An Overview of Carding Cylinder

An Overview of Carding Cylinder

Bhavdip Paldiya
Dept. of Textile Technology
Sarvajanik College of Engineering & Technology, Surat, India
Cell: +91 9662020909
Email: bhavdipk9009@gmail.com

What is Cylinder:
The carding cylinder is usually manufactured from cast iron, but is now sometimes made of steel. Most cylinders have a diameter of 1280-1300 mm and rotate at speeds between 250 and 500 rpm.

Specification of Cylinder:

1. DIAMETER  : 50”(120 mm)
2. SPEED  : 250-500 rpm
3. WIRE POINT PER INCH: 550-650 
4. SURFACE SPEED: 1000ft/min.
5. TOTAL WIRE POINT: 30lac
6. WIRE POINT DIRECTION: Anti clock

Objectives of Cylinder:

1. Back plate:

• To hold the fibre.
• To prevent the development of undesirable air current.

2. Top feather edge sheet: It controls the wt. & thickness of the flat strips.

3. Cylinder stripping door: This door is used to strip the wire point of cylinder.

4. Bottom sheet:

• To hold the fibre.
• To prevent the development of undesirable air current.

5. Cylinder undercasing:

• Remove dust.
• To maintain constant airflow.

Types of Cylinder:
There are two types of cylinder.

1. Single cylinder
2. Double cylinder

1. Single cylinder carding machine:

Single cylinder carding machine

Specifications

• Cylinder Dia. 700mm
• Output: 100-250kgs/h
• Power: 18.5kw

Application

• This machine can open various baled fiber,and send to next procedure via fan.
• It opens fiber with pin plate,high production and good quality

A brief feature of single cylinder:

• Single Cylinder Carding Machine, up to 1.5 meters in diameter and up to 2.5 meters in width are produced as normal standard. 

• Cover all types of fiber from very fine to very coarse fiber deniers; fiber lengths up to 120 mm can be processed. Both synthetic and natural fibers of all types can be processed.

• Cylinders up to 1.5 meters in diameter and up to 2.5 meters in width are produced as normal standard. Carding machines outside this size range can be discussed dependent on ard main cylinders are balanced to a surface speed of 1500 meters / per min. 

• All types of carding machines both single and double doffers can be fitted with randomizer rollers or not dependent on customer’s needs. 

• Card wires can be supplied as surface wound or interlocking as required. 

• Card capacity is depending upon card type, fiber denier, types of fiber but can be excess of 800 kgs / per hour. 

• Other details and variables dependent on customer’s needs can be discussed with our technical staff. clients’ individual requirements.

2. Double cylinder carding machine:

Double cylinder carding machine

SPECIFICATION :

• ™ Middle cylinder diameter: Φ850mm,Φ635mm
• ™ Big cylinder diameter:Φ1230mm,Φ1020mm
• ™ Power:35KW

Application:

• Double doffer used for carding and mixing opened chemical fiber and blending material.

New type of double carding m/c

Specifications

• Product Name - double cylinder carding machine
• Working width: 1800mm 2000mm 2200mm 2500mm
• Capacity: 150kg/h 200kg/h 300kg/h
• Dia. of cylinder: 1230mm
• Speed: 20 - 50m/min

Application:

• Various kinds of fiber such as polyester,viscose,nylon,PP,fiberglas,etc

Cylinder Speed:

1. Higher cylinder speed helps fibre transfer. Higher the production, higher should be the cylinder speed.
2. Higher cylinder speed improves carding action, thereby imperfections are reduced

Cylinder Wire Selection:
Cylinder wire selection is very important, it depends upon cylinder speed, the raw material to be processed and the production rate.

The following characteristics of cylinder wire should be considered.

1. Wire angle
2. Tooth depth
3. Wire population
4. Rib thickness
5. Tooth profile
6. Tooth pitch
7. Tooth point
8. Overall wire height

Cylinder Wire Maintenance:

• For a modern cylinder wire of 2mm height, grinding with the normal grinding stone is not recommended. It is better to use TSG grinder to grind the wire every 2nd or 3rd month, so that the sharpness of the wire is always maintained. 

• TSG grinder does not grind the wire, therefore if the wire is worn out very badly the quality improvement using this grinding machine will be nil. Frequent grindings are recommended. If TSG grinder is not available, it is better not to grind 2mm wires. 

• The number of traverse should increase depending upon the life of the wire. The number of traverse for successive grindings should be like this 3, 5, 10, 17 etc. Anyway the best method is to confirm with the microscope. If the grinding is not sufficient, the number of traverse should be increased.

Cylinder Construction in Modern carding
The cylinders of modern carding machines are almost solely welded constructions (Fig. ). They consist of the shell reeled of metal sheet welded along its edges, bottoms with hubs stiffened with ribs, the shaft and the reinforcement rings. Such constructions are used by leading carding machine manufacturers, and particular solutions are different as to the side hubs construction and reinforcement rings

Cylinder Construction

Loads acting on the main cylinder of carding machine
The loads acting on the cylinder result from:

• The influence of fiFIBER on the teeth of card wire during the carding process; the forces are small and are omitted when calculating deflection of the cylinder shell, 

• The construction deadweight and the centrifugal force; their influence on the cylinder deflection may also be neglected due to small rotational speed of the cylinder (circa 100200rpm), 

• Reeling at tension of the metallic card wire.

Tension forces acting on the metallic card wire coils

Reeling at tension S and the reeling pitch t of the card wire on the cylinder with the radius R (Fig. 3) exerts pressure on the cylinder shell directed radially inward with the value of

• Radial pressure = pr
• Force =F
• Surface force =px

Setting between cylinder and doffer
If the setting between cylinder and doffer is very close, the wires will get polished and this will affect the fibre transfer. If the setting is too wide, the fiFIBER will not be transferred to doffer from the cylinder, hence cylinder will get loaded. While processing synthetic fiber cylinder loading will badly affect the yarn quality. Moreover, it is difficult to improve the wire condition if the loading is severe. The only solution would be to change the wire. Therefore enough care should be taken while processing synthetic fiber.

Setting between cylinder and doffer

The setting between cylinder and flat

• The most critical setting in a carding machine is between cylinder and flat tops. While processing cotton, it can be as close as 0.175 mm provided the mechanical accuracy of flat tops is good. 

• Closer the setting between cylinder and flats, better the yarn quality. Neps are directly affected by this setting. Of course, very close setting increase the flat waste. For processing cotton the setting can be 0.25, 0.2, 0.2, 0.2, 0.2mm. For synthetic fiber it can be 0.3, 0.25, 0.25, 0.25, 0.25mm. 

• The setting between cylinder and flats can be as close as possible.

The setting between cylinder and flat

Heal and Toe Arrangement
The top half of the cylinder is surrounded by a series of flats. The flats are also covered with wire teeth, the points of which oppose & are set close to the wire on the cylinder. The setting between flats & cylinder is arranged that there is a wide3r setting at the back or trailing edge on which cotton first reaches for being carded & closer setting at the leading edge where the cotton leaves the flat. This arrangement is generally termed as ‘Heal & Toe’ arrangement.

Heal & Toe’ arrangement

Importance: The object of this type arrangement is to effect a gradual opening & carding of the fibers at each flat.

Historical Perspective of Textiles

Textiles - A Historical Perspective
Umar-Bin-Hossen
Govt. College of Engineering and Textile Technology,
Serampore, West Bengal, India
Email: uhossen@gmail.com 

 

 

The earliest technologies primarily used human hands as the main tools. Thesewere supplemented by other ancillary tools as revealed by archaeological excavations, which yield artifacts made of stone, bone etc. Textiles are an important source of reference for the cultural studies because of their universality. Textiles have always draped the body, whether human/deities/animal, floor and furniture. Unlike stone, clay, metal etc. textiles were traditionally made from biodegradable materials.

Women spinning with a wheel in early century

Textiles are indispensable part of human civilization. Textiles serve the individual, the home and the country. We are all aware that the prime needs of man are food, clothing, shelter.

The word Textile comes from the Latin word ‘Textilis’ and the French word “Texere” pertaining to weaving or to woven-fabric.

It covers all the woven materials whether made of wool, cotton, silk, jute, rayon or other manmade fibres. The variety of materials is simply tremendous. Textiles are so much a part of our daily lives that it is not unusual that we take them for granted. The fabrics that clothe us can be considered a part of us, just as the air we breathe and the environment that surrounds us. In fact, textiles have created a stimulus for man’s indigenousness.

Today, cotton is an integral part of textiles. There are 23 different varieties of cotton. It was a piece of cotton stuck to a silver vase and some spindles discovered in excavations which revealed that the spinning and weaving of cotton was known to the Harrappans, nearly five million years ago.

References to weaving are found in the Vedic literature. Method of spinning, the “arious materials used etc. are also mentioned in these ancients scripts. The history of Textiles is told many times over in the epics, the Puranas, the Graeco- Roman sources of Indian history and the classical Tamil Sangam Literature. Various techniques of weaving, designing, needlework etc. have survived through the centuries. 

 
The foundations of the textile trade began as early as the second century Be. Kalyan, a port, is place in that time from where textiles were exponed. A variety of fabrics, including cotton brocade, is mentioned in Chinese literature as Indian products exponed to China.

Hoard of block printed and resist dyed fabrics, mainly of Gujrati origin, found in the tombs of Fostat, Egypt, are the proof oflarge scale Indian export of cotton textiles to the Egypt in earlier times. They were exported in the early medieval times. Some of these motifs were found similar to those mentioned in the Western Indian manuscripts in the 13th century. There are others, which have resemblance to the block printed fabrics, in Gujarat.

The silk fabric was a popular item of Indian exports to Indonesia · around the 13th century, where these were used as barter for spices. Towards the end of the 17th century, the B~itish East India Company had begun exports of Indian silks and various other cotton fabrics to other countries.

These included the famous fine Muslin cloth of Bengal, Bihar and Orissa. The trade in painted and printed cottons or chintz, a favourite in the European market at that time, was extensively practised between India, China, Java and the Philippines, long before the arrival of the Europeans.

Before the introduction of mechanised means of spinning in the early 19th century; all Indian cottons and silks were hand spun and hand woven, a highly popular fabric, called the khadi.

Textile Designing
Textile is the base element of garments and it can also be a spirit of a home or office as it can change the look of an interior layout. It combines the love of colour, painting and drawing with the hands on satisfaction of working with fibre and cloth to make patterns in painted and printed forms.

Chute Feeding or Aero Feed System in Carding

Chute Feeding or Aero Feed System in Carding

Bhavdip Paldiya
Dept. of Textile Technology
Sarvajanik College of Engineering & Technology, Surat, India
Cell: +91 9662020909
Email: bhavdipk9009@gmail.com

Chute Feed System:

Chute feed is a system of feeding small tufts of cotton fibres directly from blow room to a series of cards, arranged in a circuit through pneumatic pipe.

A condenser in the pneumatic pipe sucks the material from blow room and delivers it to the flock feeder through pneumatic pipe by way of the filling trunk.

Chute Feed System

Photo electric cell in the filling trunk regulates the supply of material from blow room. From here, the material is fed to the kirschner beater by way of two ridged roller and two feed rollers. Krischner beater open the cotton into desired size tufts.

A fan blows the tufts from the kirschner beater into horizontal c closed circuit loop situated above the cards. The return trunk has the duty of returning the surplus material(after the supply to last card) to the beater that also of uniting well opened material with supply of fresh material thus delivering it directly to the horizontal duct again.

The separating head arranged in the horizontal closed circuit loop divert the part of tufts from air current into vertical feed chutes above the card inlets. Vertical feed chute ensures a uniform supply of material over the full working width of the card. Uniform separation of the tufts from the air current is achieved by adjusting the nose in the separating head. Raising the leading edge produces more separation and vice versa.

The weight of the card feed per meter depends on the static excess pressure in the installation. This drops practically linear from separator to separator by about 2mm head of water. The weight of the feed per unit length must be adjusted in accordance with this drop by increasing or deducting the distance between the glass front and the rear wall of the feed chute. The weight per meter ranges between 600 to 700 gms.

Thus while deviation of the card sliver count from one card to another must be regulated with the glass plate. The specific count of the sliver itself must be adjusted with the count change wheel.

Card Feed Chute: 

The feed weight at the card depends on the static pressure in the aerofeed system and the chute depth adjusted. Since the pressure diminishes from one feed chute to another, the chute depth must be matched accordingly. It can be varied from 80 mm to 120 mm and is read off on the scale at the arrow mark.

THEORY AND LITERATURE
The blow room machinery is linked to the cards by trunking and the opened cleaned cotton is conveyed by pneumatic means to each card – this the principle of chute feed system.

The basic elements of chute feed system are :

• Conveyor system to carry material from B/R to group of cards with the help of air.
• Proper control of air pressure in the conveyor system for smooth flow of material.
• A mechanism to feed the material at uniform weight per unit length and width.
• A delivery system to feed the material to the card feed roller.
• A sensing mechanism at chute to keep a certain amount of material as reserve and also to control the feed of material to the chute.

Present Development :
Automation – bale to cone : continuous automated spinning (CAS) in Japan

• Platts chute feed system type 685 
• Exact feed FBR chute feed system by trutzschler, germany
• ML snowflaker chute feed by U.S.A
• NSE chute feed system of bombay
• Vibra chute DS by W,.Germany
• Rando level feed by U.S.A
• Transautomal by Italy
• Aerodome by Switzerland

Views of Indian Mills :
The only reservation that seem to have is that its introduction in the processing line may result in high yarn count variations. This should not be so since C.F system has gained good acceptance in all the textile mills in advanced countries.

Lap Feed Demerits:

• Stoppage due to lap changes.
• Extra labour for lap trasportation
• Compression of fibres in the lap poses problem during opening in carding.
• More wastes due to lap tails and damages.
• Irregularity of sliver weight due to improper unwinding of laps.

Chute Feed Merits:

• Direct automatic feed to card increases B/R working efficiency.
• Elimination of Man power during scutcher operation.
• Processing of rejected lap is avoided.
• Due to loose form of feeding of fibres trash particles can be removed easily during carding.
• Suitable for synthetic fibres of bulky in nature, avoiding

Advantages of flock feeding or chute feed system :

• The automatic continuous feed directly linked to the blow room eliminates the lap formation. This increases the working efficiency of the blow room. 

• The main power requirement in doffing the lap, weighing, transportation to card and feeding at the card is eliminated. 

• The processing of rejected laps in the blow room is avoided. 

• The fibres are fed to the card in loose sheet form as against compressed form so that trash particles can be easily extracted from fibres by the carding action. 

• Excessive sliver irregularities due to the lap licking during high humidity, double lap feeding, lap splitting, lap piecing etc, are eliminated. 

• When compared to lap fed, there is a reduction of 1 % CV flock feeding card sliver. 

• Crushing of foreign materials seed bits and other trash particles during calendering and difficulty of removing a subsequent processes is reduced.

Disadvantages or limitations of chute feed system :

• Blow room should run the same number of hours per week as the cards do. 

• The card production must be kept excessive to assure continuous feed to drawframe at the time of stoppages at blow room due to maintenance and other unavoidable problems.

• Chute feed system control short term variation but not the medium and long term variations. 

• A reliable check on the nominal count can be established in lap forming system by controlling total lap weight and C.V. value of the weight per unit length. There is no such control in the chute feeding system. 

• Change of mixing will result in more waste in chute feed. 

 

Neps in Carding: Major Defect of Yarn Manufacturing

Neps in Carding

Bhavdip Paldiya
Dept. of Textile Technology
Sarvajanik College of Engineering & Technology, Surat, India
Cell: +91 9662020909
Email: bhavdipk9009@gmail.com

Textile terms and definitions define a `Nep’ as a small knot of entangled fibres that usually comprises dead or immature fibres.

Neps in cotton continue to be a major problem in the cotton yarn manufacturing process. The two main factors affecting nep formation are fibre characteristics and mechanical processing. The mechanical processes affecting nep formation include ginning, opening and blending, carding, combing, drawing and spinning.

Neps are associated with poor yarn and ultimately with poor fabric appearance and have an effect on yarn uniformity and dyeing quality.

Neps in the raw material can be classified as mechanical neps or biological neps. Mechanical neps are those made up of only fibrous material containing at least five or more fibres.

Neps containing foreign material such as seed coat fragments, leaf or stem materials were designated as biological neps.

A third category of neps found on the surface of the dyed fabrics was named pancake type neps. This type of nep appears as light or white spots in the finished fabric.

Ginning conditions that influence nep formation are the ginning process itself, the amount of lint cleaning, heat history and the amount of energy input into the individual fibre. In one study , it was found that ginning using three tower driers and two lint cleaners significantly increased the amount of card web neps compared with one lint cleaner and without using heat for drying.

It was also observed that with finer cottons, increasing the card licker-in speed increased the card web neps.

A closer flat-cylinder setting, on the other hand, reduced the web neps. It was also found a good correlation exists between the card web neps and the yarn neps.

Figure shows the neps in the card sliver over neps in the raw material.

Hence trials are to be concluded based on critical nep size reduction. The number of neps above critical nep size shall be eliminated in carding by optimising setting, grinding frequency, wire condition/replacement, suction, process parameters, etc.

It is to be noted that neps below critical nep size will not influence yarn quality/fabric appearance significantly. This analysis and controlling/minimising of critical nep size is highly significant for yarn dyeing quality requirements.

It is also advisable that any trials/R&D study should be concluded based on knitted fabric appearance/critical nep size in carding to impress/delight yarn buyers by manufacturing premium yarn quality.

General Discussion on Fabric Structure and Analysis Part-3

 ….Previous Part

Explain Briefly the Major Constructional Differences Between Pointed and Herringbone Twill Weave:

Pointed Twill Weave: 

It is the simplest and one of the most important modifications of twill weave produced by reversing the direction of twill at suitable interval A point is sellected (usually the last warp is sellected) as the reversing point and so it is sometime call as point twill. In this twill pointed or straight draft is used. This twill is produced by combining S and Z twist. According to reversing of direction there are two type of zigzag twill:

1. Horizontal zigzag twill.
2. Vertical zigzag twill.

1. Horizontal pointed twill: 

When the reversal direction of twill line occur upon the warp yarn,it result a horizontal zigzag twill,Here the basic twill is extended in warp direction.Here the number of warp yarn in a repeat is double of the number of weft.In horizontal zigzag twill pointed draft is used.

Horizontal pointed twill

2. Vertical pointed twill: 

When the reversal direction of twill line occur upon the weft yarn,it result a vertical zigzag twill,Here the basic twill is extended in weft direction.Here the number of weft yarn in a repeat is double of the number of warp.In Vertical zigzag twill straight draft is used. 

Vertical pointed twill

Hearing Bone Twill: 

This twill are constracted in a different manner from the ordinary zigzag twill.Though it also depend on reversal of twill direction Here reversal direction occurs after a middle line.Here at first the basic twill is drown then the number of central point is selected in zigzag twill.Rather in exdended second half of basic twill the following matter happened.

• The floating point of first half become down in second half.
• The down of first half become floating in second half.

In hearing bone twill straight draft is used.There are two type of hearing bone design

1. Horizontal hearing bone twill.
2. Vertical hearing bone twill.

Horizontal hearing bone twill: 

When hearing bone twill is created by extending the basic twill in warp direction,horizontal hearing bone result.

Horizontal hearing bone twill

Vertical hearing bone twill: 

When hearing bone twill is created by extending the basic twill in weft direction,horizontal hearing bone result.

Vertical hearing bone twill

Explain Fully the Various Reasons for the Construction of Twill Weave:

Twill weave are extensively used in manufacturing cloth for garments household cloth and industrial cloth.

1. Generally dimond,diaper and zigzag twill are used for making pillow,cover,screen,unpholstery,bed sheet,towel etc.
2. Continious twill are used for making fabric for shirting,suiting and pantin(denim,gaverdine).
3. For making various type of ornamental cloth,other derivatives of twill weave are used.
4. Hearing bone twill are used in the cloth of suiting and overcoats.

References

1. Textile design & Colors (Seventh Edition) by Watson & Gronski.
2. Woven Cloth Construction; by Robinson & Mark.
3. The American Cotton Handbook volume 2 by Dames S. Hamby.
4. An Overview of Twill Weave by Md. Rubel Miah Department of Textile engineering World University of Bangladesh. (http://textilelearner.blogspot.com/2013/07/different-types-of-twill-weave.html)

 

 1  2  3

General Discussion on Fabric Structure and Analysis Part-2

…..Previous Part                                                Next part…..

WEFT RIBS

This is plain weaves in which two or more ends weaves together as one. To form weft rib the thick picks always pass over or under two or more thick or fine ends. Here the plain weave is extended for two ends as illustrated for 2-2 filling rib & a 3-1-1-3 filling rib below;

Figure 4: Weft Rib

Weft rib is the amplification in width of plain weave. If the number of lifted or lowered yarns in each shed opening is identical, weft rib is designated as regular; in the opposite case, it is designated as irregular.

Regular weft rib weave:
The number of yarns lifting or lowering in the even shed does not exceed 4. Therefore, there exist only 3 regular weft ribs: the weft ribs 2-2, 3-3 and 4-4.

Regular weft rib weave

Irregular weft rib weave:
As for the warp rib, there are three types of irregular weft ribs:

• The varied weft rib
• The interrupted weft rib
• The varied-interrupted weft rib

Irregular weft rib weave

Complementary weaves:
This structure, with its characteristically intricate patterns, has been used primarily for decorative borders—both on flatweaves and on the skirts of knotted-pile objects. It is not actually an ‘end finish,’ however. In a complementary-weft weave, weft yarns of contrasting colors are used in pairs, and each weft complements the action of the other exactly. If a light weft passes over four warps and under two, its dark-colored companion follows, passing under four warps and over two. The sequences are changed to vary the patterns: some wefts might go over and under 3 warps, or they might go over 5 and under 1, but they are always used in complementary pairs. All wefts are allowed enough ease to cover the warps completely, making this a weft-faced weave. When only two colors are used, the back and front faces are similar. The interlacement pattern is the same on both; the position of the colors is merely switched. Small X’s, for example, may be light on one face and dark on the other. Typical patterns are very small: little triangles, diamonds and rosettes predominate. The blocky Qashqa’i so-called ‘domino’ border features one of the more complex motifs. Warps of two different colours are set up in two complementary sets that are integral to the structure of the fabric. Unlike supplementary weft, there is no ground cloth on top of which the pattern is created. Each warp has its counterpart on the opposite face of the cloth, and the design is achieved from the two sets of warps interlacing with the weft. The result is a design with the colours in reverse on each face.

Complementary weave

Explain the Various Methods of Designation of Twill Weave and Give Reasons for the Construction of This:

Twill weaves are constructed upon any given number of threads exceeding two. The interlacing order of threads in the repeat in twills weaves is identical & the diagonal line is formed by advancing this order in step of one in either direction.

Twill weaves can thus be designated by describing the interlacing of the first threads; using the following methods;

1. 2 up; 2 down
2. 2-& -2
3. 2./.2

The third method , however , is the more convenient method .The above methods of designations indicates that on the first two pick the first two picks the first two ends are up & the following two down or that the first end is raised for the first two picks & lowered for the following two.

Thus for irregular twills the designation might be;

1. 1 up; 3 down; 2 up ; 2 down
2. 1-& -3 ; 2-& - 2
3. 1.2./.3.2

There are basically two reasons for twill construction;

1. They are used for ornamentation purposes.
2. They are constructed for enabling cloth of greater weight; closer settings & better draping quality.

Twill weave are extensively used in manufacturing cloth for garments household cloth and industrial cloth.

1. Generally dimond,diaper and zigzag twill are used for making pillow,cover,screen,unpholstery,bed sheet,towel etc.
2. Continious twill are used for making fabric for shirting,suiting and pantin (denim, gaverdine).
3. For making various type of ornamental cloth,other derivatives of twill weave are used.
4. Hearing bone twill are used in the cloth of suiting and overcoats.

  1  2  3

General Discussion on Fabric Structure and Analysis Part-1

General Discussion on Fabric Structure and Analysis

Bilal Yakubu
Dept. of Textile Science and Technology
Ahmadu Bello University, Zaria, Nigeria
Email: billsurf.net@gmail.com

Next Part….

WARP RIBS
Ribs & Cords are plain weaves structures in which considerable difference exist between the warp & the weft threads as regards to thickness, & number of threads per unit space. The term cord is frequently applied to a rib that runs the length of the cloth. These designs are found in unbalanced structures such as canvases & tarpaulin.

This is a plain weave in which two or more picks are inserted in the same shade .To form warp rib the thick ends always passes over or under two or more , thick or fine pick as shown in figure 1 below & of 2-2 warp rib . Here the plain weave is extended for two picks. It is possible, however to have a 3-1-1-3 warp rib as shown in 2 below;

Fig 1: Warp rib

Fig 2: Warp rib

Warp rib weaves are made by running two or more picks together, a shown in Figure-3 This produces pronounced weft-way ribs, the surface of which consists of warp threads. The rib effect is emphasized by the use of a greater number of ends than picks and the insertion of coarser weft yarns. Consequently, the picks tend to lie rather straight with the ends bending round them, thus producing a warp rib structure in which the warp is mainly visible. The advantage of introducing two free weft yarns instead of one coarse yarn is that a broad rib is achieved without greatly increasing the thickness or weight of the cloth.

Since some confusion can arise in the terminology used, it is worthwhile drawing attention particularly to the fact that ‘warp rib’ weaves produce ribs running weft-way.

Rib effects result from extending the plain weave vertically. The weft is thicker causing the warp to bend and form a warp surface rib running from selvedge to selvedge.

• Warp ribs are woven with a high warp sett, in which the ends cover the weft almost entirely.
• The ribs can be emphasized even more strongly by use of alternate slack and tight ends and thick and fine picks.

Fig 3: Warp Rib Weaves

If the number of inserted picks in each shed opening is identical, warp rib will be designated as regular; in the opposite case, it is designated as irregular warp rib.

Regular warp rib weave:
The numbers of inserted picks in an even shed opening do not exceed 4. Thereby, only three regular warp ribs exist: warp rib 2-2, warp rib 3-3 and warp rib 4-4.

Regular warp rib weave

Irregular warp rib weave:
The irregular warp rib can be classified in three ways:

1. The varied warp rib where the number of picks in each shed opening varies periodically.
2. The interrupted warp rib, where grooves are separated by one, two or several picks to only one fine weft.
3. The varied interrupted warp rib that is the combination of the two preceding cases 

Irregular warp rib weave

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