study the causes of yarn breakage and possible

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Leather Engineering Thesis and Dissertations

2017-12

STUDY THE CAUSES OF YARN

BREAKAGE AND POSSIBLE

METHODS FOR ITS REDUCTION IN

WEAVING AT BDTSC

BITEW, NIGUSSIE

http://hdl.handle.net/123456789/8234

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STUDY THE CAUSES OF YARN BREAKAGE AND

POSSIBLE METHODS FOR ITS REDUCTION IN WEAVING

AT BDTSC

NIGUSSIE BITEW

ETHIOPIAN INSTITUTE OF TEXTILE AND FASHION

TECHNOLOGY

BAHIR DAR UNIVERSITY

BAHIR DAR

2017

STUDY THE CAUSES OF YARN BREAKAGE AND

POSSIBLE METHODS FOR ITS REDUCTION IN

WEAVING AT BDTSC

BY

NIGUSSIE BITEW

A Thesis Submitted to the

Ethiopian Institute of Textile and Fashion Technology

In Partial Fulfillment of the Requirements for the Degree of

Master of Science

In

Textile Manufacturing

Under the Supervision of

Asst. Prof. Addisu Ferede

Ethiopian Institute of Textile and Fashion Technology

Bahir Dar University

Bahir Dar

JUNE, 2017

ii

Abstract

Yarn breakages have a great effect on weaving productivity and also on fabric

quality. The most important factors affecting the air jet weaving machine‟s

efficiency are warp and weft breaks which are strongly connected to the yarn

parameters. It was determined that the yarn properties, which mostly affect the

rates of both warp and weft breaks are yarn strength, yarn imperfections (thin

places, thick places, neps), yarn twist, yarn hairiness and unevenness.

The main causes of both weft and warp yarn breakages in weaving are poor yarn

quality, excessive loom speed, uncontrolled room temperature and relative

humidity, uncontrolled warp tension, mechanical problems of the machine, and

Other causes can be due to bad knots on warp yarn, poor size pick-up, loose

ends, fly stuck onto threads, snarls after weft pre feeder, snarls on cone,

improper cone forming, slough off at cone, wrong drawing–in, damaged back rest

roller, healed frames, drop wires and improper warp beam forming. The

breakage study was conducted using air jet looms at BDTSC. When weaving for

a period of one hour at a loom speed of 600 rpm, using a reed width of 1.6 m,

and producing a plain fabric with 24 ends/cm and 18 picks per centimeter

number of warp and weft breaks for 100% cotton yarn. Minitab 15 software was

used for analyzing the experimental data. Analysis of Variance (ANOVA) was

used to detect the significant effects of these variables. The breakage rate of

unconditioned yarn is greater than conditioned yarn. Since conditioning improves

yarn qualities (like; strength, elongation, etc.).

iii

Approval page

I certify that I have supervised /read this study and that in my opinion it conforms

to acceptable standards of scholarly presentation and is fully adequate, in quality

and scope, as a thesis for the fulfillment of the requirements for the degree of

Master of Science in Textile Manufacturing.

_________________ Signature _________________

Supervisor co -supervisor

___________________ _________________

External Examiner 1 External Examiner 2

___________________ _________________

Internal Examiner Chairman Examination committee member

This thesis was submitted to the Ethiopian Institute of Textile and Fashion

Technology, Bahir Dar University and is accepted as fulfillment of the

requirements for the Degree of Master of Science in Textile Manufacturing.

_________________ ___________________

Scientific Director/ Director/

Head of the program Dean of postgraduate students

iv

Declaration

I hereby declare that the thesis is submitted in fulfillment of the Master degree is

in my own work and that all contributions from any other persons or sources are

properly and duly cited. I further declare that the material has not been submitted

either in whole or in part, for a degree that at this or any other university. In

making this declaration, I understand and acknowledge any breaches in this

declaration constitute academic misconduct, which may result in my expulsion

from the program and/or exclusion from the award of the degree.

Nigussie Bitew _______________

Name of Candidate Signature of candidate Date

v

Copy right by

© Nigussie Bitew and EiTEX, 2017

vi

Acknowledgments

I would like to thank the almighty God for giving me the strength to end this thesis

work. Next to God I thank my advisor asst. professor Addisu Ferede (Scientific

director of EiTEX) for his cooperation and reliable guidance from start to the final.

Also; I would like to thank all the people who helped me during this thesis work. I

found very joyful experiences which are very helpful for my dreams I am intended

to be. Unfortunately, there were many challenges to be tacked as well, and many

people were there with me. It is my pleasure to express my appreciation to all of

them for standing in my side. My appreciation also goes to Bahir Dar Textile

Share Company for allowing me to do my thesis in the factory and to use testing

laboratory.

vii

Advisors’ Approval Sheet

ETHIOPIAN INSTITUTE OF TEXTILE AND FASHION TECHNOLOGY (EiTEX)

POSTGRADUATE OFFICE

This is to certify that the thesis entitled “study the causes of yarn breakage and

possible methods for its reduction in weaving at BDTSC” submitted in partial

fulfillment of the requirements for the degree of master‟s with specialization in

Textile Manufacturing, the Graduate program of the Ethiopian Institute of Textile

and Fashion Technology, and has been carried out by Nigussie Bitew, ID No.

MTM/R/006/08 under my supervision. Therefore, I recommend that the student

has fulfilled the requirements and hence hereby can submit the thesis to the

institute.

Asst. prof. Addisu Ferede ____________ ___________

Name of advisor Signature Date

viii

Board Examiner’s Approval

ETHIOPIAN INSTITUTE OF TEXTILE AND FASHION TECHNOLOGY (EiTEX)

POSTGRADUATE OFFICE

We, the undersigned, members of the Board of the final open defense by have

read and evaluated his/her thesis entitled “study the causes of yarn breakage

and possible methods for its reduction in weaving at BDTSC”, and examined the

candidate. This is, therefore, to certify that the thesis has been accepted in partial

fulfillment of the requirements for the degree of Master of Science in Textile

Manufacturing.

________________ ____________ _______________

Name of the Chairperson Signature Date

________________ ____________ _______________

Name of Internal Examiner Signature Date

________________ ____________ _______________

Name of External Examiner Signature Date

________________ ____________ _______________

PG/Graduated committee Signature Date

Final approval and acceptance of the thesis is contingent upon submission of the

final copy of the thesis to the post graduate studies office through the institute

Graduate committee of the candidate‟s program.

Stamp of postgraduate office

Date: _________________

ix

Table of Contents

Abstract ............................................................................................. ii

Acknowledgments ............................................................................. vi

List of Tables ................................................................................... xii

List of Figures .................................................................................. xiii

List of Symbols and Abbreviations .................................................. xiv

CHAPTER ONE ................................................................................. 1

INTRODUCTION ............................................................................... 1

1.1 Prefaces on fabric production ...................................................................... 1

1.2 Background ................................................................................................. 2

1.3 Problem statement ...................................................................................... 4

1.4 Objective ..................................................................................................... 4

1.4.1 General objective ........................................................................................................ 4

1.4.2 Specific objectives ....................................................................................................... 4

1.5 Scope .......................................................................................................... 5

CHAPTER TWO ................................................................................ 6

LITERATURE REVIEW ..................................................................... 6

2.1 Yarn breaks in air jet weaving machine ....................................................... 6

x

2.2 Relationship between yarn strength, elongation and breakage ................... 8

2.3 Yarn breaks due to yarn imperfections ........................................................ 9

2.4 Effect of yarn twist on yarn breakage ........................................................ 11

2.5 Effect of yarn hairiness on yarn breakage ................................................. 11

2.6 Effect of sizing on yarn breakage .............................................................. 12

2.7 Effects of weaving conditions on yarn breakage ....................................... 15

CHAPTER THREE .......................................................................... 17

METHODOLOGY ............................................................................ 17

3.1 Materials .................................................................................................... 17

3.2 Methods .................................................................................................... 17

3.2.1 Evaluation of yarn quality (using ATSM standards) ............................................. 18

3.2.2 Study of both warp and weft yarn breakage ......................................................... 20

3.2.3 Observations .............................................................................................................. 21

3.2.4 Data analysis.............................................................................................................. 21

RESULT AND DISCUSSION ........................................................... 22

4.1 Effect of yarn conditioning on breakage .................................................... 22

4.2 Effect of hairiness and imperfection on yarn breakage .............................. 27

4.3 Effect of twist on yarn breakage ................................................................ 30

xi

4.4 Effect of sized yarn tenacity and elongation on yarn breakage ................ 32

4.5 Determination of yarn breakages .............................................................. 35

4.6 Causes of yarn breakages and solutions .................................................. 39

CHAPTER FIVE............................................................................... 42

CONCLUSION AND RECOMMENDATION ..................................... 42

5.1 Conclusion ................................................................................................ 42

5.2 Recommendation ...................................................................................... 43

5. APPENDICES.............................................................................. 49

Appendices 1 .................................................................................................. 49

Appendices 2 .................................................................................................. 50

Appendices 3 .................................................................................................. 51

xii

List of Tables

Table 2.1 the size recipes used in four sizing units with different level of hairiness

reduction during sizing are provided……………………….............................14

Table 4.1 determination of unconditioned yarn tenacity and elongation ……….22

Table 4.2 ANOVA analysis of unconditioned yarn tenacity and elongation……..23

Table 4.3 determination of conditioned weft yarn………………………………….25

Table 4.4 ANOVA analysis of conditioned yarn…………………………………….25

Table 4.5 comparison of conditioned and unconditioned yarn properties………26

Table4.6 determination of yarn imperfection and hairiness…………….…………27

Table 4.7 ANOVA analysis of yarn hairiness and imperfection…………………..30

Table 4.8 determination of yarn twist……………………………………………......30

Table 4.9 ANOVA analysis of yarn twist…………………………………………….31

Table 4.10 determination of sized yarn elongation and tenacity………………....32

Table 4.11 ANOVA analysis of sized yarn tenacity and elongation……………...33

Table 4.12 comparison of unsized and sized yarn properties…………………….34

Table 4.13 determination of unconditionedyarn breakages……………………....35

Table 4.14 ANOVA analysis of unconditioned yarn breakages……………….….37

Table 4.15 determination of conditioning yarn breakages………...………………36

Table 4.16 ANOVA analysis of conditioned warp and weft yarn breakages........37

Table 4.17 comparison of unconditioned and conditioned yarn breakages……..37

xiii

List of Figures

Figure 2.1 different imperfection in a spun yarn………………………………....…10

Figure 3.1 uster tensorapidYarn imperfections,and hairiness…………………....18

Figure 3.2 uster tester-5………………………………………………………………19

Figure 3.3 air jet weaving machine………………………………………….............21

Figure 4.1 unconditioned yarn tenacity and elongation…………………………...23

Figure 4.2 conditioned and unconditioned yarn tenacity and elongation……..…26

Figure 4.3 yarn imperfection and hairiness……………………………………..…..29

Figure 4.4 yarn twist factor and twist per meter…………………………..………..31

Figure 4.5 comparison of sized and unsized yarn elongation and tenacity……..34

Figure 4.6 comparison of unconditioned and conditioned yarn breakages……..37

xiv

List of Symbols and Abbreviations

BDTSC – Bahir Dar textile share company

TPM – Twist per meter

TPI – Twist per inch

TF – Twist factor

B-force – Breaking force

hr – hour

m – meter

M/C – Machine

RPM – Revolution per minute

ASTM – American society for testing and materials

CV – Coefficient of variation

CVm% – Coefficient variation of mass

USP – Uster statistics percentage

CN – Centi- Newton

CMPX – 10000 picks

Min – minute

mpm – Meter per minute

ppc – picks per centimeter

xv

OE – open end

RH – Relative humidity

U% - Uster un evenness

SH – Standard deviation of hairiness

R.H – Right hand

L.H – Left hand

PVA – poly vinyl alcohol

mm – millimeter

1

CHAPTER ONE

INTRODUCTION

1.1 Prefaces on fabric production

Modern weaving machines stand out as an expensive class compared to

conventional machines in terms of capital investment. This basic difference

requires certain prerequisites to be considered while planning to venture into

modern weaving machines. The quality of yarn used on shuttleless looms is the

prime criteria considered for quality weaving. The machine parameters to be

controlled for an optimized preparatory operation have been dealt with respect to

winding, warping and sizing operations. Guidelines for machine stoppages

corresponding to warp and weft breakages in weaving are considered as

important in deciding the efficiency of a shuttleless weaving shed. For the

successful installation of shuttleless looms, it becomes inevitable to go for quality

yarn and optimization of the preparatory operations prior to weaving. A better

quality yarn leads to a quality warp and sized beam which consequentially gives

and efficient weaving operation both qualitatively and quantitatively.

2

1.2 Background

The efficiency of weaving is the most critical factor that has to be considered in

terms of productivity. The productivity of the loom is mainly decided by the speed

of the machine as well as the down time of the machine. In weaving, unwanted

loom stoppages always occur which leading to low production rates. Loom

stoppages during the weaving process usually occurs due to warp breaks, weft

breaks, mechanical breakdown, electrical faults, beam gaiting, shortage of spare

parts, power interruption, beam changing, cleaning, oiling and lubricating. Among

these warp and weft breaks, and beam gaiting occur more frequently than the

rest.

In rapier and air jet looms, warp and weft breaks causing loom stoppages during

weaving, are more frequent when using 100% cotton yarn. Improper adjusted

machine parameters and weaving conditions lead to yarn breaks during weaving.

For instance, both warp and weft breaks can be a result of uncontrolled room

temperature and relative humidity, poor quality of yarn, excessive loom speed,

and uncontrolled warp tension. Other causes can be due to knots on warp yarn,

poor size pick-up, loose ends, fly stuck onto threads and abrasive effect of the

drop wires and the heddles. Warp breaks cause longer stoppages as compared

to weft breaks since they require more time for repair particularly when using

100% cotton yarn.

3

In weaving industry reduction of yarn breakage is always emphasized to increase

productivity and maintain quality of woven fabric. In order to reduce the

production costs per meter of woven fabric, the yarn breakage are essential to be

reduced at every stage of manufacturing the woven fabric. In weaving industry

one of the most critical problems are breakage of both warp and weft yarns which

not only reduce the production rate and also deteriorate the quality of produced

fabric. These breakages produce lots of problems on the preparatory processes

and on loom. So by reducing these breakages of both warp and weft yarns not

only increase productivity of the processes involved to the production of fabrics

including warping, sizing, etc. and maintain quality of the woven fabric can be

increased and also reduces wastages of yarn.

In order to reduce yarn breakage, increase productivity of both machines and

labor also the quality of the produced fabric it is essential to select the

appropriate yarn for the production of fabric. The selected yarn should meet the

predefined standards of yarn strength, yarn hairiness, yarn imperfections (thin,

thick places and neps), twist per inch (TPI), yarn elongation and the most

important factors. The yarn should be composed of good raw material like cotton

of good staple length, maturity, fineness etc. There are different standards for

different counts of ring spun yarns (carded/combed) which are given below. For

each yarn count there are different standard values of factors. For example yarn

strength, twist per meter, elongation, hairiness, thin places, thick places and

neps. During selection of yarn the following properties are needed to consider in

4

order reducing breakages of yarns. These are single yarn strength, lea strength,

elongation, hairiness and yarn imperfection (thin, thick places and neps).

1.3 problem statement

The production efficiency is basically depending on the weft and warp breakage

rates and the time taken to restore and restart the loom. Currently the most

critical problem at Bahir Dar Textile Share Company in weaving section is

breakage of both warp and weft yarns which reduce the production rate and

quality of produced fabric; especially weft yarn breakages. These breakages on

the preparatory processes and on the loom produce lots of problems. For

example; snarls, double picks and miss picks, etc.

1.4 Objective

1.4.1 General objective

The general objective of this thesis is to design the possible methods to reduce

the yarn breakage rates after investigating the causes and effects of warp and

weft yarn breakages during weaving process.

1.4.2 Specific objectives

Evaluate the quality of warp and weft yarns

Study the warp and weft breakage rate

Investigate the reasons for warp and weft yarns breakages

Study the effect of warp and weft yarn breakages on loom efficiency and

quality of woven fabrics

Design a feasible solutions to minimize the warp and weft yarns breakage

5

1.5 Scope

Ensure that the yarn coming from spinning must have the suitable characteristics

of strength, hairiness, thick places, thin places, neps, and elongation according to

the standard. Identify factors which causes and influence the yarn breakages

also the practical step and other possible methods needed to reduce the

breakage of both warp and weft yarns on the loom.

6

CHAPTER TWO

LITERATURE REVIEW

2.1 Yarn breaks in air jet weaving machine

In the case of using 100% cotton yarn in air jet machines, warp and weft breaks

causes machine stoppages during weaving. In addition, wrongly adjusted

machine parameters and weaving conditions lead to yarn breaks during weaving.

The tension of warp and weft yarns leads to high warp and weft breaks rate too.

In many research works, low warp tension of 50cN had a significant effect on

weft breaks due to the disturbance of the smooth passage of weft yarn across

the shed. Increasing warp tension to 70 cN weft breaks were stabilized. Higher

tensions (80 cN, 85 cN and 90 cN) in the warp did not have an effect on the weft

break. This is in contrast with the warp breaks that occur more when the tension

was over 70cN so at this tension the warp suffers longitudinal stresses while the

weft, not as strained as the warp (Nkiwane L, Marashe S., 2012).

Low yarn tension creates a clinging effect, resulting in yarn breaks for both warp

and weft. The values of peak tension may reach about 30% of the tensile

strength of yarn. Selection of high quality yarn to weave on high speed air jet

machines needs to choose high quality yarn to weave on high speed air jet

machines, it is to increase the efficiency and reduced yarn breaks (El-Messiry M,

Mito A., October, 1994).

7

Yarns spun from staple fibers are irregular. As very thin place occurs, it may fail

under the balloon tension in spinning and a spinning break occurs. When such a

very thin place survives spinning in a weavable singles yarn, it causes yarn

breaks in weaving. The magnitude and frequency of very thin places depend on

the number of fibers in the yarn crosses section, and the variability of fiber

diameter (James L., June 2005).

It was observed during weaving with maximum weft densities that the machine

stopped mainly due to weft stops. In the majority of machine stoppages, weft

yarn got entangled with warp yarns especially at the selvage regions. The cloth-

fell moved backwards with increasing weft density and decreased the front shed

size. However, the cloth-fell position moved backwards more at the selvages due

to the lower warp tension. This decreased shed openness at the selvages even

more and warp yarns got into the profile of the reed before the completion of weft

insertion, this was observed as the main reason causing weft stops very often

and limited the maximum weavable weft density (Yildiray T, Recep E., Nov.

2011).

The predictability of the warp breakage rate from a sizing yarn quality index using

a feed forward back propagation network in an artificial neural network system

was investigated. A good correlation between predicted and actual warp

breakage rates indicated that the warp breakage rates can be predicted by

neural networks (Shaimaa Youssef El-Tarfawy, 2016).

8

The yarn breakages on the air jet machine are due to:

1. Machine parameters: machine speed, machine width, main nozzle

pressure, sub nozzle pressure, reed design, and weft insertion time.

2. Yarn physical properties: yarn structure, yarn morphology, yarn air drag

coefficient, yarn diameter, yarn cross section shape, and diameter variability

along the weft length in the shed (thin places, thick places and neps).

3. Yarn mechanical properties: yarn strength, yarn elongation, yarn modulus

of elasticity.

The above analysis shows the complexity of the relation between wefts breaks

rate and yarn properties, in spite of the low value of the tension on the weft yarn

during insertion but yarn breaks occurs. This may be due to the effect of air

streams interaction with the yarn during insertion along the machine width. The

interpretation of the weft breaking rate for each yarn before weaving will help the

weaver to choose the machine settings. In this work the prediction of the weft

breaking rate has been made using Artificial Neural Network system (Shaimaa

Youssef El-Tarfawy, 2016).

2.2 Relationship between yarn strength, elongation and breakage

Strength of yarn is one of the most important factor which influence yarn

breakages (Jeon B.S. 2000). The yarn should have good strength otherwise it

will affect the efficiency of machine and quality of the fabrics. CV% of yarn

strength influences warp stoppages more than any other factor. Higher the single

yarn strength lesser will be the yarn breakages. Single yarn strength variability

9

should not exceed 8% and variability of single yarn twist should not exceed 6% if

optimum performance is required (Basu, A. 2006 and Booth, 2012).

The elongation depends upon the length of the fiber and also on T.P.I. different

yarns have individual values of elongation. For instance cotton has elongation of

6-7% which gives good power to the yarn against breakages. The elongation of

yarn play part in each of the preparatory process e.g. cone winding, warping,

sizing and weaving on loom (Booth, 2012, & Basu, A., 2006).

2.3 Yarn breaks due to yarn imperfections

A yarn with more imperfections will exhibit poor appearance grade, lower

strength and poor performance in weaving is likely to produce fabric with low

quality. More yarn imperfection causes higher yarn breakages during weaving.

Studies indicated that the size of thick places and neps were poorly correlated to

their mass. The thin places were reported to be positively correlated with their

size.

An analysis of thick places in carded yarns revealed that more than 75% of the

imperfections were due to the presence of fiber clusters and fiber clusters with

foreign matter (J. Ochola, J. Kisato, L. Kinuthia, J. Mwasiagi and A. Waithaka,

2012).

10

Figure2.1 different imperfection in a spun yarn

A yarn with poor evenness will have thick and thin places along yarn length,

while an even yarn will have little variation in mass or diameter along length and

these leads yarn breakage during weaving (Bona, M. 1994). Irregular yarns and

high imperfection levels in the yarn are the causes behind an uneven fabric

appearance and to some extent, the mass variation of fabric. In order to run a

weaving machine smoothly the yarn should be of uniform diameter though out its

lengths. With the use of even yarn the efficiency in Weaving will be improved

leading to higher productivity because of the lower incidence of weak places.

Fewer end breaks are encountered with regular (more even) yarns (Ravikeerthi.

Rao2014). An irregular yarn will also vary in strength along the yarn. More

regular the yarn better will be the appearance and aesthetic value of the product

(J. Ochola, J. Kisato, L. Kinuthia, J. Mwasiagi and A. Waithaka, 2012).

11

2.4 Effect of yarn twist on yarn breakage

Morton investigated that the spun yarns with higher twist multiplier exhibit greater

yarn irregularity (40-70%) which causes breakage in weaving (Morton, W.E.J.,

2003).

Gulati, ET.al (Gulati, A.N., and Turner, A.J., 2003) also worked out on the

relationship between diameter, twist, and count. They found that turns per inch in

any cross section are approximately inversely proportional to the number of

fibers in that part. A close relationship is also exhibited between fiber fracture and

yarn strength, about 60% of the fibers break when the yarn strength is at its

highest.

Barella discusses the influence of twist on yarn diameter, density, and

contracture, and has verified experimentally the theoretical relationship between

these parameters. The deformation and residual strain of individual fibers in

terms of yarn count and twist factor, fiber tension, lateral compression is

dependent upon the nature of fibers in the staple yarn. For getting better yarn

strength and torque understanding of twist distribution is very important factor

(Barella, A., 2003).

2.5 Effect of yarn hairiness on yarn breakage

The yarns with minimum hairiness have low yarn breakage and quality of the

fabric is also good. So during selection of yarn this factor should be considered

and hairiness of the yarn should be tested on the hairiness determining

12

apparatus, so breakages may control and quality of the end product may

consistent. Yarn unevenness affects fabric appearance and should preferably be

around 12% - 15%, U% depending on whether we are using combed yarn or

carded yarn. Doubled yarns should have significantly lesser U% and lesser

number of yarn defects (Basu, A., 2006. & Basal, G. & Oxenham, W. (2006).

2.6 Effect of sizing on yarn breakage

The loom shed efficiency entirely responsible for determination of performance of

any textile mill and that is depends on the practices required for preparation of

sizing beams. During sizing the stretch in the wet & drying zone are totally

responsible for loss in elongation which causes more breaks in weaving. If it is

not properly controlled in sizing this parameter will considerably result in to

reduction in yarn strength. It can be overcome by maintaining no stretch or

negative stretch in wet zone, this stretching zone is lies between saw box zone &

first drying cylinder. If the stretch in the zone does not control properly it will

considerably increase the warp breaks at loom, it will ultimately result to reduce

loom performance (B. C. Goswami, R. Anandjiwala and D. M. Hall, Marcel

Dekker, 2004).

Sizing not only provides strength to the yarn but also increase abrasion

resistance and increases the weaveability of the yarn. Proper sizing practices

reduce end breakages at loom which ultimately increases loom performance.

There are various sizing parameters which are responsible for maintaining quality

13

of size beam. The machine speed, squeezing roller pressure, viscosity of size

paste, temperature of saw box and stretch control are the essential parameters

which need to be control during sizing. A size yarn must have good abrasion

resistance which clearly reflects by its increase tensile strength with minimum

loss of elasticity and required amount of moisture for looming. Weavers beam

should not have more number of missing ends, cross ends, lappers and taped

ends so that it could unwind smoothly in weaving machine. To increase the

strength in abrasion resistance of yarn after sizing depend on a number of factor,

namely the recipe of the size mixing (Dr. Arindam Basu, June 2002).

Optimum yarn tension during sizing

Lappers during sizing vary between 0.2 per 1000 ends per 1000m and 1 per

1000 ends per 1000m in the sizing units studied, under good working conditions,

incidence of lappers during sizing needs to be maintained below 0.2per

1000ends per 1000 m. In general, when the sizing lappers are more, the

corresponding yarn has higher loss in elongation (B. C. Goswami, R.

Anandjiwala and D. M. Hall, Marcel Dekker, 2004).

14

The hairiness reduction during sizing varies between 25 and 80% in different

sizing units. In sizing units where the hairiness reduction is of a higher order, they

generally employ higher proportion of PVA as the film former in the size mix. Now

even for 100% cotton yarns PVA as a sizing ingredient is being increasingly used

particularly for yarns meant for shuttleless looms, where weft insertion rate is of a

higher order. The PVA coating is strong, abrasion resistant and can easily be

desized in hot water. Its strength is greater than standard starch and it is also

more flexible (Dr. Arindam Basu, June, 2002, & B. C. Goswami, R. Anandjiwala

and D. M. Hall, Marcel Dekker, 2004).

Table2.1 the size recipes used in four sizing units with different level of hairiness

reduction during sizing are provided

Sizing unit Count of

warp(Ne) Type of loom

% reduction

in yarn

hairiness after

sizing

Sizing

ingredients of

the size mix

% size

pick up

1 50s Projectile 70.10

PVA 23%

Starch 69%

Lubricants 8%

15

2 50s Air jet 70.34

PVA 23%

Starch 69%

Lubricants 8%

18

3 60s Projectile 52.08

PVA 6%

Starch 87%

Lubricants 7%

15

4 60s Air jet 44.49

PVA 12%

Starch 82%

Lubricants 6%

18

15

In units 1 and 2 where hairiness reduction is of the order of 70% the size recipe

has PVA at 23%. On the other hand in units 3 and 4 where hairiness reduction is

around 50% the size recipe has relatively lower concentration of PVA at 6 to

12%. Among the weaving units surveyed, some have achieved breakage rate

close to the guideline values recommended in this.

2.7 Effects of weaving conditions on yarn breakage

In textile production processes, there are more stringent requirements of

temperature, and humidity levels required for cotton weaving. For any process,

temperature cannot be less than 20℃ and not more than 31℃, and relative

humidity should not vary excessively, thus the only acceptable variation can only

be ± 5%, based on the Zig Bee 802.15.4 protocol technology (ShiFen J. and

GuiXiong L.). Weaving conditions for100% cotton fabric are designed to maintain

high relative humidity (RH) of 80% to 85% at the warp sheet level i.e. at 'loom

sphere' as high humidity helps to increase the abrasion resistance of the warp.

Whereas it would be suffice to maintain general humidity condition in the room at

around 65%of R.H (Roy M. M, Jan-Mar, 2005).

Relative humidity may be reduced to 65% or even lower if desired to provide

more comfortable working conditions and reduce maintenance costs on loom

parts that are sensitive to humidity (Wilmington, Delaware, 1998). Warner states

that the strength of cotton yarn increases as it is exposed to moisture e.g. 75%

relative humidity. A further increase in relative humidity will not increase the

strength of the fibers.

16

Masudur measured and analyzed how temperature and relative humidity affect

the efficiency of looms for cotton weaving. He concluded that, the highest

efficiency was obtained at 65% relative humidity and 27℃ temperature, which are

in agreement with the international standards for cotton weaving in European

countries (Masudur R. and Md RuhulA, June, 2011).

17

CHAPTER THREE

METHODOLOGY

3.1 Materials

There are different materials and equipment will be used for this study. Some of

are:

20Ne 100% cotton grey weft and warp yarn

20Ne 100% cotton sized warp yarn

20Ne 100% cotton condition weft yarn

Uster Tensorapid 4

Electrical twist tester

Evenness tester and uster tester-5

3.2 Methods

This thesis is done in weaving section of Bahir Dar textile Share Company. The

raw material come from spinning section in the form of cone which; is delivered

to preparation section of weaving for warping production. Then the warp beams

will be loaded to sizing machine to produce weavers‟ beam which will be loaded

on loom by knotting or gaiting if it is new article. Finally looms run to produce

fabric from the beam and cone used as weft which comes from spinning section.

18

3.2.1 Evaluation of yarn quality (using ATSM standards)

Yarn strength and elongation

Uster Tensorapid 4 is used for testing tenacity of the yarn. As the extension

continues, the tension in the sample reaches to its maximum value and it breaks

at weakest point. A care is taken during yarn withdrawal that yarn path should not

be obstructed. Testing speed used is 5000 mm per minute. Testing yarn length is

500 mm. Mean values and C.V.% of tensile strength and elongation are

calculated.

Figure3.1 uster tensorapid

Yarn evenness, imperfections, hairiness, and twist

Measurements of yarn unevenness and imperfections were determined using

evenness tester. The yarn irregularity in terms of U% and the imperfections in

19

terms of thick places, thin places, hairiness, twist, and neps per thousand meters

of yarn are evaluated. The sensitivity setting for the determination of

imperfections was - 50% for thin places, +50% for thick places and +280% for

neps.

Determine weft yarn properties before and after steaming

Determine warp yarn properties after sized

Figure3.2 Uster tester-5

20

3.2.2 Study of both warp and weft yarn breakage

Study yarn breakage rate on air jet looms

Study yarn breakage rate before and after steaming on air jet loom

These studies are carried out to determine the number of warp and weft breaks

which occurred when the loom run. The total number of picks inserted, number of

warp breaks, number of weft breaks and loom efficiency that occur will be

recorded and calculated yarn breakage determination was conducted, using air

jet looms at BDTSC. When weaving for a period of one hour at a loom speed of

600 revolutions per minute (600 rpm),using a reed width of 1.6 m, and producing

a plain fabric with 24 ends per centimeter (24 ends/cm) and 18 picks per

centimeter the acceptable number of warp and weft breaks for 100% cotton yarn.

Breakage study article specifications

Article: Bed sheet 160cm

Design: plain structure

Warp density = 24 ends /cm

Weft density = 18 picks/cm

Warp / weft = 20/20 Ne

Number of end = 4080

Reed width = 160cm

RPM = 600

21

Figure3.3 air jet weaving machine

3.2.3 Observations

Information and data related to general information about yarn breakage in

weaving and specific technical data which will be collected by; critical observation

to the shop floor work methods, systems and procedures, problems occurring

and their remedies, checking the status of loom and sizing, qualities running on

each loom and note down the particulars mentioned on the loom card, checking

the atmospheric conditions and the preparatory processes particularly in the

aspects of process parameters and quality.

3.2.4 Data analysis

Minitab 15 software was used for analyzing the experimental data. Analysis of

Variance (ANOVA) was used to detect the significant effects of these variables.

22

CHAPTER FOUR

RESULT AND DISCUSSION

4.1 Effect of yarn conditioning on breakage

Table 4.1 determination unconditioned of yarn tenacity and elongation

Table 4.1 shows the result of grey yarn test by which 10 cones samples are

taken from rotor at random and tested with 10 replicates. From this table the

M/c Time to break

(s)

B-force

(cN)

Elongation

(%)

Tenacity

cN/tex

O.E2 0.34 300.1 5.74 10.16

O.E5 0.35 287.5 5.75 9.74

O.E3 0.34 279.5 5.69 9.46

O.E6 0.31 275.1 5.16 9.32

O.E5 0.37 315.6 6.09 10.69

O.E2 0.29 198.4 4.88 7.72

O.E6 0.35 255 5.87 8.64

O.E3 0.32 221.7 5.35 7.51

O.E2 0.37 302 6.15 10.23

O.E3 0.34 264.3 5.64 8.95

Mean 0.31 269.92 5.632 9.24

Cv 9.9 15.5 9.8 15.5

Min 0.22 173.7 4 5.88

Max 0.37 361.9 7.07 12.26

Usp07 >95 72 >95

Number of tests 10 samples each 10 replicates

23

tenacity is 9.24 cn/tex and elongation 5.63%. The Uster statistics percentage of

tenacity is greater than 95 but; for elongation less than 95. Analyzing the data,

tenacity of single yarn strength is expected to be 13- 14 cn/tex and CV of tenacity

is less than 7% instead of 9.24 cn/tex and 15.5 respectively. Elongation at break

of single yarn is 5.63% which are accepted but the CV is 9.8% which is above

7%. The tenacity of unconditioned yarn is low as compare to btra standard.

Table 4.2 ANOVA analysis of yarn tenacity and elongation

Data Mean Variance N F P-value

B-force 269.92 1349.86178 10 509.996 0

Elongation 5.632 0.15906 10

Tenacity 9.242 1.10902 10

N: Total sample size

At the 0.05 level, the means are significantly different.

Figure4.1 determination of yarn tenacity and elongation

5.63

9.14 9.8

15.5

(%) cN/tex

Elongation Tenacity

Mean

Cv

24

Yarn strength, which is considered to be the most important property of spun

yarns, is largely influenced by the tenacity, length, length uniformity, short fiber

content and fineness (micronaire) of the constituent cotton fibers. If the

micronaire is coarse, the number of fibers in the yarn cross section will be less.

This always results in lower strength and lower elongation. Elongation and

tenacity plays a very critical role in reduction of yarn breakages. The elongation

depends upon the length of the fiber and also on twist per inch. So; from this can

conclude lower the yarn strength and elongation will lead to more yarn breakages

during weaving.

25

Table 4.3 determination of conditioned yarn tenacity and elongation

M/c Time to

break (s)

B-force

(cN)

Elongation

(%)

Tenacity

cN/tex

O.E2 0.38 380.3 6.33 12.88

O.E5 0.37 357.2 6.14 12.1

O.E3 0.38 374.6 6..36 12.7

O.E6 0.37 368.6 6.15 12.5

O.E5 0.38 389.7 6.36 13.2

O.E2 0.38 362.6 6.39 12.28

O.E6 0.33 347.5 5.57 11.76

O.E3 0.38 337.0 6.24 11.41

O.E2 0.39 385.8 6.50 13.06

O.E3 0.37 351.7 6.16 11.91

Mean 0.37 365.5 6.184 12.38

Cv 8.2 8.3 8.2 9.6

Min 0.21 201.3 4.12 6.82

Max 0.43 494.4 7.15 16.74

Usp07 79 67 89


Table 4.3 shows the result of conditioned yarn determine by which 10 cones

samples are taken from yarn steamer machine and tested with 10 replicates.

From this table the mean of conditioned yarn tenacity is 12.38cN/tex & elongation

is 6.184%. It is better as compare to btra standard. As yarn strength and

elongation increases less yarn breakages during weaving.

26

Table 4.4 ANOVA analysis of conditioned yarn


B-force 365.5 301.46444 10 4204.3084

0

Elongation 6.184 0.06803 10

Tenacity 12.38 0.34847 10


Table 4.5 comparison of conditioned and unconditioned yarn properties

Tenacity cN/tex Elongation (%)

Unconditioned 9.24 5.63

Conditioned 12.38 6.184

Figure4.2 conditioned and unconditioned yarn tenacity and elongation

Table4.3, 4.4 and figure4.2 shows the tenacity and elongation of conditioned

yarn greater than unconditioned one. Because of yarn conditioning improves

yarn qualities (like; tenacity and elongation). Analyzing the data, tenacity of

9.24

5.63

12.38

6.184

0

2

4

6

8

10

12

14

Tenacity cN/tex Elongation (%)

UnconditionedConditioned

27

conditioned yarn strength is greater than 4.14% to that of unconditioned yarn &

loss in elongation at break of single yarn is 0.55% to that of unconditioned yarn.

So; we can see from tables 4.1 and 4.3 using unconditioned yarn is affected the

yarn quality & using conditioned yarn will improve the quality & production.

Sufficient amount of conditioned yarn should be supplied to the loom shed to

reduce yarn breakage. So; can conclude the tenacity and elongation of

conditioned yarn is better as compare to unconditioned one based on btra

standard.

4.2 Effect of hairiness and imperfections on yarn breakage

Table 4.6 determination of yarn imperfection and hairiness

M/c U% CVm% Thin-

50%/km

Thick+50

%/km

Nep

+280/km

Hairiness

Index

SH

O.E2 10.72 13.58 0.0 34.0 46.0 5.51 1.51

O.E5 10.67 13.45 2.0 34.0 28.0 5.11 1.44

O.E3 10.74 13.57 4.0 34.0 34.0 5.15 1.47

O.E6 10.94 13.82 2.0 44.0 52.0 5.08 1.43

O.E5 12.61 16.08 26.0 238.0 120.0 5.38 1.57

O.E2 11.61 14.68 6.0 58.0 40.0 5.38 1.55

O.E6 10.38 13.09 0.0 18.0 22.0 5.11 1.42

O.E3 10.87 13.75 4.0 38.0 46.0 5.03 1.40

O.E2 10.92 13.82 6.0 16.0 28.0 4.99 1.40

O.E3 11.63 14.70 10.0 54.0 62.0 5.16 1.46

Mean 11.11 14.05 6.0 56.8 47.8 5.19 1.46

CV 5.9 6.2 127.7 114.5 58.9 3.3 4.1

Max 12.61 16.08 26.0 238.0 120.0 5.51 1.57

Min 10.38 13.09 0.0 16.0 22.0 4.99 1.40

Number

of tests

10 samples each 10 replicates

28

Table 4.6 shows the result of yarn test by which 10 cones samples are taken

from rotor at random and tested with 10 replicates. The results from the

instrument are; U%, CVm%, thick places, thin places, neps and hairiness. From

table 4.6 the means of U% is 11.109, CVm% is 14.05, thin places is 6.0, thick

places is 56.8, neps is 47.8 and hairiness is 5.19%. And also the coefficient of

variations of U% is 5.9, CVm% is 6.2, thin places is 127.7, thick places is 114.5,

neps is 58.9 and hairiness is 3.3%. The btra standard thin places -50%, thick

places 50%, and neps 280% are 15, 10, and 30 respectively.

Table 4.7 ANOVA analysis of yarn hairiness and imperfection

Data Mean variance N F P-value

U% 11.109 0.43428 10

6.09668

0.0

CVm% 14.054 0.7632 10

Thin-50%/km 6 58.66667 10

Thick+50%/km 56.8 4232.17778 10

Nep

+280/km

47.8 793.28889 10

Hairiness

Index

5.19 0.02973 10


29

Figure4.3 yarn imperfection and hairiness

Yarns with poor evenness will have more thick and thin places along yarn length.

The yarn imperfection includes thin places, thick places and neps which have

great influence on the yarn breakage and quality of the fabric. It is generally

observed that all thick and thin places in the yarns are weak places, because at

think place there is no twist per meter and at thin place more twist per meter than

normal while neps in the yarn are either due to presence of immature fibers or

due to poor carding operation.

0

20

40

60

80

100

120

140

Mean

CV

30

4.3 Effect of twist on yarn breakage

Table 4.8 determination of yarn twist

M/c TPM Extension (%) TF

O.E2 920.8 4.6 158.1

O.E5 877.9 3.7 150.7

O.E3 925.9 4.9 159

O.E6 914.5 4.7 157

O.E5 925.5 4.5 158.9

O.E2 919.1 4.00 157.8

O.E6 938.1 5.4 161.1

O.E3 868.8 4.5 149.2

O.E2 888.8 4.7 152.6

O.E3 914.7 5.3 157.1

Mean 909.4 4.63 156.15

CV 522.0298 0.269 15.4383

Max 938.1 5.4 161.1

Min 868.8 3.7 149.2


Table 4.8 shows the result of yarn test by which 10 cones samples are taken

from rotor at random and tested with 10 replicates. From table 4.8 the mean of

TPM is 909.4, extension is 4.63% and TF is 156.15. From this table can analyze

as twist per meter increase both extension and twist factor increase. So; can

conclude as the yarn twist increase; the strength of yarn also increases.

31

Table4.9 ANOVA analysis of yarn twist


TPM 909.41 522.02989 10 13101.06245

0

Extension 4.63 0.269 10

TF 156.15 15.43833 10


Figure 4.4 yarn twist factor and twist per meter

Strength of the yarn increases with the increase in twist factor. At low twist factor

yarn breaks mainly as result of fiber slippages. So in order to reduce the yarn

breakage there should be appropriate twist in the yarn as compere to btra

standard.

909.4

156.15

522.0298

15.4383 0

200

400

600

800

1000

TPM TF

Mean

CV

32

4.4 Effect of sized yarn tenacity and elongation on yarn breakage

Yarn property is checked at different stages of manufacturing in gray and after

sizing.

Table 4.10 determination of sized yarn tenacity and elongation

M/c Time to

break (s)

B-force

(cN)

Elongation

(%)

Tenacity

cN/tex

O.E2 0.22 420.0 3.74 14.22

O.E5 0.20 398.4 3.37 13.49

O.E3 0.22 378.6 3.64 12.82

O.E6 0.23 416.9 3.76 14.12

O.E5 0.19 351.5 3.16 12.00

O.E2 0.22 377.9 3.65 12.8

O.E6 0.19 394.6 3.12 13.36

O.E3 0.27 450.2 4.42 15.25

O.E2 0.23 400.7 3.78 13.57

O.E3 0.22 427.3 3.67 14.47

Mean 0.22 401.6 3.63 13.61

Cv 12.8 10.3 12.8 10.3

Min 0.15 320.4 2.58 10.85

Max 0.3 506.4 4.95 17.15

Usp07 35 >95 28


Table 4.10 shows the result of sized yarn test by which 10 samples are taken from

sizing machine and tested with 10 replicates. The results from the instrument are

breaking force, elongation percentage, and tenacity. For the sized yarn, 20 Ne the

33

tenacity is 13.61 cN/tex and elongation 3.63%. The uster statistics percentage is

greater than 95% for elongation and less than 95% for tenacity. Analyzing the

above data, tenacity of sized yarn strength is expected to be greater than 4.37%

to that of the unsized yarn and CV% of tenacity is less than 7% for sized open end

yarn. Loss in elongation at break of sized yarn is expected to be less than 2% to

that of the unsized yarn.

Table4.11 ANOVA analysis of sized yarn tenacity and elongation


B-force 401.61 806.20544 10 1914.139

0

Elongation 3.631 0.13625 10

Tenacity 13.61 0.89024 10


Table 4.12 comparison of unsized and sized yarn elongation and tenacity

Elongation (%) Tenacity cN/tex

Sized 3.63 13.61

Unsized 5.63 9.24

34

Figure4.5 comparison of sized and unsized yarn elongation and tenacity

Table 4.12 and figure 4.5 shows tenacity of sized yarn greater than unsized yarn

but the elongation is lower than unsized yarn. Since sizing increases yarn

strength. The elongation of sized is 3.63% which is below btra standard. So; the

sized warp sheet of cotton yarn always should have 4-5% elongation to reduce

breakages on loom.

3.63

5.63

13.61

9.24

0

2

4

6

8

10

12

14

16

sized Unsized

Elongation (%)

Tenacity cN/tex

35

4.5 Determination of yarn breakages

Table 4.13 determination of unconditioned yarn breakages

m/c

No

RP

M

Ti

me(

hr)

Warp

Stop

Warp

CMP

X

Weft

Stop

Weft

CMP

X

Other(e

lect/mec

ha)

Oth

erCM

PX

No. of

picks

Met

er

Loo

m

effi.

(%)

1903 600 1 2 8.5 14 59.4 1 4.2 23580 13.1 65.5

1904 600 1 3 13.1 13 56.8 1 4.3 22860 12.7 63.5

16a01 600 1 2 8.1 11 44.3 0 0 24840 13.8 69

1602 600 1 2 8.8 12 52.9 0 0 22680 12.6 63.5

1801 600 1 1 4.8 15 72.5 1 4.8 20700 11.5 57.5

1802 600 1 2 9.9 16 79.4 1 4.9 20160 11.2 56

Mean 600 1 2 8.87 13.5 60.9 0.667 3.03 22470 12.5 62.5

Table 4.13 shows the result of unconditioned weft yarn breakages determine by

using 20 cones yarns are taken from the rotor open end machine after tested the

parameter & tested with 6 machines in loom shed within two weeks. The results

from loom shed are weft stoppage, warp stoppage, other stoppages & efficiency.

The total yarn break rates are;

= (warp+ weft+ other) break rates

= 8.87+60.9+3.03

= 72.80 breaks

Analyzing the data breakage of unconditioned yarn in air jet loom is expected to

be 6.6breakages/hr instead 72.8breaks/hr. That is higher than the btra standard.

36

Table4.14 ANOVA analysis of unconditioned yarn breaks


Warp breaks 8.86667 7.25067 6 974.49767 0

Weft breaks 60.88333 167.08567 6


Table 4.15 determination of conditioned yarn breakages

m/c

No

RP

M

Time

(hr)

Warp

Stop

Warp

CMP

X

Weft

Stop

Weft

CMP

X

Other(el

ect/mech

a)

Oth

erCM

PX

No. of

picks

Meter Loom

effi.

(%)

1903 600 1 2 6.1 8 24.3 0 0 32940 18.3 91.5

1904 600 1 1 3.2 10 31.9 1 3.2 31320 17.4 87

1601 600 1 2 6.8 11 37.7 1 3.4 29160 16.7 81

1602 600 1 1 3.3 9 29.4 2 6.5 30600 17 85

1801 600 1 3 10.4 10 34.7 1 3.4 28800 16 80

1802 600 1 2 6.6 11 36.1 0 0 30420 16.9 84.5

Mean 600 1 1.8 6.1 9.83 32.3 0.83 2.75 30540 17.0 84.83

Table 4.15 shows the result of conditioned weft yarn breakage determine by

20 cones yarns are taken from the steamer machine & tested with 6 machines in

loom shed within two weeks. The results from loom shed are weft stoppage,

warp stoppage, & efficiency record.

From this table the weft breakage of conditioned yarn is far from the norms but it

is preferable than unconditioned weft yarn. The btra standards of warp and weft

yarn breakages are 2.6 and 3.2 breakages per hour respectively. The breakage

rate of weft yarn is high as compare to warp breakage rate.

37

Table4.16 ANOVA analysis of conditioned yarn breaks


Warp breaks 6.06667 7.09467 6 128.01283

0

Weft breaks 32.35 24.383 6


Table 4.17 comparison of unconditioned and conditioned yarn breakages

Weft breaks/hr Warp breaks/hr

Unconditioned 60.9 8.87

Conditioned 32.35 6.1

Figure 4.6 Comparison of unconditioned and conditioned yarn breaks

Table 4.17 and figure 4.6 show the breakage rate of unconditioned yarn is

greater than conditioned yarn. Because of yarn steaming improves yarn quality.

So; in order to minimize yarn breakage in weaving yarn steaming is necessary.

60.9

8.87

32.35

6.1

0

10

20

30

40

50

60

70

Weft breaks/hr Warp breaks/hr

unconditioned

Conditioned

38

Therefore yarn steamer machine should be used in order to improve the yarn

quality unless a serious shortage of conditioned cone occurs in the loom shed.

Loom yarn breakages analysis

Total picks = Fabric width X total meter x100 = 1.6 x 18.3 x100 = 3 2940picks

Warp Break = warp breaks x 100, 000 picks

No. of picks

= 2 x 100,000 picks

32940 picks

= 6.1 breaks

Weft Breaks = 8 weft breaks x 100,000 picks

32940picks

=24.3 breaks

loom efficiency = Fabric width x 32940picks x100

Fabric width x rpm x time

= 1.6 x 32940pics x100

1.6 x 600 x 1hr x 60min

= 91.5%

39

4.6 Causes of yarn breakages and solutions

The yarns obtained from the spinning process has to undergo various processes

such as winding, warping, sizing and weaving before it is converted into fabric.

During its journey from winding to weaving, the yarn has to withstand various

kinds of stress offered by different mechanisms. Yarn breakages on air jet

weaving machine can be classified in to two categories. These are weft

breakages and warp breakages.

Causes of weft breakages

Weft breakages are measured at loom cycle degree of 360. During determination

of yarn breaks on air jet loom I observed that causes of weft yarn breaks on air

jet loom are poor yarn quality (more imperfection, low strength, high and low

twist, high hairiness etc.), snarls after weft pre feeder, snarls on cone, improper

cone forming, slough off at cone, wrong drawing-in and early cutter timing of weft

cutter.

Causes of warp breakages

Warp breakages are mainly divided into four zones. These are right hand side

warp breaks, left hand side warp breaks, right hand side leno breaks and left

hand side leno breaks. And also warp yarn breakages occurs at middle, back

side and healed frame.

40

A. Causes of r.h and l.h side leno breakage

During determination of yarn breaks on the loom, I observed that left and right

hand side leno yarn breaks due to damaged reed, improper leno bobbin thread

tension and alignment of leno device and leno bobbin stand is not proper.

B. Causes of warp breakages at r.h and l.h side, middle, back side and

healed frame

Generally, during determination of yarn breaks on the loom, I observed that warp

yarn breaks mainly due to miss ends, wrong drawing-in, floating ends, crossed

ends, poor yarn quality (more yarn thin places, thick places, neps, etc.), loose

knots, more tension on warp sheet, damaged back rest roller, healed frames,

drop wires, worn out back rest bearings, improper healed frame height, improper

warp and sizing beam forming and atmospheric conditions.

As I observed during yarn breakage determination majority of breakage are

mainly confined to the shedding zone (i.e., from fell to lease rods or drop wires).

If proper care and maintenance of machine is done the number of breakages can

be reduced for giving better productivity and good quality fabric. Use yarn

steaming machine and correct temperature and RH % according to the standard.

In weaving the optimum temperature and relative humidity are 20℃ - 31℃ and 6o

% – 75% respectively.

Since high moisture increases yarn strength, elasticity and smoothness while;

less moisture reduces strength, elasticity and smoothness. Process appropriate

41

raw materials in spinning in order to produce quality yarn since; both tensile

strength and elasticity depend on fiber and spinning characteristics. Prepare the

report of yarn breakages in each preparatory process and loom to give feedback;

so the feedback may provide to the beck process for instance to spinning

section. Study and prepare report of loom stoppages on the different loom having

same qualities. Study the yarn breakage due to poor yarn quality, different

mechanical, electronic, and electrical parts of the loom and rectify them.

42

CHAPTER FIVE

CONCLUSION AND RECOMMENDATION

5.1 Conclusion

In weaving industry one of the most frequent facing problems is breakages of

both warp and weft yarns which not only reduce the production rate and also

deteriorate the quality of the produced fabric. Loom stoppages during the

weaving process usually occurs due to warp breaks, weft breaks, mechanical

breakdown, electrical faults, beam gaiting, shortage of spare parts, power

interruption, beam changing, cleaning, oiling and lubricating. Among these warp

and weft breaks occur more frequently than the rest due to poor yarn quality

(high yarn imperfection, low and high twist, low yarn strength, high yarn

hairiness, etc.), uncontrolled room temperature and relative humidity, excessive

loom speed, and uncontrolled warp tension. Other causes can be due to bad

knots on warp yarn, poor size pick-up, loose ends, improper cone forming,

slough off at cone, snarls after weft pre feeder, snarls on cone, damaged back

rest roller, healed frames, drop wires and improper warp beam forming. Majority

of yarn breaks are mainly occurred in the shedding zone (from back rest to fell).

In order to reduce yarn breakage, increase productivity of both machines and

labor also the quality of the produced fabric it is essential to select the

appropriate yarn and steaming it to improve yarn quality. So; to reduce yarn

breakages during weaving, the yarn which comes from spinning should meet the

43

btra standards of yarn properties (strength, yarn hairiness, yarn imperfections

(thin, thick places and neps)), twist per inch, and yarn elongation). In the study I

conclude that breakage rate of conditioned yarn is lesser than unconditioned

yarn. The breakage rate of both warp and weft unconditioned yarn is 8.87 and

60.9 breaks per hour respectively and the breakage rate of both warp and weft

conditioned yarn is 6.1 and 32.35 breaks per hour respectively. The btra

standard warp and weft yarn breakages are 2.6 and 3.2 breakages per hour

respectively. From this the breakage rate of conditioned yarn is better as

compare to btra standard. Since yarn steaming improves yarn quality

(elongation, tenacity etc.). And also yarn should be steamed before it coming to

weaving room to minimize yarn breaks on loom during weaving.

5.2 Recommendation

The yarn received from spinning does not meet the latest standard yarn properties.

So; an improvement has to be made in spinning section to reach the grey yarn

strength to 13 to 14cN/tex and elongation 5.5% to 7% (process quality raw

materials by controlling all process quality parameters properly) and other yarn

parameters as indicated in the norm table (see appendices 2).

During mixing the following parameters should be done properly

Proper selection of raw material (high staple length, fineness, strength,

elongation, maturity, etc.).

Verifying the lot numbers and bale numbers before taking the mixing

44

Clearly defining/understanding the quantity of materials to be taken from each

mixing component

Taking materials from each bale uniformly while making a stack mixing

yarn should be conditioned before coming to weaving preparatory and

looming by using yarn steaming machine

The elongation of sized warp sheet of cotton yarn always should be 4-5% to

minimize warp breakages on loom.

The machines automation system, moisture control, automatic speed adjustment

control systems are not properly working. So, intervention is required in these

machines to get good quality yarn resulting enhancement of yarn breakage

reduction and productivity in weaving.

45

4. REFERENCE

1. Ahung Kyaw, (2004), Soe ET. al., Text. Res. J. 74 (9)

2. Altas, S., and Hüseyin Kadoğlu, H. (2012). Comparison of Conventional Ring,

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Journal of Engineered Fibers and Fabrics, Volume 7

3. Azzam, H.A. and Mohamed, S.T. (2005). Adapting and Tuning Quality

Management in Spinning Industry, AUTEX Research Journal, Vol. 5, No (4)

4. B. C. Goswami, R. Anandjiwala and D. M. Hall , Marcel Dekker (2004), Textile

Sizing

5. Bahir Dar Textile Share Company(2016) weaving section annual report

6. Barella, A., (2003) "Textiles" Journal of Textile Institute, Volume 21

7. Basal, G. & Oxenham, W. (2006), Comparison of properties and structures of

compact and conventional spun yarns. Textile Research Journal, 76.

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49

5. APPENDICES

Appendices 1

Uster statistics rating of quality levels of warp yarns

Quality parameters

Air jet Air jet Projectile Projectile

Projectile

Rapier

Rapier

Count 50s 60s 50s 60s 80s 40s 60s

Tensile

strength

Betwee

n 25-

50%

75% 50% Between

75-95%

Betwee

n 75-

95%

Betwee

n 5-

25%

Betwee

n 75-

95%

CV of Tensile

strength (%) 5%

Betwee

n 75-

95%

Between

25-50% 75%

Betwee

n 75-

95%

Betwee

n 25-

50%

Betwee

n 25-

50%

Breaking

elongation (%)

Betwee

n 25-

50%

95% 75% 75% 95% 75% 95%

Hairiness index 50% 50% Between

5-25% 75% 75%

Betwee

n 5-

25%

25%

Normal

imperfections

Normal

imperfec

tions

Normal

imperfec

tions

Normal

imperfect

ions

Normal

imperfecti

ons

Normal

imperfe

ctions

Normal

imperfe

ctions

Normal

imperfe

ctions

Thin places\km

(-50%)

Betwee

n 5-25%

Betwee

n 5-25% 5%

Between

25-50%

Betwee

n 5-25% 5% 50%

Thick

places\km

(+50%)

Betwee

n 5-25%

Betwee

n 5-25%

Between

5-25%

Between

5-25% 25% 5% 50%

Neps\km(+200) Betwee

n 5-25%

Betwee

n 5-25%

Between

5-25%

Between

5-25%

Betwee

n 25-

50%

Betwee

n 25-

50%

Betwee

n 5-

25%

Total

imperfections

Betwee

n 5-25%

Betwee

n 5-25%

Between

5-25%

Between

5-25%

25% 25% 25%

50

Appendices 2

20Ne 100% cotton Yarn quality requirement for weaving (btra standard)

SI.No. Yarn Parameters Values

1 Yarn count 20Ne (OE)

2 Actual count 20

3 Count CV% <2.0%

4 Twist per meter <890

5 Yarn hairiness having length

more than 3mm

3 per meter

6 Evenness CV% <13.0

7 Imperfections

Thin - 50%

Thick+50%

Nep+280%

15

10

30

8 Yarn strength cN/tex

B-Force cN

13-14

380 – 415

9 Yarn elongation % 5.5 - 6.0

51

Appendices 3

BDTSC Weaving machines specifications

Make &

Model

Width

of

Looms

(cm

No. of

Looms

Average

Speed

(rpm)

Type of

Weft

Insertion

No. of weft

Accumulators

Type of

Shedding

Smote

Sm 93

160-

240

112 260-320 Rapier 2 Cam

Picanol

Omniplus

800

160-220 66 500-700 Air jet 2 Cam

study the causes of yarn breakage and possible

Documents