1. LEARNING EXPERIENCE – I
Competence:
Set Electrical Welding Plant ready for operation by following proper safety
Precautions.
Enabling objectives:
After undergoing the learning experiences in this module you should be able to :
Set up arc welding equipment for different operations.
Select current and voltage rating for a job.
Test the setup
Observe safety precautions.
Learning Activities:
Read information sheet.
Complete assignment given in assignment sheet.
Complete the practice exercises and check answers.
Get the results checked before proceeding to Learning Experience II.

2. Element: Set up Arc Welding equipment.
Information Sheet
In various situations you are required to make different shapes with metal components to serve the
purpose. Therefore you need to learn the technique to join metals.
Metal Joining Methods: There are three basic types of joining methods.
1) Flexible Joint: This is the simplest process
of metal joining in which components can be
joined and dis-assembled as and when
required without any destruction.
Example: Bolting
2) Semi-permanent joint: This is the process
of joining in which components can be dis-
assembled when required with minor destruction
of joining component.
Example: Folding, Riveting
3) Permanent Joint: This is the process of
joining in which component cannot be
disassembled without destruction.
Example: Welding, Soldering
In this module our focus is only on Welding.
Welding is a process of joining metal with the
application of heat.
Welding is applicable to joining of same metal
components.

3. Applications of Welding: You can see
application of welding in various fields like
1) Furniture making
2) Bridge Construction
3) Building construction
4) Doors and window making etc.
We shall discuss the process of manual metal
arc welding.
Welding is a process of joining metal with the
application of heat.
Welding is applicable to joining of same metal
only.
Electrical Welding is a fusion welding process.
In this process electricity is used to develop heat
of fusion.
Let’s understand term fusion in following steps:
- It is the process of surface heating up to
melting point.
- Melted joining boundaries become fluid and mix
Burning gas together.
- Filler rod provides additional material during
fusion.
- Homogeneous bond is formed when the metal
cools from liquid to solid state.
Lets learn basics of electricity prior to entering into the subject.

4. Electric Current : Flow of electricity is called as current. Current is measured in “Ampere”.
Types of electric current : There are two types of electric current.
1) Alternating Current (AC) : This is the current which changes its direction and amplitude.
Example: Electrical supply in our home.
2) Direct Current (DC) : This is the current which flows in one direction.
Example: Car battery
Voltage : This is the pressure which causes current to flow. Voltage is measured in ‘Volts’.
Conductor: Substance which allow to electricity to flow through it is known as conductor.
Example : Copper, Iron , Aluminium etc.
Insulator : Substance which do not allow current pass through it is known as insulator.
Example: Wood, Cotton, Rubber etc.
Principle of arc welding
When electric current flows through a conductor,
conductor property restricts this flow. The
restriction in flow of electrical energy results in
development of heat. Eg. Water heater used at
our home.
Amount of heat developed depends upon factors
1) Current (I)
2) Resistance of conductor (R)
3) Time of current flow (T)
Mathematical relation is as follows:
H = I2 RT

5. Applications
1) Day to day fabrication work
2) Maintenance & repair work
3) Vessel fabrication
4) Piping work
5) Building & bridge construction etc
Types
Various types of arc welding methods have been developed like:
Manual Metal Arc Welding
Carbon arc welding
Atomic hydrogen arc welding
Tungsten inert gas arc welding
Submerged arc welding
Electro-slag arc welding
Plasma arc welding
Except manual metal arc welding rest of the methods are beyond the scope of this training.
Advantages
1) This is the simplest of arc welding processes.
2) Equipment are portable and the cost is low.
3) Process has vast application as variety of electrodes are available.
4) A wide range of metal & alloys can be welded by this process
5) Highest weld quality can be achieved in any position.
Limitations
1) Mechanizations is difficult
2) Best suitable for short weld length
3) Process is slow
4) Skill is required to produce quality welding joints.

6. Welding machine: Welding machine is basically
a rectifier which converts AC mains supply in to
DC supply.
Welding accessories: During operation apart from welding machine you need several small
equipments or components as follows.
1) Electrode Holder: This is device, which
you use to grip an electrode during
welding. Connect electrode holder to the
welding machine through an electric cable.
You have to always ensure that the holder
grip is insulated for safety reasons.
2) Earth clamp: This is a device, which is
used for connecting job or worktable to the
earth cable.

7. 3) Welding cable: You require welding cable
for current flow from welding machine to
electrode welding cables carry heavy
current so you must be careful about
- Proper size of cable
- Tight cable connection
- Good insulation
4) Welding screen: This is a device, which
protects your eyes and face from spark
and radiations. Different shades of colors
are used in welding screen. You have to
select correct shade with respect to
welding current as shown in the table.
Practice 1: Assemble electrical welding machine and accessories and test the setup.
Current and voltage setting: You may have to join different pieces in the real work situation.
Different current or voltage settings are required for the different jobs. To set current adjust knob
provided to the required value. You will learn current requirement in the next element.

8. Testing of setup:
1. Ensure that you have taken precaution against
electrical shock.
2. Switch on the main switch
- You will observe that the main line signal on
machine starts glowing, at the same time
voltmeter also shows the supply voltage.
- You can listen to a humming sound from
machine.
3. Grip electrode in the holder

9. 4. Rub or touch electrode on metal piece
5. If arc generates, it shows that machine is
ready for welding.
Safety Precautions: You must take following precautions while working with electrical welding
equipment.
1) Wear your safety clothing and chipping goggles.
2) Keep other devices ready, like welding screen, holding tools etc.
3) Ensure you are wearing shockproof gloves and shoes.
4) Get main supply connection done through skilled electrician
5) Ensure that electrical joints are proper.
6) Check by yourself that the cable and electrode holder are not damaged.
7) Do not allow unwanted persons in the working area.
8) Check by yourself the operation of main switch, current setting knob and earth clamp.

10. Common tools: During operation you will also need some other tools for holding, cutting and
marking purpose.
Steel Rule: This is a tool that you can use to
measure length and marking points. It contains
graduations in mm, cm and inch.
Precautions:
1. Save edges and corners from wear & tear.
2. Do not use in place of screw driver.
Try square: This is a tool used to check rightness
(90° angle) of the edges. Set base along one of
the edge and check gap along other edge
opposite to light source. If you cannot see light,
means edges are at right angles.
Precautions: Do not use as hammer or
screwdriver.
Center Punch: This is a tool used for marking
points on the sheets. Centre punch is used for
marking centers for radius and marking points on
a job.

11. Scriber : This tool consists of sharp points as
shown in figure. Scriber is used to mark lines on a
job by scratching.
Precautions:
1. Do not use as center punch.
2. Save points from damages.
Compass : This tool consists of two pivoted legs
with sharp points. Compass is used to mark
circles and arcs. To mark arc or circle place one
of the leg on center point marked with center
punch. Set other leg so that point-to-point
distance is equal to the radius of the curve with
steel rule. Hold grip handle and rotate about the
center.
Hammer: This is a commonly used tool. Hammer
is used to blow impact. Different types of
hammers are available according to purpose of
use.
Chisel: This is tool used for cutting metal pieces
and removing welds.

12. Tong: This a tool used to hold hot pieces.
Hacksaw: This a tool used to cut metal along
straight line. It consists of frame and blade. Blade
can be replaced whenever required. In case of
hacksaw blade, tension is very important,
improper tension causes damage to the blade. To
check tension tap blade with finger, ringing sound
indicates proper tension.
File: This is a tool used for finishing and removing
burrs. Files are available in different shapes and
roughness. Bastard file, rough files and fine files
are used for heavy, medium and fine cuts
respectively.
Chipping hammer: This is the tool, which helps
you to remove slag from the weld.
Wire brush: This is a device, which you need for
cleaning of job before welding operation.

13. Self Test
Answer the following.
Q1. What is the source of heat of fusion in Q5. Write two limitations of electrical welding.
electrical welding?
Q2. What is the unit of current? Q6. What is the purpose of electrode holder?
Q3. Write two applications of electrical welding. Q7. List two safety precautions.
Q4. Write two advantages of electrical welding. Q8. What is the function of chipping hammer?
Write True (T) or False (F):
1) AC current flows only in one direction.
2) Ampere is the unit of voltage.
3) Insulator does not allow current to flow through it.
4) Welding machine converts AC current to DC current.
5) Chipping hammer is used to remove weld.

14. Solution to Self test
A1. Electricity is the source of heat of fusion in A5. The two limitations are
electrical welding. 1) Mechanizations is difficult.
2) Best suitable for short weld length.
A2. The Unit of current of current is Ampere. A6. This is device, which you use to grip an
electrode during welding.
A3. The two applications are A7. Two safety precautions are as follows
1) Furniture making
2) Bridge Construction. 1) Wear safety clothing and chipping goggles.
2) Ensure you are wearing shockproof gloves and
shoes.
A4. The two advantages are A8. This is the tool, which helps you to remove
1) This is the simplest of arc welding slag from the weld.
processes.
2) Equipment is portable and the cost is low.
True and False:
1) False
2) False
3) True
4) True
5) True

15. LEARNING EXPERIENCE – II
Competence :
Fabricate articles using electrical welding techniques.
Enabling objectives :
After undergoing learning experiences you should be able to :
Perform pre-welding operations.
Select equipment and accessories
Select appropriate voltage and current setting for a job.
Fabricate articles using arc-welding equipment.
Perform post weld operations.
Learning Activities :
Read information sheet.
Complete assignment given in assignment sheet.
Complete the practice exercises and check answers.
Get the results checked before completion of the module.
Element: Fabricate different articles using Electrical welding equipment

16. Information sheet
In the last element you learnt about the setup and general information. To use electrical welding
machine to fabricate an article you should know :
- How welding takes place.
- What is the procedure?
- How to select correct electrode.
- How to prepare an edge.
- What are the common defects?
As you already know in the arc welding heat
of fusion is produce by electrical energy.
When you perform arc welding you will have
to make arrangements as shown in the figure
First you have to generate the arc by bringing
electrode near the job. When there is small air
gap between electrode and the job, arc is
generated. The arc causes heating of job
boundaries to molten state at the same time
melt the electrode. When this molten filler
material deposits on job it causes a
homogenous bond.
How to produce an arc:
Before starting welding operation you should

17. Clean the work piece mechanically or
chemically to remove rust, oil and grease etc.
This ensures proper bonding of metal during
welding.
Set the work piece on worktable in flat position.
Wear your safety clothes and devices.
Check machine for proper connections and damaged cables
Select suitable welding electrode as per the table and fix to the electrode holder.
Switch on the welding machine
Set current and voltage ratio.
Strike an arc. You can strike arc in two ways:
By Scratch:
Keep welding screen in front of your eyes.
Bring electrode near the job, so that electrode
is at an angle of 750-800 with the job surface
and tip is about 2-3 cm above the surface.
Twist your wrist quickly. While doing so,
electrode scratches the job. This action
generates an arc.
You should see this arc through the welding
screen and maintain a gap equal to the dia of
rod.

18. By tap:
- Touch electrode to the job.
- Lift the electrode slowly; this action will
generate an arc.
- Maintain the arc.
- If electrode sticks to the job you should
remove it quickly from the job to prevent
overheating just twist you wrist to
withdraw it.
How to produce a welding bead:
- Generate arc.
- Maintain electrode angle 900 with
0
surface and 70 with line of weld.
- Move electrode vertically down
smoothly so that arc is maintained.
- Withdraw electrode quickly at the end
of welding.
To perform correct welding selection of correct electrode is essential, so lets learn about the
electrodes.
While performing arc welding you need an electrode. It basically serves two purposes.
1) It completes welding circuit.
2) It provides additional material during fusion.
An electrode is made of metallic wire of standard dia and length. This wire is coated with a
material known as flux but sometimes not.
Various types of electrodes are available in the market, therefore electrodes are classified in
different categories.

19. Classification is based upon
1) Method of coating
2) Coating factor
3) Type of flux coating
4) Core wire material
Coating factor: This is the ratio of coating dia to the core wire dia.
Coating dia
Coating factor = ---------------------------
Core wire dia
1) If ratio is 1.25 to 1.3 electrode is light
coated.
2) If ratio is 1.4 to 1.5 electrodes is
medium coated.
3) If ratio is 1.6 to 2.2 electrodes is heavy
coated.
Function of flux: During welding flux performs following functions
1) It stabilizes the arc.
2) It protects molten metal from oxidation.
It compensates loss of elements burnt.
Types of flux
1) Cellulose Flux: This flux contains cellulose. These types of flux give deep penetration
and form very less slag during welding.
2) Rutile flux : This flux contains silicate and some part of cellulose. These fluxes are
used for wider gap filling.
3) Iron oxide flux: This flux contains iron oxide and silicates.
4) Basic flux : This flux contains fluoride and calcium carbonate. Basic flux form
large pool of molten metal and slag.
Codification of Arc Welding Electrodes
Necessity of coding: As you know various types of electrodes are available for different purposes.

20. It is necessary for you to identify suitable electrode for your purpose. You can chose appropriate
electrode only if you can understand special number i. e. code of an electrode.
Electrode coding mainly consists of:
1) Prefix E to indicate coated electrode for manual metal arc welding.
2) Type of flux
A – Acid, B – Basic ,C – Cellulose, R – Rutile , S – Others
3) Mechanical properties: These are the
Code Ultimate Yield properties of weld in terms of strength. Refer
Tensile Strength Strength (min)
N/mm2 N/mm2 table, You can find that code no 4 corresponds
4 410-510 330 to Ultimate tensile strength in the limit of 410-
5 510-610 360
510 N/mm2 while Min yield strength to 330
N/mm2
Code Welding position
4) Welding position: Refer corresponding
1 All table code 2 indicates that welding rod is
2 All except vertical
3 Flat butt, flat fillet unsuitable for vertical position otherwise can be
4 Flat butt, flat fillet used for all other welding positions.
5 Vertical down
6 Any other
5) Welding voltage : Refer the table , code 3
Code Polarity in Open circuit
indicates that 70 volts Ac is necessary to use
DC welding Voltage in AC
Welding this electrode.
0 - Ve -
1 +Ve/-V e 50
2 -Ve 50
3 +Ve 50
4 +Ve/-Ve 70
5 -Ve 70
6 +Ve 70
7 +Ve/-Ve 90
8 -Ve 90
Thus a code ER 4211 represents
Manual metal arc electrode covered with rutile coating, having ultimate 410-510 N/m2, yield strength
330 N/mm2 elongation 22%, can be used for all welding position, voltage required 50V.
Arc Length: When you produce an arc, the distance between electrode and the job is called as arc

21. length
Short Arc: If you maintain distance between
electrode and job less than the dia of electrode,
the arc produced is short arc.
Characteristics
1) You can hear popping sound.
2) You can observe rapid filler rod
consumption
3) You can observe convex weld bead
formation.
4) You can observe more fusion and
penetration.
5) You can see less spatters
You can see irregular ripples
Long Arc: If you maintain the distance between
electrode and job more than the dia of filler rod
while welding, the arc produced is long arc.
Characteristics
1) You can hear humming sound
2) You can observe un-stability of arc
3) You can see more spatters
4) You can observe poor fusion &
penetration
5) You can see wide and coarse ripple.
Normal Arc: If you maintain the gap between
job and electrode equal to the dia of electrode,
the arc produced is normal arc.
Characteristics
1) You hear cracking sound
2) You can see less spatters
3) You can observe correct fusion &
penetration

22. 4) You can see proper shaped weld bead.
Welding Joints & Positions
Type of welding joint refers to the shape formed
by placement of joining edges. There are 5
basic types of joints.
1) Butt joint
2) Corner joint
3) Edge joint
4) Lap joint
5) Tee joint
Flat Position: In this position nozzle points
towards the ground. Nozzle is moved in any
direction.
Horizontal Position: In this position nozzle
points towards vertical plane opposite to your
body but moves only left to right or right to left.

23. Vertical Position: In this position nozzle points
towards vertical plane opposite to your body but
moves only up and down.
Overhead Position: In this position nozzle
points towards the plane above your head.
Nozzle can be moved in any direction.

24. Types of weld
Weld type refers to the ways of depositing metal on joining pieces. There are 4 basic types of welds
as follows
Bead weld: This type of weld is formed
when one or more weave beads are
deposited on unbroken surface. The
purpose of this weld is to obtain desired
property or dimension.
Application: This type of weld is used for
strengthening the metal sheet, repair of worn
out shafts etc.
Butt weld: Butt weld is formed when the metal to be deposited penetrates the cavity formed by
pieces to be joined which are in same plane.
Application: This type of weld is used to join pieces, which are in same plane e.g. Pipe joints.
Fillet weld: Fillet weld is formed when metal is deposited at the line of interface for joining
Application: This weld is used for joining pieces, which are not in the same place.
Butt weld: Butt weld is formed when the metal
to be deposited penetrates the cavity form by
pieces to be joined which are in same plane.
Application: This type of weld is used to join
pieces, which are in same plane e.g. Pipe
joints.

25. Fillet weld: Fillet weld is formed when metal is
deposited at the line of interface for joining.
Application: This weld is used for joining
pieces, which are not in the same place.
Other terms related to weld
Leg Length: The distance between points
where two ends of weld deposit touches the
plate being joined on either side of a tee joint
and point of joint.
Reinforcement : Excess metal deposited over
the surface of parent metal.

26. Root: The distance between parts to be
joined. This distance is filled by weldment.
Root face: Face below the chamfered
surface.
Root run: The first run of weld deposited over
the joint.
Sealing run: Small weld deposited at one side
for sealing purpose.

27. Common welding defects
Undercut: Groove formed in the parent metal.
Cause Remedy
Current too high Adjust
Welding speed fast Adjust
Faulty electrode Correct
manipulation
Wrong electrode angle Correct
Overheating of job Correct arc length
.
Overlap : Molten metal flows over parent
metal.
Cause Remedy
Low current Adjust
Slow welding speed Adjust
Long arc Adjust
Large dia electrode Use correct dia
Porosity : Holes or lack of material in weld.
Cause:
1.Presence of contamination like moisture.
2. Fast cooling of weld metal
3. Improper cleaning of edges.
Remedy:
1. Remove oil , grease , and moisture during
pre welding operations.
2. Use good quality of flux.
3. Avoid long arc.

28. Spatter : Small droplet deposition around
welding line.
Cause Remedy
High welding current Adjust
Long arc Correct
Poor electrode quality Replace
Melting of edges: Parent metal melts at
edges.
Cause Remedy
Oversize electrode. Replace
High welding current Adjust
Wrong electrode Correct
manipulation
Crack: Hairline separation of metal in the
weldment.
Cause Remedy
Fast cooling Correct
Pre-stressed metal Relieve stresses
More passes run Reduces passes run
Incomplete penetration: Failure of molten
metal to reach up to root.
Cause Remedy
Lesser bevel angle Correct
Low current Adjust
Large dia electrode Replace

29. Slag Inclusion: Entrapped foreign material.
Cause Remedy
Incorrect edge Correct
preparation
Wrong electrode Replace
High current Adjust
Long arc Adjust
Assignment I
Join given pieces using square butt joint in flat position.
You are provided with: 3. Tack weld on both ends as well as
center with 3.15 mm electrode and
1. Safety devices.
130 Amp.
2. Electrical welding equipment
4. Deposit one side single run with
3. Welding accessories.
3.15 mm welding rod and 110 Amp.
4. Piece of M S plate.
Maintain electrode 90o with surface
Procedure:
and 80o with line of weld.
1) Clean surfaces and prepare square
5. Move electrode forward steadily.
edges.
2) Take safety precautions. 6. Remove slag from weld and inspect.
3) Set pieces as butt joint with root gap
1.5 mm.

30. Material Name:
Size Instructor’s Signature:
Scale
Assignment 2
Join given pieces using fillet and lap joint.
You are provided with:
5. Deposit root run with 3.15 mm
1. Safety devices.
electrode and 130 Amp current..
2. Electrical welding equipment
3. Welding accessories. 6. Maintain electrode angle 45o with
4. Pieces of MS plate. surfaces and 80o with line of weld.
Procedure: 7. Remove slag and clean..
8. Deposit covering run with weaving
1. Take safety precautions.
motion, with 4 mm electrode and
2. Clean surfaces and square the edges.
170 Amp current.
3. Set the pieces in the form of lap joint as
9. Prevent edges from melting.
shown.
4. Set job in flat position and tack the pieces 10. Remove slag, clean and inspect for
at the ends and center. defects.

31. Material Name
Size Instructor’s Signature
Scale
Assignment 3
Join given pieces using fillet weld and corner joint in flat position
You are provided with:
8. Set current 125 Amp and deposit root
1. Safety devices.
run to obtain complete penetration.
2. Electrical welding equipment
9. Remove slag and inspect for defects.
3. Welding accessories.
10. Select 4 mm electrode and set current
4. Pieces of MS plate.
to 170 Amp. Deposit intermediate run
Procedure:
1. Clean edges and surfaces. with slight weaving.
2. Take safety precautions. 11. Remove slag and inspect for defects
3. Set joining pieces at right angle for 12. Deposit final run using weaving motion.
corner joint using fixture. 13. Clean welded joint and inspect for
4. Select welding rod 3.15 mm dia and defects.
set current 130 Amp.
Starting Date :
5. Tack weld at both the ends.
Finishing Date:
6. Clean tack weld and check for
alignment.
Instructor’s Observations:
7. Keep tacked pieces in flat position.

32. Material Name:
Size Instructor’s Signature:
Scale
Assignment 4
Join given pieces using tee fillet joint
You are provided with: 5. Set tee in flat position.
1. Safety devices.
6. Deposit root run with 3.15 mm
2. Electrical welding equipment
electrode and 130 Amp current.
3. Welding accessories.
4. Pieces of MS plate. 7. Ensure electrode angle 45o with
Procedure: surfaces and 80o with line of weld.
1. Take safety precautions. 8. Remove slag and clean.
2. Clean surfaces and square the edges. 9. Deposit covering run with 4 mm
3. Set pieces in inverted tee (⊥) shape set electrode and 170 Amp current.
right angle with square and hold pieces 10. Remove slag, clean and inspect for
with the help support. defects.
4. Tack welds the pieces at ends and
center.

33. Material Name:
Size
Instructor’s Signature:
Scale