textile science

Different stages of textile production

INTRODUCTION

Fabrication or fabric construction is a way of producing fabrics and each of the several or various fabric construction techniques used to produce leather fabrics creates a structure with distinctive aesthetic and structural features .Because these features affect the serviceability of the fabric as well as its installation and maintenance requirements, they influence the suitability of the fabric for various ends use applications.

Fabric is the material that is used to make clothing or household articles. The third successive stage in the making of a fabric is understanding the various methods of creating fabrics

Methods used for fabric formation

·         Weaving

·         Knitting

·         Bonding

·         Felting

·         Netting

·         Lamination

·         Macramé etc.

 

Weaving

It is the interlacing of two sets of yarns at right angles to each other. The lengthwise ones being warps or ends and the crosswise ones being wefts or picks or filling.

The edges where warp yarns are closely packed are referred to as selvedges

Weaving is an ancient accomplishment that dates as far back as 4,000 BC. In countries such as Egypt, Europe, Asia and South America. Where expertly woven samples of the basic weave were found. Weaving is the second stage of developing fibers into fabrics. Weaving probably became unknown before spinning. Primitive man may have observed interlaced grasses and twigs in the nest of birds and thus discovered how he could make clothing for himself with basket etc. or he may have seen bushes naturally interlaced as they grew. Spinning developed when man discovered that the raw materials could be improved before they were woven. In the course of time very simple looms were made and which were hand operated. The modern power loom used in textile industry today still contains essentially the same parts and performs the same operations as the simple hand operated loom.

Machine used for weaving is called a loom. There are simple looms e.g. tappets, cardboards, paper, straw, round, free form loom & complicated looms e.g. dobby and jacquard

Loom

The loom is the machine that produces woven textiles by interlacing warp and filling yarns at right angles to each other. The primitive weaving on a loom was a fairly simple procedure. The lengthwise yarns called the warp were separated and secured at each end of the loom to remain taught. A device called a reed which resembled a loom with long teeth was fixed at the weaving end to keep the warp yarns separated and was used to push each filling yarns into place.

The crosswise yarns called the fillings, picks or weft were wound around a stick woven over and under alternative yarns to form the interlacing and then pushed together with the reed to form a firm cloth. The early improvements in this procedure were the heddle (headle) and the shuttle. The heddle was a wooden bar device which could raise alternative yarns of the warp creating a triangular opening called the shed through which the filling could more easily be pasted. The shuttle an improvement of the ball of filling wrapped around a stick was a smooth bent shaped device powered at both ends which held a removable spindle wound with filling yarns. The shuttle could then be thrown through the shed. The heddle would be turned to reverse the position of the warp yarns and the process repeated. This procedure with the addition of the power automation, size and speed is still followed and is the basis of the textile industries capacity to supply fabrics of all types for billions of customers.

 

Simple tappet loom

It consist of the following

1)      Rollers

·         Has rollers on both ends on which warp threads are wound at one end and the cloth is wound on the other end

2)         Healed /heddles

·         This are wooden strips in a wooden frame through which the warp yarns are threaded in search a manner that the yarn goes through holes in the strips and spaces between the strips

·         The process of threading the warp yarns is called denting or drawing in

·         The heald is lowered and raised to create passages known as sheds for the weft yarns to be passed through during weaving

3)      Shuttle

·         A shuttle carries the weft yarns from one edge of the loom to the others

·         Weft yarn is wound on a prim which is placed on a shuttle

·         The machine is automatic such that when one prim is wound of the weft yarn the process of weaving doesn’t stop but the prim is removed and a new one is replaced automatically

4)      Reed

·         Resembles a metal grill

·         It pushes weft yarns to the felt of the cloth that is already formed after the yarns have been passed through the shades

·         When the shuttle shades one weft yarn through the shades it’s said to be a pick

·         The process of pushing the weft yarns upward by the reed is known as beating up

                   

Preparation for Weaving

In the weaving operation, the lengthwise yarns which form the basic structure of the fabric are called the warp and the crosswise yarns are called filling. Weft or proof. The fillings yarns undergo little strain in the weaving process. In preparing them for weaving it is necessary to only spin them to the desired size and give them the amount of trust required for the type of fabric for which they will be used. Warp yarns must go through some operations to prepare them to withstand the strain of weaving process. This operation does not improve the quality of yarns. The operation involved in preparing the warp yarns are;

1.      Spooling:

The yarn is wound on larger spools or cones which are placed on a rack called creel. From this rack the yarns are wound on a warp beam which is similar to a huge spool. An interrupted length of hundreds of warp yarns result all lying parallel to another.

2.       Wrapping:

Involves wrapping of yarns around a beam from packages of yarns to a creel/stand. 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

The No. of yarns in a warp depends on:

                                                                    i.            Yarn thickness (count)

                                                                  ii.            Fabric design

                                                                iii.            Fabric width

                                                                iv.            The structure of the fabrics

3.      Sizing/Slashing

Sizing involves application of adhesive to the warp before weaving. A lubricant and other substances may be added and the mixture is called size. The size may include starch, tallow (animal fat used for making wax) and paraffin wax and gelatin

The slasher machine covers every yarn with a starch coating to prevent breaking during the weaving process. The sized yarns are passed over large steam heated copper cylinders that remove the moisture and set the size.

They are then wound on the final warp beam and are ready for loom

4.      Drawing:

 The warp yarns are drawn through the heald eyes individually. The heald eyes connect the individual warp yarns to the shafts available for shedding. The distribution of the individual war yarns among the heald shafts depends on the weave chosen for the Fabric. Drawing is a time consuming process and difficult to be made automatic. Even today, it is mostly done manually.

5.      Denting:

After drawing though the heald eyes, the warp yarns have to be drawn through the dents in the reed as well. Denting controls whether a fabric will be woven as a dense One or a less dense light fabric.

                                      Action of weaving

In any type of weaving four steps are fundamental. However the preliminary step is threading warps through the eyes of the heddle. The four steps involved are:

1.      Shedding: - this is separating warps yarns or the shuttle to pass through by raising or lowering the harness. In the simplest weave construction, the heddle harness plane raises or lowers certain groups alternate warp yarns so that the fillings yarns alternate in passing under one loop of warp yarns and over another.

2.      Picking: - this is inserting the weft yarn or picks with a shuttle as the harness raise the heddle which in turn raises the warp yarns. The filling yarn is inserted through the shed by a small carrier device called a shuttle. A shuttle contains a bobbin of filling yarns which undergo through a hole in the side as the shuttle moves across the width. A single crossing of the shuttle from one side of the loom to the other is known as a pick.

3.      Battering: - is the pushing or beating of the weft or filling yarns firmly in place by means of the reel. All warp yarns pass through the heddle eyelets and through the openings in another frame that resembles a comb known as a reed. With each picking operation, reed pushes automatically or battens each weft yarn against the portion of the fabric that was already formed. This third weaving operation gives the fabric a firm compact construction and ensures uniform spacing of the filling yarns and good crosswise yarns in the fabric.

4.      Taking up and letting off – with each shedding, picking and battering operation the newly constructed fabric must be wound on the cloth beam. This process is known as taking up. At the same time, the warp yarns must be released from the warp beam, and is known as letting off.

 

GENERAL FEATURES FOUND IN WOVEN CLOTH OR FABRIC

1.      The selvedge – a self-edge. As the shuttle moves back and forth the width of the shed, it weaves a self-edge on each side of the fabric which is usually ¼” to 3/8” wider or even wider. The selvedge prevents the fabric from raveling (fraying).

It is usually made more compact during waving and stronger than the rest of the fabric. Done by using heavier warp yarns or by using stronger weave e.g. plain selvedges, constructed of as simple plain weave with the same size of yarn as the rest of the fabric but the threads are packed more closely together. This kind of selvedge is fairly durable and firm.

·         Tape selvedges – sometimes constructed with a plain weave but are often made of the blanket weave which makes it flatter weave, made of heavier yarns or ply yarns which provide greater strength.

·         Split selvedges – made by weaving a narrow width fabric twice its ordinary width with two selvedges in the centre. The fabric is then cut between the selvedges and the cut edges are furnished with a chain stitch or hem.

·         Fused selvedges – made of fabrics of thermoplastic fiber e.g. nylon by heating the edges of the fabric. The fiber melts and fuses together sealing the edges.

2.      Warp and weft threads – when making a garment one is able to distinguish the warp and the weft. The warp yarns take most of the strain and therefore they should move up and down in the garments and in household textiles. Patterns are always laid lengthwise on the fabric or along the warp and warp yarn run up and down along the selvedges.

Warp yarns are usually more compact and highly trusted than the weft. The wefts will run across the warp or across the selvedge. Warp yarns are stronger than the wefts, most fabrics stretch less in the warp deviation but will stretch more in the weft.

3.      Right side of the fabric – in most cases the R.S of the fabric is recognized, by Lustre, prints, figure weave patterns, twill ridges e.g. satin weaves has satin floats, pile, slub yarns.

4.      Closeness of weave and cloth count – the count of cloth which expresses the number of warps or ends per cm gives an indication of closeness or looseness of a weave e.g. cotton fabric with a count of 24x20, meaning 24 warps and 20 wefts per cm is more closely woven than a cotton fabric with a count of 11 by 9.

A closely woven fabric keeps its shape better, shrinks less, is less likely to slip at the seams and wears longer than loosely woven one of similar construction.

 

                          CLASSIFICATION OF WEAVES

·         The raising and lowering sequence of warp threads in various sequences gives rise to many possible weave structures such as

1.      Plain weave

2.      Satin /sateen weave

3.      Twill weave

1)      Plain weave

It’s the simplest way of interlacing the warp and wefts. It’s the most common type of fabric construction method, it results to the weft yarn going alternatively over and under one warp yarn. The frequent interchange of yarn results in a firm cloth

·         It’s  much used in cloth requiring hard wearing properties and lightness

     Sample structure of plain weave

 

                                                                                                                     1*1

           Characteristics of plain weave

i.        Both sides of the weave are identical i.e. there is no right or wrong side of the fabric unless printed or specially furnished.

ii.      The threads interlace on alternate order of one up and one down

iii.    The thread density is limited

iv.    It produces a relatively stronger fabric

v.      It’s the least expensive weave to produce

 

Advantages of plain weave

i.        It’s simplest and least expensive type

ii.      Produces a smooth and shiny surface fabrics resulting from passing the weft yarn over and under numerous warp yarns to create long floats

iii.    Higher productivity rate due to large working widths and a variety of fabrics construction

iv.    Durable

 

Disadvantages of plain weave

i.        May run if snugged

ii.      Curl edges may occur.

 

Uses of plain weave

·         Clothing outfits e.g. suits

·         Bed sheets

·         Home furnishings

·         Table cloths

·         Hats

 

Variations of plain weave

The following are variations of plain weave

                                                           i.            Rib weave

                                                         ii.            Matt /basket weave

                                                       iii.            Fancy weave

 

i)                  RIB WEAVE

·         They are of two types i.e. the warp rib and weft rib

·         The filling yarns (wefts) are larger in diameter than the warp yarns and vice versa

·         The fabric produced have raised ribs either horizontally, vertically down the fabric depending on whether the heavier, thicker yarn is used for the warp or the weft

                 Samples of rib structures

Regular warp rib

 

                                                                                                                       2/2

 

 

 

Irregular warp rib

                                                                                                                    3/2                                                         

                  Characteristics of warp ribs

·         Produces ribs or cords in the weft direction

·         Warp yarn is finer than weft yarn

·         Two or more weft yarns pass over or under a warp

·         Weft yarns are low twisted yarns

 

                                   Regular weft rib structure

     

                                    ½ (2+2) weft ribs

                       Irregular weft rib

                                  ½ (2+2) weft ribs

Characteristics of weft rib

·         Produces ribs or cords in the warp direction

·         Finer yarns are used as weft and coarser one as warp

·         Two or more yarn passes over or under a weft yarn

·         Normally two heald shafts are used

Advantages of Rib weave fabrics

·         Fabrics are resistant to tear and abrasion

·         It’s versatile hence comfortable to wear

·         It’s thin, smooth and has luster

·         Can have either warp or weft rib

Disadvantages of rib weave

·         Frays easily

·         Stretches on the bias

Uses of rib fabrics

·         Used to make broad cloth

·         Cord fabrics

·         Poplin fabrics

·         Taffeta fabrics

 

ii)                HOPSACK /MATT/BASKET WEAVE

·         Also referred to as ‘Panama weave’

·         It’s a plain weave with two or more yarns woven together in a checkered pattern resembling that of a woven basket

·         Two or more yarns are used in both the warp and filling direction

·         The group of yarns are then woven as one producing a basket

Sample structure

                                                                              

Characteristics of Basket weave

·         Uses double warp and weft yarns to produce design that resembles familiar pattern of a basket

·         Two or more yarns pass alternatively over and under two or more warp yarns

·         Two or more yarns with little or no twist are interlaced with corresponding number of warp yarns

·         They are woven in a pattern of  2*2, 3*3, and 4*4 instead of 1*1 which is the plain weave

             Advantages of Basket weave

·         Fabrics are decorative

·         Easy to construct

·         It’s flexible

Disadvantages of basket weave

·         It’s time consuming

·         Fabrics are not durable

           Uses of basket/matt weave

·         Used in coats

·         Used to make suits

·         Used to make hopsack

·         Used to make hats

 

2)       SATIN/SATEEN WEAVE

Typically has a glossy surface and a dull back. It’s characterized by four-nine or more fill (wefts yarns) floating over a warp yarn or four warp yarns floating over a single weft yarn

Satin is a warp faced re-arranged twill and sateen is a rearranged weft faced twill

              Sample structures

 

                                          Satin                                                                      4/1

 

                                  Sateen                                                                        1/4

 

         Characteristics of satin/Steen weave

·         They produce smooth and lustrous fabrics

·         The fabrics are not as strong as fabrics produced by other weaves

·         The fabrics are soft to touch

·         When subjected to rough surfaces, the fabric will easily tear

·         They are either warp or weft faced weaves

Advantages of Satin/Sateen

i.        It’s flexible

ii.      It’s lustrous with a smooth surface

iii.    It drapes an excellent manner

iv.    Short float fabrics are more durable than long float fabrics

v.      Good for styles

Uses of satin/sateen weave

·         Athletic shirts

·         Women’s lingerie

·         Night gown

·         Blouses

·         Evening gowns

·         Home furnishing

 

3)      TWILL WEAVE

It’s one of the main elementary weaves. It produces diagonal ridges across the surface of the fabric. The twill or diagonals may run from left to right as in most wool and worsted twills or from right to left as in most cotton twills.

The diagonals are always at a steep or slight angle. In the simplest twill the weft passes over two warp and over one alternately in each row following one yarn is skipped and then the weft proceeds as previously.

                  Classification of twill weave

Twill weave can be classified according to:

i)                    Stepping

·         Warp –way twill which is 3/1

·         Weft way twill whose structure is 3/2

 

ii)                  Direction of twill on the face of the fabrics

·         S-Twill or Left-hand twill weave

·         Z- Twill or Right –hand twill weave:3/2 Z

 

iii)                The face yarn (Warp or Weft)

·         Warp face twill weave whose structure is 4/2 S etc.

·         Weft face twill weaves which is constructed of 1/3

·         Double face twill weave which is 3/3 Z etc.

 

Sample structure

   2x2 twill

 

Left hand twill

               Characteristics of twill weave

i.        They form diagonal lines from one selvedge to another

ii.      Creases less

iii.    Do not soil but cleaning is more difficult

iv.    Softer and more flexible than plain weave

v.      More ends and picks per unit area than plain weave

vi.    More cloth thickness

vii.  Interesting surface and texture

vi.    More pliable

vii.  They are warmer

Examples of fabrics made from twill weave

·         Jeans/denim

·         Gabardine

·         Cotton drill

·         Khaki

·         Worsted fabrics

·         Tweed

·         Flannelette

·         Suiting materials especially wool and rayon

   Variations of twill weave

·         Herring bone

·         Chalon

·         Diamond

ASSIGNMENT

Read and make notes on fancy weaves

      Pile weave

      Leno/gauge

      Swivel

      Lappet

      Dobby

      Jacquard