Fiber groups
There are two main groups of fibers used in short staple spinning.
1- Natural fibers
2- Man made, or manufactured fibers
In the natural group, cotton is
the predominant fiber, followed by flax. Of course there are many other natural
fibers, but they are of lesser interest to the staple spinning industry.
In the manufactured fiber group, polyesters, rayons and acrylics are the main sources for staple spinning.
Manmade fibres
⦁ Polyester
⦁ Polyamide
⦁ Nylon
⦁ Viscose,
⦁ Kevlar, a high-performance fibre
⦁ Nomex, a high-performance fibre.
Cotton : There are
approximately 80 countries throughout the world that produce cotton. Many use
the fiber locally but the majority sells some fibers on the world market. The
growing conditions of each region can have a significant effect upon the
variation of fiber properties, the cleanliness, neppiness, stickiness and the
contamination. A spinner’s change from one source to another can have a
dramatic effect on a plant’s efficiency.
Natural fibre
·
Cotton
·
Silk
·
Fur
·
Jute
·
Flax
·
Wool
·
Kapok
·
Hemp
Fineness :The fineness of cotton is frequently
the most important fiber property, particularly for ring spun yarns. The
spinning of fine yarn is limited to the number of fibers in the cross section,
which is proportional to the beauty of the fiber.
Spinnding-Limit:
Yarn crossection
Number of fibers =
tex-yarn / tex-fiber
Longstapel (wool & blends)
= 40 fibers
M-made 3.3dtex 50 –60 -80mm = 55
fibers
M-made 1.3-1.7 dtex/ 38 -40mm = 70
fibers
Cotton Ringyarn (min. 40)
= 70 fibers
Cotton Rotoryarn
= 100
fibers
Also, the higher the
number of fibers in the cross-section, the more uniform the yarn can be. Yarn
strength is increased and weak places reduced with finer fiber and subsequently
downstream processing efficiencies can be improved. The cotton fiber is not normally
circular in cross section and cannot be defined by its diameter.
Micronaire is widely used to indicate fineness. This value is obtained by
measuring the airflow through a plug of cotton. As fine as cotton is, it has
lower air flow and lower microner value. On the other hand, man made
fibers can be categorized by weight/unit length i.e. decigram/km
=dtex.
Below is a measure of micronier values and finance equations.
Scale Micronaire dtex
(Mic x 0.394)* denier
Mic very fine = up to 3.1 up to 1.22
up to 1.35
Mic fine =
3.2 - 3.9 1.26 - 1.54 1.39 - 1.70
average Mic =
4.0 - 4.9 1.58 - 1.93 1.74 - 2.12
Mic coarse = 5.0 - 5.9 1.97 - 2.32 2.17
- 2.55
Mic very coarse = 6.0 and above 2.4 and
above 2.64 and above
Fibers used in Short Staple Spinning
General information :
The cost of fibers used in the production of
yarn accounts for approx. 50% of the production costs. Consequently, the
skillful selection and use of the raw materials has a great impact on the success
of a spinning plant. The correct setting of machines is, to a large extent,
dependent upon the fibers being processed. A thorough knowledge of fibers and
their properties is essential for the spinner. Fibers fall into one of two
groups, natural fibers such as cotton, flax and wool, and the man made fibers
such as polyester, viscose/rayon, nylon, acrylic and polypropylene. Each fiber
type has its special characteristics that make it perform differently from
other types.
Fiber properties directly influence the end
products in the following ways:
- 1. strength
- 2. yarn count
- 3. productivity
- 4. uniformity
- 5. fabric hand
- 6. luster
- 7. drape
- 8. absorbency / comfort
- 9. easy care properties
Some of the distinguishing features of the different fibers
are given in the following sections.
Fiber length
Cotton length is not a definite measure. Any sample of
cotton taken from the bale, or taken during the preparation of spinning, will
be divided into long fibers and short fibers with similar fiber lengths, which
are broken during mechanical operations - see example below. ۔
The USTER® AFIS instrument measures each fiber
separately and, therefore, all the information is available for the staple
diagram attached at the end.
This example shows different parameters, such as pper upper
quartile length U (UQL) and short fiber content. The length of UQL fiber is 25.
The term "upper quartile" indicates that the value is calculated in
the upper quarter of the main diagram.
The basic length of the cotton (clasp length) is a basic
feature in determining the price of cotton. Long is the key value. The length
of the fiber in spinning plants (2.5%) needs to be properly aligned with the
machines where the fibers are controlled in the nip zone, i.e. in the feed
plate of the card and in the drawing process and in the spinning draft zone. In
order
The length of the fiber in the spinning plant has a direct
effect:
- Yarn strength and uniformity
- Eliminate spinning limit and bottom rate
- Production speed and machine performance
Also the presence of short fibers, less than 1/2 1 or 12.5
mm has a negative effect on them:
- Uncontrolled in the drafting process which produces
illegal yarn
- Excessive fly production around machines
- Lost or lost, which is a costly process
- Create bees and lizards in flow operations.
Cotton staple diagram showing various important
measuring points.
The critical length commonly referred to in plants is the
main part of the "classer", which can be grouped as follows.
Types: Category key length
·
Extra Length
Important 1 13/32 and above
·
Long key 1 5/32² to 1
3/8²
·
Medium key 1 1/32² to
1 1/8²
·
Short staples 1² or
less
The rotor spinning is not sensitive to short fiber material
and can handle short fiber effectively in spinning coarse and medium yarns.
Color spinning, air jet and vertex systems require longer lengths using a
high-draft apron system for medium and fine yarn counting, and much less than
removing short fibers through the combing process to produce fine counts. There
is benefit.
No comments:
Post a Comment