126 woollen and worsted woven fabric design

126 Woollen and Worsted Woven Fabric Design Số trang: 151 trang Ngôn ngữ: English ---------------------------------------------------- Description Today it is as essential as ever to design, develop and produce saleable and commercially sound woven fabrics within considerable financial restraints. However, in teaching woven fabric design, emphasis appears to have shifted away from the practicalities of cloth construction and design development. This practical handbook provides explanations and answers to some of the technical and practical problems encountered in the development, design and manufacture of woollen and worsted woven fabrics.

Woollen and worsted woven fabric design

Woollen and worsted woven

E Grant Gilligan

CRC Press Boca Raton Boston New York Washington, D.C

W O O D H E A D P U B L I S H I N G L I M I T E D

Published by Woodhead Publishing Limited in association with The Textile Institute

Woodhead Publishing Limited, Abington Hall, Atington

Cambridge CB 1 6AH, England

www woodhead-publishing.com

First published 2004, Woodhead Publishing Ltd and CRC Press LLC

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Woodhead Publishing ISBN 1 85573 743 4

CRC Press ISBN 0-8493-2587-0

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Printed by Antony Rowe Ltd, Chippenham, Wiltshire, UK

Contents

Preface vii

List of tables xi

List of figures ix 1 Woollen and worsted weaving yarns 1

The woollen process 1

Micron suitability for woollen apparel end use 4

Number of fibres in yarn cross-section 5

Direct yarn numbering system 6

Calculate Direct count from a given length and weight of yarn 7

1.10 Convert Direct (Tex) to Direct (Denier) 7

1.1 1 Convert Direct (Tex) to Indirect 7

1.12 Calculate average yarn counts in the Direct system 8

1.13 Resultant yam counts in the Direct system 9

1.1 Introduction 1

1.2 Woollen and worsted systems 1

1.3 1.4 The worsted process 3

1.5 1.6 1.7 1.8 1.9 Twist in single and folded worsted yams 6

1.14 Indirect yarn numbering system 10

1.15 Calculate Indirect count from a given length and weight of yam 10

1.16 Convert Indirect to Indirect 11

1.17 Calculate average yarn counts in the Indirect system 11

1.18 Resultant yam counts in the Indirect system 12

1.19 Yarn twist calculations 13

1.20 Yarn testing 14

2 Woven fabric construction 15

Relationship between yarn count and thickness 15

setting 18

Angle of curvature theory 20

Law’s cloth setting formulae 22

yarns 23

Suggested in-loom making particulars for menswear worsted fabrics 33

2.1 Introduction 15

2.2 2.3 Relationship between frequency of interlacings and density of fabric 18

2.4 Diameter reciprocal weave value and percentage reduction below maximum 2.5 Ashenhurst’s cloth setting formula 19

2.6 2.7 2.8 Different fabric weights densities and in-loom particulars using woollen 2.9 2.10 Changing cloth weights and settings 39

2.1 1 Similar cloths formulae 41

2.12 How to calculate warp and weft weights for piece and sample length production 46

vi Contents

2.13 Influences on both weight and dimensional changes in woven fabrics 47

2.14 Finished cloth analysis 48

2.15 How to calculate in-loom particulars from finished state 50

2.16 How to determine finished fabric weight in grammes per linear metre at standard finished width 51

3 Woven fabric design 53

3.3 Basic weaves 55

Simple warp and weft colour effects 77

Drafting and pegging (English system) 85

3.1 Introduction 53 3.2 The weaving process 53

3.4 3.5 3.6 Sleying (or Denting) 94

4 Design and fabric development 95

4.1 Introduction 95 4.2 4.3 Section blanket making 98

4.4 Section blanket design and colour layouts 104

4.6 Common drafts 117

The role of the woven fabric designer 95

4.5 Common warps 110

References 135

Index 137

Preface

After a working lifetime of more than forty years in various woollen and worsted weaving mills in Scotland and Yorkshire, plus five years with the International Wool Secretariat, I felt

in retirement a desire to make some of that experience available to others

My work in the weaving mills consisted of marketing, designing, manufacturing and selling womenswear and menswear apparel fabrics for the markets of the UK, Europe and the United States

During my five years with IWS based at the Development Centre in Ilkley I was employed

as Fabric Manager in the developing countries area, travelling extensively to work with the

larger woollen and worsted weaving mills in India, Turkey, Algeria, Egypt and Morocco

It had been my experience in the weaving industry that many students on completion of their studies in design and technology were ill prepared in the practicalities of woven fabric construction, design and development I found that when they came into industry for the first time, they had to rely heavily on the practical experience of an older generation of fast-

disappearing, woven fabric designers and manufacturers to compensate for their shortcomings Training of this older generation had always concentrated on the technical and practical side of cloth making rather than the aesthetic which appears to be the case today If not addressed, this situation worldwide could only escalate

This book is my attempt to improve matters by providing explanations and answers to some

of the technical and practical problems encountered in the development, design and manufacture of woven fabrics

E Grant Gilligan

Figures

2.1

2.2

2.3

2.4

2.5

2.6

2.7

2.8

2.9

2.10

Yarns A and B have the same weight and volume but different yarn counts 15

Yarn A with a relative diameter of six assume the yarn count is unknown 16

Yarn B with a relative diameter of three assume the yarn count is 25 Tex 17

Yarn A with a relative diameter of six assume the yarn count is unknown 17

Yarn B with a relative diameter of three assume yarn count is 16 sks Yorkshire woollen 17

Cross-section of 24 threads side by side just touching in the space of one inch 18

Plain we ave interlacing allows only 12 threads in the space of one inch 18

In 3/3 twill only six interlacings provides space for 18 threads in the space of one inch 18

The square of the hypotenuse on a right-angled triangle is equivalent to the sum In 2/2 twill there is sufficient space to allow 16 threads in the space of one inch 18

of the sauares of the other two sides 21

2.1 l a Yarn diameter takes up 4 squares on point paper 39

2.1 lc Yarn diameter takes up 6 squares on point paper 39

2.1 1 b Yarn diameter takes up 3 squares on point paper 39

3.1 3.2 3.3 3.4 3.5 3.7 3.8 The basic requirements and principles of the weaving process 53

Plain weave as represented on point paper 55

Commoin twill as represented on point paper 57

Twill weaves (continued) 59

Terms used to describe fabric interlacings 55

Plain weave and derivatives 56

3.6 Twill weaves 58

A sateen weave as represented on point paper 60

3.9 Sateen weaves 61

3.10 Secondary weaves 62

3.12 Basket weaves (or entwining twills) 64

3.13 Whipcords 65

Extra warp figuring 68

3.16 Double plains 69

Double plains (continued) 71

3.20 Double plains (continued) 74

3.22 Extra warp stitched double cloths 76

Plain we ave colouring arrangements 78

Plain weave colouring arrangements (continued) 79

3.1 1 Secondary weaves (continued) 63

3.14 Backed cloths 67

3.15 3.17 Double plains (continued) 70

3.18 3.19 Double plains (continued) 72

3.21 Cramme.d line stripes 75

3.23 3.24 3.25 Plain weave colouring arrangements (continued) 80

3.26 2/2 twill colouring arrangements 81

x Figures

3.27

3.28

3.29

3.30

3.3 1

3.32

3.33

3.34

4.1

4.2

4.3

4.4

4.5

4.6

4.7

4.8

4.9

4.10

4.11

4.12

4.13

4.14

4.15

4.16

4.17

4.18

4.19

4.20

4.21

4.22

4.23

4.24

4.25

4.26

4.27

4.28

4.29

4.30

4.3 1

4.32

2/2 twill colouring arrangements (continued) 82

2/2 twill colouring arrangements (continued) 83

Colouring arrangements for other weaves 84

Elementary example of design draft and peg plan 86

Designs drafts and peg plans for two simple herringbone effects 88

Example of a slightly more complex draft 90

Various types of drafts 92

Design draft and peg plan for a herringbone design combined with another 93

Five shades of grey fabric from three shades of grey yarn 97

‘In-loom’ dimensions for a three warp, three weft section blanket 99

‘Finished’ dimensions of a three warp, three weft section blanket 100

Pattern material available from one section of a three warp, three weft blanket 101

Unavoidable wastage in section blanket making 103

Contrasting warp and weft showing herringbone design effect 105

Dogtooth design with classic 4 & 4 colquring 107

Dogtooth design in 4 & 4 gunclub colouring 108

Glen check (or Prince of Wales check) with a gunclub colouring arrangement 109

Three different warp and weft set-in arrangements 111

Only three colourways show the herringbone design effect 106

Three colours moved up one place in each colourway 112

Single warp section blanket 113

Single multicoloured warp section blanket 114

Four different designs from a single warp 115

Four designs in white, grey and black combination on a single warp 116

Selection of designs which will weave on an 8 shaft straight draft 118

Selection of designs which will weave on a 16 shaft straight draft 119

Respective peg plans for designs in figure 4.19 121

Weaves using 2/2 twill standard interlacings in warp and woven from same draft 120

Designs which can be woven from the same 10 shaft draft 122

Designs which can be woven from the same 10 shaft draft (continued) 123

Designs which can be woven from the same 10 shaft draft (continued) 124

Designs which can be woven from the same 10 shaft draft (continued) 125

Peg plans for previous eighteen designs 126

Peg plans for previous eighteen designs (continued) 127

Different stripe designs from same 12 shaft draft 129

Different stripe designs from same 12 shaft draft (continued) 130

Different check designs from same 16 shaft draft 131

Different check designs from same 16 shaft draft (continued) 132

Different check designs from same 16 shaft draft (continued) 133

Different check designs from same 16 shaft draft (continued) 134

Tables

1.1

1.2

1.3

1.4

2.1

2.2

2.3

2.4

2.5

2.6

2.7

2.8

2.9

4.1

4.2

Micron suitability for woollen apparel end use 4

Worsted yarn fibres per cross-section 5

Twist classification 6

Indirect yarn numbering systems 10

‘In-loom’ making particulars for different menswear jacketings made from the same ‘In-loom’ making particulars for different fabrics made fram the same single Shetland ‘In-loom’ making particulars for two different fabrics using the same two-ply single lambswool yarn 25

yarn 26

Shetland yarn 27

‘In-loom’ making particulars for traditional Donegal cloths 28

‘In-loom’ making particulars for two lightweight worsted cloths 30

‘In-loom’ making particulars for two Cheviot cloths, one with a single yarn and the other with a two-ply version of the same yarn 29

‘In-loom’ making particulars for four novelty tweed jacketings and coatings for womenswear 32

‘In-loom’ making particulars for four menswear worsted suiting cloths in plain weave 34

‘In-loom’ making particulars for another four menswear worsted suiting cloths but this time in 212 twill 37

Menswear fabrics in 2/52 nm worsted yarn 96

Womenswear fabrics using 8.5 nm Shetland yarn 96

References

1 Denton, M J and Daniels, P N (eds.) Textile Terms and Definitions, 10' edition, Manchester: The Textile Institute, 1995

1 Woollen and worsted weaving yarns

1.1 Introduction

Some knowledge of yarns and yarn counts would appear to be a prerequisite in any study of woven fabric design and manufacture and this first section starts with a brief account of the yarn manufacturing processes of both woollen and worsted systems

There are two yarn numbering systems, the Indirect system which is seldom used now and the Direct system Very few spinners today will be familiar with the Indirect Galashiels and Yorkshire woollen yarn systems, but it is quite likely that in many mills in Scotland and Yorkshire, records still exist of past successful cloths containing yarn details in these old systems So if for no other reason, an ability to convert these yarn counts to the present day

Direct system would be useful

Methods of calculating the average yarn count (where more than one count is used), and the resultant yarn count (when different yarn counts are twisted together) are provided in this section Examples are given in both Direct and Indirect yarn numbering systems

1.2 Woollen and worsted systems

The basic difference between the two is that in the Worsted system all short fibres are removed and the remaining long ones are aligned parallel In the Woollen system there is no

removal of short fibres, so some fibres lie parallel and others randomly

The following from Textile Terms and Definitions (loth edition)’ describe differences between the two systems:

Some would say that the terms ‘woollen’ and ‘worsted’ have become system descriptive, with ‘wool’ being added to describe content - for example, ‘wool worsted’ Woollen yarns being so rarely 100% wool, a description of the blend is usually used if required - for example, 100% wool woollen spun or 100% wool woollen

Woollen, woollen yarn or woollen fabric is descriptive of the fibre - that is wool fibre spun on the woollen system

Woollen spun, woollen type fabric or condenser spun is descriptive of the system - that is any fibre spun on the woollen system

Worsted, worsted yam or worstedfabric is descriptive of the fibre - that is wool fibre spun on the worsted system

Worsted spun or worsted type fabric is descriptive of the system

1.3 The woollen process

A woollen fabric (as distinct from a worsted one) is made from yarns comprising of wool fibres of variable length, which have been spun on the condenser or woollen spun system The fibres are allowed to lie haphazardly in spinning and the resultant yarns have a roughish appearance and full handle Although the raw material for both woollen and worsted yarns is wool fibre, there are important differences In woollen spinning a wide range of shorter wool types can be used in varying proportions in a blend, together with a limited amount of re- processed or re-used wool in order to reduce the cost In worsted spinning only pure new

2 Woollen and worsted woven fabric design

wool fibres of the longer type are used Certain man-made fibres such as polyester can be blended in varying proportions with pure new wool and spun on either woollen or worsted systems, but such yarns will be neither ‘woollen’ nor ‘worsted’

The main processes in woollen yarn production are described briefly as follows:

Sorting: This was at one time a highly-skilled manual operation to select and divide the fleece into different qualities It is now rarely used for that purpose, but occasionally to remove heavily contaminated, matted or weathered wool and heavily stained or pigmented patches

Scouring: Wool in its raw or greasy state is cleaned by mechanically passing it through a series of scouring bowls containing hot water and detergent, then rinsing and drying The main contaminates removed during this process are wool grease (lanolin), animal sweat (suint), animal wastes and mineral dirt picked up from the grazing area Depending on the country of origin, sheep wool type, fibre length and fineness, a minimum of 20% of the greasy wool weight will be lost during scouring In extreme cases only 20% of the greasy wool weight might be wool fibre The average Australian wool yields 65% clean, but this figure is slowly rising as farming methods improve

Carbonising: After scouring some wools contain seeds previously picked up by the sheep and these are removed by carbonising This is a process that carefully treats the scoured wool with acid, dries it and then crushes the seeds or burrs into a powder that falls from the wool

As carbonising tends to weaken and discolour wool, it is processed as a small percentage of a blend

Blending: This describes the mixing of different fibre lots, which will provide the required quality and performance characteristics of the end product, at a specific price Fibre lubricants are added at this time to improve processing performance Depending on blend and end

product, between 2% and 15% oil and anti-static additives may be applied

Carding and Condensing: The blended wool fibres are disentangled and mixed by passing

through a series of large cylinders and rollers clothed with wire teeth As the fibres pass along the card, spacing between the rollers is reduced, the wire teeth become finer and roller speeds increase The material is transformed into an even web of fibres which is split lengthways into strands of untwisted slubbing, then wound onto spools in preparation for spinning

Spinning: Twist is added to the untwisted slubbings to convert them into strong, single yarns on the spinning machine The mule spinning machine has a complex working action and is now more or less obsolete after the arrival of the more productive ring spinning frame The mule consists of a carriage that travels backwards and forwards across the floor, drawing out the slubbing to the required thickness of yarn, whilst rotating spindles twist and wind the yarn onto tubes Ring spinning frames have a higher production rate and larger take-up packages and perform the same functions as the mule, but on a faster and continuous basis However, the mule produces a better yarn than the ring frame for a given raw material and quality requirement Improved production speeds gained from more sophisticated engineering methods and computer control has resulted in a renaissance for mule spinning

Twisting:

yarns) for increased thickness, strength or effect

The resultant spun yarn can be used in single form, or folded with itself (or other

Woollen and worsted weaving yarns 3

Dyeing:

the type of fabric required

This may be carried out on loose fibre, spun yarn or woven cloth, depending on

1.4 The worsted process

A worsted fabric is an all wool cloth made from yarns produced on the worsted spinning

system This system for producing yarns from staple fibres has many more operational stages than those required for woollen yarn spinning In worsted yarn spinning the drawing out operation to f6rm yarn employs several stages of drafting, together with a combing operation This produces a yarn in which the fibres lie as parallel to each other as possible, after removal

of the shorter fibres The resultant yarn has a smooth, slick handle and appearance as well as good strength Worsted yam spinning produces lighter and finer yarns and fabrics than woollen yarn spinning from the same fibre micron Wool can be blended with selected man- made fibres and the resultant yarns combine the desirable properties of the components For example, in a blend of wool and polyester, the fabric would have the superb handle and drape

of wool, plus the easy care properties of the polyester

The early processes in the manufacture of worsted yarns are basically the same as for woollen yarns, namely blending, scouring and carding There is however one difference in the blending process The components in a worsted blend are combined in their greasy state and are usually of a similar quality, unlike a woollen blend, so no special blending is necessary since adequate: mixing takes place in subsequent processing

The extra processes in worsted yarn spinning after carding are described briefly as follows:

of them between two pairs of rollers, to straighten the fibres Between the pairs of rollers are pinned bars known as fallers, which control the fibre during drafting and improve the parallelism of the fibre

slivers are fed into a combing mechanism, which removes most of the short fibres (noils) and further straightens the fibres, making them lie parallel to each other The combed slivers are thereafter referred to as ‘tops’

Finisher Gilling: By using further gill stages, the tops are blended and arrive at a specified and uniform linear density They can then be sold to spinners for drawing and twisting into yarn

Dyeing: If coloured tops are required, they must be dyed before drawing and spinning, by forcing a dyeing solution through them After further gilling and combing they are ready to be drawn and spun into yarn

Drawing: The main objective in the drawing process is to gradually reduce the thickness of the top in three or four stages, to a roving from which yarn is spun This is done by gill box drawing The roving frame, the intermediate stage between gilling and spinning, drafts a fine sliver to a thickness which is suitable for the spinning frame and either adds a few turns of twist, or lightly rubs the sliver with a rolling action before winding the fibre onto a large bobbin The twisting or rubbing action gives the fine fibre assembly some cohesion so that it can be pulled from the bobbin as it feeds into the spinning machine

4 Woollen and worsted woven fabric design

The final count has some bearing on the spinning draft used, as will the type of fibre used - for example, coarse counts spun from synthetic fibre may be drafted at 35 or more Once the fibre has been drafted, the strand is then twisted and wound onto a package by the ring and traveller unit

34 36

Final yarn processing:

faults in the yarn, such as thick and thin places and this operation is known as clearing

Winding machnes are fitted with devices for detecting and removing

Nearly all single worsted yarns are subsequently two-folded and this gives excellent performance in cloth production The folding of single yarns of different colours can add to the aesthetic features of the yarn

Woollen and worsted weaving yams 5

37.9 47.4 56.8 66.3

1.6 Number of fibres in yarn cross-section

In drafting and spinning, the number of fibres in the cross-section of a yarn is a factor of great importance Table 1.2 shows typical numbers of fibres per cross-section in worsted yarns and how they are calculated

It is rare to see wool worsted single yarns with more than 42 fibres in the yarn cross- section due to the high cost of finer wool fibres Only at microns greater than about 24, where the differential between microns is small, would more than 42 be used In synthetic yarn production, where the raw material is relatively cheap and finer fibres have a smaller price ratio, then higher numbers of fibres in yam cross-section may be seen

9 16.9 x Tex Number of fibres per cross-section = micron2

Table 1.2 Worsted yam fibres per cross-section

Fibre diameter

(microns)

Yarn count (Tex)

25

30

35

6 Woollen and worsted woven fabric design

1.7 Twist in single and folded worsted yarns

Table 1.3 Twist classification

Approximate folding twist

in relation to single twist

0.67 x single spinning twist

0.50 x single stinning twist

1.00 x single spinning twist

1 S O x single spinning twist

The following formula is used to calculate the number of turns per metre to be inserted in a single or two-fold worsted yarn

Turns per metre = 0~ JResultant yam count (nm)

Single yarn = = 85 to 95 for plain yarns

2 fold yarn = = 100 to 130 I in pure new wool

Single yarn turns per metre = 95 J60 = 735

e.g 2/60nm

2 fold yam turns per metre = 120 430 = 657

Most two-fold worsted yarns have the folding twist inserted in the opposite direction to single spinning twist Although there are many exceptions, table 1.3 gives a guide to the twist classification of various yarn types

In the Direct system, the yarn count number refers to ‘the weight in grammes of a given length of yarn’ This means the higher the yarn count number, the heavier or thicker the yarn

In the Direct universal Tex system, yam count number indicates ‘the weight in grammes of

1000 metres of yarn’

e.g 30 Tex indicates that 1000 metres of yam weigh 30 grammes,

e.g 50 Tex indicates that 1000 metres of yam weigh 50 grammes,

e.g 70 Tex indicates that 1000 metres of yam weigh 70 grammes

In the Direct denier system, the yarn count number indicates ‘the weight in grammes of 9 000 metres of yarn ’

Decitex (or Dtex) yarn count number indicates ‘the weight in grammes of 10 000 metres of yarn ’

Woollen and worsted weaving yarns 7

1.9 Calculate Direct count from a given length and weight of yarn

C = yarncoiint

L = length of yarn sample (metres)

Wt = weight of yam in units of the system at official regain

L1 = unit of length of the system

Wt x 1.1

length of yarn sample = 100 metres unit of length (Denier) = 9000 metres 1.67 x 9000

C = 100 = 150.3 = 150Denier

Example 2 >weight of yarn sample = 1.75 grammes

length of yam sample = 90 metres unit of length (Tex) = loo0 metres 1.75 x 1000

c = 90 = 19.44Tex

1.10 Convert Direct (Tex) to Direct Denier

Multiply Tex count by 9

Example 1 :30 Tex = 30 x 9 = 270 Denier

Conversely, to (convert Direct (Denier) to Direct (Tex), divide Denier count by 9

Example 4

Example5

180 Denier = 180 / 9 = 20 Tex 450Denier = 45019 = 50Tcx

225 Denier = 225 / 9 = 25 Tex

1.11 Convert Direct (Tex) to Indirect

To convert Tex to any in the Indirect system, the following constants may be used:

1000 x 12 x 454

Tex x 11 x 840 = 590Cottonconstant

8 Woollen and worsted woven fabric design

- 884 - 884 Tex to Worsted = Tex e.g 50Tex 50 = 17.7 Worsted

Tex to Metric = Tex e.g 20Tex 20 = 50 nm Metric

Tex to Yorkshire = Tex e.g 100Tex 100 = 19 sks Yorkshire

Tex (2ply) to Worsted (2ply)

- 884

R 3 8 T e x l 2 = 38 = 23.26 = 2/46 worsted

- 884 R42 Tex I 2 = 42 = 21.05 = 2/42 worsted

- 884 R48 Tex I 2 = 48 = 18.42 = 2/36 worsted

884

-

R52Texl2 = 52 = 17.00 = 2/34 worsted

- 884 R56Texl2 = 56 = 15.78 = 2/32 worsted

1.12 Calculate average yarn counts in the Direct system

To determine the average yarn count of two or more yams, calculate the arithmetical mean as follows:

Example 1 1 thread of 30 Tex

1 thread of 60 Tex

2 threads = 90 Tex

- 90 Average yarncount = 2 = 45Tex

Woollen and worsted weaving yarns 9

Example 2 1 thread of 17 Tex

1 thread of 20 Tex

1 thread of 50 Tex

3 threads = 87 Tex

- 87

Average yarncount = 3 = 29Tex

Example 3 2 threads of 20 Tex

1 thread of 30 Tex ,1 thread of 35 Tex

,4 threads = 105 Tex

- 105 Average yarncount = 4 = 26.25Tex

Example 4 1 thread of 40 Tex

:2 threads of 25 Tex

3 threads of 30 Tex

6 threads = 180 Tex

- 180 Average yarncount = 6 = 30Tex

1.13 Resultant yarn counts in the Direct system

Example 2 60 Tex / 30 Tex -

Example 3 60 Tex / 40 Tex / 30 Tex = R130 Tex / 3

Example 4 20 Tex / 20 Tex / 40 Tex = R80 Tex / 3

Example 5 30 Tex / 30 Tex / 30 Tex = R90 Tex / 3

R75 Tex / 2

-

Example 6 SO Tex / 25 Tex -

Percentage take-up has not been allowed for in the above samples

2 threads of 30 Tex are written as R60 Tex / 2

2 threads of ;!O Tex are written as R40 Tex / 2

3 threads of 100 Tex are written as R300 Tex / 3

2 threads of 300 Denier are written as R600 Denier / 2

10 Woollen and worsted woven fabric design

~~

Name

Worsted

1.14 Indirect yarn numbering system

Table 1.4 Indirect yarn numbering systems

Universal Hanks of 560 yards Per 1 Ib 560 Cotton Universal Hanks of 840 yards Per 1 lb 840

Scotland Cuts of 300 yards Per 1.5 lbs 200 Yorkshire Skeins of 256 yds Per 1 lb 256

1/20 worsted indicates 20 x 560 yards of yam weigh 1 pound

1/40 worsted indicates 40 x 560 yards of yarn weigh 1 pound

1/30 cotton indicates 30 x 840 yards of yarn weigh 1 pound

1/48 cotton indicates 48 x 840 yards of yarn weigh 1 pound

15 cut Galashiels indicates 15 x 200 yards of yarn weigh 1 pound

28 cut Galashiels indicates 28 x 200 yards of yarn weigh 1 pound

16 skeins Yorkshire indicates 16 x 256 yards of yarn weigh 1 pound

24 skeins Yorkshire indicates 24 x 256 yards of yarn weigh 1 pound

30 nm Metric indicates that 30 x 496 yards of yam weigh 1 pound

50 nm Metric indicates that 50 x 496 yards of yam weigh 1 pound

1.15 Calculate Indirect count from a given length and weight of yarn

C = yarncount

L = length of yarn sample (yards)

W = unit of weight of the system

Wt =

S = standard number of the yarn system

weight of yarn sample in units of the system at official regain

L X W

c = W t x S

Woollen and worsted weaving yarns 11

Length of yarn sample = 120 yards Standard no (worsted) = 560 yards Unit of weight (llb.) = 7000 grains

120 x 7000'

C = 50 x 560 = 30 = 2160worsted

Length of yarn sample = 75 yards Standard no (Yorkshire) = 256 yards Unit of weight (llb.) = 7000 grains

75 x 7000

C = 90 x 256 = 22.79 = 23 sks Yorkshire woollen

1.16 Convert Indirect to Indirect

1.17 Calculate! average yarn counts in the Indirect system

1 end of 2/30 worsted (15s)

12 Woollen and worsted woven fabric design

60 units of 20s = 3 x 1 = 3.0

60 units of 15s = 4 x 1 = 4.0

2 = 7.0

60 x 2 Average count = 7.0 = 17.14 = 2/34 worsted

Example 2 1 end of 20 sks Yorkshire woollen

1 end of 30 sks Yorkshire woollen

2 ends of 18 sks Yorkshire woollen

Example 3 1 end of 40s cotton

1 end of 16s worsted 1/16 worsted to Cotton = 840 = 10.67s Cotton

1.18 Resultant yarn counts in the Indirect system

The resultant yarn count is the count of two or more yarns twisted together

Example 1 24 sks Yorkshire / 16 sks Ysrkshire

24 units of 24 sks = 1.00

24 units of 16 sks = 1.50

24 units of ‘x’ = 2.50

24.00 Resultant count = 2.50 = 9.6 sks Yorkshire

Example 2 24 worsted / 32 cotton

First convert 32 cotton to worsted =

32 x 840

560 = 48 worsted

Woollen and worsted weaving yarns 13

48 units of 24s = 2.00

48 units of 48s = 1.00

48 units of ‘x’ = 3.00

48.00 Resultantcount = 3.00 = 16 worsted

Example 3 56 worsted / 48 worsted / 2/80 cotton

40 x 840 Convert 2/80 cotton to worsted = 560 = 60 worsted

Percentage take-up means extra length of single yarns per unit length of folded but has not been included in the foregoing examples However it must be allowed for in any such calculations, in order to give an accurate resultant count

Take-up is variable and depends on the thickness of the component yams and the number

of turns per inch inserted in the twisting operation The more turns per inch inserted, the greater percentage take-up and thicker resultant count

1.19 Yarn twist calculations

A much used calculation is the one to determine the unknown component yarn count in a two ply twist yam, when the other single component yarn count and the resultant count are both known

Indirect systein:

24 metric count and one thread of an unknown count What is the unknown yarn count?

A two ply twist yarn of 8 metric resultant count is composed of one thread of

24 units of 24 metric = 1

24 units of ‘x’ metric = ?

24units of 8 metric = 3 so 24units of ‘x’ metric = 3 - 1 = 2

Therefore the unknown yarn count is equal to 24 divided by 2 = 12 metric

worsted Wha.t is the count of the other component?

A resultant two ply yarn count of 16 worsted has one component yam of 36

144 units of 36 worsted = 4

144 units of ‘x’ worsted = ?

144 units of 16 worsted = 9 so 144 units of ‘x’ worsted = 9 - 4 = 5

14 Woollen and worsted woven fabric design

Therefore the unknown yarn count is equal to 144 divided by 5 = 28.8 worsted

Direct system:

Example 1 A two ply yarn in Tex (Direct system) is composed of one thread of 40 Tex, one thread unknown count and has a resultant count of 100 Tex What is the count of the other component yarn?

The simple answer to this one is 100 minus 40 which is 60 Tex, the count of the unknown yarn

Example 2

thread of 70 Tex and one unknown Tex count The resultant count is 150 Tex

third component as 30 Tex

A three ply yarn in Tex (Direct system) is made up of one thread 50 Tex, one

The unknown yarn count this time is 150 minus 50, minus 70 which gives the count of the

1.20 Yarn testing

In industry today, sophisticated apparatus and methods are used to test and assess the various properties of yarns Whilst it is not within the scope of this publication to deal with such apparatus and test results, it is relevant to list the properties:

Yarn count

Count variation between bobbins

Mean breaking strength

Mean elongation at break

Breaking strength variation

Elongation at break variation

Evenness

Number of thick and thin places and neps

Faults (slubs, fly, piecings etc.)

Hairiness

Twist

Twist variation between bobbins

This chapter has fulfilled the need for knowledge of yarns, yarn counts and yarn manufacturing processes mentioned in the introduction It has presented a general understanding of the subject without an in-depth study as woven fabric designers are unlikely

to be asked to solve carding and spinning problems as there are others better qualified to do The study of both Direct and Indirect yarn numbering systems has concluded that the Direct system is the simpler and more straightforward of the two to use Calculations for average yam count, resultant yarn count and yarn twist are much easier to determine in the Direct system

so

2 Woven fabric construction

2.1 Introduction

The basics of' woven cloth construction are explained in thisBchapter as well as cloth setting rules and formulae There are also various tables that show full making particulars for different fabrics using the same yarn count for womenswear and menswear woven apparel fabrics They are all commercially acceptable fabrics and provide accurate guides when developing cloths in other yarn counts

A very important part of a woven fabric designer's job is that of cloth adjuster and

modifier; where existing fabrics are sometimes required to be made in a different weight, weave, yarn (,or all three), whilst preserving the firmness of the original cloths These changes are almost impossible to carry out correctly without a sound understanding of the necessary formulae This chapter contains several examples of how to use these formulae

At various stages throughout the weaving and finishing processes, changes in fabric weight and dimension take place These changes have to be anticipated and allowed for, so that the finished fabric is delivered to the customer at the standard finished width and within the originally quoted weight in grammes per running metre

Finished cloth analysis is another important subject dealt with here Fabrics obtained from customers and elsewhere are often copied for all sorts of reasons and accurate determination

of the finished properties of such cloths is essential These results are then adjusted to give the necessary in-loom making particulars to accurately reproduce the cloths

The topics in this section address the practical cloth-making responsibilities of the woven fabric designer, rather than the creative and aesthetic ones

2.2 Relationship between yarn count and thickness

Before considering cloth setting formulae it is important to fully understand the relationship between the count of a yarn and its thickness, see figure 2.1 Assuming it is possible to draw out yarn A to four times its original length, resultant yarn B will be thinner with a reduced radius and both yarns will have the same weight and volume but different yarn counts

The weight of 20 crns of yarn B will be the same as 5 crns of yarn A, so 5 crns of yarn B

will weigh one quarter of 5 crns of yarn A If yarn A is say 100 Tex, then drawing it out to

four times its original length makes resultant yam B equal to 25 Tex

2.1 Yarns A and B have the same weight and volume but different yarn counts

16 Woollen and worsted woven fabric design

Volumes of yams A and B are the same, both being equal to the area of cross-section multiplied by length

z A 2 x 1 = ITB’ x 4

A2 = B 2 x 4

As A = B x 2, the radius of yarn A is twice the radius of yarn B, therefore yam A is twice

the thickness of yarn B

In the Direct Tex yarn numbering system, by quartering the yarn count the thickness is halved The example below shows that 25 Tex is half the thickness of 100 Tex From this it can be established that the thickness or diameter of a yarn is directly proportional to the

square root of its count

Diameter of 25 Tex : diameter of 100 Tex = : f i

Having just proved that in the Direct Tex yam numbering system the thickness or diameter

of a yarn is directly proportional to the square root of the count, figures 2.2 and 2.3 and the following equations may explain this more clearly in another way

Woven fabric construction 17

2.3 Yarn B with a relative diameter of three, assume the yarn count is 25 Tex

2.4 Yarn A with a relative diameter of six, assume the yarn count is unknown

2.5 Yarn B with a relative diameter of three, assume yarn count is 16 sks Yorkshire woollen

In the Indirect yarn numbering system the yarn thickness or diameter is inversely proportional to the square root of the count Figures 2.4 and 2.5 explain how using Yorkshire

skeins woollen yarn counts

JCount A Diameter B

JCount A 3

= 2

Count A = 4 skeins Yorkshire woollen

Diameter of :16 sks YSW : diameter of 4 sks YSW = f i : &

= 2 : 4

= 1 : 2

Therefore 16 sks YSW is half the diameter of 4 sks YSW

18 Woollen and worsted woven fabric design

2.3 Relationship between frequency of interlacings and density of fabric

- - - -

2.6 Cross-section of 24 threads side by side just touching in the space of one inch

2.7 Plain weave interlacing allows only 12 threads in the space of one inch

~~

2.8 In 2/2 twill there is sufficient space to allow 16 threads in the space of one inch

2.9 In 3/3 twill only six interlacings provides space for 18 threads in the space of one inch

Figures 2.6 to 2.9 inclusive show clearly that if the same thickness of yarn is used in different weaves, for example, plain weave, 2/2 twill and 3/3 twill, the fewer interlacings there are in

the weave, the greater the number of threads that can be packed into the same space

In order to make the examples as simple as possible, Ashenhurst’s original theory that one interlacing takes up the same space as one thread has been applied This theory was subsequently found to be somewhat inaccurate and replaced by the angle of curvature theory which is dealt with in a later section

2.4 Diameter reciprocal, weave value and percentage reduction below maximum setting

Cloth setting indicates the number of ends and picks per inch (or centimetre), to be inserted during the weaving process It is influenced by the density and thickness of the yarn used and the firmness of the weave

A cloth setting formula comprises three parts:

1) Diameter reciprocal: The first part of the setting formula determines the maximum

number of threads in a particular yarn count that can be laid side by side just touching in the space of one inch

Attempts to establish a relationship between yarn count and diameter reciprocal were made

by Thomas Ashenhurst in the early 1880’s when he provided the following formula for worsted yarns:

Diameter reciprocal = 0.9 JYarn Count xStandard number

This can be applied to any Indirect yarn numbering system, using the appropriate yarn counts and standard numbers

Woven fabric construction 19

2) Weave value: After the diameter reciprocal has provided the number of threads in a

particular yarn count that can be laid side by side in one inch, an allowance is made for the spaces required for warp and weft interlacings in the particular weave to be used This value for any given weave can be determined as follows:

Weave value = F/(F+l), where F = average float

e.g Plain weave = l/(l+l) = 1/2

2/1 twill = 1.5/(1.5+1) = 1 3 2 5

212 twill = 2/(2+1) = 2/3

weave value parts of the formulae, theoretical maximum setting is determined The figure however is further reduced to give the actual number of ends and picks per inch to be

inserted during weaving This percentage figure is based on experience and comparison with other commercially acceptable fabrics

This final reduction influences firmness, drape, handle, weight and suitability of the fabric for its intended end use

2.5 Ashenhurst’s cloth setting formula

Maximum sett = k ,/Yards per pound x F/(F+l) = ends, picks per inch

k value for woollens = 0.84

k value for worsteds = 0.90

k value for cottons = 0.95

Diameter reciprocal (woollens)

and F = average float

= 0.84 Jcount x standard number

Diameter reciprocal (worsteds) = 0.90 Jcount x standard number

Diameter reciprocal (cottons) = 0.95 Jcount xstandard number

Maximum setting (plain weave)

Maximum setting (2/1 twill)

= k ,/yards/lb x YZ

Maximum setting (2/2 twill) = k ,/yards/lb x 2/3

Ashenhurst arrived at a weave value of F/(F+l) by allowing the equivalent of one thread space for each intersection in the weave This was later proved to be inaccurate on two points:

1) The angle of curvature theory showed geometrically that the space occupied by one intersection in a weave was less than the diameter of one thread - actually 0.732 of a diameter See section 2.6

20 Woollen and worsted woven fabric design

2) In floats longer than two it was likely that threads would bunch together and roll over each other to a certain extent, rather than lie conveniently side by side as Ashenhurst had originally assumed, thereby making more ‘space’ than that required for exactly one thread

Later setting theories (such as Law’s) take these points into consideration but Ashenhurst’s original theory, though on the low side for determining maximum ends and picks per inch, remains reasonably accurate for plain weave, 2/1 twill and 2/2 twill

Ashenhurst’s formula for determining diameter reciprocal used the Indirect yarn numbering system, but adjustments can be made to accommodate Direct yam numbering systems such as Tex

Yards per pound of any Tex yarn count can be calculated as follows:

Example 1

weave, 20% below maximum setting

Calculate setting for a fabric using 20 sks Yorkshire woollen yarn in plain

Sett = 0.84 Jyardsnb x F/(F+l) x percentage reduction

= 0.84 420x256 x 95 x 80/100 = 24.04 ends and 24.04 picks per inch

Example 2 Calculate setting for a 2/2 twill fabric, 10% below maximum setting using 2/56 worsted yarn

Sett = 0.90 428x560 x 2/3 x 90/100 = 67.6 ends and 67.6 picks per inch

If ends and picks per centimetre are preferred, calculated ends and picks per inch are simply divided by 2.54

2.6 Angle of curvature theory

In figure 2.10 the angle between adjacent threads at an intersection is assumed to be 30” in

a balanced, square woven cloth

Woven fabric construction 21

2.10 The square of the hypotenuse on a right-angled triangle is equivalent to the sum of the squares of the other two sides

AB = 2 diameters (or 1 diameter plus 2 x ‘/2 diameters) = 2

After the angle of curvature theory Ashenhurst’s new formula for maximum setting

DR x F/(F+I) where DR = diameter reciprocal

became:

F = average float in weave

I = intersection = 0.732

Weave value for plain weave = 1/( M.732) = U1.732

Weave value for 211 twill

Weave value for 212 twill = 2/(2+0.732) = 2/2.732

= 1 S/( 1.5+0.732) = 1.Y2.232

Comparing the original Ashenhurst formula with the later one based on the angle of

Old formulil = 63 X 2/(2+1) = 63 X 2/3 = 42 ends, picks per inch

Later formula = 63 X 2/(2+0.732) = 63 X 212.732 = 46 ends, picks per inch

curvature theory for a 2/2 twill fabric with a DR of 63 below:

Ashenhurst’s original formula (diameter intersection theory) gives firm cloth settings for

plain weave, 2/1 twill and 212 twill but is not used much when the average float is more than

two Law experimented to increase the maximum setting of square sett cloths and came up with the formula J500X yarn count to find the DR for a yarn He also added 5% for each float above two

Below is a comparison between the two theories for an imaginary setting in a 3/3 twill

cloth made with 2/18 worsted yarn count:

22 Woollen and worsted woven fabric design

Ashenhurst for 3/3 twill = 0.9 49x560 x 3/4

Law for 3/3 twill

= 48 ends, picks per inch

= 9500x9 x 3/4 x 1.05 = 53 ends, picks per inch

2.7 Law's cloth setting formulae

Maximum sett = 4500 x C x F/(F+ 1) + 5% for every end in

This is the setting rule generally used in the Worsted industry

the average float above 2

Maximum sett = JG- x F/(F+l) + 5% for every end in the average float above 2 This is the setting rule generally used in the Yorkshire woollen industry

Law's rules for maximum settings in the following weaves:

Self-stitched double cloths:

2/2 twill lFace, lBack double cloth, sateen stitched, reduce face setting by 10%

Twill or crow stitched, reduce face setting by 20%

Double sateen stitched, reduce face setting by 20%

Double twill stitched, reduce face setting by 25%

Double crow stitched, reduce face setting by 25%

Non-square cloths:

Sometimes it is desirable to construct a cloth with a steeper twill than the normal 45" of a square sett cloth and this can be simply done by increasing the number of warp ends per inch

However, the difficult part is to determine the reduced number of weft picks per inch which

will maintain the same degree of firmness in the cloth

For example, a square sett 2/2 twill cloth which might normally have 64 ends and picks per inch can be made instead with 120 ends per inch in order to give a much steeper twill effect

The reduced number of weft picks per inch is calculated as follows:

1 8 z

If X is the increase in ends per inch above square sett, the decrease in picks per inch is

1.8 4 = 1.8 .$56 = 13.5 decrease in picks per inch

Woven fabric construction 23

So the setting required to preserve the firmness of the original square sett cloth will be 120 ends and 50 (64-14) picks per inch

Alternatively, the same square sett 2/2 twill fabric with 64 ends and 64 picks per inch can

be adjusted to say, 96 picks per inch to give a flat twill effect In this case the reduced number

of ends per inch is calculated as follows:

If X is the increase in picks per inch above square sett, then the decrease in ends per inch

is 3.6 f i 3.6 4 s= 3.6 a = 20.36 decrease in ends per inch

Therefore, the setting required to preserve the firmness of the original square sett cloth is

96 picks and 44 (64-20) ends per inch

2.8 Different fabric weights, densities and in-loom particulars using woollen yarns

One yarn count can be used to make at least three different, basic cloths:

In determining cloth setting, care must be taken to ensure that lighter weight versions are not too loosely sett below maximum; otherwise seam slippage might become a problem in garments At the other end of the scale, cloths which are too firmly sett might be difficult to

weave owing to excessive warp end breakages So before actually using cloth setting

formulae it is advisable to consult ‘in house’ fabric making records kept by all woven cloth manufacturers, in order to find a starting point by comparing weight and firmness of commercially acceptable cloths As there is no formula to calculate the required total number

of warp threads in loom to give a standard finished fabric width of 150 crns, the same ‘in house’ records will provide guidance

Cloth setting is more than just calculating the number of warp ends and weft picks per centimetre to be inserted during weaving using a particular yam count and weave structure Desired weight in grammes per linear metre has to be considered, as well as the aforementioned total number of warp ends to produce a cloth of 150 crns finished width Pieces that finish under the standard width will cause problems for the garment maker and might well be rejected Finished widths that are two or three centimetres over 150 crns will probably be acceptable to the customer, but the cloth manufacturer will be giving cloth away

as costings are (calculated for 150 crns finished width

The following series of tables (2.1 to 2.7 inclusive) are given as accurate guides to ‘in-

loom’ making particulars As well as recommended warp and weft details, they show resultant weights in grammes per linear metre and total number of threads required to produce fabrics at standard finished width They also show percentage width shrinkage from ‘in-loom’

width, as well acs finished length yield from a standard 70 metre warp length The cloth setting formula shows how loom ends and picks per centimetre are calculated and then rounded up or down to give the appropriate metric reed and picks per 10 crns to be inserted in loom

24 Woollen and worsted woven fabric design

The data provided in the tables is from commercially acceptable fabrics and serves as an accurate guide for developing other pure new wool woven fabrics

Table 2.1 shows full ‘in-loom’ making particulars for three different menswear jacketing

cloths made from the same single lambswool yarn in 2/2 twill weave They are different in

weight, firmness, drape, handle and price

From the same calculated maximum number of ends and picks per centimetre in loom, Cloth 1 is reduced by 45%, Cloth 2 by 35% and Cloth 3 by 25% Each is then rounded up or

down to give the appropriate metric reed required and number of picks per 10 crns to be

inserted during weaving Note that as percentage reduction below maximum becomes less, settings are firmer and width shrinkages decrease

As previously stated no formula exists with which to calculate the total number of ends required in the warp to give 150 crns standard finished width of cloth Experience of and

comparison with existing commercially acceptable fabrics is essential

Cloths 4, 5, 6 and 7 in table 2.2 are made from the same single Shetland yarn Two of the

cloths are made in plain weave, the other two in 2/2 twill

The cloths in plain weave are sett firmer (see column 14 showing percentage reduction

below maximum setting) and are suitable for womenswear lightweight jackets and skirts The fabrics in 2/2 twill are sett looser and wider in loom and make excellent jacketings for both

womenswear and menswear

Two-ply versions of the above Shetland yarn, one in plain weave the other in 2/2 twill are

featured in table 2.3 Plain weave Cloth 8 is sett 25% below maximum but there is no technical

reason why a reduction of 20% or 30% cannot be used as it is entirely a question of personal preference and experience Heavier Cloth 9 in 2/2 twill is sett wider in loom to allow greater

width shrinkage in finishing and ensure the desirable fuller handle in a womenswear coating

Table 2.4 features four traditional Donegal cloths suitable for both womenswear and

menswear garments Cloths 10 and 11 are made from the same Donegal yarn in plain weave and 2/2 twill respectively Both are ideally suitable for jacketings in the characteristic

homespun look

Cloths 12 and 13 are also in plain weave and 2/2 twill respectively, but this time made

from a typical Donegal yarn twice the thickness of the one used in Cloths 10 and 1 1 Notice

how percentage reduction below maximum setting in both plain weave fabrics is fairly similar, as is also the case with the twills

Two Cheviot wool cloths are featured in table 2.5, one of which, Cloth 15, is made in 2/2

twill from a single Cheviot yarn of 7 nm count warp and weft It is sett 45% below maximum and gives a finished cloth weight of 385 grammes per linear metre 150 crns finished width

This is an ideal jacketing cloth for both men and women

Plain weave Cloth 14 is made with a two-ply version of the same Cheviot yarn, sett firmly

in loom (only 10% below maximum) to give a substantial coating fabric for womenswear

Two lightweight worsted cloths are shown in table 2.6, one in plain weave the other 2/2

twill and both made with the same 2/48 nm worsted yarn Plain weave Cloth 16 is firmly sett

5% below maximum whilst 2/2 twill Cloth 17 is sett looser at 15% below These firmer

settings give the sleek, smooth yet firm handle associated with worsted fabrics and both fabrics are suitable for lightweight menswear jacketings