III. Production Process:
1. Spinning Department:
Spinning is the process of conversion of fiber to yarn
Process flow of spinning department:
LAYOUT OF SPINNING DEPARTMENT:
Blow room (opening, cleaning &
blending)
The cotton fiber grows in the seedpod or boll, of the cotton plant. Each fiber is a single elongated cell that is flat, twisted, and ribbon like with a wide inner hollow (lumen).It is composed of about 90 percent cellulose and about 6 percent moisture;
the remainder consists of natural impurities. The outer surface of the fiber is covered with a protective wax like coating which gives the fiber a somewhat adhesive quality.
Bale of about 165-170 kg comes into spinning mill
Types of cotton Arvind Mills use:
1. Pakistan Cotton 2. J34 SG
i. (It is a selection from non descriptive hirustum mixtures.
Re-selection from Bikaneri Narma. It is sown in the months of April/May and the crop is ready for picking by October/December.. J34RG and SG are grown in the states of Punjab, Haryana and Rajasthan and total production per annum is around 2.6 million bales of each of 170 Kg.)
3. Shankar-6 Gujarat cotton
i. It is sown in the month of June-July and is ready for picking in November and may extend upto February. It is cultivated in an area of 4.4 million Acres in the state of Gujarat.
4. Organic cotton
a. (Organic cotton is being produced in-house by arvind mills, and also being procured from fully organic certified farms, as some environment
conscious customers prefer to use it.
b. Arvind’s organic cotton contract farming project is located in the cotton growing belt district of Maharashtra; Akola. )
Blow room:
Process flow of blow room:
a) BLENDING
Machine used : Blendomat machine by Truetzschler
Model no. : BDT 019/2300 Bale layout: Both sides (2 rows) Number of bales: 50-60
Weight of bales: 110-167 kg Mode of bale laying: Manual
Material in process: Cotton with seeds and impurities
bale opener or cotton plucker
GBR cotton opener
axi flow cleaner
MPM multiple mixer
ASTA particle
cleaner Rn cleaner RSK cleaner Dustek
Steps:
Cotton is passed from bales and then to apron. Apron moves cotton to blending apron.
Blending apron has sharp spikes the raise cotton until part of it is knocked off by the roll.
Some of the cotton stays on apron.
The cotton knocked back by roll and continues to blend until picked up again by apron.
Another roll strips off cotton that was not knocked back by previous roll.
Cotton falls on conveyor belt and is carried to next process that is blending through an overhead duct.
Why it’s been done?-
It is necessary so as to obtain uniformity of fiber quality
b) OPENING
Machine used : GBR cotton opener- opens about 400 kg/hr
Steps:
Lint cotton falls on apron and passes between feeder rolls to beater cylinder. The rapidly whirling beater blades take off small tufts of cotton, knock out trash, and loosen up the mass.
The two screen rolls are made of screen material and air is sucked out of them by fan.
This draws the cotton from beater and condenses it on the surface of the screen rolls from which it is taken and passed on by the small rolls.
Air suction through cotton takes out dirt and trash. Conveyor belt passes cotton to another type of beater. From beater the cotton passes to a conveyor and is carried to picker.
Why it’s been done?-
It is necessary in order to loosen hard lumps of fiber and disentangle them; cleaning is required to remove trash such as dirt, leaves, burrs, and any remaining seeds.
GBR- Here the cottons are fed for homogenous mixtures and for removing dirts.MPM-8 – it has got 8 chambers. Generally used for homogenous mixture of fibers like while harvesting some cotton are from matured plants and some re not. So that it will affect the fabric. So, after homogenous mixing all will be the same.
c) Axi-flow cleaner-
This is fitted with beaters .Cotton moves from GBR to axiflow by suction and impurities fall below in a bin under the gravitational pull.Objective of AFC is separation of heavy parts (impurities) from cotton.The opened up mass of fiber rotates around two cleaning rollers (beaters) with cylinder steel pins which beat the fiber material, allowing the coarse particles to be separated.The time (in hours) of the passage of material can be regulated The speed range of the beaters varies from 400-600 rpm
Machine make: Trutzschler (Germany) Model: 052-2502
Pressure: 50-75 bar
Major parts: Two metallic perforated cylinders and waste collector
d) MPM multiple mixer-
Fitted with eight beaters. This sucks cotton from axiflowand pumps to asta meanwhile sorting the cotton fibers.Generally used for homogenous mixture of fibers
Make: Trutzschler
Model: 10236
Motor speed: 1750 rpm
Opening rolls speed: 800-850 m/min Number of chambers: 10
Output: 30-36%
Pressure: 350 bar
Major parts: This machine consists of material feed, reserve tank, reserve tank flaps, optical sensor delivery, rollers, and
material suction funnel.
e) ASTA:
Objective of ASTA is Heavy trash separation from cotton. The air and material enters the separation tank in a stream via upper channel and hit baffle plates. Heavy particles are removed away from the lighter fibers by negative acceleration and the force of gravity. The lower channel generates an opulent air stream in the area of baffle plates, which guides the fibers to the outlet.
Make: Trutzschler (Germany)
Model: ASTA 800
Principle: principle of aerodynamics
f) DUSTEX:
Dust removal is not an easy operation since the dust particles are completely enclosed in the flocks & hence are back during suction. The suction units remove dust 64% dust.
Make: Trutzschler (Germany)
Model: CVT-4 1600
No. of machines: 2
Cleaning efficiency: 64%
Carding:
Number of machines: 14
Make: Trutzschler (Germany)
Model: DK 803
Humidity: 56.5%
Temperature: 33.3 degree Celsius Production: 80 kg/hr.
Card cleaning efficiency: 62-67%
CV%: 1.2-1.7
Front Delivery speed: 210-240 meters per minute
Pressure: 325 pas
Carding is the process of removing impurities from fibers and producing a carded sliver of parallelized and straightened fibers
Before the raw stock can be made into yarn, the remaining impurities must be removed, the fibers must be disentangles, and they must be straightened.
The straightening process puts the fibers into somewhat parallel CARDING.
The work is done by carding machine.
The lap is passed through a beater section and drawn on rapidly revolving cylinder covered with very fine hooks or wire brushes slowly moves concentrically above this cylinder
As the cylinder rotates, the cotton is pulled by the cylinder through the small gap under the brushes; the teasing action removes the remaining trashes, disentangles the fibers , and arranges them in a relatively parallel manner in form of a thin web.
This web is drawn through a funnel shaped device that molds it into a round rope like mass called card sliver.
Card sliver produces carded yarns or carded cottons that are serviceable to produce denim fabrics.
After carding, the carded slivers go to the draw frame At Arvind mills:
No of carding machines: 14 machines
Brand name of machine: Trutzschler
Drawing
Drawing is the process where the fibres are blended, straightened and the number of fibres in the sliver increased in order to achieve the desired linear density in the spinning
process. The drawing process also improves the uniformity or evenness of the sliver. The number of drawing passages utilised depends on the spinning system used and the end products
In arvind mills, the sliver is drawn through the draw frame twice.
Draw frame used : Padamatex Total of 12 draw frames at the plant
1ST PASSAGE: parallel alignment of fibers, 6 slivers converted into one
2nd PASSAGE: output of the second passage of draw frame goes into open end/rotar spinning
Roving
In preparation for ring spinning, the sliver needs to be condensed into a finer strand known as a roving before it can be spun into a yarn The roving frame draws out the sliver to a thickness of a few millimetres and inserts a small amount of twist to keep the fibres together. The drafted twisted strand is wound onto a bobbin which is then transported to the ring frame and used as the feed package for spinning yarn.
Roving does not take place at Arvind Mills, as open end spinning is used, not ring spinning
Spinning:
The plant at Naroda works entirely on open end spinning technology/rotar spinning and produces 5400 to 5500 tonnes of yarn a month with 5472 rotars being around on campus.
The speed of the rotar roll varies from 80,000 rpm to 130,000 rpm.
Machine installed :autocoro comb+spin technology
Corolab- automated yarn monitoring system(automatic detection of defects by drop wire technology)
The maximum count of yarn is 20
Open end spinning:
Rotor Spinning is a more recent method of yarn formation compared to Ring Spinning.
This is a form of open-end spinning where twist is introduced into the yarn without the need for package rotation. Allowing higher twisting speeds with a relatively low power cost.
In rotor spinning a continuous supply of fibers is delivered from delivery rollers off a drafting system or from an opening unit.
The fibres are sucked down a delivery tube and deposited in the groove of the rotor as a continuous ring of fibre. The fibre layer is stripped off the rotor groove and the resultant yarn wound onto a package.
The twist in the yarn being determined by the ratio of the rotational speed of the rotor and the linear speed of the yarn.
Sliver is fed into the machine and combed and individualized by the opening roller.
The fibres are then deposited into the rotor where air current and centrifugal force deposits them along the groove of the rotor where they are evenly distributed.
The fibers are twisted together by the spinning action of the rotor, and the yarn is continuously drawn from the center of the rotor. The resultant yarn is cleared of any defects and wound onto packages.
The production rates of rotor spinning is 6-8 times higher than that of ring spinning and as the machines are fed directly by sliver and yarn is wound onto packages ready for use in fabric formation the yarn is a lot cheaper to produce.
Rotor spun yarns are more even, somewhat weaker and have a harsher feel than ring spun yarns.
Rotor spun yarns are mainly produced in the medium count (30 Ne, 20 tex) to coarse count (10 Ne, 60 tex) range.
The yarn is wound on a big package of about 4 kg.
The use of this system has two basic advantages. It is fed by sliver, not as with the ring frame by roving, and so eliminates the speed frame from the process line. It can also be modified to remove any remaining trash, thereby improving the yarn quality.
Ring Spinning Open-end Spinning
Bobbin rotates constantly for insertion of twist Spool does not need to be rotated to insert twist Cannot handle spools of bigger size Much larger spools can be wound
Can spin finer yarns 3-5 times faster than ring spinning
Uniform and strong yarn Uniform but flexible yarn with better dye ability
Combed yarns (finer) Carded yarns (coarser)
Yarns for varied applications Yarns for heavier fabrics such as denims, towels and poplins
Stronger 20% more twisted but 15-20% weaker as the yarn
is coarser
Suitable for all staple fibres Not suitable for man-made staple fibre spinning except rayon as the fibre finish clogs the rotor