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1.1 Introduction

This project work covers the different technical and theoretical aspects, related literature

reviews, experimental findings and their both tabular and graphical representations,

technical explanations and result analysis from our work termed ‘Impact of different

clearing limits of yarn clearer on yarn quality and productivity‘. For all known spinning

methods of today it is necessary to have a yarn monitoring system in the last production

process of the spinning mill, which stops the production position if disturbing faults

occur. The machine must automatically remove the faults and replace it by a splice. The

spinning process is not a perfect process and can produce imperfections. Another source

for irregularities in ring spinning is the availability of flies in the air which are frequently

spun into the yarn and accumulations of fibre fragments and dust at yarn guiding

elements. In ringframe, all fibre and yarn guiding elements, ring traveler, pressure rollers,

belts and spindles can contribute to yarn faults, particularly if there are defective.

Therefore, one important rule of modern quality management cannot be implemented

completely: ―Preventive actions rather than corrections afterwards!‖

With the help of yarn clearer such as Uster Quantum 2, Loepfe Zenith etc. we can remove

different types of prominent yarn faults thus improving quality of yarn.

1.2 Objectives

To study about different yarn clearing systems and clearing limits from literature.

To analyze various types of yarn faults.

To process ring yarn of same specifications under three different clearing limits in

Uster Quantum 2 and observe the resultant cut data.

To analyze yarn quality and characteristics before and after winding.

To study the effects of the three different yarn clearer settings on productivity and

wastage generation in winding machine.

.

Impact of different clearing limits of yarn clearer on yarn quality and productivity Page 2

Chapter 2

Literature Review


2.1 Yarn clearer

The device which is used to remove faults (thick places, thin places, foreign matter) from

the yarn is known as yarn clearer. Yarn clearing improves the quality of the spun yarn and

hence of the cloth made of it.

Yarn clearing is usually part of the yarn winding process. The yarn from a number of

spinning bobbins, called 'cops', is wound on to larger packages called 'cones' for

subsequent processing into fabric. During the winding the yarn was traditionally passed

through the narrow slit in a steel plate of a yarn clearer or slub-catcher. The object was to

catch thick places, or slubs, which occurred when the spinning process suffered an

aberration, and to prevent them being woven into the fabric to present unsightly faults.

In modern textile industry, after detecting the faults, the clearer cuts the faulty pieces

from the yarn, and after that the piecing device joins the cut ends. [1]

2.2 Types of yarn clearer

There are two types of yarn clearer

1. Mechanical type

Conventional blunt type

Serrated blade type2. Electronic type

Capacitance type

Optical type

2.2.1 Mechanical type

A mechanical clearer maybe as simple as two parallel blades. The distance between the

blades is adjustable to allow only a predetermined yarn diameter to pass through. A

thicker spot on the yarn (slub) will cause the tension on the yarn to build up and

eventually break the yarn. Consequently, this type of device can only detect thick places

in the yarn. [2]

2.2.2 Electronic type

Electronic yarn clearers ensure excellent clearing to be obtained with minimum

mechanical stress on the yarn. In order to be able to monitor and to evaluate thick and

thin places as well as deviations from the desired yarn count, the thickness of the yarn

must be converted into a proportional electrical voltage. The course of voltage is called


yarn signal. This conversation is carried out either with the sensor of the capacitive

measuring principle or with the sensor of the optical measuring principle.

The capacitive measuring principle

The electrical measuring condenser (1) forms the sensor for the capacitive monitoring of

the yarn mass. This is done by two parallel metal plates, the electrodes. In the space in

between (2), the two electrodes build an electrical field when putting on an electrical

alternating voltage (3).

Figure 2.1 Capacitive sensor

If a yarn (4) is brought into this field, the capacitance of the measuring condenser is

changed. From this change, an electrical signal, the yarn signal is (5) is derived. The

change in the capacitance depends, besides of the mass of the yarn and of the dielectric

constant of the fibre material is used, on the moisture content of the yarn.

With the capacitive measuring principle, the yarn signal corresponds to the yarn cross-

section and yarn mass respectively, which is located in the measuring field. Changes of

the yarn mass cause a proportional change of the yarn signal.

The optical measuring principle

The infrared light source (1) and the photocell (3) represent the sensor for the optical

monitoring of the yarn thickness. The infrared is light is scattered by a diffuser (2) in the

light field and reaches the photocell (3). The photocell emits a signal, which is

proportional to the amount of light.


Figure 2.2 Optical sensor

If a yarn (4) is brought in the light field, parts of the light will be absorbed by the yarn.

The amount of light, which hits the photocell, is smaller. From this change, an electrical

signal, the yarn signal (5) is derived.

With the optical measuring principle the yarn signal corresponds to the diameter of the

usually round yarn, which is located inside the measuring field. Changes of the yarn

diameter cause a proportional change of the yarn signal. [3]


Table 2.1 Comparison between capacitive and optical principle

Property Capacitive principle Optical principle

Yarn signal Corresponds to the Corresponds to the diameter

mass/cross section of the of the yarn and the visual

yarn or the number of fibres impression.

in the measuring field.

Effective measuring field The current yarn signal is The current yarn signal is

length: different measuring the mean value of the piece the mean value of the piece

field lengths influence the of yarn which is located in of yarn which is located in

monitoring of very short the measuring field. the measuring field. Length:

yarn faults. Length: 7 mm 3 mm

Evaluation of the yarn fault

Normal yarn fault The fault is evaluated with The fault is evaluated with

the full increase of the the full increase of the

cross-section in percent. diameter in percent.

Voluminous, visually large As the number of additional The very voluminous yarn

appearing yarn fault fibres is not extremely high, fault absorbs a lot of light.

this yarn fault is considered Therefore, the fault is

as relatively insignificant. considered as significant.

Short yarn faults, length: 3 The increase of the diameter The fault is evaluated with mm

of this short fault is the full increase of the

averaged over the whole diameter.

measuring field length. The

fault is only evaluated as

half of the size.

Very compact yarn fault The fault is evaluated with Compact yarn fault absorbs

the full increase of the small amount of light.

cross-section. Due to the Increase of the diameter is

The distance between two higher number of fibres considered as insignificant.

white lines is 1 cm. thick place absorb more

dye.


2.3 Comparison between mechanical and electronic type

Electronic clearer are more sensitive than mechanical clearers.

In case of mechanical clearers there is abrasion between yarn and clearer parts

but in case of electronic clearers there is no such abrasion.

Mechanical clearers do not prevent soft slub from escaping through clearer

where as electronic type does not allow passing of any types of faults.

Mechanical type does not break the thin places and the length of the fault is not

considered.

Mechanical clearer are simple and easy to maintain while the electronic clearers

are costly and requires high standard of maintenance. [4]

2.4 Development of yarn clearer

In 1960 Zellweger Uster launched the first electronic yarn clearer, the USTER®

SPECTOMATIC. With one single, central setting it could be determined, from which size

on a thick place should be cut. Once on the market, the demands for the yarn clearer rose

steadily. Since then, Zellweger Uster could always fulfill the demands of the customers to

their full satisfaction with innovative clearer models.

Figure 2.3 Uster clearer generations and their functions


2.5 Intelligent measuring head

In order to be able to monitor and to evaluate thick and thin places as well as deviations

from the desired yarn count, the thickness of the yarn must be converted into a

proportional electrical voltage. The course of the voltage is called yarn signal.

In the USTER® QUANTUM CLEARER, the conversion is carried out either with the

sensor of the capacitive measuring principle or with the sensor of the optical measuring

principle. The sensor is part of the intelligent measuring head iMK which also consists of

the electronic system to convert mass or diameter variations into an electric signal.

Figure 2.4 Intelligent measuring heads iMK (yarn clearer)

There are very high demands for both measuring principles regarding the resolution and

precision of the results. The sensor must be able to monitor a yarn which runs with up to

120 km/h through the sensor and to detect even very short faults.

2.6 Types of yarn faults

The principles of the spinning process for short-staple and long-staple yarns remained

same for many decades. Changes took place especially in the field of automation and

production quantity per production hour in order to reach the highest production of yarn

in a good quality at the least expenses for personnel, capital and energy. For this, big

technological progresses in each process stage were essential. Despite this progress and

many years of experience in spinning technology, it is still not possible to produce a fault-

free yarn straight-off. Depending on the raw material and state of the machinery park,

there are about 20 to 100 events over a length of 100 km yarn, which do not correspond to

the desired appearance of the yarn. This means, that the yarn exhibits a yarn fault every 1

to 5 km. These kinds of yarn faults are places, which are too thick or too thin. Foreign

fibres or dirty places in the yarn are also counted as yarn faults.


Figure 2.5 Yarn faults

2.6.1 Seldom occurring faults and frequently occurring faults

During the spinning process, a card sliver with about 20,000 to 40,000 fibres in the cross-

section is drawn to a yarn with about 40 to 100 fibres in the cross-section. During the

spinning process it is not possible to keep the number of fibres in the cross-section

constant at every moment.

This leads to random variations of the mass. Only spinning mills with a permanent

improvement process are able to keep these random variations within close limits. These

variations are measured by the evenness tester in the laboratory. They are a measure for

the unevenness of the yarn and are called imperfections. They occur so frequently that

they are not eliminated from the yarn. Their number is generally given per 1000 m. In

contrast to the frequent yarn faults, there are also the seldom-occurring yarn faults. The

difference between the frequent yarn faults and the seldom-occurring yarn faults is mainly

given by the larger mass or diameter deviation and size. As these faults occur only

seldom, their number is given per 100,000 m. These faults are monitored by the USTER®

CLASSIMAT or by the clearer installation on the winding.


Figure 2.6 Area of frequent and seldom occurring faults

2.6.2 Distinction between frequent and seldom-occurring yarn faults

Fig. 2.7 shows the position of the frequent yarn faults (imperfections) in comparison to

the position of the seldom-occurring yarn faults in the classimate matrix. 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. 2.7. This shows where the settings are effective.

Figure 2.7 Position of the frequent versus seldom occurring yarn faults


Causes for seldom-occurring yarn faults

The causes for seldom-occurring yarn faults can be divided in three groups:

1. Caused by raw material and card 2. Caused by the processes before spinning 3. Caused by the spinning process

The distribution of the faults can be found in the classification matrix (Fig 2.8) as follows:

Figure 2.8 Causes for seldom-occurring yarn faults in the classification

Yarn faults caused by raw material and card

These faults depend on the quality of the raw material. For natural fibres, they depend

mainly on the physical properties such as fibre fineness, length and short fibre content.

For synthetic fibres, the faults depend mainly on the disentanglement of single fibres.

Insufficient disentanglement can lead to felted single fibres, which might be caused by

softeners, oil additives, lubricants or climatic conditions.

Yarn faults caused by processes prior to spinning

These faults are characterized by extreme diameter variations or poor friction of the

fibres. Often, it is a matter of fibre packages, which are not caught in the draw-box of

prior processes and were not drawn apart. Therefore, they show a big increase of the mass

or diameter in the yarn.

Yarn faults caused in spinning

Most yarn faults are caused by spun-in fly in the area of the spinning machine and by

fibre residues, which cling to the draw-box or other parts of the spinning machine and

which are swept away from time to time and are spun into the yarn. Furthermore, it is

possible that different setting possibilities of the ring spinning machine, as e.g. draft or

distance settings of the draw-box, have an influence on the number of seldom-occurring

yarn faults.


2.7 Effect of seldom-occurring yarn faults

The faults in the region of C3, C4, D3 and D4 of Classimat matrix are particularly weak in

terms of tensile strength, elongation, and abrasion to sustain the stress of further

processing. Though presence of A3 and A4 does not affect strength and elongation of yarn

but these faults are visually disturbing. [5]

2.8 Yarn clearer settings

The yarn clearer has to be provided with certain basic information in order to obtain the

expected results in terms of clearing objectionable faults. The following are some of

them

2.8.1 Clearing limit

The clearing limit defines the threshold level for the yarn faults, beyond which the cutter

is activated to remove the yarn fault. The clearing limit consists of two setting parameters – Sensitivity and Reference length.

i. Sensitivity – This determines the activating limit for the fault cross sectional size. ii. Reference length – This defines the length of the yarn over which the fault cross –

section is to be measured. Both the above parameters can be set within a wide range of

limits depending on specific yarn clearing requirements.

2.8.2 Yarn count

The setting of the yarn count provides a clearer with the basic information on the mean

value of the material being processed to which the clearer compares the instantaneous

yarn signals for identifying the seriousness of a fault.

2.8.3 Material number

Besides the yarn count there are certain other factors which influence the capacitance

signal from the measuring field like type of fibre (Polyester / Cotton / Viscose etc.) and

environmental conditions like relative humidity. These factors are taken into

consideration in the ‗Material number‘.

2.8.4 Winding speed

The setting of the winding speed is also very critical for accurate removal of faults. It is

recommended that, instead of the machine speed, the delivery speed be set by actual

calculation after running the yarn for 2-3 minutes and checking the length of yarn

delivered. Setting a higher speed than the actual is likely to result in higher number of


cuts. Similarly a lower speed setting relative to the actual causes less cuts with some

faults escaping without being cut. In most of the modern day clearers, the count, material

number and speeds are monitored and automatically corrected during actual running of

the yarn. [6]

2.9 Fault channels

The various fault channels available in a latest generation yarn clearer are as follows:

1. Thick places 2. Thin places 3. Count variations 4. Periodic yarn faults 5. Foreign fibres 6. Vegetable filter

2.9.1 Monitoring of thick place

Staple fibre yarns show a random distribution of the mass. Reasons for their origin are

diverse. Starting at a certain size (mass or diameter and length) this unevenness will be

disturbing in the yarn. Electronic yarn clearing is a process in which disturbing yarn faults

are detected and eliminated. In ring spinning, yarn clearing is carried out on winding

machines with a winding speed of up to 2500 m/min.

Yarn monitoring and yarn clearing is based on the mean value of the yarn. This yarn

value is determined by the measuring head itself. This is valid for the capacitive as well

as for the optical measuring head.

Definition of the yarn body

Under the expression "yarn body" it is understood that the nominal yarn with its tolerable,

frequent yarn faults. Fig 2.9 shows a scatter plot with the marked area of the yarn body in

comparison to the area of the disturbing yarn faults.


Figure 2.9 Course of the yarn body

The green shaded area represents the yarn body and becomes bigger in the direction of the

short yarn faults. This is due to the fact that a short yarn fault with a significant mass or

diameter deviation is considered as disturbing by the eye as a long yarn fault with little

deviation. Short faults also occur more often. If the clearing limit is set within the green

shaded area, the number of clearer cuts increases considerably.

Classimate matrix

Seldom-occurring yarn faults are classified in the classification matrix of the USTER®

CLASSIMAT. Besides the classification matrix, the cut thick places are divided in three

groups (Fig 2.10):

Figure 2.10 Classification system for the settings N, S and L


N – faults: thick places from 2 mm to 1 cm - neps

S – faults: thick places from 1 cm to 8 cm - short thick places

L – faults: thick places over 8 cm - long thick places

2.9.2 Monitoring of thin places

Thin places, as long as they don't lead to yarn breaks, are only disturbing starting from a

certain length. The reason for disturbing thin places is mostly missing fibre material. The

monitoring of thin places is done with the T-channel.

Figure 2.11 Clearing limit for the T-channel

2.9.3 Monitoring of yarn count deviations

Deviations of the yarn count within a yarn lot lead to high costs for complaints. The fact

that the faulty yarn deviates over several meters or even longer from the nominal count

can cause quality problems in the end product. The reasons for count variations are

diverse:

• Deviations by mixing in wrong bobbins. • Peeled-off or uneven rovings can lead to varying counts within a bobbin. • Missing of a fibre component can also lead to count variations.

This demands a reliable monitoring of the yarn count on one side, but also its precise

setting, which is in accordance with the quality requirements of the yarn. This can be

done in many ways. In the following, two possibilities are described:

The C-channel monitors the yarn count in the start-up phase after the splicing

process. During this phase, mainly bobbins with the wrong count are registered

and the winding position must be stopped with the corresponding alarm

functions. After the start-up phase, the C-channel is not active anymore. This

procedure allows the choice of very sensitive settings, which are adjusted to the

special circumstances of the start-up phase of the winding position.


The CC-channel monitors the yarn count over the whole winding process. The

monitoring of yarn count deviations at the normal winding speed are much better

than during the start-up phase. Therefore, it is also possible to monitor long yarn

faults with the CC-channel dependent on the choice of the settings.

Figure 2.12 Clearing limits N, S, L, T, Cp, Cm, CCp and CCm

2.9.4 Monitoring of periodic faults

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. 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. Periodic yarn

faults are known as ring spinning moiré.


Figure 2.13 Taper board with moiré pattern

Periodic fault registration with the PC – channel

Periodic yarn defects cannot be detected with the normal settings of a yarn clearer, as the

size of each individual fault lies far below the adjustable clearing limits. With the

USTER® QUANTUM CLEARER such periods can be detected with the Pearl Chain

channel (PC).

Description of the functions of the Pearl Chain-channel

The thick place which is created by the alteration of the fibres, serves as the threshold in

the PC-channel. The following four parameters have to be fulfilled for a cut according to

the PC-channel.

• Sensitivity (%) = min. fault size • Length (cm) = min. fault length • Fault distance (cm) = distance from yarn fault to yarn fault • Number of faults = number of faults until cut takes place

With the two parameters sensitivity (%) and length (cm), the tolerable fault size is

entered. With the setting "fault distance", the length between the single periods is entered.

The entered distance should be at least 10% longer than the determined value.

Furthermore, the setting must be adjusted to the iMK-type. If the settings are exceeded

once, all following events are counted with the set fault distance. After reaching the given

number of faults ("number of faults"), a cut follows or a PC-alarm is triggered.


2.9.5 Monitoring of foreign materials

Origin of foreign fibres in cotton

Cotton can be contaminated with foreign material from the cotton field to the spinning

mill in different ways. Already during harvesting, materials like e.g. plastic, human and

animal hair, feathers, strings, packing material, stems, leaves and oil contamination can

get into the cotton. When processing the cotton in the gin, it is exposed to another

possible source of foreign fibre contamination. Especially packing material, like covers,

plastic bags, foil and jute gets into the cotton. Furthermore, in the gin there is the risk that

already existing foreign material gets torn into pieces. As a result, the number of foreign

material pieces increases and the detection in the following process gets more difficult.

The processing in the spinning mill can add more foreign fibres to the cotton as well.

They derive especially from rests of packing or cleaning material, which are used for

maintenance.

Measuring principle and evaluation

For the monitoring of foreign fibres, an optical measuring system is used. For this, a

comparison between the reflection of the foreign fibre and the normal yarn color is carried

out. This means, that a very dark foreign fibre in a very light yarn produces a higher

contrast than the same foreign fibre in a yarn made out of gray fibres. After each cut, the

yarn clearer adjusts itself on the white background of the measuring field, in order to

adjust afterwards on the actual color of the yarn. Then, the difference between the actual

yarn color and the contrast of a foreign fibre and its length, over which the color change

occurs, is measured. These two values (reflection in % and length in cm) are compared

with the set clearing limits. Are both values above the clearing limit, a cut is carried out.

Foreign fibres which do not exceed the clearing limit are entered in the classification

matrix.

Structure of the classification matrix

Fig 2.14 shows the structure of the classification matrix for foreign fibres. The foreign

fibres are classified by the parameters reflection (%) and length (cm).


Figure 2.14 Structure of the classification matrix for foreign fibres

In order to meet the demands of critical products, the clearing limit should be selected in

such a way that the B1 class for foreign fibres is cut. The B1 class in the USTER®

Foreign class system covers the foreign fibres with a length from 10 to 20 mm and a

reflection of 5 to 10%. This fault category occurs quite frequently and is also a criterion,

if the measurement on the machine is stable.

Clearing limits for dark foreign fibres in light yarn

The FD-channel (Foreign matter Dark) is responsible for the clearing of dark foreign

fibres in light yarn. A dark foreign fibre has a low light reflection and therefore appears

darker than the yarn.

For dark foreign fibres in a white yarn:

0% = Reflection of the pure yarn

100% = Reflection of a completely black foreign fibre

Clearing limits for light foreign fibres in dark yarn

The FL-channel (Foreign matter Light) is responsible for the clearing of light foreign

fibres in dark yarn. Light foreign fibres have a high light reflection and therefore appear

lighter than the yarn.

For light foreign fibre in a black yarn:

0% = Reflection of the pure yarn

100% = Reflection of a completely white foreign fibre


2.9.6 Vegetable filter

Purpose of the vegetable filter

The sensor of the USTER® QUANTUM CLEARER does not only recognize foreign

fibres as disturbing faults, but also vegetables. Some of the customers are also interested

to eliminate vegetables, but many customers are eager to only remove real foreign fibres

because they can prove that the vegetables are not visible anymore after bleaching.

Zellweger Uster has developed a tool for the USTER® QUANTUM CLEARER to

separate foreign fibres and vegetables. This feature is named Vegetable Filter.

The elimination of foreign fibres only and keeping as much vegetables in the yarn as

possible can be applied for the following purposes:

Reduction of cuts while keeping the eliminated number of foreign fibres constant

Keeping the number of cuts constant but eliminating more and finer foreign fibres

with the same efficiency

Distribution of vegetables and foreign fibres

In order to differentiate between vegetables and foreign fibres, different possibilities

were tested. The chosen approach was:

• A fine foreign fibre has a low reflection and a low mass • A coarse foreign fibre or a bundle of foreign fibres has a high reflection and a

considerable mass

Thus, there is a physical law between the reflection and the mass of foreign fibres, which

is shown in Fig. 2.15. Therefore, foreign fibres can be expected between the red line and

the zero line. Vegetables, in contrast, are spread in the whole green zone (Fig. 2.15).


Figure 2.15 Distribution of foreign fibres and vegetable matter in a yarn

Fig. 2.15 shows the capacitive signal versus the reflectance signal. It is indicated, where

the foreign fibres or foreign fibre bundles can be expected. The capacitive signal depends

on the diameter of the foreign fibre, the number of parallel foreign fibre, the density and

the dielectric constant.

As shown in Fig. 2.15, the Vegetable Filter cannot completely separate foreign fibres and

vegetable matter, but the effect on the clearing performance can be considerable. The

Vegetable Filter was developed so far for the capacitive clearer only.

2.10 Winding

Ring spinning produces yarn in a package form called cops (cop is a slightly tapered

cylindrical tube onto which a yarn is wound during ring spinning. It also may be called a

ring tube, yarn bobbin, or spinning bobbin.) Since cops from ring frames are not suitable

for further processing, the winding process serves to achieve additional objectives made

necessary by the requirements of the subsequent processing stages.

Following are the tasks of winding process

Extraction of all disturbing yarn faults such as the short, long thick, long thin,

foreign contamination etc.

Manufacture of cones having good drawing - off properties and with as long a

length of yarn as possible.


Waxing of the yarn during the winding process.

Production of the yarn of a minimum number of splice.

Achievement of a high machine efficiency i.e. high production level.

The winding process therefore has the basic function of obtaining a larger package from

several small ring bobbins. This conversion process provides one with the possibility of

cutting out unwanted and problematic objectionable faults. The process of removing such

objectionable faults is called as yarn ‗clearing‘. [7]

2.10.1 Acceptable deterioration in quality from ring bobbin to cone

During clearing and winding of yarn, it has been practically experienced by industry that

there is deterioration of certain yarn characteristics like strength, elongation, hairiness,

etc. Irregularity can adversely affect many properties of textile materials. There is

deterioration in terms of U% and IPI values and hairiness from ring frame bobbin to cone

due to abrasion of yarn with various contact points in yarn path.

2.10.2 Factors influencing process efficiency of automatic winding machine

The achievement of expected process efficiency in winding department is a challenging

task for any spinning technician. The process efficiency of winding is influenced by

several factors mentioned as follows:

Winding speed

Number of yarn splicing or knotting per 10,000 m

Rate of yarn breakage

Spinning bobbin mass

Waiting time

Timing for manual doffing

2.10.3 Winding speed

The winding speed has a significant impact on the quality of the yarn as well as

productivity of winding process. Higher winding speed put more stress and strain on the

yarn and also increases degree of abrasion with different machine parts. The winding

speed has a predominant effect on yarn properties such as imperfections, hairiness,

tenacity, etc.


2.10.4 Yarn tension

Yarn tension plays a very important role in deciding the quality and efficiency of textile

processes. Variation in yarn tension affects the physical properties of the produced yarn,

such as its tensile strength and elasticity, and as such its stress-strain characteristics.

Tension control is an important aspect in the modern cone winding machine to control

yarn breakages. [8]

Figure 2.16 Zones of winding machine Impact of different clearing limits of yarn clearer on yarn quality and productivity Page 24

2.10.5 Zones of winding machine

In the unwinding zone, yarns are unwound from the supply package which is ringframe

bobbin in most of the cases. Yarn balloon is formed due to the high speed unwinding of

yarn from the supply package. Unwinding tension varies continuously as the winding

point shifts from tip to base of a ringframe bobbin and vice versa. Besides, the height of

the balloon also increases as the supply package becomes empty.

In the second zone, tensions are applied on the yarns by using tensioners so that yarns are

wound on the package with proper compactness. The objectionable yarn faults as well as

other contaminants (colored and foreign fibres) are also removed by using optical or

capacitance based yarn clearer.

In the third and final zone, yarns are wound on the package by means of rotational motion

of the package and traverse motion of the yarn guide. [9]

2.10.6 Machine parts [10]

Figure 2.17 Magazine type


2.10.7 Winding unit

Figure 2.18 Different parts of winding unit


2.11 Splicing

The process of piecing (joining) two yarn ends—resulting from yarn breaks, removal of a

yarn defect, or due to the end of the supply package—has received considerable attention

in the past two decades. An ideal yarn piecing would be one which can withstand the

subsequent processes without interruption and which does not lead to any deterioration in

the quality of the finished product. The yarn joining or piecing technique should be

suitable for all fibre types irrespective of yarn structure and linear density. Earlier

attempts in this area were directed to tying two ends by a weaver‘s knot or fisherman‘s

knot such that the ends do not slip apart. However, the size of the knot, which depends on

the type of knotter and the linear density of the yarns, would normally be two to three

times the diameter of the single yarn, leading to a characteristic objectionable fault in the

finished product. Knots have a detrimental effect on quality; they are obstructive because

of their prominence and so frequently cause breaks due to catching in thread guides or

even being sheared off. This leads to time-wasting stoppages of the machinery during

warping, sizing, and weaving. Due to the above-mentioned drawbacks of knotted yarns,

knotless yarn joining methods have received considerable attention by researchers.

2.11.1 Methods for producing knot-free yarns

The development of methods for producing knotless yarns began during the early 1970s.

Various methods have been used for producing knot-free yarn piecing, including.

Wrapping

Gluing

Welding or fusing

Splicing

a. Mechanical splicing

b. Electrostatic splicing

c. Pneumatic splicing


Figure 2.19 Different methods for producing knot-free yarn.

2.11.2 Pneumatic splicing

In this method, the yarn ends are inserted into a splicing chamber and then overlapped to

join them together by means of a strong current of compressed air. The splicing time and

air pressure are determined according to fibre type and yarn characteristics. The splicing

operation consists of the vertical application of air to the fibres and a simultaneous

rotational movement of the air to twist/untwist the yarn. This type of air movement is

achieved by the position of the blower apertures and the design of the shape of the

splicing chamber. Pneumatically spliced yarn produces a joint that can meet all the

requirements in subsequent processing, both in terms of strength and appearance. The

time taken to carry out efficient pneumatic splicing is relatively short, thus winding

efficiency is not severely limited. Moreover, pneumatic splicing can be applied to a wide

range of fibre and yarn types without requiring precise adjustments or settings, thus

facilitating efficient winding. [11]


2.11.3 Limitations of Pneumatic splicing

Pneumatic splicers use compressed air as media and driving force to carry out the splicing

procedure. As a result, lots of pipes or ductings are needed to ensure compressed air can

be constantly provided to the splicers. Due to the simple mechanism of the pneumatic

splicing, the untwisting power of the splicers is usually insufficient to wholly untwist the

broken yarn ends before re-twisting the two broken ends into a spliced yarn. The

drawback of insufficient untwisting power normally degrades the appearance, tensile,

bending and abrasion of the spliced yarns. [12]

Figure 2.20 Pneumatic splicing


2.11.4 Splicing operation

1. Yarn take-in

Push the upper and lower yarn into the splicer using the yarn guide levers, and then

clamp then there.

2. Cutting of the yarn ends

The upper and lower yarn cutters cut the ends of the upper and lower yarn.

Figure 2.21 Splicing operation (Yarn take-in and cutting of the yarn ends)

3. Untwisting

The cut yarn ends are sucked into the untwisting pipe and untwisted.

Figure 2.22 Splicing operation (Untwisting)


4. Splicing

The yarn guide lever is pushed in until it comes in contact with the splice length control

lever (Ln), pulling the yarn end out of the untwisting pipe by the appropriate length.

While the yarn ends are out they are held by the yarn holding lever, and a jet of

compressed air from the splicing nozzle tangles and twists the yarn ends together to

complete the splicing.

Figure 2.23 Splicing operation (Splicing)

2.12 Effect of variables on the properties of the spliced yarn

2.12.1 Effect of fibre properties and blend

Fibre properties such as torsional rigidity, breaking twist angle and coefficient of friction

affect splice strength and appearance.

2.12.2 Effect of yarn fineness

Coarser yarns have higher breaking strength but a moderate extension. The coarse yarn

cross section contains more fibres and provides better fibre intermingling during pre-

opening; hence the splice is stronger than that of finer yarns.

2.12.3 Effect of yarn twist

An increase in the twist significantly increases the breaking load and elongation, even at

higher pneumatic pressure. This could be due to better opening of the strands at higher


pneumatic pressure. Splicing of twisted ply yarn is more complicated than single yarn due

to the yarn structure having opposing twists in the single and doubled yarns. Twisted

yarns also require a relatively longer time for complete opening of the yarn ends.

2.12.4 Effect of different spinning methods

Yarn produced with different spinning methods exhibit different structure and properties.

Therefore, these yarns show significant differences in splice quality. The ring spun yarn

lent best splicing but the potential of splicing is affected by the spinning conditions. The

breaking strength percentage of ring spliced yarns to a parent yarn is 70% to 85% for

cotton yarn. However, the breaking strength and extension of splice vary with fibre and

yarn properties. Rotor spun yarns, due to the presence of wrapper fibres, make it difficult

to untwist and the disordered structure is less ideal for splicing. The breaking strength

retention varies from 54% to 71% and is much lower compared to the splice of ring spun

yarns. In case of friction spun yarns, the highest relative tensile strength obtained at the

spliced joints can be above 80%, but a number of splicing failures occurs due to

unfavorable yarn structure.

The air-jet-spun yarn and the cover spun yarn are virtually impossible to splice. Only very

low tensile strengths and elongation values can be attained due to the inadequate opening

of the yarn ends during preparation of the splicing. The coefficient of variation of these

properties is also generally high.

2.12.5 Effect of opening pressure

A study on 50/50 polyester cotton, 25 tex ring spun yarn shows a rise in tensile strength

up to a certain opening pressure. However, long opening time deteriorates the strength.

An increase in pressure up to 5 bar caused release of fibre tufts and fibre loss from the

yarn ends in P/C blend which is due to intensive opening, but beyond this pressure,

drafting and twisting in the opposite direction may also occur.

2.12.6 Effect of splicing duration

With a given splicing length, when the splicing is extended for a long period of time, the

breaking strength of the spliced yarn and also their strength retention over the normal

value of the basic yarn increases because of increased cohesive force resulting from an

increased number of wrapping coils in a given length. The effects are more pronounced at

higher splicing lengths. It is desirable however, that splicing duration be as short as

possible. The splicing duration alone has no conclusive effect on elongation properties of


splice yarn. It has also been observed that, for maximum splice strength, different

materials require different durations of blast. These are between 0.5 to 1.8 seconds.

2.12.7 Effect of splicing length

Studies on splicing of flyer and wrap spun yarns spun with different materials, showed

that regardless of the splicing material, the breaking strength and strength retention of

both yarn types increase with the splicing length because of the increased binding length

of the two yarn ends. Elongation at break and retention of elongation of both flyer and

wrap spun spliced yarns increase with the splice length. Compared to the splicing

duration, the splicing length has more pronounced effect on the load-elongation

properties of the spliced yarn. It can be therefore be stated that the splices made on longer

lengths and for longer period of time have more uniform strength.

2.12.8 Effect of splicing chamber

The factors like method and mode of air supply and pressure along with type of prism

affect the splicing quality. It was observed that irregular air pressure has advantages over

constant pressure for better intermingling in the splicing chamber, which varies with

different staple fibres, filament yarns, and yarns with S and Z twists. It is not possible to

make a general comment regarding potential of the splicing chamber due to the

multiplicity of factors influencing splicing. [13]

2.13 Assessment of yarn splice quality

During the assessment of quality of the obtained spliced joints, it is necessary to focus

special attention on two basic parameters: the strength of the joint and its similarity to the

yarn subjected to the splicing operation. [14]

2.14 Test parameters of splice

For all above mentioned reasons and to uphold the quality standards, it is very important

to maintain the correct timings, settings and tensions during the splicing process. In order

to measure quality level of the splice, the splice efficiencies (splice strengths) should be

tested.

Breaking force

The strength of a yarn is the resistance to deformation caused by application of a force.

The unit for the breaking force of the yarn is cN.


Breaking elongation

The breaking elongation of a yarn is the difference between the length of a stretched yarn

and its initial length, expressed as a percentage of the initial length. In case of tensile

testers it is usually measured until the maximum force is reached. The figure for the

breaking elongation of the yarn is calculated in percentage of nominal specimen length.

[15]

Retained splice strength (RSS %)

The ratio of breaking strength of spliced yarn and parent yarn is known as Retained

spliced strength. [16] % = × 100%

2.15 Quality parameters discussion

U % and CVm %

U % (unevenness) and CV % (co-efficient of variation) expresses the irregularity of

sliver, roving and yarn. Evenness of yarn means the degree of uniformity in respect of

mass per unit length, diameter, twist, color, hairiness, strength etc. However, popular

approach is to consider the variation in mass per unit length or thickness. Evenness of

laps, slivers and roving are also considered as the variation in the mass per unit length of

fibre strands. Variation in mass/unit length is generally due to variation in number of

fibres in the cross-section of the fibre strand.

Formula of co- efficient of variation

CV = × 100% [Where, σ = standard deviation, X = arithmetic mean]

IPI (Imperfection Index)

IPI stands for Imperfection Index of yarns, which is a measure of the sum of +50% thick

places, -50% thin places and +200% neps per 1000 m of tested yarn. This is for ring spun

yarns, while for rotor spun yarns the number of +280% neps per 1000 meters of the tested

yarns is considered instead of +200% neps. [17]


Thin places

If a place in the yarn exceeds -30% with respect to mean yarn cross-section and length is

8-12 mm it is called a thin place. Evenness testers like USTER TESTER-4 & USTER

TESTER-5 allow the 4 sensitivity thresholds (limits) for thin places: -30%, -40%, -50%, -

60%. Every time the selected limit is exceeded, a thin place is counted.

Thick places

If a place in the yarn exceeds +35% with respect to mean yarn cross-section and length is

8-12 mm it is called a thick place. Evenness testers like USTER TESTER-4 & USTER

TESTER-5 allow the 4 sensitivity thresholds (limits) for thick places: +35%, +50%,

+70%, +100%. Every time the selected limit is exceeded, a thick place is counted.

Neps

A nep is a very short thick place in the yarn or entangled mass of fibres. It can be fibre

nep, seed coat nep or a trash particle. The maximum length for a nep is limited to 4mm.

Evenness testers like USTER TESTER-4 & USTER TESTER-5 allow the 4 sensitivity

thresholds (limits) for neps: +140%, 200%, +280%, +400%. Every time the selected limit

is exceeded, a neps is counted.

Nep is calculated to a reference length of 1mm. A 100% increase over 3 mm would

correspond to a 300% increase over 1 mm and would be counted as a nep at a set limit of

200%.

Neps +140% means that the cross-section at the nep is 240% of the mean yarn cross-

section.

The less imperfections in the yarn, the better the appearance of the fabric

Imperfections Ring-spun-yarn

Thin places - 50%

Thick places + 50%

Neps + 200%

CSP (Count Strength Product)

CSP is an old Strength value, which is not used in several countries anymore.

It is a number which is derived by multiplication of yarn count (Ne) and lea strength (in

lbs.).


Higher the values, better the yarn.

CSP = Yarn count (Ne) × lea strength (in lbs.)

Lea: In one lea 120 yards length of yarn is wound by 80 wraps. Each wrap has a length of

1.5 yards.

Lea strength: This is breaking load required to break one lea. It is generally

expressed in pound. Higher the value, stronger the yarn. [18]


Chapter 3

Materials and Methods


3.1 Fibre used

The property of the raw cotton determines the processing parameters of the spinning

machinery and the quality of final yarn. However for the current experiment, 100% Mali

cotton was used.

Lay down

33 bales were laid down at automatic bale opener.

Table 3.1 Fibre properties

Properties Value

Micronaire (µg/inch) 4.39

Strength (g/tex) 33.3

Length (mm) 28.65

Uniformity Index (%) 84.1

SCI 139

Nep (Cnt/g) 239

SCN (Cnt/g) 28

SFC (n) 20.5

IFC (%) 4.4


3.2 Sample preparation

Flow chart of the experimental process

Figure 3.1 Flow chart of the experimental process


3.3 Machinery used

Figure 3.2 Winding machine

Machine name: Winding Machine

Manufacturer : Muratec, Japan

Model: 21C

Function: To produce cones


Figure 3.3 Uster Quantum 2

Machine name: Uster Quantum 2

Manufacturer : Zellweger Uster, Switzerland

Model: SE 617

Function: To detect distrubing yarn faults and remove them


3.4 Description of Quality Control Equipments

Figure 3.4 Uster HVI Spectrum

Name: USTER HVI Spectrum


Function: To test and give results on important fibre properties.


Figure 3.5 Uster AFIS Pro

Name: USTER AFIS Pro (Advanced Fibre Information System)


Function: To test the number and size of neps, different fibre lengths, fibre maturity etc.


Figure 3.6 Uster Tester-5

Name:Uster Tester-5


Function: To test evenness, imperfection and hairiness of yarns and other strands such as roving and slivers.


Figure 3.7 Uster Autsorter-5

Name:Uster Autosorter-5


Function: To weigh certain lengths and give English Counts (Ne) of slivers roving’s and yarns.


Figure 3.8 Electronic yarn reel

Name: Electronic Yarn Reel

Manufacturer: England

Function: It is used to wrap yarn into skeins.


Figure 3.9 Bundle strength tester

Name: Bundle strength tester

Manufacturer: Mesdan, Italy

Function:To measure bundle yarn strength


Figure 3.10 Tecloch

Name: Tecloch

Model: SLW

Manufacturer: Japan

Function: To measure strength of splice


3.5 Technical parameters and settings

Table 3.2 Blowroom specifications and settings

Machine name, specifications and settings

Blow Room Line

UNIflock

Model No. :A11

Plucking Depth :4 mm

Traverse Speed :16 m/min

Efficiency :88%

UNIclean

Model No. :B11

Cleaning Intensity :0.8

Relative Waste :8

Efficiency :99%

UNImix

Model No. : B70

Degree of opening : 0.5

Mixing chamber : 8

Efficiency : 73%

UNIflex

Model No. :B60

Cleaning Intensity :0.5

Relative Waste Rate :8

Efficiency :86%


Table 3.3 Carding specifications and settings

Carding

Manufacturer :Rieter

Model No. :C 60

Production :62 kg/hr

Sliver Weight :101grains/yd

Sliver length/Can :6290 m/can

Delivery speed :165 m/min

Efficiency :99%

Table 3.4 Breaker Drawframe specifications and settings

Breaker Drawframe

Manufacturer : Rieter

Model No. : SB D15

Delivery Speed : 700 m/min

Sliver Weight : 75 grains/yd

Sliver length/Can : 5000m

Doubling : 6

Gauge : 44mm x 48 mm

Draft : 6.83

Drafting zone : 4-over-3


Table 3.5 Finisher Drawframe specifications and settings

Finisher Drawframe

Manufacturer :Rieter

Model no. :RSB D35

Delivery speed :550 m/min

Sliver weight :75 grains/yd

Sliver length/Can :2690 m

Doubling :8

Gauge :44 mm × 48 mm

Draft :8.61


Table 3.6 Simplex specifications and settings

Simplex

Manufacturer :Toyota

Model No. :FL 100

Flyer speed :1160 rpm

Roving hank :0.8

TPI :3.13

Draft : 7.27



Table 3.7 Ring Frame specifications and settings

Ring Frame

Manufacturer : Toyota

Model No. : RX 240

Spindle Speed : 15,500 rpm

Roving Hank : 0.8 Ne

Yarn Count : 36 Ne

TPI : 21

Draft : 45


Traveler : 2/0

Spacer : Normal, 2.2mm (yellow)

Yarn weight : 48 gm per bobbin

Table 3.8 Winding machine specifications and settings

Winding machine

Manufacturer : Muratec

Model No. : 21C

Winding Speed : 1480 m/min

Yarn Count : 36 Ne

Yarn tension : 280 cN

Splicing length : 20 mm

Air pressure : 0.6 MPa

Untwisting time : 0.71 sec

Twisting time : 0.08 sec


Figure 3.11 Uster Quantum 2

Table 3.9 Uster Quantum 2 specifications and settings

Uster Quantum 2


Model No. : SE 617

IMK type : IMK-C15-F23

Table 3.10 Sample name of different clearer settings

Sample-1 Close setting

Sample-2 Moderate setting

Sample-3 Wide setting


Table 3.11 Close yarn clearer settings for sample-1

Thick place

% cm

N 200 0.0

S 120 1.2

L 20 20.0

H1 100 1.5

H2 90 2.5

H3 80 5.0

H4 60 15.0

H5 45 30.0

H6 0 0.0

Thin place

-% cm

T 30 12

H1 42 3

H2 38 5

H3 35 7

H4 28 20

H5 26 30

H6 0.0 0.0


Table 3.12 Moderate yarn clearer settings for sample-2

Thick place

% cm

N 250

S 180 1.5

L 40 20

H1 140 3

H2 100 4.2

H3 75 6.5

H4 35 32

H5 0.0 0.0

H6 0.0 0.0

Thin places

% cm

T 30 16.0

H1 42 3.0

H2 36 6.0

H3 33 11.0

H4 26 32.0

H5 0 0.0

H6 0 0.0


Table 3.13 Wide yarn clearer settings for sample-3

Thick place

% cm

N 500 0

S 300 10

L 90 90

H1 0 0.0

H2 0 0.0

H3 0 0.0

H4 0 0.0

H5 0 0.0

H6 0 0.0

Thin places

% cm

T 45 45

H1 70 10

H2 60 18

H3 40 28

H4 30 10

H5 0 0.0

H6 0 0.0


In this experiment, we kept foreign matter dark settings for all three samples same and

other channels of Uster Quantum 2 were kept disabled.

Table 3.14 Foreign matter dark settings

Foreign matter dark

% cm

FD 7 1.3

H1 16 0.1

H2 5 1.2

H3 0 0.0

H4 0 0.0

H5 0 0.0

H6 0 0.0


3.6 Working procedure

o Fibre Testing: First of all, fibre properties of the concerned lot were collected by

testing in USTER HVI SPECTRUM and Uster AFIS Pro.

o From blowroom to ringframe production of 36KH ring yarn was observed

carefully which was produced in regular factory process. Process parameter and

settings of each machine was noted down accordingly.

o From a individual ringframe, 300 ring cops were selected for experimental

procedure and they were separately collected after doffing.

o They were divided into 3 groups each containing 100 cops among these 3 groups

10 ring cops were selected randomly for testing of ring frame yarn properties by

using UT-5, bundle yarn strength tester, Uster auto sorter-5 and Electronic wrap

reel.

o 3 drums of winding machine were selected for experimental procedure, later they

were given separate settings individualized into a group.

o 3 different yarn clearer settings were chosen for Uster Quantum 2 and for each

setting data was observed from both winding machine and Uster quantum 2

monitor.

o Production of winding and wastage were calculated for each yarn clearer settings.

o Strength of splice joints were measured with Tecloch and compared with parent

yarn.

o Then yarn samples were taken to Quality Control Department. Actual counts

(Nominal count: 36 Ne) of the all samples were first checked. And then samples

were tested in UT-5 (for evenness, imperfections), bundle yarn strength tester,

Uster auto sorter-5, Electronic wrap reel.

o Count strength product (CSP) of the yarn samples was also measured.


Chapter 4

Results and Discussion


4.1 Test results in tabular form

The test results obtained from different testing equipments are given below

Table 4.1 Observed Uster Quantum 2 and Autoconer data

Sample No Yarn fault Spindle Winding Waste generation

cuts efficiency% production %

(SEF%) (Kg/shift)

Sample-1 219.1 60.20 383.61 3.12

Sample-2 64.6 80.00 511.48 0.92

Sample-3 53.4 83.30 530.66 0.76

Table 4.2 Test results of UT-5 and bundle strength tester

Observations CVm Thin Thick Nep IPI CSP (Ne×lb)

(%) place place (200%)

(-50%) (50%)

Ring yarn 14.17 4 148 281 432.6 2424

Sample-1 14.37 3.5 143 351 497.6 2277

Sample-2 13.93 1.3 122 310 432.9 2346

Sample-3 14.29 3.3 144 355 502.1 2368


Table 4.3 Data of determination of splice strength by Tecloch equipment

No of observation Spliced yarn strength (N) Parent yarn strength (N)

1 1.7 1.8

2 1.6 1.7

3 1.6 1.8

4 1.7 1.9

5 1.5 1.7

6 1.3 1.6

7 1.8 1.9

8 1.6 1.7

9 1.5 1.6

10 1.6 1.7

Mean 1.6 1.74

Breaking strength of spliced yarn

RSS% = Breaking strength of parent yarn

× 100% 1.6 = 1.74 × 100%

Retained splice strength, RSS% = 91.95%

*All the yarn samples were kept in quality control lab for 24 hours. Temperature was

recorded 27 °C and Relative humidity was recorded 62%.


4.2 Graphical Representation and Discussion

The data collected from different tests were analyzed and discussed with graphical

representation

4.2.1 Comparison of number of yarn fault cuts (N, S, L, T) of samples due to

different yarn clearer settings

250 219.1

200

150

Sample-1

100

Sample-2

64.6

Sample-3

53.4

50

0

Sample-1 Sample-2

Sample-3

number of yarn fault cuts

Figure 4.1 Comparison of number of yarn fault cuts of samples due to different yarn

clearer settings.

It was observed from the above figure that the number of yarn fault cuts for sample-1 was

more than other settings. This was due to close setting of yarn clearer, the clearing limit

passed through the yarn body which caused excessive number of cuts. In sample-2, due to

moderate setting of yarn clearer, it was observed that the number of yarn fault cuts were

considerably lower than the sample-1. In this yarn clearer setting, the clearing limit did

not pass through the yarn body. The clearing limit was between the yarn body and seldom

occurring faults which caused only prominent yarn faults in the yarn to be detected and

removed. Hence the numbers of cuts were significantly lower though it removed


objectionable yarn faults. In sample-3, due to wide setting of yarn clearer the clearing

limit was away from the yarn body and it even allowed many prominently occurring yarn

faults to pass. Since many faults were allowed to be passed without being cut, this has the

lowest number of cuts.

4.2.2 Comparison of mass variation (CVm%) of ring yarn and cone yarn of different

yarn clearer settings

14.4 14.37

14.3

14.2

14.29

14.17

14.1

14 13.93

13.9

13.8

13.7 Di…

Ring yarn Sample-1 Sample-2 Sample-3

Ring yarn

Sample-1

Sample-2

Sample-3

Figure 4.2 Comparison of mass variation (CVm%) of ring yarn and cone yarn of

different yarn clearer settings.

It was observed from above figure that the co-efficient of variation (CVm%) was higher

for sample-1 than Ring yarn. The reason behind this was due to close setting of yarn

clearer the threshold for yarn faults were quite strict which caused larger number of yarn

cuts. After each yarn cuts, the yarn ends of cone and cop were joined by splicing. Though

many yarn faults were removed in close settings of yarn clearer in sample-1, high co-


efficient of variation was due to inability of spliced yarn to have evenness same as that of

parent yarn. In sample-2, coefficient of variation CVm% was lower than that of ring yarn

due to moderate settings of yarn clearer. Mostly prominent yarn faults were removed

keeping the number of yarn cuts much lower than sample-1. Since in sample-2,

irregularity introduced by splicing was lower and prominent yarn faults were removed the

co-efficient of variation was lower. In sample-3, co-efficient of variation CVm% was

slightly higher than that of ring yarn. This was because in sample-3, due to wide setting of

yarn clearer the ring yarn was allowed to pass with yarn faults. Slight increase in co-

efficient of variation could be attributed to splices due to foreign cuts, breakage in yarn

due to tension, change of cops.

4.2.3 Comparison of thick place (+50%) of ring yarn and cone yarn of different yarn

clearer settings

160

148

144

143

140 122

120

100 Ring yarn

80 Sample-1

60 Sample- 2

Sample- 3

40

20

0

thick place (+50%)

Figure 4.3 Comparison of thick place (+50%) of ring yarn and cone yarn of different

yarn clearer settings.

It was observed from above figure that the amount of thick place in sample-1 was slightly

less than ring yarn. This was due to in close setting larger number of yarn fault cuts were

observed. Each of these cuts was replaced by splice. Though splice replaces the yarn

fault, the splice itself was not perfect. The spliced region could be detected as thick fault

though its magnitude was lower. As a result, though many thick places were removed

there was no significant change in number of thick places when compared with ring yarn.

In sample-2, amount of thick place was much lower than that of ring yarn due to removal


of prominent yarn faults which includes thick places but the number of splicing due to

yarn cuts is lower which results in formation of lower number of thick places. In sample-

3, the setting for yarn clearer was wide which allowed most of the thick place in ring yarn

to pass freely without being cut causing the number of thick place being almost similar

with that of ring yarn.

4.2.4 Comparison of thin place (-50%) of ring yarn and cone yarn of different yarn

clearer settings.

4 3.5

3.3

4

Ring yarn

3.5

Sample-1

3

1.3

Sample-2

2.5

Sample-3

2

1.5

1

0.5

0

thin place(-50%)

Figure 4.4 Comparison of thin place (-50%) of ring yarn and cone yarn of different

yarn clearer settings

It was observed that number of thin place was high at sample-1. This was because in

sample-1 due to close setting of yarn clearer highest number of yarn fault cuts and

splicing were observed. In sample-2, amount of thin place was slightly less that of ring

yarn but lowest among other samples. Since the number yarn fault cuts were kept at

optimum while removing prominent yarn faults. In sample-3, amount of thin place was

high due wide clearing limit which allowed faults already present in ring yarn to pass

without being removed and winding added further imperfections.


4.2.5 Comparison of neps of ring yarn and cone yarn of different yarn clearer

settings

400

350

300

250 281

310 355

Ring yarn

351 Sample-1

200 Sample-2

150

Sample-3

100

50

0

amount of neps

Figure 4.5 Comparison of neps of ring yarn and cone yarn of different yarn clearer

settings.

It was observed from figure above that, after winding the number of nep increases. This

increase in neps was caused by accumulation of loose fibres on various parts of winding

machine which were later incorporated onto yarn during winding. Furthermore, abrasion

of yarn with various contact points in yarn path created neps and sometimes spliced

region may have a nep at centre or two at splice tails. It was observed that amount of nep

was high in sample-1. This was because in sample-1 due to close setting of yarn clearer

larger number of yarn nep cuts and splicing were observed. In sample-2, amount of nep

was slightly more that of ring yarn but lower than other samples, since the number of yarn

fault cuts were kept at optimum while removing prominent neps. In sample-3, amount of

nep was highest due to wide clearing limit which allowed yarn neps to be passed without

being removed.


4.2.6 Comparison of IPI of ring yarn and cone yarn of different yarn clearer settings

502 498

520

500

480 Ring yarn

460 433 432

Sample-1

Sample-2

440 Sample-3

420

400

380

amount of IPI

Figure 4.6 Comparison of IPI of ring yarn and cone yarn of different yarn

clearer settings.

It was observed from the figure above that winding has adverse effect on IPI. These

increases in IPI values were caused by accumulation of loose fibres on various winding

parts which were later passed onto yarn during winding. Furthermore, abrasion of yarn

with various contact points in yarn path created imperfections and sometimes spliced

region may replace a prominent yarn fault with several less disturbing faults. It was

observed that IPI value was highest at sample-1. This was because in sample-1 due to

close setting of yarn clearer highest number of yarn fault cuts and splicing were observed.

In sample-2, IPI value was almost similar to ring yarn. Since the number yarn fault cuts

were kept at optimum while removing prominent yarn faults. In sample-3, IPI value was

high due wide clearing limit which allowed faults already present in ring yarn to pass

without being removed and winding added further imperfections.


4.2.7 Comparison of CSP of ring yarn and cone yarn of different yarn clearer

settings

2450 2424

2400 2346 2368

2350

Ring yarn

2277

Sample-1

Sample-2

2300

Sample-3

2250

2200

CSP(Ne×lb)

Figure 4.7 Comparison of CSP of ring yarn and cone yarn of different yarn clearer

settings.

It was observed from figure above that CSP of sample-1, sample-2 and sample-3 was

lower than ring yarn. This phenomenon was caused due to yarn cuts by yarn clearer. After

each yarn cut, the yarn ends of cone and cop were joined by splicing. It was observed in

Table 4.3 that, spliced yarn strength is lower than parent yarn strength. So, high number

of splices resulted in more weak places in yarn body and therefore caused reduction of

yarn strength.

Sample-1 had lowest CSP value among the samples since due to close settings of yarn

clearer the threshold for yarn faults were quite strict which caused larger number of yarn

cuts which were rejoined by splice. Sample-2 had lower number of yarn cut due to

moderate yarn clearer settings thus less number of splice and had higher CSP value than

sample-1. Sample-3 had lowest number of yarn cuts due to wide yarn clearer settings thus

lowest splice and highest CSP value among samples.


4.2.8 Comparison of SEF% of cone yarn of different yarn clearer settings

100.0%

90.0% 80% 83%

80.0%

60%

70.0%

60.0%

Sample-1

50.0%

Sample-2

40.0%

Sample-3

30.0%

20.0%

10.0%

0.0%

spindle efficiency %

Figure 4.8 Comparison of SEF% of cone yarn of different yarn clearer settings.

It was observed from figure above that spindle efficiency %(SEF%) for sample-1 was

very low due to larger number of yarn faults were cut. After each cut winding process

stopped and yarn cuts were rejoined by splicing. It had a significant impact on spindle

efficiency. In sample-2, number of yarn cuts was lower than sample-1 due to moderate

settings of yarn clearer thus increasing the spindle efficiency % (SEF%) than sample-1. In

sample-3, number of yarn cuts was lowest due to wide settings of yarn clearer thus giving

highest spindle efficiency% (SEF%).


4.2.9 Comparison of productivity of cone yarn of different yarn clearer settings.

600

530.66

Sample-1

511.48

Sample-2 500

Sample-3

383.61

400

300

200

100

0

production (kg/shift)

Figure 4.9 Comparison of productivity of cone yarn of different yarn

clearer settings.

Productivity of winding operation was directly affected by winding speed and number of

cuts. Winding speed for all samples was kept equal so the key factor in this experiment

was number of cuts. Yarn clearer settings with closer clearing limit had higher number of

cuts than yarn clearer settings with wide clearing limit. The number of cuts directly

affected the spindle efficiency. Figure shown above indicates that for sample-1,

productivity is much lower due to low spindle efficiency% (SEF%). In sample-2,

productivity was much higher than sample-1 due to higher spindle efficiency% (SEF%)

than sample-1. In sample-3, productivity was much higher than all other samples due to

highest spindle efficiency% (SEF%).


4.2.10 Comparison of wastage% of winding machine due to different yarn clearer

settings

3.5%

3.12%

3.0%

2.5%

2.0% Sample-1

1.5% 0.92%

Sample-2

0.76%

Sample-3

1.0%

0.5%

0.0%

wastage %

Figure 4.10 Comparison of wastage% of winding machine due to different yarn

clearer settings

Wastage generation of winding machine was affected by the number of yarn cuts since

during piecing of yarn, some portion for yarn from cone and cop were unwound and

wasted. During this process excess yarn portions were cut. Thus higher number of yarn

cuts produced more hard waste. In sample-1, number of yarn cuts was highest thus

generating most waste than other samples. In sample-2, number of yarn cuts was lower

than sample-1 having lower waste generation. In sample-3, waste generation was lowest

due to lowest number of yarn cuts.


4.2.11 Comparison between spliced yarn strength and parent yarn strength

1.8

1.74

1.75

1.7

1.65

Spliced yarn strength (N)

1.6

Parent yarn strength (N)

1.6

1.55

1.5

Figure 4.11 Comparison between spliced yarn strength and parent yarn strength

In comparison between spliced yarn strength and parent yarn it was observed that, spliced

yarn did not achieve same strength as parent yarn. During splicing weak space was form

at the joint which did not have same strength as parent yarn.


Chapter 5

Conclusion


5.1 Key findings

It was observed that sample-1 has the highest number of yarn fault cuts than

sample-2 and sample-3 where sample-3 showed lowest number of yarn fault cuts.

On the other hand number of yarn fault cuts for sample-2 was found in between

sample-1 and sample-3.

Both sample-1 and sample-3 showed higher CVm% than ring yarn where sample-

1 was the highest. On the other hand sample-2 had lower CVm% than that from

sample-1, sample-3 and ring yarn.

It was observed that both sample-1 and sample-3 had higher IPI value than ring

yarn where sample-2 showed no significant change of IPI value than that from

ring yarn.

CSP values for all samples was observed lower than that from ring yarn where

sample-1 was lowest, sample-2 had higher value than sample-1 but sample-3 had

highest CSP value among all these samples.

Spindle efficiency% for sample-3 was observed highest and for sample-1 it was

lowest where spindle efficiency% for sample-2 was in between sample-1 and

sample-3.

In case of production, it was observed that sample-3 had the highest productivity

and for sample-1 it was lowest. Alternatively productivity for sample-2 was found

in between sample-1 and sample-3.

In case of waste generation it was observed that sample-1 had the highest waste

generation% and for sample-3 it was lowest where waste generation% for sample-

2 was in between sample-1 and sample-3.

5.2 Limitations

The hairiness module of Uster Tester-5 was disabled. Therefore, we could not

observe hairiness properties of yarn before and after winding.

There was no single yarn strength tester as a result we could not observe tenacity,

breaking elongation of yarn before and after winding.

The method used for calculating waste% was not accurate enough since it was not

possible to collect waste data individually from three drums. Thus waste% data

was calculated based on data of winding waste produced per shift due to cuts.


Only three yarn clearer settings were used in this project due to unwillingness of

factory authority to spare more time, material and machine. So, it was not possible

to observe intermediate yarn clearer settings which would have helped to

understand more effectively about the consequence of clearing limits on different

yarn properties and productivity.

5.3 Conclusion

Based on experiments and observations conducted in this project work, it can be

concluded that clearing limit of yarn clearer has a significant impact on yarn quality and

productivity of winding machine. Yarn clearer setting, too close or too wide, had adverse

effect on yarn quality. When the yarn clearer setting was too close, the clearing limit did

cut across the yarn body causing excessive cuts than normal. Again when clearing limit

was too wide, it allowed faults in ring yarn to pass freely to cone. The number of cuts

during winding operation was directly affected by sensitivity of yarn clearer. Higher

number of cuts caused drop in spindle efficiency and productivity with increase in waste

generation. So to achieve better yarn quality and productivity the number of cuts were to

be kept at optimum while removing disturbing yarn faults. Therefore, it can be concluded

that the appropriate clearer setting is crucial for optimum yarn quality and productivity

level and is needed to be determined by trial and error method.


References

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Annexure
