Welding is a process that joins materials by heating them to a welding temperature through heating or pressure, with or without filler metal. There are several common welding processes including oxyacetylene welding, shielded metal arc welding (SMAW), gas tungsten arc welding (GTAW), gas metal arc welding (GMAW), and flux core arc welding (FCAW). When deciding which welding process to use, factors like equipment availability, joint geometry, material, and code requirements must be considered. SMAW is commonly used and involves creating an arc between a consumable electrode and the workpiece to produce coalescence.

1. Welding – (as defined by the American Welding Society (AWS)) – a joining
process that produces coalescence of materials by heating them to the welding
temperature, with or without the application of pressure or by the application of
pressure alone, and with or without the use of filler metal
1) Uses of welding –
A) Ships, buildings, bridges, recreational rides
B) Produce machines that are used to manufacture new products
C) Airplane and aerospace applications
D) Automobiles and farm equipment
E) Computer components
F) Very little in our modern world is not produced by using some type of
welding process
2) Processes
A) Oxyacetylene Welding
1. Oxyacetylene welding is the most commonly used fuel gas mixture.
It is widely used for welding(OFW), cutting (OFC), and brazing
(TB). The equipment required is relatively inexpensive and the cost
of operation is low.
B) Shielded Metal Arc Welding (SMAW), stick welding
1. The most common method of joining metal. High quality welds can
be made rapidly with excellent uniformity. A variety of metal types
and thicknesses can be joined with one machine.
C) Gas Tungsten Arc Welding (GTAW), Tig
1. Can be performed on almost any metal

2. 2. It produces clean, High quality welds that require little to no post
weld finishing
D) Gas Metal Arc Welding (GMAW)
1. Extremely fast and economical
2. Can be used to weld on thin gauge metal as well as thick plate.
3. GMAW has a high welding rate and reduced post weld cleanup.
E) Flux Core Arc Welding (FCAW)
1. utilizes same equipment as GMAW but may be used without an
external shield gas due to the use of a flux cored wire.
3) How do I decide on What welding process to use? Several factors must be
considered.
A) Availability of Equipment – types, capacities and condition of equipment
that can be used to make welds.
B) Repetitiveness of operation – How many welds will be required to do the
job, and are they all the same?
C) Quality Requirements – is the weld going to be used to repair a piece of
equipment or used on a piece of furniture
D) Location of work – will the weld be in a shop or in a remote job site?
E) Material to be joined – Are the parts made out of mild steel or an exotic
alloy?
F) Appearance of the finished product – is the weld needed to test an idea or
will it be a permanent structure?
G) Size of the parts to be joined – Are the parts small, large or of different
sizes? Can they be moved or must they be welded in place?
H) Time available for work – Is it a rush job or is there time for pre and post
weld cleanup?

3. I) Skill or experience of workers – do the welders have the ability to do the
job?
J) Cost of materials – will the weldment be worth the expense of special
equipment materials or finishing time?
K) Code or specification requirements – often the selection of the process is
dictated by the government agency, codes or standards.
4) SMAW equipment, setup & operation
A) Welding current
1. Welding current is an electric current (flow of electrons). Electrons flow
from negative (-) to positive (+) through a conductor.
2. Resistance to the flow of electrons produces heat. The greater the
resistance, the greater the heat.
a. Air has a high resistance to current flow. As the electrons jump
the air gap between the end of the electrode and the work, a great
deal of heat is produced. Electrons jumping the air gap create the
arc.
3. Current Measurement
a. Voltage (V) – Measurement of electric pressure. Voltage
controls the maximum gap the electrons can jump to form the arc. A
higher voltage can jump a larger gap.
b. Amperage, or Amps (A) – A measurement of the total number
of electrons flowing. Amperage controls the size of the arc.
c. Wattage (W) – a measurement of the electrical energy or power
in the arc. The amount of watts put into a weld controls the width
and depth of the weld bead.
d. Calculating currents:
Voltage x Amps = Watts
Watts/Voltage = Amps

4. Voltage = Watts/Amps
4. Welding Currents
a. Alternating Current (AC) – this setting evenly distributes the
heat between the electrode and work, even heat gives the weld bead a
balance between penetration and build up.
b. Direct Current Electrode Negative (DCEN)- electrode is
negative and work is positive. DCEN produces a high electrode
melting rate.
c. Direct Current Electrode Positive (DCEP) – produces the best
welding arc characteristics.
B.) Types of power Sources
1. Transformers
a. Transforms the high voltage, low amperage, Alternating current
supplied to welding shops to low voltage, high amperage
welding power.
2. Inverter
a. A much smaller welding power unit capable of producing the
same amount of power as a transformer machine 12 times its size.
One power source can also supply the power for several different
welding processes.

5. 3. Generators & Alternators
a. Alternator produces AC current
b. Generators produce AC or DC current
4. Rectifiers
a. Rectifiers convert AC power to DC power.
C.) Duty Cycle – Percentage of time a welder can be used continuously.
1. A 60% duty cycle means that out of every 10 minutes, the machine may
be used for 6 minutes at the maximum rated current
2. Exceeding the duty cycle can damage the insulation of the transformer,
damaging the power source.
D.) SMAW Electrodes
1. SMAW electrodes vary greatly and can be used for several different
applications.
2. Electrodes differ in strength, penetration, appearance, machineability,
etc.
3. Identifying electrodes:
a. E6011
i. E = electrode
ii. 60 = 60,000 tensile strength
iii. 3rd
number - 1 = welding positions, 1 = all
positions, 2 = flat and horizontal

6. iv. 4th
number – 1 = flux code, power supply, amount
of penetration, etc.
E.) Learning to Shield Metal Arc Weld
1. Get comfortable, wear protective gear: welding hood with correct lens
shade, coveralls, and Leather gloves.
2. If right handed hold the electrode holder in your right hand, in left hand
if left handed. Use other arm for support while welding.
3. When possible weld from left to right (right handers)
4. Striking the arc
a. Scratch electrode briskly over base metal and lift approximately
1/8th
inch
5. Hold the electrode at 15 – 30 degrees at 90 degrees with travel.
6. Arc length – the distance from the tip of the electrode to the base metal.
a. Arc length should be 1/16 inch to 1/8 inch maximum.
b. A short arc length will cause the electrode to stick, a long arc
length will prevent metal deposition and cause excessive spatter.
7. Welding speed
a. Watch the molten puddle, not the arc. The molten puddle should
be solid (not orange/red) approximately 3/8 inch behind the arc

7. b. A welding speed that is too rapid will create a thin bead with
little penetration and poor appearance.
c. A welding speed too slow will create a bead that is too wide, may
melt through the metal and also have a poor appearance.
8. Electrode manipulation (welding pattern)
a. Circular
b. C pattern
c. Zig –zag
d. Figure 8
e. J – pattern
f. Whip

8. F) Types of welds
1. Butt
a. Flat, Vertical, Horizontal, Overhead
2. Lap
a. Flat, Vertical, Horizontal, Overhead
3. T
a. Flat, Vertical, Horizontal, Overhead
4. Corner Joint
a. Flat, Vertical, Horizontal, Overhead
5. Edge Joint

9. a. Flat, Vertical, Horizontal, Overhead

10. a. Flat, Vertical, Horizontal, Overhead