How to Arc Weld
from wikiHow - The How to Manual That You Can EditShielded Metal Arc welding is the process of joining two metal pieces using a flux covered electrode which is melted in an electric arc and becomes a fused part of the pieces being welded. This article will describe the use of flux-coated welding rods and a simple, transformer type cracker box welding machine.
Steps
- Understand the process of
shielded Metal Arc Welding. An electric arc is formed at the tip of
the welding rod when a current passes across an air gap and continues
through the grounded metal which is being welded. Here are some of the
terms and their descriptions used in this article:
- Welding machine. This
is the term used to describe the machine which converts 120-240 volt AC
electricity to welding voltage, typically 20-30 volts AC, but also a
range of DC voltages. It generally consists of a large, heavy
transformer, a voltage regulator circuit, an internal cooling fan, and an
amperage range selector.The term welder applies to the person doing the
welding. A welding machine requires a welder to operate it.
- Leads, or Welding
leads. These are the insulated copper conductors which carry the high
amperage, low voltage electricity to the work piece that is being welded.
- Rod holder, or stinger
is the device on the end of the lead that holds the electrode, which the
person welding uses to accomplish the welding task.
- Ground and ground
clamp. This is the lead that grounds, or completes the electrical
circuit, and specifically, the clamp that is attached to the work to
allow the electricity to pass through the metal being welded.
- Amperage, or amps.
This is an electrical term, used to describe the electrical current
supplied to the electrode.
- DC and reverse
polarity. This is a different configuration used in welding with an
arc/electrode system, which offers more versatility, especially in
overhead welding applications and for use welding certain alloys that do
not weld easily with AC voltages. The welding machine that produces this
current has a rectifier circuit or has the current supplied by a
generator, and is much more expensive than a typical AC welder.
- Electrodes. There are
many specialized welding electrodes, used for specific alloys and types
of metals, such as cast or malleable iron, stainless or chromolly steel,
aluminum, and tempered or high carbon steels. A typical electrode
consists of the wire rod in the center covered with a special coating
(flux)which burns as the arc is maintained, consuming oxygen and
producing carbon dioxide in the weld area to prevent the base metal from
oxidizing or burning away in the arc flame during the welding process.
Here are some common electrodes and their uses:
- E6011 electrodes are
a mild steel electrode with a cellulose fiber coating. The first two
numbers in the electrode identification is the tensile strength,
measured in pounds per square inch times 1,000. Here, the yield of the
electrode would be 60,000 PSI.
- E6010 electrodes are
a reverse polarity electrode, commonly used for welding steam and water
pipes, and are particularly useful for overhead welding, since
the metal holds its position while in a liquid state, being drawn into
the molten weld pool by the flow of the direct current from the electrode
to the workpiece.
- Other specific
purpose E60XX electrodes are available, but since E6011s are
considered a standard, general purpose rod, and E6010s are considered
the standard for reverse polarity DC welding, they will not be covered
in detail in this article.
- E7018 electrodes are low
hydrogenflux coated steel rods, with a high yield tensile strength
of 70,000 PSI. These are often used in assembling structural steel used
in the construction industry, and in other applications where a strong
filler material and higher strength weld is required. Note that,
although these rods provide greater strength, they are less forgiving in
respect to achieving a clean, high-grade weld at incorrect amperages and
with dirty (rusted, painted, or galvanized) steels. These
electrodes are called low hydrogen due to every attempt to lower the
hydrogen content. These electrodes must be stored in an oven with a
temperature between 250ºF and 300ºF. This temperature is above the water
boiling point of 212ºF at sea level. This temperature keeps the moisture
(dew)(H2O) in the air from collecting in the flux.
- Nickel, Castalloy,
Ni-Rod electrodes. These are special rods made for welding cast,
ductile, or malleable iron, and have more yield, to allow for the
expansion and contraction of the iron material being welded.
- Dissimilar metals
rods. These rods are made from a special alloy and give better results
when welding tempered, hardened or alloyed steels.
- Aluminum rods. These
are a more recent technology and allow arc welding aluminum with a
conventional welder, rather than using a special gas-shielded wire feed
welder like a MIG (metal, inert gas) or TIG (tungsten, inert gas)
welding machine, often referred to as heliarc welding, since
helium was the gas used to shield the arc flame while welding. The
official names created by the American Welding Society (AWS)for this arc
type welding are Shielded Metal Arc Welding (stick), Gas Tungsten Arc
Welding (tig)and Gas Metal Arc Welding (mig).
- Electrode sizes.
Electrodes come in a variety of sizes, measured by the diameter of the
metal center of each rod. For mild steel rods, a diameter range of 1/16
inch to 3/8 inch is available, and the size used is determined by the
amperage of the welder, and the thickness of the material being welded.
Each rod performs best at a given amperage range. Selecting the correct
amperage range for a given size rod will depend on the base material and
the desired penetration, so specific amperages will only be covered for
the welding described further in this article.
- Safety equipment. A
critical part of welding safely is having, and knowing how to use, the
correct safety equipment for the job. Here are some typical items that
are required for welding safely.
- Welding shield
(hood). This is the mask which is worn to protect the person welding
from the bright flash of the arc, and from sparks being thrown during
welding. Standard arc welding lenses are tinted very darkly, since
exposure to the arc flash can cause flash burns to the retina of the
eye. A level 10 darkness is the minimum for arc welding. Welding hoods
with a flip up lens was once preferred, as the dark lens can be
lifted up, and a separate clear glass lens will protect the welder from
bits of slag while the weld is chipped. The newer self darkening
welding shields are the most desirable welding shield now sold. These
welding shield lens are very light colored for grinding and torch
cutting. When an arc is struck the automatic self darkening lens will
change to a preset #10 shade. Even newer on the market are the variable
shade automatic self darkening lens.
- Welding gloves. These
are special, insulated leather gloves that reach about 6 inches above
the wrists, and protect the hands and lower arms of the welder (the
person welding). They also provide limited protection from accidental
shock if the person welding comes into contact with the electrode
accidentally.
- Welding leathers.
This is an apron like leather jacket that covers the shoulders and chest
of the welder, used for overhead work where sparks might ignite the
welders clothing, or cause burns.
- Work boots. The person
welding should wear at least a 6 inch lace-up type boot to prevent
sparks and hot slag from burning his feet. These boots should have
insulating soles made from a material which does not melt or burn
easily.
- Learn the steps for creating
a successful weld. Welding is more than dragging a welding rod across a
piece of steel and gluing it to another one. The process begins with
properly fitting and securing the work pieces, or metal to be
welded, together. For thicker pieces, you may want to grind a bevel so
subsequent beads can be placed in the groove to fill it completely with a
solid weld. Here are the basic steps for completing a simple weld.
- Strike the arc. This
is the process of creating an electric arc between the electrode
and the workpiece. If the electrode simply allows the current to pass
directly into the grounded work piece, there will not be enough heat
produced to melt and fuse metal together.
- Move the arc to create
a bead. The bead is the metal from the melting electrode flowing
together with molten metal from the base metal to fill the space between
the pieces being joined by welding.
- Shape the weld bead.
This is done by weaving the arc back and forth across the weld path
either in a zig zag or figure 8 motion so the metal spreads to the width
that you want your finished weld bead to be.
- Chip and brush the
weld between passes. Each time you complete a pass, or trip from
one end to the other of your weld, you need to remove the slag, or
the melted electrode flux material, from the surface of the weld bead so
only clean molten metal will be filling the weld on the subsequent pass.
- Gather the tools and
materials you will need to begin welding. This means the welding machine,
electrodes, cables and clamps, and the metal to be welded.
- Set up a safe work area,
preferably with a table constructed of steel or other non-flammable
material. For practice, a few pieces of mild steel, at least 3/16 inch
thick will work.
- Prepare the metal to be
welded. If the metal consists of two pieces that are to be joined in the
welding process, you may need to prep, or weld prep them, by
grinding a beveled edge on the sides that are to be joined. This allows
for sufficient penetration of the weld arc to melt both sides to a
molten state so the filler metal bonds through the sectional thickness of
the metal. At the least, you should remove any paint, grease, rust, or
other contaminants so you are working with a clean pool of molten metal as
you weld.
- Attach clamps to hold your
metal pieces together, if need. Locking type pliers, "C" clamps,
a vice, or spring loader clamps will usually work. For special projects,
you may find you will have to adapt different techniques to secure the
work pieces until they are joined.
- Attach the ground clamp to
the larger piece of stock that is being welded. Make sure there is a clean
location so that the electrical circuit can be completed with minimal
resistance at the ground location. Again, rust or paint will interfere
with the grounding of your work piece, making it difficult to create an
arc when you begin welding.
- Select the correct rod and
amperage range for the work you are attempting. As an example, 1/4 inch
plate steel can be welded effectively using an E6011, 1/8 inch electrode,
at between 80-100 amps. Place the electrode in the electrode holder
(henceforth referred to as the stinger) making sure the conductive
material of the stinger clamp is on the clean metal at the end of the
electrode.
- Turn on your welding machine.
You should hear a humming sound from the transformer. The sound of the
cooling fan running may or may not be heard. Some welding machine fans
only operate when the machine requires cooling. If you do not, you may
need to check the circuit that is supplying your power, and the breakers
in the panel box. Welding machines require a considerable amount of power
to operate, often a special circuit rated at 60 amps or more at 240 volts.
- Hold the stinger in your
dominant hand by the insulated handle, with the rod in a position so that
striking the tip of it against the plate you are welding will be as
natural a movement as possible. Hold your welding shield up just high
enough so you can see to move the electrode to within a few inches of the
workpiece, ready to flip in down to protect your eyes. You may want to
practice tapping the electrode against the weld metal to get the feel
of it before turning the power on, but never strike an electric arc
without protecting your eyes.
- Select the point where you
wish to begin your weld. Position the tip of the rod close to it, then drop
the welding hood into place. You want to tap the tip of the
electrode against the metal to complete the electrical circuit, then
instantaneously pull it back a little bit, to create an electric arc between
the electrode tip and the metal being welded. Another way to strike an arc
is like striking a match. This arc gap, or airspace, creates a great deal
of resistance in the electrical circuit, which is what produces the arc
flame or plasma and heat needed to liquefy the electrode and the metal
adjacent to the weld area.
- Strike the electrode against
the surface of the metal, pulling it back slightly when you see an
electric arc occur. This takes a great deal of practice, since different
electrode diameters and welding amperages require a different gap between
the tip of the electrode and the work piece, but if you can hold the gap
steady, a continuous electric arc will occur from the electrode to the
work piece. Typically, the arc gap should be no greater than the electrode
diameter. Practice steadying the arc by holding the electrode about 1/8 to
3/16 of an inch from the work piece, then begin moving along the path you
want to weld. As you move the electrode, the metal will be melting away,
filling the pool of molten metal and building your weld.
- Practice traveling across the
path of your weld with the electrode until you can keep a consistent arc,
moving at a consistent speed, and in line with the path you want to weld.
When you have mastered controlling the arc, you will begin to practice
laying, or building up the weld bead. This is the deposit of metal that
joins the two pieces that you are welding together. The technique you use
for laying your bead will depend on the width of the gap (if there is one)
you are filling, and the depth you want the weld bead to penetrate. The
slower you move the electrode, the deeper the weld will go into the metal
work pieces, and for making a wide path, the more you zig zag or weave the
electrodes tip, the wider the bead you will lay up.
- Keep the arc established as
you move along the weld you are making. If the electrode grounds to the
metal and becomes stuck, jerk the stinger to break the rod free either
from the stinger clamp or the weld metal. If the arc is lost because you
move the electrode too far from the metals surface, stop the process and
clean the slag from the spot you are welding so you re-strike the arc to
continue, there will be no slag in the weld area to contaminate the new
weld you are beginning from the place the arc was lost or broken. Never
lay a new bead over existing slag, as this material will melt in the arc
plasma and bubble through the new layer of metal you are placing,
resulting in a weak and dirty weld.
- Practice moving the electrode
in a sweeping motion to create a wider bead. This will allow you to
fill more of the weld in a single pass, leaving a cleaner and more sound
weld. The electrode is moved in a sideways motion as it is drawn along the
weld path, either in a zig-zag, curved, or figure eight motion.
- Adjust your welders output
amperage to suit the material you are welding and the desired penetration
of the arc. If you find the finished weld bead is pitted, with deep
cratering at the beads edges, or the adjacent metal is simply melted or
burned away, reduce the amperage incrementally until the condition is
corrected. If, on the other hand, you have difficulty striking or
maintaining an arc, you may need to increase the amperage.
- Clean your finished weld.
After you have finished welding, you may want to remove the slag and clean
up your weld, either to allow paint to bond better, or simply for cosmetic
reasons. Chip off the slag and wire brush the weld to remove any foreign
material and remaining slag. If the surface needs to be flat to allow
fitting the piece you have welded to another piece, use an angle grinder
to remove the top, or high portion of the bead. A clean weld, particularly
after grinding flat, is easier to examine to see if pitting, puddling, or
other defects have occurred while welding.
- Paint your weld with a
suitable rust-preventative primer to protect it from corrosion. Freshly
welded metal will corrode rather quickly if exposed to the elements, since
the actual base metal is exposed directly to moisture.
Video
Tips
- Some people listen to
the sounds produced by the electric arc to judge the quality of the weld.
Popping and snapping sounds may indicate either inconsistent arc gap or
improper amperage.
- When joining workpieces too
large to effectively clamp, tack the pieces together with small
welds at intervals to prevent the pieces from shifting.
Warnings
- Avoid breathing fumes
produced from the welding process. This especially applies to galvanized
or plated metals, and those metals which have been painted with metal oxide
primers.
- Arc welding machines utilize
a high-amperage electric current which is extremely dangerous, so handle
the cables and stinger with care. Never weld in wet conditions or on wet
material without proper training.
- Metal remains hot for a long
period of time after the weld is complete, so keep pets and children out
of the work area until all materials have cooled.
- Inspect cables and
connections often to decrease the possibility of accidental electrical
shock.
- The bright light from an
electric arc can cause burns similar to a sun burn, so wear long sleeved
shirts and long pants to reduce exposure.
- See link in citations, below
for specific warnings and precautions.
- Protect yourself from
flashburns by covering your skin with gloves, a face mask, and sleeves,
dependent upon the area being covered.
Things You Will Need
- Welding machine, with leads,
clamps, and electrodes
- Tools for preparing and
cleaning welds, including a chipping hammer, wire brush, and an angle
grinder
- Safety equipment
Related wikiHows
Sources and Citations
- Welding machine. This
is the term used to describe the machine which converts 120-240 volt AC
electricity to welding voltage, typically 20-30 volts AC, but also a
range of DC voltages. It generally consists of a large, heavy
transformer, a voltage regulator circuit, an internal cooling fan, and an
amperage range selector.The term welder applies to the person doing the
welding. A welding machine requires a welder to operate it.
- Leads, or Welding
leads. These are the insulated copper conductors which carry the high
amperage, low voltage electricity to the work piece that is being welded.
- Rod holder, or stinger
is the device on the end of the lead that holds the electrode, which the
person welding uses to accomplish the welding task.
- Ground and ground
clamp. This is the lead that grounds, or completes the electrical
circuit, and specifically, the clamp that is attached to the work to
allow the electricity to pass through the metal being welded.
- Amperage, or amps.
This is an electrical term, used to describe the electrical current
supplied to the electrode.
- DC and reverse
polarity. This is a different configuration used in welding with an
arc/electrode system, which offers more versatility, especially in
overhead welding applications and for use welding certain alloys that do
not weld easily with AC voltages. The welding machine that produces this
current has a rectifier circuit or has the current supplied by a
generator, and is much more expensive than a typical AC welder.
- Electrodes. There are
many specialized welding electrodes, used for specific alloys and types
of metals, such as cast or malleable iron, stainless or chromolly steel,
aluminum, and tempered or high carbon steels. A typical electrode
consists of the wire rod in the center covered with a special coating
(flux)which burns as the arc is maintained, consuming oxygen and
producing carbon dioxide in the weld area to prevent the base metal from
oxidizing or burning away in the arc flame during the welding process.
Here are some common electrodes and their uses:
- E6011 electrodes are
a mild steel electrode with a cellulose fiber coating. The first two
numbers in the electrode identification is the tensile strength,
measured in pounds per square inch times 1,000. Here, the yield of the
electrode would be 60,000 PSI.
- E6010 electrodes are
a reverse polarity electrode, commonly used for welding steam and water
pipes, and are particularly useful for overhead welding, since
the metal holds its position while in a liquid state, being drawn into
the molten weld pool by the flow of the direct current from the electrode
to the workpiece.
- Other specific
purpose E60XX electrodes are available, but since E6011s are
considered a standard, general purpose rod, and E6010s are considered
the standard for reverse polarity DC welding, they will not be covered
in detail in this article.
- E7018 electrodes are low
hydrogenflux coated steel rods, with a high yield tensile strength
of 70,000 PSI. These are often used in assembling structural steel used
in the construction industry, and in other applications where a strong
filler material and higher strength weld is required. Note that,
although these rods provide greater strength, they are less forgiving in
respect to achieving a clean, high-grade weld at incorrect amperages and
with dirty (rusted, painted, or galvanized) steels. These
electrodes are called low hydrogen due to every attempt to lower the
hydrogen content. These electrodes must be stored in an oven with a
temperature between 250ºF and 300ºF. This temperature is above the water
boiling point of 212ºF at sea level. This temperature keeps the moisture
(dew)(H2O) in the air from collecting in the flux.
- Nickel, Castalloy,
Ni-Rod electrodes. These are special rods made for welding cast,
ductile, or malleable iron, and have more yield, to allow for the
expansion and contraction of the iron material being welded.
- Dissimilar metals
rods. These rods are made from a special alloy and give better results
when welding tempered, hardened or alloyed steels.
- Aluminum rods. These
are a more recent technology and allow arc welding aluminum with a
conventional welder, rather than using a special gas-shielded wire feed
welder like a MIG (metal, inert gas) or TIG (tungsten, inert gas)
welding machine, often referred to as heliarc welding, since
helium was the gas used to shield the arc flame while welding. The
official names created by the American Welding Society (AWS)for this arc
type welding are Shielded Metal Arc Welding (stick), Gas Tungsten Arc
Welding (tig)and Gas Metal Arc Welding (mig).
- Electrode sizes.
Electrodes come in a variety of sizes, measured by the diameter of the
metal center of each rod. For mild steel rods, a diameter range of 1/16
inch to 3/8 inch is available, and the size used is determined by the
amperage of the welder, and the thickness of the material being welded.
Each rod performs best at a given amperage range. Selecting the correct
amperage range for a given size rod will depend on the base material and
the desired penetration, so specific amperages will only be covered for
the welding described further in this article.
- Safety equipment. A
critical part of welding safely is having, and knowing how to use, the
correct safety equipment for the job. Here are some typical items that
are required for welding safely.
- Welding shield
(hood). This is the mask which is worn to protect the person welding
from the bright flash of the arc, and from sparks being thrown during
welding. Standard arc welding lenses are tinted very darkly, since
exposure to the arc flash can cause flash burns to the retina of the
eye. A level 10 darkness is the minimum for arc welding. Welding hoods
with a flip up lens was once preferred, as the dark lens can be
lifted up, and a separate clear glass lens will protect the welder from
bits of slag while the weld is chipped. The newer self darkening
welding shields are the most desirable welding shield now sold. These
welding shield lens are very light colored for grinding and torch
cutting. When an arc is struck the automatic self darkening lens will
change to a preset #10 shade. Even newer on the market are the variable
shade automatic self darkening lens.
- Welding gloves. These
are special, insulated leather gloves that reach about 6 inches above
the wrists, and protect the hands and lower arms of the welder (the
person welding). They also provide limited protection from accidental
shock if the person welding comes into contact with the electrode
accidentally.
- Welding leathers.
This is an apron like leather jacket that covers the shoulders and chest
of the welder, used for overhead work where sparks might ignite the
welders clothing, or cause burns.
- Work boots. The person
welding should wear at least a 6 inch lace-up type boot to prevent
sparks and hot slag from burning his feet. These boots should have
insulating soles made from a material which does not melt or burn
easily.
- Strike the arc. This
is the process of creating an electric arc between the electrode
and the workpiece. If the electrode simply allows the current to pass
directly into the grounded work piece, there will not be enough heat
produced to melt and fuse metal together.
- Move the arc to create
a bead. The bead is the metal from the melting electrode flowing
together with molten metal from the base metal to fill the space between
the pieces being joined by welding.
- Shape the weld bead.
This is done by weaving the arc back and forth across the weld path
either in a zig zag or figure 8 motion so the metal spreads to the width
that you want your finished weld bead to be.
- Chip and brush the
weld between passes. Each time you complete a pass, or trip from
one end to the other of your weld, you need to remove the slag, or
the melted electrode flux material, from the surface of the weld bead so
only clean molten metal will be filling the weld on the subsequent pass.
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