Weaving is the most basic process in which two different sets of yarns or threads are interlaced with each other to form a fabric or cloth. One of these sets is called warp which is the lengthwise yarn running from the back to the front of the loom. The other set of crosswise yarns are the filling which are called the weft or the woof.

Preparing Warps and Wefts for Weaving

The warps form the basic structure of fabrics. As such, they are made to pass through many operations before actual weaving is done. These operations include spooling, warping and slashing. In spooling, the yarn is wound on larger spools, or cones, that are placed on a rack known as creel. From the creel, the yarns are wound on a warp beam, which looks like a huge spool. These lengths of hundreds of warped yarns lie parallel to one another. These yarns are unwound for slashing, or sizing. The yarn is coated with sizing with the help of slasher machine. Slashing prevents chafing or breaking of yarns during weaving process. Sizing is either starch based or a synthetic like polyvinyl alcohol or a water soluble acrylic polymers. The sized yarns are then wound on a final warp beam and are ready for the loom.

The filling yarns experience less strain during the weaving process. Their preparation includes spinning them to the required size and giving them just the right amount of twist desired for the kind of fabric they will be used.

Basic Weaving Operations

No matter what type of weaving is being done, four major operations are performed in sequence and are continuously repeated.

Shedding

In shedding, alternate warp yarns are raised to insert the filling yarn into the warp to form a shed. Shedding is automatically performed by the harness on the modern weaving looms. Harness is a rectangular frame to which a series of wires, called heddles, are attached. As each warp yarn comes from the warp beam, it passes through an opening in the heddle. The operation of drawing each warp yarn through its appropriate heddle eye is known as drawing in.

Picking

As the warp yarns are raised through shedding, the weft yarn is inserted through the shed by a carrier device. A single crossing of the filling from one side of the loom to the other is called a pick. Different methods are used for carrying the filling yarn through the shed in different kinds of looms. There are many types of looms including shuttle loom, shuttle-less loom, and circular loom.

 

Shuttle Loom

The shuttle loom is the oldest type of weaving loom which uses a shuttle which contains a bobbin of filling yarn that appears through a hole situated in the side. The shuttle is batted across the loom and during this process it leaves a trail of the filling at the rate of about 110 to 225 picks per minute (ppm). Although very effective and versatile, the shuttle looms are slow and noisy. Also the shuttle sometimes leads to abrasion on the warp yarns and at other times causes thread breaks. As a result the machine has to be stopped for tying the broken yarns.

Shuttle-less loom

Many kinds of shuttle less looms are used for weaving such as Projectile Looms; Rapier Looms; Water Jet Looms; and Air Jet Looms.

Projectile Loom

It is sometimes called missile loom as the picking action is done by a series of small bullet like projectiles which hold the weft yarn and carry it through the shed and then return empty. All the filling yarns are inserted from the same side of the loom. A special tucking device holds the ends of the wefts in place at the edge of the cloth to form the selvage. This loom needs smooth, uniform yarn which is properly sized in order to reduce friction. Projectile loom can produce up to 300 ppm and is less noisy then the shuttle loom.

Rapier Loom

Rapier loom comes in many types. Early models of it use one long rapier device that travels along the width of the loom to carry the weft from one side to the other. Another type of rapier loom has two rapiers, one on each side of the loom. They may be rigid, flexible or telescopic. One rapier feeds the weft halfway through the sheds of warp yarns to the arm on the other side, which reaches in and carries it across the rest of the way. Rapier looms are very efficient and their speed ranges from 200 to 260 ppm. These looms can manufacture a variety of fabrics ranging from muslin fabric to drapery fabrics and even upholstery fabrics.

Water Jet Loom

In water jet loom, a pre measured length of weft yarn is carried across the loom by a jet of water. These looms are very fast with speeds up to 600 ppm and very low noise. Also they don't place much tension on the filling yarn. As the pick is tension less, very high quality of warp yarns are needed for efficient operation. Also, only yarns that are not readily absorbent can be used to make fabrics on water jet looms such as filament yarn of acetate, nylon, polyester, and glass. However, it can produce very high quality fabrics having great appearance and feel.

Air Jet Looms

In the air jet weaving looms, a jet of air is used to propel the weft yarn through the shed at speeds of up to 600 ppm. Uniform weft yarns are needed to make fabrics on this loom. Also heavier yarns are suitable for air jet looms as the lighter fabrics are very difficult to control through shed. However, too heavy yarns also can't be carried across the loom by air jet. In spite of these limitations, air jet loom can produce a wide variety of fabrics.

Circular Looms

 These looms are particularly used for making tubular fabrics rather than flat fabrics. A shuttle device in it circulates the weft in a shed formed around the machine. A circular loom is primarily used for bagging material.

Beating Up

This weaving operation is also called battening. In it, all warp yarns pass through the heddle eyelets and through openings in another frame that looks like a comb and is known as reed. With each picking operation, the reed pushes or beats each weft yarn against the portion of the fabric that has already been formed. It results in a firm and compact fabric construction.

 

Taking Up and Letting Off

As the shedding, picking and battening processes are being operated, the new fabric is wound on the cloth beam. This is known as 'taking up'. At the same time, the warp yarns are released from the warp beam which is known as 'letting off'.

The pattern of the weave depends on the manner in which groups of warped yarns are raised by the harnesses to allow the insertion of the weft yarn. These differences are responsible for producing different types of fabric weaves. Weave patterns can create various degrees of durability in fabrics apart from their utility and looks.

 

Types of Fabric Weaves

Fabric weave is the pattern for manufacturing a fabric. The yarns are used in different ways to produce various effects or weaves. These weaves can be plain and simple, as well as artistic and decorative.

Plain weave is the most simple and common type of construction which is inexpensive to produce, durable, flat having tight surface on which printing and other finishes can be easily applied. The examples of plain weave fabrics are crepe, taffeta, organdy, cotton calicos, cheesecloth, gingham, percale, voile and muslin. 

Satin weave, although more complicated, is a flexible type of weave than the plain weave. It is called 'satin' when filament fibers such as silk or nylon are used and is called 'sateen' when short-staple yarns like cotton is used to make it. The satin weave is lustrous with a smooth surface and it drapes in an excellent manner. The examples of satin weave fabrics are bocade, brocatelle, crepe-satin, satin, peau de soie, velvet satin etc.

Twill weave is somewhat similar to plain weave. Twill weave is durable, heavier, wrinkle and soil resistant, and is more flexible than plain weave. The examples of twill weave fabrics are covert cloth, drill, jean, jersey, tussah, velvet, worsted cheviot etc.

Basket weave is a variation of plain weave in which the fabrics have a loose construction and a flat look. It is more flexible and stronger but less stable than a plain weave. This weave is used in composites industry, outerwear, monk's cloth and drapery fabrics etc.

Jacquard weave is for creating complex patterns on fabrics and is woven on jacquard loom. The fabrics made through this weave have floats, luster, and are more stable and stretchy than the basic weaves. Some of its examples are matelasse, satin Faconne etc. It is used for upholstery and drapery.

Rib weave is a basic weave which produces ribs on the fabric. Resulting fabric is abrasion and tear resistant, examples of which are broadcloth, cord fabric, faille, poplin, taffeta etc.

Dobby weave, a decorative weave results in small designs or geometric figures all over the woven fabric. It is done through dobby machines. This weave uses various yarns from very fine to coarse and fluffy yarns to produce a variety of fabrics. The standard dobby weave fabrics are flat and comparatively fine. Some examples are moss crepe, matelasse etc. Heavy dobby fabrics are used for home furnishings and for heavy apparel.

Leno weave fabric is transparently thin, durable, strong and permits passage of both light and air through it. Examples of fabrics with leno weave are gauze, net, tulle etc. The leno weave fabrics are used for light-weight membrane, laminating fabrics, making medium weight blankets etc.

Oxford weave fabrics are made with modified plain weave or basket weave and are generally used for apparels, particularly cotton shirting materials. The fabric is fine, soft and lightweight.

Cut pile is a carpet fabric in which the surface of the carpet is made of cut ends of pile yarn. It is durable depending upon the kind of fiber used, density of the tufts and the number of twists in the yarn. Examples of cut pile are cisele velvet, velour , saxony etc.

Uncut pile, also called loop pile or rounded loops, produces fabric without cutting the ends of yarns as opposed to cut pile. The resulting fabrics are very strong with which very strong carpets are made. They are also used for making towels. Examples are terry cloth, terry velour, moquette, etc.

Chenile fabric is usually a soft wool, silk, cotton, or rayon yarn with protruding pile having fur-like texture which resembles velvet. It is generally used for making sweaters, outerwear, upholstery, curtains, rugs, throws and blankets etc.