Principle of Winding Machine


There are two widely used types of winding machine:

1.) drum winders (used to wind staple-spun yarns into random-wound packages)

2.)precision winders (for winding filament yarns into precision-wound packages).

1.) drum winders

They are also called as “Random Winders”. Drum-winding machines rotate the forming package through surface contact with a cylindrical drum, and the yarn is traversed either by an independent traverse, typically a wing cam, or by grooves in the drum. Figure  1   illustrates the two types of traverse systems

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Fig 1: Winding traverse motion

  • Wing Cam

There are several different independent traverse systems, but the simplicity of the wing cam makes it a useful example to describe. As shown, the end, A, of a yarn guide bar moves the yarn while the other, B, is made to move around the periphery of the cam, traveling one circuit of the periphery per revolution of the camshaft. As B makes one circuit of the cam, A reciprocates, moving the yarn through a return traverse (i.e., double traverse) along the length of the bobbin. The reciprocating yarn guide limits the winding speed because of the inertia on reversals. A very high rate of traverse is impeded by the mechanics of the guide system, since forces of 16 to 64 times the weight of the yarn guide can be present during the reciprocating action. The reciprocating guide can be replaced by a spirally grooved traverse roller, which moves the yarn along the traverse length. In this case, only the yarn undergoes reversal as it is held in the traversing groove of the rotating roller, and speeds in excess of 1500 m/min can be achieved. A further advantage of the grooved traverse roller is that, as a result of tension, the yarn being wound enters the groove without the need for threading up as is required with the independent traverse system.

  • Grooved Drum

With the grooved drum system, the surface speed of the drum, and the traverse speed are kept constant. A continuous helical groove (i.e., interconnected clockwise and counter clockwise helical grooves) around the drum circumference guides the yarn along the traverse length as the yarn is wound onto the bobbin. A continuous helix has points of crossover of the clockwise and counter clockwise helices. To retain the yarn in the correct groove during its traverse, particularly at the intersections, one groove is made deeper than the other, and the shallower groove is slightly angled.

2.)precision winders

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They are also known as Spindle driven Winders. the Principle of precision winder is as shown in figure.

With precision winders, the package is mounted onto a drive spindle, and a reciprocating yarn guide, driven by a cylindrical cam coupled to the spindle drive, is used to move the yarn along the traverse length. The reciprocating yarn guide limits the winding speed because of the inertia on reversals.

The term precision refers to the control of positioning each layer of yarn as it is wound onto the bobbin. There is a precise ratio of spindle to traverse speed. Therefore, as the package diameter increases, the wind and TR are kept constant.

DREF Spinning


  • Introduction

Friction (DREF) spinning system is an Open-end and or Core sheath type of spinning system. Along with the frictional forces in the spinning zone the yarn formation takes place. The DREF spinning system is used to produce yarns with high delivery rate(about 300mpm). Still it has to gain its importance with the growth along with technical textiles in India. Amongst the spinning systems, DREF provides a good platform for production of core spun yarns due its spinning principle.It offers less spinning tension to the core and core will be positioned exactly at the centre of the yarn.
Development of DREF core-spun yarns unveils a path for new products including high performance textiles, sewing threads and in the apparels due to its exceptional strength, outstanding abrasion resistance, consistence performance in sewing operation, adequate elasticity for the stretch requirements, excellent resistance to perspiration, ideal wash  and wear performance and permanent press.

  • Principle of Friction (DREF) spinning Systems

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The friction spinning system consists of opening & individualization of fibres from slivers, reassembling of individualized fibres, twisting and winding of yarn. The figure 1 describes the DREF spinning principle where the opened fibres made roll with an aid of a mechanical roller for reassembling and twisting. Due to separate yarn winding and method of twist insertion, it has capability to go for high production rate.

  • DREF 1

DREF-1 friction spinning system was developed in 1973 by Dr.Fehrer.A.G. of Austria.The schematic diagram of DREF 1 spinner is shown in the figure 2.The fibres were opened with an opening roller and allowed to fall on a single perforated cylindrical drum slot ,which has negative pressure for fibre collection.The rotation of the drum impart twist to fibre assembly .

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The ratio of perforated drum to yarn surface is very large, hence the drum speed can be kept relatively low, even if one takes the unavoidable slippage into account. Due to the absence of positive control over the fibres assembly, slippage occurred between the fibre assembly and perforated roller, which reduced twist efficiency. Hence this development could not be commercialized.

  • DREF-2image

This is the development with earlier machine. DREF-2 was exhibited in the year 1975 at ITMA exhibition. The feasibility of using two perforated rotating cylinders, (as fibre collecting means), while at the same time the spinning-in of fibres into yarn occurred. It operates on the basis of mechanical/aerodynamic spinning system with an internal suction and same direction of drums rotation. The schematic diagram of the DREF-2 friction spinner is shown in the figure3. Drafted slivers are opened into individual fibres by a rotating carding drum covered with saw tooth type wire clothing. The individualized fibres are stripped off from the carding drum by centrifugal force supported by an air stream from the blower and transported into the nip of two perforated friction drums where they are held by suction. The fibres are sub-sequentially twisted by mechanical friction on the surface of the drums. Suction through the perforations of the drums assists this process besides helping in the removal of dust and dirt, thereby contributing to production of cleaner yarn. The low yarn strength and the requirement of more number of fibres in yarn cross-section(minimum 80-100 fibres) were restricted the DREF-2 spinning with
coarser counts (0.3-6s Ne).

  • DREF-3

The DREF-3 machine is the next version of DREF 2 for improving the yarn quality came to the market in the year 1981.Yarns up to 18s Ne. can be spun thro this system.

This is a core-sheath type spinning arrangement. The sheath fibres are attached to the core fibres by the false twist generated by the rotating action of drums. Two drafting units are used in this system, one for the core fibres and other for the sheath fibres. This system produces a variety of core-sheath type structures and multi-component yarns, through selective combination and placement of different materials in core and sheath. Delivery rate is about 300 m/min. DREF 3 schematic diagram is shown in the figure 4.

  • DREF-5

It was developed by Schalafhorst, Suessen and Fehrer Inc. The range of count to be spun from this system is from 16’s to 40’s Ne.Production speed is up to 200m/min.The schematic diagram of the DREF 5 is shown in the figure 5. The individualized fibres from a single sliver are fed through a fibre duct into the spinning nip at an angle to the yarn axis, so that they are stretched as far as possible, when fed into the nip[7]. This spinning system was not commercialized due to some reasons.

  • DREF-2000

It is the latest development in friction spinning demonstrated in ITMA 99. DREF-2000 employs a rotating carding drum for opening the slivers into single fibres and a specially designed system being used for sliver retention. The fibres stripped off from front the carding drum by centrifugal force and carried into the nip of the two perforated spinning drums. The fibres are subsequently twisted by mechanical friction on the surface of the drums, which rotates in the same direction. The process assisted by air suction through the drum perforations. Insertion of twist in ‘S’ and ‘Z’ direction is possible without mechanical alterations to the machine. Yarns upto 14.5s Ne can be produced at speeds of 250 m/min.

  • DREF-3000

In the ITMA 2003, the first public appearance of the DREF 3000 was made. The yarn can be spun form 0.3Ne to 14.5Ne.The features of DREF 3000 includes a drafting unit and opening head with infinitely variable drive control, spinning units with two infinitely variable suction spinning drums, take-off and winding units with infinitely variable speeds and filament guide with monitoring device. The drafting unit can handle all types of synthetic fibres, special fibres such as aramid, FR and pre-oxidized fibres, polyimides, phenol resin fibres (e.g. Kynol), melamine fibres (e.g. Basofil), melt fibres (e.g. PA, PES, PP), natural fibres (wool, cotton, jute, linen, flax, etc.), as well as glass fibres in blends with other materials. The DREF 3000 processes these fibres in the form of slivers composed of one type of fibre, or using slivers with differing fibre qualities at one and the same time. Slivers with a homogenous fibre mixture can also be employed. DREF 3000 core yarns offer high output, breakage-free spinning and weaving mill operation and thus up to 95% efficiency can be achieved.

  • Yarn formation in Friction spinning system

The mechanism of yarn formation is quite complex. It consists of three distinct operations, namely: Feeding of fibres, Fibres integration and Twist insertion.

  • Feeding:

The individualized fibres are transported by air currents and deposited in the spinning zone. The mode of fibre feed has a definite effect on fibre extent and fibre configuration in yarn and on its properties. There are two methods of fibre feed 1) Direct feed and 2)Indirect feed.

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In case of direct feed, fibres are fed directly onto the rotating fibre mass that outer part of the yarn tail. In indirect feed, fibres are first accumulated on the in-going roll and then transferred to the yarn tail. Figure 7 (a) and (b) are showing the above methods of fibre feed.

  • Fibres Integration:

The fibres through feed tube assembles onto a yarn core/tail within the shear field, is provided by two rotating spinning drums and the yarn core is in between them. The shear causes sheath fibres to wrap around the yarn core. The fibre orientation is highly dependent on the decelerating fibres arriving at the assembly point through the turbulent flow. The fibres in the friction drum have two probable methods for integration of incoming fibres to the sheath. One method, the fibre assembles completely on to perforated drum before their transfer to the rotating sheath. In the other method, fibres are laid directly on to rotating sheath.

  • Twist insertion:

There has been lot of deal with research on the twisting process in friction spinning. In friction spinning, the fibres are applied twist with more or less one at a time without cyclic differentials in tension in the twisting zone. Therefore, fibre migration may not take place in friction spun yarns. The mechanism of twist insertion for core type friction spinning and open end friction spinning are different,which are described below.

Twist insertion in core-type friction spinning:
In core type friction spinning, core is made of a filament or a bundle of staple fibres is false twisted by the spinning drum. The sheath fibres are deposited on the false twisted core surface and are wrapped helically over the core with varying helix angles. It is believed that the false twist in the core gets removed once the yarn is emerged from the spinning drums, so that this yarn has virtually twist less core. However, it is quite possible for some amount of false twist to remain in the fact that the sheath entraps it during yarn formation in the spinning zone.

Twist insertion in Open end type friction spinning
In open end type friction spinning the fibres in the yarn are integrated as stacked cone. The fibres in the surface of the yarn found more compact and good packing density than the axial fibres in the yarn. The Figure 8 shown the arrangement of fibres in the DREF-3 yarn as stacked cone shape .

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  • Structure of the yarn tail:

The yarn tail can be considered as a loosely constructed conical mass of fibres, formed at the nip of the spinning drums. It is of very porous and lofty structure.The fibres rotating at very high speed. Lord and Rust have been studied a number of short-duration photographs of the yarn tail during the yarn formation. In these photographs, they located an appendage protruding from the open-end of the yarn tail and called it as the tip of the tail. Observing through the perforated drums, they found this tip to be very unstable, flickering about like a candle flame a draught. With the help of the photographs, they have concluded that the yarn tail is enlarged and torpedo-shaped being squashed by the nip of the perforated drums and the fibres on its surface are loosely wrapped. Moving away from the tip, these wrappings have been shown to
become tighter. They have further added that the surface structure of the tail consists of outstanding fibres, which stand out almost radically.

  • Spinning Tension for DREF yarns

Figure 9 explains that the Friction spun yarns have less spinning tension during the yarn formation. Due to less tension during the spinning the core component can be placed exactly at the centre of the yarn.

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  • Friction Spun Yarns Properties:

Friction spun yarns (DREF) yarns have bulky appearance (100-140% bulkier than the ring spun yarns).The twist is not uniform and found with loopy yarn surface. Friction spun yarns with high %age of core have high stiffness. Friction spun yarns are usually weak as compared to other yarns. The yarns possess only 60% of the tenacity of ring-spun yarns and about 90% of rotor spun-yarns. The increased twist and wrapping of the sheath over the core improve the cohesion between the core and sheath and within the sheath.

The breaking elongation ring, rotor and friction spun yarns have been found to be equal. Better relative tenacity efficiency is achieved during processing of cotton on rotor and friction spinning as compared to ring spinning system.

Depending on the type of fibre, the differences in strength of these yarns differ in magnitude. It has been reported that 100% polyester yarns, this strength deficiency is 32% whereas for 100% viscose yarns, it ranges from 0-25%. On the other hand, in polyester-cotton blend, DREF yarns perform better than their ring-spun counterparts. A 70/30% blend yarn has been demonstrated to be superior in strength by 25%. The breaking strength of ring yarns to be maximum followed by the rotor yarn and then 50/50 core-sheath DREF-3 yarn.

DREF yarns have been seen to be inferior in terms of unevenness, imperfections, strength variability and hairiness. DREF yarns occupy an intermediate position between ring-spun and rotor spun yarns as far as short hairs and total hairiness s concerned. For hairs longer than 3mm, the friction spun yarns are more hairy than the ring spun yarns. Rotor spun yarns show the least value in both the values. DREF yarns are most irregular in terms of twist and linear density while ring spun yarns are most even.

Chattopadhyay and Banerjee have studied the frictional behaviour of ring, rotor, friction spun yarns of 59 and 98.4 Tex spun from cotton, polyester, viscose fibres, with varying levels of twist. The yarn to yarn and yarn to guide roller friction was measured at different sliding speeds and tension ratios. However for polyester fibres, the rotor spun yarn showed highest friction, followed by friction and ring spun yarns.

  • Advantages of Friction spinning system

The forming yarn rotates at high speed compare to other rotating elements. It can spin yarn at very high twist insertion rates (ie.3,00,000 twist/min). The yarn tension is practically independent of speed and hence very high production rates (up to 300 m/min) can be attainable. The yarns are bulkier than rotor yarns.

The DREF II yarns are used in many applications. Blankets for the home application range, hotels and military uses etc. DREF fancy yarns used for the interior decoration, wall coverings, draperies and filler yarn. Core spun yarns thro this friction spinning are used in shoes, ropes and industrial cable manufacturing. Filler cartridge for liquid filtration also effectively made with these yarns. Secondary backing for tufted carpets can be produced with waste fibres in this spinning system .Upholstery, table cloths, wall coverings, curtains, hand-made carpets, bed coverings and other decorative fabrics can be produced economically by DREF Spinning system. Heavy flame-retardant fabrics, conveyor belts, clutches and brake linings, friction linings for automobile industry, packets and gaskets are some examples were the DREF yarns can be effectively used.

The DREF-3 yarns made fabrics used in many applications like backing fabrics for printing, belt inserts, electrical insulation, hoses, filter fabrics and felts made from mono-filaments core. Hot air filtration and wet filtration in food and sugar industries these yarns made fabrics are used. It also used in clutch lining and brake lining for automotive industries.he multi-component yarns manufactured using DREF 3000 technology are mainly employed for technical textiles of the highest quality. They provide heat and wear protection, excellent dimensional stability, outstanding suitability for dyeing and coating, wearer comfort, long service life , as well as a range of other qualitative and economic advantages. These include cost savings due to the use of less expensive materials, special fibres and wires as yarn cores. Apart from their strength, DREF 3000 yarns are also notable for their good abrasion-resistance,uniformity and excellent Uster values compare to previous systems.

  • Limitations of Friction spinning system

Low yarn strength and extremely poor fibre orientation made the friction spun yarns very weak.The extent of disorientation and buckling of fibres are predominant with longer and finer fibres.Friction spun yarns have higher snarling tendency. High air consumption of this system leads to high power consumption.  The twist variation from surface to core is quite high; this is another reason for the low yarn strength. It is difficult to hold spinning conditions as constant.  The spinning system is limited by drafting and fibre transportation speeds.

Website: http://drefcorp.com

Automatic bale openers or pluckers


Modern mills now a day’s uses automatic bale openers or feeders in place of conventional hopper bale openers for more accurate mixing/ blending and also helps to eliminate mane power.

Modern bale pluckers can be mainly classified into two categories viz.

1. Moving bale type

The first generation bale opening machines were mostly stationary. Only the bales were moved either backward or forward or in a circle. The examples of these types of machines are Trutzschler multi-bale plucker, karousel-beater type opener by Rieter, etc.

2. Moving beater type

The second generation machines are of the travelling type i.e. they move past the bales of the layout and extract material from top to bottom. Travelling machines have the advantages that more bales can be processed as an overall unit, and thus better long-term blend is achieved. It should be noted however that these machines extract material only in batches, i.e. they can process only one, two or maximum three bales simultaneously. If long term blend is needed to be achieved, then mixing machines must be included downstream from the bale opener. These machines are completely electrically controlled and extract material evenly from all bales evenly, independently of varying bale density.

In concept, these machines are most commonly utilized now a day. Machines similar to uni-floc by Rieter are developed by various other manufactures viz. Optimix by Hargeth Hollingsworth, B12 by marzoli and blendomat by Trutzschler. The latest uni-floc provided in modern Rieter blow room line in place of the hopper bale opener is UNI-FLOC A-11.

UNIFLOC A-11

· OPERATIONAL PRINCIPLE

The A 11 UNI-floc processes cotton from all sources and manmade fibres in staple lengths of up to 65 mm. The bales being opened are placed lengthwise or crosswise on both sides of the bale opener, and the take-off unit can process up to four different assortments.

Reduction of the raw material into micro-tufts is assured by the patented double teeth on the take-off roller and the grid with closely set clamping rails. The unique geometry of the double teeth ensures the uniform treatment of the entire bale surface. Retaining rollers travelling with the take-off unit prevent bale layers from sloughing and ensure precise, controlled operation over the entire height of the bale. The A 11 UNI-floc still produces small tufts, even at maximum output of 1400 kg/h.

The take-off unit is lowered by a preselected or computed distance at each pass. Running-in and running-out programs compensate for the differing hardness of the bales over their cross section and ensure a uniform level of production. The fan incorporated in the swivelling tower extracts the opened tufts and feeds them into the tuft channel running between the guide rails. Transport to the following machine is pneumatic.

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Figure 1 OPERATIONAL PRINCIPLE OF UNI-FLOC A-11

· DISTINGUISHING FEATURES OF UNI-FLOC A-11

The UNI-floc is basically one type of opening which is most commonly utilized in place of “hopper bale openers”. The distinguishing features of UNI-floc are:

1. Bale opening into micro-tufts for effective cleaning and dust extraction.

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Figure narrow grid gauge for micro-tufts

Micro tufts are the basic requirement for the production of yarn quality. Trash and dust can only be removed from natural fibres gently and efficiently on the surface of the tufts.

The take-off unit of the UNI-floc is considered to be the “heart” of the system as it is responsible for micro tuft formation. The patented take-off roller and the grid design with small gaps between the clamping rails enables small fibre tufts ( micro tufts ) to be extracted. The twin-tooth profile ensures uniform, gentle and efficient extraction of the tufts, also irrespective of the take-off roller’s direction of rotation.

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Figure comparison of output and tuft size in modern machine(UNI-floc A-11) to conventional bale opener

2. Uniform take-off of bale lay-down by means of “BALE PROFILEING”

Bale Profiling guarantees totally uniform bale take-off. The height profile of the bale lay-down is precisely detected by light barriers and memorized. Scanning is performed at a constant speed of 9 m/min. Tufts are already taken off in the profiling phase. Continuous feeding of the subsequent machines is thus ensured from the outset.

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Figure uniform take-off of bale lay-down by means of bale profiling

During the subsequent passes the bales are opened at the preselected speed of travel and take-off depth. In the process the system automatically compensates for differences in height in the bale profile. Labour-intensive manual levelling is eliminated. After the required height range, take-off depth and speed of travel have been entered for each group of bales, take-off proceeds fully automatically.

3. Simultaneous processing of up to 4 assortment

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We can lay down as many as 130 bales in four groups on each side of the machine. This means that four assortments can be processed automatically at the preselected take-off speed and with the required production volume.

4. Patented, individually interchangeable double teeth on the opening roller

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Figure Patented, individually interchangeable double teeth

The double teeth enable maintenance intervals to be halved. The teeth are mounted individually. They can easily and quickly be replaced if required, without removing the take-off roller. This explains the exceptionally high operational readiness of the A 11Uni-floc

5. Processing of cotton from all sources and man-made fibres in staple lengths of up to 65 mm

 

6. Output of up to 1 400 kg/h (carded sliver)

7. Bale lay-down over a length of 7.2 to 47.2 meters

A bale lay-down of overall lengths of 7.2 to 47.2 meters and two take-off of unit lengths of 1 700 mm and 2 300 mm. The maximum version is capable of accommodating raw material up to 40 000 kg. This ensures flexible, economical and largely autonomous processing on UNI-floc A-11.

8. Take-off width selectable between 1 700 mm and 2 300 mm

 

9. Graphic interface for easy, intuitive operation at the control panel

The control panel is placed facing the extraction duct, providing a clear view and safety for operating the machine. Setting and control of the A 11 UNI-floc can easily be performed at the screen.

10. Interface to higher-level control and information systems available

In the interests of optimum monitoring of the installation as a whole, this modern machine control unit can be connected to the UNI-control or UNI-command control system. UNI-control and NI command also provide the interface to Reiter’s higher-level SPIDER web mill monitoring system.

 

11. Maximum yield due to optimized processes

Digg This

Metallic Card Clothing


INTRODUCTION:

As Carding machine design improved in 1950’s and 60’s, it became apparent that card clothing was a limiting factor Much time and effort was spent in the development of metallic card clothing.

· There are two rules of carding

  1. The fibre must enter the carding machine, be efficiently carded and taken from it in as little time as possible
  2. The fibre must be under control from entry to exit

· Control of fibres in a carding machine is the responsibility of the card clothing

· Following are the five types of clothing’s used in a Carding machine

  1. Cylinder wire
  2. Doffer wire
  3. Flat tops
  4. Licker-in wire
  5. Stationary flats

CYLINDER WIRE:

The main parameters of CYLINDER Card clothing

  1. Tooth depth
  2. Carding angle
  3. Rib width
  4. Wire height
  5. Tooth pitch
  6. Tooth point dimensions
  1. Shallowness of tooth depth reduces fibre loading and holds the fibre on the cylinder in the ideal position under the carding action of the tops. The space a fibre needs within the cylinder wire depends upon
    its Micronaire/denier value and staple length.
  2. The recent cylinder wires have a profile called “NO SPACE FOR LOADING PROFILE”(NSL). With this new profile, the tooth depth is shallower than the standard one and the overall wire height is reduced to 2mm , which eliminates the free blade in the wire. This free blade is responsible for fibre loading.Once the fibre lodges between the free blade of two adjacent teeth it is difficult to remove it.In order to eliminate the free blade, the wire is made with a larger rib width
  1. Front angle not only affects the carding action but controls the lift of the fibre under the action of centrifugal force. The higher the cylinder speed , the lower the angle for a given fibre. Different fibres have different co-efficient of friction values which also determine the front angle of the wire.
  2. If the front angle is more, then it is insufficient to overcome the centrifugal lift of the fibre created by cylinder speed. Therefore the fibre control is lost, this will result in increasing flat waste and more neps in the sliver.
  3. If the front angle is less, then it will hold the fibres and create excessive recycling within the carding machine with resulting over carding and therefore increased fibre damage and nep generation.
  4. Lack of parallelisation, fibre damage, nep generation, more flat waste etc. etc., are all consequences of the wrong choice of front angle.
  1. Each fibre has a linear density determined by its diameter to length ratio. Fine fibres and long fibres necessitates more control during the carding process. This control is obtained by selecting the tooth pitch which gives the correct contact ratio of the number of teeth to fibre length.
  2. Exceptionally short fibres too require more control, in this case , it is not because of the stiffness but because it is more difficult to parallelise the fibres with an open tooth pitch giving a low contact ratio.
  • RIB THICKNESS:
  1. The rib thickness of the cylinder wire controls the carding “front” and thus the carding power. Generally the finer the fibre, the finer the rib width. The number of points across the carding machine is determined by the carding machine’s design, production rate and the fibre dimensions. General trend is towards finer rib thicknesses, especially for high and very low production machines.
  2. Rib thickness should be selected properly, if there are too many wire points across the machine for a given cylinder speed, production rate and fibre fineness, “BLOCKAGE” takes place with disastrous results
    from the point of view of carding quality. In such cases, either the cylinder speed has to be increased or most likely the production rate has to be reduced to improve the sliver quality
  • POINT POPULATION:
    The population of a wire is the product of the rib thickness and tooth pitch per unit area. The general rule higher populations for higher production rates, but it is not true always. It depends upon other factors
    like production rate, fineness, frictional properties etc.
  • TOOTH POINT:
    The tooth point is important from a fibre penetration point of view. It also affects the maintenance and consistency of performance. Most of the recent cylinder wires have the smallest land or cut-to-point.
    Sharp points penetrate the fibre more easily and thus reduce friction, which in turn reduces wear on the wire and extends wire life.
  • BLADE THICKNESS:
    Blade thickness affects the fibre penetration. The blade thickness is limited by practical considerations,but the finer the blade the better the penetration of fibres. Wires with thin blade thickness penetrate the more easily and thus reduce friction, which in turn reduces wear on the wire and extends wire life.
  • BACK ANGLE:
    A lower back angle reduces fibre loading, but a higher value of back angle assists fibre penetration. Between the two extremes is an angle which facilitates both the reduction in loading and assists fibre penetration and at the same time gives the tooth sufficient strength to do the job for which it was designed.
  • HARDNESS OF WIRE:
    The cylinder wire needs to be hard at the tip of the tooth where the carding action takes place.The hardness is graded from the hard tip to the soft rib. High carbon alloy steel is used to manufacture a cylinder wire and it is flame hardened. Rib should not be hardened, otherwise, it will lead to mounting problems.

The design or type of clothing, selected for the fibre to be carded is important,but it is fair to state that within reason, an incorrect design of clothing in perfect condition can give acceptable carding quality whereas a correct clothing design in poor condition will never give acceptable carding quality. There is no doubt that the condition of the clothing’s is the most important single factor affecting quality at high rates of production. Wire condition and selection of wire are considered to be the two most important factors which influence the performance of modern high production carding machines.

· The condition of the clothing may be defined as the collective ability of the individual teeth of the clothing to hold on to the fibre against the opposing carding force exerted by other teeth acting in the carding
direction. For a given design of clothing the condition of the teeth determines the maximum acceptable production rate that can be achieved at the card.

· The speed of the main cylinder of card provides the dynamic force required to work on separating the fibres fed to the card but it is the ability of the carding teeth on the cylinder to carry the fibre forward against the opposing force offered by the teeth of the tops which determines the performance of the card. Increasing cylinder speed increases the dynamic forces acting upon the carding teeth and thus the condition of teeth becomes more important with increased speed.If the condition and design of the cylinder wire is poor, the teeth will not be able to hold onto the fibre through the carding zone, thus allowing some of the freed fibre to roll itself into nep.

DOFFER WIRE:

  1. The doffer is a collector and it needs to have a sharp tooth to pickup the condensed mass of fibres circulating on the cylinder. It also requires sufficient space between the teeth to be efficient in fibre transfer from the cylinder, consistent in the transfer rate and capable of holding the fibre under control until the doffer’s stripping motion takes control.
  2. A standard doffer wire has an overall height of approx. 4.0 mm to facilitate the deeper tooth which must have sufficient capacity to collect all the fibre being transferred from the cylinder to meet production requirements. Heavier webs require a deeper doffer tooth with additional collecting capacity to handle the increased fibre mass.
  3. The doffer wire’s front angle plays a very important part in releasing the fibre from the cylinder wire’s influence. A smaller angle has a better chance of enabling the doffer wire’s teeth to find their way under
    the fibres and to secure the fibre’s release from the cylinder with greater efficiency. A 60 degree front angle for Doffer has been found to give the optimum performance under normal carding conditions. Too small an angle results in cloudy web and uneven sliver whilst too large an angle results in fibre recirculation and nep generation.
  4. Having collected the fibre, it is important for the doffer to retain it until it is stripped in a controlled manner by the doffer stripping motion. The tooth depth, tooth pitch and rib width combine to create the space available for fibre retention within the doffer wire. Thus they directly influence the collecting capacity. If the space is insufficient, fibre will fill the space and any surplus fibre will be rejected. When
    the surplus fibre is left to recirculate on the cylinder, cylinder loading can take place. Unacceptable nep levels and fibre damage will also result. In severe cases pilling of the fibre will take place.
  5. The point of the doffer wire normally has a small land which helps to strengthen the tooth. The extremely small land of around 0.05 mm ensures that the doffer wire height is consistent, has no adverse effect on fibre penetration and is considered essential for efficient fibre transfer from the cylinder. The land has microscopic striations which are created during manufacturing or grinding. The striations help to collect the fibres from the cylinder and keep them under control during the doffing process.
  6. It has been found that a cut-to-point doffer wire penetrates the fibre better than does the landed point wire but is less likely to keep the fibre under control during the doffing process. Sometimes a cut-to-point doffer wire is accompanied by striations along one side of the tooth for this reason. Until recently 0.9mm rib thickness is standardised for doffer wire, regardless of production and fibre characteristics.This rib thickness has been found to give optimum results. However doffer wires with a 0.8mm rib thickness have been introduced for applications involving finer fibres.
  7. In general 300 to 400 PPSI(points per square inch) has been found to perform extremely well under most conditions. Doffer wire point population is limited by the wire angle and tooth geometry. Higher
    population for doffer does not help in improving the fibre transfer.
  8. As the production rate rises, the doffer speed also increases. The doffer is also influenced by the centrifugal force, as is the cylinder.But cylinder wire front angle can become closer to counter the effect
    of centrifugal force, to close the front angle on a doffer wire would reduce its collecting capacity and result in a lowering of the production rate. The solution is to use the wire with striations, which will hold the fibre until the doffer is stripped.
  9. The hardness of the doffer wire is a degree lower than that of the cylinder but sufficiently hard to withstand the forces generated in doffing and the resultant wear of the wire. The reason for this slightly lower hardness requirement is the longer and slimmer tooth form of the differ wire.
  10. The fibres which are not able to enter the wire will lay on top, i.e.completely out of control. There fore instead of being carded by the tops the fibres will be rolled. Similarly a fibre buried too deep
    within the cylinder wire will load the cylinder with fibre, weaken the carding action and limit the quantity of new fibres the cylinder can accept. Therefore, the production rate would have to be reduced.

LICKER-IN WIRE:

  1. Licker-in with its comparatively small surface area and small number of carding teeth, suffers the hardest wear of all in opening the tangled mass of material fed to it.
  2. Successful action of the Licker-in depends upon a penetrating sharp point rather than a sharp leading edge as with the cylinder wire. Therefore the licker-in wire cannot be successfully restored to optimum performance by grinding.
  3. The most satisfactory system to adopt to ensure consistent performance is to replace the licker-in wire at regular intervals before sufficient wear has taken place to affect carding quality.
  4. The angles most widely used are 5 degrees negative or 10 degrees.
  5. There is no evidence to suggest recommendation of a tooth pitch outside the range of 3 to 6 points per inch.
  6. It is better to use Licker-in roller without groove. Interlocking wires are used for such type of licker-ins. This avoids producing the eight precise grooves and to maintain them throughout its life. Interlocking wire is almost unbreakable and thus no threat to the cylinder, tops and doffer in the event of foreign bodies entering the machine.

FLAT TOPS:

  1. The flat tops are an equal and opposite carding force to the cylinder wire and it should be sharp,
    well maintained and of the correct design.
  2. The selection of flexible tops is very much related to the choice of cylinder wire, which in turn is related
    to the cylinder speed, production rate and fibre charactersitics, as previously stated.
  3. The modern top is of the semi-rigid type, having flexible foundation and sectoral wire. The points are
    well backed-off and side-ground to give the necessary degree of fineness. The strength of the top from a carding
    point of view is in the foundation and is affected by the number of plies and the type of material used.
    The position of the bend in the wire is determined by stress factors, at around 2:1 ratio along the length of the wire protrusion.
  4. The modern top is made from hardened and tempered wire to increase wear resistance , thus improving
    the life of the flat top.

· Life of the cylinder wire depends upon

  1. Material being processed
  2. production rate
  3. cylinder speed
  4. settings

· Wear is the natural and unavoidable side effect of the work done by the vital leading edge of the metallic wire tooth in coping with the opposing forces needed to obtain the carding action which separates fibre from fibre. When the leading edge becomes rounded due to wear, there is a loss of carding power because the point condition has deteriorated to an extent where the leading edge can no longer hold on to the fibre against the carding resistance of the flats. This ultimately leads to fibres becoming rolled into nep with consequent degradation of carding quality. Therefore it is important to recognise that, due to the inevitable wear which takes place during carding, metallic wire must be reground at regular intervals with the object of correctly resharpening the leading edge of each tooth.

· GRINDING:

  1. GRINDING A CUT-TO-POINT CYLINDER WIRE:
    1. Wire points of cylinder have become finer and the tip is cut-to-point.Because of this new profile, it has become necessary to recommend a little or no grinding of the cylinder wire following mounting.
      TSG grinding machine of GRAF(wire manufacturer) can be used to sharpen these modern wires. TSG grinding is a safe method of grinding.
    2. Before grinding , the wire should be inspected with a portable microscope to ascertain the wear. Based on this and the wire point land width, no of traverse for TSG grinding should be decided. If the width of the wire point tip is bigger and the wear out is more, the number of traverse during grinding should be more. For a new wire, 3 or 4 traverses may be enough. But it may require 10 to 30 traverses for the last grinding before changing the wire, depending upon the maintenance of the wire.
  2. GRINDING A NORMAL CYLINDER AND DOFFER WIRE:
    1. The first grinding of the metallic wire on the cylinder and doffer is the final and most important step leading up to providing the card with a cylinder in the best possible condition for carding well at maximum production rate.Grinding the lands of the teeth provides the leading edge of each tooth with the final sharpness required for maximum carding power.
    2. The first grinding should be allowed to continue until at least 80% (for cylinder) and 100% (for doffer) of the lands of the teeth have been ground sufficient to sharpen the leading edge of the tooth.
    3. To ascertain this stage of grinding, it is necessary to stop the cylinder regularly and use a simple microscope to examine the teeth at random across and round the cylinder.
    4. If the wire on the cylinder is of good quality and has been correctly mounted, the initial grinding period should be completed with in 20 min.
    5. It is essential to avoid over-working the wire before taking corrective action. The regrinding cycle must be determined accurately for the conditions applying in the individual mill, by using the microscope.
    6. If regrinding is done properly, there are several advantages
      1. carding quality will remain consistent
      2. There is no risk of overworking the wire
      3. Time required for regrinding is very short
      4. The exact condition of the clothing is known
      5. The working life of the wire is likely to be longer because the points are never allowed to become worn
        beyond recovery
    7. To obtain acceptable grinding conditions at the low grinding speed, the grindstone must always be SHARP, CLEAN and CONCENTRIC. If the grinding stone is gradually allowed to become dull and glazed
      through constant use, the limited cutting action available will eventually disappear, resulting in burning and hooking of the carding teeth.
    8. Due to the low peripheral speed of the grindstone which has to be used, it is most important that the speed of the wire to be ground is as high as is practicable to provide a high relative speed between
      the grindstone surface and the cardig teeth.If wire speed is low, the individual carding tooth spends too long a time in passing under the grindstone, thereby increasing the risk of hooking and burning the tooth, which is usually irreparable.
    9. With cylinder grinding, speed is no problem because the normal operating speed of the cylinder is more than sufficient. The speed of the doffer for grinding is more commonly a problem and this should be driven at a minimum speed of 250 m/min, to avoid damage when grinding the wire, the design which is particularly susceptible to hooking due to the long fine, low angled teeth needed on the doffer.
    10. The directions of rotation for metallic wire grinding are normally arranged so that the back edge of the tooth is first to pass u nder the grindstone. This is termed grinding “back of point”
  3. GRINDING FLAT TOPS:
    1. Flat tops provide the opposing carding force against the cylinder wire and hence can equally effect
      carding quality.It is essential to ensure that the tops are kept in good condition to maintain maximum
      carding power with the cylinder.Again, the only reliable approach is to examine the tops with the
      microscope and decide whether grinding is required or not.
    2. For cards fitted with regrindable tops, it is good practice to regrind the flats at regular intervals
      thus ensuring that the conditions of the two principal carding surfaces are always complementary one to other.

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Industrial Revolution – Timeline of Textile Machinery


Several inventions in textile machinery occurred in a relatively short time period during the industrial revolution.

  • 1733 Flying shuttle invented by John Kay – an improvement to looms that enabled weavers to weave faster.
  • 1742 Cotton mills were first opened in England.
  • 1764 Spinning jenny invented by James Hargreaves – the first machine to improve upon the spinning wheel.
  • 1764 Water frame invented by Richard Arkwright – the first powered textile machine.
  • 1769Arkwright patented the water frame.
  • 1770Hargreaves patented the Spinning Jenny.
  • 1773The first all-cotton textiles were produced in factories.
  • 1779Crompton invented the spinning mule that allowed for greater control over the weaving process
  • 1785Cartwright patented the power loom. It was improved upon by William Horrocks, known for his invention of the variable speed batton in 1813.
  • 1787Cotton goods production had increased 10 fold since 1770.
  • 1789 Samuel Slater brought textile machinery design to the US.
  • 1790Arkwright built the first steam powered textile factory in Nottingham, England.
  • 1792Eli Whitney invented the cotton gin – a machine that automated the separation of cottonseed from the short-staple cotton fiber.
  • 1804 Joseph Marie Jacquard invented the Jacquard Loom that weaved complex designs. Jacquard invented a way of automatically controlling the warp and weft threads on a silk loom by recording patterns of holes in a string of cards*.
  • 1813 William Horrocks invented the variable speed batton (for an improved power loom).
  • 1856William Perkin invented the first synthetic dye.