Welding is a process that joins metal materials by heating them to the point of melting. It is commonly used in manufacturing, construction, and repair. There are several welding processes that are classified as fusion welding, solid-state bonding, or brazing and soldering based on how heat and filler materials are applied. Arc welding is a common fusion welding method that uses an electric arc to melt metals and can include stick, MIG, TIG, and other techniques.

1. Welding Basics

2. Welding Definition
• A process used to permanently joining two
pieces of metal, usually by means of heat.

3. Welding Uses
Used in manufacturing to produce or repair…
• Barges
• Ships
• Storage tanks
• Pipelines
• Trains
• Automobiles
• Airplanes
• Home Appliances

4. Welding Uses (continued)
Used in construction to build…
Bridges
Buildings
Roller coasters

5. Welding Classification
There are many welding processes, which can be
classified into one of three groups
1. Fusion welding
2. Solid-state bonding
3. Brazing and soldering

6. Fusion Welding
• Uses heat to partially melt the metal surfaces
that are to be joined.
Common fusion welding processes
• Arc Welding
• Oxy-fuel welding
• Electric resistance welding
• Laser beam welding
• Electron beam welding
• Thermite welding

7. Solid-state bonding
• Uses pressure as well as heat to bond metal and
other materials.
Common solid-state bonding processes
• Diffusion welding
• Roll welding
• Friction welding
• Forge welding
• Ultrasonic welding
• Explosion welding

8. Brazing and Soldering
• Uses a melted filler metal to join usually close
fitting parts. The parts being joined do not
melt.
Brazing- uses fillers such as bronze, brass or a
silver alloy.
Soldering- uses fillers with lower melting points
such as lead-tin alloys.

9. Filler metal
• Most fusion welding uses a filler metal, which
is also melted and mixed with the material
being welded.
• The filler metal can either be a rod (stick) or a
consumable electrode.

10. Shielding
• Most fusion welding requires that the heated
metals be shielded from hydrogen, nitrogen
and oxygen in the atmosphere.
• If metals absorb these gases, the weld could
be weak or brittle.

11. Shields
Shielding is done by flux, a vacuum or
an inert gas
• Flux- a chemical substance used to clean metal of
oxides and other impurities.
• Vacuum- a space without matter
• Inert gas- A gas that normally does not combine
chemically with the base metal or filler metal.

12. Arc Welding
• Uses a welding power supply to create an
electric arc between the electrode and the
base material to melt the metals at the
welding point.

13. Electric Arc- The flow of electric current
present between two electrodes, formed
when electricity jumps from one
electrode to another.
Electrode- A conductor that passes an
electrical current from one medium to
another.

14. Common types of Arc Welding
• Shielded metal arc welding (SMAW) also called
manual metal arc welding (MMAW) or stick
welding
• Gas metal arc welding (GMAW) also called Metal
inert gas (MIG) welding
• Flux-cored arc welding (FCAW)
• Submerged arc welding (SAW)
• Gas tungsten arc welding (GTAW) also called
tungsten inert gas (TIG) welding

15. Flux-cored arc welding (FCAW)
• FCAW wire is actually a fine metal tube filled
with powdered flux materials. An externally
supplied shielding gas is sometimes used, but
often the flux itself is relied upon to generate
the necessary protection from the
atmosphere.

16. Submerged arc welding (SAW)
• A high-productivity welding process in which
the arc is struck beneath a covering layer of
granular flux. This increases arc quality, since
contaminants in the atmosphere are blocked
by the flux.

17. Gas tungsten arc welding (GTAW) also
called tungsten inert gas (TIG)
welding
• A manual welding process that uses a non-
consumable electrode made of tungsten, an
inert or semi-inert gas mixture, and a separate
filler material.
http://www.youtube.com/watch?v=FD7fcdFESo
s&feature=c4-overview-
vl&list=PLDFAD0F77CEEE7654

18. Shielded metal arc welding (SMAW)
or stick welding
• An electric current is used to strike an arc
between the base material and a consumable
electrode rod or stick.
• http://www.youtube.com/watch?v=JEF0_yTTL
7w

19. Gas metal arc welding (GMAW) Metal
inert gas (MIG) welding
• Uses a continuously fed consumable wire acting
as both electrode and filler metal, along with an
inert or semi-inert shielding gas flowed around
the wire to protect the weld site from
contamination.
http://www.youtube.com/watch?v=UeiPOQQirk4&l
ist=PLDFAD0F77CEEE7654&feature=c4-overview-vl

20. MIG Diagram

21. MIG Diagram

22. Common Welding Joints