For example, If 1 pound of yarn contains 20 hanks of yards, then English cotton count will be 20Ne. Metric system: It is defined as no of hank m per kg. Each process in a spinning mill contributes a part to the evenness. This term is used commonly to express twist level of the yarn. There is no limitation in the length of the thin place.
Better yarn has less thin place. Frequently-occurring thick places exhibit a length that corresponds with the mean staple length of the fibre. It can either be a fiber nep, a seed coat nep or a trash particle. The increase for neps is calculated to a reference length of 1mm. They can be a bunch of entangled fibres commonly not bigger than pin ball head. Micronaire Mic.
A fiber sample of constant weight is measured by passing air through the fibers and measuring the drop in pressure. The micronaire scale has been established empirically with a standard set of cottons and is not linear.
Other factors such as fineness and maturity have an influence on micronaire results. These fibers can be natural fibers cotton or artificial fibers polyester. Final product of spinning is yarn. Spinning is the foundation process and all the subsequent value added processes such as Weaving, Knitting, Garments and Denims are depend upon it.
Any variation in quality of spinning product directly affects the entire value chain. A brief discussion of function of the major machineries used in Square textile Complex has been described below: Blow Room: Blow room is the starting of the spinning operation. It is the section where supplied compressed bale is turn into a uniform lap of particular length.
The basic functions of blow room are opening, cleaning, dust removal, blending and evenly feeding the material on the card. The machineries required to carry out these functions are: 1. Cotton Bale 2. Unicleane or Cleaning Machine 3. Unimix or Mixing Machine 4. Fine Cleaner 5. Condenser 6. Carding 7. It could be automatic or manual.
Unifloc is an automatic bale opener machine that plucks raw cotton in lump form and sends these to clean through air transportation for coarse cleaning. From Figure B , the major parts of automatic bale opener are: 1. Control unit 2. Channel for cable chain 3. Fly duct 4. Swiveling tower 5. Control box 6. Take off unit 7. Suction duct 8. Traversing rails 9.
Bale lay down area Chassis Cleaning Machine: Cleaner machine is an important machine in spinning for opening and cleaning impurities from cotton.
This machine is set normally after Bale Opener machine. Double pin beater 2. Grid bar 3. Mixing is done after the study of the essential properties of fiber like staple length, tensile strength, fineness, uniformity etc. Fibers actually stored in six chambers and mixed up by beating. Storage Section 9. Material exit 2. Separating Vanes Stripper roller 3. Conveyor Belt Take-off roller 4.
Top exhaust air exit Spiked feed lattice 5. Partitions Opening and cleaning unit 6. Downwards exhaust air Waste chamber 7. Intermediate section Conveyor belt drive 8. In this section fine cleaning is done through beating and waste products are separated. Mechanical action on fibers causes some deterioration on yarn quality, particularly in terms of neaps.
Figure: Fine cleaning or uniflex machine and identification of their major parts From figure above the major part of fine cleaner machine: 1.
Inlet duct 7. Feed roll 2. Ventilator 8. Trough 3. Dust cage 9. Grid bar 4. Plain drum Waste box 5. Cleaned cotton outlet duct Laminar chute 6.
The most effective protection here consists of two stages: One for the separation of metals, heavy parts and burning material at the start of the cleaner line and one for the specific separation of foreign parts foreign fibers at the end of the cleaning line. This chute material sends to the carding machine for further processing via chute line. Figure: Rieter condenser unit in blow room From figure above, the major parts of a condenser are: 1.
Material feed 7. Fan 2. Feed funnel 8. Guide plate over take-off roller 3. Perforated drum 9. Protected cover Switch 5. Exhaust air outlet Material delivery 6. Mainly impurities are removed at the intake and the naps and short fibers are removed by action between the cylinder and flat. It is called the heart of cotton spinning because the quality of a yarn is greatly dependent upon the carding machine.
In carding machine, cotton converted into sliver, which is deposited in sliver can. Figure: Carding machine and its major parts. From the figure above, the major parts of a carding machine are: 1. Aero feed 8. Carding profile Waste removal 2. Material distribution device 9. Detaching device 3. Fleece pick-up by cross apron 4. Flat cleaner Stepped rollers 5. Flat Doffer 6. Cylinder Bottom part of the machine 7. Complete covering Also fiber blending can be done at this stage.
Some other tasks of this draw frame are drafting, parallelizing, blending, dust removal etc. Usually, it takes 12 sliver can as input and give one sliver can as output. Breaker Drawing and Finisher Drawing looks similer but the main difference between these two is Finisher Drawing has Auloleveller. Auloleveller is a online monitering system in spinning process and an integral part of the process for better yarn production. Slivers collected from carding have high degree of uneveness and contains infamous piecings.
Autoleveller adjust the draft continuously and maintain consistent hank of sliver. While the basic yarn manufacturing process has remained unchanged for a number of years, processing speeds, control technology and package sizes have increased.
Yarn properties and processing efficiency are related to the properties of the cotton fibres processed. End-use properties of the yarn are also a function of processing conditions.
Typically, mills select bale mixes with the properties needed to produce yarn for a specific end-use. The number of bales used by different mills in each mix ranges from 6 or 12 to over Processing begins when the bales to be mixed are brought to the opening room, where bagging and ties are removed. Layers of cotton are removed from the bales by hand and placed in feeders equipped with conveyors studded with spiked teeth, or entire bales are placed on platforms which move them back and forth under or over a plucking mechanism.
The aim is to begin the sequential production process by converting the compacted layers of baled cotton into small, light, fluffy tufts that will facilitate the removal of foreign matter. This enhances opening and helps regulate the feeding rate. The cleaning machines in mills perform the functions of opening and first-level cleaning.
The card is the most important machine in the yarn manufacturing process. It performs second- and final-level cleaning functions in an overwhelming majority of cotton textile mills. The batt is removed from the screens in an even, flat sheet and then is rolled into a lap. However, labour requirements and the availability of automated handling systems with the potential for improved quality are contributing to the obsolescence of the picker.
The elimination of the picking process has been made possible by the installation of more efficient opening and cleaning equipment and chute-feed systems on the cards. The latter distribute opened and cleaned tufts of fibres to cards pneumatically through ducts. This action contributes to processing consistency and improved quality and reduces the number of workers required. A small number of mills produce combed yarn, the cleanest and most uniform cotton yarn.
Combing provides more extensive cleaning than is provided by the card. The purpose of combing is to remove short fibres, neps and trash so that the resulting sliver is very clean and lustrous.
The comber is a complicated machine composed of grooved feed rolls and a cylinder that is partially covered with needles to comb out short fibres see figure 3. Drawing is the first process in yarn manufacturing that employs roller drafting.
In drawing, practically all draft results from the action of rollers. Containers of sliver from the carding process are staked in the creel of the drawing frame. Drafting occurs when a sliver is fed into a system of paired rollers moving at different speeds. Drawing straightens the fibres in the sliver by drafting to make more of the fibres parallel to the axis of the sliver.
Parallelization is necessary to obtain the properties desired when the fibres are subsequently twisted into yarn. Drawing also produces a sliver that is more uniform in weight per unit of length and helps to achieve greater blending capabilities.
The fibres that are produced by the final drawing process, called finisher drawing, are nearly straight and parallel to the axis of the sliver. Weight per unit length of a finisher-drawing sliver is too high to permit drafting into yarn on conventional ring-spinning systems. The roving process reduces the weight of the sliver to a suitable size for spinning into yarn and inserting twist, which maintains the integrity of the draft strands.
Cans of slivers from finisher drawing or combing are placed in the creel, and individual slivers are fed through two sets of rollers, the second of which rotates faster, thus reducing the size of the sliver from about 2. Spinning is the single most costly step in converting cotton fibres to yarn.
The amount of twist is proportional to the strength of the yarn. The ratio of the length to the length fed can vary on the order of 10 to Bobbins of roving are placed onto holders that allow the roving to feed freely into the drafting roller of the ring-spinning frame.
The spindle holding this bobbin rotates at high speed, causing the yarn to balloon as twist is imparted. In the modern production of heavier or coarse yarns, open-end spinning is replacing ring spinning. A sliver of fibres is fed into a high-speed rotor.
Here the centrifugal force converts the fibres into yarns. There is no need for the bobbin, and the yarn is taken up on the package required by the next step in the process. Considerable research and development efforts are being devoted to radical new methods of yarn production. The roving process is eliminated. Other spinning systems have also eliminated the need for roving, as well as addressing the key limitation of both ring and open-end spinning, which is mechanical twisting.
These systems, air jet and Vortex, use compressed air currents to stabilize the yarn. By removing the mechanical twisting methods, air jet and Vortex are faster and more productive than any other short-staple spinning system.
After spinning, the yarns are tightly wound around bobbins or tubes and are ready for fabric forming. Ply yarns are two or more single yarns twisted together.
Cord is plied yarn twisted together. From Field to Fabric.
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