Shielded Metal Arc Welding (SMAW) - Part A

Shielded Metal Arc Welding (SMAW) - Part A
320102cA
Agricultural Equipment Technician
Shielded Metal Arc Welding
(SMAW) - Part A
Electric Welding and Oxyfuel Cutting
First Period
Table of Contents
Objective One ............................................................................................................................................... 2 Definitions................................................................................................................................................. 2 Basic Joints ............................................................................................................................................... 9 Welding Positions ................................................................................................................................... 10 Groove Weld Edge Preparations ............................................................................................................. 11 Weld Components ................................................................................................................................... 12 Structural Shapes .................................................................................................................................... 13 Objective Two............................................................................................................................................. 14 Machine Types ........................................................................................................................................ 14 Welding Currents .................................................................................................................................... 18 Objective Three ........................................................................................................................................... 21 Machine Installation and Maintenance ................................................................................................... 21 Objective Four ............................................................................................................................................ 26 Equipment Set-Up ................................................................................................................................... 26 Objective Five ............................................................................................................................................. 27 Types of Welding Electrodes .................................................................................................................. 27 The SMAW Process ................................................................................................................................ 28 The Core Wire......................................................................................................................................... 28 The Coating ............................................................................................................................................. 29 Electrode Classification System.............................................................................................................. 30 Objective Six............................................................................................................................................... 32 Dynamic and Static Loading Considerations .......................................................................................... 32 Types of Coatings ................................................................................................................................... 34 Specific Information on Mild Steel Electrodes ....................................................................................... 37 Electrode Selection Simplified................................................................................................................ 39 Metal Identification ................................................................................................................................. 41 Self-Test ...................................................................................................................................................... 44 Self-Test Answers ....................................................................................................................................... 49 Shielded Metal Arc Welding (SMAW) Part A
NOTES
Rationale
Why is it important for you to learn this skill?
The shielded metal arc welding (SMAW) (manual arc welding) process is commonly
used in many phases of agricultural equipment repair. You must know the safety
requirements, machine set-up and adjustments, electrode selection and puddle control
techniques in order to make these necessary repairs. This module provides the
information required to perform these welding operations.
Outcome
When you have completed this module you will be able to:
Perform welding operations using arc welding equipment.
Prerequisites
At this point, you should have completed the following modules:
 320102a Welding Safety
 320102b Oxyfuel Equipment
Objectives
1.
2.
3.
4.
5.
6.
Define basic electricity terms related to arc welding.
Describe selected machine types, welding currents and polarities.
Describe care and maintenance procedures of arc welding equipment.
Demonstrate equipment set-up and adjustments.
Describe the electrode designation system.
Select electrodes for specific applications.
Introduction
This module will cover safe operation and adjustment of arc welding machines. The
module is designed to introduce you to puddle control techniques and to develop your
hand skills at performing beads and fillet welds on mild steel using the SMAW process.
This module presents information necessary to select the correct electrode for the
application at hand.
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Objective One
When you have completed this objective you will be able to:
Define basic electricity terms related to arc welding.
Definitions
In order for you to gain an understanding of basic electricity and welding power sources,
you must first understand some basic terms associated with this subject matter. The
following terms are used throughout the trade and you should become familiar with these
terms in order to communicate with others in the trade.
2
Term
Definition
alternating
current (AC)
Alternating current (AC) is current that flows in one direction
during any half cycle, then reverses and flows in the opposite
direction during the next half cycle. The rate at which this
alternating occurs is measured as cycles per second, with 60cycle AC being the most common in North America.
amperage
Amperage is also known as heat setting. Amperage is the current
flow through the welding cables while welding. A welding
machine is manufactured to have a maximum amperage output
(for example, 200 amps, 250 amps or 300 amps). The operator
can select the welding amperage, within the limits of the
machine, to suit the requirements of the job at hand. This is the
electrical property that causes the electrode, the parent metal, or
both, to be melted. Amperage in arc welding is responsible for
the following.
 Metal deposition rate (also known as burn-off rate).
If the amperage is increased, there is a proportionate
increase in the metal deposition rate of the electrode. A
decrease in amperage results in a decrease of the metal
deposition rate.
 Penetration: Increasing the amperage causes the arc to
penetrate or burn deeper into the parent metal and
lowering the amperage causes a decrease in penetration.
arc
In welding, an arc is created when there is enough amperage and
voltage available at the electrode tip to overcome the natural
resistance to the flow of electricity. This resistance is usually
caused by the air gap between the electrode and the work. The
heat of the arc melts the base plate and the electrode.
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Term
Definition
arc blow
Arc blow is a condition encountered when welding with direct
current that causes the arc to flare uncontrollably from side to
side. Puddle control is very difficult and the subsequent weld
quality is very poor. Arc blow is caused by magnetic fields being
set up around the work. This is due to current travelling in the
same direction for a prolonged period of time. Arc blow is not a
problem when welding with AC because the reversals in the
direction of current flow prevent the accumulation of magnetic
fields being set up around the work.
If it is not possible for you to change to an AC power source, arc
blow can be minimized or eliminated by:
 changing the position of the ground clamp,
 using a different electrode angle or electrode inclination,
 welding toward a heavy tack or existing weld,
 welding in the opposite direction,
 positioning the object being welded on so it is in contact
with the earth,
 using a lower current setting and/or
 wrapping the ground cable around the pipe a few times,
as in pipe line welding. If that is not successful, wrap it
in the opposite direction.
arc voltage
Arc voltage is the voltage output of the machine while welding
is being done. It is the force that maintains the current flow
across the arc between the electrode and the workpiece. Higher
arc volts improve arc stability and also increase the amount of
heat in the arc, thus causing the puddle to be more fluid. There is
not an adjustment to the arc volts on most manual arc welding
machines. The operator can influence the arc voltage by varying
the length of the arc.
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Term
buzz box
Definition
The term buzz box is often used to describe an AC transformer
type welding machine because of the typical buzzing sound
made when welding with them. Figure 1 illustrates an
inexpensive AC transformer type welding machine. Settings
tend to be rather coarse; typically ten to twenty amps per step.
Each step or tap is connected to a fixed position on the
secondary coil in the machine.
Figure 1 - AC transformer welder with step controls (taps).
4
circuit
Any system of conductors that is designed to complete the path
of an electric current is called a circuit. Current flows in the
conductor when voltage is applied to it.
core
The core is the magnetic link between the primary and the
secondary coils of a welding transformer. The core can be
moved into, or out of, the coil as a method of current control.
This type of current control is called movable shunt. A movable
shunt means that the core can be moved into different positions
thus, influencing the magnetic link between the primary and
secondary coils. The shunt is usually moved mechanically by an
external hand crank that controls its movement on a slide
assembly. This allows for any setting between minimum and
maximum of the machine's output potential.
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Term
Definition
coil
A coil is usually made of insulated copper wire and is designed
to have a certain number of turns of wire. The coil can be moved
over or away from the core as a method of adjusting the welding
current. Figure 2 illustrates an AC transformer type welding
machine with a fixed primary coil, a fixed secondary coil and a
movable shunt.
Figure 2 - Coils and movable shunt in an AC welding machine.
A conductor is a material or substance that is capable of
conductor
transmitting electricity. Most metals are good conductors
because they offer little resistance to current flow.
constant current
(CC)
Constant current (CC) is a term denoting a welding machine
suitable for SMAW and GTAW. These machines typically
produce a relatively high open circuit voltage to assist in
establishing a welding arc. These machines produce a steep or
drooping volt-amp curve.
constant voltage
(CV)
Constant voltage is also known as constant potential A term
denoting a welding machine suitable for GMAW, FCAW and
SAW. These machines produce a relatively stable voltage
regardless of the amperage output of the machine. These
machines produce an almost flat volt-amp curve.
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Term
Definition
cycle
A cycle is one complete rotation of the sine wave pattern as
illustrated in Figure 3. The sine wave begins at zero, climbs to
its maximum positive value, then drops back through zero and
becomes negative. It reaches its maximum negative value, then
proceeds to zero again. This movement is one full cycle of AC
current. With 60-cycle AC, the current changes direction 120
times per second.
Figure 3 - One cycle of alternating current (sine wave).
direct current
(DC)
Direct current (DC) is electric current that flows in one direction
only and has either a positive or negative value. There is no
change of current flow direction as there is with AC. The
electron theory states that current flows from negative to
positive.
duty cycle
All welding machines are rated by the National Electrical
Manufacturers Association (NEMA). The rating is based on
maximum output over a ten-minute time period. This rating is
expressed as a percentage of the time that the machine can run at
maximum rated output current before it must be allowed to cool
down. For example, a machine rated at 300 amps with a 60%
duty cycle can operate at maximum rated amperage for six
minutes out of ten without causing damage by overheating.
Also, if the machine was required to run continuously, it could
safely run at 60% of 300 amps, or 180 amps maximum. (This is
a rule of thumb calculation for estimating other than rated
output). Exceeding duty cycle ratings can damage or ruin a
welding power source.
flux core arc
welding (FCAW)
Flux core arc welding uses GMAW equipment and process, but
uses flux core wire rather than solid core wire. Shielding gas can
be externally applied and/or obtained within the hollow
electrode core. FCAW is used extensively in the fabrication
industry for welding of carbon and alloy steels, stainless steels
and hard surfacing applications.
A generator is a machine used to create electricity of sufficient
volume for welding. A shaft, with an electrical conductor, is
rotated perpendicular to a magnetic field. Generators produce
generator
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Term
Definition
either AC or DC depending on their internal configuration.
gas metal arc
welding (GMAW)
Gas metal arc welding, (Figure 4), commonly referred to as
MIG (metal inert gas) welding, is an arc welding process that
fuses metal by heating it with an electric arc established between
a continuously fed filler metal (consumable solid wire) electrode
and the workpiece. Appropriate settings made by the operator
maintain a constant burn-off rate of the wire electrode.
Depending upon the power source and wire drive system used,
the arc length is maintained automatically. Atmospheric
contamination is prevented by using an externally applied
shielding gas
gas tungsten arc
welding (GTAW)
NOTES
Figure 4 - Gas metal arc welding process.
Gas tungsten arc welding, (commonly referred to as TIG tungsten inert gas) is a process in which fusion welding is
accomplished by the heat of an electric arc drawn between a
non-consumable tungsten electrode and the workpiece. The
electrode, arc, weld puddle and the adjacent heated area of the
workpiece are protected from atmospheric contamination by an
externally applied gaseous shield. Filler rod is added manually.
GTAW is easily adapted for welding a wide variety of ferrous
and non-ferrous metals with high quality control.
inverter
An inverter is a device that changes DC to AC. In welding
machines, inverters are also used to increase the frequency of
AC.
metal inert gas
(MIG)
open circuit
voltage (OCV)
See GMAW.
When a welding machine is turned on, but no current is flowing
in the circuit, open circuit voltage is the potential force available
to initiate the current flow when the arc is struck. Open circuit
voltage is built into the machine and is not adjustable by the
operator. 80 OCV is the maximum available for safety reasons.
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8
Term
Definition
A machine with high OCV will have superior operator appeal.
The arc is easier to strike and the arc voltage will be higher,
creating better arc stability.
rectifier
A rectifier is a device that changes AC to DC by allowing
current to flow in one direction only.
resistance
Resistance is the property of an electrical conductor to oppose
the flow of current, causing electrical energy to be turned into
heat. Resistance is measured in ohms and is calculated by
dividing voltage by amperage (Ohms = V/A). The air gap (arc
length) offers resistance to current flow. It is this resistance to
the flow of current across the arc that creates the heat needed for
welding.
reverse polarity
(DCRP)
Direct current reverse polarity, direct current electrode positive.
In a SMAW DC welding circuit, reverse polarity occurs when
the electrode cable is connected to the positive terminal of the
welding machine. For more details, see the sections on Machine
Types and Welding Currents in Objective Two.
shielded metal arc
welding (SMAW)
Shielded metal arc welding is a manual arc welding process that
fuses metal using the heat from an electric arc established
between a consumable stick electrode and the workpiece.
Appropriate settings made by the operator maintain a constant
burn-off rate of the electrode. The operator controls the molten
puddle and ultimately the finished weld by manually
manipulating the arc length, the electrode angle relative to the
workpiece and the rate of travel. The electrodes are supplied
with a coating that breaks down during the welding process to
produce a protective gaseous shield around the molten puddle
and also a slag cover to protect the cooling weld.
straight polarity
(DCSP)
Direct current straight polarity, direct current electrode
negative. In a SMAW DC welding circuit, straight polarity
occurs when the electrode cable is connected to the negative
terminal of the welding machine. For more details, see the
sections on Machine Types and Welding Currents in Objective
Two.
voltage
Voltage is the electrical pressure or force that causes current to
flow in a conductor or to cross the arc gap. Voltage in arc
welding is responsible for the following.
 Starting the arc: With constant current welding
machines, open circuit voltage needs to be quite high
(80 volts) in order to initiate an arc.
 Maintaining the arc: Arc voltage must be present to
maintain the arc (typically 17 to 40 volts).
 Puddle fluidity and puddle flow: Arc voltage directly
affects both the width of the weld bead and the fluidity
or wetness of the puddle. An increase in arc voltage
causes an increase in puddle width and fluidity, while a
decrease in arc voltage, causes the puddle to be
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Term
Definition
narrower and less fluid.
welding machine
(welding power
source)
A welding machine is an apparatus that is specifically designed
to deliver an electric current of proper voltage to amperage ratio
and of sufficient capacity for welding.
Basic Joints
Basic joints are shown in Figure 5.
Figure 5 - Basic joints.
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Welding Positions
Welding positions are shown in Figure 6.
Figure 6 - Welding positions.
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Groove Weld Edge Preparations
Groove weld edge preparations are shown in Figure 7.
Figure 7 - Groove weld edge preparations.
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Weld Components
Weld components include the following.
Fillet Weld
A fillet weld is shown in Figure 8.
Figure 8 - Fillet weld.
Groove Weld
A groove weld is shown in Figure 9.
Figure 9 - Groove weld.
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Structural Shapes
Various structural shapes are shown in Figure 10.
Figure 10 - Structural shapes.
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Objective Two
When you have completed this objective you will be able to:
Describe selected machine types, welding currents and polarities.
Machine Types
There are three main types of welding machines. They are:
 alternating current (AC) transformers,
 AC/DC transformer-rectifiers and
 generators and alternators.
Alternating Current Transformers
Alternating current transformer welding power sources convert the typical high voltage,
low amperage alternating current available at an electrical outlet in your shop, to low
voltage, high amperage AC current that is suitable for welding. Figure 11 is an AC
transformer type welding power source that has a welding current range of 40 to 225
amperes. It produces a smooth AC arc for welding a wide variety of materials including
low carbon, low alloy and stainless steels.
Figure 11 - AC transformer welding power source. (Courtesy Lincoln Electric)
Table 1 outlines advantages and disadvantages of the AC transformer.
AC Transformers
Advantages
Low initial cost
Low maintenance
Lower operating costs
Generally quiet operation
No accumulative arc blow
Disadvantages
Not portable
No choice of polarity
Limited electrode selection
More difficult to strike and maintain an arc
Restricted welding processes
Table 1 - Advantages and disadvantages of an AC transformer.
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AC-DC Transformer-Rectifier Power Sources
AC-DC transformer-rectifier welding machines are AC transformers to which a rectifier
is added. The rectifier unit is made up of diodes that are capable of allowing current to
flow in one direction only, thus changing AC to DC. Table 2 outlines advantages and
disadvantages of the AC-DC transformer-rectifier.
AC-DC Transformer-Rectifiers
Advantages
May have AC and DC output capability
Full selection of electrodes
Choice of polarity
Few moving parts
Disadvantages
Generally more costly than transformers
Arc blow can be a factor with DC
Not portable
Requires a relatively clean, cool
environment
Quiet
Table 2 - Advantages and disadvantages of an AC-DC transformer-rectifier.
The welder in Figure 12 is using an AC-DC transformer-rectifier welding power source
to lay a root bead using direct current reverse polarity with an E41010 (E6010) electrode.
Figure 12 - Transformer rectifier power source. (Courtesy Miller Electric Mfg. Co.)
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Generators and Alternators
Generator and alternator power sources may be driven by gasoline, diesel or propane
fuelled engines or by an electric motor. These machines are available to provide output of
AC only, both AC and DC or DC only. Many machines can provide welding current as
well as auxiliary AC to operate power tools. These power sources provide a smooth,
constant, stable arc and thus have good operator appeal. The main advantage of the
engine driven machines is portability. For example, commercial garage door installers or
commercial sign installers often equip their rigs with small engine driven AC alternators
(Figure 13).
Figure 13 - Engine driven AC alternator. (Courtesy Miller Electric Mfg. Co.)
The welding machine in Figure 14 is a DC generator driven by a diesel engine. Notice the
dual controls for setting voltage and amperage. This unit also has the capability of
producing 3000 watts of AC auxiliary power to run power tools and other equipment.
Figure 14 - DC generator power source driven by diesel engine.
(Courtesy of Lincoln Electric)
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Figure 15 is an example of an engine driven alternator design that also has the capability
of producing 3000 watts of AC auxiliary power. The control panel features a stepped
coarse amperage control and a fine amperage adjustment rheostat arrangement.
NOTES
Figure 15 - Engine driven AC alternator design welder.
(Courtesy Miller Electric Mfg. Co.)
Table 3 outlines advantages and disadvantages of the DC generator and alternator.
DC Generators and Alternators
Advantages
Choice of polarity
Smoother arc than with AC
May be portable
Full choice of electrodes
Often have auxiliary power output to
run lights and power tools
Disadvantages
High initial cost
Higher maintenance costs than transformer
sets
Higher operating costs than transformer sets
Generally noisier than transformer sets
Arc blow is a factor with DC
Table 3 - Advantages and disadvantages of a DC generator and alternator.
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Welding Currents
The two types of current used in welding are:
 direct current (DC) and
 alternating current (AC).
Direct Current
Direct current flows in one direction only and has either a positive or negative value.
There is no change of direction as there is with AC. The electron theory states current
flows from negative to positive. The operator can select the direction of current flow
across the arc by connecting the electrode to the negative pole (straight polarity) or the
electrode to the positive pole (reverse polarity). Each polarity produces unique welding
characteristics. All SMAW electrodes will function on DC. Some rods will work best on
straight polarity and some are designed to be used with reverse polarity. Given a choice,
most welders will prefer to use DC rather than AC because of superior versatility and arc
stability.
Direct Current Straight Polarity
Direct current straight polarity (DCSP), direct current electrode negative. In a SMAW
DC welding circuit, straight polarity occurs when the electrode cable is connected to the
negative terminal of the welding machine. You may be able to remember the terminology
if you think of the negative sign (–) as being a straight line.
Using straight polarity with SMAW results in the following electrode and arc
characteristics.
 The electrode melts somewhat faster, which results in faster metal deposit.
Approximately two thirds of the arc energy is associated with the electrode
(negative terminal).
 Penetration is shallow.
 Metal flow is somewhat wider.
Figure 16 is an illustration of a DC welding machine that is connected to straight polarity.
Figure 16 - Straight polarity (electrode negative).
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Direct Current Reverse Polarity
Direct current reverse polarity (DCRP), direct current electrode positive. In a SMAW
DC welding circuit, reverse polarity occurs when the electrode cable is connected to the
positive terminal of the welding machine. Using reverse polarity with SMAW results in
the following electrode and arc characteristics.
 The electrode melts somewhat slower and allows slower metal deposit.
Approximately two thirds of the arc energy is associated with the base metal
(negative terminal).
 Penetration is deeper, especially with a short arc length.
 Metal flow is generally narrow, unless a longer arc length is used.
Reverse polarity is the preferred choice when welding in deep grooves, when welding in
vertical and overhead positions and for multi-pass welds. The E6010, E6011 and E7018
electrodes that you will use most often in relation to repair and modification of
agricultural machinery and equipment are designed to be used on reverse polarity rather
than straight polarity. When in doubt, choose reverse polarity.
Figure 17 is an illustration of a DC welding machine that is connected to reverse polarity.
Figure 17 - Reverse polarity (electrode positive).
NOTE
To test for polarity, you can use an E6010 electrode. With normal heat
settings for the electrode and using reverse polarity, the arc is fairly
quiet (sounds like bacon frying), deeply penetrating and with minimal
spatter. With the same current setting and using straight polarity, the
arc emits a loud hissing sound with shallow penetration and there is
much more spatter and smoke fumes emitting from the arc.
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NOTES
Alternating Current (AC)
Alternating current reverses or changes direction of flow according to the number of
cycles per second that the current is being produced. In North America, 60 cycle current
is standard. With AC, the welding arc is somewhat less stable due to the changing of
current flow across the arc. Some electrodes will loose the arc when used on AC. With
alternating current, there can be no fixed polarity. The arc characteristics and weld results
using AC is an average of the weld characteristics between direct current electrode
positive and direct current electrode negative.
Figure 18 shows a single cycle of alternating current.
Figure 18 - One cycle of alternating current (sine wave).
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Objective Three
When you have completed this objective you will be able to:
Describe care and maintenance procedures of arc welding equipment.
Machine Installation and Maintenance
Here are some guidelines you should follow when installing electric welding machines.
 Install the machine in an area as dust free as possible that is sheltered from wet or
rainy conditions, is handy to the work area, but is protected from damage due to
work activities. Make sure there is plenty of air movement for the fan motor unit
to help keep the machine cool.
 Installation must meet applicable electrical codes and be performed only by
qualified personnel.
DANGER
Input current for most industrial quality welding machines is
potentially deadly. Do not attempt to install the equipment unless you
are qualified to do so. Do not attempt to repair cracked or torn input
cables unless you are qualified to do so.



Input power must be compatible with the machine manufacturer's
recommendations.
Machines must be properly grounded to prevent electrical shock.
All electrical connections must be clean and tight.
The following are some guidelines to follow with respect to machine maintenance.
 Blow out internal components periodically with high-volume, low-pressure air,
following the manufacturer's recommendations.
 Lubricate any bearings, bushings or mechanical controls by following the
manufacturer's recommendations.
 Ensure that all electrical connections are clean and tight and that insulation is not
cracked or torn.
 On engine driven machines, follow the engine manufacturer's recommendations
for service requirements.
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Welding Cables
Welding cables are flexible electrical lines consisting of many strands of fine copper wire
encased in a rubber covering. Their primary purpose is to transmit welding current from
the welding machine to the workpiece and back to the machine. Protect the cables from
damage when not in use by coiling them up neatly and out of the sunshine and weather.
When welding, position the cables such that they will not be subjected to damage from
hot sparks, hot slag, hot metal and falling metal objects.
Cables are available in eight standard sizes in order to accommodate the wide range of
welding currents used with different processes or to match job conditions without
significant voltage loss. In Table 4, the sizes of welding cables range from the smallest
(#4) to the largest (#4/0).
Welding Cable Size Numbers
4
Smallest 
3
2
1
1/0
4Largest
2/0
3/0
4/0
Table 4 - Welding cable sizes numbering system.
If you have to join two cables of different sizes together, the largest size cable should be
connected to the power source and the smallest size cable should be connected to the
electrode holder.
Table 5 gives the recommended size of welding cable using the variables of amperage
and distance from the power source. The distance is dependent on the total distance from
the welding machine to the work and back to the machine. Some voltage drop may occur
depending on the total length of the cables used.
Recommended Welding Cables Sizes
Amps
100
150
200
250
300
350
400
450
500
550
600
18
4
2
2
2
1
1/0
1/0
2/0
2/0
3/0
3/0
30
4
2
2
2
1
1/0
1/0
2/0
2/0
3/0
3/0
Distance in Metres from the Welding Machine
38
45
53
60
68
76
84
90
4
4
2
2
2
2
1
1
2
2
1
1
1/0 1/0 2/0 2/0
2
1
1/0 1/0 2/0 2/0 3/0 3/0
1
1/0 2/0 2/0 3/0 4/0
1/0 2/0 3/0 3/0 4/0
2/0 3/0 4/0
2/0 3/0 4/0
3/0 4/0
3/0 4/0
4/0
4/0
Table 5 - Recommended sizes of welding cables.
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1/0
3/0
4/0
120
1/0
3/0
4/0
NOTES
Cable Connectors and Cable Lugs
Cable connectors are used to connect lengths of welding cable together. Cable connectors
and lugs are sized by their amperage ratings. One convenient method of joining welding
cables is to use a mechanical connector. The bare wire is inserted into the connector and
the connector has a lug that is hammered to squeeze it onto the cable. These connectors
must be thoroughly wrapped with electrical tape to prevent accidental arcing.
A quick-connect type connector is also available with male and female ends that twist
and lock together Figure 19A). Connectors are made of electrically conductive material
such as brass or copper and must be clean and fit snugly together to provide good
electrical transfer so overheating does not result.
Lugs are used for attaching cables to machines, work clamps or work tables (Figure 19B).
Lugs are usually made of copper and are not insulated so good electrical contact can be
made. Connections must be clean and tight.
It is important to use the correct size of lug or connector for the size of cable needed
because an undersized lug or connector will overheat under high current load conditions.
Figure 19 - Cable connectors and cable lugs.
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Electrode Holders
Electrode holders (also known as stingers) come in two basic types, which are listed
below.
 The alligator jaw type (Figure 20A) clamps the bare end of the electrode in a
spring-loaded jaw.
 The twist head type (Figure 20B) has the bare end of the electrode inserted in the
head and then tightened into place by mechanical pressure as the head is twisted.
Figure 20 - Electrode holders.
All electrode holders are rated by their amperage carrying capacity (for example,
200 amp or 300 amp). The size of electrode holder you choose must match the amperage
you are using and the size of welding cable you have. The twist head type electrode
holder has a removable head that can be replaced without having to disconnect the
welding cable and replace the entire holder. The handle of any type of electrode holder is
well insulated to protect you from electric shock and heat. The insulated holder also
prevents accidental arc strikes when the welding circuit is energized.
24
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Ground Clamps
Ground clamps are used to complete the welding circuit. They may be a spring-loaded
clamping device, a magnetic clamp, a C-clamp device or a lug welded to the work and
then securely attached to the end of the work lead cable. Regardless of the type of ground
clamp used, it is very important that you have a clean, tight connection.
The spring-loaded clamping devices in Figure 21 make the location of the work lead easy
to change, if required. Make sure the spring is forcing the clamp to make a tight
connection on the work. These are the most common types for general purpose SMAW.
Figure 21 - Spring-loaded work lead clamps.
Be aware that a poor ground connection can cause accidental arcing. This accidental
arcing may at best cause a surface cosmetic problem or may result in extremely hard and
brittle spots to form on the workpiece affecting the metallurgical and structural integrity
of the metal. Never connect the ground clamp onto a machined surface to avoid arcing
damage to that surface. Also, never place the ground clamp where there is a danger of
current passing through a bearing or bushing because arcing may occur within and
damage the bearing parts and surfaces. This is particularly important when preparing to
weld on machinery or machine components.
Since a poor ground connection results in increased resistance to current flow, you may
experience an unstable arc or overheating in your welding cables, especially at the cable
connections.
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Objective Four
When you have completed this objective you will be able to:
Demonstrate equipment set-up and adjustments.
Equipment Set-Up
When setting up for welding activities, the following items are worthy of consideration
with respect to convenience and safety as well as performance.
 Position the welding power source nearby so it is convenient to make necessary
adjustments, yet it is out of harm's way relative to flying grinding sparks, welding
spatter and moving machinery.
 Lay out the cables neatly to minimize a tripping hazard and cable damage from
welding fallout.
 Switch the machine on.
 Select welding current and polarity relative to the electrode to be used.
Set the Amperage
Follow this procedure to set the amperage.
 Make a rough estimate for a setting to start at. Base your estimate on past
experiences using a similar electrode. Make proportional adjustments relative to
wire size and coating thickness. Make reference to the electrode manufacturer's
recommendations, if available.
 Set up a sample weld joint of similar thickness and position as the actual job at
hand. Do some practice welds. By trial and error, observing the arc, puddle and
weld characteristics and make fine tune adjustments to the amperage setting on
the machine until you achieve the desired results.
NOTE
Avoid making amperage adjustments and polarity switching while the
machine is actually welding. This is to avoid arcing within the
machine components. You can leave the input power switch on, but
simply stop welding, make adjustments, then continue welding.
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Objective Five
When you have completed this objective you will be able to:
Describe the electrode designation system.
Types of Welding Electrodes
The two types of welding electrodes are:
 non-consumable and
 consumable.
Non-Consumable Electrodes
Non-consumable electrodes are not intended to be consumed into the weld puddle. Nonconsumable electrodes are energized and usually form one of the electrical poles involved
in the creation of an electric arc between the electrode and the workpiece. For example,
with gas tungsten arc welding (GTAW), an electric arc is drawn between a nonconsumable tungsten electrode and the work. If filler metals are used, they are fed from
an external source. The tungsten electrode's function is to enable the creation of an
electric arc between itself and the workpiece.
Consumable Electrodes
When you are using shielded metal arc welding (SMAW), you are using consumable
electrodes, which means the electrode is melted into the weld puddle (consumed). A
consumable electrode therefore, is called a filler rod because the metal from the electrode
is melted into the weld. Arc welding processes usually require filler metals in order to fill
the weld joint and to produce desirable properties of the finished weld. The American
Welding Society (AWS) and the Canadian Standards Association (CSA) have developed
specifications for carbon steel filler rods when using SMAW.
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The SMAW Process
SMAW is also known as stick welding and the electrode is sometimes called a rod. The
electrode has a metal core wire and is covered with material that is called the flux
coating. The ingredients in the coating are responsible for different operating
characteristics and different weld deposit properties of the electrode. The development of
flux-coated electrodes has resulted in the capability for making welds with properties that
equal or exceed those of the parent metal.
The electrode is being consumed into the parent metal to form the weld bead and slag
covering. Figure 22 illustrates a coated electrode. The size of the electrode is determined
by the diameter of the core wire only. The thickness and composition of the flux coating
is different, depending on which type of electrode you are using.
Figure 22 - Coated SMAW electrode.
The Core Wire
For the common E60 and E70 series of electrodes, the core wire is generally from the
same wire stock. (It is an SAE 1010 carbon steel with a carbon range of 0.05 to 0.15%).
Wire Size
Electrodes are available in the following wire sizes: 1/16" (1.6 mm), 3/32" (2.5 mm), 1/8"
(3.2 mm), 5/32" (4.0 mm) and 3/16" (5.0 mm). In North America, electrodes are
manufactured in imperial fractional diameters. The welder selects the wire size of a
specific electrode type to suit the job at hand. Electrodes 1/8" in diameter are required
most often for repair and fabrication welding in all positions. Smaller electrodes are
selected to weld on light gauge metal. Larger electrodes are selected to make efficient
large welds in the flat and horizontal positions on thick plate. Electrodes larger than 1/8"
produce a large molten puddle which is difficult to control in the vertical and overhead
positions.
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The Coating
The coating (flux) on arc welding electrodes is a mixture of chemicals and binders baked
onto the wire core. The burning or breaking down of the coating in the heat of the arc
influences the weld quality and arc characteristics associated with each type of electrode.
Functions of the Coating
Functions of the coating are listed below.
 It stabilizes the arc. It provides ease of striking and helps maintain the arc.
 A gaseous shield is formed, thus excluding harmful oxygen and nitrogen from
the molten puddle and the molten end of the electrode.
 It provides a slag cover over the deposited weld metal to exclude oxygen and
nitrogen from the weld while it is cooling. The slag collects the impurities as they
float to the surface of the puddle. The slag controls the shape and smoothness of
the bead and controls the cooling rate, which improves the physical properties of
the weld metal.
 It deoxidizes or dissolves oxides that form during the welding process and
provides a cleaning action.
 It directs the arc from the end of the electrode. The wire core melts away faster
than does the coating, thus creating a nozzle effect.
 It regulates the depth of penetration. Certain coating types cause a more forceful
arc than do others.
 It serves as an insulator so an arc cannot be struck along the side of the electrode.
 Alloy elements are easily introduced into the weld deposit by way of the coating,
rather than by using an alloy core wire. The properties of the weld can be
influenced by the addition of alloys.
Figure 23 illustrates the melting of the electrode in the arc column and the resulting weld
metal deposit covered by the slag.
Figure 23 - Electrode coating and formation of slag.
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Electrode Classification System
SMAW electrodes designed for repair and fabrication of carbon steel are manufactured in
accordance with a number standards, such as CSA W48.1 and AWS A5.1, as designated
by the Canadian Welding Bureau (CWB), the Canadian Standards Association (CSA)
and the American Welding Society (AWS). These standards specify such things as alloy
composition, weld metal strength and toughness, size, type of coating, welding position
and type of current for various types of electrodes. They use a standard code system to
place this information on each electrode. The lettering printed on each electrode indicates
the classification number.
Most of our electrodes are manufactured by American based companies and thus initially
conform to the AWS classification system and are stamped with the AWS numbers.
Electrodes sold in Canada are required to show the CWB/CSA classification system
numbers. Many electrodes sold in Canada will be stamped with both numbering systems.
The two systems use the same code. The only difference is that the Canadian system uses
metric units (megapascals [Mpa]) to designate the tensile strength, while the American
system uses imperial units (psi - pounds per square inch).
The classification for mild steel electrodes is explained as follows (E48018 is used in this
example).
 The letter E designates an electrode. Often the E is dropped or ignored in casual
communication.
 In the CSA system, the first three digits, 480, designate the minimum tensile
strength of the deposited weld metal in the as-welded condition in megapascals
(MPa).
 In the AWS system, the comparable classification number would be E7018. The
first two digits, 70, are used to indicate the tensile strength measured in
1000 pounds per square inch. The minimum tensile strength of this electrode is
70 000 psi. (See Table 6).
Tensile Strength
CSA (MPa)
AWS (psi) x 1000
410
60
480
70
550
80
620
90
690
100
760
110
830
120
Table 6 - Tensile strength classification for CSA and AWS.

30
The second last digit, 1, indicates the position in which the electrode is suitable
for depositing satisfactory welds. In this case, 1 indicates all positions. Figure 24
lists the welding positions indicated by the other digits: 2, 3 and 4. Information
specific to the second last digit is the same for both AWS and CSA
classifications.
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
The last digit, 8, indicates the type of coating on the electrode, the current to be
used with the electrode, the arc characteristics and job application. In this case,
8 indicates the electrode has a low-hydrogen coating, it operates on AC or DCRP
current, it has a smooth arc with medium penetration and it can be used for
dynamic loads. Information specific to the last digit is the same for both AWS
and CSA classifications.
NOTES
The CSA classification system for mild steel electrodes is given in Figure 24.
Figure 24 - CSA W48.1M1991 electrode classification system.
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Objective Six
When you have completed this objective you will be able to:
Select electrodes for specific applications.
Dynamic and Static Loading Considerations
The type of loading that the finished weld is subjected to is an important consideration
when selecting the electrode to be used.
Dynamic Loading
Dynamic loading takes place when a structure is subjected to rapidly changing loads,
reversals of stress, sudden shock and vibration. Some examples of dynamic loading are
crane booms, truck frames, front-end loaders and farm tillage equipment. Figure 25
illustrates a tower crane hoisting a load on a construction site. The crane boom is
subjected to dynamic loading.
Figure 25 - Dynamically loaded structure.
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Static Loading
Static loading is loading that is stationary or relatively unchanging. Some examples of
static loads are base plates, metal storage racks or beams that support building roofs.
Figure 26 illustrates a metal platform that is bolted to the wall and supporting a gas
vaporizer unit. This is an example of static loading because the load is steady.
Figure 26 - Statically loaded structure.
Some mild steel electrodes produce welds that perform poorly when they are subjected to
rapid changes in loading, stress reversals, cyclic loading and fatigue loading conditions.
Generally, welds made with mild steel electrodes that have low ductility and fracture
toughness values will tend to fatigue, crack or shatter under dynamic loading conditions.
Other electrodes produce welds that can stretch, give and bend with the forces similar to
the proverbial oak tree swaying in the wind. Electrodes that can handle dynamic loads
will also handle static loads, but welds made with rods for static loads will fail
prematurely under dynamic loads. Most job applications in the agricultural and industrial
fields will be dynamically loaded. Therefore, you should select electrodes for dynamic
loads.
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Types of Coatings
The four types of coatings (fluxes) used for stick electrodes are:
 mineral (rutile),
 cellulose,
 low hydrogen (basic) and
 iron oxide.
Mineral (Rutile) Electrodes
Mineral electrodes have either a 2, 3 or a 4 in the last digit of their label; for example,
E41012 (E6012), E41013 (E6013), E48014 (E7014 (E48014)), E48024 (E7024). Refer to
Table 7. The name rutile refers to the relatively large amount of titania present in the
flux. These are shallow penetration electrodes, which are easy to use in the flat and
horizontal positions. They strike easily and operate with good arc stability. These
electrodes develop a thick, medium to slow freezing slag, which requires the use of
higher amperages to promote the slag to float up and separate. The puddle is relatively
large and fluid and thus is somewhat difficult to control in the vertical and overhead
positions. Mineral based electrodes are often chosen for work on sheet metal and for
single pass fillet welds in the flat and horizontal positions. The finished weld is bright and
shiny with fine ripples and a flat profile.
Mineral based coatings produce the lowest volume of shielding gases to protect the weld
pool from any type of coating. Therefore, welds deposited using them are susceptible to
porosity. Mineral electrodes also deposit weld metal that is relatively low in toughness
and ductility; thus, the welds produced do not stand up well under a dynamic load.
Cellulose Electrodes
Cellulose electrodes have either a 0 or a 1 as the last digit in their label (for example,
E6010/E41010 or E6011/E41011). Refer to Table 7. The coating contains a large
proportion of cellulose. Cellulose is an organic material that comes from wood pulp.
When it is present in electrode coatings, it has two effects. First, it produces large
volumes of carbon dioxide, carbon monoxide and hydrogen to shield the weld pool.
Welds deposited with these electrodes very seldom contain porosity and have high
ductility. The second effect of cellulose is it creates very deep penetration. As a result of
this deep penetration characteristic, undercutting is possible if proper operating
techniques are not used.
Cellulose electrodes produce a light, fast freezing slag; therefore, the puddle freezes
quickly giving the weld bead a characteristic rough appearance.
Cellulose electrodes are used where deep penetration and sound weld metal is desirable,
such as in the root pass when repair welding a crack in the main frame of an air-seeder.
These electrodes are well suited to multi-pass welding in vertical and overhead positions.
The welds produced stand up well under dynamic loads.
Cellulose electrodes are intended to contain up to seven percent moisture in their coatings
in order to operate properly. If they are stored in a heated electrode oven, they will
become too dry and will be difficult to use. Cellulose coatings liberate large amounts of
hydrogen into the arc and thus, welds made on heavy weldments, alloys and high carbon
steels are prone to hydrogen induced cracking.
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Low Hydrogen (Basic) Electrodes
Low hydrogen electrodes that you will most likely encounter, have an 8 as their last digit
(for example, E7018/E48018 or E7028/E48028). Refer to Table 7. The name basic refers
to the large amount of lime or calcium carbonate that these coatings contain. This type of
coating gives off very little hydrogen during the welding process and, by using high
baking temperatures to reduce the chemically bound water, the weld metal they deposit
can contain very low levels of hydrogen. It is for this reason that this type of electrode is
known as low hydrogen. Low hydrogen electrodes deposit weld metal that is very tough
and ductile enabling the welds to withstand dynamic loads. Penetration of the weld pool
is shallower compared to cellulose rods. There is less carbon dioxide to shield the weld
pool; therefore, low hydrogen rods must be used with a short arc length in order to
prevent porosity.
Certain steels are considered difficult to weld. They include thick components, medium
and high carbon steels as well as alloy steels containing small amounts of chromium,
nickel and molybdenum. When these alloy steels are welded with ordinary electrodes, it
is common for cracks to develop within, under and around the weld bead. It has been
determined this cracking is caused by free hydrogen contaminating the weld metal; thus,
the development of low hydrogen electrodes containing practically no hydrogen bearing
compounds. The coating is mainly lime with no cellulose or moisture present. Rods are
baked to 315°C or more and the welding operator can usually spot these electrodes by the
heat-discoloured ends of the electrodes (brown or blue).
Metals that are prone to cracking still must be carefully preheated and cooled slowly to
prevent cracking due to unequal expansion and contraction.
Conditioning and Storage of Low Hydrogen Electrodes
Low hydrogen electrodes must be kept dry. Electrodes that are exposed to the atmosphere
absorb moisture. During welding, the moisture enters the arc and breaks down into
hydrogen and oxygen. The hydrogen dissolves into the molten pool. During
solidification, hydrogen is thrown out of solution and, under certain conditions, causes
porosity. During cooling of the solid weld, more hydrogen is released as the solubility
falls. Some of this hydrogen stays in the weld and may cause weld cracking. Some of it
diffuses into the parent plate adjacent to the weld (the heat-affected zone) and may cause
cracking in that region.
Porosity can occur throughout the length of the weld, but is more prevalent at the start of
a weld. This start porosity is always a concern when the arc is initially struck because the
gaseous shield of carbon dioxide may not always have time to become fully effective.
Increased moisture content in the coating increases the occurrence of porosity. Tests have
shown that as little as 11/2% moisture in the coating will cause general porosity.
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Low hydrogen electrodes are sold in moisture proof containers. It is advantageous for the
low volume user to purchase electrodes in small containers to minimize the number of
electrodes exposed when the container is opened. Opened electrodes can be stored with a
moisture-absorbing agent in a resealable container. Long term storage of larger amounts
of electrodes is best accomplished in an electrode oven at a temperature above the boiling
point of water (120°C). Only take out only rods that will be used within one hour. It
should be noted that a refrigerator cabinet with a light bulb does not maintain high
enough temperatures for storing low hydrogen electrodes. Electrode storage ovens should
not be used to provide hot lunches because this introduces moisture into the oven, which
can be absorbed by the electrodes. If rods have gathered any moisture, they should be
dried by baking at 315°C for two hours before using (Figure 27).
Figure 27 - Electrode holding oven (rod oven) for low hydrogen electrodes.
Storage of Other Electrodes
Most non-low-hydrogen electrodes require some moisture content in the coating
(5 to 7%). Do not store them in a heated oven. Store them in a loosely covered container
in a shop environment. If more extreme weather conditions are involved, keep the rods in
sealed containers to prevent changes in moisture content.
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Specific Information on Mild Steel Electrodes
Some types of electrodes, for example, those with a 4 or an 8 as their last digit, also
contain iron powder in their coatings. The iron powder is added to increase their
deposition rate. It is melted along with the rest of the flux and adds to the volume of
deposited filler metal. The iron powder also improves arc stability. Table 7 shows this.
Electrode Characteristics
Electrode
E610
E41010
E6011
E41011
E6013
E41013
E7014
E48014
E7018
E48018
E7024
E48024
Power
Supply
DCRP
only
DCRP or
AC
DCRP,
DCSP or
AC
DCRP,
DCSP or
AC
DCRP or
AC
DCSP ,
DCRP or
AC
Tensile
Strength
60 000 psi
410 MPa
60 000 psi
410 MPa
Position
Type of Coating Type of Slag Penetration
All
Cellulose
All
Cellulose
60 000 psi All (best flat
Mineral Rutile
410 MPa or horizontal
70 000 psi All (best flat
Mineral Rutile
480 MPa or horizontal
70 000 psi
All
480 MPa
Low Hydrogen
70 000 psi Flat or
480 MPa Horizontal
Mineral Rutile
Thin, Fast
Freezing
Thin, Fast
Freezing
Medium
Freezing
Heavy,
Slow
Freezing
Medium
Freezing
Heavy,
Slow
Freezing
Job
Application
Deep
Dynamic
Deep
Dynamic
Medium
Static
Shallow
Static
Medium
Dynamic
Shallow
Static
Table 7 - Practical information sheet commonly used for mild steel electrodes.
The following text gives detailed descriptions of individual electrodes.
E6010 (E41010)
E6010 (E41010) is an all position electrode - D.C. (reverse polarity) high cellulose
coating, which produces large volumes of carbon dioxide and water vapour providing the
gaseous shield. The slag is fast freezing, is easily removed when cold and does not
always cover the weld. The puddle freezes quickly so there is a tendency toward rougher
appearing beads that are flat to convex in shape. Since cellulose breaks down easily under
heat (82°C), the use of high amperage settings is not advised. Care must be taken to
provide suitable storage as these rods will not operate to best advantage if too moist or
too dry. For best results, moisture in the coatings should range between 5 - 7%. If rods
are too dry, the end of the rod will fingernail (the coating will burn off to one side) and
pinholes and blisters will occur in the crater. Excess moisture will cause an unstable arc
and high spatter loss. The electrode tends to burn away faster than the coating, giving a
deep cup on the rod end. This promotes deep penetration and narrow beads if a close arc
is held, but may lead to serious undercut if care is not taken.
The deposited metal quality is very good so there is little tendency toward porosity.
Ductility is high, usually ranging from 23 - 35% elongation in 2", while tensile strength
ranges from 60 000 to 70 000 psi (410 to 480 MPa).
This rod is especially recommended for vertical and overhead welding and is excellent
for multiple pass welds in groove joints. It produces welds that are excellent for dynamic
loading.
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E6011 (E41011)
E6011 (E41011) is an all position electrode for use with AC or DC (usually reverse
polarity). Use straight polarity on light gauge plate when less penetration is important. In
this electrode, the cellulose content is lowered and ionizing agents, such as potassium
feldspar or potassium titanate, are added to maintain a smoother arc and to improve the
ease of striking the arc. It is designed to enable the use of alternating current for the same
applications as E6010 (E41010). Physical properties of the welds are as good and often
slightly better than those from E6010 (E41010). The moisture content should range
between 5 - 7%.
E6013 (E41013)
E6013 (E41013) is an AC or DC electrode designed for alternating current. Flux is
mainly rutile and cellulose with ionizing agents added to improve arc stability for AC
welding. High current densities are not recommended because of flux breakdown. Spatter
loss is low and beads are bright, smooth and flat. Slag removes easily. Penetration is
shallow, but with careful slag removal, it may be used for multiple pass welding. The
heavy slag and fluid puddle make vertical and overhead welding difficult. Ductility is
low. These electrodes have good operator appeal and thus, are commonly used to initiate
the welding student to the welding process. Because of the characteristic mechanical
properties of the welds produced, you would be wise to select other electrodes described
here for fabrication and repair of agriculture machinery. Care should be taken to use this
rod only where static loading is encountered and never for dynamic loading.
E7014 (E48014)
E7014 (E48014) electrodes are actually a modification of the E6013 (E41013) class of
electrode through the addition of iron powder. In general, E7014 (E48014) will produce
welds with better physical properties than E6013 (E41013), will stand higher heats, has a
better deposition rate and less spatter loss. Slag removal is considerably easier. Deposits
are clean and smooth and tend to be flat to slightly convex in nature. E7014 (E48014)
may be used with either AC or DC polarity and strikes and restrikes easily with good arc
stability. Penetration is on the shallow side. These electrodes require higher amperages to
promote slag separation from the puddle. The slow freezing puddle makes the puddle
difficult to control in vertical and overhead positions. Choose the E7014 (E48014) for
single pass fillet welds in all positions. Care should be taken to use this rod only where
static loading is encountered and never for dynamic loading.
E7024 (E48024)
With E7024 (E48024) electrodes, performance is good on AC or DC straight or reverse
polarity. The arc is smooth and quiet, spatter loss is low and deposition rates are high.
Beads are slightly convex with a smooth, fine rippled appearance. Slag removal is easy.
Penetration is shallow. Speed of welding is high. These welds are low in ductility. E7024
(E48024) electrodes are recommended for large single pass fillet welds in the horizontal
and flat positions only. Care should be taken to use this rod only where static loading is
encountered and never for dynamic loading.
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E7018 (E48018)
E7018 (E48018) electrodes of this classification are of the low hydrogen type. Electrodes
of this type find use in the welding of steels of the high sulphur and medium carbon alloy
types, which are highly susceptible to hot cracking. They can be used on AC or DC
reverse polarity. Arc stability is reduced on alternating current, but some electrode
companies produce low hydrogen electrodes designed specifically for AC. A short arc is
necessary to prevent porosity. High heats are used. Slag is heavy and seems quite fluid
and is difficult to remove from deep grooves. Use3/32" diameter electrodes for vertical and
overhead positions and rod sizes over 1/8" and over for flat and horizontal applications.
Penetration tends to be medium to shallow and spatter loss is low. Undercutting is
minimal. Welding speeds are good and deposits are clean and have desirable x-ray
soundness. Electrodes of the E7018 (E48018) class are used extensively in the welding of
pressure vessels and piping where corrosion and heat make the use of alloy steels more
practical. The welds produced are excellent for dynamic loading.
E7028 (E48028)
E7028 (E48028) is a low hydrogen electrode containing approximately 50% iron powder
in the coating and designed for high speed flat or horizontal fillet welding on heavy
weldments of mild, low alloy or hard to weld steel. The physical properties of the
deposited metal are remarkably good, including the low temperature impact strength.
Very little hydrogen can be measured in the deposit, which is free from porosity and
easily passes x-ray examinations. Welds on very heavy sections and on critical steels are
free from under-bead cracking. Welding speeds and deposition rates are said to be higher
than is possible with electrodes in the E7024 (E48024) classification.
Stainless Steel Electrodes
Stainless steel electrodes have coatings similar to low hydrogen.
Electrode Selection Simplified
When doing repair, modification or fabrication involving low and medium carbon steel
and alloy steels, it is critical you use the correct filler rod to do the job. For the situations
you will encounter, the rods of choice will be the cellulose based E6010 (E41010) and
E6011 (E41011) and the low-hydrogen E7018 (48018). You will most often use 1/8"
E6010/11 (E481010/11) for tacking and welding on 1/8" and thicker plate. You will use
3
/32" E6010/11 (E481010/11) on light gauge plate. When using low-hydrogen, choose
3
/32" E7018 (E48018) for vertical positions and when welding on thin plate. Choose 1/8"
and larger E7018 (E48018) for flat and horizontal positions on thick plate. The following
considerations will help you to make your selections.
Type of Load
Since most applications you will encounter in the agricultural and industrial field will be
dynamic, you will do well if you use only dynamic electrodes (E6010 (E41010), E6011
(E41011), E7018 (E48018)). If the application is only static, these electrodes will still
function well.
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NOTES
Power Source
If you have a welding machine only capable of outputting AC, use E6011 (E41011) and
E7018 (E48018). All 18s are supposed to work on AC, but some manufacturers produce a
very unstable arc on AC and thus, are difficult to manage. Some companies produce
E7018 (E48018) rods designed specifically for AC and thus, will be safer to use. If you
have a welding machine capable of DC, you are not limited in your choice.
Filler Material Compatible with Parent Material
Choose filler rods that match or exceed the tensile strength, alloy content and other
mechanical properties of the parent material. If the base metal is low carbon or mild steel,
choose rods in the 60 000 psi to 70 000 psi (410 to 480 MPa) range. Higher tensile steel
will require higher tensile rods (such as 80 000 psi (550 MPa) or higher). Medium to high
carbon steel and alloy steels require the use of low-hydrogen electrodes (E7018 (48018),
E8018 (E55018)). Very high carbon steels, high alloys and cast iron require the use of
specific electrodes and specific welding procedures. Consult with a journeyman welder
and your welding supplier for details.
Position
Flat and horizontal positions allow the use of a large fluid puddle. Place the object so the
welding can be done in these positions, whenever possible. Many fillet welds can be done
in large single passes rather than in many small passes. Use 1/8" and larger rods to
maximize the fill rate. Use E7018 (E48018) if you desire a smooth finish.
Vertical and overhead positions require the use of a smaller, fast freezing puddle. 1/8"
E6010 (E41010) and E6011 (E41011) work well for position welding. Choose 3/32" when
using low-hydrogen (E7018/E48018) in these positions.
Joint Type
Deep groove welds require an electrode with an aggressive deep digging arc. Joints with
an open root gap require a fast freezing puddle. Choose E6010 (E41010) or E6011
(E41011) especially for the root pass. For fill and cap passes, single pass fillets and wideopen joints, the less aggressive faster filling E7018 (E48018) is a good option.
Plate Thickness and Mass
Thin and small pieces of metal require the use of low amperages and a small puddle.
Choose small rods (3/32"). Thick plate requires higher currents and a larger puddle.
Choose 1/8" and larger electrodes.
Finish
Low-hydrogen electrodes (E7018/E48018) will create welds with smooth surface finish.
Cellulose based rods (E6010/11 (E41010/11)) leave a rougher surface texture.
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NOTES
Metal Identification
The following are some simple tests you can perform to determine the type of metal you
are dealing with so you can ultimately select the appropriate electrode.
Testing
A quick and fairly accurate test for identifying a metal can be made by the study of the
spark stream produced during grinding. The spark test is used mainly to test for carbon
content in steels and to distinguish between cast steel and cast iron. For best results on
steels, you should compare the spark of the unknown specimen with that of a known
specimen. Make sure you use equal pressure against the grinding wheel and use a dark
background to give good contrast. Most non-ferrous metals such as aluminum,
magnesium and copper alloys will not show any sparks. Two exceptions of non-ferrous
metals that show sparks are nickel and titanium.
Figure 28 is an illustration of the sparks produced by low-carbon steel (also known as
mild steel). The sparks are bright, long, straight and yellowish in colour. There is very
little branching and few carbon bursts.
Figure 28 - Spark test to identify low-carbon steel.
Figure 29 is an illustration of the sparks produced by high-carbon steel. The sparks tend
to burst and branch off more than they do with low-carbon steel. The sparks are a darker
yellow-orange colour and burst nearer to the wheel. Some sparks follow around the
wheel.
Figure 29 - Spark test to identify high-carbon steel.
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NOTES
Figure 30 illustrates the sparks produced by cast iron. The spark stream produces many
bursts that are red coloured near the grinder and orange-yellow further out. The spark
stream is not as long as it is with carbon steels. To produce sparks with cast iron, you
may have to apply considerably more pressure than with carbon steels.
Figure 30 - Spark test to identify cast iron.
Figure 31 is an illustration of the sparks produced by high-speed or cutting steel. The
lines are orange with very little branching and end up in ball-shaped sparks.
Figure 31 - Spark test to identify high-speed steel.
Almost all tool steels contain alloying elements (besides carbon) which affect the spark
stream. The spark stream may not be a reliable indicator of carbon content of high-speed
steels since the effects of the other elements cannot be distinguished from those of
carbon.
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NOTES
File Hardness Tests
Another common method of identifying metals is by determining hardness. A quick
method of determining hardness is to scratch the metal. This gives you a rough indication
of the hardness or lets you compare two different metals. The Rockwell and Brinell
hardness tests are the most common for precise and accurate measures of hardness.
NOTE
On most carbon steels, the Rockwell system uses a conical diamond
penetrator applied on a surface at a specified load. After applying the
load, the Rockwell hardness number is read directly from a gauge that
measures the depth of the indentation. The number on the gauge is
then equated to one of several scales, depending on the type of
penetrator used and the applied load.
Table 8 shows the Rockwell B and C scales. The Brinell hardness tester works on a
similar principle except it measures the diameter of an impression made by a hardened
steel ball on the surface of the test specimen.
A new hand file can be used to determine the approximate hardness of a piece of steel.
Table 8 lists the reaction of the file to certain metals and also provides the Rockwell and
Brinell hardness ratings for the steels.
Using a File to Measure Hardness
File Reaction
Type of Steel
Brinell
Rockwell
B
C
File bites easily into metal.
Low carbon
100
57
File bites into metal with some pressure.
Medium carbon
200
93
File bites into metal with more pressure.
High alloy
300
32
Metal can be filed, but with difficulty.
High carbon
400
43
File will mark metal. Metal almost hard as
file.
Tool steel
500
52
Metal is harder than the file.
Hardened tool steel
600
59
Table 8 - Using a file to measure hardness of steel.
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NOTES
Self-Test
1. Which term describes the voltage output of the machine while welding is being done?
a) arc rectification
b) arc blow
c) arc voltage
d) inductance
2. Electrode negative is:
a) straight polarity.
b) reverse polarity.
c) AC transformer.
d) alternating current.
3. Which term describes a noisy, uncontrollable arc that flares from side to side?
a) arc voltage
b) arc blow
c) inductance
d) resistance
4. Which current flows in one direction only and has either a positive or negative value?
a) direct current
b) alternating current
c) open circuit voltage
d) arc voltage
5. Which term expresses the strength of a current of electricity?
a) amperage
b) voltage
c) electron
d) conductor
6. When no current is flowing in the circuit, but the machine is turned on, you can
measure the:
a) constant current.
b) open circuit voltage.
c) alternating current.
d) volt-amp curve.
7. Which term describes the property of an electrical conductor that opposes the flow of
current?
a) resistance
b) inductance
c) voltage
d) amperage
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8. Which welding machine transforms AC to DC?
a) line transformer
b) transformer rectifier
c) DC generator
d) AC transformer
9. Electrode positive means:
a) straight polarity.
b) reverse polarity.
c) AC transformer.
d) alternating current.
10. How can you change the polarity on an AC generator welding machine?
a) Switch the cables at the machine.
b) Reverse the direction of the motor.
c) Change the polarity taps on the reactor coils.
d) An AC generator has no fixed polarity.
11. Loose ground clamp connections, when using SMAW, may cause:
a) electrical shock.
b) magnetic arc blow.
c) high burn-off rates.
d) arcing at the work clamp.
12. Dynamically loaded structures are subject to:
a) constant pressure.
b) reversals of stress.
c) loads that do not impact.
d) stationary loading conditions.
13. In the AWS classification for SMAW mild steel electrodes, what does the last digit
represent?
a) The type of shielding gas produced by the melting flux.
b) The amount of metallic powder that is added to the coating.
c) The welding position in which the electrode may be satisfactorily operated.
d) The major ingredient in the coating and recommended current for best
results.
14. What do the first two digits in the AWS classification for carbon steel SMAW
electrodes represent?
a) current type and application
b) as-welded minimum tensile strength
c) recommended welding positions
d) iron powder content of the coating in %
15. According to AWS, which number indicates the positions an E7024 can be used in?
a) first number
b) second number
c) third number
d) fourth number
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NOTES
16. The CSA system uses what term to measure tensile strength?
a) kilopascals
b) joules per square metre
c) megapascals
d) watts per square metre
17. What is the difference between an E7018 and an E7028 electrode?
a) E7018 has a lime-type coating; E7028 does not.
b) E7018 can be used in all positions; E7028 cannot.
c) E7018 has metallic powder in the coating; E7028 does not.
d) E7018 is for static loading; E7028 is for dynamic loading.
18. What is one difference between an E7010 electrode and an E7018 electrode?
a) core wire
b) minimum as-welded tensile strength
c) coating
d) recommended welding positions
19. What is one characteristic of an E6010 electrode?
a) deep penetration into the base metal
b) produces a low hydrogen type weld deposit
c) shallow penetration into the base metal
d) wide metal flow and very fluid puddle
20. What is the major difference between the coatings of an E41010 and an E41011
electrode?
a) There is no difference.
b) An E41010 requires moisture but an E41011 does not.
c) An E41010 has arc stabilizers added for AC welding.
d) An E41011 has arc stabilizers added for AC welding.
21. Which electrode has a cellulose coating?
a) E6010
b) E6013
c) E7014 (E48014)
d) E7018
22. What is one purpose of the flux coating on a welding electrode?
a) To promote the formation of oxides and nitrides in the weld puddle.
b) To prevent undercut and arc blow and minimize distortion.
c) To prevent the formation of a gaseous shield around the molten weld metal.
d) To protect the molten weld puddle from atmospheric contamination.
23. Which last digit, in the classification of a SMAW mild steel electrode, describes a
coating that is low-hydrogen?
a) 0
b) 1
c) 4
d) 8
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24. What is one function of the slag produced from electrode coatings?
a) To add more nitrogen and oxygen to the weld.
b) To help maintain the arc and control penetration.
c) To add alloying elements to the weld deposit.
d) To prevent the weld from cooling too rapidly.
NOTES
25. What is the likely effect of using low hydrogen electrodes with a moisture content
that exceeds acceptable limits?
a) The weld metal will probably have porosity and may develop hydrogeninduced cracking.
b) The slag produced will be difficult to remove, resulting in slag inclusions on
subsequent passes.
c) The excess steam rising out of the protective gaseous shield will make it hard
to see the puddle.
d) The deposited weld metal will look too much like the deposit of a cellulosecoated electrode.
26. What is the main purpose for keeping low hydrogen electrodes dry?
a) To assist in producing and maintaining a stable, smooth arc.
b) To minimize the possibility of hydrogen-induced cracking.
c) To increase the electrode's deposition rate.
d) To increase the shelf life of the electrodes in storage.
27. To weld thin materials, you would likely select an electrode with:
a) deep penetration characteristics.
b) a large diameter core wire.
c) a small diameter core wire.
d) a high as-welded tensile strength.
28. Which electrode works best for the root bead on groove welds with an open gap?
a) E41013
b) E48028
c) E41010
d) E48024
29. What is the major advantage of using an E41010 for the root bead and E48018
electrodes for fill passes on one welded joint?
a) The company can save money on the cost of electrodes because E41010
electrodes are cheaper.
b) It is easier on the welding machine if the amperage changes periodically and
E41010 electrodes use lower amperages.
c) It takes advantage of the penetration qualities of the E41010 and the
mechanical properties of the E48018.
d) It will determine if welders can follow specific procedures before they
attempt the B pressure test.
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NOTES
30. Which electrode would be the best choice if the base metal properties were
unknown?
a) E7018
b) E7014 (E48014)
c) E6011
d) E7024
31. What polarity is recommended for:
a) E41010 _____________________________
b) E48018 _____________________________
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Self-Test Answers
1. c) arc voltage
2. a) straight polarity.
3. b) arc blow
4. a) direct current
5. a) amperage
6. b) open circuit voltage.
7. a) resistance
8. b) transformer rectifier
9. b) reverse polarity.
10. d) An AC generator has no fixed polarity.
11. d) arcing at the work clamp.
12. b) reversals of stress.
13. d) The major ingredient in the coating and recommended current for best results.
14. b) as-welded minimum tensile strength
15. c) third number
16. c) megapascals
17. b) E7018 can be used in all positions; E7028 cannot.
18. c) coating
19. a) deep penetration into the base metal
20. d) An E41011 has arc stabilizers added for AC welding.
21. a) E6010
22. d) To protect the molten weld puddle from atmospheric contamination.
23. d) 8
24. d) To prevent the weld from cooling too rapidly.
25. a) The weld metal will probably have porosity and may develop hydrogen-induced
cracking.
26. b) To minimize the possibility of hydrogen-induced cracking.
27. c) a small diameter core wire.
28. c) E41010
29. c) It takes advantage of the penetration qualities of the E41010 and the mechanical
properties of the E48018.
30. a) E7018
31. a) E41010 DCRP only
b) E48018 AC or DCRP
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49
Alberta Apprenticeship
Excellence Through
Training and Experience
Module Number 320102cA
Version 2.2
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