research.kanchiuniv.ac.inresearch.kanchiuniv.ac.in/final study material pdf/1.basic civil and...

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SCSVMV UNIVERSITY

(University u/s 3 of UGC act 1956) Enathur, Kanchipuram-631561, Tamilnadu, India

Department of Mechanical Engineering Syllabus to be followed

Course YEAR/Sem/class Subject code Total credits

BE (all branches) I/I or II EBU12DT095 2

BASIC CIVIL AND MECHANICAL ENGINEERING

PART B - MECHANICAL ENGINEERING

UNIT – I(7 HRS) BOILERS Classification - Principles of Low pressure steam generators – simple Vertical Boiler, Cochran Boiler, Locomotive Boiler, Lancasier Boiler, Bop-cock Wilcox Boiler

POWER PLANTS

Layout of Steam, gas turbine, diesel, nuclear and hydropower plants. NEW SOURCES OF ENERGY Study of different types of alternative energy sources - Solar, Wind, Wave, Tidal and Geo - thermal. UNIT - II(8 HRS) INTERNAL COMBUSTION ENGINES- Working principles of petrol and diesel Engines - Two stroke and four stroke cycles-Function of main components - single jet carburetion - ignition. Cooling and lubrication systems - fuel pump and injector. METAL CASTING PROCESS Patterns - Types of patterns - Pattern materials - pattern allowances - Molding sand - Properties of molding sand - types of molding - preparation of Green sand mould for casting - melting of cast iron in cupola only - casting defects. UNIT - III(8 HRS) METAL FORMING PROCESS- Principles of forging. Rolling -drawing and extrusion. METAL JOINING PROCESS Principles of welding - fundamental of arc welding. Gas welding and gas cutting - Brazing and soldering. METAL MACHINING PROCESS Types of lathes - Main components and the functions of a centre lathe - operations - cutting tools - drilling machines. TEXT BOOKS . 1..Basic Mechanical Engineering - K.Venugopal,

Anuradha agencies,Kumbakonam. REFERENCE BOOKS . 1.. Basic Civil and Mechanical Engineering - G. Shanmugam and

M.S. Palanichamy, Tata McGraw Hill Publishing Co., 1993.

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STUDY MATERIAL FOR BASIC MECHANICAL

ENGINEERING

CONTENTS

Unit-1 Boilers and power plants

1.1 Boilers-1

1.1.1 Boilers 6

1.1.2 Types of boilers 7

1.1.3 Simple vertical boiler 8

1.1.4 Cochran boiler 10

1.2 Boilers-2

1.2.1 Lancashire boiler 14

1.2.2 Locomotive boiler 16

1.2.3 Wilcox and Babcok Boilers 18 1.3 Sources of energy and power plants

1.3.1 Classification of energy resources 22

1.3.2 Comparison of sources of energy 24

1.3.3 Classification of power plants 25 1.4 Conventional power plants-1 Steam and Gasturbine powe r plants

1.4.1 Steam power plant 26

1.4.2 Gas turbine power plant 31 1.5 Conventional power plants-2

1.5.1 Diesel power plant 35

1.5.2 Hydroelectric power plant 37

1.5.3 Nuclear power plant 39 1.6 Non-Conventional powe r generating system using newable sources of Energy-1

1.6.1 Solar power plant 44

1.6.2 Wind power generation 47

1.7 Non-Conventional powe r generating system using newable sources of Energy-2

1.7.1 Tidal power enrgy generation 51

1.7.2 Geo thermal power plant 53

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Unit-2 Internal Combuston Engines and Metal casting process

2.1 Internal Combustion Engines –Introduction and Construction 2.1.1 Engine construction 55

2.1.2 Components of internal combustion engine 56

2.1.3 Classification of internal combustion engines 58

2.2 Internal Combustion Engines- four stroke and two stroke petrol and diesel engines

2.2.1 Four stroke petrol engine 60

2.2.2 Four stroke diesel engine 61

2.2.3 Two stroke cycle engines 62

2.2.4 Comparison between 2S and 4S engines 64 2.3 Internal Combustion Engines-Fuel injectin systems in petrol and diesel engines

2.3.1 Fuel injection system for petrol engines 66

2.3.2 Fuel ignition system 67

2.3.3 Diesel engine fuel supply parts 71 2.4 Internal Combustion Engines-Cooling system and lubrication system

2.4.1 Cooling system 74

2.4.2 Types of cooling system 75

2.4.3 Lubrication system 78

2.4.4 Types of lubricants 79

2.4.5 Engine lubrication system 79 2.5 Metal casting process

2.5.1 Introduction 84

2.5.2 Sand moulding 85

2.5.3 Gating system 86

2.5.4 Melting and pouring 87

2.6 Patte rn making and moulding processs

2.6.1 Pattern making 88

2.6.2 Sand moulding 91

2.6.3 Types of moulding processes. 92

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2.7 Casting defects

2.7.1 Casting defects 99

2.7.2 Cleaning 102

2.7.3 Inspection 102 2.8 Cupola furnace

2.8.1 Various melting furnaces 103

2.8.2 Cupola Furnace 103

2.8.3 Varous zones in cupola 104

2.8.4 Working of cupola 105

Unit-3 Metal Forming,metal Joining and Metal machining Processes.

3.1 Metal forming Principles and Introduction

3.1.1 Overview of Metal forming 109

3.1.2 Temperature in metal forming 110

3.1.3 Frictional effects 111

3.1.4 Classification of bulk deformation processes 113 3.2 Bulk deformation processes-Rolling and Forging

3.2.1 Rolling 115

3.2.2 Forging 119 3.3 Bulk deformation processes-Extrusion and wire drawing

3.3.1 Extrusion 124

3.3.2 Wire and bar drawing 126 3.4 Metal Joining processes-Gas welding and gas cutting

3.4.1 Metal joining 128

3.4.2 Fusion welding 128

3.4.3 Gas welding 128

3.4.4 Gas welding equipment 129

3.4.5 Mechanism of gas welding 131

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3.4.6 Gas/Flame cutting 133

3.4.7 Filler rods 133

3.5 Metal Joining processes-Arc welding and other processes

3.5.1 Different types of arc welding 136

3.5.2 Arc welding equipments 138

3.5.3 Comparison between DC arc welding and Ac arc welding 140

3.6 Metal Joining processes-Brazing and soldering

3.6.1 Brazing 141

3.6.2 Soldering 142

3.6.3 Preparatory cleaning for brazing and soldering 142

3.6.4 Fluxes for brazing and soldering 142 3.7 Metal Machining processes-Lathe

3.7.1 Types of lathes 144

3.7.2 Components of Lathe 146

3.7.3 Lathe operations 148 3.8 Metal Machining processes-Drilling machines

3.8.1 Drilling 151

3.8.2 Drilling machines 152

3.8.3 Components of Drilling machines 154

3.8.4 Drill materials 155

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STUDY MATERIAL

Course Year / Sem / Class Sub.Code Total Credits

BE (All branches) I / II EBU12DT095 2

Sub: Basic Mechanical Engineering

Lesson No: <1> Module / Unit No: <1> No. of Lecture Hours: <7>

Title: <BOILERS-1>

Objective of the Lesson:

<To gain knowledge about various steam generators or boilers.>

Methodology:

0 – 15Minutes : Introduction to boilers and a brief discussion about boilers

16 – 30 Minutes : Simple vertical boiler and their parts

31 – 45 Minutes : Cochran boiler and its working

46– 50 Minutes : Attendance & closure of class

Brief Content:

Introduction to boilers and a brief discussion about boilers

: Simple vertial boiler and their parts

Cochran boiler and its working

Detailed Content

1.1.1 Boilers:

This part contains the detailed notes of the terminologies, considerations, about varius boilers

Boiler, also known as steam generator, is a closed vessel in which water is

converted into steam above atmospheric pressure by the application of heat. The steam is

used for driving prime movers like steam engines or steam turbines for power generation. It

is also used for producing process steam as in the case of textile industries for sizing,

bleaching, etc., or other industries like paper, sugar and chemical industries. The capacity of

boilers used for power generation is considerably large compared with other boilers.

The primary requirements of a boiler are as follows:

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Water must be very safely contained

Steam must be delivered safely at the required temperature pressure and at the

required rate

Maximum heat produced by the fuel in the furnace should be utilised for

economy It should be accessible for inspection

It should rapidly meet the changes in load.

1.1.2 Types of boilers

Boilers can be classified as follows:

I. According to the flow of water and hot gases - Fire tube (or smoke tube) and Water tube boilers.

In fire tube boilers, hot gases pass through tubes which are surrounded with water. Examples: Vertical, Cochran, Lancashire and Locomotive boilers. There may be single tube as in the case of Lancashire boiler or there may be a bank of tubes as in a Locomotive boiler.

In water tube boilers, water circulates through a large number of tubes and hot

gases pass around them. e.g. Babcock & Wilcox Boiler.

II. According to the axis of the shell - Vertical and Horizontal boilers.

III. According to location or position of the furnace - Externally and Internally fired boilers.

In internally fired boilers, the furnace forms an integral part of the boiler structure. The

Vertical tubular, Locomotive and the Scotch marine boilers are well known examples.

Externally fired boilers have a separate furnace built outside the boiler shell and usually

below it. The horizontal return tube (FIRT) boiler is probably the most widely

known example of this type.

IV. According to the application - Stationary and Mobile boilers. A stationary boiler is one which is installed permanently on a land installation. A marine boiler is a mobile boiler meant for ocean cargo and passenger ships with an inherent fast steaming capacity. V. According to steam pressure - Low, medium and high pressure boilers

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1.1.3 S I M P L E V ER T I C A L BO I L ER

Figure shows the simplest form of an internally fired vertical fire-tube boiler. It does not require heavy foundation and requires very small floor area.

i. Cylindrical Shell

The shell is vertical and is attached to the bottom of the furnace. Greater portion of the shell is full of water which surrounds the furnace also. Remaining portion is steam space. The shell may be of about 1.25 metres diameter and 2. 0 metres height.

ii. Cross-tubes

One or more cross tubes are either riveted or flanged to the furnace to increase

the heating surface and to improve the water circulation.

iii. Furnace (or Fire box)

Combustion of coal takes place in the furnace (fire box).

iv. Grate

It is placed at the bottom of the fire box and coal is fed on it for burning.

v. Fire Door

Coal is fed to the grate through the fire door.

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vi. Chimney (or Stack)

The chimney (stack) passes from the top of the fire box through the top of the shell.

vii. Manhole

It is provided on the top of the shell to enable a man to enter into it and inspect and repair the boiler from inside it. It is also, meant for cleaning the interior of the boiler

shell and exterior of the combustion chamber and stack (chimney).

viii. Hand holes

These are provided in the shell opposite to the ends of each cross tube for cleaning

the cross tubes.

ix. Ashpit

It is provided for collecting the ash deposit, which can be removed away at intervals.

Working:

The fuel (coal) is fed into the grate through the fire hole and is burnt. The ashpit

placed below the grate collect the ashes of the burning fuel. The combustion gas flows

from the furnace, passes around the cross tubes and escapes to the atmosphere through the

chimney. Water goes by natural circulation due to convection currents, from the lower end

of the cross tube and comes out from the higher end. The working pressure of the simple

vertical boiler does not exceed 70 N/cm2.

The following mountings are fitted in the boiler:

Pressure Gauge : It indicates the pressure of the steam inside the boiler.

Water Gauge : This indicates the water level in the boiler.

(Water level indicator)

Safety valve : It prevents an increase of steam pressure in the boiler

above its design pressure.

Steam stop valve : It regulates the flow of steam supply to requirements

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1..1.4 COCHRAN BOILER

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It is a "multi-tubular vertical fire tube boiler" having a number of horizontal fire tubes. It is the modification of a simple vertical boiler where the heating surface has been increased by

means of a number of fire tubes.

It consists of

Shell

It is hemispherical on the top, where space is provided for steam.

Grate

It is placed at the bottom of the furnace where coal is burnt.

Fire Box (Furnace)

It is also dome-shaped like the shell so that the gases can be deflected back till they

are passed out through the flue pipe to the combustion chamber.

Flue Pipe

It is a short passage connecting the fire box with the combustion chamber.

Fire Tubes (F)

A number of horizontal fire tubes are provided, thereby the heating surface is increased.

Combustion Chamber

It is lined with fire bricks on the side of the shell to prevent overheating of the boiler.

Hot gases enter the fire tubes from the flue pipe through the combustion chamber.

Chimney

It is provided for the exit of the flue gases to the atmosphere from the smoke box.

Manhole

It is provided for inspection and repair of the interior of the boiler shell.

Normal size of a Cochran boiler: Shell diameter - 2.75 metres

Height of the shell - 6 metres

Working

Coal is fed into the grate through the fire hole and burnt. Ash formed during burning is

collected in the ashpit provided just below the grate and then it is removed manually.

The hot gases from the grate pass through the flue pipe to the combustion chamber.

The hot gases from the combustion chamber flow through the horizontal fire tubes

and transfer the heat to the water by convection.

The flue gases coming out of fire tubes pass through the smoke box and are

exhausted to the atmosphere through the chimney.

Smoke box is provided with a door for cleaning the fire tubes and smoke box.

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The following mountings are fitted to the boiler:

Pressure Gauge : This indicates the pressure of the steam inside the boiler.

Water Gauge : This indicates the water level in the boiler. The water level in the

boiler should not fall below a particular level, otherwise the

boiler will be overheated and the tubes may burn out.

Safety Valve : The function of the safety valve is to prevent an increase of steam

pressure in the boiler above its normal working pressure.

Steam Stop Valve : It regulates the flow of steam supply to requirements.

Blow-off Cock : It is located at the bottom of the boiler. When the blow-off cock

is opened during the running of the boiler, the high pressure

steam pushes (drains) out the impurities like mud, sand, etc., in

the water collected at the bottom.

Fusible Plug : It protects the fire tubes from burning when the water level in the

boiler falls abnormally low.

Salient Features:

1. The dome shape of the furnace causes the hot gases to deflect back and pass through

the flue. The unburnt fuel if any will also be deflected back.

2. Spherical shape of the top of the shell and the fire box gives higher area by

volume ratio. 3. It occupies comparatively less floor area and is very compact. 4. It is well suited for small capacity requirements

Expected learning outcome: To understand the purpose of boiler ,its construction and the funtioning of simp;e

vertical boiler ,cochran boiler and their merits and limtations.

Questions

1. Define steam generator? 2. What is the purpose of boiler?

3. What are the types of boilers used in the industries? 4. Give some primary requirements of boilers?

5. What are the main parts of the boilers? 6. What is meant by ―GRATE‖ in the boiler? 7. What is the main function of the fusible plug? 8. What are the main functions of the steam stop valve and safety valve? 9. What is the maximum working pressure limit of simple vertical boiler? 10. What are the salient features of Cochran boiler?

11. What are major uses of water gauge and pressure gauge? 12. What are the types of high pressure boilers?

13 Explain in detail of construction and working principle of simple vertical boiler? 14. Explain the construction and working principles of Cochran boiler

with neat sketch? 15.What are the salient features of Cochran boiler?

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STUDY MATERIAL





Title: <BOILERS-2>


<To gain knowledge about more steam generators or boilers.>

Methodology:

0 – 5 Minutes : Review of previous lecture

05 – 25 Minutes : Lancsashire boiler and locomotive boiler.

25 – 45 Minutes : Babcok and Wilcox boiler and its working and its comparison

to other boilers


Brief Content:

Brief review about boilers

Lancsahire boiler locomotive boiler

Babcok and Wilcox boiler and its working

Comparison of water tube boiler with firetube boiler

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Detailed Content:

1.2.1 LANCASHIRE BOILER

It is a stationary, fire tube, internally fired boiler. The size is approximately from 7 -

9 metres in length and 2 - 3 metres in diameter. It consists of:

1. Cylindrical Shell 3. Grate

2. Furnace Tubes, 4. Fire Bridge

Bottom Flue and 5. Dampers

Side Flues

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Cylindrical Shell

It is placed in horizontal position over a brick work. It is partly filled up with water.

The water level inside the shell is well above the furnace tubes.

Furnace Tubes, Bottom Flue and Side Flues

Two large internal furnace tubes (flue tubes) extend from one end to the other end of

the shell. The flues are built up of ordinary Bricks lined with fire bricks. One bottom

flue and two side flues are formed by the brick setting, as shown in the Figure.

Grate

The grate is provided at the front end of the main flue tubes. Coal is fed to the

grate through the fire hole.

Fire Bridge

A brickwork fire bridge is provided at the end of the grate to prevent the flow of

coal and ash particles into the interior of the furnace (flue) tubes. Otherwise the coal

and ash particles carried with gases form deposits on the interior of the tubes and

prevents the heat transfer to the water.

Dampers

Dampers in the form of sliding doors are placed at the end of the side flues to

control the flow of gases from side flues to the chimney flue.

Working

Coal is fed to the grate through the fire hole and is burnt. The hot gases leaving the grate

move along the furnace (flue) tubes up to the back end of the shell and then in the

downward direction to the bottom flue. The bottom of the shell is thus first heated.

The hot gases, passing through the bottom flue, travel up to the front end of the boiler, where they divide into two streams and pass to the side flues. This makes the two sides

of the boiler shell to become heated. Passing along the two side flues, the hot gases travel up to the back end of the boiler to the chimney flue. They are then discharged into the atmosphere through the chimney.

With the help of this arrangement of flow passages of the hot gases, the bottom of the

shell is first heated and then its sides. The heat is transferred to water through the surfaces of the two flue tubes (which remain in water) and the bottom and sides of the shell.

This arrangement of flues increases the heating surface of the boiler to a large

extent. Dampers control the flow of hot gases and regulates the combustion rate as

well as steam generation rate.

The boiler is fitted with necessary mountings. Pressure gauge and water level

indicator are provided at the front. Safety valve, Steam stop valve, Low water and high

steam safety valve and manhole are provided on the top of the shell.

High Steam Low Water Safety Valve:

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It is a combination of two valves. One is lever safety valve, which blows-off steam

when the working pressure of steam exceeds. The second valve operates by

blowing-off the steam when the water level falls below the normal level.

Blow-off cock:

It is situated beneath the front portion of the shell for the removal of mud and

sediments. It is also used to empty the water in the boiler during inspection.

Fusible plug:

It is provided on the top of the main flues just above the grate. It prevents the

overheating of the boiler tubes by extinguishing the fire when the water level falls

below a particular level. A low water level alarm is mounted in the boiler to give

a warning when the water level falls below the preset value.

Salient Features

The arrangement of flues in this boiler increases the heating surface of the shell to

a large extent.

It is suitable where a large reserve of steam and hot water is

needed. Its maintenance is easy.

Super heater can be easily incorporated into the system at the end of the main flue

tubes. Thus overall efficiency of the boiler can be increased.

1.2.2 Locomotive Boiler:

Solid fuel is burned on the grate inside the firebox. The primary air is admitted below

the grate and is drawn to the firebed while the secondary air is admitted through the

firehole door. The firebrick arch lengthens the path of the hot gases from the burning

of the fuel to ensure complete combustion. The hot gases are then drawn through long

tubes in the boiler to the smokebox and out of the locomotive from the chimney.

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The heat from the firebox heats up the water in the boiler. Water is also heated by the heat from

the hot gases going through the long tubes. As water becomes hotter, it turns into saturated steam

which collects above the water. The regulator valve, which controls the passage of the steam to the

cylinders, is situated in the dome. There are also safety valves on top of the boiler to release steam

if the pressure tends to rise to a dangerous level.

The saturated steam flows through the main steam pipe to the superheater header. It then

travels through superheater element pipes in the boiler where it is heated up. After coming out of

these pipes through the superheater header, it will have become superheated steam. The

extremely hot steam then flows through steam pipes to the cylinders where its pressure moves

the pistons which move the wheels of the locomotive.

In the smokebox, exhaust steam passes through the blastpipe to the chimney at high

speed due to the confined vent of the blastpipe. This creates a partial vacuum in the

smokebox which provides the draw of the air to the firebox and ensures that the hot

gases are drawn out of the firebox via the tubes in the boiler.

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1.2.3 BABCOCK AND WILCOX BOILER

It is a water tube boiler used in steam power plants. In this, water is circulated

inside the tubes and hot gases flow over the tubes.

Description:

The Babcock and Wilcox boiler consists of:

i. Steam and Water Drum (Boiler Shell) vi. Baffles

ii. Water Tubes vii. Super heater

iii. Uptake-Header and Down-Comer viii. Mud Box

iv. Grate ix. Inspection Doors

v. Furnace x. Damper

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Steam and Water Drum (Boiler Shell)

One half of the drum which is horizontal is filled up with water and steam remains on

the other half. It is about 8 metres in length and 2 metres in diameter.

Water Tubes

Water tubes are placed between the drum and the furnace, in an inclined position (at an

angle of 10 to 15°) to promote water circulation. These tubes are connected to the uptake-header and the down-corner.

Uptake-Header and Down-Corner ( or Down take-Header)

The drum is connected at one end to the uptake-header by short tubes and at the other

end to the down-corner by long tubes.

Grate

Coal is fed to the grate through the fire door.

Furnace

Furnace is kept below the uptake-header.

Baffles

The fire-brick baffles, two in number, are provided to deflect the hot flue gases.

Superheater

The boiler is fitted with a superheater tube which is placed just under the drum and

above the water tubes.

Mud Box

Mud box is provided at the bottom end of the down-corner. The mud or sediments in the

water are collected in the mud box and it is blown-off time to time by means of a blow-

off cock.

Inspection Door

Inspection doors are provided for cleaning and inspection of the boiler.

Working

Coal is fed to the grate through the fire door and is burnt.

Flow of flue gases: The hot flue gases rise upward and pass across the left-side portion of the water tubes.

The baffles deflect the flue gases and hence the flue gases travel in a zigzag manner (i.e., the

hot gases are deflected by the baffles to move in the upward direction, then downward and

again in the upward direction) over the water tubes and along the superheater. The flue gases

finally escape to the atmosphere through the chimney.

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Water circulation: That portion of the water tubes which is just above the furnace is heated comparatively at

a higher temperature than the rest of it. Water, its density being decreased, rises into the drum

through the uptake-header. Here the steam and water are separated in the drum. Steam being lighter is collected in the upper part of the drum. The water from the drum comes down

through the down-comer into the water tubes. A continuous circulation of water from the drum to the water tubes and water tubes to the drum is thus maintained. The circulation of

water is maintained by convective currents and is known as "natural circulation".

Superheating: Steam is taken from the steam space of the drum through a tube to the superheater.

Steam is superheated, in the superheater, as it receives additional heat. A damper is fitted as shown to regulate the flue gas outlet and hence the draught. The boiler is fitted with necessary mountings. Pressure gauge and water level indicator are mounted on the boiler at its left end. Steam safety valve and stop valve are mounted on the top of the drum. Blow-off cock is provided for the periodical removal of mud and sediments collected in the mud box.

Salient Features

1. Its overall efficiency is higher than a fire tube boiler.

2. The defective tubes can be replaced easily. 3. All the components are accessible for inspection even during the operation.

4. The draught loss is minimum compared with other boilers. 5. Steam generation capacity and operating pressure are high compared with

other boilers. 6. The boiler rests over a steel structure independent of brick work so that the

boiler may expand or contract freely. 7. The water tubes are kept inclined at an angle of 10°- 15° to promote water

circulation.

Advantages and Disadvantages of Water Tube Boilers over Fire Tube Boilers

Advantages:

1. Steam can be generated at very high pressures. 2. Heating surface is more in comparison with the space occupied, in the case of

.water tube boilers. 3. Steam can be raised more quickly than is possible with a fire tube boiler of

large water capacity. Hence, it can be more easily used for variations of load. 4. The hot gases flow almost at right angles to the direction of water flow. Hence

maximum amount of heat is transferred to water. 5. A good and rapid circulation of water can be made.

6. Bursting of one or two tubes does not affect the boiler very much with regard to its working. Hence water tube boilers are sometimes called as "safety boilers".

7. The different parts of a water tube boiler can be separated. Hence it is easier to transport.

8. It is suitable for use in steam power plants (because of the various advantages listed above).

Disadvantages: 1. It is less suitable for impure and sedimentary water, as a small deposit of scale

may cause the overheating and bursting of tubes. Hence, water treatment is very

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essential for water tube boilers.

2. Maintenance cost is high. 3. Failure in feed water supply even for a short period is liable to make the boiler

overheated. Hence the water level must be watched very carefully during operation of a water tube boiler.

Expected learning outcome;

To understand the construction andfunctioning of Lancashire and locomotive boilers

and Babcok and wilcox boiler . and also the appreciate the merits and limitations of each of them and compare firetube boilers with watertube boilers.

Questions 1. Explain the construction and working principles of Lancashre boiler with neat sketch? 2. What are the salient features of Lancashire boiler?

3. Explain in details about the construction and working principles of Babcock and Wilcox boiler? 4. What are the advantages and disadvantages of water tube boilers over fire tube boilers? 5. . Explain the construction and working principles of locomotive boiler with neat sketch?

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STUDY MATERIAL


BE (All branches) I / I&II EBU12DT095 2



Title: <SOURCES OF ENERGY AND POWER PLANTS>


<To gain knowledge about sources of enerrgy and power plants.>

Methodology:

0 – 15Minutes : Sources and classification of fuels

16 – 30 Minutes : Comparison between various types of fuels

31 – 45 Minutes : Inroduction to various types of power plants


Brief Content:

: Sources and classification of fuels

: : Comparison between various types of fuels

Introduction to various types of power plants

1.3.1 Classification of energy resources:

Renewable and Non-renewable sources.

Renewable sources are Hydro-power, Solar energy, Wind energy, Tidal

or Wave energy and Energy from Bio- mass.

Non-renewable sources include Fossil fuels, viz., solid fuels, liquid fuels,

gaseous fuels and nuclear fuel.

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These sources of energy are briefly discussed below:

1. Fossil Fuels

Fossil fuels are classified as solid, liquid and gaseous and as natural or

prepared. a. Solid Fuels:

Naturally occurring solid fuels include wood, varieties of coals, viz., Anthracite,

Bituminous and Lignite (brown coal) while prepared ones include coke, charcoal etc.

b. Liquid Fuels:

Liquid fuels include petroleum and its derivative, namely, Diesel. After the

first and second shocks of oil prices, the power industry in western countries moved

from oil to coal.

c. Gaseous Fuels:

Naturally occurring gaseous fuel is Natural gas which comes o ut of gas

wells and petroleum wells. Producer gas, coal gas and blast furnace gas are prepared

gaseous fuels.

2. Energy stored in water

The potential energy of water at higher level is used for the generation of

electrical power. Apart from being perennial and inexhaustible source of energy. It

represents the cheapest source of energy in our country. Water is renewable source

of energy, as it is neither consumed nor converted into something else.

3. Nuclear energy

Enormous release of energy from a relatively small mass of nuclear fuel like

Uranium makes this source of energy of great interest. The energy liberated by

nuclear fission of one kilogram of U235

is equal to the heat energy obtained by

burning 4500 tonnes of high grade coal.

4. Solar energy

The heat energy contained in the rays of sun is utilised to boil water and

generate steam which can be used to drive prime movers to generate electrical power.

5. Wind energy

Wind energy can be made use of where wind at suitable velocity is available.

6. Tidal or Wave energy

Ocean waves and tides contain large amount of potential energy which is

used for power generation.

7. Geo-Thermal energy

It is the thermal energy naturally available in the form of steam in some part of

the earth below the earth surface. Generally geo-thermal steam is available in volcanic

regions.

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1.3.2 COMPARISON OF SOURCES OF ENERGY

Solid fuels Vs. Liquid fuels:

Solid fuels produce large quantity of ash after burning, whereas liquid fuels leave

no or very little ash after burning.

Liquid fuels require less storage space. But they are costly as compared to solid

fuels. Further they require special type of burners for their burning. Also there is

danger of explosion in the case of liquid fuels.

Solid fuels Vs. Gaseous fuels

Gaseous fuels do not produce ash. Also greater cleanliness is assured as smoke is

practically nil. Handling of gaseous fuels is not required as they can be easily piped

into the furnace. However there is danger of explosion for gaseous fuels.

Availability of source of energy

The steam power plants depend upon coal which is exhaustible. For a hydro- power

plant the availability, of water depends upon the natural phenomenon of rain. Solar,

wind and tidal energies are inexhaustible.

Capacity of power plant:

The capacity of power production of steam or hydro- power plant may be high.

Diesel power plants are of limited generation capacity.

Air pollution and Radiation hazard:

In steam power plants there is nuisance of smoke and air pollution. In nuclear

power plants radio-active waste is a health- hazard. Hydro-power plant has no such

air pollution or waste disposal problem.

Cost:

The capital cost of a steam power plant using coal is less than a hydro-electric power

plant. However, the operating cost of a. steam power plant is higher than that of a hydro- .power plant.

Initial cost of a nuclear power plant is the highest whereas its running cost is perhaps least of all.

Location of power plant:

Steam power stations can be located at the load centre whereas a hydro-power plant has

to be located where water is available in large quantities. The nuclear power plants 'are best suited

for areas far remote from coal reserves and water power.

Renewable resources:

The advantages of renewable resources like hydro power, solar power, wind power and

tidal power are enormously attractive. Of these, hydro-electric power is the best developed,

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providing 8% of the world's energy supply in the form of very cheap electricity

(1/8 and 1/2 of the cost of fossil fuel and nuclear generated electricity).

The major problem associated with renewable resources is our inability to store large

quantities of energy either in the form of heat or as electricity. The diffuse or dilute nature of

renewable resources means that large area of land or ocean is necessary to accommodate solar

collectors, 30 km square for a solar power station or 1000 wind mills with 90 m blades set 250 m

apart to replace the nuclear power plant on a 1 square km site. The use of renewable resources can

only come slowly, as the development of technologies has a very long time scale. It is a fact that the

use of renewable resources such as solar, wind and tidal energy are likely to prove far less

hazardous as compared to the depleting fossil and fissible fuels.

The non-renewable conventional sources of energy like coal, diesel, natural gas, etc.,

will be exhausted by the middle of the next century, if the present rate of power increase and

population increase continue.

As these non-renewable sources are consumed, the mankind must turn its attention to longer-term and permanent type of energy resources. The Scientists and Engineers all over the

world are in search of new non-conventional sources of energy for the last few decades.

These sources, viz., solar, wind, tidal, etc., are considered renewable and non-

exhaustible as these are considered as perpetual sources of

energy. Solar energy and wind energy (to certain extent) show

promise of becoming dependable renewable energy sources.

Power plant is an industrial system composed of machinery, equipment and structures

designed to convert various energy resources into electricity on a large scale.

Power plant is also called as Power station or Power house. 1.3.3 Classification of Power Plants

Expected learning outcome: To know various types of fuels availbale for power generation and ther ava ilability in short and long run.

Questions 1. What are fossil fuels . 2. Compare solid liquid and gaesous fuels. 3. List renewable sources of energy andwhere from they are

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available. 4. How do you classify power plants

STUDY MATERIAL





Title: <CONVENTIONAL POWER PLANTS-1>


<To gain knowledge about various power plants.>

Methodology:

0 – 5Minutes : Introduction to various power plants

05 – 30 Minutes : Steam power plant- its working ,advantages and limitations

35 – 45 Minutes : Gas turbine power plant- its working ,advantages and limitations


Brief Content:

Brief review about various types of power plants

Steam power plant- its working ,advantages and limitations

Gas turbine power plant- its working ,advantages and limitations

Detailed Content:

1.4.1 STEAM POWER PLANT

Steam is used to drive steam engines and steam turbines due to the following reasons:

1. Steam can be raised quickly from water

2. It does not react much with materials.

3. It is stable at temperatures required in the plant

The layout of steam power plant has the following circuits:

1. Fuel (Coal) and ash circuit 2. Air and flue gas circuit 3. Feed water and steam flow circuit 4. Cooling water flow circuit.

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Layout of Steam Power Plant

COAL AND ASH CIRCUIT:

• Coal from mines is delivered by ships, rails or trucks to the power station. • Coal received at coal yard. • Coal is sized by crushers, breakers etc., • The sized coal is stored in coal storage. • From stock yard, the coal is transferred to the boiler furnace by means of

conveyors, elevators etc., • The coal is burnt in the boiler and ash is formed. • Ash coming out of the furnace will be too hot, dusty and accompanied by

poisonous gases. • The ash is transferred to the ash storage. • Generally the ash will be quenched to reduce the temperature and the dust content.

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Air and flue gas circuit:

• Air is taken from the atmosphere by the action of FD fan. • It is passed through an air pre heater • The air is preheated by the flue gases in the pre heater. • This preheated air is supplied to the furnace to aid the combustion of fuel. •

Due to the combustion of fuel the flue gases are formed. • The flue gases from the furnace pass over the boiler tubes and super heater tubes. • Then the flue gases pass through economiser to heat the feed water. • After that it passes through a dust collector. • It is then exhausted to atmosphere through chimney

Water and steam circuit:

• The water is preheated by the flue gases in the economiser. • This preheated water is then supplied to the boiler drum. •

Heat is transferred to the water by the burning of the coal. • Due to this, water is converted into the steam. • The steam raised in boiler is passed through a super heater. • It is superheated by the flue gases. • The turbine drives generator to produce electric power. •

The expanded steam is then passed through the condenser. • In the condenser, steam is condensed into water the re circulated.

Cooling water circuit:

• The exhaust steam from the turbine is condensed in the condenser. • In the condenser, the cold water is circulated to condense the steam into water. • The steam is condensed by losing its latent heat to the circulating the cold water. • Hence the cold water gets heated. • This hot water is then taken to a cooling tower. • In cooling tower the water is sprayed in the form of droplets through nozzles.

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• The atmospheric air enters the cooling tower from the openings provided at the bottom of the tower.

• This cold water is again circulated through the pump, condenser and the cooling • Some amount of water may be lost during circulation. • Hence make up water is added to the pond by means of a pump

Energy conversion process:

Chemical Energy (Fuel/Coal)

Heat Energy (Boiler)

Mechanical Energy (Turbine)

Electrical Energy (Generator)

Advantages of Steam Power Plant (Thermal Plant)

• Life of plant is more (25-30 years ) compared to Diesel plant (2-5 years) • Repair and maintenance cost is low when compared to diesel plant. • Initial cost is less compared to nuclear plant. • Suitable for varying load conditions. • No radioactive harmful wastes are produced • Unskilled operators can operate the plant. • The power generation does not depend on the water storage. • There are no transmission losses, as they are located near load centres.

Disadvantages of Thermal Power Plant

• Less efficient than diesel plants. • Starting up and bringing into service takes more time.

• Cooling water required is more. • Space required is more. • Storage required for the fuel is more. • Ash handling is a big problem • Not economical in areas which are remote from coal fields. • Manpower required is more. • For large units, the capital cost is more.

Factors to be considered for selection of site for thermal power plant:

Availability of coal:

• A thermal plant of 400M, capacity requires nearly 6000 tons of coal every day. • Power plant should be located near coal mines.

Ash Disposal Facilities:

•

•

Ash comes out in hot condition and handling is

difficult. The ash can be disposed into sea or river.

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Water Availability:

• Water consumption is more as feed water into boiler, condenser and for ash disposal. • Water is required for drinking purpose. • Hence plant should be located near water source.

Transport Facility:

• Railway lines or other mode of transport for bringing heavy machineries for installation also for bringing coal.

Public Problems:

• The plant should be far away from residential area to avoid nuisance from smoke, fly ash and noise.

Nature of Land:

• Many power plants have failed due to weak foundations. • Land (soil) should have good bearing capacity to withstand dead load of plant.

Thermal power plants in Tamil Nadu:

• Neyveli • Tuticorin

• Ennore

• Mettur

Pollution caused by thermal power plant (steam power plant):

• Main pollutants from thermal plants are SO2, CO2, CO as minute particles such as

fly ash. • SO2 causes suffocation, irritation to throat and eyes and respiratory for people.

It destroys crop. • CO is a poisonous gas. • Dust particles cause respiratory troubles like cough, cold, sneezing etc.,

Thermal Pollution:

• Thermal plants produce 40 million kJ of heat to the environment through condenser water and exhaust gases.

• Thermal pollution of atmosphere can be reduced using the low grade energy exhausted steam.

Noise Pollution:

• The sources of noise in a power plant are turbo alternators, fans and power transformers. • Sound proofing can be done to reduce the noise.

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1.4.2 GAS TURBINE POWER PLANT

a) L. P. Air Compressor:

Atmospheric air is drawn in and passed through the air filter. It then flows into the low

pressure compressor. Major percentage of power developed (66%) by the turbine is used

to run the compressor. The power required to run the compressor can be reduced by

compressing the air in two stages, i.e., in low pressure and high pressure compressors

and also by incorporating an intercooler between the two.

b) Intercooler:

Intercooler is used to reduce the work of the compressor and increase the efficiency. The

energy required to compress air is proportional to the air temperature at inlet. Therefore if

intercooling is carried out between the stages of compression, total work can be reduced.

c) H. P. Compressor:

From the intercooler, the compressed air enters the high pressure compressor, where it

is further compressed to a high pressure. Then it is passed into the regenerator.

d) Regenerator:

In the simple open cycle system the heat of the turbine exhaust gases goes as waste. To

make use of this heat a regenerator is provided. In the regenerator the heat of the hot exhaust

gases from the turbine is used to preheat the air entering the combustion chamber.

e) Combustion Chamber:

Hot air from regenerator flows to the combustion chamber. Fuel (natural gas or coal gas

or kerosene or gasoline) is injected into the combustion chamber and burns in the stream

of hot air. The products of combustion, comprising a mixture of gases at high

temperature and pressure are passed to the turbine.

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f) Gas Turbines:

Products of combustion are expanded in high pressure turbine and then in low pressure

turbine. The part of the work developed by the gases passing through the turbines is used to

run the compressor and the remaining (about 34%) is used to generate electric power.

Open cycle and Closed cycle systems:

When the heat is given to the air by mixing and burning the fuel in the air and the gases

coming out of the turbine are exhausted to the atmosphere, the cycle is known as "open

cycle system". If the heat to the working medium (air or any other suitable gas) is given

without directly burning the fuel in the air and the same working medium is used again

and again, the cycle is known as "closed cycle system".

g) Reheating Combustion Chamber:

The output of the plant can be further improved by providing a reheating combustion

chamber between high pressure and low pressure turbines. In this, fuel is added to reheat

the exhaust gases of high pressure turbine.

The addition of the regenerator, intercooler and reheating combustion chamber increases

the overall efficiency of the plant.

Advantages of Gas Turbine Power Plant

1. Natural gas is a very suitable fuel and where this is available cheap, it is an ideal

source of power in gas turbine.

2. Gas turbine plant is smaller in size and weight compared to an equivalent steam power

plant. For smaller capacities the size of the gas turbine power plant is appreciably

greater than a high speed diesel engine plant; but for larger capacities it is smaller in

size than a comparable diesel plant. If size and weight are the main considerations such

as in ships, aircraft engines and locomotives, gas turbines are more suitable.

3. The initial cost is lower than an equivalent steam plant.

4. It requires less water as compared to a steam plant.

5. It can be started quickly, and can be put on load in a very short time.

6. Maintenance cost is low. 7. It does not require heavy foundation and buildings. 8. Any poor quality and wide variety of fuels from natural gas to residual oil or powdered

coal can be used. 9. The running speed of the turbine (40,000 to 100,000 rpm) is considerably large

compared with diesel engine (1000 to 2000 rpm). 10. The exhaust of the gas turbine is free from smoke.

Disadvantages

1. Major part of the work (66%) developed in the turbine is used to drive the

compressor. Therefore network output of the plant is low.

2. It requires special metals and alloys for different components because the

operating temperature (2000°C) and speed (100,000 rpm) are very high. 3. Part load efficiency is poor compared to diesel plant.

Expected learning outcome To know about differen type of power plants and study

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in detail about steam power plant and gasturbine

power plant their advantages ,limitations,cost and

their effects on evironment

Questions 1.Name few pollutants discharged by the thermal power plants?

2.Explain with neat sketch of gas turbines and its cycles. 3.Explain with neat sketch of gas turbines power plant. Mention the advantages and disadvantages. 4.What are the advantages of thermal power plant?\ 5.Explain the steam power plant layout according to the various circuits with neat sketch.

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STUDY MATERIAL


BE (All branches) I /I& II EBU12DT095 2



Title: <CONVENTIONAL POWER PLANTS-2>


<To gain knowledge about more conventional power plants.>

Methodology:

0 – 15Minutes : Diesel power plant

16 – 30 Minutes Hydro-electric power plant- its working ,advantages and

limitations

30 – 45 Minutes Nuclear power plant- its working ,advantages and limitations


Brief Content:

Diesel power plant

Hydroelectric power plant- its working ,advantages and limitations

Nuclear powe plant- its advantages and limitations

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Detailed Content:

1.5.1 DIESEL POWER PLANT

Layout of Diesel Power plant

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Working of Diesel Power plant:

• Air from atmosphere is drawn into the compressor and is compressed. • The compressed air is sent to diesel engine through filter. • In the filter, dust, dirt from air are filtered and only clean air is sent to diesel engine.

• Fuel oil from tank is passed through filter where it gets filtered and clean oil is injected into the diesel engine through fuel pump and fuel injector

• Mixture of compressed air and spray of fuel oil are ignited into the engine and combustion takes place.

• The heat energy is utilized for driving the generator, which produces power.

Main components of a Diesel power

plant: 1. Fuel Supply system

It consists of fuel tank, fuel filter and fuel pump and injector.

2. Air Intake and Exhaust system

It consists of compressor, filter and pipes for the supply of air and pipes for

exhaust gases. In the exhaust system silencer is provided to reduce the noise.

3. Cooling system

Circulates water around the Diesel engines to keep the temp at reasonably

low level.

4. Lubricating system

It includes lubricating oil tank, pump, filters and lubricating oil.

5. Starting system

For initial starting the devices used are compressed air, battery, electric

motor or self-starter.

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1.5.2 HYDRO ELECTRIC POWER

PLANT:

Layout of Hydroelectric power plant

Components of Hydro Electric Power Plant:

Reservoir:

•

•

•

Water is collected during rainy

season It is stored in the reservoir. A dam is built across the river adequate water head.

Penstock:

• It is a passage through which water flows from reservoir to turbine.

Surge Tank:

• It is installed along the penstock (between turbine and reservoir) • To control or regulate the sudden water over flow and to pro tect the penstock

from bursting. • It reduces the pressure and avoids damage to the penstock due to the water hamme

r effect.

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• When the load on the turbine is decreased there will be a back flow, which causes increase or decrease in pressure. It is known as water hammer.

Power House:

• It is building that houses that water turbine, generator, transformer and control room.

Water Turbine:

• Water turbines such as Pelton, Kaplan and Francis are used to convert pressure and kinetic energy of flowing water into mechanical energy.

Draft Tube:

• It is connected to the outlet of the turbine.

Tailrace:

• It refers to the downstream level of water discharged from turbine.

Generator:

• It is a machine used to convert mechanical energy into electrical energy.

Step up transformer:

• It converts the Alternating Current (AC) into high voltage current suitable for transmission.

Working Principle of Hydro Electric Power Plant:

• It uses the potential energy of water of water stored in a reservoir. • The water from the reservoir through a penstock and then forced through nozzle

or nozzles before reaching the turbine. • The hydraulic turbine converts the kinetic energy of water under pressure into

mechanical energy. • The shaft of the turbine is coupled to a generator that generates electricity • The electricity generated is fed to the step-up transformer to increase its voltage. • Power is fed to the transmission lines for distribution. • The output power of Hydel power plant depends on the head of water stored in

the reservoir and the quantity of water discharged

Classification of Hydro Electric Power Plant:

•

•

•

High Head (Water head above 300m)

Medium Head (Water head from 30 to 300m)

Low Head (Water head from 3 to 30m)

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Factors to be considered for the location of hydroelectric Power Plant:

Availability of Water:

• Adequate water must be available with good head.

Cost and type of Land:

• Bearing capacity of the land should be good to withstand huge structures and equipment.

Storage of Water:

• A dam must be constructed to store the large quantity of water in order to cope with variations of water availability throughout the year.

Transportation Facilities:

• The site should be accessible by rail and road for easy transportation of equipment and machinery.

Pumped storage facilities:

• The pumping facilities to reuse the water should be possible.

Merits of Hydro Electric Power Plant:

•

•

•

•

•

Requires no fuels and hence pollution

free. Low operating cost. Simple in construction and requires less

maintenance. Very robust and durable. The reservoir and dam can also be used for irrigation.

Demerits of Hydro Electric Power Plant:

• Very high capital cost • Skilled personnel is required for construction. • High cost of transmission as plant is normally required far off from hilly areas. • Period of delay causes the delay in the commissioning of the plant. • Construction of new hydel plant may need rehabilitation of people and payment

compensation for land acquisition. 1.5.3 NUCLEAR POWER PLANT - LAYOUT

• Nuclear power plant uses nuclear energy from radioactive element for generating electrical energy.

• More than 15% of the world's electricity is generated from Nuclear power plants. • It is generally located far away from populated areas. • In future generation of electricity will be depending on Nuclear Power Plant, as it is

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economical.

• 1 kg of uranium U-235 can produce electrical power electrical that can be produced by using 3000 -4500 tonnes of high grade coal or 2000 tonnes of oil.

Layout of Nuclear Power plant

Components of Nuclear Power Plant:

Nuclear Fuel:

• Normally used nuclear fuel is uranium (U235

)

Fuel Rods:

• The fuel rods hold nuclear fuel in a nuclear power plant. • Neutron Source: A source of neutron is required to initiate the fission for the first time. A

mixture of beryllium with plutonium is commonly used as a source of neutron.

Reactor:

• Nuclear fission takes place in the reactor only. • Nuclear fission produces large quantity of heat. • The heat generated in the reactor is carried by coolant circulated through the reactor

Control Rods:

• They are used to control the chain reaction.

• They are absorbers of neutrons. • The commonly used control rods are made up of cadmium or boron.

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Moderator:

• Moderators are used to slow down the fast neutrons. • It reduces 2 MeV to an average velocity of 0.025 eV. • Ordinary or heavy water are used as moderators.

Fuel Rods:

• The fuel rods hold nuclear fuel in a nuclear power plant.

Neutron Reflectors:

• To prevent the leakage of neutrons to large extent. • In PHWR, the moderator itself acts as reflectors.

Shielding:

• To protect from harmful radiations the reactor is surrounded b a concrete wall of thickness about 2 to 2.5 m.

Nuclear Fission

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• It is a process of splitting up of nucleus of fissionable material like uranium into two or more fragments with release of enormous amount of energy.

• The nucleus of U235 is bombarded with high energy neutrons U

235+0n

1 Ba

141+Kr

92+2.50n

1+200 MeV energy.

• The neutrons produced are very fast and can be made to fission other nuclei of U235, thus setting up a chain reaction.

• Out of 2.5 neutrons released one neutron is used to sustain the chain reaction.

1 eV = 1.6X10-19

joule.

1 MeV = 106 eV

Working Principle of Nuclear Power Plant:

• The heat generated in the reactor due to the fission of the fuel is taken up by the coolant. • The hot coolant then leaves the reactor and flows through the steam generator. •

In the steam generator the hot coolant transfers its heat to the feed water which

gets

converted into steam.

• The steam produced is passed through the turbine, which is coupled with generator. • Hence the power is produced during the running of turbine. • The exhaust steam from the turbine is condensed in the condenser. • The condensate then flows to the steam generator through the feed pump. • The cycle is thus repeated.

Advantages of Nuclear Power Plant:

• Requires less space compared to steam power plant. • Fuel required is negligible compared to coal requirement. • Fuel transport cost is less. • Reliable in operation. • Cost of erection is less. • Water required is very less.

Disadvantages of Nuclear Power Plant:

• Initial Cost is higher. • Not suitable for varying load condition. • Radioactive wastes are hazardous. Hence these are to be handled with much care. • Maintenance cost is higher. • Trained workers are required to operate the plant.

Nuclear Power Plants in India:

•

•

•

•

•

IGCAR, Kalpakkam in Chennai.

Rana Pratap Sagar in Rajasthan

Narora in Uttar Pradesh

Kakarpur near Surat at Gujarat

Kaiga Power Plant at Karnataka

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Expected Learning outcomes. Knowledge principle,construction,working,merits and limitations of diesel

power plant,hydroelectric power plant and nuclear power plants.

Questions 1.What is draft tube? Give its

purpose. 2.Define reservoir?

3.Give the functions of the following parts, i. Surge tank ii. Spill way iii. Tail race 4.Name the classifications of hydro power plants? 5.What is meant by chain reaction? 6.What is meant by nuclear fission?

7.Name the main components of nuclear power plant? 8Explain the diesel power plant with neat sketch? Give some applications. 9.What are the environmental constraints of power generations? Explain any three

10.factors in detail 11.Explain the hydraulic electric power plant layout with neat sketch. 12.Draw and explain in details about the nuclear power plant. Mention the

advantages and disadvantages 13.List out the demerits of diesel engine power plants?.

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STUDY MATERIAL




Lesson No: <6> Module / Unit No: <1> No. of Lecture Hours: <7> Title: < NON-CONVENTIONAL POWER GENERATING SYSTEMS USING

RENEWABLE SOURCES OF ENERGY-1>


<To gain knowledge about solar and wind power plants..>

Methodology:

0 – 5Minutes : Importance of non conventional renewable energy sources.

05 – 30 Minutes : Solar energy systems

31 – 45 Minutes : Wind power energy systems


Brief Content:

: : Importance of non conventional renewable energy

sources Solar energy systems

Wind power energy systems

1.6.1 SOLAR POWER PLANT

Basic Principle of Solar Energy

The sun gives out 3.7 x 1020

MW of energy into space, out of which earth intercepts

only 1.7 x1011

MW. Solar radiation is reduced in intensity in the atmosphere by clouds, dust, haze, and fog.

The energy emitted by the sun in three minutes is equivalent to the world energy

consumption during a year. Most of the energy we receive from the sun comes in the

form of light, a short wave radiation, not all of which is visible to the human eye. When

this radiation strikes a solid or liquid, it is absorbed and transformed into heat energy.

The heat energy is collected in a fluid, generally water. This heat energy can be used in

a solar heater or drier or can be used to run an engine. Flat plate collector or parabolic

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concentrated type collector is used to collect and concentrate the solar energy

and increase the temperature of the working fluid.

Applications of solar energy

1. Solar engines for water pumping. 2. Solar water heaters. Solar 3. cookers. Solar driers. 4. Solar furnaces. 5. Photo-voltaic conversion (solar cells). Solar 6. power generation.

Arrangement of a Solar Power Plant:

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Figure shows a solar power plant with a low temperature solar engine using heated

water from flat plate solar collector and Butane as the working fluid. This was developed

in France for lift irrigation

1. Solar Collectors:

Flat plate collector:

In a flat plate collector, the radiation energy of the sun falls on a flat surface

coated with black paint having high absorbing capacity. It is placed facing the

general direction of the sun. The materials used for the plate may be copper,

steel or aluminium. The thickness of the plate is 1 to 2mm. Tubing of copper

is provided in thermal contact with the plate.

Heat is transferred from the absorber plate to' water which is circulated in

the copper tubes through the flat plate collector.

Thermal insulation is provided behind the absorber plate to prevent heat

losses from the rear surface. Insulation material is generally fibre glass or

mineral wool. The front cover is made up of glass and it is transparent to the

in-coming solar radiation.

Cylindrical parabolic concentrator collector:

Concentrator collectors are of reflecting type utilising mirrors. The reflecting

surface may be a parabolic mirror. The solar energy falling on the collector

surface is reflected and focussed along a line where the absorber tube is

located. As large quantity of energy falling on the collector surface is

collected over a small surface, the temperature of the absorber fluid is very

much higher than in flat plate collector.

While flat plate collectors may be used to heat water up to 80°C (low temperature), the

concentrating type of collectors are designed to heat water to med ium and high

temperature ranges.

2. Butane boiler :

The water heated in flat plate solar collector to 80°C is used for boiling Butane at

high pressure in the Butane boiler. Boiling point of Butane is about 50°C. 3. Turbine:

The Butane vapour generated at high pressure in the boiler is used to run

the vapour turbine which drives the electrical generator.

The vapour coming out of the turbine at low pressure is condensed in a

condenser using water. The condensed liquid Butane is fed back to the

Butane boiler using feed pump.

Advantages

1. Sun is essentially an infinite source of energy. Therefore solar energy is a very large

inexhaustible and renewable source of energy and is freely available all over the world.

2. It is environmentally very clean and is hence pollution-free.

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3. It is a dependable energy source without new requirements of a highly technical

and specialised nature for its wide spread utilization.

4. It is the best alternative for the rapid depletion of fossil fuels.

Disadvantages

1. It is available in a dilute form and is at a low potential. The intensity of solar energy

on sunny day in India is about 1.1 kW/square metre area. Hence very large

collecting areas are required.

2. Also the dilute and diffused nature of the solar energy needs large land area for the

power plant; for instance, about 30 square kilometers area is required for a solar power station to replace a nuclear, plant on a 1 square kilometer site. Hence capital cost

is more for the solar plant. 3. Solar energy is not available at night or during cloudy or rainy days.

1.6.2 WIND POWER GENERATION

The primitive man had to use his muscle power to carry out different works in his attempt of obtaining the necessities of life. The demand for more power and the scarcity of man

power and the ready availability of natural resources like wind, water, etc., might have formed

the reason why the ancient man turned his attention to the utilisation of these resources as

sources of power; thus originated the early prime movers namely wind mill and water wheel.

Principle of Wind Mill

Wind flow is created as an effect of solar heat. Winds are caused due to the

absorption of solar energy on the earth surface and the rotation of earth about its

own axis and around the sun. Because of this, alternate heating and cooling occurs

and difference in pressure is obtained and the air movement is caused.

The flowing wind which has kinetic energy is used to rotate the wind turbine which

is also known as wind mill. Although wind mills have been used for more than a

dozen centuries for pumping water and grinding grains, interest in large scale power

generation had developed over the past 50 years.

The earth's atmosphere is thus a marvellous solar driven heat engine. It is estimated

that roughly 10 millions MW of energy is continuously available in the earth's winds.

Types of Wind Mills

Wind mills are classified as

i. Horizontal axis type and ii. Vertical axis type,

depending on their axis of rotation.

Horizontal axis wind mills are further classified as single-bladed, double-bladed and

multi-bladed types.

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Horizontal axis wind mill with double blade rotor:

In the horizontal axis single blade type, the blade is of propeller type with counter

weight arrangement. The double blade type gives a better performance than the

single blade type.

In the double-blade type, the blade has thick cross section of an aerofoil. At the tip

of the blade, the velocity is about six times the wind velocity. The blade is set at

right angles to the direction of the wind. Ideally the blades should be twisted, but

because of construction difficulties this is not always achieved.

The blade rotor drives a generator through a gear box. It is mounted on a bed

plate attached on the top of the tower

Blade material: The blades are made from aluminium or sheet metal. Not a single large

wind turbine- generator with metal blades has operated for longer than one year

without a blade failure. The suitable material required is a major problem in

developing wind mills of higher power generation capacity.

With rotor, the tower is also subjected to the wind loads which may cause serious

damage. Hence the structure of the tower should be so designed to withstand the

wind load.

The best sites for wind energy are found off-shore and sea coast. The second best

sites are in mountains. The lowest level of wind energy is found in plains, where

values are generally three or four times lower than that at the coast.

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Multiblade Rotor: Rotors with more than two blades will produce high power.

Sail type blades:

It is of recent origin. The blade surface is made from cloth, nylon o r plastics

arranged as sail wings. There is also variation in the number of sails used.

The horizontal axis types generally have better performance than vertical types.

They are mainly used for power generation and pumping water. The biggest wind

mill erected for power generation is of 2500 kW capacity in U.S.A.

Advantages

1. The wind energy is a renewable source of energy. It is free and inexhaustible. 2. The power requirements for irrigation, lighting and small industrial units can be

fulfilled with the use of wind energy. Power generation on large scale using wind

energy is not yet so successful, but the small wind mills will play a vital role in the present condition of power shortage.

3. It does not need transportation. 4. Like all forms of solar energy, wind power systems are non-polluting. Disadvantages

1. Wind velocity is fluctuating which makes the complications in designing a wind

power plant.

2. Some form of storage of wind energy is essential to maintain a constant supply of power.

3. The wind is a very hazardous, treacherous and unpredictable source of energy. Blowing

in strong gusts from varying directions causing hurricanes the wind may smash the

whole plant within no time. To avoid this, special and costly designs and contro ls

are always required.

4. It is, considered suitable and economical to generate power on a small scale of the order of 2 MW.

5. Power production cost with the present technology available may not compete with

the conventional power generating systems. This is because, 1000s of units are

required to provide the power output of one fossil-fuelled plant. 6. Wind energy systems are noisy in operation. A large unit can be heard many

kilometers a away

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Expected Learning outcome:

To know how solar energy and wind energy are used to harness energy and power plants are

built based on these enrgy and constraints face in the process.

Questions. 1.Give the applications of solar energy? 2.What is butane boiler?

3.Name the two types of solar collectors? 4.What are the materials used to absorb energy from the radiation in the solar collectors? 5.What are the two types of wind mills according to the axis? 6 Describe the principle of wind mill?

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STUDY MATERIAL





Title: < NON-CONVENTIONAL POWER GENERATING SYSTEMS USING RENEWABLE SOURCES OF ENERGY-2>


<To gain knowledge about tidal and geothermal power plant.>

Methodology:

0 – 10Minutes : Introduction to tidal power plants and geothermal power plants

11 – 30 Minutes : Tidal power pant and its operation

31 – 45 Minutes : Geothermal powerplant and its working


Brief Content:

Introduction to tidal power plants and geothermal power plants

: Tidal power pant and its operation

Geothermal powerplant and its working

1.7.1 TIDAL POWER GENERATION

Principle

Tide or wave is periodic rise and fall of water level of the sea. Tides occur due to the

attraction of sea water by the moon. Tides contain large amount of potential energy which

is used for power generation. When the water is above the mean sea level, it is called flood

tide. When the water level is below the mean level it is called ebb tide.

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Working

The ocean tides rise and fall and water can be stored during the rise period and it can be

discharged during fall. A dam is constructed separating the tidal basin from the sea and

a difference in water level is obtained between the basin and sea.

High tide:

During high tide period, water flows from the sea into the tidal basin through the water

turbine. The height of tide is above that of tidal basin. Hence the turbine unit operates and

generates power, as it is directly coupled to a generator

Low tide:

During low tide period, water flows from tidal basin to sea, as the water level in the basin

is more than that of the tide in the sea. During this period also, the flowing water rotates the

turbine and generates power.

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The generation of power stops only when the sea level and the tidal basin level are equal.

For the generation of power economically using this source of energy requires some

minimum tide height and suitable site. Kislaya power plant of 250 MW capacity in Russia

and Rance power plant in France are the only examples of this type of power plant.

Advantages of tidal power plants

1. It is free from pollution as it does not use any fuel. 2. It is superior to hydro-power plant as it is totally independent of rain. 3. It improves the possibility of fish farming in the tidal basins and it can provide

recreational facilities to visitors and holiday makers.

Disadvantages

1. Tidal power plants can be developed only if natural sites are available on the bay. 2. As the sites are available on the bays which are always far' away from load centres,

the power generated has to be transmitted to long distances. This increases the .transmission cost and transmission losses.

3. The supply of power is not continuous as it depends upon the timing of tides. 4. The navigation is obstructed. 5. Utilization of tidal energy on small scale is not economical.

1.7.2 GEO-THERMAL POWER PLANT

It is also a thermal power plant, but the steam required for power generation is available

naturally in some part of the earth below the earth surface. According to various theories

earth has a molten core. The fact that volcanic action takes place in many places on the

surface of earth supports these theories

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Working

Steam well:

Pipes are embedded at places of fresh volcanic action called steam wells, where the

molten internal mass of earth vents to the atmosphere with very high temperatures. By

sending water through embedded pipes, steam is raised from the underground steam

storage wells to the ground level.

Separator:

The steam is then passed through the separator where most of the dirt and sand

carried by the steam are removed.

Turbine:

The steam from the separator is passed through steam drum and is used to run the

turbine which in turn drives the generator. The exhaust steam from the turbine is

condensed. The condensate is pumped into the earth to absorb the ground heat again and

to get converted into steam.

Location of the plant, installation of equipment like control unit etc., within the source of heat

and the cost of drilling deep wells as deep as 15,000 metres are some of the difficulties com-

monly encountered.

Expected Learning outcome

To know how tidal energy and geothermal energy are used to harness energy and power plants are

built based on these energy and constraints faced in the process with their advantages and

limitations.

Questions.

1. Describe the main principle of tidal power plant?

2.. What is meant by flood tide? 3.. Name the few factors considered while installing power plant? 4.. Give the functions of steam separator using in a geo thermal power plant? 5.. Write two advantages and disadvantages of tidal power plants? 6. Explain in detail any three non conventional energy sources systems layout with

neat sketch.

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STUDY MATERIAL





Title: < INTERNAL COMBUSTION ENGINES –INTRODUCTION AND

CONSTRUCTION>


<To gain knowledge about internal combustion engine and their parts.>

Methodology:

0 – 10Minutes : Introduction to internal combustion engines

11 – 30 Minutes : Engine construction and its parts

31 – 40 Minutes : Discussion on Advantages and limitations of IC engines

41 – 45 Minutes : Classifications of internal combustion engines


Brief Content:

Introduction to internal combustion engines

Advantages and limitations of IC engines Frictional effects

Classifications of internal combustion engines

Detailed Content:

2.1.1.Engine construction:

Introduction

Internal-combustion engine, one in which combustion of the fuel takes place in a confined

space, producing expanding gases that are used directly to provide mechanical power. Such engines

are classified as reciprocating or rotary, spark ignition or compression ignition, and two-stroke or

four-stroke; the most familiar combination, used from automobiles to lawn mowers, is the

reciprocating, spark- ignited, four-stroke gasoline engine. Other types of internal-combustion

engines include the reaction engine (see jet propulsion, rocket), and the gas turbine. Engines are

http://www.infoplease.com/encyclopedia/science/jet-propulsion.html

http://www.infoplease.com/encyclopedia/science/jet-propulsion.html

http://www.infoplease.com/encyclopedia/science/turbine.html

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rated by their maximum horsepower, which is usually reached a little below the speed at which

undue mechanical stresses are developed.

2.1.2 Components of IC engine:

Connecting rod: Linkage connecting piston with rotating crankshaft usually made of steel alloy forging or aluminum. Connecting rod bearing: Bearing where connecting rod fastens to crankshaft. Cooling fins: Metal fins on the outside surfaces of cylinders and head of an air cooled engine. These extended surfaces cool the cylinders by conduction and convection.

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Piston: The cylindrically shaped mass that reciprocates back and forth in the cylinder transmitting

the pressure forces in the combustion chamber rotating the crankshaft. The top of the piston is

called crown and the sides are called skirt. The face on the crown makes up one wall of the

combustion chamber and may be a flat or highly contoured surface. Some pistons contain an

indented bowl in the crown which makes up a large percent of clearance volume. Pistons are made

of cast iron aluminum or steel. Iron and steel pistons can have sharper corners because of their

higher strength. They also have lower thermal expansion which allows for tighter tolerances and

less crevice volume. Aluminum pistons are lighter and have less mass inertia. Sometimes synthetic

or composite materials are used for the body of the piston, with only the crown made of metal.

Some pistons have a ceramic coating on the face.

Piston rings: Metal rings that fit into circumferential groups around the piston and form a sliding

surface against the cylinder walls. Near the top of the piston are usually two or more compression

rings made with highly polished surfaces. The purpose of the rings is to form a seal between the

piston and cylinder walls and to restrict the high pressure gases in the combustion chamber from

leaking pass the piston into the crank cars (Blow by). Below the compression rings on the piston is

at least one oil ring, which assists in lubricating the cylinder walls and scrapes away excess oil to

reduce oil consumption.

Push rods: Mechanical linkage between the camshaft and valves on over head valves engines with

the camshaft in a crankcase.

Crankcase: Part of the engine block surrounding the rotating crankshaft> in many engines the oil pan makes up part of the crankcase housing. In some high performance engines the crankcase is designed with windows between the piston bays to allow free airflow between bays. This is to reduce air pressure build up on the backside of the pistons during power and intake strokes. Crankshaft: Rotating shaft through which engine work output is supplied to external systems. The

crankshaft is connected to the engine block with the main bearings. It is rotated by the reciprocating pistons through connecting rods connected to the crankshaft, offset from the axis of rotation. This

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offset is sometimes called Crank throw or crank radius. Most crankshafts are made of forged steel, while some are made of cast iron. Cylinders: The circular cylinders in the engine block in which the pistons reciprocate back and

forth. The walls of the cylinder have highly polished hard surfaces. Cylinders may be machined directly in the engine block or hard metal (drawn steel) sleeve may be pressed into the softer metal

block. Sleeves may be dry sleeves, which do not contact the liquid in the water jacket or wet

sleeves which form part of the water jacket. In a few engines, the cylinder valves are given knurled surface to help hold a lubricant film on the walls. In some very rare cases, the cross-section of the

cylinder is not round. Block: Body of engine containing the cylinders made of cast iron or aluminum. In many older engines the valves and the valve ports were contained in the block. The block of water cooled engines includes a water jacket cast around the cylinders. On air cooled engines the exterior surface of the block has cooling fins. Camshaft: Rotating shaft used to push open valves at the proper time in the engine cycle either directly or through mechanical or hydraulic linkage (push rods, rocker arms, and tappets). Most

modern automobile engines have one or more camshafts mounted in the engine head (Overhead cam). Older engines had camshafts in the crank case. Crankshafts are generally made of forget steel

or cast iron and driven off the crankshaft by means of a belt or chain (Timing chain). To reduce

weight, some cams are made from a hollow shaft with the cam lobes press-fit on. In four stroke cycle engines the camshaft rotates at half engine speed. Carburetor: Venturi flow device that meters the proper amount of fuel into the air flow by means

of pressure differential. For many decades it was the basic fuel metering system on all automobile (and other) engines. It is still used on low cost small engines like lawn mowers but is uncommon on new automobiles.

ADVANTAGES OF INTERNAL COMBUSTION ENGINES 1. Greater mechanical simplicity.

2. Higher power output per unit weight because of absence of auxiliary units like boiler , condenser and feed pump

3. Low initial cost 4. Higher brake thermal efficiency as only a small fraction of heat energy of the fuel is dissipated to cooling system

5. These units are compact and requires less space 6. Easy starting from cold conditions

DISADVANTAGES OF INTERNAL COMBUSTION ENGINES 1. I C engines cannot use solid fuels which are cheaper. Only liquid or gaseous fuel of given

specification can be efficiently used. These fuels are relatively more expensive. 2. I C engines have reciprocating parts and hence balancing of them is problem and they are also susceptible to mechanical vibrations.

2.1.3 CLASSIFICATION OF INTERNAL COMBUSTION ENGINES:

There are different types of IC engines that can be classified on the following

basis. 1. According to thermodynamic cycle

i) Otto cycle engine or Constant volume heat supplied cycle. ii) Diesel cycle engine or Constant pressure heat supplied cycle iii) Dual-combustion cycle engine

2. According to the fuel used:

i) Petrol engine ii) Diesel engine iii) Gas engine

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2. According to the cycle of operation:

i) Two stroke cycle engine ii) Four stroke cycle

engine 4. According to the method of ignition:

i) Spark ignition (S.I) engine ii) Compression ignition (C I )

engine 5. According to the number of cylinders. i) Single cylinder engine ii) Multi cylinder engine

6. According to the arrangement of cylinder:

I) Horizontal engine ii) Vertical engine iii) V-engine

v) In-line engine vi) Radial engine, etc.

7. According to the method of cooling the cylinder:

I) Air cooled engine ii) Water cooled engine

8. According to their applications:

i) Stationary engine ii) Automobile engine iii) Aero engine

iv) Locomotive engine v) Marine engine, etc.


Knowledge principle,construction,working,merits and limitations of diesel power

plant,hydroelectric power plant and nuclear power plants.

Questions 1) List out the major parts of an IC engine.

2)What is the function of crankshaft?

3)What is the function of connecting rod?

4)What is the cylinder block? 5)What is a crankcase? 6)What are the materials used for cylinder

block? 7)What is oil pan? Where it is?

8) Classify the IC engine types.

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STUDY MATERIAL


BE (All branches) I / I& II EBU12DT095 2



Title: < INTERNAL COMBUSTION ENGINES –FOUR STROKE AND TWO STROKE

PETROL AND DIESL ENGINES>


<To gain knowledge about two stroke and four stroke engines.>

Methodology:

0 – 5Minutes : Introduction to four stroke and two stroke petrol and diesel engines

5 – 20 Minutes : Working of Four stroke Spark Ignition(SI) and Compression

ignition(CI) engines

21 – 35 Minutes Working of Four stroke SI and CI engines

35 – 40 Minutes Discussion on comparison of two stroke and four stroke engines

40 – 45 Minutes Discussion on comparison of SI and CI engines


Brief Content:

Working of Four stroke Spark Ignition(SI) and Compression ignition(CI) engines

Comparison of two stroke and four stroke engines

Comparison of SI and CI engines

Detailed Content

2.2.1 Four Stroke Petrol Engine (Four Stroke Spark Ignition Engine— S.I.Engine):

Suction Stroke : During suction stroke, the piston is moved from the top dead centre to the bottom

dead centre by the crank shaft. The crank shaft is revolved either by the momentum of the flywheel

or by the electric starting motor. The inlet valve remains open and the exhaust valve is closed

during this stroke. The proportionate air-petrol mixture is sucked into the cylinder due to the

downward movement of the piston. This operation is represented by the line AB on the P-V

diagram.

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Compression Stroke: During compression stroke, the piston moves from bottom dead centre to the

top dead centre, thus compressing air petrol mixture. Due to compression, the pressure and

temperature are increased and is shown by the line BC on the P- V diagram. Just before the end of

this stroke the spark - plug initiates a spark, which ignites the mixture and combustion takes place at

constant volume as shown by the line CD. Both the inlet and exhaust valves remain closed during

this stroke. Working Stroke: The expansion of hot gases exerts a pressure on the piston. Due to this pressure,

the piston moves from top dead centre to bottom dead centre and thus the work is obtained in this

stroke. Both the inlet and exhaust valves remain closed during this stroke. The expansion of the gas

is shown by the curve DE. Exhaust Stroke: During this stroke, the inlet valve remains closed and the exhaust valve opens.

The greater part of the burnt gases escapes because of their own e xpansion. The drop in pressure at

constant volume is represented by the line EB. The piston moves from bottom dead centre to top

dead centre and pushes the remaining gases to the atmosphere. When the piston reaches the top

dead centre the exhaust valve closes and cycle is completed. This stroke is represented by the line

BA on the P- V diagram. The operations are repeated over and over again in running the engine.

Thus a four stroke engine completes one working cycle, during this the crank rotate by two

revolutions.

2.2.2 Four Stroke Diesel Engine (Four Stroke Compression Ignition Engine — C.I.Engine)

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Suction Stroke: During suction stroke, the piston is moved from the top dead centre to the bottom

dead centre by the crankshaft. The crankshaft is revolved either by the momentum of the flywheel

or by the power generated by the electric starting motor. The inlet valve remains open and the

exhaust valve is closed during this stroke. The air is sucked into the cylinder due to the downward

movement of the piston. The line AB on the P- V diagram represents this operation.

Compression Stroke: The air drawn at the atmospheric pressure during suction stroke is

compressed to high pressure and temperature as piston moves from the bottom dead centre to top

dead centre. This operation is represented by the curve BC on the P- V diagram. Just before the end of this stroke, a metered quantity of fuel is injected into the hot compressed air in the form of

finesprays by means of fuel injector. The fuel starts burning at constant pressure shown by the line CD. At point D, fuel supply is cut off, Both the inlet and exhaust valves remain closed during this

stroke. Working Stroke: The expansion of gases due to the heat of combustion exerts a pressure on the

piston. Under this impulse, the piston moves from top dead centre to the bottom dead centre and thus work is obtained in this stroke. Both the inlet and exhaust valves remain closed during this stroke. The expansion of the gas is shown by the curve DE. Exhaust Stroke: During this stroke, the inlet valve remains closed and the exhaust valve opens.

The greater part of the burnt gases escapes because of their own expansion. The vertical line EB

represents the drop in pressure at constant volume. The piston moves from bottom dead centre to

top dead centre and pushes the remaining gases to the atmosphere. When the piston reaches the top

dead centre the exhaust valve closes and the cycle is completed. The line BA on the F- V diagram

represents this stroke.

2.2.3 TWO STROKE CYCLE ENGINE: In two stroke cycle engines, the suction and exhaust strokes are eliminated. There are only

two remaining strokes i.e., the compression stroke and power stroke and these are usually called

upward stroke and downward stroke respectively. Also, instead of valves, there are inlet and

exhaust ports in two stroke cycle engines. The burnt exhaust gases are forced out through the

exhaust port by a fresh charge which enters the cylinder nearly at the end of the working stroke

through the inlet port. The process of removing burnt exhaust gases from the engine cylinder is

known as scavenging.

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Two Stroke Cycle Petrol Engine: The principle of two-stroke cycle petrol engine is shown in Figure 7. Its two strokes are described

as follows:

Upward Stroke: During the upward stroke, the piston moves from bottom dead centre to top dead

centre, compressing the air-petrol mixture in the cylinder. The cylinder is connected to a closed

crank chamber. Due to upward movement of the piston, a partial vacuum is created in the

crankcase, and a new charge is drawn into the crank case through the uncovered inlet port. The exhaust port and transfer port are covered when the piston is at the top dead centre position as

shown in Figure (b). The compressed charge is ignited in the combustion chamber by a spark provided by the spark plug. Downward Stroke: As soon as the charge is ignited, the hot gases force the piston to move

downwards, rotating the crankshaft, thus doing the useful work. During this stroke the inlet port is

covered by the piston and the new charge is compressed in the crank case as shown in the Figure (c)

Further downward movement of the piston uncovers first the exhaust port and then the transfer port

as shown in Figure (d). The burnt gases escape through the exhaust port. As soon as the transfer

port opens, the compressed charge from the crankcase flows into the cylinder. The charge is

deflected upwards by the hump provided on the head of the piston and pushes out most of the

exhaust gases.

It may be noted that the incoming air-petrol mixture helps the removal of burnt gases from the

engine cylinder. If in case these exhaust gases do not leave the cylinder, the fresh charge gets diluted and efficiency of the engine will decrease. The cycle of events is then repeated.

Two Stroke Diesel Engines:

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Upward Stroke: During the upward stroke, the piston moves from bottom dead centre to top dead

centre, compressing the air in the cylinder. The cylinder is connected to a closed crank chamber.

Due to upward movement of the piston, a partial vacuum is created in the crankcase, and a new

charge is drawn into the crank case through the uncovered inlet port. The exhaust port and transfer

port are covered when the piston is at the top dead centre position as shown in Figure. The

compressed charge is ignited in the combustion chamber by injecting the fuel. Downward Stroke: As soon as the charge is ignited, the hot gases force the piston to move

downwards, rotating the crankshaft, thus doing the useful work. During this stroke the inlet port is

covered by the piston and the new charge is compressed in the crank case as shown in the Figure.

Further downward movement of the piston uncovers first the exhaust port and then the transfer port

as shown in Figure. The burnt gases escape through the exhaust port. As soon as the transfer port

opens, the compressed charge from the crankcase flows into the cylinder. The charge is deflected

upwards by the hump provided on the head of the piston and pushes out most of the exhaust gases.

It may be noted that the incoming air helps the removal of burnt gases from the engine cylinder. If

in case these exhaust gases do not leave the cylinder, the fresh charge gets diluted and efficiency of

the engine will decrease. The cycle of events is then repeated.

2.2.4 Comparison of 4S and 2S engines:

.

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Comparison of SI and CI stroke engines:


To understand the detailed working of four stroke engines and two stroke engines with spark

ignition and compression igntion.and alson know the distinction between these engines.

Questions 1. Compare two stroke and Four Stroke petrol engine. 2.List the demerits of Two Stroke engine 3. With neat sketches explain the functions of an IC engine process.

4. Explain the working principle of Two Stroke petrol engine with neat sketches. 5. Explain the working principle of a ―FOUR STOKE‖ engine with neat sketches

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STUDY MATERIAL





Title: < INTERNAL COMBUSTION ENGINES –FUEL INECTION SYSTEMS IN

PETROL AND DIESEL ENGINES>


<To gain knowledge about fuel injection system of petrol and diesel engines.

Methodology:

0 –5Minute Introduction to various systems of fuel injection

6 – 15 Minutes Carburetor and its working:

16 – 30 Minutes Various fuel ignition systems for petrol engines.

30-45 Minutes Fuel injecting parts of Diesel engine:

46– 50 Minutes Attendance :

Brief Content:

Description and functioning of Carburettor used in petrol

engines. :Fuel injection systems for petrol engines

Fuel injecting parts of diesel engine

2.3.1 FUEL INJECTION SYSTEM OF PETROL ENGINES

Simple carburetor

The function of a carburetor is to vaporize the petro l (gasoline) by means of engine suction

and to supply the required air and fuel (petrol) mixture to the engine cylinder. During the suction

stroke, air flows from atmosphere into the cylinder. As the air passes through the venturi, velocity

of air increases and its pressure falls below the atmosphere. The pressure at the nozzle tip is also

below the atmospheric pressure. The pressure on the fuel surface of the fuel tank is atmospheric.

Due to which a pressure difference is created, which causes the flow of fuel through the fuel jet into

the air stream. As the fuel and air pass ahead of the venturi, the fuel gets vaporized and required

uniform mixture is supplied to the engine.

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The main parts of a simple carburetor are:

Float chamber: The level of fuel in the float chamber is maintained slightly below the tip of the

nozzle. If the level of petrol is above then the petrol will run from the nozzle and drip from the

carburetor. If the petrol level is kept low than the tip of the nozzle then part of pressure head is lost

in lifting the petrol up to the tip of nozzle. Generally it is kept at 5mm from the level of petrol in the

float chamber. The level of the fuel is kept constant with the help of float and needle valve. The

needle valve closes the inlet supply from main tank if the level rises above the required level. If the

level of fuel decreases then the needle valve opens the supply. Generally the fuel level is kept 5mm

below the nozzle tip. Venturi: When the mixture passes through the narrowest section its velocity increases and pressure

falls below the atmospheric. As it passes through the divergent section, pressure increases again. Throttle valve: It controls the quantity of air and fuel mixture supplied to the engine through intake

manifold and also the head under which the fuel flows. Choke: It provides an extra rich mixture during to the engine starting and in cold weather to warm

up the engine. The choke valve is nearly closed during clod starting and warming. It creates a high vacuum near the fuel jet which causes flow of more fuel from the jet.

2.3.2 IGNITION SYSTEMS

Introduction:

We know that in case of Internal Combustion (IC) engines, combustion of air and fuel takes place

inside the engine cylinder and the products of combustion expand to produce reciprocating motion of the piston. This reciprocating motion of the piston is in turn converted into rotary motion of the

crank shaft through connecting rod and crank. This rotary motion of the crank shaft is in turn used to drive the generators for generating power. We also know that there are 4-cycles of operations

viz.: suction; compression; power generation and exhaust. These operations are performed either

during the 2-strokes of piston or during 4-strokes of the piston and accordingly they are called as 2-stroke cycle engines and 4-stroke cycle engines.

In case of petrol engines during suction operation, charge of air and petrol fuel will be taken in. During compression this charge is compressed by the upward moving piston. And just before the

end of compression, the charge of air and petrol fuel will be ignited by means of the spark produced

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by means of for spark plug. And the ignition system does the function of producing the spark in case of spark ignition engines.

IGNITION SYSTEM TYPES

Basically Convectional Ignition systems are of 3 types :

(a) Battery or Coil Ignition System, (b) Magneto Ignition System, and (c) Electronic ignition system.

1. Battery or Coil Ignition System:

Figure shows line diagram of battery ignition system for a 4-cylinder petrol engine. It mainly

consists of a 6 or 12 volt battery, ammeter, ignition switch, auto-transformer (step up transformer),

contact breaker, capacitor, distributor rotor, distributor contact points, spark plugs, etc. Note that the

Figure shows the ignition system for 4-cylinder petrol engine, here there are 4-spark plugs and

contact breaker cam has 4-corners. (If it is for 6-cylinder engine it will have 6-spark plugs and

contact breaker cam will be a perfect hexagon).

The ignition system is divided into 2-circuits:

(i) Primary Circuit : It consists of 6 or 12 V battery, ammeter, ignition switch, primary winding it has 200-300 turns of 20 SWG (Sharps Wire Gauge) gauge wire, contact breaker, capacitor.

(ii) Secondary Circuit : It consists of secondary winding. Secondary winding consists of about 21000 turns of 40 (S WG) gauge wire. Bottom end of which is connected to bottom end of primary and top end of secondary winding is connected to centre of distributor rotor. Distributor rotors rotate and make contacts with contact points and are connected to spark plugs which are fitted in cylinder heads (engine earth). (iii) Working : When the ignition switch is closed and engine in cranked, as soon as the contact

breaker closes, a low voltage current will flow through the primary winding. It is also to be noted

that the contact beaker cam opens and closes the circuit 4-times (for 4 cylinders) in one revolution.

When the contact breaker opens the contact, the magnetic field begins to collapse. Because of this

collapsing magnetic field, current will be induced in the secondary winding. And because of more

turns (@ 21000 turns) of secondary, voltage goes unto 28000-30000 volts. This high voltage

current is brought to centre of the distributor rotor. Distributor rotor rotates and supplies this high

voltage current to proper stark plug depending upon the engine firing order. When the high voltage

current jumps the spark plug gap, it produces the spark and the charge is ignited-combustion starts-

products of combustion expand and produce power.

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2. Magneto Ignition System:

In this case magneto will produce and supply the required current to the primary winding. In this case as shown, we can have rotating magneto with fixed coil or rotating coil with fixed magneto for producing and supplying current to primary, remaining arrangement is same as that of a battery ignition system.

When the contact breaker points are closed: The current flows in the primary circuit.

This produces a magnetic field in the primary circuit.

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When the primary circuit is at highest peak,the contact breake po ints will be opened by

cam.

When the contact breaker points are opened:

Collapse in the magnetic field in the primary circuit induces a high voltage in the secondary

winding.

This is distributed by the rotor to the spark plug.

This voltage then tries to cross the spark plug and a spark is generated.

3. Electronic Ignition System:

It consists of a battery,ignition switch,electronic control unit,magnetic pick up,reluctor or

armature,ignition coil,distributor,spark plug.Magnetic pick up is used instead of contac t breaker

points,and a cam is replaced by a reluctor or armature. Magnetic pick up consists of a sensor coil

through which the flux is generated by a permanent magnet. Armature modulates the flux density in

the coil.

When the ignition switch is closed,the armature rotates which makes the teeth of the reluctor cone come closer to the permanent magnet.

This reduces the air gap between the reluctor tooth and the sensor coil.

Thus an electric pulse is generated,which triggers the E.C.U. which stops the battery current to the ignition coil.

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Thus magnetic field collapses and high voltage is generated in the secondary coil,which is

distributed to the spark plug by the rotor.

2.3.3 DIESEL ENGINE FUEL SUPPLY PARTS

FUEL INJECTIOR

Advantages : precise and variable fuel metering, better fuel efficiency and better emissions.

Disadvantages : Fairly complex engineering that isn't very user-friendly. Binary on/off

functionality at low throttles, which is especially noticable on motorbikes where the throttle

becomes 'snatchy' and it becomes hard to ride smoothly at low speed.

HOW IT WORKS.

Compared to carburettors, fuel injectors themselves are incredibly simple. They are basically

electro-mechanically operated needle valves. The image on the right shows a cutaway of a

representative fuel injector. When a current is passed through the injector electromagnetic coil, the

valve opens and the fuel pressure forces petrol through the spray tip and out of the diffuser nozzle,

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atomising it as it does so. When current is removed, the combination of a spring and fuel back-

pressure causes the needle valve to close. This gives an audible 'tick' noise when it happens, which

is why even a quiet fuel- injected engine has a soft but rapid tick-tick-tick-tick noise as the injectors

fire. This on-off cycle time is known as the pulse width and varying the pulse width determines

how much fuel can flow through the injectors. When you ask for more throttle either via the

accelerator pedal or twist- grip (on a motorbike) you're opening a butterfly valve similar to the one

in a carburettor. This lets more air into the intake system and the position of the throttle is measured

with a potentiometer. The engine control unit (ECU) gets a reading from this potentiometer and

"sees" that you've opened the throttle. In response the ECU increases the injector pulse width to

allow more fuel to be sprayed by the injectors. Downwind of the throttle body is a mass airflow

sensor. This is normally a heated wire. The more air that flows past it, the quicker it disappates heat

and the more current it needs to remain warm. The ECU can continually measure this current to

determine if the fuel-air mix is correct and it can adjust the fuel flow through the injectors

accordingly. On top of this, the ECU also looks at data coming from the oxygen (lambda) sensors in

the exhaust. These tell the ECU how much oxygen is in the exhaust so it can automatically adjust

for rich- or lean-running.

FUEL PUMP

Mechanical Pumps

Mechanical pumps are usually found on carbureted engines or on engines that utilize a mechanical

fuel injection system.

Mechanical fuel pumps on carbureted engines are usually mounted on the side of the engine block or cylinder

head and operated by an eccentric on the engine's camshaft. The rocker arm of the pump rests against the

camshaft eccentric, and as the camshaft rotates, it actuates the rocker arm. Some engines use a pushrod between

the rocker arm and camshaft eccentric. Inside the fuel pump, the rocker arm is connected to a flexible diaphragm.

A spring, mounted underneath, maintains pressure on the diaphragm. As the rocker arm is actuated, it pulls the

diaphragm down and then releases it. Once the diaphragm is released, the spring pushes it back up. This continual

diaphragm motion causes a partial vacuum and pressure in the space above the diaphragm. The vacuum draws the

fuel from the tank and the pressure pushes it toward the carburetor or injection pump. A check valve is used in the

pump to prevent fuel from being pumped back into the tank.

Certain mechanical fuel injection systems also utilize a mechanical fuel pump, typically some diesel engines and

early gasoline fuel injection systems. Many of them use a fuel pump essentially identical to the carbureted fuel

system's. Some, however, use a vane type fuel pump mounted directly to the injection

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pump/fuel distributor assembly. The injection pump/fuel distributor assembly is driven by the timing

belt, chain or gears which in turn drives the fuel pump. The vanes draw the fuel in through the inlet

port then squeeze the fuel into a tight passage. The fuel then exits pressurized through the outlet port.


To know about various parts involved in fuel injection and ignition in petrol and diesel engines.

Questions

1) What is meant by carburetion? 2) What are the functions of carburetor? 3) Define ignition system. 4) Write the functions of control breaker point. 5)Describe the various fuel supply system automotive petrol engines with neat sketches 6) Sketch and explain the construction and operations of a simple carburetor. 14) Discuss in detail

the function of the fuel supply system in an automotive diesel engine. State also the names of various components to perform these functions. 7)Draw diagrams showing the layout of various types of fuel supply system for

diesel engine and discuss them extensively.

8) Explain construction and working of fuel pump with neat sketches. 9) Explain the construction and working of fuel injector.

10) Explain the working principle of coil ignition system in SI engine with neat sketch

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STUDY MATERIAL





Title: < INTERNAL COMBUSTION ENGINES –COOLING SYSTEM AND

LUBRICATION SYSTEM>


<To gain knowledge about various cooling system aan llubricating system used in internal

combustion engines..>

Methodology:

0 – 10Minutes : Necessity and requirements for coling system in IC engines.

11 – 25 Minutes : Types of cooling system , their description and working

26 – 30 Minutes : Purpose of lubrication systems and types of lubricants

31 – 45 Minutes : Types of lubrication system and their description and working


Brief Content:

Necessity and requirements for coling system in IC engines

Types of cooling system , their description and working

Purpose of lubrication systems and types of lubricants

Types of lubrication system and their description and working

2.4.1 COOLING SYSTEM

A system, which controls the engine temperature, is known as a cooling system.

NECESSITY OF COOLING SYSTEM

The cooling system is provided in the IC engine for the following reasons: The temperature of the burning gases in the engine cylinder reaches up to 1500 to 2000°C,

which is above the melting point of the material of the cylinder body and head of the engine.

(Platinum, a metal which has one of the highest melting points, melts at 1750 °C, iron at 1530°C

and aluminium at 657°C.) Therefore, if the heat is not dissipated, it would result in the failure of the

cylinder material.

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• Due to very high temperatures, the film of the lubricating oil will get oxidized, thus producing carbon deposits on the surface. This will result in piston seizure. • Due to overheating, large temperature differences may lead to a distortion of the engine components due to the thermal stresses set up. This makes it necessary for, the temperature variation to be kept to a minimum. • Higher temperatures also lower the volumetric efficiency of the engine.

REQUIREMENTS OF EFFICIENT COOLING SYSTEM

The two main requirements of an efficient cooling system are: 1. It must be capable of removing only about 30% of the heat generated in the combustion chamber. Too much removal of heat lowers the thermal efficiency of the engine. 2. It should remove heat at a fast rate when the engine is hot. During the starting of the engine, the cooling should be very slow so that the different working parts reach their operating temperatures in a short time.

2.4.2 TYPES OF COOLING SYSTEM

There are two types of cooling systems: (i) Air cooling system and

(ii) Water-cooling system.

AIR COOLING SYSTEM

In this type of cooling system, the heat, which is conducted to the outer parts of the engine, is radiated and conducted away by the stream of air, which is obtained from the atmosphere. In order to have efficient cooling by means of air, providing fins around the cylinder and cylinder head increases the contact area. The fins are metallic ridges, which are formed during the casting of the cylinder and cylinder head The amount of heat carried off by the air-cooling depends upon the following factors: (i) The total area of the fin surfaces, (ii) The velocity and amount of the cooling air and (iii) The temperature of the fins and of the cooling air. Air-cooling is mostly tractors of less horsepower, motorcycles, scoote rs, small cars and small

aircraft engines where the forward motion of the machine gives good velocity to cool the engine.

Air-cooling is also provided in some small industrial engines. In this system, individual cylinders

are generally employed to provide ample cooling area by providing fins. A blower is used to

provide air.

Advantages of Air Cooled Engines

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Air cooled engines have the following advantages:

1. Its design of air-cooled engine is simple. 2. It is lighter in weight than water-cooled engines due to the absence of water jackets, radiator, circulating pump and the weight of the cooling water. 3. It is cheaper to manufacture. 4. It needs less care and maintenance. 5. This system of cooling is particularly advantageous where there are extreme climatic conditions in the arctic or where there is scarcity of water as in deserts.

6. No risk of damage from frost, such as cracking of cylinder jackets or radiator water tubes.

WATER COOLING SYSTEM

It serves two purposes in the working of an engine:

a) It takes away the excessive heat generated in the engine and saves it from ove rheating. b)

It keeps the engine at working temperature for efficient and economical working.

This cooling system has four types of systems: (i) Direct or non-return system, (ii) Thermo-Syphone system,

(iii) Hopper system and (iv) Pump/forced circulation system. Though the present tractor has a forced circulation system, it is still worthwhile to get acquainted

with the other three systems.

1. Non-Return Water Cooling System This is suitable for large installations and where plenty of water is available. The water from a

storage tank is directly supplied to the engine cylinder. The hot water is not cooled for reuse but simply

discharges. The

low H.P. engine, coupled with the irrigation pump is an example.

2. Thermo-Syphone Water Cooling System:

This system works on the principle that hot water being lighter rises up and the cold water

being heavier goes down. In this system the radiator is placed at a higher level than the engine for

the easy flow of water towards the engine. Heat is conducted to the water jacke ts from where it is

taken away due to convection by the circulating water. As the water jacket becomes hot, it rises to

the top of the radiator. Cold water from the radiator takes the place of the rising hot water and in

this way a circulation of water is set up m the system. This helps in keeping the engine at working

temperature. Disadvantages of Thermo-Syphone System:

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1 Rate of circulation is too slow.

2. Circulation commences only when there is a marked difference in temperature. 3. Circulation stops as the level of water falls below the top of the delivery pipe of the radiator. For these reasons this system has become obsolete and is no more in use.

3. Hopper Water Cooling System This also works on the same principle as the thermo-syphone system. In this there is a

hopper on a jacket containing water, which surrounds the engine cylinder. In this system, as soon as water starts boiling, it is replaced by cold water. An engine fitted with this system cannot run for several hours without it being refilled with water.

4. Force Circulation Water Cooling System

This system is similar in construction to the thermo-syphone system except that it makes use of a centrifugal pump to circulate the water throughout the water jackets and radiator. The water

flows from the lower portion of the radiator to the water jacket of the engine through the centrifugal pump. After the circulation water comes back to the radiator, it loses its heat by the process of radiation. This system is employed in cars, trucks, tractors, etc.

Wate r circulation for four cylinders:

Parts of Liquid Cooling System

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The main parts in the water-cooling system are: (i) water pump, (ii) fan, (iii) radiator and pressure

cap, (iv) fan belt (v) water jacket, (vi) thermostat valve, (vii) temperature gauge and (viii) hose pipes.

Wate r Pump This is a centrifugal type pump. It is centrally mounted at the fro nt of the cylinder block and is

usually driven by means of a belt. This type of pump consists of the following parts: (i) body or

casing, (ii) impeller (rotor), (iii) shaft, (iv) bearings, or bush, (v) water pump seal and (vi) pulley.

The bottom of the radiator is connected to the suction side of the pump. The power is transmitted to

the pump spindle from a pulley mounted at the end of the crankshaft. Seals of various designs are

incorporated in the pump to prevent loss of coolant from the system.

Fan The fan is generally mounted on the water pump pulley; although on some engines it is attached

directly to the crankshaft. It serves two purposes in the cooling system of a engine. (a) It draws atmospheric air through the radiator and thus increases the efficiency of the radiator in

cooling hot water. (b) It throws fresh air over the outer surface of the engine, which takes away the heat conducted by the engine parts and thus increases the efficiency of the entire cooling system. Radiator

The purpose of the radiator is to cool down the water received from the engine.

2.4.3 LUBRICATION SYSTEM:

I. C. engine is made of many moving parts. Due to continuous movement of two metallic surfaces over each other, there is wearing moving parts, generation of heat and loss of power in the engine lubrication of moving parts is essential to prevent all these harmful effects. Purpose Of Lubrication: Lubrication produces the following effects: (a) Reducing friction effect (b) Cooling effect (c) Sealing effect and (d) Cleaning effect. (a) Reducing frictional effect: The primary purpose of the lubrication is to reduce friction and

wear between two rubbing surfaces. Two rubbing surfaces always produce friction. The continuous

friction produce heat which causes wearing of parts and loss of power. In order to avoid friction,

the contact of two sliding surfaces must be reduced as far a possible. This can be done by proper

lubrication only. Lubrication forms an oil film between two moving surfaces. Lubrication also

reduces noise produced by the movement of two metal surfaces over each other. (b) Cooling effect: The heat, generated by piston, cylinder, and bearings is removed by lubrication

to a great extent. Lubrication creates cooling effect on the engine parts. (c) Sealing effect: The lubricant enters into the gap between the cylinder liner, piston and piston rings. Thus, it prevents leakage of gases from the engine cylinder. (d) Cleaning effect: Lubrication keeps the engine clean by removing dirt or carbon from inside of the engine along with the oil. Lubrication theory: There are two theories in existence regarding the application of lubricants on a surface: (i) Fluid film theory and (ii) Boundary layer theory. (i) Fluid film theory: According to this theory, the lubricant is, supposed to act like mass of

globules, rolling in between two surfaces. It produces a rolling effect, which reduces friction. (ii) Boundary layer theory: According to this theory, the lubricant is soaked in rubbing surfaces and forms oily surface over it. Thus the sliding surfaces are kept apart from each other, thereby reducing friction.

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2.4.4 TYPES OF LUBRICANTS

Lubricants are obtained from animal fat, vegetables and minerals Lubricants made of animal fat, does not stand much heat. It becomes waxy and gummy which is not very suitable for

machines. Vegetable lubricants are obtained from seeds, fruits and plants. Cottonseed oil, olive oil, linseed oil and castor oil are used as lubricant in small Simple machines. Mineral lubricants are

most popular for engines and machines. It is obtained from crude petroleum found in nature. Petroleum lubricants are less expensive and suitable for internal combustion engines. A good

lubricant should have the following qualities: 1. It should have sufficient viscosity to keep the rubbing surfaces apart

2. It should remain stable under changing temperatures. 3. It should keep lubricated pans clean.

4. It should not corrode metallic surfaces.

2.4.5 ENGINE LUBRICATING SYSTEM The lubricating system of an engine is an arrangement of mechanism and devices which

maintains supply of lubricating oil to the rubbing surface of an engine at correct pressure and

temperature. The parts which require lubrication are: (i) cylinder walls and piston (ii) piston pin (iii)

crankshaft and connecting rod bearings (iv) camshaft bearings (v) valves and valve operating

mechanism (vi) cooling fan (vii) water pump and (viii) ignition mechanism. There are three common systems of lubrication used on stationary engines, tractor engines

and automobiles:

(i) Splash system (ii) Forced feed system and (iii) Combination of splash and forced feed

system.

SPLASH SYSTEM In this system, there is an oil trough, provided below the connecting rod. Oil is maintained

at a uniform level in the oil trough. This is obtained by maintaining a continuous flow of oil from

the oil sump or reservoir into a splash pan, which has a depression or a trough like arrangement

under each connecting rod. This pan receives its oil supply from the oil sump either by means of a

gear pump or by gravity. A dipper is provided at the lower end of the connecting rod. This dipper

dips into to oil trough and splashes oil out of the pan. The splashing action of oil maintains a fog or

mist of oil that drenches the inner parts of the engine such as bearings, cylinder walls, pistons,

piston pins, timing gears etc.

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This system is usually used on single cylinder engine with closes crankcase. For effective functioning of the engine, proper level of oil maintained in the oil pan.

Lubrication depends largely upon the size of oil holes and clearances. This system is very

effective if the oil is clean and undiluted. Its disadvantages are that lubrication is not very uniform

and when the rings are worn, the oil passes the piston into combustion chamber, causing carbon

deposition, blue smoke and spoiling the plugs. There is every possibility that oil may become very

thin through crankcase dilution. The worn metal, dust and carbon may be collected in the oil

chamber and be carried to different parts of the engine, causing wear and tear.

Pressure lubrication system:

In this system, the oil is pumped directly lo the crankshaft, connecting rod, piston pin, timing gears

and camshaft of the engine through suitable paths of oil. Usually the oil first enters the main

gallery, which may be a pipe or a channel in the crankcase casting. From this pipe, it goes to each

of the main bearings through holes. From main bearings, it goes to big end bearings of connecting

rod through drilled holes in the crankshaft. From there, it goes to lubricate the walls, pistons and

rings. There is separate oil gallery to lubricate timing gears. Lubricating oil pump is a positive

displacement pump, usually gear type or vane' type. The oil also goes to valve stem and rocker arm

shaft under pressure through an oil gallery.

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The excess oil comes back from the cylinder head to the crankcase. The pump discharges oil into

oil pipes, oil galleries or ducts, leading different parts of the engine. This system is commonly used

on high speed multi-cylinder engine in tractors, trucks and automobiles.

Dry Sump Lubrication System: In a wet sump, the oil pump sucks oil from the bottom of the oil pan through a tube, and

then pumps it to the rest of the engine. In a dry sump, extra oil is stored in a tank outside the engine rather than in the oil pan. There are at least two oil pumps in a dry sump -- one pulls oil from the sump and sends it to the tank, and the other takes oil from the tank and sends it to lubricate the engine. The minimum amount of oil possible remains in the engine.

A dry-sump system has several advantages over wet, but the main one is additional power. Because there is only a minimum of oil in the pan, windage‚oil clinging to or splashing against the

rotating assemblies of the engine is greatly reduced.

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In addition to evacuating oil from the pan, the external oil pump creates a vacuum inside the pan

and block that further increases horsepower by improving ring seal. Other advantages of a dry-

sump system are increased oil capacity because of the external tank, the ability to easily add remote

oil coolers, and because the pan doesn‚store oil, it can be quite shallow to allow for lower engine

placement.

Mist Lubrication System

In two stroke engines the charge is compressed in the crank case and as such it is not suitable to

have the lubricating oil in the sump.Therefor such engines are lubricated by adding 3% to 6%oil in

the fuel tank itself.

The oil and fuel mixture is inducted through th carburetor.. The fuel gets vapourised and the oil in

the form of mist goes into the cylinder through the crankcase.The oil that impinges the crankcase

walls lubricate the main and connecting rod bearings and the rest of the oil lubricates the

piston.,pistonrings and cylinder.

The main advantge lis in the simplicity and low cost as the system does not require any oil

pump,filter ,etc.


To understand the purpose and need of cooling and lubrication systems in IC engines and and how

this systems are incorporated in these engines.

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Questions

1) Why a cooling system is necessary in an engine? 2) Define Air cooling system. 3) Define Water cooling system. 4) Compare between Air cooling and water cooling system.

5) What is the necessity of engine lubrication? 6)What are the objects of lubricating engine?

7) Explain different methods of engine lubrication system 8) What are the requirements of lubrication system?

9) Write the properties of lubricants. 10) List the functions of lubrication system. 11) Write the types of lubricants. 12) Compare between Air Cooling and Water Cooling. 13) Explain the pump circulator Water cooling system with the help of neat sketches. 14) Describe briefly the various components of Water Cooling system.

15) What are the requirements of lubrication system? 16)With the simple sketch explain about splash lubrication system.

17)With simple sketch explain about pressure lubrication system.

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STUDY MATERIAL





Title: < METAL CASTING PROCESS>


<To understand the metal casting process.>

Methodology:

0 – 15Minutes : The process :

16 – 30 Minutes Brief explanation of moulding processes and their types:

31 – 45 Minutes Gating system,melting and pouring:


Brief Content:

The content gies the essential elements in casting process especially the process, moulding ,gating

system ,melting puring and cleaning of castings

Detailed content

2.5.1 Introduction:

• Casting process is one of the earliest metal shaping techniques known to human being.

• It means pouring molten metal into a refractory mold cavity and allows it to solidify.

• The solidified object is taken out from the mold either by breaking or taking the mold apart.

• The solidified object is called ―casting‖ and the technique followed in method is known

as ―casting process‖.

• A plant where the castings are made is called a ―foundry‖.

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Classification of casting processes:

2.5.2 Sand Moulding:

• Mould is the cavity of the required shape made in moulding sand or in other material.

• Pattern is the model of the required casting made in wood, metal or plastics.

• The important processes involved in foundry are

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i) pattern making

ii) mould making

iii) casting

Vents, which are placed in molds to carry off gases produced when the molten metal comes

into contact with the sand in the molds and core. They also exhaust air from the mold cavity as

the molten metal flows into the mold.

2.5.3 Gating System:

1. Minimize turbulent flow so that absorption of gases, oxidation of metal and erosion of

mould surfaces are less

2. Regulate the entry of molten metal into the mould cavity

3. Ensure complete filling of mould cavity, and

4. Promote a temperature gradient within the casting so that all sections irrespective of size

and shape could solidify properly

5. Provide feeders or riser to take care of the liquid solid shrinkage of metals and alloys

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2.5.4 Melting and Pouring

• Several types of furnaces are available for melting metals and their selection depends on the

type of metal, the maximum temperature required and the rate and the mode of molten metal

delivery.

• Before pouring provisions are made for the escape of dissolved gases. The gating system

should be designed to minimize the turbulent flow and erosion of mould cavity. The other

important factors are the pouring temperature and the pouring rate.


To have good knowledge of the elements in casting process and their purpose.

Questions

1.How casting processes are classified according to the pattern and moulds

used. 2Whatis thpurpose of gating system in casting process.

3.What is the purpose of vents in sand moulding?

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STUDY MATERIAL





Title: < PATTERN MAKING AND MOULDING PROCESSES>


<To gain knowledge about patterns,foundry sands and moulding processes..>

Methodology:

0 – 15Minutes : patter materials,types and allowances :

16 – 30 Minutes Composition and Propertis of foundry sands

31 – 45 Minutes Sand moulding and otheir special moulding processes. :


Detailed Content:

2.6.1 Patte rn Making:

Variety of patters are used in casting and the choice depends on the configuration of

casting and number of casting required.

Patte rn materials:

• Wood

• Metal

CI, Brass, Aluminium

• Plasters or gypsum cement

• Plastics

• Wax

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Types of Patterns:

1. Solid or single piece pattern 2. Split pattern 3. Loose piece pattern 4. Match plate pattern 5. Sweep pattern 6. Skeleton pattern 7. Segmental pattern 8. Shall pattern

(a)Split pattern (b) Follow-board (c) Match Plate (d) Loose-piece (e) Sweep (f) Skeleton pattern

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Patte rn allowances:

1. Shrinkage allowances 2. Machining or finish allowances 3. Draft or taper allowances 4. Distortion or camber allowances 5. Rapping or shake allowances

1. Contraction allowances / Shrinkage allowance

The pattern needs to incorporate suitable allowances for shrinkage; these are called contraction

allowances, and their exact values depend on the alloy being cast and the exact sand casting method

being used. Some alloys will have overall linear shrinkage of up to 2.5%, whereas other alloys may

actually experience no shrinkage or a slight "positive" shrinkage or increase in size in the casting

process. The shrinkage amount is also dependent on the sand casting process employed, for

example clay-bonded sand, chemical bonded sands, or other bonding materials used within the

sand. This was traditionally accounted for using a shrink rule, which is an oversized rule.

2. Draft allowance

When the pattern is to be removed from the sand mold, there is a possibility that any leading

edges may break off, or get damaged in the process. To avoid this, a taper is provided on the

pattern, so as to facilitate easy removal of the pattern from the mold, and hence reduce damage to

edges. The taper angle provided is called the Draft angle. The value of the draft angle depends upon

the complexity of the pattern, the type of molding (hand molding or machine molding), height of

the surface, etc. Draft provided on the casting 1 to 3 degrees on external surface.

3. Finishing or machining allowance

The surface finish obtained in sand castings is generally poor (dimensionally inaccurate), and

hence in many cases, the cast product is subjected to machining processes like turning or grinding

in order to improve the surface finish. During machining processes, some metal is removed from

the piece. To compensate for this, a machining allowance (additional material) should be given in

the casting.

4. Shake allowance

Usually during removal of the pattern from the mold cavity, the pattern is rapped all around the

faces, in order to facilitate easy removal. In this process, the final cavity is enlarged. To compensate

for this, the pattern dimensions need to be reduced. There are no standard values for this allowance,

as it is heavily dependent on the personnel. This allowance is a negative allowance, and a common

way of going around this allowance is to increase the draft allowance.Shaking of pattern causes

enlargement of mould cavity and results in a bigger casting.

5. Distortion allowance

During cooling of the mold, stresses developed in the solid metal may induce distortions in the cast.

This is more evident when the mold is thinner in width as compared to its length. This can be

eliminated by initially distorting the pattern in the opposite direction.

http://en.wikipedia.org/wiki/Allowance_(engineering)

http://en.wikipedia.org/wiki/Shrink_rule

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2.6.2 Sand Moulding

Foundry Sands:

Silica (SiO2) or silica mixed with other minerals

Good refractory properties - capacity to endure high temperatures High silica content in sand is required for this.

Small grain size yields better surface finish on the cast part

Large grain size is more permeable, allowing gases to escape during pouring

Irregular grain shapes strengthen molds due to interlocking, compared to round grains

Disadvantage: interlocking tends to reduce permeability

Binders :

Sand is held together by a mixture of water and bonding clay

Typical mix: 90% sand, 3% water, and 7% clay

Other bonding agents also used in sand molds:

Organic resins (e g , phenolic resins)

Inorganic binders (e g , sodium silicate and phosphate)

Additives are sometimes combined with the mixture to increase strength and/or permeability

Types of Sand Mold:

Green-sand molds - mixture of sand, clay, and water;

―Green" means mold contains moisture at time of pouring

Dry-sand mold - organic binders rather than clay

And mold is baked to improve strength

Skin-dried mold - drying mold cavity surface of a green-sand mold to a depth of 10 to 25 mm,

using torches or heating lamps

Mould making:

Moulding sand preparation :

• Mixing of sand

• Tempering of sand

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• Conditioning of sand

2.6.3 Types of molding Processes:

1. Sand casting

2. Shell mould casting

3. Plaster casting

4. Vacuum casting

5. Investment casting

6. Die casting 1. Sand Casting:

Moulding methods:

1. Bench moulding – small moulds

2. Machine molding process using jolt squeeze machines

3. Floor moulding – medium to large moulds

4. Pit moulding – very large and heavycastings

5. Sweep moulding – large and medium size

Advantages:

Cheapest

Large size

Complex & complicated shapes

All metals & alloys and some plastics can be cast

Disadvantages:

• Quite long

• High energy consuming process

• Difficult Working condition

• Highly skilled labour

• Productivity less

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ADVANTAGES:

1. No limit on size and shape 2. All metal can cast 3. Low equipment cost 4. Economical for low volume production

LIMITATIONS

1. Product give rough surface 2. Thin projection not practical 3. Machining always necessary

2. SHELL MOULD CASTING

• Mould - phenolic resign mixed with fine,dry silica in the presence of alcohol(no water) • Pattern is made of grey cast iron, aluminium or brass and is accurately machined

Applications: Brake drums, Bushings, cams, camshaft, piston, piston rings, small pulleys, motor

housing, cylinders, conveyor, rollers etc.,

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i. Expanded Polystyrene Process:

Uses a mold of sand packed around a polystyrene foam pattern which vaporizes when molten

metal is poured into mold

Other names: lost- foam process, lost pattern process, evaporative- foam process, and full- mold process

Polystyrene foam pattern includes sprue, risers, gating system, and internal cores (if needed)

Mold does not have to be opened into cope and drag sections

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Expanded polystyrene casting process: pattern of polystyrene is coated with refractory

compound;

Expanded polystyrene casting process: (2) foam pattern is placed in mold box, and sand

is compacted around the pattern;

Expanded polystyrene casting process: (3) molten metal is poured into the portion of the pattern

that forms the pouring cup and sprue. As the metal enters the mold, the polystyrene foam is

vaporized ahead of the advancing liquid, thus the resulting mold cavity is filled.

Applications:

– Mass production of castings for automobile engines

– Automated and integrated manufacturing systems are used to

• Mold the polystyrene foam patterns and then

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• Feed them to the downstream casting operation ii. Investment Casting

• The pattern is made by injecting semisolid or wax into a metal die in the shape of

a pattern • The pattern is removed and dipped in slurry of very fine slica and binders,ethyl

silicate and acid.

• The one piece mould is dried in the air and heated to a temperature of 90 to 175o c

for about 4 hours to drive off water for crystallization • The molten metal is then poured.

Applications:

Nozzles, buckets, vanes, blades, aircraft engines, frames, fuel systems, machine

tools and accessories, scientific instruments, cloth cutting machine, movie camera parts etc.,

iii. Permanent Mold Casting Processes • Economic disadvantage of expendable mold casting: a new mold is required for

every casting • In permanent mold casting, the mold is reused many times • The processes include:

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o Basic permanent mold casting

o Die casting

o Centrifugal casting

Uses a metal mold constructed of two sections designed for easy, precise opening and closing

• Molds used for casting lower melting point alloys are commonly made of steel or cast iron.

Applications:

• Due to high mold cost, process is best suited to high volume prod uction and can

be automated accordingly

• Typical parts: automotive pistons, pump bodies, and certain castings for aircraft

and missiles

• Metals commonly cast: aluminum, magnesium, copper-base alloys, and cast iron


To learn about patterns and foundry sands in detail and laso know different moulding

processes and their applications/

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Questions

1) Define pattern. 2) Name the common pattern materials.

3) State the advantages and disadvantages of pattern materials. 4) List out the various types of pattern.

5) List out the pattern allowances. 6) State the properties of molding band. 7) How the mould sand is prepared? 8) List out various types of molding? 9) Define molding 10) Define casting 11) What are the properties of good molding band? 12) Enumerate the properties of molding sand and explain any five in detail.

•

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STUDY MATERIAL





Title: < CASTING DEFECTS>


<To know about common defects in the casting and also means to avoid them/ .>

Methodology:

0 – 30 Minutes : Classification of casting defects their causes and remval

31 – 45 Minutes : Cleaning and inspection of castings


Brief Content:

Classification of casting defects,their causes and prevention Cleaning and inspection of castings

Detailed content

2.7.1 Casting Defects:

• Defects may occur due to one or more of the following reasons:

– Fault in design of casting pattern

– Fault in design on mold and core

– Fault in design of gating system and riser

– Improper choice of moulding sand

– Improper metal composition

Inadequate melting temperature and rate of pouring

Classification of casting defects:

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Casting defects

Surface Defect Inte rnal Defect Visible defects

Blow Blow holes Wash

Scar Porosity Rat tail

Blister Pin holes Swell

Drop Inclusions Misrun

Scab Dross Cold shut

Penetration Hot tear

Buckle Shrinkage/Shift

Surface Defects:

• These are due to poor design and quality of sand molds and general cause is poor ramming

• Blow is relatively large cavity produced by gases which displace molten metal from convex

surface. Scar is shallow blow generally occurring on a flat surface. A scar covered with a

thin layer of metal is called blister. These are due to improper permeability or venting.

Sometimes excessive gas forming constituents in moulding sand

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• Drop is an irregularly-shaped projection on the cope surface caused by dropping of sand.

• A scab when an up heaved sand gets separated from the mould surface and the molten

metal flows between the displaced sand and the mold.

• Penetration occurs when the molten metal flows between the sand particles in the mould.

These defects are due to inadequate strength of the mold and high temperature of the molten

metal adds on it.

• Buckle is a vee-shaped depression on the surface of a flat casting caused by expansion of

a thin layer of sand at the mould face. A proper amount of volatile additives in moulding

material could eliminate this defect by providing room for expansion.

Inte rnal Defects:

• The internal defects found in the castings are mainly due to trapped gases and dirty metal.

Gases get trapped due to hard ramming or improper venting. These defects also occur

when excessive moisture or excessive gas forming materials are used for mould making. • Blow holes are large spherical shaped gas bubbles, while porosity indicates a large

number of uniformly distributed tiny holes. Pin holes are tiny blow holes appearing just

below the casting surface. • Inclusions are the non- metallic particles in the metal matrix, Lighter impurities appearing

the casting surface are dross.

Visible Defects:

• Insufficient mould strength, insufficient metal, low pouring temperature, and bad design

of casting are some of the common causes.

• Wash is a low projection near the gate caused by erosion of sand by the flowing metal. Rat

tail is a long, shallow, angular depression caused by expansion of the sand. Swell is the

deformation of vertical mould surface due to hydrostatic pressure caused by moisture in

the sand.

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• Misrun and cold shut are caused by insufficient superheat provided to the liquid metal.

• Hot tear is the crack in the casting caused by high residual stresses.

• Shrinkage is essentially solidification contraction and occurs due to improper use of Riser.

• Shift is due to misalignment of two parts of the mould or incorrect core location.

2.7.2 CLEANING:

• ROUGH – removal of gates of risers

• SURFACE- removal sand , scale

• TRIMMING- removal of fins

• FINISHING – additional surface finishing operation

2.7.3 INSPECTION:

1. Destructive inspection method

2. Non destructive inspection method

1. Visual

2. Dimensional

3. Radiographic

4. Magnetic particle


To learn about casting defects in detail,causes and prevention and also know about

cleaning and inspetion of castings

Questions

1.How casting defects are classfied?

2.What are the main causes for casting deects.

3. List the inspection method for castings.

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STUDY MATERIAL





Title: < CUPOLA FURNACE>


<To gain knowledge about principle,construction and working of cupola.>

Methodology:

0 –5Minutes : Introduction to melting furnaces.

6 – 30 Minutes Description andVarious zones in cupola furnace.

31 – 45 Minutes : Working of cupola-Its advantags and limitations.

46– 50 Minutes Working of cupola:

Detailed Content:

2.8.1 Furnaces for Casting Processes:

Furnaces most commonly used in foundries are:

1. Cupolas 2. Direct fuel- fired furnaces 3. Crucible furnaces 4. Electric-arc furnaces 5. Induction furnaces

2.8.2 CUPOLA FURNACE:

Vertical cylindrical furnace equipped with tapping spout near base

Used only for cast irons

Although other furnaces are also used, the largest tonnage of cast iron is melted in cupolas

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The "charge," consisting of iron, coke, flux, and possible alloying elements, is loaded through a charging door located less than halfway up height of cupola

Cupolas are basically refractory lines vertical steel vessels that are charge with

alternating layers of metal, coke, and flux. They operate continuously, have high melting rates,

and produce large amounts of molten metal.

It consists of a large shell of steel plate lined with refractory. The charge, consisting or iron,

Coke, flux and possible alloying elements, is loaded through a charging door located less than

halfway up the height of the cupola.

The iron is usually a mixture of pig iron and scrap (including risers, runners, and sprues left

over from previous castings). Coke is the fuel used to heat the furnace. Forced air is introduced

through openings near the bottom of the shell for combustion of the coke.

The flux is a basic compound such as limestone that reacts with coke ash and other

impurities to form slag. The slag serves to cover the melt, protecting it from reaction with the

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environment inside the cupola and reducing heat loss. As the mixture is heated and melting of the

iron occurs, the furnace is periodically tapped to provide liquid metal for the pour.

2.8.3 Various Zones of Cupola Furnace Various numbers of chemical reactions take place in different zones of cupola. The

construction and different zones of cupola are : 1. Well The space between the bottom of the tuyeres and the sand bed inside the cylindrical shell of the

cupola is called as well of the cupola. As the melting occurs, the molten metal is get collected in this portion before tapping out. 2. Combustion zone The combustion zone of Cupola is also called as oxidizing zone. It is located between the upper of the tuyeres and a theoretical level above it. The total height of this zone is normally from 15 cm.

to 30 cm. The combustion actually takes place in this zone by consuming the free oxygen completely from the air blast and generating tremendous heat. The heat generated in this zone is

sufficient enough to meet the requirements of other zones of cupola. The heat is further evolved

also due to oxidation of silicon and manganese. A temperature of about 1540°C to 1870°C is achieved in this zone. Few exothermic reactions takes place in this zone these are represented as: C + O2 → CO2 + Heat Si + O2 → SiO2 + Heat

2Mn + O2 → 2MnO + Heat

3. Reducing zone Reducing zone of Cupola is also known as the protective zone which is located between the

upper level of the combustion zone and the upper level of the coke bed. In this zone, CO2 is

changed to CO through an endothermic reaction, as a result of which the temperature falls from

combustion zone temperature to about 1200°C at the top of this zone. The important chemical

reaction takes place in this zone which is given as under. CO2 + C (coke) → 2CO + Heat Nitrogen does not participate in the chemical reaction occurring in his zone as it is also the other

main constituent of the upward moving hot gases. Because of the reducing atmosphere in this zone, the charge is protected against oxidation.

4. Melting zone The lower layer of metal charge above the lower layer of coke bed is termed as melting zone of

Cupola. The metal charge starts melting in this zone and trickles down through coke bed and

gets collected in the well. Sufficient carbon content picked by the molten metal in this zone is

represented by the chemical reaction given as under. 3Fe + 2CO → Fe3C + CO2

5. Preheating zone Preheating zone starts from the upper end of the melting zone and continues up to the bottom level

of the charging door. This zone contains a number of alternate layers of coke bed, flux and metal

charge. The main objective of this zone is to preheat the charges from room temperature to about

1090°C before entering the metal charge to the melting zone. The preheating takes place in this

zone due to the upward movement of hot gases. During the preheating process, t he metal charge

in solid form picks up some sulphur content in this zone. 6. Stack The empty portion of cupola above the preheating zone is called as stack. It provides the passage to hot gases to go to atmosphere from the cupola furnace. Charging of Cupola Furnace

Before the blower is started, the furnace is uniformly pre-heated and the metal and coke charges, lying in alternate layers, are sufficiently heated up.

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The cover plates are positioned suitably and the blower is started.

The height of coke charge in the cupola in each layer varies generally from 10 to 15 cms. The

requirement of flux to the metal charge depends upon the quality of the charged metal and scarp, the composition of the coke and the amount of ash content present in the coke.

2.8.4 Working of Cupola Furnace The charge, consisting of metal, alloying ingredients, limestone, and coal coke for fuel and

carbonization (8-16% of the metal charge), is fed in alternating layers through an opening in the cylinder.

Air enters the bottom through tuyeres extending a short distance into the interior of the cylinder. The air inflow often contains enhanced oxygen levels.

Coke is consumed. The hot exhaust gases rise up through the charge, preheating it. This

increases the energy efficiency of the furnace. The charge drops and is melted.

Although air is fed into the furnace, the environment is a reducing one. Burning

of coke under reducing conditions raises the carbon content of the metal charge to

the casting specifications.

As the material is consumed, additional charges can be added to the furnace.

A continuous flow of iron emerges from the bottom of the furnace. Depending on the size of the furnace, the flow rate can be as high as 100 tones per hour. At the metal melts it is refined to some extent, which removes contaminants. This makes this process more suitable than electric furnaces for dirty charges.

A hole higher than the tap allows slag to be drawn off.

The exhaust gases emerge from the top of the cupola. Emission control technology is used

to treat the emissions to meet environmental standards.

Hinged doors at the bottom allow the furnace to be emptied when not in use.

Type of Molten Metal Cupola is employed for melting scrap metals or (over 90 %) of the pig iron used in

the production of iron castings.

Gray Cast iron, nodular cast iron, some malleable iron castings and some copper base alloys can

be produced by Cupola Furnace.

Heat Ene rgy Source The cupola is a tubular furnace which produces cast iron by melting scrap and alloys using

the energy generated from the oxidation (combustion) of coke, a coal derivative.

Advantages

It is simple and economical to operate.

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A cupola is capable of accepting a wide range of materials without reducing melt quality. Dirty,

oily scrap can be melted as well as a wide range of steel and iron. They therefore play an important role in the metal recycling industry Cupolas can refine the metal charge, removing impurities out of the slag.

From a life-cycle perspective, cupolas are more efficient and less harmful to the environment than electric furnaces. This is because they derive energy directly from coke rather than from electricity that first has to be generated. The continuous rather than batch process suits the demands of a repetition foundry.

Cupolas can be used to reuse foundry by-products and to destroy other pollutants such as

VOC from the core- making area.

High melt rates

Ease of operation

Adequate temperature control

Chemical composition control

Efficiency of cupola varies from 30 to 50%.

Less floor space requirements comparing with those furnaces with same capacity.

Limitations Since molten iron and coke are in contact with each other, certain elements like si, Mn are

lost and others like sulphur are picked up. This changes the final analysis of molten metal.

Close temperature control is difficult to maintain


To know th construction detailed aorking ,operation and various zones of cupola furnace.

Questions 1.What metals can be melted in cupola.

2.Describe varius zones in cupola.

3.What are the advantages of cupola furnace.

4.List the limitations of cupola furnace.

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STUDY MATERIAL


BE (All branches) I /I&II EBU12DT095 2



Title: <METAL FORMING PRINCIPLES AND INTRODUCTION>


<To gain knowledge about various forming, joining and machining processes>

Methodology:

0 – 15Minutes : Introduction to metal forming and a brief discussion about different

forming process

16 – 25 Minutes : Material considerations

26 – 30 Minutes : Cold, warm and hot working

31 – 35 Minutes : Effects of friction

36 – 45 Minutes : Classification of bulk deformation process


Brief Content:

Introduction to different forming process

Material considerations in forming

Frictional effects

Bulk deformation process

Detailed Content:

This part contains the detailed notes of the terminologies, considerations, temperature

effects and classification of metal forming process

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3.1.1 OVERVIEW OF METAL FORMING

Definitions

Plastic Deformation Processes

Operations that induce shape changes on the work piece by plastic deformation under

forces applied by various tools and dies.

Bulk Deformation Processes

These processes involve large amount of plastic deformation. The cross-section of work

piece changes without volume change. The ratio cross-section area/volume is small. For most

operations, hot or warm working conditions are preferred although some operations are carried out

at room temperature.

Sheet-Forming Processes

In sheet metalworking operations, the cro ss-section of work piece does not change—the

material is only subjected to shape changes. The ratio cross-section area/volume is very high.

Sheet metalworking operations are performed on thin (less than 6 mm) sheets, strips or coils

of metal by means of a set of tools called punch and die on machine tools called stamping presses.

They are always performed as cold working operations.

Material considerations

Material Behavior

In the plastic region, the metal behavior is expressed by the flow curve:

σ = Κεn

where, K is the strength coefficient and n is the strain- hardening (or work-hardening) exponent. K

and n are given in the tables of material properties or are calculated from the material testing

curves.

Flow stress

For some metalworking calculations, the flow stress Yf of the work material (the

instantaneous value of stress required to continue deforming the metal) must be known:

Yf = Κ

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Average (mean) flow stress

In some cases, analysis is based not on the instantaneous flow stress, but on an average value

over the strain-stress curve from the beginning of strain to the final (maximum) value that

occurs during deformation:

=K n

Y f Y f

Y Specific energy u

f

The mean flow stress is defined as

K n

Yf f

1 n

Stress-strain curve indicating location of averag e flow

stress Y f in relation to yield strength Y and fi nal flow

stress Yf

where εf is the maximum strain value during deformation.

Work-hardening

It is an important material characteristic since it determines both the properties of the

workpiece and process power. It could be removed by annealing.

3.1.2 Temperature in metal forming

The flow curve is valid for an ambient work temperature. For any material, K and n depend

on temperature, and therefore material properties are changed with the work temperature:

log

K

n Increase in the

work temperature

log True stress -strain curve showing decrease in strength coefficient K and strain -hardening exponent n with work

temperature

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There are three temperature ranges-cold, warm, and hot working:

C o l d Warm H ot

w o rkin g w o rkin g w o rkin g

Te mp er ature r ang e f or diffe rent met al fo rming

operations. TA is the ambi ent (room) temperature,

TA 0.3Tm 0.5Tm 0.75Tm Tm and Tm is the w ork met al melting tem per ature

Cold working is metal forming performed at room temperature.

Advantages: better accuracy, better surface finish, high strength and hardness of the

part, noheating is required.

Disadvantages: higher forces and power, limitations to the amount of forming, additional

annealing for some material is required, and some material are not capable of cold working.

Warm working is metal forming at temperatures above the room temperature but

bellow therecrystallization temperature..

Advantages: lower forces and power, more complex part shapes, no annealing

is required.

Disadvantages: some investment in furnaces is needed.

Hot working involves deformation of preheated material at temperatures above the

re-crystallizationtemperature.

Advantages: big amount of forming is possible, lower forces and power are required,

formingof materials with low ductility, no work hardening and therefore, no additional annealing is

required.

Disadvantages : lower accuracy and surface finish, higher production cost, and shorter tool life.

3.1.3 Friction effects

Homogeneous Deformation

If a solid cylindrical workpiece is placed between two flat platens and an applied load P is increased until the stress reaches the flow stress of the material then its height will be reduced

from initial value of hoto h1. Under ideal homogeneous condition in absence of friction between

platens and work, any height reduction causes a uniform in-crease in diameter and area from

original area of Ao to final area Af.

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Inhomogeneous deformation

In practice, the friction between platens and workpiece cannot be avoided and the latter

develops a ―barrel‖ shape. This is called inhomogeneous deformation and changes the load

estimation as follows

do

P Yf ks Af Yf1 3h A

f

o

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BULK DEFORMATION PROCESSES

3.1.4 Classification of Bulk Deformation Processes

Basic bulk deformat ion processes

(a) rolling, (b) forging, (c) extrusion, (d) drawing

Rolling: Compressive deformation process in which the thickness of a plate is reduced

bysqueezing it through two rotating cylindrical rolls.

Forging: The work piece is compressed between two opposing dies so that the die shapes

areimparted to the work.

Extrusion: The work material is forced to flow through a die opening taking its shape

Drawing: The diameter of a wire or bar is reduced by pulling it through a die opening

(bardrawing) or a series of die openings (wire

drawing) Expected Learning outcome

To understand the effect of stress, temperature and frictional forces in bulk deformation of metals

and consequences of the same. And also know the classification of buk deformation processes.

Questions

1. Define the hot working and cold working.

2 Give some examples of hot working process. 3. State some examples of cold working process. 4.Compare cold working and hot working of

metals. 5.What are the limitation. of cold working. 6.What are the merits of coldworking. 7.List the advantages of hot working of metals. 8.List

the limitations fo coldworking of metals. 9.Name the

disadvantages of coldworking of metals.

10.List different buk deformation processes and define them with simple sketch

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STUDY MATERIAL


BE (All branches) I / I or II EBU12DT095 2



Title: < BULK DEFORMATION PROCESSES-ROLLING AND FORGING >


< To gain knowledge about various forming, joining and machining processes >

Methodology:

0 – 5 Minutes : Introduction to Rolling and steps involved in it

6 – 10 Minutes : To display the various pictures of rolling process

11 – 25 Minutes : Explanation on different types of rolling

26 – 30 Minutes : Introduction to forging

36 – 45 Minutes : Explanation on different types of forging


Brief Content:

Introduction to rolling

Steps involved in rolling

Different types of rolling

Introduction to forging

Different types of forging

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Detailed Content:

This part contains the detailed notes aboutthe different types of rolling and forging

processes.

3.2.1 Rolling

Definition

Rolling is a Bulk Deformation Process in which the thickness of the work is reduced by

compressive forces exerted by two opposing rolls:

The process of flat ro lling

Steps in rolling

The preheated at 1200 oC cast ingot (the process is known as soaking) is rolled into one of

the three intermediate shapes called blooms, slabs, or billets.

v Bloom has a square cross section of 150/150 mm or more

v Slab (40/250 mm or more) is rolled from an ingot or a bloom

v Billet (40/40 mm or more) is rolled from a bloom

These intermediate shapes are then rolled into different products as illustrated in the figure:

Production steps in rolling

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Next pictures show some production steps in flat and shape rolling:

Powerful tongs lift an ingot fro m the soaking pit

where it was thoroughly heated to the rolling

temperature

Structural shapes are rolled fro m b looms on

mills equipped with grooved rolls

Steel bloo m enters the rolling mill

Hot saw cuts rolled shapes to customer length after

delivery from the finishing rolling mill

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Flat rolling

Work velocity

Vf

Roll velocity

Vr

Vo

Neutral point L

Side view of flat ro lling and the velocity diagram indicating work and roll velocit ies along the contact length L

The work is squeezed between two rolls so that it thickness is reduced by an amount called the draft, d

d = to-tf

If the draft is expressed as a fraction of the starting block thickness, it is called reduction, r:

r = d/to

Rolling increases the work width from an initial value of wo to a final one of wf, and this is

called spreading.

The inlet and outlet volume rates of material flow must be the same, that is,

towovo = tfwfvf

where vo and vfare the entering and exiting velocities of the work. The point where roll velocity

equals work velocity is known as the no-slip point or the neutral point. The true strain and the mean flow stress are defined by

to

K n

true strain lnt f , and mean flow stress Yf 1 n

Friction occurs with a certain coefficient of friction µ on either sides of no-slip point. Both friction forces act in opposite directions and are not equal. The entrance force is bigger so that the resulting

force pulls the work through the rolls. The maximum possible draft d max depends on µ and roll radius R and is given by

dmax = µ2R

The rolling force F is estimated as

F Yf wL

where L is the contact length, approximately

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L R(to t f The power P required to drive each roll is

P=2πNFL where N is the rotational speed of the roll.

Shape rolling

The work is deformed by a gradual reduction into a contoured cross section (I-beams,

L-beams, U-channels, rails, round, squire bars and rods, etc.).

Ring rollig

Thick-walled ring of small diameter is rolled into a thin-walled ring of larger diameter:

Ring rolling used to reduce the wall th ickness and increase the diameter of a ring

Thread rolling

Threads are formed on cylindrical paIrts by rolling them between two thread dies:

Thread rolling with flat d ies Gear rolling Gear rolling is similar to thread rolling with three gears (tools) that form the gear profile on the work.

Work Gear rolls

Gear rolling between three gear roll tools

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3.2.2 Forging

Definition

Forging is a Bulk Deformation Process in which the work is compressed between two dies.

According to the degree to which the flow of the metal is constrained by the dies there are

three types of forging:

Œ Open-die forging

• Impression-die forging

Ž Flashless forging

Three types of forging: (a) open-die forg ing, (b) imp ression die forging, and (c) flashless forging

Open-die forging

Known as upsetting, it involves compression of a work between two flat dies, or platens.

Force calcula-tions were discussed earlier.

Sequence in open-die forging illustrating the Open-die forging of a multi diameter shaft unrestrained flow of material. Note the barrel shape that forms due to friction and inhomogeneous deformation in the work

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Impression-die forging

In impression-die forging, some of the material flows radially outward to form a flash:

Schematics of the impression-die forging process

showing partial die filling at the beginning of flash

formation in the center sketch, and the final shape

with flash in the right-hand sketch

Stages (from bottom to top) in

the formation of a crankshaft

by hot impression-die forging

Estimation of the maximum force F can be approximately done by

F = KfYfA

where Kf is the shape factor ranging fro m 6 to 10, b igger for more co mp lex shapes, Yf is the yield strength

of the material at work temperature, A is the projected area of the part, including flash.

Flashless forging

The work material is completely surrounded by the die cavity during compression and no

flash is formed:

Flashless forging: (1) just before in itial contact with the workpiece,

(2) partial compression, and (3) final push and die closure. Symbol v indicates motion, and F - applied force.

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Most important requirement in flash less forging is that the work volume must equal the space in

the die cavity to a very close tolerance. For force estimation, the same equation as in impression-die

forging is applied.

Coining

Special application of flash less forging in which fine detail in the die are impressed into the top

and bottom surfaces of the work piece. There is a little flow of metal in coining.

Coin ing operation: (1) start of cycle,

(2) co mpression stroke, and

(3) ejection of fin ished part

Forging machines

The next figures show some examples of the common forging machines-hammers and presses:

Drop forging hammer, fed by conveyor and heating unit

at the right of the scene.

A 35 000-ton forging press. In the foreground is a 120-kg, 3-

m aluminum part that has forged on this press

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To know about various rolling and forging process to obtain different shapes and sizes by

bulk dwformation by these processes.

Questions

1. Define forging. 2. What are the applications of the forging process? 3. Name the two classifications of forging.

4. Name the hand forging operations used in the hot working process. 5. What is rolling?

6. Name some examples of rolling operations. 7. State the principle of rolling operation.

8. Name the two types of rolling process. 9 Differentiate the process of hot rolling and cold rolling processes with

neat diagrams.

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STUDY MATERIAL





Title: < BULK DEFORMATION PROCESSES-EXTRUSION AND WIRE DRAWING >


< To gain knowledge about various extrusion and deep drawing processes >

Methodology:

0 – 5 Minutes : Introduction to extrusion

11 – 25 Minutes : Explanation on different types of extrusion

26 – 30 Minutes : Force and power analysis in extrusion

31 – 45 Minutes : Wire and bar drawing

46 – 50 Minutes : Attendance & closure of class

Brief Content:

Extrusion and its types

Force and power analysis of extrusion

Wire and bar drawing

Detailed Content:

This part contains the detailed notes about the Extrusion and its types and wire and bar

drawing process.

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3.3.1 Extrusion

Definition

Extrusion is a Bulk Deformation Process in which the work is forced to flow through a

die opening to produce a desired cross-sectional shape.

Typical shapes produced by extrusion

Extrusion is performed in different ways therefore different classifications are available:

v Direct and indirect extrusion

v Hot and cold extrusion

v Continuous and discrete extrusion

Direct and indirect extrusion

(Left) Direct extrusion to produce hollow or semihollow cross section.

(Right) Direct extrusion to produce solid cross section. Schematic shows

the various equipment components.

Force and powe r analysis in extrusion

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The ram force, F, is estimated as

F = p Ao

where Ao is the billet cross -sectional area, and p is the

ram pressure,

where Do is the original diameter of the billet, L is the

length of the billet in the die, and εx is the extrusion strain,

εx = a+b ln(Ao /Af ),

a and b being the empirical constants, usually

a=0.8 and b=1.2~1.5.

Power required is calculated as P = Fv , where v is

the ram velocity.

In indirect extrusion (backward, inverse

extrusion) the material flows in the

direction opposite to the mo-tion of the

ram to produce a solid (top) or a hollow

cross section (bottom).

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3.3.2 Wire and Bar Drawing

Definition

Wire and Bar Drawing is a Bulk Deformation Process in which the cross-section of a bar,

rod or wire is reduced by pulling it through a die opening, as in the next figure:

Drawing of a rod, bar, or wire

Bar drawing is a single-draft operation. By contrast, in wire drawing the wire is drawn

through a series of dies, between 4 and 12.

The draft, d, is defined as

d = Do - Df

and reduction, r, is given by

r = d/Do


To know about different types of extrusion processes and drawing operation for wire and

rods and the principles behind the same.

Questions

1. Define extrusion. 2. State the applications of the extrusion process. 3. Draw and explain the working principles of extrusion process. 4. Explain the following processes with the neat sketch a.Drawing

b.Rolling

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STUDY MATERIAL





Title: < METAL JOINING PROCESSS –GAS WELDING AND GAS CUTTING>


< To gain knowledge about gas welding and gas cutting processes >

Methodology:

0 – 5 Minutes : Introduction to joining

6 – 10 Minutes : Welding and its types.

11 – 25 Minutes : Gas Welding Equipment details and mechanism

26 – 35 Minutes : salient features and limitations

36 – 40 Minutes : Gas or flame cutting process

41 – 45 Minutes : Characteristics of filler rod and Role of flux


Brief Content:

Introduction to joining process

Need for joining

Introduction to welding

Types of welding

Gas welding

Equipments of gas welding process

Mechanism of gas welding

Salient features of gas welding

Advantages, limitations and applications of gas welding

Detailed Content:

This part contains the detailed notes about the Gas welding process.

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3.4.1 JOINING PROCESSES

Almost all products are assemblies of a large number of components. Some of the components or sub-

assemblies can move with respect to each other, others are physically fixed together, with no relative

motion possible. The first type of connection is called a kinematic joint, and the second type is called a

rigid joint (or a structure). Both types of joints are important in manufacturing, and there are many ways

of achieving such joints. The process and methods used for joining depend on the type of joint, the required

strength, the materials of the components being joint, the geometry of the components, and cost issues. IN

this lecture, we study some of the common methods of joining.

Why do we need joining?

To restrict some degrees of freedom of motion for components (i.e. to make mechanisms).

A complex shaped component may be impossible/expensive to manufacture, but it may

be possible/cheaper to make it in several parts and then join them.

Some products are better made as assemblies, since they can be disassembled for

maintenance.

Transporting a disassembled product is sometimes easier/feasible compared to

transporting the entire product.

3.4.2 Fusion Welding

Welding is the most common joining process for metals. In fusion welding, the joint is made by

melting the metal at the interface, so that upon solidification, the components are fused, or joined

together. In many cases, extra metal is melted along the joint, to completely fill the joint region.

Types of fusion welding:

i. Gas welding

ii. Electric arc welding

iii. Thermit welding

3.4.3 Gas welding:

Gas welding process uses heat from the burning of the fuel gas, accelerated by pure

oxygen to reach a temperature of about 3000°C. This temperature is sufficient to heat and

melt many materials. Gas welding or Oxy Fuel Welding (OFW) was for many years referred

to as oxyacetylene welding due to the common use of acetylene as fuel gas. But today with

the introduction of fuels gases such as coal gas, propane, hydrogen etc. it is more

appropriately called oxy-fuel welding.

Gas welding is most suitable when

Portability is necessary.

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A welding of thin material is required. Amount of heat applied is to be varied and controlled.

3.4.4 Gas Welding Equipme nt:

i. Oxygen and acetylene gas cylinders. ii. Regulators and valves to control the flow of the gases. iii. Gauges to measure the gas pressure. iv. Hoses, connections and check valves to carry the gases to the torch. v. A torch to mix the gases and the means to direct the flame. vi. Safety equipment.

a. Goggles b. Gloves c. Face shield d. Protective clothing

i.Oxygen and acetylene cylinders:

The welding gases namely oxygen and acetylene are delivered to the user in a highly

compressed state in steel cylinders, which are made to rigid specifications set-up jointly

by the manufacturers, government organizations, and insurance agencies. High-grade

steel is used for the construction of high-pressure industrial gas cylinders. The wall

thickness of these cylinders is usually 6.5 mm. The general shape and size of the cylinder

is shown in Figure. A removable steel cap protects the cylinder valve. Oxygen cylinders

contain 99% pure oxygen at about 154 kgf/cm2 (15.4 MPa) at 2 1°C. A full cylinder has a

weight of about 80 kg.

Acetylene cylinder is a welded steel tube filled with a spongy material such as balsa

wood or some other absorptive material which is saturated with a chemical solvent called

acetone. Acetylene is usually obtained in portable storage tanks that hold up to 300 cubic feet

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of gas at 1.7 MPa. Acetylene is not safe when stored as gas above 2 kgf/cm2 (0.2 MPa)

otherwise it decomposes and explodes. It is usually dissolved in acetone. The wall thickness

of the acetylene cylinders is 4.5 mm. Acetylene leakage result in highly explosive mixture

when it mixes with air.

ii. Regulators:

The primary purpose of oxygen and acetylene regulators is to reduce the high gas

pressures safely and efficiently to the working pressure limits and to maintain the pressure

within close limits as per the welding requirements. Figure shows a commonly used

regulator.

iii. Pressure gauges:

Pressure gauges are important equipment in a gas welding set up. The regulators are

equipped with pressure gauges, which indicate the amount of pressure in the cylinder and the

amount of the working pressure.

iv. Hoses, connections and check valves:

The hoses required for gas welding are usually made of oil resistant reinforced rubber and

can withstand difficult working environmental conditions. Acetylene hose is red and oxygen

hose is green. The fittings provided on the red coloured acetylene gas hose is left handed.

This is done to prevent accidental connection to the oxygen line. The oxygen hose is

connected with right hand fittings.

v. Check valves:

Check valve is an important safety device on any gas welding system. These valves allow

flow in only one direction and thus prevents any backpressure from the flame or gas from

moving to the tank.

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vi. Welding torches:

The welding torch shown in Figure body serves as a handle so the welder can hold and

direct the flame while welding. Beyond the handle the torch is equipped with a means of

attaching the mixing head and welding tip. The mixing head combines the two gases namely

oxygen and acetylene. The amount of mixed oxygen and acetylene is the only amount that is

contained from the mixing head to the tip orifice. The amount mixed is very small as any

attempt to mix more may result in violent explosion.

vii. Torch tip:

This is another important equipment in gas welding. The selection of torch tip is governed

by the,

a. Gases to be used, b. Work material to be welded.

If the torch tip is too small for the material to be welded, the volume of the heat

required to melt the material will be slowly reached. The torch body fits at one end of the

mixing chamber whereas the torch tip is screwed at the other end of the mixing chamber.

However in some cases the torch tip and mixing chamber are one composite unit. Copper is

preferred for the construction of torch tips because of its good thermal conductivity as

compared to steel which has low thermal conductivity.

viii. Safety equipments:

The safety equipments are compulsory before doing welding. Goggles with coloured

lenses should be worn so as to protect the eyes from the harmful radiations of ultra-violet and

infrared rays. One can also use the head shield if proper goggle is not available. The gloves

should be worn so as to protect hands from injury. If possible, welder should use the

protective clothing while performing welding operations.

3.4.5 Mechanism of Gas welding:

Out of various gas welding methods, oxy-acetylene welding is mostly used. This is

discussed below.

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i. In this method, metals are joined by using the heat of combustion of an oxygen/air

and fuel gas mixture. ii. The fuel gas may be acetylene, hydrogen. iii. Heat is produced in the form of flame. iv. This heat melts and fuses together the edges of the parts to be welded. v. The filler metal is added to complete the weld. vi. Depending on mixture of oxygen and other fuel gas, welding is designated. e.g. Oxy-

hydrogen etc.

Salient features of Gas welding:

It is a manual process in which the metal surfaces to be joined are melted

progressively by heat from a gas flame, with or without filler metal, and are caused to

flow together and solidify without the application of press ure to the parts being

joined.

The most important source of heat for gas welding is the oxy-acetylene welding torch.

The simplest and most frequently used gas welding system of consists compressed-

gas cylinders, gas regulators, hoses, and a welding torch.

Oxygen and fuel gas are stored in separate cylinders. The gas regulator attached to

each cylinder (fuel gas or oxygen) controls the flow of gas from the cylinder to the

flexible rubber hose that delivers the gas to a gland attached to the appropriate inlet on

the welding torch.

At the torch, the gas passes through a inlet control valve and into a mixing chamber;

the mixed gases then pass through the welding tip and produce the flame at the exit

end of the tip.

Advantages:

The equipment is simple and less costly.

The initial cost and maintenance of the welding equipment is relatively low in

comparison with other welding methods.

The welding equipment's can be easily transported to the welding place. 3. Majority

of metals can be welded.

Suitable for the cases where the rate of heating and cooling is relatively slow.

The outer envelope of the flame acts as a shield to keep the oxygen and nitrogen in

the air from combining with the metal to form harmful oxides and nitrides. It may be used in cutting of steel and also preheating of jobs for certain operations.

Limitations:

The process is quite slow as compared to arc welding.

Harmful thermal effects are aggravated by prolonged heat. This often results in

increased grain growth, more distortion and in some case a loss of corrosion

resistance.

Fluxes used in welding operations produces fumes, which arc irritating to the e yes,

nose, throat, and lungs.

Difficulty in handling gases.

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Applications :

Gas welding finds applications in a large number of manufacturing, construc tion and service

industries. For example,

Sheet metal fabrication and repair.

Plant maintenance and repair.

Bicycles.

Tube and pipe industries.

Water, oil and natural gas transmission pipe line. Radiators.

3.4.6 Gas / Flame cutting:

Iron and steel sheets and plates can be cut by using Oxy-acetylene flame. The flame

cutting equipment is similar to that for gas welding.

Oxyacetylene Gas Cutting process:

In this, a cutting torch is used which resembles a welding torch; but the tip of the

cutting torch has a hole at the center with a set of holes surrounding it. Through the central

hole a stream of oxygen issues and oxyacetylene mixture comes out from the holes around.

When the torch is lighted and used, the oxyacetylene flame preheats the metal and the oxygen

oxidizes it in a narrow gap. The slag and molten metal formed are blown away by the oxygen

jet. Metals up to 750 mm thick have been cut. It must be remembered that this method is

almost exclusively used to cut ferrous metals and in particular steel.

Application:

This cutting technique is very much used in ship building industry, fabrication of

heavy structural items etc.

3.4.7 Filler rods :

Filler metals are used to provide additional materials to the weld zone during the

welding. These are available as rod or wire made of metals compatible with those to be

welded.

Characteristics:

These consumable filler rods may be bare or they may be coated with flux. Filler rods

are available in standard lengths of 36" and diameters varying from 1/16" to 1/ 4". Filler rods

have a thin coating of copper in order to prevent it from rusting during storage. The filler

materials (welding rods) as listed in Table can be used for gas welding of low carbon steels.

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Welding rods Che mical composition

Low carbon steel 0.08%C, 0.36%Mn, 0.13%Cr, 0.013%Ni, 0.2%P

Manganese steel 0.14%C, 0.81%Mn, 0.12%Si, 0.25%Ni

Chromium steel 0.24%C, 0.42%Mn, 0.96%Cr, 0.17%Ni, 0.35%S

Role of Flux:

The purpose of the flux is to generate a gaseous shield in and around the welding zone

so as to prevent the oxidation of the surfaces of the parts to be welded. The flux enables to

dissolve and remove oxides and other substances from the workpiece and thus provides a

strong joint.

The requirements of a good quality flux are:

The flux should be able to melt easily and have a melting point lower than the parent

material and filler metal.

It should able to react quickly with metallic oxides so that the oxides are completely

dissolved by the time the molten pool solidifies.

It should have no undesirable effect on the metal.

Its specific gravity should be lower than the parent and filler metals so that the slag

formed should float over the molten metal pool.

It should control the surface tension and flowability of the molten metal

pool. It should act as cleaning agent to clean the metal surfaces.

Generally in case of carbon steel, calcium oxide dissolved in liquid is used for gas

welding. Boric acid (H3B303), Borax (N28407), Di-sodium hydrogen phosphate (Na2HPO4)

etc. are mainly used as the fluxes for the gas welding of copper and copper base alloys. For

welding aluminium and its alloys, sodium chloride is preferred.


To learn about the welding processes and their types, Gas Welding Equipment details

and unserstand thier mechanism,salient features and limitations, Gas or flame cutting

process,Characteristics of filler rod and Role of flux.

Question

1.. What are the different methods of metal joining process?

2. Define welding. 3. Name some types of welding. 4. What is meant by fusion welding process? 5. Define arc welding. 6. Define gas welding.

7. Name the equipments used in gas welding process. 8. Name the different types of gas flames.

9. Write any two advantages of gas welding process. 10.Explain briefly about flame cutting with sketch.

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STUDY MATERIAL





Title: < METAL JOINING PROCESSS –ARC WELDING AND OTHER PROCESSES>


<To gain knowledge about arc welding and other types of welding processes>

Methodology:

0 – 15 Minutes : Arc welding and its types

16 – 30 Minutes : Arc welding equipments

31 – 35 Minutes : Comparison of AC and DC arc welding

36 – 40 Minutes : Salient features of Arc welding

41 – 45 Minutes : Other welding processes


Brief Content:

Arc welding and its types

Electric arc welding

Arc welding equipments

Comparison of AC and DC arc welding

Salient features of Arc welding

Resistance Welding

Submerged Arc Welding

Thermit Welding

Detailed Content:

This part contains the detailed notes about the arc and other welding process.

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3.5.1 Different Types of Arc Welding

Arc welding is one of the most common kinds of welding. The concentrated heat of an

electric arc joins metal by fusing the parent metal to a joint using a consumable electrode.

Direct or alternating current could be used, and which one depends on the welding material

and the electrode. There are different forms of arc welding,

Flux-cored arc welding (FCAW) uses tubular electrodes that are filled with flux. It's much

less brittle than the coatings on SMAW electrodes and preserves most of the alloying

benefits. The emissive fluxes shield the welding arc from the air, or shielding gases might be

used if nonemissive fluxes are required. It's popular when welding heavy sections an inch or

more thick thanks to the higher weld- metal deposition rate.

Gas metal arc welding (GMAW), also known as MIG welding, shields the welding arc with

a gas such as argon or helium or even a mixture. Deoxidizers in the electrodes can prevent

oxidation which makes it possible to weld mulitple layers. It's a simple, versatile, a nd

economical welding process. The temperatures are also relatively low and it is used for thin

sheet and sections. It can easily be automated.

Gas tungsten arc welding (GTAW) is also known as TIG welding. It uses tungsten

electrodes as one pole of the arc in order to create the required heat. The gas is argon, helium,

or a mixture of those two. Filler wires provide the molten material if it is necessary. This

process is good for thin materials and the filler wires are similar in composition to whatever is

being welded.

Plas ma arc welding (PAW) has ionized gases and electrodes that generate hot plasma jets

that are aimed at the welding area. These jets are extremely hot. The concentration of higher

energy is good for narrower and deeper welds as well as an increase in welding speeds.

Shielded metal arc welding (SMAW) is one of the simplest, oldest, and most versatile

welding methods. The arc comes from a coated electrode tip being touched to the workpiece

and then withdrawn to maintain the arc. The heat that is generated melts the tip, coating, and

base metal and the weld is formed out of that alloy when it solidifies. Slag that is formed and

protects the weld from oxides, inclusions, and nitrides has to be removed after every pass.

This is commonly used in pipeline work, shipbuilding, and construction.

Submerged arc welding (SAW) has a granular flux that is fed into the weld zone that forms

a thick layer, completely covering the molten zone and preventing sparks and spatter. It

allows for deeper heat penetration since it acts like a thermal insulator. The process is limited

to horizontal welds and used for high speed sheet or plate steel welding. It can be

semiautomatic or automatic. The flux can be recovered and treated then used again. This

method provides 4-10 times as much productivity as shielded metal arc welding.

Resistance Welding:

Resistant welding is also one of the fusion welding technique that utilize heat and pressure to

make the welded joint. Required heat is generated at the junction due to flowing current

through it and resistance offered. The amount of heat generated is H = i2Rt where H is the

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heat generated w-sec, i is the current flowing, R is resistance of junction, t is the time for

which current flows. Principle of resistance welding can be explained with the help of

diagram shown in Figure. It consists of workpiece to be welded, two opposing electrodes a

mechanism to apply pressure to squeeze the workpieces, AC power supply to maintain the

current, a circuit breaker with times to stop the flowing current after a preset time.

Depending upon the joint to be make resistance welding can be divided into different

categories:

(a) Spot welding, (b) Seam welding, (c) Projection welding, and (d) Precision welding.

Submerged Arc Welding:

This is first arc welding technique to be automated. Submerged arc welding uses continuous

consumable electrode of the shape of a bare wire. The established arc is shielded by a cover

of granular flux. The electrode wire is fed continuously and automatically from a roll into the

welding zone. The flux is introduced in to the joint slightly ahead of the weld arch by gravity

from a hopper. Blanket of granular flux completely submerges the welding zone preventing

sparks, spatter and radiations. The portion of the flux near to the arc is melted, forming slag,

after mixing with molten metal. Slag can be removed from the weldment. Cover of granular

flux not only provides protection from the environment but also provides good thermal

insulation resulting in slow cooling imparting toughness and ductility to the joint.

Thermit Welding:

Thermit is a trade name for thermite. A mixture of Aluminium powder and iron oxide

that produces an exothermic reaction when ignited. In case of thermit welding heat is

produced by superheated molten metal form the chemical reaction of thermit. Filler metal is

obtained from liquid (molten) metal. Heat is generated when finely mixed powders of

aluminium and iron oxide in the ratio of 1 : 3 is ignited to a temperature of around 1300oC.

Following reaction takes place:

8AL + 3Fe3O4 → 9Fe + 4Al2O4 (slag) + heat

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Thermit welding has applications in joining of rail road rails, repair of cracks incastings and

forgings in ship building industries.

Electric Arc Welding:

The arc welding is a fusion welding process in which the welding heat is obtained

from an electric arc struck between the work(or base metal) and an electrode. The

temperature of the heat produced by the electric arc is of the order of 6000°C to 7000°C. Both

the direct current (D.C) and alternating current (A.C) may be used for arc welding, but the

direct current is preferred for most purposes. When the work is connected to the positive

terminal of the D.C welding machine and the negative terminal to an electrode holder, the

welding set up is said to have straight polarity. On the other hand, when work is connected to

negative and the electrode to a positive terminal, then the welding set up is said to have

reversed polarity. The straight polarity is preferable for some welds while for other welds

reversed polarity should be used.

3.5.2 Arc welding equipme nts:

The most commonly used tools and equipments for an arc welding process are:

i. DC welding machine:

The DC welding machine consists of a generator or a rectifier to produce a direct current

of sufficient strength to pass through the circuit, jump the arc gap, melt the electrode and

create a molten puddle in the base metal. The molten portion of the electrode will fuse into

the puddle of the base metal producing a weld. The important DC power sources are:

■ Motor generator

■ Engine driven generator

■ Rectifier.

ii. AC welding machine :

Different types of AC welding machines are available in the market. The two commonly

used machines in this category are:

■ Motor generator type

■ Transformer type. iii. Transforme r rectifier:

The transformer rectifier machine uses the power available in the workshop by adjusting

it for the welding purposes. Since the power available in the workshop has high voltage

but not amperage. So by using step down transformer the amperage is increased and

voltage is step downed from usual supply voltage of 220-440 volts to 50-90 volts.

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Rectifier changes the AC into DC. A rectifier is made up of diodes. Diodes allow the flow

of current in one direction only thus diodes resist the return flow of the alternating current

(AC). This energy cannot just disappear, so it changes into heat and the current flow is in one

direction only. It costs little in terms of maintenance and operating expenditure.

iv. Motor generator:

The motor generator power source simply uses an AC motor to run a DC generator.

This source is widely preferred because there are almost no fluctuations in the current.

v. Engine driven generator:

The engine driven generator uses a diesel engine to drive a DC generator. It comes

with a special throttle and governor to adjust the RPM to the DC generator for smooth DC

output. The portability of the system is its main advantage. Being engine driven, no external

power is required.

AC transforme r:

The AC transformer machine simply uses an AC transformer to step down the voltage

current for welding. This system is one of the simplest, it contains only a transformer, cooling

fan, and on-off switch.

vi. Electrode holder:

The electrode holder is one of the main part of the arc welding equipment held by

operator during welding. The electrode lead is fastened to the electrode holder either inside of

the handle, or to a lug. The handle itself is made of an insulating material, which has high

heat and electrical resistance qualities.

vii. Electrodes:

The arc welding uses both consumable and non-consumable electrodes. The proper

selection of an electrode for a given job is very important for producing sound and good

quality weld. The electrode manufacturer's catalogue contains the important information as

regards the selection of electrode, ampere settings, base metal preparation, welding

techniques, and welding positions etc.

viii. Gloves:

The gloves should be worn compulsorily to protect the hands from injury and heat.

ix. Goggles:

Goggles are used to protect the eyes from glare of weld ing. Ultra violet rays and infra-

red light rays may cause serious damage to the eyesight so every possible precaution should

be taken to shield the eyes from them. Hand shield or head shield may be used to protect the

eyes.

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ix. Apron:

Protective clothings such as apron should be used to protect from the spattering particles

of molten flux and the welded material.

3.5.3 Comparison between ac and dc arc welding:

The comparison between AC and DC arc welding systems is given in Table

AC welding DC welding

Stability of arc Fluctuating arc/arc instability

Faster welding operation Slow welding operation

Occupies less space Needs more space

AC power supply is easily available DC power supply needs transformer rectifier

unit

Arc blow is minimized Presence of significant arc blow

Starting arc is difficult Easy to start the arc

Low cost of operation High cost of operation

Salient features of ARC Welding:

The Equipment is relatively easy to use and inexpensive.

The equipment is portable and ideal for confined spaces.

Auxiliary gas shielding is not required. Arc welding is suitable for most commonly used metals and alloys.


To know about arc welding and its types, Arc welding equipments ,Comparison of

AC and DC arc welding. To undersand Salient features of Arc welding and Other welding

processes.

Questions

1. Explain arc-welding process with neat sketch

2. Compare arc welding and gas welding process. 3. What are the different arc welding methods?

4. Why slag is formed in arc welding process.

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STUDY MATERIAL




Lesson No: <6> Module / Unit No:

No. of Lecture Hours: <8>

<3>

Title: <METAL JOINING PROCESS-BRAZING AND SOLDERING>


< To gain knowledge about brazing, soldering processes and adhesives >

Methodology:

0 – 10 Minutes : Brief about brazing

11 – 20 Minutes : Brief about soldering

21 – 30 Minutes : Role of cleaning in brazing and soldering

30 –45 Minutes : Flux for brazing and soldering and its role


Brief Content:

Brazing

Soldering

Role of cleaning

Flux for brazing

Flux for soldering

Role of flux

Detailed Content:

This part contains the detailed notes of Brazing, Soldering and the flux used.

3.6.1 Brazing

In brazing, the filler material is a metal with Tm lower than that of the metals being joint. The filler is

placed in the joint (or near it), and the metals are heated till the filler melts (but not the components). The

melted filler material fills the joint and, on cooling, creates a brazed joint. In some cases, oxy-acetylene gas

welding may be used for this process, with the filler made of a low Tm metal rod. Fluxes are used in

brazing, for the same reasons as in welding. In some cases, capillary forces cause the

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brazing material to flow evenly into the joining interface (see example below).

Figure 8. (a) Brazing (b) Furnace brazing

3.6.2 Soldering

Solder is a very low Tm metal alloy (Lead + Tin), melting at around 200°C. This is very useful to

create joints in electronic circuits, which need not withstand large forces, but should be made with

low energy, low temperature processes.

3.6.3 Preparatory cleaning for brazing and soldering:

All oil, grease, paint, residual cutting lubricants, atmospheric dirt, oxide and rust films

must be removed for effective wetting. This is achieved by either mechanical or chemical

means.

Mechanical cleaning involves shot blasting (which is better than sand), grinding,

sanding, filing etc. Oily or greasy surfaces should be degreased before mechanical cleaning.

Chemical cleaning includes degreasing in solvents of the trichlorethylene type (vapour or

liquid) or hot alkali type such as trisodium phosphate used hot. The cleaning solution must be

thoroughly washed off by soft water or steam. Removal of scale, oxides etc. by chemical

methods involves acid cleaning, usually by hydrochloric and sulphuric acid, followed by hot

water washing and immediate drying.

3.6.4 Fluxes for brazing and soldering

Flux for brazing:

The flux will be in the form of paste or liquid solution for easy application. Borax and

Boric acid are common fluxes for brazing with Cu fillers.

Flux for soldering:

The fluxes used in soldering are ammonium chloride, Zinc chloride, rosin, rosin

dissolved in alcohol. They are classified as Inorganic fluxes (very active), organic fluxes

(active) and rosin fluxes (less active).

Role of flux in brazing and solde ring:

For effective capillary action and for uniform distribution of the filler metal the

surfaces has to be clean which is accomplished by the flux.

To remove surface contaminants.

To remove oxides present on the surface.

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To remove oil or grease present at the surface. For fluidity of the filler metal.

To avoid oxidation of the molten filler metal.

To avoid oxidation of base metal due to the heating.

Expected Learning outcome To learn about the process of Brazing and Soldering. And understand the Role of

cleaning, role of Flux for brazing and soldering.

Ques tions 1. Define soldering. 2. What are the applications of soldering process? 3. How does a ―FLUX‖ help in soldering process? 4. Define brazing.

5. Give some applications of brazing process. 6. What are the major types of brazing process?

7.. Name some important Fluxing agents. 8. Write short notes on following with sketch. a. Soldering b. Brazing

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STUDY MATERIAL






<3>

Title: <METAL MACHINING PROCESS PROCESS-LATHE >


< To gain knowledge about lathe and its types, Operation of lathe >

Methodology:

0 – 5 Minutes : Introduction to lathe

6 – 20 Minutes : Types of lathe

21 – 30 Minutes : Components of lathe

31 –45 Minutes : Lathe Operations


Brief Content:

Lathe and its types

Main components of lathe

Lathe Operations

Detailed Content:

This part contains the detailed notes of types, components and operations of Lathe.

3.7.1 Types of lathes

A lathe machine is used for the shaping and machining of various work pieces. There are

many different types depending on the material you are working on.

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In manufacturing, it is important to produce work pieces according to specifications.

This is where the lathe machine comes in handy. A lathe machine is used for the machining

and working of hard materials. Conventionally, the lathe machine is designed for the

machining of metals, but as new materials emerged, there are lathe machines that are used for

these materials as well. The main function of the lathe is to remove material from a work

piece through the use of cutting tools. The lathe shapes a material by holding and rotating the

material as a cutting tool is advanced into it. There are a lot of shapes and forms that can be

produced by the lathe machine. More importantly, these shapes come in various sizes and

specifications.

Generally, the lathe is composed of the bed, headstock, tailstock, and the carriage.

The bed allows the carriage and the tailstock to be in parallel with the axis of the spindle.

Moreover, the bed also serves as the base of the lathe and is connected to the headstock. The

headstock basically is where the main spindle, the change gears, and the speed change

mechanism are mounted on. On the other hand, the tailstock is directly mounted on the

spindle axis, and serves as the tool holder. The tailstock is mounted opposite the headstock.

Finally, the carriage is where the tool bit or the drill bit is placed and holds it in position as it

moves perpendicularly or longitudinally. The direction of the movement of the cutting tool is

actually controlled by the operator.

There are three general types of lathe machines which are engine lathes, turret lathes,

and special purpose lathes. Each of these lathes has specific applications and distinctive

characteristics.

Engine lathes. These are probably the most popular among the lathe machines. In fact, no

machine shop is seen without this type of lathe. The good thing about engine lathes is that it

can be used in various materials, aside from metal. Moreover, the set-up of these machines is

so simple that they are easier to use. Its main components include the bed, headstock, and

tailstock. These engine lathes can be adjusted to variable speeds for the accommodation of a

wide scope of work. In addition, these lathes come in various sizes.

Turret Lathes. These types of lathes are used for machining single workpieces sequentially.

This means that several operations are needed to be performed on a single work piece. With

the turret lathes, sequential operations can be done on the work piece, eliminating errors in

work alignment. With this set- up, machining is done more efficiently. Correspondingly, time

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is saved because there is no need to remove and transfer the work piece to another machine

anymore.

Special Purpose Lathes. As the name implies, these lathes are used for special purposes such

as heavy-duty production of identical parts. In addition, these lathes also perform specific

functions that cannot be performed by the standard lathes. Some examples of special purpose

lathes include the bench-type jewelers’ lathes, automatic lathes, crankshaft lathes, duplicating

lathes, multispindle lathes, brakedrum lathes, and production lathes among others.

Swiss Type Automatic Lathe

Duplicating Lathe

3.7.2 Basic Components of a Lathe:

The basic components of the lathe are shown in Figure.

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The lathe machine is an assembly of sub-assemblies and components. The important

parts and sub-assemblies are: (a) The bed (b) The headstock assembly (c) The tailstock

assembly (d) The carriage assembly (e) The quick-change gearbox.

a. The Bed:

This is a rigid frame made of grey cast iron, on which all the sub-assemblies and parts

of lathe are mounted. On its upper surface it has two pairs of guide-ways, one is a pair of

inverted V-guides, and other is a pair of flat-guides. The V- guideways are for the carriage,

and the flat guideways are for the tailstock. The guideways are machined with high precision,

and their surface is hardened.

b. The Headstock Assembly:

The headstock has all the gear arrangements for transfer-ring the power from the

electric motor to the chuck and live centre. The headstock has a cast iron housing, mounted

on the inner guideways at one end of the bed. It has a hollow spindle which is mounted on

taper roller bearings. The headstock has a gear-box by which different rotational speed of

work piece can be obtained. The number of speeds varies between 8 to 18 and the speed

range is between 40 to 2500 RPM. The speeds are available in geometric progression. One

end of the spindle projects out of the headstock housing, and different types of work-holding

devices (chuck, dog plate, and face plate) can be mounted on it.

c. The Tailstock Assembly:

The tailstock assembly is mounted at the end of the bed, opposite to the headstock.

The tailstock assembly has a hollow steel tube called barrel, which can be moved in and out

of the tailstock housing, by a hand-wheel and screw arrangement. It can also be moved

horizontally and perpendicular to the axis of the bed. The ram can hold a dead centre for

supporting a long work-piece. It can also hold a tool (like a drill-bit, reamer, or a boring tool).

The tailstock assembly is mounted on the inner guideways, and it can be slided over them.

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d. The Carriage Assembly:

The carriage can be moved along the bed by means of a handwheel. It consists of a

saddle, a cross-slide, a compound slide, a tool post and an apron. The function of the carriage

and its components is to hold the tool and move it in different manners.

The saddle is an H-shaped casting which moves along the bed on the outer guideways.

The cross slide is mounted on the saddle.

The cross slide can be moved horizontally and perpendicular to the bed. This motion is

given by means of a screw and hand-wheel mounted on the saddle, and a nut mounted on the

cross slide, which is engaged with the screw. A graduated circular scale is also attached with

the hand-wheel. The compound slide is mounted on the cross slide.

The compound slide can be rotated about a vertical axis. It can also be moved along its

longitudinal axis by a screw and hand-wheel arrangement. The compound slide is used for

taper turning.

The tool post is mounted on the compound slide. The cutting tool is mounted on the tool

post, by means of bolts.

The apron is attached to the front part of the carriage assembly. It carries a hand-wheel to

move the carriage along the bed. This motion is achieved by means of a rack and pinion

arrangement. The rack is supported on the bed, and runs along the entire length of the bed.

The pinion is mounted on the shaft of hand-wheel of the carriage. The apron also carries gear

mechanism for giving powered motion to the carriage by means of a lead-screw.

3.7.3 LATHE OPERATIONS Facing off

Parallel Turning

Parallel Turning

Parallel Turning

The tool moved parallel to the work and cylindrical shapes are formed

Also known as sliding

Parallel Turning

Facing off

The tool is moved at right angles to the work using the cross slide

Flat surfaces are produced

Knurling

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A knurling tool is used to press a pattern onto a round section.

The pattern is normally used as a grip for a handle.

This provide a grip for the round part

Knurling

Parting off

If the student wants to cut off the part they have turned, they can use the hacksaw and a vice or use the parting off tool on the lathe.

Setting the tool height

The cutting tool on the lathe must be set to the exact centre of the work-piece

We use the centre of the tailstock to guide us to the correct height

Screw-cutting on the lathe

Lathes are also used to cut threads in round bars

These threads take up different profiles e.g is (60°) ACME etc.

These threads can be seen on bench vices, lathes etc.

Operations of Lathe Machine:

(i) Facing: This operation is almost essential for all works. In this operatio n, as shown in

fig., the work piece is held in the chuck and the facing tool is fed from the center of the work

piece towards the outer surface or from the outer surface to the center, with the help of a

cross-slide.

(ii) Plane Turning: It is an operation of removing excess amount of material from the surface

the surface of the cylinder work piece. In this operation, shown in fig., the work is held

either in the chuck or between centers & the longitudinal feed is given to the tool either by

hand or power.

(iii) Step Turning: It is an operation of producing various steps of different diameters of

in the work piece as shown in fig. This operation is carried out in the similar way as plain

turning.

(iv) Drilling : It is an operation of making a hole in a work piece with the help of a drill. In

this case as shown in fig., the work piece, by rotating the tail stock hand wheel. The drill is

fed normally, into the rotating work piece, by rotating the tail stock hand wheel.

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(v) Reaming : It is an operation of finishing the previously drilled hole. In the operation as

shown in fig., a reamer is held in the tailstock and it is fed into the hole in the similar way

as for drilling.


To know about the Lathe and its types, Main components of lathe and different types

of Lathe Operations.

Questions

1. What are the principal parts of a lathe?

2. Name the various parts of center lathe. 3. What is the purpose of tailstock?

4. What are parts provided in the carriage? 5.. List various types of lathe. 6. Write the specification of a central lathe. 7. Name the various operations performed in a lathe. 8. Draw the neat sketch and explain the construction of center lathe. 9. Describe the various types of lathe in the engineering field.

10. Describe the following terms, a. Carriage, b. Live center c. Dead center with neat sketches

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STUDY MATERIAL






<3>

Title: <METAL MACHINING PROCESS-DRILLING MACHINES>


< To gain knowledge about drilling process and its types>

Methodology:

0 – 10 Minutes : Drilling and its purpose

11 – 35 Minutes : Types of drilling machine

36 – 45 Minutes : Components of drilling machine


Brief Content:

Drilling machine

Purpose of drilling

Types of drilling machine

Components of drilling machine

Detailed Content:

This part contains the detailed notes of drilling machine and operations.

3.8.1 Drilling:

Drilling is the operation of producing circular hole in the work-piece by using a rotating

cutter called DRILL.

The machine used for drilling is called drilling machine.

The drilling operation can also be accomplished in lathe, in which the drill is held in

tailstock and the work is held by the chuck.

The most common drill used is the twist drill.

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3.8.2 Drilling Machines:

It is the simplest and accurate machine used in production shop.

The work piece is held stationary i.e. clamped in position and the drill rotates to make

a hole.

Types of drilling machine:

1. Based on construction: a. Portable drilling machine, b. Sensitive drilling machine, c. Radial drilling machine, d. Up-right drilling machine, e. Gang drilling machine, f. Multi-spindle drilling machine

2. Based on Feed: a. Hand driven b. Power driven

Sensitive or Bench Drilling Machine:

This type of drill machine is used for very light works. Fig.1 illustrates the sketch of

sensitive drilling machine.

The vertical column carries a swiveling table the height of which can be adjusted

according to the work piece height.

The table can also be swung to any desired position.

At the top of the column there are two pulleys connected by a belt, one pulley is

mounted on the motor shaft and other on the machine spindle.

Vertical movement to the spindle is given by the feed handle by the

operator. Operator senses the cutting action so sensitive drilling machine.

Drill holes from 1.5 to 15mm.

Fig.1. Sensitive Drilling Machine

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Up-Right Drilling Machine:

These are medium heavy duty machines.

It specifically differs from sensitive drill in its weight, rigidity, application of power

feed and wider range of spindle speed. Fig.2 shows the line sketch of up-right drilling

machine.

This machine usually has a gear driven mechanism for different spindle speed and an

automatic or power feed device.

Table can move vertically and

radially. Drill holes up to 50mm

Fig.2 Up-Right Drilling Machine

Radial Drilling Machine:

It the largest and most versatile used for drilling medium to large and heavy work

pieces.

Radial drilling machine belong to power feed type.

The column and radial drilling machine supports the radial arm, drill head and motor.

Fig.3 shows the line sketch of radial drilling machine.

The radial arm slides up and down on the column with the help of elevating screw

provided on the side of the column, which is driven by a motor.

The drill head is mounted on the radial arm and moves on the guide ways provided

the radial arm can also be swiveled around the column.

The drill head is equipped with a separate motor to drive the spindle, which carries

the drill bit. A drill head may be moved on the arm manually or by power.

Feed can be either manual or automatic with reversal mechanism.

Salient features,

Three movements are

possible Versatile

When the work is very large, the base can be used for holding it.

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Fig. 3 Radial Drilling Machine

3.8.3 Components of drilling machine:

Spindle:

The spindle holds the drill or cutting tools and revolves in a fixed position in a sleeve.

Sleeve:

The sleeve or quill assembly does not revolve but may slide in its bearing in a

direction parallel to its axis. When the sleeve carrying the spindle with a cutting tool is

lowered, the cutting tool is fed into the work: and when it’s moved upward, the cutting tool is

withdrawn from the work. Feed pressure applied to the sleeve by hand or power causes the

revolving drill to cut its way into the work a fraction of an mm per revolution.

Column:

The column is cylindrical in shape and built rugged and solid. The column supports

the head and the sleeve or quill assembly.

Head:

The head of the drilling machine is composed of the sleeve, a spindle, an electric

motor and feed mechanism. The head is bolted to the column.

Worktable:

The worktable is supported on an arm mounted to the column. The worktable can be

adjusted vertically to accommodate different heights of work or it can be swung completely

out of the way. It may be tilted up to 90 degree in either direction, to allow long pieces to be

end or angle drilled.

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Base:

The base of the drilling machine supports the entire machine and when bolted to the

floor, provides for vibration-free operation and best machining accuracy. The top of the base

is similar to the worktable and may be equipped with t- slot for mounting work too larger for

the table.

Hand Feed:

The hand feed drilling machines are the simplest and most common type of drilling

machines in use today. These are light duty machine that are operated by the operator, using a

feed handled, so that the operator is able to ―feel‖ the action of the cutting tool as it cuts

through the work piece. These drilling machines can be bench or floor mounted.

Powe r feed:

The power feed drilling machine are usually larger and heavier than the hand feed

ones they are equipped with the ability to feed the cutting tool in to the work automatically, at

preset depth of cut per revolution of the spindle these machines are used in ma intenance for

medium duty work or the work that uses large drills that require power feed larger work

pieces are usually clamped directly to the table or base using t –bolts and clamps by a small

work places are held in a vise. A depth –stop mechanism is located on the head, near the

spindle, to aid in drilling to a precise depth.

3.8.4 Drill Materials:

The two most common types are

1. HSS drill

2. Carbide- tipped drills


To know about the Drilling machines, Purpose of drilling, Types of drilling machines and

Components of drilling machines.

Questions

1. What does drilling mean. 2. Name some types of drilling machine. 3. What are the main parts of a drilling machine? 4. What is the major feature of radial drilling machine over the other? 5. Name the various drilling operations. 6. What is reaming. 7. Define boring operation 8. List the types of drilling machine. 9. Define drilling? What are the various kinds of drilling machines available? 10. Explain any two of the drilling machines with neat sketches. 11. Explain the various kinds of drilling machine operation with neat sketches?

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