102 woven fabric structure design and product planning

102. Woven Fabric Structure Design and Product Planning Số trang: 167 trang Ngôn ngữ: English --------------------------------------- Woven Fabric Structure Design and Product Planning discusses with the structural details of the woven fabric which has glimpses of primary, secondary, and tertiary weaves. The book has a number of examples on each topic, and a few chapters have been given with objective type of questions. The book is written with a view to link fabric formation and fabric structure. Any weave description invariably links the reader to weaving arrangements and thus, it is necessary for a reader to have a thorough knowledge of various loom aspects. The special feature of this book is that it provides a chance for the reader to complete the designs in the text book itself. Table of Contents • Dedication • Preface • Introduction to fabric structure • Classification of weaves and study of plain weave • Twill weaves and their modification • Sateen and satin weaves • Colour-and-weave effects • Huck-a-back weaves • Mock leno and distorted effects • Crepe surface and crepe weaves (Oatmeal) • Bedford cords and piques • Ornamentation of fabrics • Index

Planning

Woven Fabric Structure Design and Product Planning

J Hayavadana

New Delhi, India

Taylor & Francis Group

6000 Broken Sound Parkway NW, Suite 300

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© 2015 by Woodhead Publishing India Pvt Ltd.

Exclusive worldwide distribution by CRC Press an imprint of Taylor & Francis Group, an Informa business

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Version Date: 20150518

International Standard Book Number-13: 978-93-80308-97-5 (eBook - PDF)

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Dedication v

1.4.1 Group I: Classification with respect to

1.4.2 Group II: Classification with respect to weave 11

1.5.5 Expression of weight 13

1.5.7 Threads/unit area (reed  pick) and cover 15

1.6.1 Method of notation of structure or design 17

1.7.1 Selection of reed and its importance 20

1.9 Design or interlacement fashion (discussion is

1.9.1 Draft or drawing plan or drawing in draft 21

1.9.3 Type of relation among elements of fabric

1.10 Construction of elements of fabric structure 23

1.10.2 Notation for draft calculation of number

of heald shafts and methods of draft indication 231.10.3 Construction of design from draft and peg plan 241.10.4 Construction of peg plan from design and draft

1.10.5 Construction of draft from design and peg plan 26

1.13.5 Combined draft 31

1.15 Illustrative example for calculations in weaving 34

Multiple choice questions; select the correct answer: 36Write answers to the following in 2 or 3 sentences: 38Essay type questions; write answers to the following: 38

2.4.2 Modification of plain in warp way – warp rib

2.4.5 Commercial significance of ribs production 472.4.6 Production of weft rib or moreen

[Figs 2.2(a)–(d′)] 48

2.5.1 Modification of matt: fancy matt and stitched

2.8.1 Basis of classification of plain cloths 53

2.8.1.2 Based on weight 54

2.9.1.3 Cotton cloth for electrical insulation 55

2.9.1.6 Cotton typewriter ribbon fabric 56

2.9.1.9 Filament nylon blouse and

2.9.1.10 Filament nylon overall fabric 57

2.9.5.3 Cotton-mohair lining fabric 61

3.4.2 Construction of right hand (z) and

3.4.3 Stage-by-stage construction of twills 65

3.4.6.1 Rearranged twills on sateen base 68

3.5.1 Twist-twill interaction (emphasizing a twill) 783.5.2 Commercial twills [Figs 3.18(a)–(e)] 80

3.5.2.1 Three-end twills 80

5.2.1 Development of coloured stripe for

5.2.2 Development of patterns with compound

colouring 935.2.4 Development of dogstooth and houndstooth 94

I Choose the correct answer from the alternatives given: 96

6.2 Characteristics of huck-a-back toweling fabrics

6.3 Systematic construction of huck-a-back weave 100

6.3.1 Point paper representation [Figs 6.1(a)–(j)] 1016.3.2 Modification of ordinary huck-a-back 101

6.3.3.1 Beaming, counts of yarns and type

6.6.4.2 Ends leaded HC [Figs 6.2(d)

7.3 Construction of design for perforated fabrics

7.4 How exactly the openness is produced

(weaving|arrangement) [Figs 7.1(d) and (e)] 114

Answer the following questions in not more than six sentences 117

8 Crepe surface and crepe weaves (Oatmeal) 119

8.3 By reversing small tufts (principle of turn down) 121

8.5 By combining a plain weave with a floating weave 122

9.3.1 Simple or plain-faced bedford cords

9.5.1 wadding ends and their arrangement

9.8 Types of threads and their arrangement (RTP) 133

9.9.1 Simple or plain pique(single face or ground

9.9.4 How exactly the wadding picks are made

to lie at centre [Figs 9.2(e) and (e′)] 136

Index 145

I feel elated in dedicating the first edition of book titled “Woven Fabric Structure and Production Planning” to my family, friends, world and Textile Fraternity Indeed, Woven Cloth Construction and Design is a very interesting subject for any reader and also gives insight about method of fabric production Normally, a student feels that woven cloth construction is very tough subject But in reality, the subject is very simple, interesting and stimulating

After teaching the subject since the past two and half decades, a challenge was always stedfast in my mind about writing a book on WCC with a simple approach; and finally I decided to dedicate my book to my Textile Fraternity Initially it was very hard for me to prepare all the designs separately on paper and then subsequently transfer to a printable base as I found certain designs are very difficult for representation

This book has made an attempt to discuss the simple or single layered structures only and I have provided the work sheets and incomplete designs for reader or students for further practice, which is not the case generally

An attempt is also made to describe the loom equipment and construction particulars in respective cases

Any suggestions in improving the quality and content of the book in any corner is most welcome and can be intimated to me so as to improve the readability and accessibility Lastly, I feel that the book shall fulfill the requirements of reader and will satisfy his/her demands I thank M/S Woodhead Publishing India in bringing out the first edition

Lastly I thank Mrs G M Sridevi, freelance designer, New Nallkunta, Hyderabad, for her continued patronage support in getting the text typed without any mistakes

Prof Dr J Hayavadana

Fabric structure and design is a part of weaving which deals with production

of fabric on an equipment called loom Fabric structure deals with the construction of fabric (material data and manufacturing data) based on the specific end use To understand fabric structure, it is necessary to consider certain aspects related to weaving or fabric formation Weaving is a process

in which the cloth or fabric is produced on loom Each loom is specified in terms of reed space expressed in inches or centimetres and is related to width

of fabric to be produced or under consideration In other words, particular loom equipment is selected based on the nature of fabric to be produced with respect to width, category, nature, type of warp and weft, etc

The properties of the fabric depend on the fabric structure which is determined

by the following parameters: the weave, the density of threads in the fabric, the characteristics of warp and weft threads, the characteristics of fibres and the factors introduced during weaving, such as yarn crimp The particular order of interlacing of warp and weft threads forms the weave There are different methods

of interlacing which give infinite variety of weaves Two kinds of warp and weft intersections can be found in the woven fabric, depending on the mutual position

of warp and weft threads at the point of intersection, i.e warp over weft or weft over warp Different combinations of these two kinds of intersections can form short or long floats of warp and weft threads, and can form different weaves Among the parameters of fabric structure the weave is the most important one When all the parameters are constant except the weave, the influence of weave

on the fabric properties can be found The weaves with long floats of the threads produce looser structures and those with short floats, firm structure Due to this the properties of woven fabrics are changed, depending on the kind of weave

Fabric is defined as a structure characterized by length, width, thickness and weight, and is the interlacement of warp and weft Fabric comprises longitudinal threads known as warp (individual threads are called as ends) and horizontal threads known as weft (individual threads are called as picks) Warp is delivered from weavers beam and passes through drop wise, healds (heald eyes), reeds and finally culminates at fell Similarly, the weft is supplied from a package known as pirn, accommodated in a moving boat called shuttle and the later traverses from one side of the loom to other side The number of

Introduction to fabric structure

threads is expressed per unit area like per inch or per cm and is represented by

n1  n2 (ends and picks per cm or inch)

Whenever the shuttle traverses from one side to other side, it lays a pick or single weft Lifting of warp over the weft or lowering of warp under the weft forms interlacement or fabric

The warp threads are drawn through heald eyes of heald shaft (which are selected based on the total number of ends, drawing order, i.e number of ends drawn per each heald eye), through dents of reed (which may be pitch baulk or all metal type and generally two ends are drawn per dent) and finally converges to fell It is the heald shafts which may be lifted as per the order (lifting or peg plan) over a pick (which is inserted by shuttle as it passes through shed which in turn formed by separation of warp into layers) to form

a specific interlacement or design This is how a fabric is formed on loom During weaving rate of delivery warp is being controlled by let-off motion and fabric formed is wound onto cloth roller by take-up motion and it is to be noted that both will be working in unison

Fabrics differ on various grounds like count of warp and weft, nature of yarns, type of yarns, weaving method or order of interlacement, width, type

of selvedge required, etc To know the details of weaving motion, the reader

is suggested to refer any weaving book1

Each is characterized by different properties like physical, mechanical, comfort, functional, etc However, one could understand that these properties are manifested by the nature of yarns (single or double), twisted (soft or low or medium or high), type and nature of fibre (e.g cotton, wool, silk and circular, trilobal, serrated, etc.), type of yarn manufacture like cotton system or woolen system or worsted system

1.1 The process of fabric formation

Woven fabric is formed by interlacing two mutually perpendicular set of yarns, warp and weft (individually the threads are known as ends and picks) The simplest interlacing pattern is on two ends and two picks which is a plain weave A fabric is formed when warp is prepared from either sectional or beam warping depending on the type of yarn like single or double and respective pirn preparation or weft winding based on the type of pirn employed For a beginner it is necessary to know the details of the basic weaving process prior

to understanding of fabric structure

All loom motions are classified into primary, secondary and tertiary motions based on the sequence and importance in fabric formation (or essential and optional) In turn the primary motions are of three types which are set to occur

in a loom at a specific period of loom working For example in conventional crank loom, the motions are set according to crank timing and in modern

looms like shuttleless the timings are as per index wheel By setting these situations or timings one can witness the motion in loom The three motions

of primary are defined as follows

The first three operations are closely combined to follow each other at the proper time

Shedding: Division of warp into two or more layers for the purpose of

passage of shuttle carrying weft

Picking: Insertion of pick by a shuttle carrying weft or insertion of weft through

media like gripper or rapier or air jet or water jet (as found in modern looms)

Beating-up: Beating the newly inserted weft, known as a pick, into the

already woven fabric to a point known as fabric fell

The secondary motions include in regulating the warp from the back beam and winding of the fabric formed onto the fabric roller

Warp letting-off: Delivering the warp to the formation zone at the required

rate and at a suitable constant tension by unwinding it from the weaver’s beam

Cloth take up: Moving fabric from the formation zone at the constant rate

that ensures the required pick spacing, and winding the fabric onto a cloth roller.Schematically, a warp passes over sensitive or oscillating back rest, through drop wire (open type), through the heald eyes of heald shaft, through dents of the reed and onto the cloth roller

1.2 Important parts of loom

A loom has number of parts, each contributing to the proper function of the loom The material of construction, its placement and setting play significant role in satisfactory loom operation In the following paragraphs an attempt is made to list the parts of the loom

1.2.1 Heald shafts

This part is related to the shedding mechanism The heald shaft is made of wood or metal such as aluminum It carries a number of heald wires through which the ends of the warp sheet pass The heald shafts are also known as

‘heald frames’ or ‘heald staves’ The number of heald shafts depends on the warp repeat of the weave It is decided by the drafting plan of a weave The main function of the heald shaft is as follows:

• It helps in shed formation

• It is useful in identifying broken warp threads

• It maintains the order or sequence of the warp threads

• It determines the order of lifting or lowering the required number of healds for a pick In other words it helps in forming the design or pattern in a fabric.

• It determines the warp thread density in a fabric, i.e the numbers of heald wires per inch determine the warp thread density per inch

1.2.2 Sley or lay

It is made of wood and consists of the sley race or race board, reed cap and metal swords carried at either ends The sley mechanism swings to and fro It

is responsible for pushing the last pick of weft to the fell of the cloth by means

of the beat up motion The sley moves faster when moving towards the fell of the cloth and moves slower when moving backwards This unequal movement

is known as ‘eccentricity of the sley’ It is needed in order to perform the beat

up and also to give sufficient time for passage of shuttle to pass through the warp shed The beat up of the lastly laid pick of weft is accomplished through

a metal reed attached to the sley

1.2.3 Shuttle

It is basically a weft carrier and helps in interlacement of the weft with the warp threads to form cloth The shuttle which is made of wood passes from one end of the loom to the other It travels along the wooden sley race and passes between the top and bottom layers of the warp sheet The shuttle enters

a shuttle box fitted at either ends of the loom, after passing through the warp shed.Shuttle weight varies depending on the type of weaving and loom

1.3.1 Reed

It is a metallic comb that is fixed to the sley with a reed cap The reed is made of a number of wires and the gap between wires is known as dent Each

dent can accommodate one, two or more warp ends The count of the reed

is decided by the number of dents in 2 in The reed performs a number of functions which are enumerated as follows:

• It pushes the lastly laid pick of weft to the cloth fell

• It helps to maintain the position of the warp threads

• It acts as a guide to the shuttle which passes from one end of the loom

to the other

• It determines the fineness of the cloth in conjunction with the healds

• It determines the openness or closeness of the fabric There are various types of reed such as ordinary reed, gauze reed, expanding reed, V reed, etc

It is also known as the front rest It is placed above the cloth roller at the front

of the loom and acts as a guide for the cloth being wound onto the cloth roller The front rest together with the back rest helps to keep the warp yarn and cloth

in horizontal position and also maintain proper tension to facilitate weaving

1.3.5 Cloth beam

It is also known as the cloth roller The woven cloth is wound onto this roller This roller is placed below the front rest

1.3.6 Passage of warp through loom

The schematic diagram of the loom is illustrated in Figure 1.1, where the principal parts of the five basic motions are shown The warp after leaving the weaver’s beam 1 passes over two bars 2 and 3 connected by a bracket at each end One half of the warp end now passes under the back lease rod 4, and the

other half passes over this rod Those warp ends which pass under the back lease rod pass over the front lease rod 5, and ends from over the back lease rod pass under the front lease rod Therefore, the warp is completely divided as

it passes through the lease rods, and facilitates the straightening of any warp ends which may break and become entangled before they reach the healds 6 and 7 The lease rods also assist in forming an even shed Leaving the lease rods, the warp ends next pass through the healds Odd numbered pass through the front heald 7, and the even numbered ends pass through the back heald 6 The healds consist of heald wires with eyes at the centre through which the warp ends are passed, the warp ends being thus controlled in their upward and downward movements The warp ends next pass through the reed 8, this being comprised of a flat wire comb with the teeth secured at both ends Usually two ends pass between one tooth and the next—this space being termed ‘dent’ In the figure, two warp ends are represented as being in the same dent Point 9 is known as ‘Cloth fell’ It may be considered as the point where the warp and weft become cloth, because it is at this point where the last pick of weft, which was left by the shuttle, is beaten up by reed Fabric ends then pass through temples 10 The cloth passes over the breast beam/front rest 11, partly round the sand or emery roller 12, over the steel roller, or nip roller 13, and then onto the cloth roller 14

Figure 1.1 Passage of warp through loom Parts of the figure: 1: Warp

from weavers beam; 2 and 3: Pair of back rest; 4 and 5: Pair of lease rods; 6 and 7: Pair of heald shafts; 8: Reed; 9: Sley race or race board; 10: Temples

at cloth fell; 11: Breast beam or front rest; 12: Emery roller; 13: Nip roller;

14: Cloth roller

Table 1.1 Details of Fig 1.1

Part No Title Remark (Type, place of fitting, type of

material, method of control)

beam

These may be with beam ruffle of diameter ‘r’ with ordinary flanges as found on plain power looms or hand looms where these are used

on sectional warping machine or with special ends on the beam ruffle (with gear teeth) used for automatic looms or unconventional looms Wound with specific set length varies from 50 m for handlooms to above 5000 m for modern looms It lets off warp at a uniform rate as controlled by let off (which may be –ve or +ve or semi +ve) and has sturdy beam flanges and beam ruffle made of hindalium or aluminum Normally seen at the back of loom and D max It runs at slow speed and nearing D0 it runs fast The number of such beams may be two or three based on the RS of loom

Oscillating

type

Important member to regulate the warp tension based on the wrap angle as the beam weaves down As the name indicates it rests

at back side of loom and allows the warp over

it and thus measures the tension of the warp Three types are found, namely, stationary type (made of mild steel, found on non- or semi-automatic looms and not preferred) or oscillating type (made of mild steel) found on semi-automatic type looms with warp easing motion operated from crank shaft or sensitive back rest (made of SS or chromium coated SS) found on all modern automatic looms and shuttles looms with a pair or three rollers Back rests are placed in-between beam and lease rods and straight above the weavers beam Back rest not only regulates the warp tension during weaving, it also plays in improving fabric cover (position of the back rest)

4 and 5 Lease rods Made of SS (modern looms and automatic

looms) or aluminum (semi-automatic looms)

or wood (hand or pedal looms) are used to separate the warp sheets to facilitate shedding with equal shed depth While gaiting the rods are inserted when the lease bands inserted during post-sizing operations or sectional warping are replaced Lease rods are in-between heald shafts and back rest

6 and 7 Heald shafts These are made up of aluminum and have a

number of heald eyes each carrying a warp end and thus from shed for insertion of pick

by shuttle The healds are operated by a pair

of tappets from the bottom shaft or from a set of tappets or cams from a separate dobby

as found in modern looms In the automatic looms and hand looms these are framed structures carrying the small rods which accommodate heald eyes (inserted) But today in modern looms the healds are connected at bottom only to a positive shedding device which stays at the side of the loom Generally for plain weave two healds are tied as one (skip draft) is staggered

semi-as the back heald and is away from the fell

as compared to front heald In all the cases except in old type of Air Jet loom (Maxbo 100

cm RS heald shafts are inclined at an angle

to the horizontal), heald shafts are operated orthogonally to the horizontal Healds are arranged in-between lease rods and reed Number of HS used depends on the design woven and a maximum of 10–20 heald shafts are found Today selvedges are controlled by separate heald shafts

to the fell of the cloth Texture of the cloth depends on the type of reed used and pick spacing depends on the beat up force Reed has a unique motion known as ‘Eccentric

Motion’ (fast forward and slow backward) Conventional looms have crank operated sley and modern cam-operated sley Reed is made

of mild steel wires or metal wires spaced with 60% air space and are specified by reed count (stockport system) Modern looms have dwell

of 250 for reed In some cases (also due to different denting order used), fabric is found with what are known as ‘Reed marks’ and these serve as a method of indication of warp

in non-selvedge areas

all the cases true fell is found except in terry weaving a false fell is observed It is necessary

at this point beat up force should be equal to weaving resistance offered by fell Generally,

at fell the width of the cloth is equal to width

in reed and in some cases like reed bumping,

it is necessary to take care in avoiding the movement of fell towards reed as it causes shuttle trap

temples

Temples are made up of different types of materials based on the type of temple and preferred based on the type of the material woven Main function of temple is to control fabric shrinkage by holding it at ends such that width of warp in reed is equal to width of fabric at fell Loom temples can be positioned

by adjusting the temple brackets If care is not taken, a defect known as ‘Temple mark’

is found

made of SS roller Normally, FR is covered with a leather or fabric piece to prevent soiling of the cloth during normal working Conventional old looms use fixed front rest which is not recommended as the pick spacing

in fabric depends on the tension of the fabric following weaving

12 Emery roller Covered with strips of emery fillet (based on

the count of warp and weft) grips the fabric and assists in guiding the fabric to the cloth roller via nip roller Diameter of this roller depends on the type of take up motion and constant ‘Dividend’ does depend on the diameter of this roller It is driven by the last wheel in the train of wheels of take up motion

13 Nip roller Made of mild steel assists in guiding the cloth

onto cloth roller Normally stationary type and nearly 10–20 mm in diameter is housed below the front rest

may be frictionally driven with emery or separately driven by clutch assembly Cloth rollers are fixed to cloth wind up control devices as found on the conventional looms However, in modern looms, these are placed

on jumbo and sometime the cloth is inspected

by online process using Cyclops Diameter of cloth on these rollers may indicate the length

of fabric rolled from 100 m (in hand loom)

or 300 m (in automatic loom) or 300–400 m (in automatic loom) where it is controlled by clutch or several thousand meters as found today on unconventional looms depending on the type of loom and weaving practiced

1.4 General features of fabric

In any fabric the arrangement of threads either in construction or interlacement can be any one of the following:

• Warp-faced fabric (irreversible)

• Weft-faced fabric (irreversible)

• Equi-faced fabric (reversible)

1.4.1 Group I: Classification with respect to threads per unit area

Warp-faced fabric: Ends per unit area will be exceeding picks per unit area

and majority of the fabrics come under this category

Weft-faced fabric: Picks per unit area will be exceeding that of ends per

unit area and few fabric sorts are produced with this condition However, one should note that this is normally referred in weaving (specially with respect

to take up motion) as bumping condition, which also serves as a method to improve fabric cover In other words, pick wheel is greater than reed count Normally, we can hear some sound as the reed beats the fell of the fabric One sort of plain like casement is the best example

Equi-faced fabric: In this class both ends per unit area and picks per unit

area are equal This does not mean that reed used in weaving is equal to pick wheel (even though if an attempt is made with equal values of reed and pick, ends per unit space and picks per unit space will not be equal due to condition

of warp and weft in loom) However, this is achieved only by trial and error approach by selecting reed and pick But some of the fabric constructions call for this condition

1.4.2 Group II: Classification with respect to weave

Warp-faced weave: Number of warp up will be more than weft up (m > n, in m/n) Some of the modifications of the primary weave like plain and twill do

include this feature and are referred as unbalanced weaves However, during weaving they are woven as face down concept to reduce the warp tension Here, fabric face and back will be easily identified For example, 3/1 twill, 2/1 warp rib, A twill on 2/1, 3/2, 4/2 Here, it can be noted that popular twill like jeans or denim is warp faced in nature (2/1)

Weft-faced weave: Number of weft up will be more than warp up (m < n, in m/n) Some of the modifications of the primary weave like plain and twill do

include this feature and are referred as unbalanced weaves Here, fabric face and back will be easily identified For example, 1/3 twill, 1/2 warp rib, A twill

on 2/4, 3/5

Equi-faced weave: Majority of the weaves fall under this class Examples

are 2/2 rib or cord, 1/1 plain, 3/3 twill, etc In this type of fabric, face and back

of the fabric are same

1.5 Elements of fabric

Each fabric is characterized by the following:

(a) Body and selvedge

(b) Face and back

(c) Warp and weft

(d) Width and weight (GSM)

(e) Weave (warp-faced/weft-faced/equi-faced)

(f) Threads/unit area–cover factor Figure 3 shows selvedge

1.5.1 Body vs selvedge

Selvedge is the end point for a fabric and between the selvedges the fabric width is specified The selvedge is characterized by

(a) Width, which may be from 0.5 to 1.5 each side

(b) Weave, normally weave used in selvedge will be different from that of body

(c) Type of yarn, selvedge uses always double yarns and is drawn 2% per heald eye in heald shaft and 4% in reed

(d) Additional selvedge, which carries the name of the fabric or name of manufacturing company, etc

More about selvedge like requirements, need, problems and methods of selvedge formation, etc the reader is suggested to refer Talukdar2 The main purpose of selvedge is to impart strength to fabric and in finishing machines (stenter) the fabric is finished by holding the selvedges either by pins or clips Total number of selvedges will be equal to: 2  number of selvedges on a side

On the other hand body represents the main part or area of fabric which may be dyed/bleached/printed or woven If woven or printed the prints or designs will differ from selvedge Body may also contain certain extra designs

at some places across width (e.g Butta designs in extra weft fabrics)

Total number of ends in body is given by: ends/inch  body width in inches Body and selvedge can be very easily distinguished especially in case

of weaves like sateen, twill, toweling, etc

1.5.2 Face vs back

Every fabric is characterized by face and back sides It depends on the condition or state of fabric For example, in the case of dyed or bleached/mercerized goods both face and back are same, if printing is one side, then face is the side where print is observed It is necessary to identify face as fabric analysis is normally done on face side only

Face and back are easily distinguished in case of warp faced or weft faced weaves For example, 3/1 or 1/3 or 5-end sateen, etc face and back can also

be distinguished in complex structures like extra thread figuring (e.g warp

or extra weft), backed cloth, double cloth, tile fabrics, Bedford cods/piques,

velveteens/velvets, etc But face and back cannot be identified in plain weave (1/1), gauge and leno, equi-faced weaves (2/2 or 3/3, etc.).

1.5.3 Warp and weft

Warp differs from weft in fabric with respect to its position Warp and weft do differ on many grounds like twist multiplier, tension during fabric formation, preparation of warp and weft for weaving, etc However, from fabric structure point of view we look for count of threads (linear density) Majority of the cases warp and weft counts are same (nominal) even though actual counts differ It should be noted specially in plain weave or fabrics the counts are retained same to get approximately square set fabrics and all the commercial plain sorts belong to category (sort: in industry each type of fabric is called as sort and is given a number known as sort number for its identification)

1.5.4 Width and weight

In the olden days, fabrics were bold on weight basis and even now silk fabrics are selected by consumers on weight basis only However, all fabrics are identified or specified by ‘width’ expressed generally in inches All fabrics are classified into various classes based on width like narrow, medium, wider and broad width cloths Today in market we have ribbons, tapes, honey comb towels (28–32), terry towels (30–35), shirting (nearly 44–46), suiting (58–60), bed spreads (58–64), widths of bed spreads for double caught, sheeting’s up to 330 cm, etc

It is well known fact that fabric width reduces as it passes through various wet processing stages Today in chemical processing a pre shrunk process (zero-zero finish or sanfrorising) is available to prevent fabric from further shrinkage during use

Width refers to the distance between two selvedges of a fabric, which may

be unfinished (grey loom state) or finished Hence, if it is necessary to produce

or plan for production of a fabric, calculations are made from finished state

in reverse direction It should also be mentioned here that indeed fabric width has made it mandatory to manufacture loom of a specific reed space and this

is true in shuttles weaving and even in non-woven also (needle loom)

1.5.5 Expression of weight

Weight is an important measure for a fabric plain cloth which is classified (into light weight, medium weight and heavy weight) based on weight Fabric weight can be estimated by different routes like

(a) Direct method or Arial density (it measures the length, width and weight),

2

2

Weight in gramsweight (g/m ) =

Area in m

(b) Template method or Linear density (using GSM cutter) or quadrant balance method: Fabric of specified area is cut and hung on to the hook

of the instrument, which reads the weight (03/yd2 or g/m2)

(c) Empirical method (Prof D.V Muniswamy’s formulae): Fabric weight can be expressed either in ounces per square yard or grams per square meter as the case may be Here, one should note that either weight

of warp and weft may be found out separately and added finally or computed at the same time as shown below:

2

1 1 1 2 2 2

(g/m ) 0.1[ (1 ) (1 )],

where n1, n2 are ends and picks per cm, N1 and N2 yarn count in tex, C1

and C2 crimp of warp and weft in percentages

where n1, n2 are ends/inch, picks/inch, N1, N2 are English counts, C1, C2

are yarn crimps (%)

Illustrative examples are given below

1 Calculate the weight of the fabric if construction is 22s  18s; 64  60; 6.5  8.5

Weight in oz/yd2 = 0.6857 [64/22  (1 + 6.5/100) + 60/18  (1 + 8.5/100)] = 4.60 oz/yd2

2 Consider a cotton fabric of plain weave with data as:

Warp count N1 = 25 tex, end/cm n1 = 28, warp crimp C1 = 6% and weft count N2 = 15 tex, n2 picks/cm 30, weft crimp C2 = 8%

The areal density of this fabric in g/m2 is

W = 0.1 {28  25 (1 + 0.06) + 15  30 (1 + 0.08)} = 122.8

Or warp and weft weight can be found separately as follows:

The mass of warp per square meter = 25  280 (1+0.06) 102 = 74.2 gThe mass of weft per square meter = 15  300 (1+0.08) 102 = 48.6 gThe density = 4.2 + 48.6 = 122.8

Weight is also a measure to specify quality in weaving and processing units (e.g 6 kg quality – 100% polyester dress material)

Weight of fabric is governed by a number of factors like: type of fibre, nature of fibre, type of yarn, count and many other factors, threads/cm It should be noted that while discussing weight, even the finish applied to the final fabric is also considered as in some cases the weight is increased by adding weighting agents or glazing agents in finishing.

1.5.6 Weave

Weave is defined as interlacement of warp and weft and can be represented

by m/n, where m = number of up and n = number of down If m = n, it is

equi-faced weave (e.g 2/2/, 3/3, 4/4), if m > n, it is warp-faced weave (3/1 or 2/1)

and if m < n, it is weft-faced weave (1/2 or 2/3 or 1/3).

Warp-faced and weft-faced weaves are used in respective constructions Weaves can be used to represent either single-layered structure or multi-layered structure Combination of two or more weaves can be used as modification of basic weave (e.g crepe weaves by super imposing, double cloth–using face and back weave, etc.) Weave always represents the minimum or repeat size

of interlacements

1.5.7 Threads/unit area (reed  pick) and cover

Cover factor of a fabric greatly depends on count and threads/cm or inch Let ‘n1’ be the ends/unit area and ‘n2’ be the picks/unit area then n1  n2 is (pronounced as ends/unit area and picks/unit area) threads/unit area or thread count If n1 > n2, it is a warp-faced construction (e.g poplin of plain sort 112

 72, sheeting of plain sort 52  44), if n1 < n2, it is a weft-faced construction (e.g casement of plain sort 58 picks and 48 ends) and if n1 = n2, it is equi-faced construction (e.g 80 ends and 80 picks of long cloth–plain sort), etc

It should be noted very clearly that majority of fabric constructions are warp faced in weaving (reed count higher than pick wheel) and if reed count is lower than pick wheel bumping conditions present (a method to improve the cover factor) In weaving threads/cm or unit area is generally represented by REED  PICK (pronounced as reed and pick)

Cover factor is defined as the factor which expresses the extent to which the threads are covered in a fabric Thus, low cover indicates open structure, medium cover indicates moderate structure and close set or high cover indicates

a very close construction like 125 ends  92 (silk saree) picks or even 190 ends

 100 picks (sateen construction) It should be noted that based on cover, some

of the fabric applications are observed (e.g curtain cloth – open set)

1.5.8 Yarn crimp (woven fabric)

Weaving is the interlacement of warp and weft, in which each thread will pass over or under the other depending on the weave or order of interlacement,

resulting in yarn waviness known as crimp Due to this, the warp and weft threads have a wavy shape in the fabric The crimp depends on a number of variables like: Warp tension in warp yarn let-off, yarn count, type of yarn (single

or double), nature of fibres, twist of warp and weft, type of weave, etc The crimp of threads is expressed by the extent of waviness and estimated by the extended length in relation to control length and is recorded crimp or take-up.Crimp C, is calculated by expressing the difference between the straightened

thread length, L, and sample length, S, as a percentage of sample length,

100%

L S C S

100%

L S t

a specific length of fabric, crimp of warp and weft threads should be measured

in woven fabric Crimp of yarn in a particular fabric depends also on the sett

It should be noted that crimp is a very important economic measure and fabric handle when expressed as total hand value does include the crimp ratios of warp and weft A number of research publications are reported in analyzing the effect of crimp ratios due to different weaves on fabric mechanical and physical properties To get the same strength, for example, in warp and weft direction

in the fabric of square sett, the crimps should be balanced by controlling the tension of warp on the loom Sometimes, it is required to produce the fabric with different crimps in warp and weft The increase of crimp in one direction

of the fabric reduces it in another direction Some changes of the crimp ratio are possible not only in weaving, but also in finishing The width of fabric decreases and the weft crimp increases when the fabric is stretched in the warp direction There is a close relation between the ratio of crimps and the thickness of fabric

By changing this ratio, the mutual displacement of the warp and weft threads, normal to the plane of fabric, takes place Due to this, either warp or weft floats can be produced on both sides of the plain weave fabric

1.6 Fabric shrinkage

Any fabric shrinks in different states, from loom state onwards to the stage till

it is finished It can be recalled that width of warp on beam (weavers beam) is

different from width in reed, width of fabric on front rest differs from width

in reed, width on cloth roller differs from relaxed width and finished width

is smaller than grey width Answer for all these changes is ‘shrinkage’, of cloth width wise and length wise In some cases fabric shrinkage is high and noticeable, e.g 10s warp sized with 10%, 34s or 40s reed, 8 or 10 pick wheel using 2s roving as weft to produce ‘chaddars’ or thick bed sheets When grey fabric subjected to preparatory process like desizing, scouring, bleaching or mercerizing, fabric undergo shrinkage Thus, if a cloth is finished, we need to calculate from reverse side to arrive at width of warp on beam

Example 1: The finished width of a suiting fabric was found to be 58.45 and

shrinkage at different stages was as follows: from dyeing to finishing 0.8%, from preparatory to dyeing 1.0% and from grey to preparatory 1.5% suggest suitable reed space for the sort

Solution: The width is calculated from finished stage.

W1 = cloth width (1 + C2) (considering the weft crimp as nearly equal to shrinkage in weft direction)

0.858.45 1

10058.91 ,

′′

=

The suitable reed space is 64 RS

1.6.1 Method of notation of structure or design

The interlacing pattern of the warp and weft is known as the weave The unit

of weave construction is an intersection of warp thread and weft thread Two kinds of interlacing are possible The first kind of warp over weft is called warp overlap and the second kind of interlacing weft over warp is called weft overlap The interlacing is achieved by movement of the warp threads

in vertical plane The warp thread must be lifted to obtain a warp overlap, in this case the weft thread is inserted under the warp When the warp thread

is lowered, the weft thread is inserted above this warp thread and the weft overlap is obtained (Fig 1.2)

Figure 1.2 Methods of notation of fabric structure.

There are two practical methods of weave representation: linear and canvas In the linear method each warp thread is represented by a vertical line and each weft thread by a horizontal line The point of intersection of lines corresponding to a warp overlap is marked by a dot, and the point of intersection corresponding to a weft overlap remains unmarked This is a simple method, nevertheless, it is rather seldom used because the designer has

to draw plenty of vertical and horizontal lines by hand It takes time

In the canvas method a squared paper is employed, on which each vertical space represents a warp thread, and each horizontal space, a weft thread Each square, therefore, indicates an intersection of warp and weft threads To show the warp overlap, a square is filled in or shaded The blank square indicates that the weft thread is placed over the warp, i.e weft overlap Several types

of marks may be used to indicate the warp overlap In some cases digit 1 is used to indicate the warp overlap, and digit 0 to indicate the weft overlap, and the weave diagram becomes a matrix which is a convenient form for the computer For interlacing, the threads must cross each other, passing over

or under the threads of another system Therefore, in each full repeat of the weave every vertical space and every horizontal space must have at least one mark and at least one blank, otherwise the threads do not interlace but form loose floats on the face or wrong side of the fabric

Design or interlacement order can be represented through various means like cross-sections, thread interlacement diagram or universal notation X indicates warp up and (blank) indicates weft up or warp down Figures 1.3–1.7 show the details like: weft cross-sectional views, warp cross-sectional views, ‘a’ and ‘b’ system of fabric notation, interlacement or thread diagram for Figure 1.1

If a warp or weft appears more than two times, it is referred as ‘float’ The firmness of any fabric do depend on float Generally more the number of intersections like in plain weave (1/1), the firmer is the fabric On the other hand floating weaves like sateen or satin are not firmer However, in certain cases like in toweling fabrics, it is desired to have floats for better moisture absorption In advanced or complex woven fabrics like double or treble cloth,

it is necessary to have floats, as the binding points or stitching points are selected in between floats

Figure 1.3 Universal cross-blank system of notation.

Figure 1.4 Weft cross-sectional views of 1st and 3rd ends.

Figure 1.5 Warp cross-sectional views of 1st and 4th picks.

(a) Warp up, (b) Weft up

Figure 1.6 ‘a’ and ‘b’ system of fabric notation.

Figure 1.7 Interlacement or thread diagram for Figure 1.1.

1.7 Weave repeat

In any interlacement the order of intersections will start appearing the same after some point which may be few ends and picks and such an appearance

is known as repeat For example, in a plain weave as shown below repeating

on two ends and two picks even though the weave is shown on more number

of ends and picks Indeed, it is this size of the weave or repeat indicates the suitable loom equipment like additional tappets, dobby, jacquard, etc The repeat of weave is a complete element of the weave Repeat is a quantitative characteristic of weave It is customary to represent only one repeat of weave

on point paper Repeat of weave is used as a basis to construct the woven fabric of required size It is defined by warp repeat and weft repeat The warp repeat is a minimal number of warp threads after which the sequence of warp threads with a different interlacing repeats The weft repeat may be defined analogically In some weaves the warp repeat is equal to the weft repeat In others the warp repeat differs from the weft repeat The weave of fabric is determined by a certain arrangement of overlaps In the canvas method of weave representation the weave appears in an abstract mathematical form as

a combination of painted and blank squares Full characteristic of a weave includes not only the repeat, but also a shift or move Shift is the distance from a square on one horizontal space to the corresponding square on the next horizontal space Crepe weave has variable shifts Shift can be positive and negative, depending on the direction of counting Counting from left to right gives positive shift

1.7.1 Selection of reed and its importance

Reed is an important element in weaving irrespective of type of fabric formation technique Reed is a part of beat up mechanism in loom and is selected in relation

to ends/inch desired in fabric and width of the fabric Normally reed count is defined (stockport system) as number of dents per 2 in With 2 ends/dent order, reed count is equal to ends/inches in reed Reeds are selected basically on warp count and number of ends/inch of the finished fabric,

Reed count is given by = 1

2

1

n C

81100+

Another example is commonly sateen cloth using filament warp and filament weft has (194  100) where the weft crimp is minimum, it is better to use 94s

or 98s reed with 4 ends/dent Reed count is available with maximum value as 120s or 128s, as normally 60% air space is considered, while designing a reed Reed also controls the fabric texture and by using 4 ends/dent, reed marks are observed in grey fabric These marks can be eliminated if fabric is subjected

to chemical processing

1.8 Elements of fabric structure

Design: It is defined as the plan of interlacement of warp and weft (if it is

referred to woven design) or the coloured arrangement of motifs on a suitable basis (if it is referred to a printed or painted design)

Draft: It is defined as the order of drawing ends through heald eyes of the

heald shaft Normally one end is drawn/eye only in case of weft rib/matt (2 e nds are drawn)

Denting: It is a plan showing the order of drawing of warp ends through the

dent of reed (Normally, we draw 2 ends/dent or 2 or one dent 3 in other dent

or group dent as case may be)

Lifting: It is defined as the plan of order of lifting of heald shafts on each pick

based on warp ‘up’ in design

1.9 Design or interlacement fashion (discussion is with respect to weaving only)

Design or structure of a fabric is nothing but the plan of interlacing of warp and weft This depends on particular weave or type or class of weave In this regard it is to be noted that every weave or structure is constructed or represented by a specific principle Of course the basic weave or interlacing order is modified to suit the specific end use and modified designs are called

as respective modification or extension The appearance of weave or design depends on the type of the weave, for example, twills are characterized by diagonal line, sateens are featured by dense appearance, etc Sometimes the applications dictate the appearance, for example, a furnishing fabric is produced with zigzag or curved or diamond twill

1.9.1 Draft or drawing plan or drawing in draft

The weave is formed by interlacing the warp and weft threads through the shedding process in weaving which is achieved on the loom by raising and