2. Contents:
INTRODUCTION TO WELDING
HISTORY OF WELDING
PERSONAL PROTECTIVE EQUIPMENT (PPE)
SAFETY PRECAUTIONS
TYPES OF WELDING
WELDING JOINTS & POSITIONS
WELDING EQUIPMENT
ARC WELDING
MIG WELDING
WELDING ELECTRODES
DEFECTS IN WELDING
MERITS AND LIMITATIONS
APPLICATIONS
3. INTRODUCTION TO WELDING
Welding is a common process for joining the
ferrous and non ferrous metals permanently by
using the heat and pressure.
The metals are heated to their melting point , and
then a filler metal is added to the heated area to
produce a single piece of metal.
Nowadays we are using different types of welding
processes they are Pressure welding and Fusion
welding
4. History of welding
• Edmund Davy of England is credited with the
discovery of acetylene in 1836.
• The production of an arc between two carbon
electrodes using a battery is credited to Sir Humpy
Davy in 1800.
• In 1890, C.L. Coffin of Detroit was awarded the
first U.S. patent for an arc welding process using a
metal electrode.
• Oscar Kjellberg of Sweden invented a covered or
coated electrode during the period of 1907 to 1914.
5. PERSONAL PROTECTIVE EQUIPMENT (PPE)
Used properly, Personnel Protective Equipment (PPE) greatly
reduces the risk of injury and minimizes the effects of toxins.
6. SAFETY PRECAUTIONS
• As high current used in welding, it is essential to wear
gloves while switching on the mains to avoid electric
shocks.
• While welding, always wear PPE (helmet, apron ,safety
shoes, etc..,)
• Protect the power source from water.
• Always use good quality of products.
• Do not keep inflammable substances such as petrol and
kerosene near the welding set-up
8. Arc welding
Arc welding is one of the most popular type welding
methods.
Arc welding is a process that melts and joins metal by
applying heat with an electrode to form the weld pool on
work piece.
The electric energy is converted into heat energy,
producing a temperature of 3000°C to 4000°C.
Types of arc welding :
•
9. TYPES OF ARC WELDINGS:
• Flux –cored arc welding (FCAW)
• Gas metal arc welding (GMAW)
• Gas tungsten arc welding
• Plasma arc welding
• Shielded metal arc welding
• Submerged arc welding
10. Arc welding Equipment
Welding Generator (or) Transformer
Two cables- one for work and one for
electrode
Electrode holder
Electrode
Protective shield
Gloves
Wire brush
Chipping hammer
12. ELECTRODE CLASSIFICATION
For example, electrode is E6010
The prefix "E" designates an arc welding electrode. The first
two digits of a 4-digit number and the first three digits of 5-
digit number indicate minimum tensile strength. For
example, E6010 is a 60,000 psi tensile strength electrode
while E10018 designates a 100,000 psi tensile strength
electrode.
E - Electrode
60 - Tensile Strength
1 - Position
10 - Type of Coating and Current
13. Consumable And Non-consumable Electrodes
Consumable Electrode: Consumable electrodes are the ones that
would have significant changes in their structure when they are
used. This is to say that these electrode would be consumed in
their use.
Non Consumable Electrodes: Non consumable electrodes are
the ones that are not consumed during the process of welding.
15. Welding JOINTS
• Based on the position of work pieces, welded joints are classified
into following
(1) Butt joint (2) Lap joint (3) T- joint (4) Edge joint
(5) Corner joint
16. GROOVE WELDING AND FILLET WELDING
• GROOVE WELDING: A type of weld that consists of an opening
between two part surfaces, which provides space to contain
weld metal.
• Types of groove weldings:
17. • FILLET WELDING : Fillet welding refers to the process of joining
two pieces of metal together whether they be perpendicular or at
an angle.
• Example: Tee joint , lap joint.
20. MIG WELDING
MIG welding is a process in which an electric arc
formed between a consumable wire and the work
piece, which heats the work piece , causing them to
melt and join.
Rectifier is used as power source in MIG welding.
Carbon dioxide , methane and argon is used in MIG
welding.
21. WIRE FEED MECHANISM
There are three basic forms of wire feeders. They
are ‘push’ system, the ‘pull’ system and the ‘push–
pull’ system.
In the push system, the wire is pushed by the wire
feed drive rolls along to the welding torch.
The pull system utilizes a set of wire rolls in the
torch handle which pull the wire from the wire
reel.
The push–pull system is a combination of the above
two systems with a set of drive rolls at both the
wire reel feeder and in the torch.
23. Advantages of Welding
Welding is more economical and is much faster process as compared to
other processes (riveting, bolting, casting etc.)
Welding, if properly controlled results permanent joints having
strength equal or sometimes more than base metal.
Large number of metals and alloys both similar and dissimilar can be
joined by welding.
General welding equipment is not very costly.
Portable welding equipments can be easily made available
Welding permits considerable freedom in design.
Welding can also be mechanized
24. Disadvantages of Welding
It results in residual stresses and distortion of the work pieces.
Welded joint needs stress relieving and heat treatment.
Welding gives out harmful radiations (light), fumes and spatter.
Jigs, and fixtures may also be needed to hold and position the
parts to be welded.
Edges preparation of the welding jobs are required before
welding.
Skilled welder is required for production of good welding.
