Lincoln Electric LTW2 User Manual [en, es, fr]
Welding Guide
LEARNING TO STICK WELD
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Welding Safety
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LTW2 | Issue D ate 07/13
© Lincoln Global, Inc. All Rights Reserved.
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.
WARNING
This statement appears where the information must be followed
exactly to avoid serious personal injury or loss of life.
CAUTION
This statement appears where the information must be followed to
avoid minor personal injury or damage to this equipment.
DON’T get too close to the arc. Use
corrective lenses if necessary to
stay a reasonable distance away
from the arc.
READ and obey the Material Safety
Data Sheet (MSDS) and the warning
label that appears on all containers
of welding materials.
USE ENOUGH VENTILATION or
exhaust at the arc, or both, to keep
the fumes and gases from your breathing zone and the general area.
IN A LARGE ROOM OR OUTDOORS, natural ventilation may be
adequate if you keep your head out of the fumes (see below).
USE NATURAL DRAFTS or fans to keep the fumes away from your
face.
If you de velop unusual symptoms, see your supervisor. Perhaps the
welding atmosphere and ventilation system should be checked.
PROTECT your eyes and face with welding helmet
properly fitted and with proper grade of filter plate
(See ANSI Z49.1).
PROTECT your body from welding spatter and arc
flash with protective clothing including woolen
clothing, flame-proof apron and gloves, leather
leggings, and high boots.
PROTECT others from splatter, flash, and glare with
protective screens or barriers.
IN SOME AREAS, protection from noise may be
appropriate.
BE SURE protective equipment is in good condition.
ALSO, WEAR SAFETY GLASSES IN WORK
AREA AT ALL TIMES.
DO NOT WELD OR CUT containers or materials which have
previously been in contact with hazardous substances unless they are
properly cleaned. This is extremely dangerous.
DO NOT WELD OR CUT painted or plated parts unless special
precautions with ventilation have been taken. They can release highly
toxic fumes or gases.
Additional precautionary measures
PROTECT compressed gas cylinders from excessive heat, mechanical
shocks, and arcs; fasten cylinders so they cannot fall.
BE SURE cylinders are never grounded or part of an electrical circuit.
REMOVE all potential fire hazards from welding area.
ALWAYS HAVE FIRE FIGHTING EQUIPMENT READY FOR
IMMEDIATE USE AND KNOW HOW TO USE IT.
LEARNING TO STICK WELD
Learn to Stick Weld .......................................................................................................1
Arc Welding Circuit....................................................................................................1
What Happens in the Arc ..........................................................................................1
Correct Welding Position...........................................................................................2
Correct Way to Strike an Arc ....................................................................................2
Correct Arc Length ....................................................................................................2
TABLE OF CONTENTS
Page
Practice .....................................................................................................................3
Common Metals..................................................................................................3
Joint Types and Positions.................................................................................4
Butt Joint...........................................................................................................4
Penetration .......................................................................................................4
Fillet Joint..........................................................................................................4
Multi Pass Welds ................................................................................................5
Welding in the Vertical Position ..........................................................................5
Vertical-Up Welding ............................................................................................5
Vertical-Down Welding .......................................................................................5
Overhead Welding ..............................................................................................6
Welding Sheet Metal...........................................................................................6
Hardfacing ..........................................................................................................6
How to hardface the Sharp Edge........................................................................6
Hardfacing of Idler and Roller .............................................................................7
Welding Cast Iron ...............................................................................................7
Cast Iron Plate Preparation ................................................................................8
3
LEARNING TO STICK WELD
To electrical
(earth) ground.
LEARNING TO STICK WELD
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 operator’s knowledge of arc welding must go beyond the arc
itself. If you want to get the most out of your welding practice, your
knowledge of welding must go beyond the arc. You also need to
understand how to control the arc, and this requires 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.
This arc-welding circuit has a voltage output of up to 79 volts, which
is enough to 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. The holder
is held by the welder.
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.
FIGURE 2—The welding arc
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 both very bright and very hot. If you look at the
arc with your naked eye, you risk several hours’ or days’ worth of
pain and poor, blurry vision. A welding helmet with a very dark lens,
specifically designed for arc welding, must be used whenever viewing
the arc.
Have you ever watched water flow from a garden hose onto soft soil
or earth? Eventually, the water will build up enough to displace and
dig into the soil beneath it. It may even form a small crater that then
fills with water. The arc works the same way, melting the base metal
and actually digging into it as it moves across the surface of the base
metal. 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.
WARNING
ELECTRIC SHOCK CAN KILL.
CAREFULLY REVIEW THE ARC WELDING
SAFETY PRECAUTIONS AT THE BEGINNING
OF YOUR OPERATOR’S MANUAL.
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 .
FIGURE 1—The welding circuit for Shielded Metal
Arc Welding(SMAW)
ARC RAYS CAN BURN
EYES AND SKIN.
PROTECT YOURSELF AND OTHERS, READ
“ARC RAYS CAN BURN” AT THE FRONT OF THE
OPERATOR’S MANUAL SUPPLIED WITH THE
WELDER.
1
LEARNING TO STICK WELD
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 the following
aspects:
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
The following 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.
2. The Correct Way to Strike an Arc
Be sure the work clamp makes good electrical contact to
the work.
Lower your autodarkening or fixed shade welding helmet.
Scratch the electrode slowly over the metal and you will see
sparks flying. While scratching, lift the electrode 1/8"
(3.2mm) to establish the arc.
NOTE: If you stop moving the electrode while scratching,
the electrode will stick.
NOTE: Most beginners try to strike the arc by making a fast jabbing motion
down onto the plate. Result: They either stick or their motion is so fast
that they break the arc immediately.
3. The Correct Arc Length
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, it 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. The Correct Welding Speed
1. The Correct Welding Position
At first, you may find it easier to use the two-handed
technique shown below. This requires the use of a welding
helmet.
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 right-handed).
This enables you to see clearly what you are doing.
Hold the electrode at a slight angle as shown.
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.
The tendancy is to weld too fast, resulting in a thin, uneven,
“wormy” looking bead. 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.
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LEARNING TO STICK WELD
PRACTICE
Use the following exercise to spend a little more time 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
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.
Use both hands.
2. When you can strike an arc without sticking, practice
the correct arc length. Learn to distinguish it by its
sound.
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.
3
LEARNING TO STICK WELD
JOINT TYPES AND
POSITIONS
Five types of welding joints are: Butt joint, Fillet joint, Lap joint, Edge
joint and Corner joint. See Figure 3.
FIGURE 3
Of these, the Butt Joint and Fillet Joint are the two most common
welds.
Butt joint Lap joint
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.
Edge joint Fillet joint Corner joint
Butt Joints
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”.
4
LEARNING TO STICK WELD
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.
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 challenge, 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:
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.
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 vertical-down 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.
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.
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.)
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.’’)
5. The upward motion of the arc is caused by a very slight wrist
motion. 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 with a correct 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
5
LEARNING TO STICK WELD
BACK-STEPPING
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 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.”
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.
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 20-30°. 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.)
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 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 slowly
when hardfacing plow shares, running the risk of burning through the thin
metal.
Hardfacing
There are several kinds of wear. The two most often encountered are
as follows:
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.)
Each of these types of wear demands a different kind of
hardsurfacing electrode.
When the proper electrode is applied, hardsurfacing can more than
double the service life of the part. For instance, hardsurfacing of
plowshares results in 3-5 times more acreage plowed.
6
LEARNING TO STICK WELD
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.
If the below 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.
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 timeconsuming and cheaper to build up.
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
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. 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.
2. 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.
If you have no way of preheating large castings, you’ll probably find it
easier to use the second of the two methods discussed above.
However, smaller castings can easily be preheated before welding by
using a forge, stove, fire, or Arc Torch.
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).
After welding Cast Iron, protect the casting against fast cooling. Put it
in a sand (or lime) box.
If sand or lime is not available, cover it with sheet metal or any other
non-flammable material that will exclude drafts and retain heat.
Cast Iron Plate Preparation
Wherever practical, the joint to be welded should be “veed” out by
grinding or filing to give complete penetration. This is especially
important on thick castings where maximum strength is required. In
some instances, a back-up strip may be used and plates may be
gapped 1/8" (3.2mm) or more.
On sections where only a sealed joint is required and strength is not
important, the joint may be welded after slightly veeing out the seam
as shown.
7
LEARNING TO STICK WELD
8
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