Welding Shop workshop for nust mech courseWelding Shop workshop for nust mech course

1. Welding
ME-105 Workshop Practice
College of E&ME, NUST Pakistan

2. Welding
• Welding is a fabrication process that
joins materials by using heat to melt
the parts together and allowing them to
cool causing fusion.
• Welding is used for making permanent
joints.

3. Weld Joints

4. Types of Welding
Arc Welding
Shielded
Metal Arc
Welding
Gas Metal
Arc Welding
Gas Tungsten
Arc Welding
Gas Welding
Oxyacetylene
Welding
Resistance
Welding
Resistance
Spot Welding
Resistance
Seam
Welding
Energy Beam
Welding
Electron
Beam
Welding
Laser Beam
Welding
Solid State
Welding
Ultrasonic
Welding
Friction
Welding

5. Arc Welding
• The welding in which electric arc is
produce to give heat for the purpose of
joining two surfaces is called electric
arc welding.
• Electricity travels from
electrode to base metal
to ground.

6. Equipment
• A welding generator (D.C.) or Transformer
(A.C.)
• Two cables- one for work and one for electrode
• Electrode holder
• Electrode
• Protective shield
• Gloves
• Wire brush
• Goggles

7. Arc Welding

8. Shielded Metal Arc Welding (SMAW)
• It is one of the most common welding
process also known as stick welding.
• The electric current travels through
the air gap between the end of the
electrode wire and the base metal.
• As the electric current flows through
this air gap, an electric arc is formed.

9. Shielded Metal Arc Welding (SMAW)
• Electrode used is this process is
consumable, covered with flux. Electrode
melts and become a part of the weld.
• The flux forms a protective layer for the
weld.
• As the flux covering on the electrode wire
melts, a shielding gas is created.
• When the flux cools, it solidifies and forms
a protective slag over the weld bead.

10. SMAW - illustrated

11. Gas Metal Arc Welding (GMAW)
• GMAW employs a continuously feed electrode
and shielding gas. Shielding gas should be
inert.
• GMAW is also known as MIG (Metal Inert
Gas).
• Unlike SMAW, this process is relatively
faster since the electrode is fed continuously
to the welding area along with inert gas
• GMAW is also referred to as Metal Inert Gas
(MIG) Welding.

12. GMAW - illustrated

13. Advantages and Disadvantages of Arc Welding
•Advantages
 Most efficient way to
join metals
 Lowest-cost joining
method
 Affords lighter weight
through better
utilization of materials
 Joins all commercial
metals
 Provides design
flexibility
•Disadvantages
 Manually applied,
therefore high labor
cost.
 Need high energy
causing danger
 Not convenient
for disassembly.
 Defects are hard to
detect at joints.

14. Oxy-acetylene Welding
• Acetylene when combined with oxygen burns
at a temperature of 3000 °C to 3500 °C.
• As a fuel acetylene's primary disadvantage,
in comparison to other fuels, is high cost.

15. Equipment
• Gas Cylinders
Pressurized oxygen in one cylinder and
acetylene in the other cylinder.
• Regulators
Working pressure of oxygen 10psi
Working pressure of acetylene 5psi
• Pressure Gauges
• Hoses
• Welding torch
• Check valve
• Non return valve

16. Oxy Acetylene Welding- illustrated

17. Grove and Fillet Welding Positions
• Normally, the following numbers and letters are used.
• For groove welding positions-
• 1G – (flat welding position)
• 2G – (horizontal welding position)
• 3G – (vertical welding position)
• 4G – (welding position overhead or overhead)
• 5G – (uphill/downhill vertical welding position)
• 6G/6GR – (overhead vertical welding position)
• For fillet welding positions-
• 1F – (flat welding position)
• 2F – (horizontal welding position)
• 3F – (vertical welding position)
• 4F – (welding position overhead or overhead)

18. Grove and Fillet Welding Positions

19. Lab Task: Welding a Tee Joint
• Tee welding joints are
formed when two members
intersect at a 90° angle
which makes the edges come
together in the center of a
plate or component
• Tee Joints are considered a
type of fillet weld and can
also be made when a pipe or
tube is welded onto a base
plate