Explain weaving operations in fabric productions or types of weaving operations?

textile Designing
  1. Basic Weaving Operation:
  2. Basic Loom Operations:
  3. Selvedges:
  4. Thread Count:
  5. Basic Weave Structures:
  6. Surface figured weaves:

Basic Weaving Operation:

The machine used for weaving fabrics is a loom. Before weaving yarns intended forwarp must pass through such operations as spooling, wraping and slashing to preparethem to withstand the strain of weaving process. These processes do not improve qualityof yarns.

a. Spooling:

Yarn is wound on large spools, or cones which are placed on a rack called a creel from this yarns are wound on warp beam, which is similar to huge spool.

b. Starching:

These yarns are unwound to be put through a slashing or sizing bath. The slasher machine covers every yarn with a coating to prevent breaking during weaving process.

c. Wrapping:

The sized yarns are then wound on a final warp beam and are ready for the loom.The warp beam prepared now is then mounted on looms. Before the invention of conventional loom, back strap loom was in existence. Later on, the conventional loom replaced the back strap loom which is now-a-days not in use. The above given preparatory procedures were not followed in the back strap loom since the fabric was prepared manually.

On conventional loom, the warp beam is mounted at the back and warp yarns are conveyed to a cylinder called cloth roll, which is at the front of the loom and on which fabric is rolled as it is constructed. The warp beam holds the length-wise yarns and is located at the back of the loom.

This beam is controlled so that it releases yarn to the loom as it is needed.The Heddles are wires or metal strips with an eye located in the center through which the warp ends are threaded. The harness is the frame that holds the Heddles in position. Each loom has atleast two harnessess.

A majority of looms for regular fabrics have four to twelve harnessess and some looms may have as many as thirty-two. Harnessess can be raised or lowered to produce the shed through which the filling yarn is passed and thus controls the pattern of weave.The shuttle move back and forth in the shed created, passing the filling yarns between the warp yarns. The reed is a comb like device that helps to pack the filling yarns into position in the woven fabric.

Basic Loom Operation:

a. Shedding:

It is raising and lowering of warp yarns by the harnessess to make an opening for the weft yarns to pass through.

b. Picking:

It is the actual process of placing the weft yarns in the shed. This is done using a device known as ‘shuttle’. It has a metal strip in which bobbin or pin is inserted.

c. Beating:

Sometimes called beating in or beating up, consists of evenly packing the filling yarns into position in the fabric. It gives a compact construction to the fabric.

d. Taking up and letting off:

It involves taking up the newly manufactured fabric onto the cloth beam and letting off or releasing yarn from the warp beam. The operation maintains uniform distance and tension from warp beam to harness to completed cloth. Weaving is a major method of fabric construction. The technique probably became known before spinning.

Spinning developed when people discovered that the raw material could be improved before they were woven. In the course of time, rude looms were made, which were simple and hand-operated, fabrics produced on such looms are also known as hand loom fabrics where every thing is done by hands. The modern power loom used in the textile industry today essentially performs the same operation as the simple hand operated loom.

The fabric produced on power looms is made comparitively faster and has few defects in comparison to hand looms. Based on the picking operations looms are divided into various categories. The two major ones are based upon the method of filling insertion. Looms that uses shuttle are called conventional shuttle or fly shuttle looms. Shuttle looms have very compact selvedge. It is the oldest and versatile method of weaving so most different kinds of fabrics can be obtained. Very large wooden shuttle is used and every time it passes through warp yarns it causes abrasion and the productivity may go down because of the low strength of yarns.

The broken yarns show fabric defects. Shuttle looms are very noisy and PPM (Picks Per Minute—How many wefts laid in one minute) is 110 to 225. On the other hand looms that uses other devices to bring the filling yarn through the shed are called shuttleless looms. The source of the yarn for shuttleless looms are cones placed at the sides of the loom. Shuttle-less looms gives very high productivity at the same time they are less noisy when compared to shuttle-looms. They also have high productivity and fewer fabric faults. There are different types of looms other than conventional looms such as:

1. Single Projectile on Missile Loom

2. Multiple Projectile System

3. Rapier Loom

4. Jet Looms

Selvedges:

A selvedge is defined as length-wise edge of the fabric. Found on both ends of the fabric usually ¼ to ½ inches broad. Main purpose of selvedge is to hold warps and wefts together. It prevents fabric from ravelling. In machine loom a separate operation is required to finish the edges. Selvedge is usually much more compact than rest of the fabric. There are more warp yarns in the area of selvedge.

1. Mostly ply is used for selvedge.

2. Twist is more in selvedge.

3.Suppose body fabric is in a weak weave then the selvedge is stronger than the rest of the fabric.

4.Selvedge will depend on end use of fabric secondly on economy of production.

Thread Count :

Thread count or fabric count is determined by counting the number of warp (Ends) and wefts (picks) per square inch of fabric. Higher the thread count more compact will the fabric be; so it will be more strong and durable. A fabric with high thread count will be more costly. It is denoted by X × Y, eg., 50 ×30. Compact fabric shrinks less. Based on thread count there exists balanced and unbalanced constructions. When number of warp yarns are equal or nearly equal to the number of weft yarns, the construction is balanced and when the difference between the number of warp and weft yarns will be very large than that construction will be an unbalanced construction.

Basic Weave Structures:

There are three basic weaves. They are plain weave, twill weave and satin weave. All other weaves are a variation or a combination of these weaves. Basket weave and Rib weave are two variations of plain weave. In the same manner twill weave can also have number of variations, e.g., warp faced twill, weft faced twill, even twill, uneven twill, pointed twill, herring bone twill, gabardine, corkscrew and so on.

Graph paper (or pointed paper) is used to show the weaves or the order in which the yarns interlace in a fabric. It is used by textile designers to portray their designs or to analyse fabric weaves. Each vertical row of squares represents a warp yarn and each horizontal row of squares represents a filling yarn. A warp yarn crossing over a fillings usually shown by marking in the square called a ‘raiser’. A blank square over the warp called ‘sinker’.

The weave diagram does not show the number of yarns per inch between warp and filling. The yarn size and type are also not indicated. The completed design shows the interlacing from the face side of the cloth. Most weaves are analysed from the face side.

a. Plain weave:

A plain weave is a weave where each filling passes alternately over and under each warp in a square pattern. The interlacing is opposite in neighbouring cells. The repeat is over two ends and two picks.

b. Satin weave:

A satin weave is a weave where four (or more) shaft with warp floats in interrupted diagonal. Interlacings are never adjacent to one another. Satin repeat over altest 5 ends and 5 picks but the warp ends interlace only once per repeat.

c. Twill weave:

A weave characterized by diagonal lines on the face of the fabric. The weft or warp yarns interlace with more than one warp yarn but never more than 4 warp yarns. On each successive line weft moves the design one step to the right or the left forming the diagonal. Whatever the direction of the diagonal on the face of the fabric the direction is opposite on reverse. The diagonal can vary from a low 14° angle called reclining twill to a 75° angle called a step twill. The most common is 45° and is regular or medium twill,steeper the twill stronger the fabric is likely to be. A 2 x 1 twill weave will be one where warp will go over 2 warp and under 1 weft. Suppose you have 4/2 weave, then it means that you will have 4 +2 =6 harnesses, (i.e) the repeat will have 6 boxes horizontaly and 6 boxes vertically.

Surface figured weaves:

Many decorative and patterned fabrics can be made by inserting extra warp and/or filling yarns during the fabric construction process. When extra warp yarns are used, they are wound on to an additional warp beam and threaded into separate heddles so that they can be controlled-depending on the complexity of the pattern, either by the dobby or the Jacquard attachment. Looms used for such constructions must have numerous harnesses or individual yarn control, in order to have sufficient warp control for the design to be formed.

Controls for such fabrics permit great design flexibility, the use of several colors in the filling direction as well as the warp which may be strung with several different colors of yarn etc and the use of various types of yarns provides methods for producingfigure weaves in selected or spot areas of a fabric. The main types of fabric made through the use of additional yarns are lappet, swivel and spot.

a. Lappet weave:

Lappet is a fabric in which figure is achieved by introducing extra warp threads into a base fabric that is normally plain.

b. Swivel weave:

A fabric in which figure is achieved by the introduction of additional weft threads into a base fabric to produce spot effects.

c. Spot weave:

Spot designs can be made with either warp or extra filling yarns. The yarns are inserted the entire length or width of the fabric in predetermined areas.

d. Leno weave:

The leno weave may be called the doup weave or the gauze weave.

e. Pile weave:

The word pile comes from the Latin word for hair or fur. To obtain the hairlike or furlike surface, woven pile fabrics are made with three sets of yarns-a regular set of warp yarns (called warp ground yarns), a regular set of filling yarns (called filling ground yarns) and an extra set of either warp or filling yarns to form the pile surface (called pile yarns).

f. Double-cloth weave:

Double weaves are those in which atleast two sets of filling yarns and two sets of warp yarns are interlaced so that the interlacing moves between the sets at various points.

g. Dobby weave:

Dobby weave is a patterned weave used to construct designs that cannot be produced by the plain, twill or satin weaves. Dobby fabrics have small figures, such as dots, Geometric designs and small floral patterns, woven into the fabric. These decorative weaves are made with small patterns that repeat frequently.

h. Jacquard attachment:

Jacquard fabrics, frequently called Jacquard weaves, are large figured designs that depend on considerable flexibility in the control of the warp yarns to form sheds for placing filling yarns in the fabric.

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