Investigation Periodic Faults in Yarn

i

INVESTIGATIVE STUDY OF PERIODIC YARN FAULTS AND

ITS REMOVAL BY USING GEARING ANALYSIS

A Thesis Submitted To

Bahauddin Zakariya University College of

Textile Engineering, Multan

By

MUHAMMAD RIZWAN 11-TE-13

MUHAMMAD MUNAWAR 11-TE-29

MUHAMMAD ASAD 11-TE-30

YASIR AKHTAR 11-TE-40

BAHAUDDIN ZAKARIYA UNIVERSITY COLLEGE OF TEXTILE

ENGINEERING, MULTAN

December, 2015

ii

CANDIDAT’s DECLARATION

We certify that the thesis entitled” Investigative Study Of Periodic Yarn Faults And Its

Removal By Gearing Analysis” submitted for the degree of B.sc Textile Engineering is

the result of our own research, except where otherwise acknowledged, and that this thesis in

whole or in part has now been submitted for an award, including a higher degree, to any

other university or institution.

Muhammad Rizwan

Signed: ---------------------- Date: 14/12/2015

Muhammad Munawar

Signed: ---------------------- Date:14/12/2015

Muhammad Asad

Signed: ---------------------- Date:14/12/2015

Yasir Akhtar

Signed: ---------------------- Date:14/12/2015

iii

CERTIFICAT

It is to certify that this thesis entitled “Investigative Study of Periodic Yarn Faults

and Its Removal by Using Gearing Analysis” has been accepted as a partial

fulfillment of the requirement for the degree of B.sc Textile Engineering in

Bahauddin Zakariya University College of Textile Engineering Multan.

Associate Supervisor: -------------------- Principle Supervisor: ---------------------

Project Coordinator: --------------------- External Examiner: ----------------------

Vice Principal: ------------------------

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DEDICATION

To our beloved parents and respected teachers

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ACKNOWLEGEMENT

First of all we want to thank AL-MIGHTY ALLAH who made us able to do this.

We are thankful to our parents who like to see us successful in all fields of life and

pray for us to have a happy and long live.

We would like to express my special thanks of gratitude to my teacher Mr.

Muhammad Furqan Khurshid as well as our vise principal Mr. Tahir Bappi and Mr.

Ahsanullah (General Manager of Unit No.4, Fazal Cloth Mills, Fazal Nagar Jhang

Road, Muzaffargarh) who gave us the golden opportunity to do this wonderful

project on the topic ,“Investigative Study Of Periodic Yarn Faults And Its Removal

By Using Uster Quantum” which also helped using doing a lot of Research and we

came to know about so many new things. We are really thankful to them.

We want to thank administration and staff of Unit No.4, Fazal Cloth Mills, Fazal

Nagar Jhang Road, Muzaffargarh who were very kind and supportive to us.

Especially to Mr. Ahsanullah(General Manager of Unit No.4, Fazal Cloth Mills,

Fazal Nagar Jhang Road, Muzaffargarh) who helped us throughout the project and

gave free hand to perform our experiment.

We are thank full to our beloved senior Laal Khan, great teacher and again project

supervisor Mr. Furqan Khurshid, the guidance of whom has been always source of

light in darkness and he was always available to us. In difficult process of compiling

and writing of our project we are very thankful to him who told us the right way of

doing this.

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ABSTRACT

It has been widely reported that periodic faults in cotton yarn are one of the main

reasons of yarn rejection from weaving mill. This thesis has been undertaken to

study periodic faults produced in cotton ring spinning mill, its rectification and

prevention from occurring. The purpose of periodic yarn fault detection system was

to identify defective part in the machine. This system is suitable for identifying the

source of periodic fault on the machine. It was developed because spectral analysis

of machines with complex driving systems requires time and work-consuming

calculations, which make it considerably more difficult to quickly find the cause of

the detected periodicity in the stream of fibers.

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TABLE OF CONTENTS

CHAPTER # 1 INTRODUCTION ........................................................................ 1

1.1 Yarn ............................................................................................................... 1

1.2 Types of Yarn ................................................................................................. 1

1.2.1 Filament Yarn .......................................................................................... 1

1.2.2 Staple or Spun Yarn ................................................................................. 1

1.3 Manufacturing Process of Staple or Spun Yarn ............................................... 2

1.4 Brief Introduction of Departments .................................................................. 3

1.4.1 Blow Room Process ................................................................................. 3 1.4.2 Carding Process ....................................................................................... 3

1.4.3 Combing process ...................................................................................... 4

1.4.4 Drawing frame Process ............................................................................ 4

1.4.5 Roving frame ........................................................................................... 5

1.4.6 Ring Spinning Process ............................................................................. 5

1.4.7 Cone Winding Process: ............................................................................ 7

1.5 Yarn Faults ..................................................................................................... 8

1.6 Yarn Faults Classification ............................................................................... 8 1.6.1 Classimat Faults ....................................................................................... 9

1.6.2 Deviation in Yarn Quality Faults .............................................................. 9

1.6.3 Periodic Yarn Faults ............................................................................... 16

CHAPTER #2 Materials and Method ................................................................. 26

2.1 Material ........................................................................................................ 26

2.2 Method ......................................................................................................... 28

2.2.1 Identify the periodic fault length by mass spectrogram ........................... 28

2.2.2 Analysis the Gearing System .................................................................. 29

2.2.3 Identify Origination Point of Yarn Fault ................................................. 30 2.2.4 Rectification of Yarn Faults ................................................................... 30

CHAPTER #3 RESULTS AND DISCUSSION .................................................. 31

3.1 Investigation and rustication of periodic faults at breaker .............................. 31


3.1.2 Analysis the gearing system ................................................................... 32

3.1.3 Identify Origination Point of Yarn Fault ................................................. 33

3.1.4 Rectification of Yarn Faults ................................................................... 34

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3.2 Investigation and rustication of periodic faults at Finisher ............................. 35



3.2.3 Identify origination point of yarn fault .................................................... 37

3.3 Investigation and rustication of periodic faults at Simplex ............................ 39 3.3.1 Identify the periodic fault length by mass spectrogram ........................... 39


3.3.3 Identify origination point of yarn fault .................................................... 42

3.3.4 Rectification of Yarn Faults ................................................................... 42

3.4 Investigation and rustication of periodic faults at Ring .................................. 43



3.4.3 Identify Origination Point of Yarn Fault ................................................. 45 3.4.4 Rectification of Yarn Faults ................................................................... 46

Conclusions .......................................................................................................... 47

References ............................................................................................................ 47

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LIST OF FIGURES

FIGURE 1.1: FLOW CHART OF SPUN YARN MANUFACTURING PROCESS ...................... 2 FIGURE 1.2: CLASSIFICATION OF YARN ..................................................................... 8 FIGURE 1.3: CLASSIFICATION MATRIX IN CLASSIMAT ................................................ 9 FIGURE 1.4: EFFECT OF COUNT VARIATION ON THE FABRIC SURFACE ..................... 10 FIGURE 1.5: HAIRINESS ON THE SURFACE OF YARN ................................................ 14 FIGURE 1.6: DIFFERENCE IN PERIODICITY ................................................................ 17 FIGURE 1.7: MOIRÉ EFFECT..................................................................................... 18 FIGURE 1.8: AMPLITUDE OF PERIODIC FAULT .......................................................... 19 FIGURE 1.9: NORMAL MASS SPECTROGRAM ............................................................ 20 FIGURE 1.10: EXAMPLE OF SPECTROGRAM OF CHIMNEY FAULT .............................. 22 FIGURE 1.11: EFFECT OF CHIMNEY FAULT ON YARN .............................................. 22 FIGURE 1.12: EXAMPLE OF SPECTROGRAM OF HILL TYPE PERIODIC FAULT ............. 23 FIGURE 1.13: SPECTROGRAM AND YARN BOARD IMAGE OF A BAD OE YARN. ......... 25 FIGURE 2.1: SEQUENCE OF MACHINES FOR YARN PREPARATION ............................. 27 FIGURE 2.2: SPECTROGRAM REPRESENTING PERIODIC FAULT .................................. 28

FIGURE 2.3: DRAFTING ELEMENTS OF A RING SPINNING MACHINE WITH GEARING DRIVE ............................................................................................................. 29

FIGURE 3.1: GEARING DIAGRAM OF DRAWING BREAKER ........................................ 32 FIGURE 3.2: GEARING DIAGRAM OF DRAWING FINISHER ......................................... 36 FIGURE 3.3: GEARING DIAGRAM OF SIMPLEX FL-100 .............................................. 40 FIGURE 3.4: GEARING DIAGRAM OF RING FRAME RX-240 ....................................... 44

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LIST OF TABLES

TABLE 2.1: THE PROPERTIES OF COTTON ............................................................... 26 TABLE 2.2: PARAMETERS USED IN THE EXPERIMENTS ............................................. 27 TABLE 3.1: PERIODIC FAULT LENGTHS OF DIFFERENT PARTS OF BREAKER .............. 33 TABLE 3.2: PERIODIC FAULT LENGTHS OF DIFFERENT PARTS OF FINISHER ............... 37 TABLE 3.3: PERIODIC FAULT LENGTHS OF DIFFERENT PARTS OF SIMPLEX FL-100 .... 41 TABLE 3.4: PERIODIC FAULT LENGTHS OF DIFFERENT PARTS OF RING FRAME RX-240

....................................................................................................................... 45

1

Chapter: Introduction -------------------------------------------------------------------------------------------------------------------------

1.1 Yarn A yarn is defined as a product of substantial length and relatively small cross section

consisting of fiber and/or filament with or without twist.[1]

OR

A Yarn is long length continuous strand of twisted fibers of natural or synthetic

material, such as cotton, wool or nylon, used in weaving or knitting. [2]

The characteristics of spun yarn depend, in part, on the amount of twist given to the

fibers during spinning. A fairly high degree of twist produces strong yarn; a low

twist produces softer, more lustrous yarn; and a very tight twist produces crepe yarn.

Yarns are also classified by their number of parts. A single yarn is made from a

group of filament or staple fibers twisted together. Ply yarns are made by twisting

two or more single yarns. Cord yarns are made by twisting together two or more ply

yarns.

1.2 Types of Yarn There are two classifications of yarns that will be produced by spinning which are

Filament and Staple yarns.[3]

1.2.1 Filament Yarn

These yarns are made from long, and continuous strands of fiber. Most of them from

synthetic and only silk represents for natural fibers in filament.

1.2.2 Staple or Spun Yarn

Staple or spun yarns in other hand are made from short length of fibers. It can be

found from natural fibers or can be produced using synthetic as staple filament

yarns. As it is short length, staple fibers need to be held together with others in order

to get the long and continuous yarns.

2

1.3 Manufacturing Process of Staple or Spun Yarn Staple yarn manufacturing is a sequence of processes that convert raw cotton fibres

into yarn suitable for use in various end-products. A number of processes are

required to obtain the clean, strong, uniform yarns required in modern textile

markets. Beginning with a dense package of tangled fibres (cotton bale) containing

varying amounts of non-lint materials and unusable fibre (foreign matter, plant trash,

motes and so on), continuous operations of opening, blending, mixing, cleaning,

carding, drawing, roving and spinning are performed to transform the cotton fibres

into yarn.[3]

Figure 1.1: Flow Chart of Spun Yarn Manufacturing Process

3

1.4 Brief Introduction of Departments

1.4.1 Blow Room Process

Blow room is the initial stage in spinning process. The name blow room is given

because of the “air flow” And all process is done in blow room because of air flow.

Blow room is consisting of different machines to carry out the objectives of blow

room. In blow room the tuft size of cotton becomes smaller and smaller due to that

cleaning also done. Mixing of cotton is done separately as well as in blow room.

Compressed layer of bale is also open in blow room with the help of machine. Other

contamination in the cotton such as leaf, stone, iron particles, jute, poly

propylene, colored fibers, feather and other foreign material also remove from

cotton by opening and beating. Then open material feed to the next carding process

uniformly.[4]

1.4.2 Carding Process

Carding process is very important role in spinning mill. It helps us both way to open

the tuft into a single fiber and to remove the impurities and naps. Textile experts are

convinced for the accuracy of following statement.

“The card is the heart of spinning mill” and “well carded is well spun” (Vijykumar,

2007) [5]

Card feeding is done by two ways. One is manually and other is through chute feed

system. In manual case the lap which is produced in blow room and it is feed to the

card. In chute feed the material is feed through air flow system to card

machine. It is important to say that lower the feed variation better is the carding

quality. Lower the feed variation then draft variation will also be less. Then yarn

quality will be consistent. If the card is having auto leveler then nominal draft

should be selected properly. In some circumstances card also act as a cleaner

and remove a certain amount of short fiber. Approximately 90% cleaning

efficiency is achieved with the help of carding machine.[6]

4

1.4.3 Combing process

For getting high quality of yarn, one extra process is introduced which is called

combing process.

Combing is an operation in which dirt and short fibers are removed from sliver lap

by following ways. In a specially designed jaws, a narrow lap of fiber is

firmly gripped across its width. Closely spaced needles are passed through the fiber

projecting from jaws. Short fiber which we remove is called comber noil. The

comber noil can be recycled in the production of carded yarn. Yarn which is

get from comber sliver is called comber yarn. Carded sliver are combine into

comber lap in a single continuous process stage. Flat sheet of fiber which is get from

comber lap is fed into the comber in an intermediate.

There are different ways by which value of combing is used in the manufacturing of

cotton. By spinning point of view combing process makes more uniformity in the

yarn. Strength of yarn is also high because in combing process short fiber are

removed and only fiber having good strength remains. So it play very

important role for increasing the yarn strength. Because of straightened

condition of fibers combing makes possible spinning smoother and more

lustrous yarn. In combing process length of fiber are strong so it need less

twist produced then carded yarn. [7]

1.4.4 Drawing frame Process

Draw frame is simple and cheap machine. In spinning regarding to quality point of

view it play very important role .If its setting is not done properly then it affects yarn

strength and elongation. For improving quality draw frame is final process in the

spinning mill. It effects on quality especially on evenness of sliver. In the spinning

process there are chances of elimination of errors in draw frame machine. Draw

frame play very important role for the quality of yarn. Without it participation

quality can never be improved.[8]Drafting arrangement is the heart of the draw

frame. Drafting arrangement should be simple, stable design, should have

ability to produce high quality product. It should have high fiber control.

5

Auto leveler is also used to adjust and to improve the linear density of the

sliver. Without auto leveler it is very difficult to improve the quality of the draw

frame sliver.

1.4.5 Roving frame

It is an intermediate process in which fibers are converted into low twist lea called

roving. The sliver which is taken from draw frame is thicker so it is not suitable for

manufacturing of yarn. [7]

Its purpose is to prepare input package for next process. This package is to

prepare on a small compact package called bobbins. Roving machine is

complicated, liable to fault, causes defect adds to the production costs and

deliver the product. In this winding operation that makes us roving frame complex.

There are two main basic reasons for using roving frame. The roving sliver is thick

and untwisted. Because of it hairiness and fly is created. So draft is needed to

reduce the linear density of sliver. The ring drafting arrangement is not capable that

it may process the roving sliver to make the yarn.

Draw frame can represent the worst conceivable mode of transport and

presentation of feed material to the ring spinning frame.

1.4.6 Ring Spinning Process

Ring Spinning machine is used in textile industry to twist the staple fibers into a

yarn and wind on a bobbin for the winding section for more precise the yarn

to minimize the defects of end yarn. Ring machine is very important due to yarn

quality. Ring Spinning is the most costly step to convert fibers into yarn and

approximately 85% yarn produced in ring spinning frame all over the world. It is

made to draft the roving into a desired count and impart the desired twist to produce

the strength in the yarn. If twist is increased, yarn strength is also increased at

optimum limit.[2]

The input of ring frame is roving which comes from roving section this is final stage

where yarn is make. Here in this section need more drafting to reduce the liner

density of roving and more twist to make a yarn. The output of ring frame is yarn

which is wound on a ring bobbin which is used for next winding process.

6

1.4.6.1 Function of Ring Process

There is a different function of Ring Spinning process in which roving is

converted into yarn through passing different zone like drafting, twisting and

winding zone. There are three important zone of Ring processes below here. [9]

Drafting Zone

Twisting Zone

Winding Zone

1.4.6.1.1 Drafting Zone

Drafting is the first zone of ring process and is very important part of machine and

mostly effects on the evenness and strength of yarn. In quality point of view, there

are many points which are related to the quality of drafting system.

Type of the draft

Selection of drafting parts like apron, rubber cots and spacer.

Range of draft

Draft designing and setting

Service and maintenance

Type of perforated drum

1.4.6.1.2 Twisting Zone

It is the second zone and is also very important part of Ring machine in which

the strands of fiber are converted into a yarn by the twist inserted. The strength of

yarn is depend upon the amount of twist which are given in twisting zone and it is

most important than other zone due to required strength of yarn. There are some

very important points related to quality point of view in twisting zone are;

Material and type of traveler

Wear resistance

Lubrication of fiber

Smooth running

Spindle and Traveler Speed

7

1.4.6.1.3 Winding Zone

This is the last section of ring machine in which yarn is wound on the plastic bobbin

by the up and down movement of ring rail which is linked to a small motor. It is also

very important because the setting of ring rail makes coils of yarn on bobbin in such

a way that the Z-twist is not open during winding process. Some points are very

important during winding process. That’s are;

Ring rail speed setting

Bobbin material

No. of coils per inch

1.4.6.2 Ring Spinning Effects on Quality

Ring spinning is the first stage of post spinning in which yarn produced from

the roving installed on the hanger on the ring machine. Ring process is the heart of

textile plant and there is lot of factors effect on the yarn quality. Speed of machine

makes a major role on the yarn quality, as the speed increase of ring

machine, the imperfection (Neps 200%, Thick +50, Thin -50) of yarn increase.

Hairiness is also affected in ring production process and mainly produced by

the movement of burnt traveler and high speed of machine.CV of count is also very

important and ring spinning process is the last stage of process where we can reduce

the CV of yarn count. Imperfection of yarn count in quality point of view is so

important that every customer required this quality standard, that imperfection

should be minimum as possible. [9]

1.4.7 Cone Winding Process:

It is the last section of yarn manufacturing process where auto cone machines are

installed and take an input material from ring spinning section as a yarn bobbin and

give a yarn on paper cone after passing detecting instrument as an output. In

winding section, there are lot of heads in auto cone machines use to wound the yarn

from ring bobbin yarn to paper cone yarn. Now days, there are some companies to

manufacturing these machines and Savio company is one of them which produce a

fully automatic machine for spinning industries. In quality point of view, it is a very

good machine and has also very low maintenance cost.

8

Winding department plays an important role in the production and quality of

yarn and causes direct effect on them. The yarn which made in ring section is not

finish yarn and can’t sell to customer. After making the yarn in ring process,

auto cone section made it more even yarn by passing through the optical

sensor and capacitor sensor which is installed in different heads of machine.

The yarn which is obtained from winding section is able to sell the customers.

1.5 Yarn Faults Yarn faults may be defined as yarn irregularities that can lead to difficulties in subsequent production stages, or to defects in fabric.

1.6 Yarn Faults Classification

Figure 1.2: Classification of Yarn

YARN FAULTS

CLASSIMATE

SELDOM OCCURING

RANDOM OCCURING

Physical

COUNT CV

U %

HARINESS

CONTAMINATION

IPI

STRENGTH

PERIODIC

PERIODIC

NON PERIODIC

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1.6.1 Classimate Faults

The position of the frequent yarn faults (imperfections) in comparison to the position of the seldom-occurring yarn faults in the classification matrix are shown in the figure. It becomes clear, that both types of yarn faults differ from each other clearly by their size and thus, cannot be compared with each other. In addition, the areas of the clearer settings N, S, L, T, CCp and CCm are indicated in Fig. This shows where the settings are effective. [16]

Figure 1.3: Classification matrix in Classimat

1.6.2 Deviation in Yarn Quality Faults

COUNT CV

IRREGULARITY

HARINESS

IMPERFECTIONS

STRENGTH

1.6.2.1 Count Variation

This is usually expressed in terms of CV between hank length such as 100 or 50

meter. In case of drawn and spun yarns, long term irregularity arises from variation

either between groups, between bobbins or within bobbins. Between groups

variation represents the difference between spinning frames, frame sides and times

of spinning, whereas between[11][12]

10

Figure 1.4: Effect Of Count Variation On The Fabric Surface

(Combed cotton 100%, Nec 30, Nm 50, 20 Tex)

1.6.2.1.1 Within Bobbins Count Variation

High card sliver & comber sliver U%

High tension draft or improper coils in bobbins variations

Irregular drafting &n stretching on speed frame.

Retching in roving

Use of separator plates at high spindle speeds.

Excessive pinion changes in ring spinning

Defective draw frame is a single major cause for with in bobbins variation,

such as excessive creel or web tension, roller slippage in drawing and

adverse humidity conditions in hair the draw frame drafting leading to within

bobbins variations.

Low humidity

1.6.2.1.2 Between Bobbin Count Variation

Variation in average lap weight over long intervals (e.g. half shift) including

allowance to variation in humidity

High cm to cm variation in lap

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Excessive variation in tuft size

Draft to waste difference between groups of cads or at combers.

Hank differences between D.F slivers

Stretch in the D.F slivers fed to roving

Use of one passage post comber D.F

Row to row differences in hank roving.

Draft differences between roving frame

Marked changes in hank roving over a roving frame bobbins caused by

irregular bobbins speed control

Draft differences between ring frame

Frequent changes of pinion in drawing and ring spinning

Creel draft variation and bobbin holders clogging with waste

Variation in top roller pressure

Variation in bare bobbins diameter

Spindle variation in ring finish

High variation in RH% age

At several stages in spinning process stretch take place and become a source of great

hidden menace as it not only undesirable variation (between bobbins and within

bobbins) but also results in high end breakages excessive wastes and lower the

quality of end product.

1.6.2.2 Yarn Irregularity

All spun yarns are to some extent irregular it is the degree of irregularity which

determines whether it is acceptable or not for a particular end use. Appearance of

many fabrics is influenced by yarn irregularity hence this is frequently regarded as

one the most important yarn characteristics. Yarn irregularity is usually taken to

means the variations of mass per unit length variations in twist and strength and the

diameters are to large extent secondary or tertiary effects of variations in mass per

unit length. Gross variation (yarn faults) are the abnormal variations in the yarn

thickness, Yarns produced from very short fibers may contain short variation in

thickness. Fibers with the greater variation of their diameter have more irregular

yarn.

12

Yarn unevenness is much affected by roving and draft conditions. Long irregularity

is related to fore spinning process of middle roller of ring frame while short term

irregularity mainly process after middle roller of ring frame. Main factors involved

in the formation of short term irregularity are: limited irregularity due to random

fiber arrangement, imperfect fiber control which in roller drafting leads to drafting

waves varying in amplitude and length; and mechanical defects. The pattern of

irregularity in drawn and spun yarn is complex combination of wave length

introduced at each stage of drawing and in spinning. The most important wave is the

one with the shortest wavelength-introduced at the spinning frame. Long term count

variation may be influenced by the no. of doublings used during drawing and

spinning, short term irregularity is hardly influenced by this factor.[13]

There reasons are given below

Faulty roving

Faulty rotation of skewers

Wrong guiding of roving in creel

Chocking of trumpet

Faulty working of traverse bar

Wrong roller setting

Inadequate pressure on top roller

Eccentricity of rollers

Roller lapping & sticking

Defective & worn gears & bearings

Uneven dia. of rubber cots

Non alignment of apron

Worn & damaged aprons

Accumulation of lint under apron

Incorrect gap between aprons

Wider gauge in front drafting zone

Incorrect setting of lappet & spindle

Rough surface of separators

Defective spindles

13

Damaged & worn rings

Light travelers

Close setting of traveler cleaner

Erratic ring rail traverse

The mathematical statistics offer 2 methods to represent yarn irregularity as

following;

1.6.2.2.1 Mean Variation U%

It is the percentage mass deviation of unit length of material and is caused by

uneven fiber distribution along the length of the strand. U% is mostly measure in cut

length of 1 cm that indicated as Um (this is the U value you would have got from

cutting the yarn into approximately 1 cm sections and weighing those short

sections.).The irregularity U% is proportional to the intensity of the mass variations

around the mean value. The U% is independent of the evaluating time or tested

material length with homogeneously distributed mass variation.

1.6.2.2.2 Coefficient Of Variation C.V. %

The standard deviation of the linear densities over which unevenness is measured

expressed as a percentage of the average linear density for the total length within

which unevenness is measured. C.V of irregularity can be measure using following

parameters;[14][15]

CVm: Coefficient of variation of mass with a cut length of approximately 1 cm. This

is the CV most often quoted in yarn specification and commercial transactions.

CVm (1m): Coefficient of variation of mass with a cut length of 1 m, simulating the

CV you would have got from cutting the yarn into 1 m sections and weighing those

sections. The same applies to CVm (10m) and CVm (100m). It should be noted that

as the cut length increases, the irregularity reduces.

1.6.2.3 Yarn Hairiness

Is a measure of the amount of fibers protruding from the structure of the yarn? Yarn

hairiness has many different effects on subsequent processing steps and on the

appearance of woven and knitted fabrics. . [15]

14

During the weaving process, high hairiness can lead to entanglements of

warp threads.

Hairiness is high for low twist and vice versa.

Yarn winding will increase the yarn hairiness whereby the increase will

depend on the raw material, on the yarn twist and on the winding speed.

In uni-colored fabric, hairiness variations exceeding 1.5 between yarns lying

next to each other can be detected by the human eye.

The higher the hairiness, the softer a fabric.

Figure 1.5: Hairiness on the surface of yarn

1.6.2.4 Imperfections (Thin places, Thick places and Neps)

Thin places, thick places and neps are part of yarn unevenness. Deviations of the

mass from the average yarn body exceeding ±50% are counted as thin and thick

places. Neps are short thick places resulting from fiber entanglements of frequently

immature fibers or seed coat fragments. Imperfections in the cross-section of yarn

will heavily increase with higher yarn count, i.e. with fewer fibers in the cross-

section.

The higher the short fiber content, the higher the number of imperfections. Frequent

imperfections can be very disturbing in a fabric. Fiber entanglement often results

from immature fibers which cannot absorb dyestuff and, therefore, remain white.

15

1.6.2.4.1 Thin place (-50%)

Number of places that have mass reductions of 50% or more with respect to the

mean value. Note that (-50%) is the standard sensitivity level used in the test. If a

different sensitivity level (-40%, -40%, -60%) is used, the result would have been

different. These thin places have a length of approx. 40 cm.

1.6.2.4.2 Thick place (+50%)

These are number of places that have mass increases of 50% or more with respect to

the mean value. Note that (+50%) is the standard sensitivity level used in the test. If

a different sensitivity level (+35%, +70%, +100%) is used, the result would have

been different. These thick places have a length of approx. 40 cm.

1.6.2.4.3 Neps (+200%)

Number of places that have mass increases of +200% or more with respect to the

mean value and a reference length of 1mm. Note that +200% is the sensitivity level

normally used in the test. These short thick places in a yarn are often the results of

vegetable matter or entangled fibers.

1.6.2.5 Strength

Yarn strength is measure in tensile strength, which is defined as:-

The variation of maximum tensile strength is a measure for strength variations from

bobbin to bobbin. The causes of lack in fiber strength are

Fiber strength

Fiber growth

Fiber damaging in the spinning process( inadequate roller gauge)

Excessive rubber cots hardness

Excessive top roller pressure

Loose spindle tape

RH%

Singles (when using double roving)

16

Stretched roving due to improper regulation of bobbin speed on roving frame

and

poor handling of roving bobbins during transportation

Excessive twist

Defective piecing

Excessive short fibers content

Use of soft waste on mixing

Roving

1.6.3 Periodic Yarn Faults

The variation in mass per unit length of yarn comprises three basic types, namely (i)

irregularity of a completely random nature, (ii) irregularity of a markedly periodic

nature, (iii) irregularity of a quasi-periodic nature. Purely random irregularity forms

an unavoidable component of total irregularity, so that a minimum achievable

random irregularity can be acceptable for apparel usage. Periodic yarn faults are

thick and thin places, which always occur with the same distance from each other.

Such faults are caused in the spinning process, when yarn guiding elements are

defective. The periodic irregularities which are found in the spun yarns may be the

result of machinery defects such as eccentric drafting rollers, variability in the

covering of drafting rollers, inaccurately cut or worn-out drafting rollers and the

vibration of drafting rollers. Yarns which are affected by any of these defects

occurring in the drafting prior to spinning can appreciably affect the yarn and the

resulting fabric. An eccentric front roller of the ring spinning machine leads to a

periodic fault with a wavelength of 8 cm, as this roller always causes faulty drafts in

the draw-box within the same time intervals. The size of each individual fault is

mostly not disturbing. But as a series of yarn faults, they can very well be disturbing.

In most cases, disturbing periodic faults are formed at the ring-spinning machine.

Widely known are defects caused by cuts and pressure marks on the take-off

cylinder. By this, the continuous distribution of the fibers is disturbed, which results

in thin- and thick places. The size of the fault corresponds to an alteration/shift of all

fibers of about 30-50%. The fault length depends on the dimension of the defective

machine part. The distance between the single events corresponds to the

circumference of the roller, e.g. at the front roller of a draw-box. A further reason for

17

periodic faults can be pressure marks on the top roller. If a spinning position or the

whole spinning frame is stopped and the pressure is not taken from the top roller, it

can lead to pressure marks on the top rollers after longer stops and thus to periodic

defects in the yarn.

Figure 1.6: Difference in periodicity

The distance between the single events corresponds to the circumference of the

cylinders. With soft, even lapping can lead to moiré pattern. Furthermore can a

missing bottom belt rubber coating of the top roller also lead to periodic faults.

There are many possibilities for the origin of periodic defects when spinning

compact yarns. The reasons depend strongly on the spinning method. For regular

ring spun yarns, the reasons are mostly pure mechanical insufficiencies, which lead

to periodic faults in the yarn. For compact yarns, the reasons can be found in the

contamination with fibers and dirt. This dirt can build up for an uncertain time,

which makes it much more difficult to find the reasons. Therefore, the monitoring of

periodic defects in compact yarns is essential.

18

Figure 1.7: Moiré Effect

Mass variation in yarn can adversely affect many properties of textile materials such

as shade variations and strength. Mass variation can be attributed to the properties of

raw materials, inherent short comings in yarn making and preparatory machines,

mechanically defective machinery and/or external causes as a result of working

conditions and improper housekeeping.

Periodic mass variations in yarn can cause weft bars, diamond barring effects, moiré

effects, and weft stripes or rings in the resulting fabric. Hence, periodic irregularity

should not be permitted at all, since it greatly affects the appearance of fabric and

must be controlled. However, the presently available tools used to measure the

periodicity of mass per unit length variation have limitations. The spectrogram is

more reliable compared to other tools for determining periodicity; it works on the

principle of Fourier analysis, which sets out any function in a series of sine curves.

The actual mass variation will be resolved into different sinusoidal waves with

different amplitudes and wavelengths. Hence, spectrogram gives only the resolved

mass variation, which may not be present in the final yarn when different faults are

superimposed.

The spectrogram measures the periodic mass variations in a yarn by analyzing the

frequencies at which faults occur electronically. From the speed at which the yarn is

running the frequencies are converted to wavelengths and slotted into a finite

number of discrete wavelength steps. The result is a histogram as shown in Fig

19

where the amplitude is a measure of the number of times a fault of that repeat length

occurs owing to the fiber length having an effect on the distribution of repeats

around that Length the background level of the spectrogram is not flat but a

periodically repeating fault will show a level much greater than the background as is

shown in the figure. As a general rule the height of a peak in the spectrogram should

not be more than 50% of the basic spectrogram height at that wave length.[10]

Figure 1.8: Amplitude of Periodic Fault

The wavelength of the fault gives an indication of its cause and therefore allows it to

be traced to such mechanical problems as drafting waves, eccentric or oval rollers in

the spinning plant or in earlier preparation stages. The wavelength can also

correspond to the diameter of the yarn package, in which case it will vary between

the full and empty package. The wavelength of a fault that occurs before the drafting

in the spinning process will be multiplied by the drafting ratio.

"DIAGRAM" is a representation of the mass variations in the time domain.

Whereas, spectrogram is a representation of the mass variation in the frequency

domain. Spectrogram helps to recognize and analyze the periodic fault in the sliver,

roving and yarn.

20

Figure 1.9: Normal Mass Spectrogram

For textile application, the frequency spectrum is not practical. A representation

which makes reference to the wavelength is preferred. Wavelength indicates directly

at which distance the periodic faults repeat. The more correct indication of the curve

produced by the spectrograph is the wave-length spectrum. Frequency and

wavelength are related as follows frequency = (wavelength)/(material speed)

In the spectrogram, the X-axis represents the wavelength. In order to cover a

maximum range of wavelengths, a logarithmic scale is used for the wavelength

representation. The y-axis is without scale but represents the amplitude of the faults

in yarn.

The spectrogram consists of shaded and non-shaded areas. If a periodic fault passes

through the measuring head for a minimum of 25 times, then it is considered as

significant and it is shown in the shaded area. Wavelength ranges which are not

statistically significant are not shaded. In this range the faults are displayed but not

hatched. This happens when a fault repeats for about 6 to 25 times within the tests

length of the material. As far as those faults in the un-shaded area is concerned, it is

recommended to first confirm the seriousness of the fault before proceeding with the

corrective action. This can be done by testing a longer length of yarn. Faults which

occur less than 6 times will not appear in the spectrogram. A spectrogram starts at

1.1 cm if the testing speed is 25 to 200 m/min. It starts at 2.0cm if the testing speed

is 400 m/min and it starts at 4 cm if the speed is 800m.min. For spun material the

maximum wavelength range is 1.28 km. Maximum number of channels is 80.

Depending upon the wavelength of the periodic fault, the mass variations are

classified as

Short-Term Variation (wavelength ranges from 1 cm to 50cm)

21

Medium-Term Variation (wavelength ranges from 50cm to 5 m)

Long-Term Variation (wavelength longer than 5 m)

Periodic variations in the range of 1 cm to 50 cm are normally repeated a number of

times within the woven or knitted fabric width, which results in the fact periodic

thick places or thin places, will lie near to each other. This produces, in most cases, a

"MOIRE EFFECT". This effect is particularly intensive for the naked eyes if the

finished product is observed at a distance of approx. 50 cm to 1m.

Periodic mass variations in the range of 50cm to 5m are not recognizable in every

case. Faults in this range are particularly effective if the single or double weave

width or the length of the stretched out yarn one circumference of the knitted fabric,

is an integral number of wave-lengths of the periodic fault, or is near to an integral

number of wave-lengths. In such cases, it is to be expected that weft stripes will

appear in the woven fabric or rings in the Knitted fabric.

Periodic mass variations with wave-lengths longer than 5m can result in quite

distinct cross-stripes in woven and knitted fabrics, because the wave-length of the

periodic fault will be longer than the width of the woven fabric or the circumference

of the knitted fabric. The longer the wavelength, the wider will be the width of the

cross-stripes. Such faults are quite easily recognizable in the finished product,

particularly when this is observed from distances further away than 1 m.

A periodic mass variation in a fiber assembly does not always result in a statistically

significant difference in the U/V value. Nevertheless, such a fault will result in a

woven or knitted fabric and deteriorate the quality of the fabric. Such patterning in

the finished product can become intensified after dyeing. This is particularly the

case with uni-colored products and products consisting of synthetic fiber filament

yarns. The degree to which a periodic fault can affect the finished product is not

only dependent on its intensity but also on the width and type of the woven or

knitted fabric, on the fiber material, on the yarn count, on the dye up-take of the

fiber, etc. A considerable number of trials have shown that the height of the peak

above the basic spectrum should not overstep 50% of the basic spectrum height at

the wavelength position where the peak is available.

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1.6.3.1 Chimney Type Faults:

The eccentricity roller results in a sinusoidal mass variation whereby the periodicity

corresponds to full circumference of the roller. With one complete revolution of an

OVAL roller, a sinusoidal mass variation also results, but 2 periodic faults are

available. Chimney type of faults are mainly due to -mechanical faults -eccentric

rollers, gears etc -improper meshing of gears -missing gear teeth -missing teeth in

the timing belts -damaged bearings etc

Example of a chimney:

Figure 1.10: Example Of Spectrogram Of Chimney Fault

Figure 1.11: Effect of Chimney Fault On Yarn

1.6.3.2 Hill Type Faults:

These faults are due to drafting waves caused by -improper draft zone settings -

improper top roller pressure -too many short fibers in the material, etc numerous

measurements of staple-fiber materials have shown that there are rules for the

correlation between the appearance of drafting waves in the spectrogram and the

mean staple length. It is given below

Yarn: 2.75 x fiber length

Roving: 3.5 x fiber length

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Combed Sliver: 4.0 x fiber length

Draw Frame Sliver: 4.0 x fiber length

A periodic fault which occurs at some stage or another in the spinning process is

lengthened by subsequent drafting. If the front roller of the second draw-frame is

eccentric, then by knowing the various drafts in the further processes, the position of

the peak in the spectrogram of the yarn measurement can be calculated. The

wavelength of a defective part is calculated by multiplying the circumference of the

part and the draft up-to that part. The wavelength of a defective part can be

calculated if the rotational speed of the defective part and the production speed are

known. Doubling is no suitable means of eliminating periodic faults. Elimination is

only possible in exceptional cases. In most cases, doubling can, under the best

conditions, only reduce the periodic faults. The influence of periodic mass variation

is proportional to the draft. Due to the quadratic addition of the partial irregularities,

the overall irregularity of staple-fiber yarns increases due to the periodic faults only

to an unimportant amount.

1.6.3.2.1 Drafting Faults

Another type of irregularity which is clearly visible in spectrograms is a drafting

fault. It is an exaggerated crest (hill) which results from poor fiber control in a

drafting zone.

Figure 1.12: Example of Spectrogram of hill type periodic Fault

Drafting faults are created and influenced by non-optimal settings of one or several

of the following factors:

- Gauge distance between the drafting rollers (Nip)

- Roller Pressure

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- State of the roller’s surfaces

- Humidity of material and surrounding climate

When searching to eliminate drafting faults, one would look for the main cause in

one of those factors first. In many cases though, a compromise has to be found, since

certain materials are more critical. Example: Combed cotton draw frame slivers,

where the fibers are highly parallel and thus slippery and difficult to draft optimally

at a reasonable speed. A drafting fault hill is to be found at a wavelength of about

2.8 × average fiber length. If the drafting fault hill does not lie around 2.8 × average

fiber length, one has to divide the wavelength λ of the hill crest by 2.8 × average

fiber length in order to get the approximate draft factor back to the origin of the

fault.

Formula:

1.6.3.3 Multiple Periods

In very many cases, a single periodic material fault produces multiple chimneys.

Multiple chimneys are the result of a periodic yarn mass variation which is not

evenly shaped, i.e. not sine-shaped. A multiple periodic fault consists of a base

wavelength and of so-called harmonic wavelengths. The harmonics are usually to

be found at factor 1/2, 1/3, 1/4, etc. of the base wavelength.

Example:

lengthfiberaverageratioDraft cresthill

8.2

25

Figure 1.13: Spectrogram and Yarn Board Image of a Bad OE Yarn.

The 10cm moiré was caused by a dirty Rotor groove.

The reason for the appearance of multiple chimneys lies in the behavior of wave signals. Mathematically, it is complex (Fourier transformation), but graphically, it becomes quite evident:

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Chapter: Materials and Method -------------------------------------------------------------------------------------------------------------------------

2.1 Material Four outputs from Breaker, Finisher, Roving and Ring were chosen as raw material

for investigation of periodic yarn faults. These products were processed on the

standard spinning machinery with Pakistani Cotton. The properties of this cotton are

given in the table.

Table 2.1: The Properties Of Cotton

Parameter Mean Cotton Type Carded Combed SCI 126.69 132.75 Mic 4.35 4.64 Mat 0.88 0.9 Length (Inch) 1.078 1.106 Unf. 82.66 83.5 SFI (%) 7.61 7.14 Str. (g/tex) 29.81 31.01 Trash 7.77 6.91 Moist. (%) 8.84 9.12 Rd. 72.61 73.52 +b 8.66 8.23

All samples from breaker sliver, finisher sliver, simplex roving and ring yarn were

prepared in “Fazal Cloth Mills, Unit # 4” by using Automatic Bale Opener Blow room

setup of Trutzschler Company, Trutzschler TC-03 card, Draw frame breaker Reiter

Rsb-2, Finisher Reiter RSB-D 40, speed frame Fl-100 and ring frame RX-240. The

sequence of machines is shown in the figure 2.1. Parameter, that were used for the

preparation of breaker sliver, finisher sliver, simplex roving and ring yarn on each

machine are in the Table 2.2.

The linear densities of the prepared breaker sliver, finished sliver, and roving were

68 grains/yard, 65 grains/yard, and 0.74 hanks respectively. Yarn samples of and

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21/1 Nec were prepared from rovings at a spindle speed of 21500 rpm with a twist

multiplier of 3.75 respectively.

Figure 2.1: Sequence of Machines for Yarn Preparation

Table 2.2: Parameters Used In the Experiments

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2.2 Method Before testing, all the prepared yarn samples were conditioned in the laboratory

under standard atmospheric conditions of 21±1°C and a relative humidity of 65±2.

The periodic faults at breaker sliver, finisher sliver, simplex roving and ring yarn

were investigated and analyzed and rectified by following steps.

1. Identify the periodic fault length by mass spectrogram.

2. Analysis the gearing system

3. Identify origination point of yarn fault

4. Rectification of yarn faults

2.2.1 Identify the Periodic Fault Length By Mass Spectrogram

When sliver, roving or yarn is tested by UT-4, it provides us mass spectrogram of

material. In the spectrogram, the X-axis represents the wavelength. In order to cover

a maximum range of wavelengths, a logarithmic scale is used for the wavelength

representation. The y-axis is without scale but represents the amplitude of the faults

in yarn.

Figure 2.2: Spectrogram Representing Periodic Fault

The spectrogram consists of shaded and non-shaded areas. If a periodic fault passes

through the measuring head for a minimum of 25 times, then it is considered as

significant and it is shown in the shaded area. Wavelength ranges which are not

statistically significant are not shaded. In this range the faults are displayed but not

hatched. This happens when a fault repeats for about 6 to 25 times within the tests

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length of the material. As far as those faults in the un-shaded area is concerned, it is

recommended to first confirm the seriousness of the fault before proceeding with the

corrective action. This can be done by testing a longer length of yarn. Faults which

occur less than 6 times will not appear in the spectrogram.

2.2.2 Analysis the Gearing System

Gearing diagrams and their relative wavelengths are analyzed by using following

principle. Suppose a machine have following diagram.

Figure 2.3: Drafting Elements of a Ring Spinning Machine with Gearing Drive

Periodicity of front roller (λ 1) = λ 1 = DFR x π = 2.54 x π ≈ 8 cm

Periodicity of Z2 Gear = λ2 = λ1 x ౖమౖభ = 8 x ଵଶଵ

ଵଵ = 88 cm

If the gear Z3 is defective, then the effect in the fiber material is the same as that

produced with the gear Z2, because both gears are on the same shaft.

Periodicity of Z4 Gear = λ3 = λ1 x ౖమౖభ

x ౖరౖయ = 8 x ଵଶଵ

ଵଵ x ଽ

ଷ = 8.33 = 264 cm

= 2.64 m

The front roller, therefore, turns 33 times until the defect at Z4is repeated. A defect

of the gear Z4 directly affects the back roller BR because this gear is on the same

shaft. The influence on the back roller, multiplied by the total draft, results in the

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same wave-length as the influence of Z4on the front roller: Circumference of the

back roller

UBR = DBR x π = 2.54 x π ≈ 8 cm

Wave-length at the output of the draw-box: λ 4 = UBR x Vtot = 8.33 = 264 cm

= 2.64 m

Here, Vtot = total draft

A defect of the gear Z4 affects the middle roller MR in the following manner

(Z4 and Z5 are on the same shaft):

λ`5 = UMR x ౖలౖళ

x ౖఱౖల = 2.3 x π x ଶ

ଶ x ଷଶ

ଶ = 8.89 cm

Wave-length at the output of the draw-box: λ5 = D2 x λ`5 = 29.6 x 8.89 ≈ 263cm

= 2.63 m

So, using above principle, we analyze the gearing systems of Breaker, Finisher,

Simplex and Ring. The gearing diagrams along with wave length of each part are

given below.

2.2.3 Identify Origination Point of Yarn Fault

When searching the origin of the periodicity, the first step is to remember that the

fault is caused by a moving machine part, usually a rotating one. It can be directly

touching the material (rollers, coiling, etc.) or in the machine drive (gears, pulleys,

etc.). By using above analysis, location of periodic fault is identified by comparing

the wave calculating from the gearing system with mass spectrogram.

2.2.4 Rectification of Yarn Faults

Once the yarn fault and defective part is localized, then that defective part is

replaced by taking suitable measures or it is eliminating from the yarn by using

classimate setting termed as PC.

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Chapter: Results and Discussion -------------------------------------------------------------------------------------------------------------------------

3.1 Investigation and Rectification of Periodic Faults at Breaker

3.1.1 Identify the Periodic Fault Length By Mass Spectrogram

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Figure 3.1: Gearing Diagram of Drawing Breaker

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Table 3.1: Periodic Fault lengths of Different Parts of Breaker


As you can see from the spectrogram chart peak of unacceptable length is shown in red color approximately at 61~62cm, which cause periodic variation in yarn and can create difficulties in subsequent processes. On the basis of analysis of the gearing system, λd2 is the faulty middle roller which produces this peak.

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When medium roller was checked, there was a cut in the top medium roller. So,

medium roller was changed and hence fault was removed. And UT4 report after

removal of fault is given below.

Hence it proves that our periodic fault detection system was working properly.

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3.2 Investigation and Rectification of Periodic Faults at Finisher

3.2.1 Identify the periodic fault length by mass spectrogram

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Figure 3.2: Gearing Diagram of Drawing Finisher

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Table 3.2: Periodic Fault lengths of Different Parts of Finisher

3.2.3 Identify Origination Point Of Yarn Fault

From this fig it is seen clear that peak is higher than acceptable limits so by matching the values of spectrogram with PERIODIC FAULT DETECTION SYSTEM. We can compare the value of λ. By comparing it is noted that this peak is equal to λ NW1 (58.206 cm). Peak which shows that λNW1 gear is faulty.


When gearing system was checked, there was a problem in λNW1. So, λ NW1 was

changed and hence fault was removed. And UT4 report after removal of fault is

given below.

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3.3 Investigation and Rectification of Periodic Faults at Simplex

3.3.1 Identify the Periodic Fault Length by Mass Spectrogram

40


Figure 3.3: Gearing Diagram of Simplex Fl-100

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Table 3.3: Periodic Fault lengths of Different Parts of Simplex Fl-100

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From this fig it is seen clear that peak is higher than acceptable limits so by matching the values of spectrogram with PERIODIC FAULT DETECTION SYSTEM. We can compare the value of λ. By comparing it is noted that this peak is equal to λ d(36 tooth gear of Simplex). Peak which shows that λd gear is faulty.


When roller in the gearing named as d roller was checked, there was a damaged tooth in that roller. So, roller was changed and hence fault was removed. And UT4 report after removal of fault is given below.

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3.4 Investigation and Rectification of Periodic Faults at Ring

3.4.1 Identify the Periodic Fault Length by Mass Spectrogram

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Figure 3.4: Gearing Diagram of Ring Frame RX-240

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Table 3.4: Periodic Fault lengths of Different Parts of Ring Frame RX-240

3.4.3 Identify Origination Point Of Yarn Fault

From this fig it is seen clear that peak is higher than acceptable limits so by matching the values of spectrogram with PERIODIC FAULT DETECTION SYSTEM. We can compare the value of λ. By comparing it is noted that this peak is equal to λFR (Front Roll in the Ring). Peak which shows that λFR gear is faulty.

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When front roller was checked, there was a cut in the top front roller. So, front roller was changed and hence fault was removed. And UT4 report after removal of fault is given below.

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Conclusions

In this work, periodic yarn fault detection system was developed. It is suitable for

identifying the source of periodic fault on the machine. It was developed because

spectral analysis of machines with complex driving systems requires time and work-

consuming calculations, which make it considerably more difficult to quickly find

the cause of the detected periodicity in the stream of fibers. The result shows that

this system is helpful to eliminate periodic yarn faults of breaker, finisher simplex

and ring machines.

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[11] T. P. A. T k Pattabhiram, Essential Facts Of Practical Cotton Spinning.

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[14] USTER®, “Description of all quality parameters measured by Uster

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Investigation Periodic Faults in Yarn

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