Showing posts with label Rotor Spinning. Show all posts
Showing posts with label Rotor Spinning. Show all posts
9 March 2013
Raw Material Used in Rotor Spinning
Raw Material Used in Rotor Spinning:
Short staple spinning m/c (up to 60 mm fiber length) require
Fiber Length:
Following m/t can be processed according to Reiter Company
Cotton:
Finer fibers preferred in rotor spinning usually in the range of
Fiber Strength:
Due to poorer exploitation of the fiber substance, fibers of the greatest possible strength .
Dirt & Dust:
The rotor-spinning machine reacts very sensitively to the trash content of cotton. Coarse particles such as husk particles stay caught in the rotor groove. They can prevent yarn formation at this point, & this in turn can lead to an end down or to fiber agglomeration at the particle. This gives a thick place at the agglomeration point & immediately a thin place after this. More trash content also lead to more NEP generation. Small particles also lead to deterioration in quality.
Clean raw m/t is therefore a precondition for spinning of yarn on the rotor spinning m/c. in accordance with recommendations from Reiter, the following residual trash content should not be exceeded in the feed sliver:
Short staple spinning m/c (up to 60 mm fiber length) require
- Cotton (CO)
- Cotton waste ( secondary m/t recycled m/t)
- Cotton noil
- Blends of two or more of these materials.
- Polyester fibers (PES).
- Polyacrylonitrile fiber ( PAC)
- Poly amide fiber (PA)
- Viscose (CA)
- Blends of man-made fibers ( mostly PES/ CV & PAC/CV)
- Blends of cotton & man made fibers ( mostly CO/ PES & CO/CV)
- Fiber strength
- Fiber fineness (optimum fiber fineness)
- Short fiber content
- Variation in fiber length
- Fiber to metal friction
- Residual trash and dust content
Fiber Length:
Following m/t can be processed according to Reiter Company
Cotton:
- Waste <7/8 inches ( for yarns up to 15 tex count)
- Short-staple cotton < 1 inch ( for yarns up to 30 tex count )
- Medium staple cotton < 1 1/8 inches (for yarn up to 17 tex count )
- Staple length up to 60 mm for count = 12 tex yarns
Finer fibers preferred in rotor spinning usually in the range of
- Cotton 2.8 to 4.5 micronaire.
- Man- made fibers 1, 1.2 to 1.7 dtex.
Fiber Strength:
Due to poorer exploitation of the fiber substance, fibers of the greatest possible strength .
Dirt & Dust:
The rotor-spinning machine reacts very sensitively to the trash content of cotton. Coarse particles such as husk particles stay caught in the rotor groove. They can prevent yarn formation at this point, & this in turn can lead to an end down or to fiber agglomeration at the particle. This gives a thick place at the agglomeration point & immediately a thin place after this. More trash content also lead to more NEP generation. Small particles also lead to deterioration in quality.
Clean raw m/t is therefore a precondition for spinning of yarn on the rotor spinning m/c. in accordance with recommendations from Reiter, the following residual trash content should not be exceeded in the feed sliver:
- Up to Ne 6 : 0.3%
- Up to Ne20 : 0.2%
- Up to Ne 30 : 0.15%
- Up to Ne 50 : 0.10%
- Quartz & mineral dust present in cotton causes wear & tear in m/c
- Foreign fibers lead to ends down.
- Honey dew makes fiber to stick to m/c parts & cotton free of honey-due should be used.
- Spin finish should be taken off before feeding to m/c. it acts same as honey due.
- Remnants of the yarn lead to thick places in the yarn, so they should not be used.
15 February 2013
What is Rotor? | Principle of Rotor Spinning | Tasks of the Rotor Spinning Machine
The Rotor:
The
rotor is the main spinning element of the rotor-spinning m/c. Yarn
quality ,character working performance of yarn productivity, & costs
etc. all depend chiefly on the rotor. The most important parameters of
the rotor that exert influence are
Tasks of the Rotor Spinning Machine:
The basic tasks of the rotor spinning machine are
The general principle of rotor spinning is shown in Figure. The input fiber strand is a drawn sliver. A sliver may have more than 20,000 fibers in its cross-section. This means that a yarn of 100 fibers per cross-section will require a total draft of 200. This amount of draft is substantially higher than that of ring spinning. Drafting in rotor spinning is accomplished using a comber roll (mechanical draft) which opens the input sliver followed by an air stream (air draft). These two operations produce an amount of draft that is high enough to reduce the 20,000 fibers entering the comber roll down to few fibers (5-10 fibers). In order to produce a yarn of about 100 fibers per cross-section, the groups of few fibers emerging from the air duct are deposited on the internal wall of the rotor and a fiber ring is formed inside the rotor.
The total draft in rotor spinning is, therefore a combination of true draft from the feed roll to the rotor (in the order of thousands) and a condensation to accumulate the fiber groups into a fiber ring inside the rotor. The total draft ratio is the ratio between the delivery or the take-up speed and the feed roll speed. This should approximately amount to the ratio between the number of fibers in the sliver cross-section and the number of fibers in the yarn cross-section.
- The rotor form
- The groove
- The rotor diameter
- Rotational speed along with
- The rotor bearing
- Co-efficient of friction b/w the fiber & the rotor wall.
- The air-flow conditions inside the rotor
- Liability to fouling
Tasks of the Rotor Spinning Machine:
The basic tasks of the rotor spinning machine are
- Opening (& attenuating) almost to individual fibers (fiber separation).
- Cleaning.
- Homogenizing through back doubling.
- Combining i.e. forming a coherent linear strand from individual fibers.
- Ordering (the fibers in the strand must have an orientation as far as possible in the longitudinal direction).
- Improving evenness through back-doubling.
- Imparting strength by twisting
- Winding.
The general principle of rotor spinning is shown in Figure. The input fiber strand is a drawn sliver. A sliver may have more than 20,000 fibers in its cross-section. This means that a yarn of 100 fibers per cross-section will require a total draft of 200. This amount of draft is substantially higher than that of ring spinning. Drafting in rotor spinning is accomplished using a comber roll (mechanical draft) which opens the input sliver followed by an air stream (air draft). These two operations produce an amount of draft that is high enough to reduce the 20,000 fibers entering the comber roll down to few fibers (5-10 fibers). In order to produce a yarn of about 100 fibers per cross-section, the groups of few fibers emerging from the air duct are deposited on the internal wall of the rotor and a fiber ring is formed inside the rotor.
The total draft in rotor spinning is, therefore a combination of true draft from the feed roll to the rotor (in the order of thousands) and a condensation to accumulate the fiber groups into a fiber ring inside the rotor. The total draft ratio is the ratio between the delivery or the take-up speed and the feed roll speed. This should approximately amount to the ratio between the number of fibers in the sliver cross-section and the number of fibers in the yarn cross-section.
 |
| Rotor Spinning process |
The winding operation in rotor spinning is completely separate from the drafting and the twisting operations. The only condition here is that the yarn is taken up at a constant rate. This separation between winding and twisting allows the formation of larger yarn packages than those in ring spinning.
Sequence of Operation:
The feed stock in form of either card sliver or draw frame sliver from first or second passage drawing. The sliver runs from a can beneath the spinning unit into the feed trumpet. A feed roller grips the sliver & pushes it over the feed through into the region of the opening roller. A spring ensures firm clamping of the sliver by urging the trough towards feed roller. In the event of an end-break, the feed unit is stopped either by stopping the feed roller rotation or by pivoting the in feed trumpet, in each case sliver feed stops automatically. The signal pulse causing this effect is generated by a yarn-sensing arm.
In the in conventional spinning processes, the fiber strand at in feed is maintained as a coherent structure & is merely attenuated during spinning. In rotor spinning, the fiber strand is opened to individual fibers. This task is performed mainly by the opening roller. This small roller which is clothed with needles or saw teeth, combs through the fiber beard projecting from the nip between the feed roller & the tough it transports the plucked fibers to the feed tube. An air flow is needed for further transport of the fibers to the rotor. This is generated by central fan that draws air by suction through leads from each rotor box. To facilitate generation of this under pressure, the rotor box must be hermetically sealed as far as possible. The suction stream in the feed tube lifts the fibers off the surface of the opening roller & leads them to the rotor. In the course of this movement, both the air & the fibers are accelerated because of the convergent form of the feed tubes. This represents a second draft following the nip trough/ opening roller & giving further separation of the fibers. Moreover partial straightening of the fibers is achieved in this air flow. A third draft arises upon arrival of the fibers on the wall of the rotor because the peripheral speed of the rotor is several times as the speed of the fiber. This is a very important feature because it contributes significantly to good orientation of the fibers. The last straightening of the fibers occurs as the fiber slides down the rotor wall into the groove under the influence of the enormous centrifugal forces work within the rotor.
Speed Interrelationship:
Normal & maximum revolutions & speeds are
- Rpm of opening roller :5000 -10000 rpm
- Rpm of rotor up to 100000 rpm
- Delivery speed: up to 200m/min.
- Number of spinning positions per m/c up to 220
- Count range 12- 125 Tex (5 – 50 Ne)
- Draft 25- 400
- Speed of rotation of opening roller 6000- 11000 rpm
- Rotation speed of rotor up tp 120000 rpm
- Rotor diameter 32 -65 mm
- Delivery speed ( m/ min) up to 200
- Package mass up to 5 kg
- Angle of taper 2° - 4° 20’
- Winding angle 29° – 45°
12 February 2013
Process Flow Chart of Rotor Yarn Spinning
Commercial
rotor spinning began in 1967 in Czechoslovakia. Since that time, many
researchers have studied factors that affect rotor spinning of fine
yarns. At the present, the break-even point, i.e., the economical count
beyond which rotor spinning becomes more expensive than conventional
ring spinning, is becoming ever finer, and is now approaching Ne 30 (the
English system is used for yarn count). The alternative count system,
tex or gram/kilometer, is given by tex X Ne = 590.6.
The purpose of this research was to study the interaction between five principal factors known to influence rotor spinning of fine cotton yarns. The factors investigated were raw material, preparation, sliver weight, count, and twist. The study was set up as a factorial design with two replications.
 |
| Rotor spinning machine |
Rotor
spinning process is fully different from carded or combed spinning.
Rotor yarn is coarser than carded or combed yarn. The count of rotor
yarn is very low. Most of rotor yarn count is below 20’s but highest
yarn count may be 40’s .
The general effect of varying any one of these factors on rotor spinning is already well understood. By examining their interactions, however, it was deemed possible to acquire information on a number of other troublesome questions which are enumerated as follows:
1. Is combing beneficial generally, or only at fine counts, or only with long-staple cottons?
2. Is a long-staple cotton generally advantageous, or only at low twist?
3. When a low-micronaire cotton is used, under what conditions, if any, does the higher number of fibers in the yarn cross-section offset the tendency to form neps? Is the net effect of a fine cotton a function of yarn count?
4. To what extent is very high draft undesirable, i.e., should finer slivers be used in spinning fine yarns?
5. Are there high-order interactions, e.g., does fine yarn call for a long combed fiber with a low sliver weight?
6. Are the results of spinning performance consistent with those obtained by measuring yarn properties such as evenness, tenacity and appearance?
The general effect of varying any one of these factors on rotor spinning is already well understood. By examining their interactions, however, it was deemed possible to acquire information on a number of other troublesome questions which are enumerated as follows:
1. Is combing beneficial generally, or only at fine counts, or only with long-staple cottons?
2. Is a long-staple cotton generally advantageous, or only at low twist?
3. When a low-micronaire cotton is used, under what conditions, if any, does the higher number of fibers in the yarn cross-section offset the tendency to form neps? Is the net effect of a fine cotton a function of yarn count?
4. To what extent is very high draft undesirable, i.e., should finer slivers be used in spinning fine yarns?
5. Are there high-order interactions, e.g., does fine yarn call for a long combed fiber with a low sliver weight?
6. Are the results of spinning performance consistent with those obtained by measuring yarn properties such as evenness, tenacity and appearance?
Flow Chart of Rotor Yarn Spinning
Fiber/Bale → Blow Room → Lap/Chute
↓
Lap/Chute → Carding → Sliver (Carded)
↓
Carded Sliver → 1st Drawing frame → Drawing Sliver
↓
Drawing Sliver → 2nd Drawing frame → Drawing Sliver
↓
Drawing Sliver → Rotor Spinning → Rotor Yarn
↓
Winding
↓
Reeling
↓
Bundling
↓
Bailing
↓
Lap/Chute → Carding → Sliver (Carded)
↓
Carded Sliver → 1st Drawing frame → Drawing Sliver
↓
Drawing Sliver → 2nd Drawing frame → Drawing Sliver
↓
Drawing Sliver → Rotor Spinning → Rotor Yarn
↓
Winding
↓
Reeling
↓
Bundling
↓
Bailing
17 November 2012
Different Types of Yarn Spinning System | Open-end Spinning | Ring Spinning, Rotor Spinning, Wet Spinning, Dry Spinning, Air-jet Spinning, Centrifugal Spinning, Flyer Spinning, Melt Spinning, Reaction Spinning, Flash Spinning, Draw-Spinning, Dispersion Spinning, Friction Spinning, Break Spinning
Spinning:
In the spinning of
man-made filaments, fibre-forming substances in the plastic or molten
state, or in solution, are forced through the holes of a spinneret or
die at a controlled rate. There are five general methods of spinning
man-made filaments i.e. dispersion spinning, dry spinning, melt
spinning, reaction spinning, and wet spinning, but combinations of these
methods may be used.
In the bast and leaf-fiber industries, the terms 'wet spinning' and 'dry spinning' refer to the spinning of fibres into yarns in the wet state and in the dry state respectively.
Open-end Spinning;
The
present participle of the verb 'to spin' used verbally, adjectivally,
or as a noun, meaning process or the processes used in the production of
yarns or filaments.
The term may apply to:
(i) The drafting and, where appropriate, the insertion of twist in natural or staple man-made fibres to form a yarn;
(ii) The extrusion of filaments by spiders or silkworms; or
(iii) The production of filaments from glass, metals, fibre-forming polymers or ceramics.
The term may apply to:
(i) The drafting and, where appropriate, the insertion of twist in natural or staple man-made fibres to form a yarn;
(ii) The extrusion of filaments by spiders or silkworms; or
(iii) The production of filaments from glass, metals, fibre-forming polymers or ceramics.
 |
| Ring spinning |
In the bast and leaf-fiber industries, the terms 'wet spinning' and 'dry spinning' refer to the spinning of fibres into yarns in the wet state and in the dry state respectively.
Open-end Spinning;
Break Spinning:
A spinning system in which sliver feed stock is highly drafted, ideally to individual fibre state, and thus creates an open end or break in the fibre flow. The fibres are subsequently assembled on the end of a rotating yarn and twisted in. Various techniques are available for collecting and twisting the fibres into a yarn, the most noteworthy being rotor spinning and friction spinning.
Rotor Spinning:
A method of open-end spinning which uses a rotor (a high-speed centrifuge) to collect individual fibres into a yarn is known as Rotor spinning. The fibers on entering a rapidly rotating rotor are distributed around its circumference and temporarily held there by centrifugal force. The yarn is withdrawn from the rotor wall and, because of the rotation, twist is generated.
Friction Spinning:
A method of open-end spinning which uses the external surface of two rotating rollers to collect and twist individual fibres into a yarn is known as Friction spinning. At least one of the rollers is perforated so that air can be drawn through its surface to facilitate fibre collection. The twisting occurs near the nip of the rollers and, because of the relatively large difference between the yam and roller diameters, high yarn rotational speeds are achieved by the friction between the roller surface and the yarns.
Air-jet Spinning:
A system of staple-fibre spinning which utilizes air to apply the twisting couple to the yarn during its formation is known as Air-jet spinning. The air is blown through small holes arranged tangentially to the yarn surface and this causes the yarn to rotate. The majority of systems using this technique produce fasciated yarns, but by using two air jets operating in opposing twist directions it is possible to produce yarns with more controlled properties but of more complex structure.
Centrifugal Spinning:
A method of man-made fiber production in which the molten or dissolved polymer is thrown centrifugally in fibre form from the edge of a surface rotating at high speed. The term is also used to describe a method of yarn formation involving a rotating cylindrical container, in which, the yarn passes down a central guide tube and is then carried by centrifugal force to the inside of a rotating cylindrical container.
Dispersion Spinning:
A process in which the polymers that tend to an infusible, insoluble, and generally intractable character (e.g., polytetrafluoroethylene) are dispersed as fine particles in a carrier such as sodium alginate or sodium xanthate solutions is known as Dispersion spinning. These permit extrusion into fibers, after which the dispersed polymer is caused to coalesce by a heating process, the carrier being removed either by heating or by a dissolving process.
Draw-Spinning:
A process for spinning partially or highly oriented filaments in which the orientation is introduced prior to the first forwarding or collecting device.
Dry Spinning (man-made fiber production):
The spinning process involving conversion of a dissolved polymer into filaments by extrusion and evaporation of the solvent from the extrudate is known as Dry spinning.
Flash Spinning:
A modification of the accepted dry-spinning method in which a solution of a polymer is extruded at a temperature well above the boiling point of the solvent such that on emerging from the spinneret evaporation occurs so rapidly that the individual filaments are disrupted into a highly fibrillar form.
Flyer Spinning:
A spinning system in which yarn passes through a revolving flyer leg guide on to the package is known as Flyer spinning. The yarn is wound-on by making the flyer and spinning package rotate at slightly different speeds.
Melt Spinning (man-made fiber production):
The spinning process involving conversion of a molten polymer into filaments by extrusion and subsequent cooling of the extrude is known as Melt spinning.
Reaction Spinning (man-made-fiber production):
A process in which polymerization is achieved during the extrusion of reactants through a spinneret system.
Ring Spinning:
A spinning system in which twist is inserted in a yarn by using a revolving traveller is known as Ring spinning. The yarn is wound on since the rotational speed of the package is greater than that of the traveller.
Wet Spinning (man-made-fiber production):
The spinning process involving conversion of a dissolved polymer into filaments by extrusion into a coagulating liquid is known as Wet spinning. The extrusion may be directly into the coagulating liquid or through a small air-gap. In the latter case it may be known as dry-jet wet spinning or air-gap wet spinning.
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A spinning system in which sliver feed stock is highly drafted, ideally to individual fibre state, and thus creates an open end or break in the fibre flow. The fibres are subsequently assembled on the end of a rotating yarn and twisted in. Various techniques are available for collecting and twisting the fibres into a yarn, the most noteworthy being rotor spinning and friction spinning.
Rotor Spinning:
A method of open-end spinning which uses a rotor (a high-speed centrifuge) to collect individual fibres into a yarn is known as Rotor spinning. The fibers on entering a rapidly rotating rotor are distributed around its circumference and temporarily held there by centrifugal force. The yarn is withdrawn from the rotor wall and, because of the rotation, twist is generated.
Friction Spinning:
A method of open-end spinning which uses the external surface of two rotating rollers to collect and twist individual fibres into a yarn is known as Friction spinning. At least one of the rollers is perforated so that air can be drawn through its surface to facilitate fibre collection. The twisting occurs near the nip of the rollers and, because of the relatively large difference between the yam and roller diameters, high yarn rotational speeds are achieved by the friction between the roller surface and the yarns.
Air-jet Spinning:
A system of staple-fibre spinning which utilizes air to apply the twisting couple to the yarn during its formation is known as Air-jet spinning. The air is blown through small holes arranged tangentially to the yarn surface and this causes the yarn to rotate. The majority of systems using this technique produce fasciated yarns, but by using two air jets operating in opposing twist directions it is possible to produce yarns with more controlled properties but of more complex structure.
Centrifugal Spinning:
A method of man-made fiber production in which the molten or dissolved polymer is thrown centrifugally in fibre form from the edge of a surface rotating at high speed. The term is also used to describe a method of yarn formation involving a rotating cylindrical container, in which, the yarn passes down a central guide tube and is then carried by centrifugal force to the inside of a rotating cylindrical container.
Dispersion Spinning:
A process in which the polymers that tend to an infusible, insoluble, and generally intractable character (e.g., polytetrafluoroethylene) are dispersed as fine particles in a carrier such as sodium alginate or sodium xanthate solutions is known as Dispersion spinning. These permit extrusion into fibers, after which the dispersed polymer is caused to coalesce by a heating process, the carrier being removed either by heating or by a dissolving process.
Draw-Spinning:
A process for spinning partially or highly oriented filaments in which the orientation is introduced prior to the first forwarding or collecting device.
Dry Spinning (man-made fiber production):
The spinning process involving conversion of a dissolved polymer into filaments by extrusion and evaporation of the solvent from the extrudate is known as Dry spinning.
Flash Spinning:
A modification of the accepted dry-spinning method in which a solution of a polymer is extruded at a temperature well above the boiling point of the solvent such that on emerging from the spinneret evaporation occurs so rapidly that the individual filaments are disrupted into a highly fibrillar form.
Flyer Spinning:
A spinning system in which yarn passes through a revolving flyer leg guide on to the package is known as Flyer spinning. The yarn is wound-on by making the flyer and spinning package rotate at slightly different speeds.
Melt Spinning (man-made fiber production):
The spinning process involving conversion of a molten polymer into filaments by extrusion and subsequent cooling of the extrude is known as Melt spinning.
Reaction Spinning (man-made-fiber production):
A process in which polymerization is achieved during the extrusion of reactants through a spinneret system.
Ring Spinning:
A spinning system in which twist is inserted in a yarn by using a revolving traveller is known as Ring spinning. The yarn is wound on since the rotational speed of the package is greater than that of the traveller.
Wet Spinning (man-made-fiber production):
The spinning process involving conversion of a dissolved polymer into filaments by extrusion into a coagulating liquid is known as Wet spinning. The extrusion may be directly into the coagulating liquid or through a small air-gap. In the latter case it may be known as dry-jet wet spinning or air-gap wet spinning.
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15 November 2012
Comparison Between Rotor Spinning and Ring Spinning
tor spinning process is fully different from carded or combed spinning.
Rotor yarn is coarser than carded or combed yarn. The count of rotor
yarn is very low. Most of rotor yarn count is below 20’s but highest
yarn count may be 40’s . Coarser fabric is formed by rotor yarn. Most of
the jeans or pant is made by rotor yarn. Denim is fully depends on
rotor yarn. The price of rotor yarn fabric is very low than combed and
carded yarn fabric.
Comparison of Rotor Spun Yarn with the Ring Spun Yarn :
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 |
| Rotor spinning |
 |
| Ring spinning |
- Breaking strength lower than ring spun Yarn
- CV% of strength better than ring spun yarn
- Elongation at break higher than ring spun yarn
- Mass irregularity ( over short lengths) better than ring spun yarn
- Imperfection index lower than ring spun yarn
- Volume greater than ring spun yarn
- Abrasion resistance higher than ring spun yarn
- Stiffness higher than ring spun yarn
- Handle harder
- Power consumption less than ring spun yarn
- Possible yarn counts rotor Ne 3 – 60 and Ring Ne 6 – 200
- Energy consumption with productivity lower as compared to ring m/c.
- Surface rougher than ring yarn
- Hariness lower than ring yarn
- Lusture on the dull side
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