length is about 1200-1500 times than its breadth. Length of cotton fibre varies from 16mm to 52 mm depending upon the type of cotton.
Longer the fibre, finer the fibre in case of cotton fibre. It is expressed in term of decitex and it varies from 1.1 to2.3 decitex.
Strength and extension of cotton fiber:
Cotton fibre is fairly among natural fibres in relation to tenacity which is 3-3.5g/dtex. Its tensile strength is between wool and silk fibre but disadvantage is low extension at break which is 5-7%.
Elastic properties of cotton:
Recovery from deformation of cotton fibre, yarn or fabric from applied load is very low. By applying heat it can’t be achieved. This property can be achieved by -1.Chemical treatment to improve crease recovery, but the problem is the materials become harsher due to chemical treatment 2. blending or mixing of cotton with elastic fibre, e.g. polyester, blend ratio depends on the end use of the fabric. The initial modulus is fairly high=0
5 g/dtex (wool=0.25 g/dtex)
Cross-section:
Cross-section of cotton fibre is some what ribbon like. The cell wall is rather thin and the lumen occupies about two-third of the entire breadth and shows up very prominent in polarized light. Fibre cross-section becomes round when mercerized.
Appearance:
Cotton fibre is fairly short, fine and creamy white color. Color of the fibre depends on soil of growth. By adding chemicals in the soil, color of the cotton fibre may be varied.
Crimp:
Cotton fibre is more or less twisted on its longitudinal axis which cab not be seen from out side is called convolution. The twist in the fibre does not to be continuous in one direction i.e. if at first right direction, then left direction. This property of cotton fibre helps in spinning.
B. According to using process:
Comfortable:
Soft Hand:
Absorbent:
Good Color Retention:
Machine Washable & Dry Cleanable:
Good Strength:
Cotton Fibre Drapes Well:
Sewing & Handling Is Easy:
Among
the seed and fruit fibres, cotton has grown in stature as the most
important textile fibre in the world. In fact, cotton is the backbone
and basic foundation of the world’s textile trade and industry. Cotton
is a natural vegetable fibre produced in the cotton plant in many
countries of the world even in Bangladesh also.
Properties of Cotton Fibres:
Properties of Cotton Fibres:
Properties of cotton fiber can be divided into two parts, one is according to physical structure and another is using process.
A. According to physical structure:
Length of cotton fiber:
Physically the individual cotton fibres consist of a single long tubular cell. Its length is about 1200-1500 times than its breadth. Length of cotton fibre varies from 16mm to 52 mm depending upon the type of cotton.
- Indian cotton- 16-25 mm
- American cotton- 20-30 mm
- Sea Island- 38-52 mm
- Egyptian cotton- 30-38 mm
Longer the fibre, finer the fibre in case of cotton fibre. It is expressed in term of decitex and it varies from 1.1 to2.3 decitex.
- Indian= 2.2-2.3dtex
- American= 2.1-2.2 dtex
- Egyptian= 1.2-1.8 dtex
- Sea Island= 1.0-1.1 dtex
Strength and extension of cotton fiber:
Cotton fibre is fairly among natural fibres in relation to tenacity which is 3-3.5g/dtex. Its tensile strength is between wool and silk fibre but disadvantage is low extension at break which is 5-7%.
Elastic properties of cotton:
Recovery from deformation of cotton fibre, yarn or fabric from applied load is very low. By applying heat it can’t be achieved. This property can be achieved by -1.Chemical treatment to improve crease recovery, but the problem is the materials become harsher due to chemical treatment 2. blending or mixing of cotton with elastic fibre, e.g. polyester, blend ratio depends on the end use of the fabric. The initial modulus is fairly high=0
5 g/dtex (wool=0.25 g/dtex)
Cross-section:
Cross-section of cotton fibre is some what ribbon like. The cell wall is rather thin and the lumen occupies about two-third of the entire breadth and shows up very prominent in polarized light. Fibre cross-section becomes round when mercerized.
Appearance:
Cotton fibre is fairly short, fine and creamy white color. Color of the fibre depends on soil of growth. By adding chemicals in the soil, color of the cotton fibre may be varied.
Crimp:
Cotton fibre is more or less twisted on its longitudinal axis which cab not be seen from out side is called convolution. The twist in the fibre does not to be continuous in one direction i.e. if at first right direction, then left direction. This property of cotton fibre helps in spinning.
B. According to using process:
Comfortable:
Cotton
fiber has large amorphous portion and this is why the air can be in and
out through cotton fiber. So, the fabric made by cotton fiber is quite
comfortable to use.
Soft Hand:
Cotton
fiber is too much regular fiber and if properly ginned; this fibre can
be the best soft hand feeling fibre amongst the others.
Absorbent:
Cotton fiber has high absorbency power and this is why this fiber can be died properly and without any harassment.
Good Color Retention:
If
the printing is applied on cotton fiber, it seems it doesn’t spread the
color outside the design. So printing efficiency is good on cotton
fibre.
Machine Washable & Dry Cleanable:
It
is seen that some fibers can’t be dried or washed due to it’s
sensitivity and weak fastness properties but in case of Cotton fiber you
will have large number of options to choose. You can easily wash the
cotton made fabric by machines and even you will be able to dry this
fiber by using electronic drier.
Good Strength:
If
you want to seek an average strength which might be enough for you;
then cotton fiber can be your ultimate choice. The strength of cotton
fiber is quite good.
Cotton Fibre Drapes Well:
The
drape-ability of cotton fibre is awesome. You can use the cotton fibre
made fabric in any kind of wear which needs more flexibility and
drapes.
Sewing & Handling Is Easy:
The
sewing efficiency on Cotton made fabric is easier and comfortable than
other fiber. This is why the demand of cotton made fabric is higher in
all over the world.
Uses of Cotton Fiber:
Cotton fiber is a versatile fibre which has wide variety of uses. But the Cotton fibre is mostly used on the Apparel Industry to make the wearing cloth like Sweaters, Skirts, Shirts, Swimwear, Kids wear, Blouses, Pants, Hosiery and to make other type of dresses.
http://textilelearner.blogspot.com/
Uses of Cotton Fiber:
Cotton fiber is a versatile fibre which has wide variety of uses. But the Cotton fibre is mostly used on the Apparel Industry to make the wearing cloth like Sweaters, Skirts, Shirts, Swimwear, Kids wear, Blouses, Pants, Hosiery and to make other type of dresses.
http://textilelearner.blogspot.com/
9 May 2012
Production of Cotton Fiber From Field to Mill
Cotton:
Cotton,
the purest form of cellulose found in the nature is the seed hair of
the plants of the genus Gossypium. It is classified as natural,
cellulosic, mono-cellular, staple fiber.
Cotton has been cultivated for more than 5000 years. Archeologists
found that it was grown and used for textile purposes in the Indus
Valley well before 2100 BC, and in Mexico by 3500 BC Cotton has been of
service to mankind for so long that its versatility is almost unlimited
and new uses are constantly being discovered.
 |
| Cotton fiber |
Cultivation:
Cotton requires about two hundred days of continuous warm weather with
adequate moisture and sunlight; frost is harmful to the plant. Usually
in March or April selected cottonseeds are planted. The flowers in
cotton plants appear in June or July and the cotton is usually ripe for
gathering between August and October. The seasons may differ in the
different places of the world. As the flower withers it is succeeded by a
closed pod. This contains seeds, which are wrapped up in young actively
growing hairs. Each cottonseed may produce as many as 20,000 fibres.
When the seeds are nearly ripe the pod burst open and the cotton hairs
project, forming a white fluffy mass called a boll. During this period,
the plant is subject to attack by many insects (e.g. Boll weevil, Boll
worm, Caterpillar). Insecticides are sprayed to protect the plants at
this stage. The fibers are now exposed to the sun when they complete
their ripening, and the cell gradually dries up, leaving the cotton in
fit state for harvesting.
Harvesting: The ripe bolls having matured fibers are picked by machines in developed countries and by hand in developing countries. Mechanical picking, a faster and cost-effective method of harvesting, has some disadvantages as machine picks the immature bolls, as well as leaves, stem fragments with the matured bolls. On the other hand higher grade of cotton is obtained by a selective and good hand picking. An expert picker can easily trace out the matured bolls and does not pick leaves or stem fragments with it. This method is slower and the most expensive in developed countries but better for developing countries.
Ginning: After the crop has been gathered the fibers are separated from the seeds by a process known as ginning. Gins (i.e. ginning machines) may be classified into two types the saw gin and the roller gin. A saw gin consists of a series of circular saws having specially shaped teeth and used mainly for short and medium staple cottons.
Modern gins have 80-120 saws mounted on a long, horizontal shaft at suitable intervals. Seed cotton is fed through a hopper and the saws operate against it as the fibres known as lints become separated from the seed. In a roller gin, a knife jerks the seed from the fibre while the latter is pulled away between a roller and a fixed knife. McCarthy gin is a special type of roller gin. Roller ginning which is often preferred for longer fibres is slower and more costly process.
Cotton linters are the short, fuzzy hair-like fibres that remain on the seeds after ginning has been done. The cotton linters are removed by a second ginning process. They are used in the manufacture of viscose (or rayons) and acetates, plastics, shatter proof glass, photographic film and for other purposes.
Baling: After ginning, the lints are compressed into rectangular bales, which are covered with jute or polypropylene bagging and bound with iron bands. The bales generally weigh about 480 or 500 pounds each. These bales are then sent to the yarn manufacturing mills
Grading: The assessment of cotton is carried out traditionally by the cotton classer, who depends upon personal skill and long experience in judging cotton quality by inspection and feel. The assessment is based on (1) the staple length, (2) the colour and (3) the amount of impurity in the cotton. The classer works usually by a hand-examination of the cotton. Staple length is judged by taking a sample and pulling it to display a filmy web of fibre.
http://textilelearner.blogspot.com/
Harvesting: The ripe bolls having matured fibers are picked by machines in developed countries and by hand in developing countries. Mechanical picking, a faster and cost-effective method of harvesting, has some disadvantages as machine picks the immature bolls, as well as leaves, stem fragments with the matured bolls. On the other hand higher grade of cotton is obtained by a selective and good hand picking. An expert picker can easily trace out the matured bolls and does not pick leaves or stem fragments with it. This method is slower and the most expensive in developed countries but better for developing countries.
Ginning: After the crop has been gathered the fibers are separated from the seeds by a process known as ginning. Gins (i.e. ginning machines) may be classified into two types the saw gin and the roller gin. A saw gin consists of a series of circular saws having specially shaped teeth and used mainly for short and medium staple cottons.
Modern gins have 80-120 saws mounted on a long, horizontal shaft at suitable intervals. Seed cotton is fed through a hopper and the saws operate against it as the fibres known as lints become separated from the seed. In a roller gin, a knife jerks the seed from the fibre while the latter is pulled away between a roller and a fixed knife. McCarthy gin is a special type of roller gin. Roller ginning which is often preferred for longer fibres is slower and more costly process.
Cotton linters are the short, fuzzy hair-like fibres that remain on the seeds after ginning has been done. The cotton linters are removed by a second ginning process. They are used in the manufacture of viscose (or rayons) and acetates, plastics, shatter proof glass, photographic film and for other purposes.
Baling: After ginning, the lints are compressed into rectangular bales, which are covered with jute or polypropylene bagging and bound with iron bands. The bales generally weigh about 480 or 500 pounds each. These bales are then sent to the yarn manufacturing mills
Grading: The assessment of cotton is carried out traditionally by the cotton classer, who depends upon personal skill and long experience in judging cotton quality by inspection and feel. The assessment is based on (1) the staple length, (2) the colour and (3) the amount of impurity in the cotton. The classer works usually by a hand-examination of the cotton. Staple length is judged by taking a sample and pulling it to display a filmy web of fibre.
http://textilelearner.blogspot.com/
16 February 2012
Bale Management
Bale Management:
Testing, sorting and mixing bales according to the properties of fibre for producing specific good quality of yarn at minimum cost is called Bale management.
Object of Bale Management:
1. An evening out of the quality characteristics of a yarn.
2. A means of avoiding quality jumps.
3. A possibility of reducing costs as a result of an improved knowledge of the fibre characteristics.
Specification of a Cotton Bale:
1. Origin: CIS( UZ bekistan) raw cotton
2. Crop year: 2008-2009
3. Bale weight: 215-220 kgs(approximately).
4. Staple length: 1 inches
5. Micronaire: 4.0 – 4.8
6. Strength : 24-29 gram/tex
7. Grade: SMW( Strict middling white)
8. Price: 65.5 usc/lb
Managing Bales:
To manage the bales we need four modules of fibers and the relation exist between fibers and yarn. They are:
Object of Bale Management:
1. An evening out of the quality characteristics of a yarn.
2. A means of avoiding quality jumps.
3. A possibility of reducing costs as a result of an improved knowledge of the fibre characteristics.
Specification of a Cotton Bale:
1. Origin: CIS( UZ bekistan) raw cotton
2. Crop year: 2008-2009
3. Bale weight: 215-220 kgs(approximately).
4. Staple length: 1 inches
5. Micronaire: 4.0 – 4.8
6. Strength : 24-29 gram/tex
7. Grade: SMW( Strict middling white)
8. Price: 65.5 usc/lb
Managing Bales:
To manage the bales we need four modules of fibers and the relation exist between fibers and yarn. They are:
- Strength
- Length
- Color grade and
- Micronaire value
15 December 2011
Cotton Carding Process | Working Process of Cotton Carding
Carding
Carding is one of the most important operations in the spinning process
as it directly determines the final features of the yarn, above all as
far as the content of neps and husks are concerned. There are many
objectives of the carding process and these can be summarised as:
- Opening the tufts into individual fibres;
- Eliminating all the impurities contained in the fibre that were not eliminated in the previous cleaning operations;
- Selecting the fibres on the basis of length, removing the shortest ones;
- Removal of neps;
- Parallelising and stretching of the fibre;
- Transformation of the lap into a sliver, therefore into a regular mass of untwisted fibre.
Fig.A Section view of the card with hopper
Wiring and Clothing
There are different types of cylinder wiring, in particular:
- rigid wiring, for rotating parts;
- elastic clothing, for mobile flats;
- clothing for fixed flats.
The
most common on the machine are the wiring type. They are made up of a
steel wire with sharp cutting teeth, the sawtooth like edge of the
wiring is hardened in order to better resist wear caused by the abrasive
action of the fibres. The base of the wiring is thicker than the
toothed parts, both to guarantee support to keep the teeth in a vertical
position, as well as to prevent lateral contact between the teeth and
to permit the necessary momentary penetration of fibre into the wiring.
The sizes of the teeth vary notably and depend on how compact the material is, on the quantity and on the fineness of the fibre. The parameters which permit one type of wiring to be distinguished from another are:
The sizes of the teeth vary notably and depend on how compact the material is, on the quantity and on the fineness of the fibre. The parameters which permit one type of wiring to be distinguished from another are:
Concentration,
meaning the number of teeth in a square inch of the wiring (for the
various devices of the card the concentration is different and is
strictly linked to the type of fibre used; for fine fibre, for example,
wiring with a high concentration is used);
- The height of the teeth, which can vary according to the wired element;
- The angle between the teeth and the base in a longitudinal sense.
It is a known fact that a wired element moves in:
- a positive way when it moves in the same direction as the inclination of the teeth;
- a negative way when it moves in the opposite direction to the inclination of the teeth
The
fibrous material is found between the two wired elements which, by
moving, act on the fibre in an alternate manner: first they trap it then
they remove it. Depending on the
layout of the teeth, the direction travelled and the speed of the
devices, two conditions are possible, called:
- Carding position which is obtained when the teeth of the wired elements are inclined in an opposite direction and their movement occurs with a certain speed and in a direction that permits a reciprocal grasp of the fibre and then the disentangling of the neps and elimination of trash and dust.
- Position of cleaning or brushing , which is obtained, on the other hand, when the devices have converging teeth and their movement occurs with such a speed and in such a direction to permit the passing of fibre from one organ to another.
Subscribe to:
Posts
(Atom)