Lincoln Electric LTW2 User Manual
“LEARNING TO STICK WELD”
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LTW2
“APRENDIENDO PALILLO SOLDAR”
“ APPRENTISSAGE DE BÂTON SOUDURE ”
May, 2009
Safety Depends on You
Lincoln arc welding and cutting equipment
is designed and built with safety in mind.
However, your overall safety can be
increased by proper installation ... and
thoughtful operation on your part. DO NOT
INSTALL, OPERATE OR REPAIR THIS
EQUIPMENT WITHOUT READING THE
OPERATORS MANUAL WHICH IS PRO-
VIDED WITH YOUR MACHINE AND THE
SAFETY PRECAUTIONS CONTAINED
THROUGHOUT. And, most importantly,
think before you act and be careful.
SOUDURE À ARC ÉLECTRIQUE ET COMMANDES DE PUISSANCE
ELECTRODE CABLE
CABLE DEL ELECTRODO
CÂBLE D'ÉLECTRODE
ELECTRODE HOLDER
SOSTENEDOR DE ELECTRODO
PORTE-ÉLECTRODE
SOLDADURA AL ARCO Y CONTROLES DE ENERGÍA
ELECTRODE
ELECTRODO
ÉLECTRODE
La seguridad depende de usted
El equipo de soldadura por arco y corte de
Lincoln está diseñado y construido teniendo
en mente la seguridad. Sin embargo, la
seguridad general puede ser mejor si instala
y opera la máquina adecuadamente.
Lo más importante, piense antes de actuar
y tenga cuidado.
ARC WELDING AND POWER CONTROLS
WORK CABLE
CABLE DEL TRABAJO
CÂBLE DE TRAVAIL
La sécurité dépend de vous
Le matériel de soudage et de coupage à
l'arc Lincoln est conçu et construit en tenant
compte de la sécurité. Toutefois, la sécurité
en général peut être accrue grâce à une
bonne installation... et à la plus grande prudence de votre part.
NN''AACCTTIIOONNNNEEZZ PPAASS OOUU NNEE RRÉÉPPAARREERR PPAAS
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dessus tout, réfléchissez avant d'agir et
exercez la plus grande prudence.
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Et, par
ARC
ARCO
ARC
WORKPIECE
PEDAZO DEL TRABAJO
TRAVAIL MORCEAU
WORK CLAMP
ABRAZADERA DEL TRABAJO
BRIDE DE TRAVAIL
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1
Learn to Stick Weld .......................................................................................................2
Arc Welding Circuit....................................................................................................2
What Happens in the Arc ..........................................................................................2
Correct Welding Position...........................................................................................3
Correct Way to Strike an Arc ....................................................................................3
Correct Arc Length ....................................................................................................3
Practice .....................................................................................................................4
Common Metals..................................................................................................4
Joint Types and Positions.................................................................................5
Butt Joint...........................................................................................................5
Penetration .......................................................................................................5
Fillet Joint..........................................................................................................5
Multi Pass Welds ................................................................................................6
Welding in the Vertical Position ..........................................................................6
Vertical-Up Welding ............................................................................................6
Vertical-Down Welding .......................................................................................6
TABLE OF CONTENTS
Page
1
Overhead Welding ..............................................................................................7
Welding Sheet Metal...........................................................................................7
Hardfacing ..........................................................................................................7
How to hardface the Sharp Edge........................................................................7
Hardfacing of Idler and Roller .............................................................................8
Welding Cast Iron ...............................................................................................8
Cast Iron Plate Preparation ................................................................................9
2
LEARNING TO STICK WELD
2
LEARNING TO STICK WELD
The serviceability of a product or structure utilizing this type of information is and must be the
sole responsibility of the builder/user. Many variables beyond the control of The Lincoln Electric
Company affect the results obtained in applying
this type of information. These variables include,
but are not limited to, welding procedure, plate
chemistry and temperature, weldment design, fabrication methods and service requirements.
No one can learn to weld simply by reading about it.
Skill comes only with practice. The following pages
will help the inexperienced welder to understand
welding and develop his skill. For more detailed information order a copy of (“New Lessons in Arc Welding”
available from the James F. Lincoln Foundation).
The Arc-Welding Circuit
The operator’s knowledge of arc welding must go
beyond the arc itself. He must know how to control the
arc, and this requires a knowledge of the welding circuit and the equipment that provides the electric current used in the arc. Figure 1 is a diagram of the welding circuit. The circuit begins where the electrode
cable is attached to the welding machine and ends
where the work cable is attached to the welding
machine. Current flows through the electrode cable to
the electrode holder, through the holder to the electrode and across the arc. On the work side of the arc,
the current flows through base metal to the work cable
and back to the welding machine. The circuit must be
complete for the current to flow. To weld, the work
clamp must be tightly connected to clean base metal.
Remove paint, rust, etc. as necessary to get a good
connection. Connect the work clamp as close as possible to the area you wish to weld. Avoid allowing the
welding circuit to pass through hinges, bearings, electronic components or similar devices that can be damaged.
A gap is made in the welding circuit (see Figure 1) by
holding the tip of the electrode 1/16-1/8” away from
the work or base metal being welded. The electric arc
is established in this gap and is held and moved along
the joint to be welded, melting the metal as it is
moved.
Arc welding is a manual skill requiring a steady hand,
good physical condition, and good eyesight. The operator controls the welding arc and, therefore, the quality of the weld made .
To electrical
(earth) ground.
FIGURE 1—The welding circuit for Shielded Metal
Arc Welding(SMAW)
What Happens in the Arc?
Figure 2 illustrates the action that takes place in the
electric arc. It closely resembles what is actually seen
during welding.
The “arc stream’’ is seen in the middle of the picture.
This is the electric arc created by the electric current
flowing through the space between the end of the
electrode and the work. The temperature of this arc is
about 6000°F. (3315°C.), which is more than enough
to melt metal. The arc is very bright, as well as hot,
and cannot be looked at with the naked eye without
risking painful injury. The very dark lens, specifically
designed for arc welding, must be used with the hand
or face shield whenever viewing the arc.
.
This arc-welding circuit has a voltage output of up to
79 volts which can shock.
The electric arc is made between the work and the tip
end of a small metal wire, the electrode, which is
clamped in a holder and the holder is held by the
welder.
WARNING
ELECTRIC SHOCK can kill.
Carefully review the ARC WELDING
SAFETY PRECAUTIONS at the beginning
of your Operator’s Manual.
------------------------------------------------------------------------------------------
The arc melts the base metal and actually digs into it,
much as the water through a nozzle on a garden hose
digs into the earth. The molten metal forms a molten
pool or crater and tends to flow away from the arc. As
it moves away from the arc, it cools and solidifies. A
slag forms on top of the weld to protect it during cooling.
FIGURE 2—The welding arc.
3
The function of the covered electrode is much more
than simply to carry current to the arc. The electrode
is composed of a core of metal wire around which has
been extruded and baked a chemical covering. The
core wire melts in the arc and tiny droplets of molten
metal shoot across the arc into the molten pool. The
electrode provides additional filler metal for the joint
to fill the groove or gap between the two pieces of the
base metal. The covering also melts or burns in the
arc. It has several functions. It makes the arc steadier, provides a shield of smoke-like gas around the
arc to keep oxygen and nitrogen in the air away from
the molten metal, and provides a flux for the molten
pool. The flux picks up impurities and forms the protective slag. The principal differences between various types of electrodes are in their coatings. By varying the coating, it is possible to greatly alter the operating characteristics of electrodes. By understanding
the differences in the various coatings, you will gain a
better understanding of selecting the best electrode
for the job you have at hand. In selecting an electrode
you should consider:
1. The type of deposit you want, e.g. mild steel, stainless, low alloy, hardfacing.
2. The thickness of the plate you want to weld.
3. The position it must be welded in (downhand, out
of position).
4. The surface condition of the metal to be welded.
5. Your ability to handle and obtain the desired electrode.
Four simple manipulations are of prime importance.
Without complete mastery of these four, further welding is more or less futile. With complete mastery of
the four, welding will be easy.
1. The Correct Welding Position
Beginners will find it easier to learn how to control
the welding arc using the two-handed technique
shown below. This requires the use of a headshield.
LEARNING TO STICK WELD
3
Hold the electrode at a slight angle as shown.
WARNING
ARC RAYS can burn eyes and skin.
When using an open arc process, it
Is necessary to use correct eye,
head and body protection.
Protect yourself and others, read
“ARC RAYS can burn” at the front
of the Operator’s Manual supplied
with the welder.
-----------------------------------------------------------------------
2. The Correct Way to Strike an Arc
Be sure the work clamp makes good electrical contact to the work.
Lower your headshield or hold the hand shield in
front of your face. Scratch the electrode slowly over
the metal and you will see sparks flying. While
scratching, lift the electrode 1/8" (3.2mm) and the
arc is established.
NOTE: If you stop moving the electrode while
scratching, the electrode will stick.
NOTE: Most beginners try to strike the arc by a fast
jabbing motion down on the plate. Result:
They either stick or their motion is so fast
that they break the arc immediately.
3. The Correct Arc Length
a. Hold the electrode holder in your right hand.
b. Touch your left hand to the underside of your
right.
c. Put the left elbow against your left side.
(For welding left-handed it is the opposite.)
If you are using a hand shield, hold the electrode
holder in your right hand and the hand shield in
your left. (For welding left-handed it is the opposite.)
Whenever possible, weld from left to right (if righthanded). This enables you to see clearly what you
are doing.
The arc length is the distance from the tip of the
electrode core wire to the base metal.
Once the arc has been established, maintaining the
correct arc length becomes extremely important.
The arc should be short, approximately 1/16 to 1/8"
(1.6 to 3.2mm) long. As the electrode burns off the
electrode must be fed to the work to maintain correct arc length.
The easiest way to tell whether the arc has the correct length is by listening to its sound. A nice, short
arc has a distinctive, “crackling” sound, very much
like eggs frying in a pan. The incorrect, long arc has
a hollow, blowing or hissing sound.
4
LEARNING TO STICK WELD
4
4. The Correct Welding Speed
The important thing to watch while welding is the
puddle of molten metal right behind the arc. Do
NOT watch the arc itself. It is the appearance of the
puddle and the ridge where the molten puddle
solidifies that indicate correct welding speed. The
ridge should be approximately 3/8" (9.5mm) behind
the electrode.
Most beginners tend to weld too fast, resulting in a
thin, uneven, “wormy” looking bead. They are not
watching the molten metal.
IMPORTANT: For general welding it is not necessary to weave the arc; neither forwards and backwards nor sideways. Weld along at a steady pace.
You will find it easier.
NOTE: When welding on thin plate, you will find
that you will have to increase the welding speed,
whereas when welding on heavy plate, it is necessary to go more slowly in order to get good penetration.
PRACTICE
The best way of getting practice in the four skills that
enable you to maintain:
1. Correct Welding Position
2. Correct Way To Strike An Arc
3. Correct Arc Length
4. Correct Welding Speed
is to spend a little more time on the following exercise.
3. When you are sure that you can hold a short, crackling arc, start moving. Look at the molten puddle
constantly, and look for the ridge where the metal
solidifies.
4. Run beads on a flat plate. Run them parallel to the
top edge (the edge farthest away from you). This
gives you practice in running straight welds, and
also, it gives you an easy way to check your
progress. The 10th weld will look considerably better than the first weld. By constantly checking on
your mistakes and your progress, welding will soon
be a matter of routine.
Common Metals
Most metals found around the farm or small shop are
low carbon steel, sometimes referred to as mild steel.
Typical items made with this type of steel include most
sheet metal, plate, pipe and rolled shapes such as
channels, angle irons and “I’’ beams. This type of
steel can usually be easily welded without special precautions. Some steel, however, contains higher carbon. Typical applications include wear plates, axles,
connecting rods, shafts, plowshares and scraper
blades. These higher carbon steels can be welded
successfully in most cases; however, care must be
taken to follow proper procedures, including preheating the metal to be welded and, in some cases, carefully controlling the temperature during and after the
welding process. For further information on identifying
various types of steels and other metals, and for proper procedures for welding them, we again suggest you
purchase a copy of (“New Lessons in Arc Welding”
available from the James F. Lincoln arc welding foundation).
Regardless of the type of metal being welded, it is
important in order to get a quality weld that it be free
of oil, paint, rust or other contaminants.
Use the following:
Mild Steel . . . . . . .Plate 3/16" (4.8mm) or heavier
Electrode . . . . . . . .1/8" (3.2mm) Fleetweld® 180
Current Setting . . . . . . . .105 Amps AC
or 95 Amps DC(+)
Do the following:
1. Learn to strike the arc by scratching the electrode
over the plate. Be sure the angle of the electrode is
correct. If you have a headshield use both hands.
2. When you can strike an arc without sticking, practice the correct arc length. Learn to distinguish it by
its sound.
5
LEARNING TO STICK WELD
5
JOINT TYPES AND POSITIONS
Five types of welding joints are: Butt joint, Fillet joint,
Lap joint, Edge joint and Corner joint. See Figure 3.
Of these, the Butt Joint and Fillet Joint are the two
most common welds.
FIGURE 3
Butt joint Lap joint
Edge joint Fillet joint Corner joint
Butt Joints
Penetration
Unless a weld penetrates close to 100%, a Butt Joint
will be weaker than the material welded together.
In this example, the total weld is only 1/2” (12.5mm)
the thickness of the material; thus the weld is only
approximately half as strong as the metal.
In this example, the joint has been flame beveled or
ground prior to welding so that 100% penetration
could be achieved. The weld, if properly made, is as
strong or stronger than the original metal.
Place two plates side by side, leaving 1/16” (1.6mm)
(for thin metal) to 1/8” (3.2mm) (for heavy metal)
space between them in order to get deep penetration.
Securely clamp or tack weld the plates at both ends,
otherwise the heat will cause the plates to move apart.
See Figure 4.
FIGURE 4
Now weld the two plates together. Weld from left to
right (if right handed). Point the Stick electrode
between the two plates, keeping the Electrode Holder
tilted in the direction of travel.
Fillet Joints
When welding a Fillet Joint, it is very important to hold
the electrode at a 45° angle between the two sides, or
the metal will not distribute itself evenly.
To make it easy to get the 45° angle, it is best to put
the electrode in the holder at a 45° angle, as shown:
Weld Direction
Watch the molten metal to be sure it distributes itself
evenly on both edges and in between the plates. This
is referred to as the “pull technique”. On thin gauge
sheet metal, use the “push technique”.
6
Multiple Pass Welds
Make multiple pass horizontal fillet joints as shown in
the sketch. Put the first bead in the corner with fairly
high current. Hold the electrode angle needed to
deposit the filler beads as shown putting the final bead
against the vertical plate.
LEARNING TO STICK WELD
6
5. The upward motion of the arc is caused by a very
slight wrist motion. Most definitely, the arm must not
move in and out, as this makes the entire process
very complicated and difficult to learn.
6. If the upward motion of the arc is done correctly
with a wrist motion, the arc will automatically
become a long arc that deposits little or no metal.
(See drawing.)
7. During this entire process the ONLY thing to watch
is the molten metal. As soon as it has solidified, the
arc is SLOWLY brought back, and another few
drops of metal are deposited. DO NOT FOLLOW
THE UP AND DOWN MOVEMENT OF THE ARC
WITH THE EYES. KEEP THEM ON THE MOLTEN
METAL.
Welding in the Vertical Position
Welding in the vertical position can be done either vertical-up or vertical-down. Vertical-up is used whenever
a large, strong weld is desired. Vertical-down is used
primarily on sheet metal for fast, low penetrating
welds.
Vertical-Up Welding
The problem, when welding vertical-up, is to put the
molten metal where it is wanted and make it stay
there. If too much molten metal is deposited, gravity
will pull it downwards and make it “drip.’’ Therefore a
certain technique has to be followed:
1. Use 1/8" (3.2mm) at 90-105 amps or 3/32" (2.4mm)
at 60 amps Fleetweld® 180 electrode.
2. When welding, the electrode should be kept horizontal or pointing slightly upwards. (See drawing.)
8. When the arc is brought back to the now solidified
puddle, IT MUST BE SHORT, otherwise no metal
will be deposited, the puddle will melt again, and it
will “drip.”
9. It is important to realize that the entire process consists of SLOW, DELIBERATE movements. There
are no fast motions.
Vertical-Down Welding
Vertical-down welds are applied at a fast pace. These
welds are therefore shallow and narrow, and as such
are excellent for sheet metal. Do not use the verticaldown technique on heavy metal. The welds will not be
strong enough.
1. Use 1/8” (3.2mm) or 3/32" (2.4mm) Fleetweld® 180
electrode.
2. On thin metal, use 60-75 amps. (14 ga 75 amps —
16 ga 60 amps.)
3. Hold the electrode in a 30-45° angle with the tip of
the electrode pointing upwards.
4. Hold a VERY SHORT arc, but do
not let the electrode touch the
metal.
5. An up and down whipping motion
will help prevent burn-through on
very thin plate.
6. Watch the molten metal carefully.
3. The arc is struck and metal deposited at the bottom
of the two pieces to be welded together.
4. Before too much molten metal is deposited, the arc
is SLOWLY moved 1/2”-3/4" (12.5-19mm) upwards.
This takes the heat away from the molten puddle,
which solidifies. (If the arc is not taken away soon
enough, too much metal will be deposited, and it
will “drip.’’)
The important thing is to continue lowering the entire
arm as the weld is made so the angle of the electrode
does not change. Move the electrode so fast that the
slag does not catch up with the arc. Vertical-down
welding gives thin, shallow welds. It should not be
used on heavy material where large welds are
required.
7
Overhead Welding
Various techniques are used for overhead welding.
However, in the interest of simplicity for the inexperienced welder the following technique will probably
take care of most of his needs for overhead welding:
1. Use 1/8" (3.2mm) at 90-105 amps or 3/32" (2.4mm)
at 60 amps Fleetweld® 180 electrode.
2. Put the electrode in the holder so it sticks straight
out.
3. Hold the electrode at an angle approximately 30°
off vertical, both seen from the side and seen from
the end.
The most important thing is to hold a VERY SHORT
arc. (A long arc will result in falling molten metal; a
short arc will make the metal stay.)
If necessary — and that is dictated by the looks of
the molten puddle — a slight back and forth motion
along the seam with the electrode will help prevent
“dripping.”
LEARNING TO STICK WELD
7
Each of these types of wear demands a different kind
of hardsurfacing electrode.
When applying the proper electrode, the service life of
the part will in most cases be more than double. For
instance, hardsurfacing of plowshares results in 3-5
times more acreage plowed.
How to Hardface the Sharp Edge (Metal to Ground
Wear)
1. Grind the share, approximately one inch (25mm)
wide along the edge, so the metal is bright.
2. Place the share on an incline of approximately 2030°. The easiest way to do this is to put one end of
the share on a brick. (See drawing.)
Most users will want to hardface the underside of
the share, but some might find that the wear is on
the top side. The important thing is to hardface the
side that wears.
3. Use 1/8" (3.2mm) Wearshield™ ABR electrode at
90-105 amps. Strike the arc about one inch (25mm)
from the sharp edge.
4. The bead should be put on with a weaving motion,
and it should be 1/2” to 3/4" (12.5 to 19mm) wide.
Do not let the arc blow over the edge, as that will
dull the edge. (See drawing.)
Welding Sheet Metal
Welding sheet metal presents an additional problem.
The thinness of the metal makes it very easy to burn
through. Follow these few simple rules:
1. Hold a very short arc. (This prevents burn through,
since beginners seem to hold too long an arc.)
2. Use 1/8” (3.2mm) or 3/32" (2.4mm) Fleetweld® 180
electrode.
3. Use low amperage. 75 amps for 1/8" (3.2mm) electrode, 40-60 amps for 3/32" (2.4mm) electrode.
4. Move fast. Don’t keep the heat on any given point
too long. Keep going. Whip the electrode.
5. Use lap welds whenever possible. This doubles the
thickness of the metal.
Hardfacing
There are several kinds of wear. The two most often
encountered are:
1. Metal to Ground Wear.
(Plowshares, bulldozer blades, buckets, cultivator
shares, and other metal parts moving in the soil.)
2. Metal to Metal Wear.
(Trunnions, shafts, rollers and idlers, crane and
mine car wheels, etc.)
5. Use the back-stepping method. Begin to weld 3"
(75mm) from the heel of the share and weld to the
heel. The second weld will begin 6" (150mm) from
the heel, the third weld 9" (225mm) from the heel,
etc.
BACK-STEPPING
Back-stepping greatly reduces the chances for cracking of the share, and it also greatly reduces possible
warpage.
NOTE: The entire process is rather fast. Many beginners go much too slow when hardfacing plow shares,
running the risk of burning through the thin metal.
8
Hardfacing of Idler and Roller (Metal to Metal Wear)
A very common application of hardfacing for metal to
metal wear is the hardfacing of idlers and rollers and
the rails that ride on these rollers and idlers.
The reason for hardfacing these parts is primarily
monetary. A few dollars worth of electrode will completely build up a roller or idler, and the hard surface
will outlast several times the normal life or such rollers
and idlers.
LEARNING TO STICK WELD
8
NOTE: The same electrode — Wearshield™ BU —
will give the operator two desired hardnesses, just by
a difference in cooling rate, making it possible to put
the hardest deposit on the most expensive parts.
NOTE: The outside of the rails (the side that comes in
contact with the ground) should be surfaced with
Wearshield™ ABR, since this side has Metal to
Ground wear.
Welding Cast Iron
If the following procedure is followed, it is not even
necessary to remove the grease bearing while welding. This will save a lot of time:
1. The roller (or idler) is inserted on a piece of pipe
that is resting on two sawbucks. This enables the
operator to turn it while welding.
2. Use Wearshield™ BU electrodes, 5/32" (4.0mm) at
175 amps or 3/16" (4.8mm) at 200 amps.
3. Weld across the wearing surface. Do not weld
around.
4. Keep the roller (or idler) cool by quenching with
water, and by stopping the welding periodically.
This will prevent shrinking of the roller (or idler) on
the grease bearing.
5. Build-up to dimension. The weld metal deposited by
Wearshield™ BU electrode is often so smooth that
machining or grinding is not necessary.
NOTE: The quenching of the roller (or idler) has
another purpose: It increases the hardness — and
thus the service life — of the deposit.
When welding on a piece of cold cast iron, the
tremendous heat from the arc will be absorbed and
distributed rapidly into the cold mass. This heating
and sudden cooling creates WHITE, BRITTLE cast
iron in the fusion zone.
This is the reason why welds in cast iron break.
Actually, one piece of the broken cast iron has the
entire weld on it, and the other piece has no weld on
it.
In order to overcome this, the welding operator has
two choices:
1. He can preheat the entire casting to 500-1200°F.
(260-649°C). If the cast iron is hot before welding,
there will be no sudden chilling which creates brittle
white cast iron. The entire casting will cool slowly.
The hardfacing of the rails is a lot easier:
1. Place the rails with the side that rides on the rollers
and idlers upwards.
2. Use Wearshield™ BU electrodes, 5/32" (4.0mm) at
175 amps or 3/16" (4.8mm) at 200 amps.
3. Build-up to size.
4. Do not quench. This will make the deposit slightly
softer than the deposit on the idlers and rollers.
That means that the wear will primarily be on the
rails, which are a lot easier and less time-consuming and cheaper to build-up.
2. He can weld 1/2" (12.5mm) at a time, and not weld
at that spot again until the weld is completely cool
to the touch.
In this way no large amount of heat is put into the
mass.
Most inexperienced welders will probably use the second method, because they have no way of preheating
large castings. Smaller castings can easily (and
should) be preheated before welding. A forge, stove, a
fire, or the Arc Torch are all excellent means of preheating.
When using the 1/2" (12.5mm) at a time method, it is
recommended to start 1/2" (12.5mm) away from the
previous bead and weld into the previous bead (backstepping).
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