INDUSTRIAL TRAINING REPORT

LEKAMGE M.S

EN12ME3036

DEPARTMENT OF MECHATRONICS ENGINEERING

FACULTY OF ENGINEERING

SOUTH ASIAN INSTITUTE OF TECHNOLOGY AND MEDICINE

SRI LANKA

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INDUSTRIAL TRAINIG REPORT

TRAINEE

NAME : LEKAMGE M.S

STUDENT ID : EN12ME3036

TRAINING ORGANIZATION

NAME : MAS Holdings

BRANCH/DFEPARTMENT : Trischel Fabric Pvt Ltd

SUPERVISING OFFICER : Mr. Ruwan Nilwakka

PERIOD OF TRAINING : FROM 03.06.2013 TO 03.09.2012

TRAINING DURATION : 12 WEEKS

FIELD OF TRAINING : MECHATRONICS ENGINEERING

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ACKNOWLEDGEMENTS

I undergo my internship that begins on early June this year till end of August. I

finally successfully completed my Industrial training. I have learnt a lot of valuable

things while working here. I realize that learning theoretical is never the same when it

comes to practice. During these 3 months working here I am exposed to many new

things which are very valuable for me to learn and carry out with devotion when I face

the real world of working in the future.

I would like to take opportunity to express my humble gratitude to Mr. Ruwan

Nilwakka (Engineering manager, Trischel Fabric) and Mr. Ajith Subasinghe (Human

resources manager, Trischel Fabric) for their advices and patiently guiding me through

while I working here as a trainee. it would not have been possible without the kind

support and help of many individuals and organizations. I also would like to extend my

thankfulness to my father and mother for all their moral support, financial support

during my training here. Not forgotten for all the staffs working at MAS holdings. I very

much appreciate for their entire kindness helping and teaching me when I’m working

there. I am highly indebted to MAS holdings for their guidance and constant supervision

as well as for providing necessary information regarding the training period.

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ABSTRACT

The abstract should briefly introduce the training organization highlighting the

engineering aspects, and provide a summary of the report.

MAS Fabric Park is Sri Lankan's first privately owned fabric intensive free trade

zone. It is the leader in industrial multi facility connectivity empowering the Apparel

and Fabric manufacturing industry the best supply chain solution in a sustainable

industrial eco system. Equipped with an array of shared services it offers a complete

solution to investors for a seamless plug n play operation.

Engineering Department

1. Services(utility)

i. Electricity (MFP)

ii. Steam (MFP)

iii. Water (MFP)

Softener (Trischel)

iv. Compressed air (Trischel)

v. Central air condition (Trischel)

Chillers

Ventilation system

vi. Thermic fluid heating (Trischel)

vii. Effluent treatment (MFP)

2. Breakdown maintains

3. Prevent maintains

4. Fabrication

5. Civil works

Those are the tasks under the engineering department.

MFP- MAS Fabric Park

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CONTENTS

Page

1. Introduction ............................................................................................................. xx

2. Training Experience ................................................................................................ xx

3. Water softening system ........................................................................................... xx

4. Compressed air system ............................................................................................ xx

5. Variable frequency drive ......................................................................................... xx

6. A/C system .............................................................................................................. xx

7. Warping section ...................................................................................................... xx

8. Knitting section ....................................................................................................... xx

9. Dying section .......................................................................................................... xx

10. Finishing section ..................................................................................................... xx

11. Programmable logic controller ................................................................................ xx

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CHAPTER 1

INTRODUCTION

1.1 Overview of Trischel Fabric Pvt Ltd

I was assigned to Trischel Fabric Pvt Ltd as an implant trainee for a period of 12

weeks starting from 3rd of June 7, 2013.

MAS warp knit facility set up in 2008 originally as a joint venture is now a fully

owned unit of the organization. This facility is the first of its kind in South Asia, and

manufactures warp knit fabric for swimwear and intimate apparel.

MAS Holdings, in its strategic technological partnership with Elastic Textile

Europe GmbH, offers Trischel the competence to expand on its range of products to its

customers through this collaboration in Sri Lanka. The facility won the Akimoto 5S

Award for Best Plant in the Manufacturing sector in the year.

Trischel also produces high quality warp knit fabric which is prepared for print

(PFP) through our printing arm Textprint.

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CHAPTER 2

TRAINING EXPERIENCE

For the past 3 months in Trischel Fabrics, I’ve been in few Departments which

are Warping, Knitting, Finishing, Engineering Store and Quality testing Department. I

got the opportunity to learn about processes of those departments.

During my training period I am successfully completed the following areas

related to Engineering process and production process or their company.

1. Warping, Knitting, Finishing, Colour Lab, Quality Assurance Lab Process

2. Water softener system

3. Thermic oil system

4. HVAC (Heating Ventilation & Air Condition) system

5. PLC (Programmable Logic Controller)

6. Water treatment Plant Process

7. Effluent Plant (Waste water Treatment Plant)

8. Biomass Steam Boiler

9. Electrical Steam Boiler

Actually I identified services which are done by the engineering department. As

the requirement of the production they have to supply processed water, compressed air,

chilled water, thermic oil, steam, etc. Engineering department has the responsibility to

supply all those requirements as they need. Most important thing is once if they fail to

supply one of those requirements that will cause to a breakdown of the production.

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CHAPTER 3

WATER SOFTENING SYSTEM

Water softening is the removal of calcium, magnesium, and certain other metal

cations in hard water. In here they use softener water to dying process of the fabric. So

that they have a system called water softener.

Hardness of the water which use for dying process should be lower than 10ppm

as the requirement. But normally the hardness of water coming from MFP (MAS Fabric

Park) is around 60ppm. That water softener system can reduce the hardness of water to

0.3ppm from 60ppm. That may be increase up to 10ppm while pumping process from

sump to dying machines. That might not be a big issue for the process.

The process of softening is done by iron-exchange resins(R-Na) which they have

added into the softener tanks. Those ion-exchange resins are used to replace

the magnesium and calcium ions found in hard water with sodium ions. We can write the

equation as below,

𝑅 − 𝑁𝑎 𝑤𝑎𝑡𝑒𝑟→ 𝑅 − 𝐶𝑎 + 𝑁𝑎𝐶𝑂3 + 𝐻2𝑂

When the resin is fresh, it contains sodium ions at its active sites. When in

contact with water containing magnesium and calcium ions, the magnesium and calcium

ions preferentially migrate out of solution to the active sites on the resin, being replaced

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in solution by sodium ions. . Then softener water goes to the cool water sump where in

underground. Likewise there are two softer tanks and two salt tanks to back wash

process of two softener tanks.

Back wash & Regeneration

During the softening process, the ion-exchange resins gets inactive. So it has to

be cleaned and regenerated. So in a period of time its controlling system automatically

does a back wash and regeneration.

Water contains mud and other wastes. When water goes thorough ion-exchange

resins these wastes sticks on resins. This causes the ion-exchange resins to get inactive.

So to clean those waste which are stick on the resins a back washing is done by pumping

the softened water back in to the softening tank from the bottom and drain it from the

top of the tank.

During the softening process Na ions in the ion-exchange resins get decreased,

so they have to be regenerated. As mentioned above after doing the back wash another

process called regeneration is done to re generate the ion-exchange resins. This is done

by pumping salt water (NaCl + H2O) in to the softening tank. We can write the equation

as bellow,

𝑅 − 𝐶𝑎𝑠𝑎𝑙𝑡 𝑤𝑎𝑡𝑒𝑟→ 𝑅 − 𝑁𝑎 + 𝐶𝑎𝐶𝑙 + 𝐻2𝑂

Most important part of that is distribution of that softener water throughout the

factory. So that they use pump and motor system with a control panel for it. The basic

thing to keep constant is pressure of the output pipe line. Usually in here keep 5 bar of

pressure in output pipe.

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Control panel

Basically that control panel controls those three motors which are connected to

three pumps. That works according to the pressure of the output pipe line. The control

panel gets this pressure feedback from a pressure sensor. Then it decides how many

motors should run to supply that pressure and it can vary the speed of a one motor too.

That is doing by a VSD controller.

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CHAPTER 4

COMPRESSED AIR SYSTEM

In Trischel factory they use compressed air for pneumatic operations and as well

as other works like cleaning, fire, stenter machine, dying process etc. So they have a

compressed air system including basically two air compressors and two dryers and a

7bar receiver tank. But they only use one compressor at the same time.

There are few types of air compressors.

Reciprocating Air Compressors

Rotary Screw Compressors

Centrifugal Compressors

In here they use screw air compressors.

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Screw air compressor

Normally rotary screw type air compressors use where large volumes of high

pressure air needed. Rotary screw air compressors are easy to maintain and operate. The

gas compression process of a rotary screw is a continuous sweeping motion, so there is

very little pulsation or surging of flow, as occurs with piston compressors.

Process inside of the compressor

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Firstly the fresh air gets into the compressor through an air purifier. That air capacity is

controlled by a valve before the compression engine. Once that air going through the

compression engine it directly go to the oil tank. After that compressed air goes to oil

cooler through the oil separator. Oil separator has the ability to separate compressed air

from the oil which mix with the oil when the compression process. Then the

compression process of the air is almost done. But that compressed air may have little

moisture with it. So that finally it goes through the dryer which can remove moisture

from the air.

Compression engine

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There are two meshing helical screws inside of the compression engine. These are

called as rotors. In a dry running rotary screw compressor, timing gears ensure that the male

and female rotors maintain precise alignment. In an oil-flooded rotary screw compressor,

lubricating oil bridges the space between the rotors, both providing a hydraulic seal and

transferring mechanical energy between the driving and driven rotor. Gas enters at the suction

side and moves through the threads as the screws rotate. The meshing rotors force the gas

through the compressor, and the gas exits at the end of the screws.

Air compression theory

Even though air is not a perfect gas, the presence of nitrogen and oxygen in major

proportion makes it obey very closely to a perfect or ideal gas. We all know that an Idea” gas

obeys some laws. They are

1. Boyle’s law (PV=C).

2. Charles’s law (V/T = C).

The above two laws can be combined to form a combination law which can be

represented as

𝑃𝑉

𝑇= 𝐶

Keeping the combination law in mind, when the air is compressed, the pressure and

temperature of the air increases as the volume of the space containing air reduces.

This can be understood better when used in Boyle’s law and Charles’s law separately.

Boyle’s Law:

PV=C. or P is inversely proportional to V. As the volume of the space containing air

reduces, the pressure increases.

Also when volume V, is kept constant, the pressure P, is directly proportional to the

temperature T. Thus as the pressure of the air is increased due to compressing, the temperature

also increases. Thus as a result of compressing air, the pressure and temperature increases as the

volume decreases.

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CHAPTER 5

VARIABLE FREQUENCY DRIVE

Variable frequency driver (VFD) can control speed of an electric motor by

varying the frequency and voltage supplied to the motor. That variable frequency driver

has a very important place in the industry when we considering the power consumption

of a system. That VFD is also called as adjustable speed drive, adjustable frequency

drive, AC drive, micro drive, and inverter.

As we know frequency is the only variable directly affect to the speed of an AC

induction motor. That frequency of an AC current is directly proportional to the speed of

the motor. In industry always does not require an induction motor to run full speed the

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VFD can be used to rpm down the frequency and voltage to meet the requirements of

the electric motor’s load. As the application’s motor speed requirements change,

the VFD can simply turn up or down the motor speed to meet the speed requirement.

The first thing of a Variable Frequency Drive is the Converter. The converter is

equipped with diodes. They allow current to flow in only one direction; the direction

shown by the arrow in the diode symbol. For example, whenever a phase voltage is

more positive than B or C phase voltages, then that diode will open and allow current to

flow. When B-phase becomes more positive than A-phase, then the B-phase diode will

open and the A-phase diode will close. The same is true for the 3 diodes on the negative

side of the bus. Thus, we get six current “pulses” as each diode opens and closes. This is

called a “six-pulse VFD”, which is the standard configuration for current Variable

Frequency Drives.

We can get rid of the AC ripple on the DC bus by adding a capacitor. This capacitor

absorbs the ac ripple and delivers a smooth dc voltage. The actual voltage will depend

on the voltage level of the AC line feeding the drive, the level of voltage unbalance on

the power system, the motor load, the impedance of the power system, and any reactors

or harmonic filters on the drive. The diode bridge converter that converts AC-to-DC is

sometimes just referred to as a converter. The converter that converts the DC back to

AC is also a converter, but to distinguish it from the diode converter, it is usually

referred to as an “inverter”. It has become common in the industry to refer to any DC-to-

AC converter as an inverter.

When we close one of the top switches in the inverter, that phase of the motor is

connected to the positive DC bus and the voltage on that phase becomes positive. When

we close one of the bottom switches in the converter, that phase is connected to the

negative DC bus and becomes negative. Thus, we can make any phase on the motor

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become positive or negative at will and can thus generate any frequency that we want.

So, we can make any phase be positive, negative, or zero.

VFD’s do not produce a sinusoidal output. It produces a rectangular output. This

rectangular waveform would not be a good choice for a general purpose distribution

system, but is perfectly adequate for a motor.

If we want to reduce the motor frequency to 30 Hz, then we simply switch the inverter

output transistors more slowly. But, if we reduce the frequency to 30Hz, then we must

also reduce the voltage to 240V in order to maintain the V/Hz ratio.

CHAPTER 6

HVAC SYSTEM

Heating, Ventilation and Air Conditioning (HVAC) system

HVAC based on the principles of thermodynamics, fluid mechanics, and heat

transfer. HVAC system is important in the design of medium to large industrial and

office buildings, where safe and healthy building conditions are regulated with respect

to temperature and humidity, using fresh air from outdoors.

In Trischel factory, they use a HVAC system to keep constant condition

throughout the factory. The yarn which is using to knit can be damaged if there are not

appropriate conditions in Warping section and Knitting section. If there is not a good

condition, it is harmful for the needles which are in knitting machines. So they have a

fully ventilated and air conditioned sections for these two processes. Normally they keep

25°C temperature and 65RH humidity in those areas.

Air conditioning

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Chiller system

These systems are given their efficiency advantages. The components of the

chiller are evaporator, compressor, an air- or water-cooled condenser, and expansion

device. Some air cooled chillers offer the flexibility of separating the components for

installation in different locations. Another benefit of a chilled-water applied system is

refrigerant containment. Having the refrigeration equipment installed in a central

location minimizes the potential for refrigerant leaks, simplifies refrigerant handling

practices, and typically makes it easier to contain a leak if one does occur.

Heat can be removed through radiation, convection, or conduction. Refrigeration

conduction media such as water, air, ice, and chemicals are referred to as refrigerants.

A refrigerant is employed either in a heat pump system in which a compressor is used to

drive thermodynamic refrigeration cycle, or in a free cooling system which uses pumps

to circulate a cool refrigerant.

Refrigerant cycle

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The refrigeration cycle uses four essential elements to cool. The system

refrigerant starts its cycle in a gaseous state. The compressor pumps the refrigerant gas

up to a high pressure and temperature. From there it enters a heat exchanger (condenser)

where it loses heat to the outside, cools, and condenses into its liquid phase. The liquid

refrigerant is returned to another heat exchanger where it is allowed to evaporate; hence

the heat exchanger is often called an evaporator. A metering device regulates the

refrigerant liquid to flow at the proper rate. As the liquid refrigerant evaporates it

absorbs heat from the inside air, returns to the compressor, and repeats the cycle. In the

process, heat is absorbed from indoors and transferred outdoors, resulting in cooling of

the building.

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Cooling towers

A cooling tower is a heat rejection device, which extracts waste heat to the

atmosphere though the cooling of a water stream to a lower temperature. In here

they use two cooling towers to cool the condenser water. That can reduce heat by 5

to 10 centigrade.

Chilled-water distribution system

Chilled-water distribution systems transport water used for air conditioning from the

chiller to the air handlers, where the chilled water flows through coils in the ventilation

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air stream. Chilled water can also flow directly to terminal units located in the occupied

space. Another variation is radiant cooling or chilled beams where chilled water flows

through a radiant cooling device. Passive chilled beams provide cooling separate from

the ventilation-air system. Active chilled beams are integrated into a ventilation-delivery

system.

Ventilation Ventilation is the process of changing or replacing air in any space to control temperature or

remove any combination of moisture, odors, smoke, heat, dust, airborne bacteria, or carbon dioxide, and

to replenish oxygen. Ventilation includes both the exchange of air with the outside as well as circulation

of air within the building. It is one of the most important factors for maintaining acceptable indoor air

quality in buildings. Methods for ventilating a building can be divided into mechanical and natural types.

1) Mechanical ventilation

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Mechanical ventilation is provided by an air handler and used to control indoor

air quality. Excess humidity, odors, and contaminants can often be controlled via

dilution or replacement with outside air. However, in humid climates much energy is

required to remove excess moisture from ventilation air.

2) Natural ventilation

Natural ventilation is the ventilation of a building with outside air without the

use of fans or other mechanical systems. It can be achieved with operable windows

or trickle vents when the spaces to ventilate are small and the architecture permits. In

more complex systems, warm air in the building can be allowed to rise and flow out

upper openings to the outside thus causing cool outside air to be drawn into the building

naturally through openings in the lower areas. These systems use very little energy but

care must be taken to ensure comfort. In warm or humid months in many climates

maintaining thermal comfort solely via natural ventilation may not be possible so

conventional air conditioning systems are used as backups. Air-side economizers

perform the same function as natural ventilation, but use mechanical systems in the

forms of fans, ducts, dampers, and control systems to introduce and distribute cool

outdoor air when appropriate.

In Tricshel factory they use both these systems to ventilate air in the factory. Ventilation air in

the factory is a critical thing because the workers in the factory make lot carbon dioxide when the breath

so the polluted air must be sent out from the factory and new air must come in. Also machine in the

factory floor heats the air in the factory. This air should also send out from the factory. In thermodynamics

it says that heated air rises up. So to remove heated air from the factory they have built some spaces on the

roof where heated air can go out from the factory.

CHAPTER 7

WARPING SECTION

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In this process, two distinct sets

of yarns called the warp and the weft are

interlaced with each other to form a

fabric. 'Warp' is the set of yarns that are

laid out first on a loom or frame and

'Weft' is the yarn that is woven under

and over the warp yarns that are already

stretched onto the loom. Thus warp is

the continuous row of yarns and the

wefts are the yarns that are woven in

from side to side.

Methods of Warping

Most of the knitting firms prefer to prepare their own warping equipment and

warp beams independently. Mostly, they select the standard types of yarns and warp

effect yarns in the plant. There are two basic methods of warping that can be used to

prepare the warps for the knitting machines- Indirect Warping and Direct Warping.

Indirect Warping is the yarns from the yarn packages are wound onto an intermediate

cylinder (mill) in many parallel groups with a specified density, and then they are back

wound onto the warp beam. In here they use indirect warping method.

Warping Defects

In this warping process we have to face many defects. Those are lapped ends,

bulges, Brocken ends on the beam, yarn cut at the butts of the warp beam, excessive or

insufficient number of yarn ends, conical winding on the beam, slacks and irregular yarn

tension.

Ex:-

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Bulges

Yarn ends are drawn from the middle and the broken end is not correctly pieced up to

the adjoining yarn.

Broken ends on the beam

It occurs due to reasons mentioned in the above point. A group of ends is broken and

tied as a bunch or worked-in with overlapping.

Yarn cut at the butts of the warp beam/ slackness of extreme yarns

It occurs when the reed is improperly set with respect to the warp beam flanges or there

is a deformation of the warp beam flange.

Excessive or insufficient number of yarn ends

The number of yarn ends of the beam becomes excessive or insufficient due to the

incorrect number of bobbins in warping.

Conical winding on the beam

It occurs due to incorrect load applied by the pressure roller.

Slacks & irregular yarn tension

It happens due to any one of these reasons-improper threading of the yarn into the

tension devices, ejection of yarn from under the disc of the yarn tensioning device, or

yarn tension devices of poor quality.

Electro Static on the Yarn Sheet during Warping Process

The surface of isolated material such like polyester yarn, nylon yarn, elastomeric

yarn or others synthetic material is normally not charged. When the yarn surface moves

towards another material, or get frictions with others parts surface on warping machine

during warping process

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E.g.-: a yarn sheet moving on reed, tension tube or ceramic eye let, electrons can be

transported from the surface layer of these part to the yarn sheet.

The surface layer of one material becomes positively charged and the other one

negatively charged. As the yarn sheet and warping parts is isolated, the charge cannot be

conducted away through the yarn or parts which get friction with the yarn sheet itself,

the charge is then called static electricity. The ability of the electric charge to attract one

with the opposite polarity or to repel another with the same polarity may then cause

problems,

E.g.-: Broken filaments on the yarns, hairness or the yarn sticky together.

Warping machine static application

In the warping machine, the string unfastened from the rollers gets static charges

along the way from the out of the warp to the twisting combs. These static charges make

thinner strings round and break. Then, this causes the breakdowns of the machine and

loss of the time and working.

Since the ionization pins are directed to the strings, Antistatic bars should be

positioned under the out of the warping. Thus, the bars neutralize the static charges on

the strings and solve the problems created by the static. Also, antistatic bars can be put

at the out of the combs for the neutralization of the combing area.

Broken filament.

Un-even warp beam surface.

Different outer circumference in one set of warp beam, mostly for textured yarn.

Yarn hainess.

Short life time of the latch needle for the warp knitting machine used latch needle.

The charged surface of the yarn sheet can be neutralized by ionizing the air uses anti-

static equipment or electro static discharger (ESD), i.e. air particles are charged by

positive and negative polarity.

The negatively charged air particles can then give off an electron to a positively charged

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particle in the surface of an isolated material, thereby neutralizing particles both in air

and material. In the same way the positive air particles are neutralized by the negative

particles in a charged material.

The anti-static equipment uses a high voltage electrode to ionize air particles through

corona discharge to both positive and negative polarity.

Picture 1,showing the ESD rod installed below the yarn sheet after every separator reed

on warping machine.

Picture 2,showing the ESD installed below the yarn sheet before and after main reed

,before the yarn sheet warp onto the beam.

Oil bathing

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CHAPTER 8

KNITTING SECTION

Process map of the Knitting section

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Knitting

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Knitting is a method by which thread or yarn is used to create a cloth. Knitted fabric

consists of a number of consecutive rows of loops, called stitches. As each row progresses, a

new loop is pulled through an existing loop. The active stitches are held on a needle until

another loop can be passed through them. This process eventually results in a fabric, often used

for garments.

Different types of yarns and needles may be used to achieve a plethora of knitted materials;

these tools give the final piece a different texture, weight, and/or integrity. Other factors that

affect the end result include the needle's shape, thickness and malleability, as well as the yarn's

fiber type, texture and twist.

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Courses and wales

Like weaving, knitting is a technique for producing a two-dimensional fabric made from

a one-dimensional yarn. In weaving, threads are always straight, running parallel either

lengthwise (warp threads) or crosswise (weft threads). By contrast, the yarn in knitted fabrics

follows a meandering path, forming symmetric loops symmetrically above and below the mean

path of the yarn. These meandering loops can be stretched easily in different directions, which

give knitting much more elasticity than woven fabrics; depending on the yarn and knitting

pattern, knitted garments can stretch as much as 500%. For this reason, knitting was initially

developed for garments that must be elastic or stretch in response to the wearer's motions,

such as socks and hosiery. For comparison, woven garments stretch mainly along one direction

and are not very elastic, unless they are woven from stretchable material such as spandex.

Knitted garments are often more form-fitting than woven garments, since their elasticity

allows them to contour to the body's outline more closely; by contrast, curvature is introduced

into most woven garments only with sewn darts, flares, gussets and gores, the seams of which

lower the elasticity of the woven fabric still further. Extra curvature can be introduced into

knitted garments without seams, as in the heel of a sock; the effect of darts, flares, etc. can be

obtained with short rows or by increasing or decreasing the number of stitches. Thread used in

weaving is usually much finer than the yarn used in knitting, which can give the knitted fabric

more bulk and less drape than a woven fabric.

Weft and warp knitting

Warp knitting

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Weft knitting

There are two major varieties of knitting: weft knitting and warp knitting. In the more

common weft knitting, the wales are perpendicular to the course of the yarn. In warp knitting, the

wales and courses run roughly parallel. In weft knitting, the entire fabric may be produced from a

single yarn, by adding stitches to each wale in turn, moving across the fabric as in a raster scan.

By contrast, in warp knitting, one yarn is required for every wale. Since a typical piece of knitted

fabric may have hundreds of wales, warp knitting is typically done by machine, whereas weft

knitting is done by both hand and machine. Warp-knitted fabrics such as tricot and milanese are

resistant to runs, and are commonly used in lingerie.

Weft-knit fabrics may also be knit with multiple yarns, usually to produce interesting color

patterns. The two most common approaches are intarsia and stranded color work. In intarsia,

the yarns are used in well-segregated regions, e.g., a red apple on a field of green; in that case,

the yarns are kept on separate spools and only one is knitted at any time. In the more complex

stranded approach, two or more yarns alternate repeatedly within one row and all the yarns

must be carried along the row, as seen in Fair Isle sweaters. Double knitting can produce two

separate knitted fabrics simultaneously, e.g., two socks; however, the two fabrics are usually

integrated into one, giving it great warmth and excellent drape.

CHAPTER 9

DYING SECTION

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CHAPTER 10

FINISHING SECTION

Process map of the finishing department

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Stenter machine

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Stenter machine is the most important machine when the considering the quality

of the fabric. It can control specific properties of the fabric like GSM value, shrinkage,

spirility. Etc.

Machine diagram and parts

1. Vender part

2. Unwinding

3. Fabric accumulator

4. Padder

5. Compensating/dancing roller

6. Entry stand

7. Introduction

8. Chain rail with superstructure

9. Transport chain

10. Dryer

11. Width adjustment

12. Exhaust air fan

13. Heat recovery

14. Exit stand

15. Batcher

16. Plaiter

17. Rollers

18. Reserve

19. Reserve

Working Procedure of Stenter Machine

The fabric is collected from the batcher to the scray and then it is passed

through the padders where the finishes are applied and sometimes shade variation is

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corrected. The fabric is entered into the mahlo (straightener) the function of the mahlo

is to set the bow and also weave of the fabric is gripped by the clips and pins are also

provided but the pins has a disadvantage that they pins make holes at the selvedge but

the stretching of the pins are greater than the clips. These clips and pins are joined to

endless chain. There are 8 to 10 chambers provided on the machine each chamber

contains a burner and filters are provided to separate dust from air. The circulating fans

blow air from the base to the upper side and exhaust fans sucks all the hot air within

the chambers. Attraction rollers are provided to stretch the warp yarn.

After stentering we can increase the width of the fabric up to 1.5-2 inch. The speed of

the machine is about 7-150 m/min.3 meters fabric can run in each chamber.

Temperature is adjusted that according to the fabric as for GSM and other properties.

Solenoid valve

A solenoid valve is an electromechanically operated valve. The valve is controlled by

an electric current through a solenoid: in the case of a two-port valve the flow is switched on or

off; in the case of a three-port valve, the outflow is switched between the two outlet ports.

Multiple solenoid valves can be placed together on a manifold.

Solenoid valves are the most frequently used control elements in fluidics. Their tasks are to shut

off, release, dose, distribute or mix fluids. They are found in many application areas. Solenoids

offer fast and safe switching, high reliability, long service life, good medium compatibility of

the materials used, low control power and compact design.

Besides the plunger-type actuator which is used most frequently, pivoted-armature actuators and

rocker actuators are also used.

Operation

There are many valve design variations. Ordinary valves can have many ports and fluid paths. A

2-way valve, for example, has 2 ports; if the valve is closed, then the two ports are connected

and fluid may flow between the ports; if the valve is open, then ports are isolated. If the valve is

open when the solenoid is not energized, then the valve is termed normally open (NO.).

Similarly, if the valve is closed when the solenoid is not energized, then the valve is

termed normally closed. There is also 3-way and more complicated designs. A 3-way valve has

3 ports; it connects one port to either of the two other ports (typically a supply port and an

exhaust port).

Solenoid valves are also characterized by how they operate. A small solenoid can generate a

limited force. If that force is sufficient to open and close the valve, then a direct acting solenoid

valve is possible. An approximate relationship between the required solenoid force Fs, the fluid

pressure P, and the orifice area A for a direct acting solenoid value is

36

Where d is the orifice diameter. A typical solenoid force might be 15 N (3.4 lbf). An application

might be a low pressure (e.g., 10 pounds per square inch (69 kPa)) gas with a small orifice

diameter (e.g., 3⁄8 in (9.5 mm) for an orifice area of 0.11 sq in (7.1×10−5 m2) and approximate

force of 1.1 lbf (4.9 N)).

In some solenoid valves the solenoid acts directly on the main valve. Others use a small,

complete solenoid valve, known as a pilot, to actuate a larger valve. While the second type is

actually a solenoid valve combined with a pneumatically actuated valve, they are sold and

packaged as a single unit referred to as a solenoid valve. Piloted valves require much less

power to control, but they are noticeably slower. Piloted solenoids usually need full power at

all times to open and stay open, where a direct acting solenoid may only need full power for a

short period of time to open it, and only low power to hold it.

CHAPTER 11

PLC (Programmable Logic Controller)

Programmable Logic Controller (PLC)

A PLC (Programmable Logic Controller) is a device that was invented to replace

the necessary sequential relay circuits for machine control. The PLC works by looking

at its inputs and depending upon their state, turning on/off its outputs. In general every

PLC has three main components, Inputs outputs and the CPU. The CPU (central

processing unit) is the most important element as it able to accept command from the

inputs process from using the program design on a computer then sent information to the

outputs to be executed. The CPU act as a hub for all the activity that appears in a PLC.

That output signal also can be a current or voltage signal.

Process of a PLC

37

Mechatronic system

Main components of a PLC

38

Inputs are used to translate signals for the CPU to process. Process inputs must

be connected to the PLC inputs. For example one process input can be a push button

switch. When the button is pressed it sends electrical signal to the PLC inputs. This

signal can be a current or a voltage signal. This electrical signal is then pass through the

PLC inputs and turns into logical data. Because the CPU is a computer system and it

cannot process from electrical signals. Once the CPU has process the data, the data is

sending through outputs. Outputs are used to translate the CPU logical data back into

electrical signals for use in the industrial processes.

PLC program execution

The software development process for PLC’s

The five IEC 1131-3 (1993) languages arranged according to the

software development process for PLC’s:

SFC, Sequential

Function Chart

(AS, Ablaufsprache)

ST, Structured Text

FBD, Function Block

Diagram

(FUP, Funktionsplan)

39

IL, Instruction List

(AWL, Anweisungsliste)

LD, Ladder Diagram

(KOP, Kontaktplan)

Fields of application for the PLC languages

LD: Derived from the pre-PLC relay based controls. For instance

used for the tool handling in the FANUC machine control

ST: Good for former C programmers

FBD: Drawing functions blocks to express logics (like and/or/not)

analog to signal flows observed in electronic circuit diagrams

(Stromlaufplan).

IL: Old language, many experienced users, a lot of generated

code in use in industry, hard to maintain, hard to read for

externals, hard to handle in larger projects, fast, minimal

memory usage, no programming structure.

SFC: chemistry

LD, Ladder Diagram

Derived from the pre-PLC relay based controls

— low level language

— graphical language

— SIEMENS: LAD/KOP

— Ladder: ‘Leiter’