1

Bangladesh University of Textiles

Project Report

On

Effect of core draft on the properties of core spun yarn

SUPERVISING TEACHER

Mr. Md. Zahidul Islam

Lecturer, Department of Yarn Manufacturing Engineering

Bangladesh University of Textiles

Submitted by

Arif Rahman, ID: 20101001

K. M. Mamunur Rashid, ID: 20101059

Sadikur Rahman Shawpon, ID: 20101060

Ashfaqur Rahman, ID: 20101063

Noman Siddiqui, ID: 20101067

Session: 2012-13

Department of Yarn Manufacturing Engineering

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ACKNOWLEDGEMENT

We are very fortunate that we were well supported and co-operated at all points in our

project work. It is high time we expressed our gratitude to all those who are related to our

work. First of all, we express our heartiest gratitude to the VC of Bangladesh University of

Textiles, Professor Dr. Nitai Chandra Sutradhar. Then we would like to convey our

heartfelt thanks to the Dean of Textile Manufacturing Engineering Faculty, Professor

Masud Ahmed. Needless to say that we are ever indebted to our revered Head of the

Department, Associate Professor Dr. Hosne Ara Begum, Department of Yarn

Manufacturing Engineering for arranging the project work with convenience. We also

express our heartfelt thanks to our supervising teacher, Lecturer, Mr. Md. Zahidul Islam,

Department of Yarn Manufacturing Engineering. We thankfully recall engineer Mr.

Mainul and Mr. Saif of Sinha Rotor Spinning Limited who extended their wholehearted co-

operation regarding data collection.

Above all, we are deeply glad and thankful to all the teachers of our department for extending

a co-operative hand and encouraging the little efforts that we took. We also acknowledge

that we remain utterly responsible for any inadequacy and error that we undoubtedly have

had in this report.

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ABSTRACT

At first, some core spun yarn samples were collected with necessary data which are needed

to begin the project work with effective analysis. The yarns were also separated according to

their count so that an acceptable result can be established for effective use which will help to

carry out further activities depending on the established form of work. Core spun yarn

specifications, machine specifications and the major factors necessary for calculation were

managed and watched with different variations which affect the core spun yarn construction.

Our efforts were developed in a dependable way so that we can easily visualize the resulting

core spun yarn. Finally the core drafting and its effects in the form of yarn properties have

been studied to gather an idea. It has been noted that there is a strong influence of core

drafting on the yarn properties.

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CONTENTS

Chapter Number

Topics Sub-topics Page number

01 Introduction 05-06

02 Objectives 07-08

03 Literature review 09-17 3.1 Definition 10

3.2 Methods of production of core spun yarn 10 3.2.1 Core spun yarn production by ring spinning

11

3.2.2 Core spun yarn production by rotor spinning 12 3.2.3 Core spun yarn production by friction spinning 12

3.2.4 Core spun yarn production by MJS spinning system

13

3.3 The process variables that affect the core spun yarn properties

14

3.3.1 Core sheath ratio 14

3.3.2 Pre- tension to core material 14 3.3.3 Spinning draft 14-15

3.3.4 Number of roving feed 16

3.3.5 Twist 16 3.4 Problems associated with core spinning 16

3.5 End uses 16-17 04 Work plan 18-21

4.1 Material 19-20

4.2 Method and work description 21 05 Experimental

result

22-26

5.1 Fiber properties 23 5.2 Yarn properties 24

5.2.1 Various Properties for different type core spun yarn count

25

5.2.2 Test results of universal strength tester 26 06 Discussion 27-

6.1 Discussion 6.2 Comparison among different yarn counts with

same filament count 29-33

6.3 Comparison between same yarn counts with different filament count

34-36

6.4 Inference 37 07 Conclusion 38-39

08 Reference 40

5

CHAPTER: 01

INTRODUCTION

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INTRODUCTION

Core spun yarn is one of the many types of yarn that are produced around the world. It is

produced with a view to combining the advantageous aspects of two components namely i)

core element and ii) sheath element that form a structured yarn which has first of the

aforementioned components taken as mono or multi filament and the other as a staple fiber

sheath. As stated earlier, the main goal is to combine the good characteristics of two different

fibers in a single yarn. The outer sheath provides the appearance and physical properties of a

yarn produced from staple fibers. On the contrary, the inner core filament gives an improved

strength level and allows the use of lower twist level. The preparation technique of core spun

yarns is simple and can be produced on regular spinning machines with minimum addition of

machine parts to them. With specific end use and required properties in mind, the core cover

element can also be chosen from a variety of fibers. Common core materials include the

continuous filaments of polyester and nylon.

Hence, in a nutshell, core spun yarn can be described as a composite, mixed or blended yarn

consisting of two or more types of filaments at the center which are covered by a natural or

synthetic staple fiber. It can broadly be classified into three classes. I) Filament core spun yarn,

II) Elastomeric core spun yarn and III) Staple core spun yarn.

Due to its extensive usability and better quality provisions, core spun yarn is being produced

increasingly in our country and many factories like Sinha Spinning Limited, Square Spinning

Limited are producing core spun yarn on a regular basis.

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CHAPTER: 02

OBJECTIVES

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OBJECTIVES

i. To know about the raw materials of core spun yarn.

ii. To know about different fibers used in core spun yarn.

iii. To know about core draft.

iv. To discuss physical properties of core and sheath.

v. To discuss the effects of core draft on the properties of yarn.

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CHAPTER: 03

LITERATURE REVIEW

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3.1) DEFINITION

The process by which staple fibers are twisted around a central core forming filament or

staple spun yarn to produce a covering sheath around it is called Core spinning.

Core spun yarn is a structure of two components named the core and the sheath. Generally

continuous mono or multi filament is used for core formation and staple fiber is employed in

the formation of the outer sheath. The use of core spun yarn in production of fabrics increases

their functional properties like strength, durability, comfort etc.

Fig 01: core- sheath structure

3.2) METHODS OF PRODUCTION OF CORE SPUN YARN

Core spun yarn can be produced successfully by many spinning systems each of which have

features with their own conveniences and problems. For example, the conventional ring

spinning is a viably simple and economical process in this regard. But it has difficulty in respect

to core positioning at the center and possibility of major strip back at the subsequent

processes. The feasible methods of core spun yarn production are discussed below.

1. Core spun yarn production on conventional ring frame

a) Single end roving

b) Double end roving

2. Rotor spinning system

3. Tandem spinning system

4. Bobtex spinning system

5. Friction spinning system

6. Airjet spinning system

7. Composite electrostatic spinning system

8. Core-twin spinning system

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3.2.1) Core spun yarn production by ring spinning

A conventional ring frame with suitable modifications is used for core spinning. The

attachment consists of metal plate bent to a shape. One end of the device is fitted on the

roving traverse guide bar such that the relative position of the roving and the core filament

may be kept constant all the time. There is a provision to vary the position of the device if

required. The other end of the plate is fitted with a porcelain guide that feeds the core

filament at a precise position behind the front drafting roller. This device is fitted with a pre-

tensioner and is kept in a horizontal plane. Varying the number of tension discs may vary the

input tension of the core filament. The package containing the core filament material is

suspended from a bar such that they could rotate easily, thus avoiding any tendency to stretch

the filament before it is fed to the tensioning device. By adding two extra attachments

(filament creel and tensioner) in general ring frame, filament core yarn can be produced.

Fig 02: Core spun yarn production by ring frame

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3.2.2) Core spun yarn production by rotor spinning

Nield and Ali have developed a technique in rotor spinning machine to produce core spun

yarns. Twist efficiency and pre- tension of filament are the influencing factors in core spinning.

In order to increase the contact area between yarn arm and doffing tube (for increasing the

twist efficiency), a copper flange was soldered to the inner end of the doffing tube. The

doffing tube was mounted on a ball bearing, rotated by a separate drive opposite to the

rotation of the rotor with a speed ratio of 1:9. The rotating doffing tube inserts a false twist

and pushes twist back to the peel off point. The rotation of the rotor wraps the yarn arm

around the continuous filament core. A minimum pre- tension is necessary to avoid filament

flung out into the rotor collecting surface. The core is not twisted during the process, it is

economical to produce coarse core spun yarn through rotor machine than the ring core spun

yarn.

Fig 03: core spun yarn production by rotor spinning system

3.2.3) Core spun yarn production by friction spinning

In friction spinning system, the fibers are individually collected and twisted to form a yarn. A

wide range of staple length can be processed by this system. The deposition and twist of fibers

on to the yarn tail is to be replaced by a filament core to obtain full coverage of core. Wrap

spinning system is a frictional spinning process; a drafted ribbon of parallel fibers that

constitute the bulk of the spun yarn is wrapped by either surface fibers protruding from the

ribbon or by continuous filaments so as to impart coherence and strength to the resulting

yarn. It is believed that the core is false twisted by the rotation of the friction drums before

being wrapped by the sheath fiber. Strength of the core spun yarn have direct relationship

with the strength of core filaments and the number of sheath fibers that are active in

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generating radial pressure due to their structural helical configurations. The effectiveness of

wrapping of sheath fibers depends on the physical and mechanical characteristics of fibers,

configuration, length of variations and firmness of the wrap and wrap angle.

3.2.4) Core spun yarn production by MJS spinning system

It was reported that the Airjet spinning system could be used for producing core yarns after

optimizing process parameters. A relatively higher first nozzle pressure is advantageous for

improving sheath- slippage resistance. The use of higher spinning speed and wider condenser

markedly improves the tenacity, breaking extension, initial modulus and sheath slippage

resistance which affects the yarn hairiness, mass irregularity and flexural rigidity. However,

yarn properties deteriorate at high spinning speed especially for finer yarns. The schematic

diagram of MJS spinning system for the production of core spun yarn is shown below.

Fig 04: Core yarn production by friction

spinning

Fig 05: Schematic diagram of MJS spinning system

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3.3) THE PROCESS VARIABLES THAT AFFECT THE CORE SPUN

YARN PROPERTIES ARE:

Core sheath ratio

Pre- tension applied to the core material

Spinning draft

Number of roving draft

Twist

3.3.1) Core sheath ratio

It has been found that decreasing sheath content will increase the strength of the core spun

yarn. Apart from this there is an improvement in the extension and the evenness properties.

In the case of core spun sewing threads, a 2:1 core sheath ratio gives poor coverage and may

raise problems of stripping off the sheath during sewing, whereas, with a 1:1 core sheath

ratio, the striping off problem is reported to minimize.

3.3.2) Pre- tension to core material

The pretension is needed to regulate the geometrical position of the filament. This input

tension varies with the twist factor, size and quality of the filaments used. Balasubramaniam

furnished a method for optimizing the tension of the core filament in the core spinning

process. Colored filament was passed over a tension device of attachment and fed before the

nip of the front roller of ring frame. The pre- tension was gradually raised until the colored

filament is completely covered by the cotton fibers and this value was taken as the optimum

input tension. It was approximately 10% of the breaking load of the core yarn. An introduction

of a compensatory tensioner can be reducing the tension variation. An extension of 1% to the

core filaments while feeding to the ring frame ensures no buckling or curling of sheath fiber.

Core yarns are usually pre- tensioned to an extension of around 5-10% for flat continuous

filament yarns, about 30% for textured yarns and up to 400% for an electrometric core. If

insufficiently tensioned, the filament will either periodically appear at the yarn surface, grin

through or become wrapped around the fiber ribbon as the ribbon being twisted.

3.3.3) Spinning draft

Selection of appropriate draft of elastane filament for specific yarn linear densities are an important aspect of core-spun yarn manufacturing. The aim of this study was to further investigate the effects imposed by core draft.

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Spinning draft can be varied to obtain the required yarn count based on the core to sheath ratio. The drafts in core-spinning depend on the type, the decitex and the pre-stretch of spandex. The real, total draft (TD) of the spandex core in a spun yarn includes both the gear draft (GD, machine draft) and the winding pre-stretch of the spandex yarn on its tube. The draft of the spandex core in the spun yarn is always higher than the gear draft (GD) applied in the spinning frame.

The following table shows the optimum draft range for typical core spun yarn count range recommended by Rieter website according to practical experiences.

Table 01: Draft range recommendation by Rieter

The optimum output (spinning speed) of good core yarn cannot be reached by setting low

number of turns per meter and highest drafts. There is a limit to spindle speed for every draft

depending on the staple applied in the cover, yarn count and its twist factor. There are also

limits concerning the traveler speed. For better result the traveler speed should not exceed

26 m/sec in spinning with spandex with cotton. The choice of the highest draft for the

optimum production should also take into account the end use of the core-spun yarn and its

performance in the subsequent process of knitting or weaving and garment wear.

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3.3.4) Number of roving feed

The possible ways of feeding the core material at the front roller nip with respect to roving

are:

Filament at the center of the roving

Filament at the sides of the roving

Filament on the top of the roving.

Two roving feeding (filament at the center of the roving) provides better core positioning and

control during spinning influences the structure and properties of core spun yarns.

3.3.5) Twist

Adequate cohesion is obtained in individual yarns at high twist rates and it minimizes the

sheath slippage. In addition to this, the filament pre- twist in opposite direction to the ring

twist reduces the sheath slippage. The extension of the core spun yarn tends to reduce at

higher twist levels.

3.4) PROBLEMS ASSOCIATED WITH CORE SPINNING

One of the major problems of core spinning system in ring frame is the stripping off of sheath.

It is the slippage of core filament against sheath. Thus creating bad covering of core. This

happens when improper twist is applied, the pre-tension is not accurate or roving feed

position is not carefully handled. So to avoid stripping off, higher twist is applied and speed is

controlled. So reduced production is caused.

3.5) END USES

The outstanding quality characteristics of core yarns enabled them to be used in many items

of ladies’ and men’s outer and inner wear.

In addition to the improved wearing properties and comfort, better shape retention,

resistance to creasing and bagginess have caused them to be used extensively.

Conventional uses: Elastic core yarns have been used for many years primarily in lingerie and foundation garments, swimwear and hosiery, conveyer belt, sewing thread, socks, blanket as well as sportswear.

Burn out yarns: For high quality burn-out yarns, core yarns are processed in the first instance. The cellulose is “burnt-out” in the surface in a targeted fashion by the

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finisher during covering with thread. A stylish contrast of transparent and non-opaque materials results.

Technical Yarns: The yarns are temperature stable, extremly non-tear and strong

through the use of raw materials such as Preox, Twaron or Kevlar. In addition to their classical sectors of use technical yarns are increasingly used for Techno fabrics.

Sewing Thread: With Core yarns we set the best standards for the manufacture of sewing threads. The covering of the fibre protects the high tenacity Polyester filament core from the high temperatures which occur during sewing. As a result higher sewing speeds are achieved than with conventional sewing threads.

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CHAPTER: 04

WORK PLAN

19

4.1) MATERIAL

Our primary goal is to produce different counts of core spun yarn. For this purpose lycra and

cotton have been taken as raw materials for core filament and outer sheath respectively. The

used cotton had the property parameters as per the specifications below:

Table 02: Fiber parameters for yarn production

St. length UHML Str Elg Mic

1-7/16” Avg 35.10 37.6 6.9 3.72

1-1/8” Avg 29.63 32.6 6.7 3.72

The hanks of used cotton roving are as following:

Table 03: Hanks of cotton roving

Nominal

count

50Ne

(40D)cw

48Ne

(40D)cw

10Ne

(70D)kw

10Ne

(40D)kw

21Ne

(70D)cw

12Ne

(70D)cw

10Ne

(70D)cw

R.H Ne

1.25 1.25 0.7 0.7 0.7 0.7 0.7

Core forming filament lycra was used with two fineness variations of 70 denier and 40 denier.

Parameters for lycra are as follows:

Table 04: Lycra specifications

Filament Fineness Tenacity (g/den) Elongation % Strength (g)

Lycra 70Den 1.07 533 75.1

40den 1.27 478 51.1

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Thus, the two components are combined together to form the desired yarn for further testing

and effect verification. The produced yarn had the following parameters:

Table 05: Yarn parameters

Yarn count (Ne) TPI TM Lycra%

50 (40D) cw 33.00 4.6 9.41

48 (40D) cw 32.00 4.6 9.15

10 (70D) kw 20.00 5.0 3.81

10 (40D) kw 19.0 5.0 3.70

21 (70D) cw 21.50 4.6 6.93

12 (70D) cw 20.00 5.0 4.00

10 (70D) cw 18.0 5.0 3.90

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4.2) METHOD AND WORK DESCRIPTION

Various types of fibers such as cotton, lycra etc. were collected for the production of core

spun yarn.

The fibers were tested as per their staple lengths. As many as ten samples were used in

each case.

For the purpose of testing the fiber properties, the testing machines ‘Premier ART’ and

‘AFIS PRO’ were used. It is mentionable that the premier ART was used in HVI mode.

Cotton roving was collected from speed frame.

Then, ring spinning process was used to produce core spun yarn. It was based on the

principle that- ‘Filament is passed through the delivery roller exactly at a time when the

roving gets converted to the yarn form right after drafting.

Various machine settings (TPI, total draft, lycra draft, Z wheel etc.) were also altered to

produce various counts of yarn.

A total of seven count variations were produced. The fineness values have been included

in the previous table.

Then, certain properties of the produced yarn were tested. The tested properties

included Um (%), CVm (%), index, Thn/km (%), Thk/km (%), neps/km (%), and hairiness.

Premier tester 7000 was used for this purpose.

Tensile properties were also tested by the UNIVERSAL STRENGTH TESTER.

Then the results from the TESTER were taken and a study on the effects of core draft on

yarn properties was made.

All yarn tests were carried out after conditioning the specimens in a standard atmosphere (temperature 20 ± 2°C, 65 ± 2% relative humidity) for 24 h.

Finally, the studied results were used to produce a convenient and explanatory written

report.

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CHAPTER: 05

EXPERIMENTAL RESULTS

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5.1) FIBER PROPERTIES

At first premier ART was used to get the fiber properties. It was used in HVI mode. The average

values gathered were:

Table 06: Fiber properties as obtained from premier ART tester

St.

length

UHML ML UI Str Elg Mic Amt Rd +b CG MR SFI

1-

7/16”

Avg 35.10 29.36 83.7 37.6 6.9 3.72 1153 70.2 13.6 24-

1

0.84 3.9

1-1/8” Avg 29.63 24.43 82.5 32.6 6.7 3.72 1101 77.3 9.0 21-

4

0.82 8.3

Then, AFIS PRO was employed to gather rest of the specifications which include:

Table 07: Fiber properties as obtained from AFIS PRO tester

St.

lengt

h

Nep

cnt/

g

Nep

(um

)

SCN

Cnt

/g

SCN

(U

M)

L(w

)m

m

L(w

)%c

v

SFC

(w)

%<

12.

7

UQ

L(w

)

mm

L(n)

mm

L(n)

%cv

Fine

MTe

x

IFC

%

Mat

rati

o

1-

7/16”

Avg 123 645 5 141

0

29.

4

33.

1

5.5 36.

0

24.

1

47.

0

148 6.3 0.8

7

1-

1/8”

Avg 170 774 28 151

7

24.

0

37.

6

10.

3

29.

8

19.

1

50.

8

151 6.6 0.8

6

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5.2) YARN PROPERTIES

The results obtained from premier tester 7000 are:

Tested by: Premier Tester

Table 08: Yarn properties

Yarn count Um% CVm% CVm

1m%

CVm

3m%

Index Thn/km

(-40%)

Thn/km

(-50%)

Thn/km

(+35%)

50Ne(40D)cw 10.03 12.71 3.83 2.87 1.18 49 1 323

48Ne(40D)cw 10.55 13.33 4.01 3.21 1.51 56 1 334

10Ne(70D)kw 10.47 13.32 4.72 3.77 2.76 26 0 631

10Ne(40D)kw 10.50 13.77 4.91 3.99 2.94 28 0 646

21Ne(70D)cw 8.45 11.27 3.42 2.77 1.52 6 0 149

12Ne(70D)cw 1062 13.51 4.76 3.64 2.55 34 0 654

10Ne(70D)cw 10.11 13.01 4.54 3.39 2.50 21 0 627

Table 09: Yarn properties

Yarn count Thn/km

(+50%)

Thn/km

(+70%)

Neps/K

m

(+140%)

Neps/K

m

(+200%)

Neps/K

m

(+280%)

Neps/K

m

(+400%)

Rel.Cnt

%

Hairine

ss

50Ne(40D)c

w

31 7 242 56 16 4 100.0 3.86

25

48Ne(40D)c

w

38 8 261 62 19 7 100 4.21

10Ne(70D)k

w

96 10 299 28 4 1 100.0 7.06

10Ne(40D)k

w

89 13 301 31 7 2 100 7.87

21Ne(70D)c

w

19 7 83 20 7 3 100.0 5.00

12Ne(70D)c

w

97 6 457 55 5 0 100 6.67

10Ne(70D)c

w

91 8 289 23 3 1 100 6.88

5.2.1) Various Properties for different type core spun yarn count:

Table 10: Yarn properties

Nominal

count

Actual

count

R.H

Ne

T.P.I T.M Total

Draft

Lycra

Draft

Lycra % Z

Wheel

50Ne(40D)cw 48.35 1.25 33.00 4.6 45.60 3.85 9.41 20

48Ne(40D)cw 47.13 1.25 32.0 4.6 45.10 3.80 9.15 20

10Ne(70D)kw 9.92 0.7 20.00 5.0 29.30 3.33 3.81 24

10Ne(40D)kw 9.10 0.7 19.0 5.0 29.00 3.4 3.70 24

26

21Ne(70D)cw 20.44 0.7 21.50 4.6 34.60 4.00 6.93 20

12Ne(70D)cw 11.01 0.7 20.0 5.0 30.00 3.50 4.00 22

10Ne(70D)cw 9.20 0.7 18.00 5.0 32.00 3.40 3.90 22

5.2.2) According to universal strength tester

Yarn tensile strength test are done by according to following specification:

Standard-ASTM D2256 (250mm 20 sec)

1. Title : Tensile properties of yarn by the single-strand method.

2. Jaw separation : 250.00 mm

3. Pre-tention : 0 cN

4. Rate of extension : 150mm/min

5. Break detection : 80%

6. Maximum load : 100 N

7. Time to break : 20.0 s

Table 11: Results from universal strength tester

Yarn count Count

Tex

Max.

Force (N)

Tenacity(g/tex) Extension

(%)

Time to

Break (S)

Lycra %

50Ne(40D)cw 11.81 1.78 11.737 6.15 7.3 9.41

48Ne(40D)cw 12.30 1.36 11.2757 5.41 6.6 9.15

10Ne(70D)kw 59.05 6.99 12.0702 7.60 8.7 3.81

10Ne(40D)kw 59.05 6.50 11.2186 6.93 7.8 3.70

21Ne(70D)cw 28.11 3.72 13.4815 7.95 9.5 6.93

12Ne(70D)cw 49.21 7.13 14.7756 7.31 8.4 4.00

10Ne(70D)cw 59.05 7.99 13.7977 7.86 9.8 3.90

27

CHAPTER: 06

DISCUSSION

28

DISCUSSION

The obtained results have been discussed by separating the results on the basis of

i) Different yarn counts produced from same filament denier (counts of 50Ne, 48Ne

from 40D and 21Ne,12Ne, 10Ne from 70D filament) and

ii) Same yarn counts produced from different filament denier (counts of 10Ne from

40D, 70D filaments).

The graphs have been used to compare relationships in the clusters of

i) Total draft, lycra draft and lycra %

ii) Tenacity and lycra draft

iii) Elongation percentage and maximum force with lycra draft

iv) Um% and CVm% for lycra draft and

v) Lycra draft with hairiness.

29

6.1) COMPARISON AMONG DIFFERENT YARN COUNTS WITH SAME

FILAMENT COUNT

Fig 06: Bar diagram for total draft, lycra draft and lycra % against count

Fig 07: Bar diagram for total draft, lycra draft and lycra % against count

The above bar diagrams have been drawn for different yarn counts produced from the same

filament counts (40&70D). It is evident that the lycra draft is very closely varied. But total draft

has been varied enough to produce yarns of desired count.

45.6 45.1

3.85 3.8

9.41 9.15

0

5

10

15

20

25

30

35

40

45

50

50Ne(40D) 48Ne(40D)

Total draft

Lycra draft

Lycra%

34.6

3032

4 3.5 3.4

6.93

4 3.9

0

5

10

15

20

25

30

35

40

21Ne(70D) 12Ne(70D) 10Ne(70D)

Total draft

Lycra draft

Lycra%

30

Fig 08: bar diagram for tenacity and lycra draft against count

Fig 09: bar diagram for tenacity and lycra draft against count

Here, the bar diagrams for various values of tenacity along with lycra draft (fig- 08) clearly

reveals a direct relationship with drafting. As the drafting values increase, there is a higher

value for tenacity. Here in figure 09, 12Ne yarn has the highest tenacity. So it is better than

the others. Again, between two figures 08 & 09, coarser yarns have higher tenacity. Hence,

we can assume that a coarser yarn count gives high tenacity.

11.73711.2757

3.85 3.8

0

2

4

6

8

10

12

14

50Ne(40D) 48Ne(40D)

Tenacity (g/tex)

Lycra draft

13.4815

14.775613.7977

43.5 3.4

0

2

4

6

8

10

12

14

16

21Ne(70D) 12Ne(70D) 10Ne(70D)

Tenacity(g/tex)

Lycra draft

31

Fig 10: Bar representation of elongation percentage and maximum force with lycra draft.

Fig 11: Bar representation of elongation percentage and maximum force with lycra draft.

From figure, it is very much similar to the tenacity graphs. It is evident that the higher draft

values are associated with the higher percentage of elongation at break and vice versa.

Similarly, the maximum load experienced is also high thus giving better strength. But an

optimum draft is required for a better performance which is obtained for 12Ne yarn here (fig-

11).

1.78

1.36

6.15

5.41

3.85

3.8

0 1 2 3 4 5 6 7

50Ne(40D)

48Ne(40D)

Lycra draft

Elongation%

Maximum force(N)

3.72

7.13

7.99

7.95

7.31

7.86

4

3.5

3.4

0 1 2 3 4 5 6 7 8 9

21Ne(70D)

12Ne(70D)

10Ne(70D)

Lycra draft

Elongation%

Maximum force(N)

32

Fig 12: bar representation of Um% and CVm% for lycra draft

Fig 13: bar representation of Um% and CVm% for lycra draft

From figures 12&13, we see that the co-efficient of mass variation reduced with increased draft value.

The unevenness percentage also shows similar tendency. Here we see that the 21Ne yarn has the best

possible value. So in terms of mass variation, it stands out as the best.

12.71

13.33

10.03

10.55

3.85

3.8

0 2 4 6 8 10 12 14

50Ne(40D)

48Ne(40D)

Lycra draft

Um%

CVm%

11.27

13.51

13.01

8.45

10.62

10.11

4

3.5

3.4

0 2 4 6 8 10 12 14 16

21Ne(70D)

12Ne(70D)

10Ne(70D)

Lycra draft

Um%

CVm%

33

Fig 14: effect of lycra draft on hairiness

Fig 15: effect of lycra draft on hairiness

Increase of draft caused reduction in hairiness. Coarser yarns have more hairiness than the finer ones.

As per hairiness value 50Ne yarn is better than the others.

3.86

4.21

3.85

3.8

3.5 3.6 3.7 3.8 3.9 4 4.1 4.2 4.3

50Ne(40D)

48Ne(40D)

Lycra draft

Hairiness

5

6.67

6.88

4

3.5

3.4

0 1 2 3 4 5 6 7 8

21Ne(70D)

12Ne(70D)

10Ne(70D)

Lycra draft

Hairiness

34

6.2) COMPARISON BETWEEN SAME YARN COUNTS WITH

DIFFERENT FILAMENT COUNT

Fig 16: Bar diagram for total draft, lycra draft and lycra % against denier value

Fig 17: Bar diagram for tenacity with lycra draft.

From figure 17, 70D filament needed lesser draft than 40D one. But its tenacity is better than the

40D filament yarn. So we can say that coarser yarns have better tenacity.

29.3 29

3.33 3.43.81 3.7

0

5

10

15

20

25

30

35

10Ne(70D) 10Ne(40D)

Total draft

Lycra draft

Lycra%

12.070211.2186

3.33 3.4

0

2

4

6

8

10

12

14

10Ne(70D) 10Ne(40D)

Tenacity

Lycra draft

35

Fig 18: Representation of elongation percentage and maximum force with lycra draft.

Here, the graph shows higher elongation and force at break for 70D yarn. So, less draft for

coarser yarn has high elongation and force absorption.

Fig 19: bar representation of Um% and CVm% for lycra draft

For same yarn count, we can see that there is no significant change in mass variation and

unevenness for changing draft. So this is negligible and we can assume that there was no

effect.

6.99

6.5

7.6

6.93

3.33

3.4

0 1 2 3 4 5 6 7 8

10Ne(70D)

10Ne(40D)

Lycra draft

Elongation%

Maximum force

13.32

13.77

10.47

10.5

3.33

3.4

0 2 4 6 8 10 12 14 16

10Ne(70D)

10Ne(40D)

Lycra draft

Um%

CVm%

36

Fig 20: effect of lycra draft on hairiness

Here, we see a small degree of change in hairiness. However, the yarn count being low, the

values are much higher. So coarse yarn has more hairiness.

7.06

7.87

3.33

3.4

0 1 2 3 4 5 6 7 8 9

10Ne(70D)

10Ne(40D)

Lycra draft

Hairiness

37

6.3) INFERENCE

Analyzing the available data, we see that, presence of filament in 50cw has better result in

hairiness, 10kw has good U%, CV% and hairiness. 12 Ne yarn has the good extension%,

tenacity than 21 cw and 10 cw.

From the previous discussions, we realize that the effect of core draft on yarn properties is

prominent. Draft is needed to be balanced and an optimum one is used for relative denier

value. Hairiness, imperfections, neps etc. reduce when higher draft is used. The technical

qualities of yarn are affected by draft as well. Tenacity, elongation at break, maximum load

etc. have been found to be more enduring when draft was less and coarse yarn was produced.

The compatibility of the overall yarn Drafting and the lycra draft used in the core is very important for obtaining the optimum yarn tenacity and the elongation percentage. Moreover, the yarn tenacity and elongation percentage cannot be improved by simply increasing the core draft. There is a draft limit beyond which the trend may be reversed for core of a particular draft. It was further concluded that the lycra draft has statistically significant effect on yarn tenacity, elongation and hairiness.

38

CHAPTER: 07

CONCLUSION

39

CONCLUSION

The project work we completed circled around the study of effects induced in a core spun

yarn due to core draft. We tested the samples for comparison of certain properties which

included tenacity, maximum force at break, elongation percentage, hairiness and mass

variation.

We concluded that the core draft has a direct relationship with yarn quality especially

regarding the technical aspects. We found that higher core draft to an optimum level gives

better testing performance which is the main purpose of producing core spun yarn.

Development of core spun yarn has broadened the scope of higher and better involvement

of textile end products to technological uses with increased and efficient performance. It has

eased the possibility of incorporating parametric requirements with aesthetic ones in the

same product for goal oriented end uses. So studying the effects of core draft on core spun

yarn has enabled us to shed some light on how it is obtained.

40

REFERENCE

Fundamentals of Spun Yarn Technology, Carl A. Lawrence, Ph. D www.fiber2fashion.com/industry-article/textile-industry-

articles/production-and-properties-of-core-spun-yarns www.rieter.com/en/spun-yarn-systems/parts-

conversions/technology-parts http://omicsgroup.org/journals/rheological-modeling-of-the-

dorlastan-core-spun-yarns www.autexrj.com/cms/zalaczone_pliki/3.pdf www.textileglossary.com/terms/core-spun-yarn