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Basic Welding Terms
Scroll down or Jump straight to a heading below Welding
Consumables Welding Equipment Cutting Welding Automation / Robotic
Welding
What is Arc Welding? Arc welding is a method of joining two
pieces of metal into one solid piece. To do this, the heat of an
electric arc is concentrated on the edges of two pieces of metal to
be joined. The metal melts, while the edges are still molten,
additional melted metal is added. This molten mass then cools and
solidifies into one solid piece. Find out more by reading one of
the articles below:q q q
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Safe Practices Promote Arc Welding Safety Arc Welding
Fundamentals Power Shopping: Choosing the Ideal Welding Power
Source by Selecting the Proper Welding Process 20 Frequently Asked
Questions AWS Classifications Explained
Welding Consumables
Stick Electrode A short stick of welding filler metal consisting
of a core of bare electrode covered by chemical or metallic
materials that provide shielding of the welding arc against the
surrounding air. It also completes the electrical circuit, thereby
creating the arc. (Also known as SMAW, or Stick Metal Arc
Welding.)
Learn More:q
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Creating High Quality Stick Welds: A Users Guide How To Strike
and Establish an Arc 20 Frequently Asked Questions
MIG Wire Like a stick electrode, MIG wire completes the
electrical circuit creating the arc, but it is continually fed
through a welding gun from a spool or drum. MIG wire is a solid,
non-coated wire and receives shielding from a mixture of gases.
(Process is also known as GMAW, or Gas Metal Arc Welding.) Learn
More:q q q q
Common Problems and Remedies for GMAW 20 Frequently Asked
Questions Frequently Asked MIG welding Questions MIG vs.
Flux-Cored: Which Welding Process is Right for You?
Cored Wire (Flux-Cored Wire) Cored wire is similar to MIG wire
in that it is spooled filler metal for continuous welding. However,
Cored wire is not solid, but contains flux internally (chemical
& metallic materials) that provides shielding. Gas is often not
required for shielding. (Process is also known as FCAW, or
Flux-Cored Arc Welding.) Learn More:q q
20 Frequently Asked Questions MIG vs. Flux-Cored: Which Welding
Process is Right for You?
Submerged Arc A bare metal wire is used in conjunction with a
separate flux. Flux is a granular composition of chemical and
metallic materials that shields the arc. The actual point of metal
fusion, and the arc, is submerged within the flux. (Process is also
known as SAW, or Submerged Arc Welding.)
Stainless Steel Stainless steel electrodes and wire are used for
welding applications where corrosion resistance is required.
Stainless steel consumables are designed to match the composition
of stainless steel base metals. Learn More:q
MIG welding Stainless Steel
Hardfacing A stick of electrode or cored wire that is designed
not to fuse two pieces of metal together, but to add a layer of
surface metal to a work-piece in order to reduce wear. An example
of this is the shovel on an excavator.
Welding Equipment
Stick Welders Heating the coated stick electrode and the base
metal with an arc creates fusion of metals. An AC and/or DC
electrical current is produced by this machine to create the heat
needed. An electrode holder handles stick electrodes and a ground
clamp completes the circuit. Learn More:q q q q
Creating High Quality Stick Welds: A Users How To Strike and
Establish an Arc 20 Frequently Asked Questions Summer Projects:
Weld Your Own Texas Grill!
TIG Welders A less intense current produces a finer, more
aesthetically pleasing weld appearance. A tungsten electrode
(non-consumable) is used to carry the arc to the workpiece. Filler
metals are sometimes supplied with a separate electrode. Gas is
used for shielding. (Process is also known as GTAW, or Gas Tungsten
Arc Welding.)
MIG Welders and Multi-Process Welders Constant Voltage and
Constant Current welders are used for MIG welding and are a
semi-automated process when used in conjunction with a wire feeder.
Wire is fed through a gun to the weld-joint as long as the trigger
is depressed. This process is easier to operate than stick welding
and provides higher productivity levels. CC/CV welders operate
similarily to CC (MIG) welders except that they possess
multiprocess capabilities - meaning that they are capable of
performing flux-cored, stick and even TIG processes as well as MIG.
Learn More:q q q
Common Problems and Remedies for GMAW 20 Frequently Asked
Questions Frequently Asked MIG welding Questions
Engine Driven Welders Large stick or multi-process welders are
able to operate independent of input power and are powered by a
gasoline, diesel, or LPG engine instead. Ideal for construction
sites and places where power is unavailable. Learn More:q
How To Select the Right Engine Driven Welder for the Job
Wire Feeder / Welders For MIG welding or Flux-Cored wire
welding, wire feeder welders are usually
complete and portable welding kits. A small built in wire feeder
guides wire through the gun to the piece. Learn More:q q q q q
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How To Select a Compact Wire Feeder Welder Using tools
Wire-Feeder Welders Common Problems and Remedies for GMAW 20
Frequently Asked Questions Frequently Asked MIG welding Questions
MIG Welding Aluminum with Lincoln Compact Wire Feeder Welders
Semiautomatic Wire Feeders For MIG welding or Flux-Cored
welding, semiautomatic wire feeders are connected to a welding
power source and are used to feed a spool of wire through the
welding gun. Wire is only fed when the trigger is depressed. These
units are portable.
Automatic Wire Feeders For MIG, Flux-Cored, or submerged arc
welding, automatic wire feeders feed a spool of wire at a constant
rate to the weld joint. They are usually mounted onto a fixture in
a factory/industrial setting and are used in conjunction with a
separate power source.
Magnum Guns / Torches MIG welding guns and TIG welding torches
are handheld welding application tools connected to both the wire
feeder and power source. They direct the welding wire to the weld
joint and control the wire feed with the use of a trigger
mechanism.
Cutting
Plasma Cutters A constricted cutting arc is created by this
machine, which easily slices through metals. A high velocity jet of
ionized gas removes molten material from the application. Learn
More:q
Plasma cutting: Determining if its Right for You and What to
Look for in a Machine
Oxyfuel Gas Cutting Oxyfuel gas cutting process involves
preheating the base metal to a bright cherry red, then introducing
a stream of cutting oxygen which will ignite and burn the metal.
Learn more on Oxyfuel Gas Cutting
Welding Automation / Robotic Welding Robotic Welding Systems The
combination of a robotic arm, a welding power source and a wire
feeder produces welds automatically using various programs, welding
fixtures and accessories. Learn More on Robotic Welding and Welding
Automation.
Environmental Systems Also known as fume extraction, these
systems are often incorporated into a robotic fixture to remove
welding fumes natural to the process from the welding environment.
Usually a vacuum unit, they can be portable or mounted onto a wall.
View Fume Extraction Packages
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by Ken Brown, Project Research Manager, The Lincoln Electric
Company
Safe Practices Promote Arc Welding Safety
Arc welding is a safe process when sufficient measures are taken
to protect the welder from potential hazards and when proper
operating practices are followed. Major hazards welders can
encounter if these dangers are overlooked include fumes and gases,
arc rays and sparks, and electric shock. Here are a few of the main
precautions that will help welders avoid trouble. For further
safety information and details on safe welding, contact the
manufacturer of your welding equipment or the American Welding
Society. Everyone with welding responsibility should also be
familiar with ANSI standard Z49.1, "Safety in Welding and Cutting."
Fumes and Gases Are Silent Hazards The fumes and gases that result
from the welding process can cause acute or chronic health effects
if proper precautions are ignored. The fume plume contains solid
particles from the consumables (electrodes), base metal, base metal
coating and gases formed in the process, which include oxides of
nitrogen and ozone.. The gases used for shielding (argon, helium,
and carbon dioxide) are nontoxic, but as they are released, they
displace oxygen in breathing air. This can cause dizziness,
unconsciousness, and even death with longer exposures. Avoid
exposure to fumes and gases whenever possible, and use ventilation
equipment or a respirator when necessary.
Here are some suggestions:q q
Keep your head out of the fumes. Use enough ventilation or
exhaust to remove fumes and gases from the work area. Mechanical
equipment should exhaust at least 2000 cfm of air for each welder,
except where individual exhaust hoods, booths, or air-line
respirators
are used.q
Natural ventilation may be used under certain conditions. For
welding or cutting mild steel, natural ventilation is usually
sufficient if a room has at least 10,000 cubic feet per welder,
with a ceiling height of at least 16 feet. Cross-ventilation should
not be blocked, and welding should not be done in a confined
space.
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Don't get too close to the arc ("Avoid the plume"). Use
corrective lenses to help you maintain the proper distance if
necessary. Read and understand the Material Safety Data Sheets
(MSDS) for the product. Read and obey warning labels on all
containers of welding materials. Use a smoke extractor-type welding
gun for semiautomatic welding processes. Arc Rays and Sparks Can
Injure Eyes and Burn Skin These are the most obvious hazards
because they are the most visible. However, they should not be
taken for granted. While the dangers may be well recognized,
consider these factors:q Protect your eyes and face with a properly
fitted welding helmet that is equipped with the correct grade of
filter plate (See ANSI Z49.1 and Z87.1 standards). Fig. 1 shows
suggested shade numbers for various arc welding processes. Infrared
radiation can cause retinal burning and cataracts. Even brief
exposure to ultraviolet (UV) radiation can cause an eye burn known
as "welder's flash," which results in extreme discomfort, swelling,
fluid excretion, and possibly temporary blindness.
q
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Protect your body from welding spatter and arc flash with
clothing made from durable, flame-resistant material, such as
woolen fabrics, and gear that includes flame-proof apron and
gloves, leather leggings, and high boots. Avoid clothing made of
synthetic materials, which can melt when exposed to extreme heat or
sparks, or cotton unless it is specially treated for fire
protection. Keep your clothes free of grease and oil, which may
ignite. Protect others from spatter, flash, and glare with
non-flammable protective screens or curtains. Be sure to wear
safety glasses with side shields when in a welding area.
Electric Shock Can Kill
The hazards of electric shock are one of the most serious risks
facing a welder. Contact with equipment or metal parts that are
electrically "hot' can cause injury or death from the shock or from
a fall that results from reaction to the shock. Primary voltage
shock (i.e., 230, 460 volts) is the most serious danger because it
is much greater than secondary voltage shock (i.e, 60 - 100 volts).
Primary voltage shock comes from touching a lead inside the welding
power source while you have your body or hand in contact with the
welder case or other grounded metal. Turning the equipment's power
switch "off" does not turn power off inside the case. Never remove
panels without unplugging the input power cord or turning the power
disconnect switch off. Secondary voltage shock comes from touching
part of the welding circuit, such as a bare spot on the electrode
cable, while also touching the grounded metal workpiece. Avoid
touching both parts of a circuit at the same time.q
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Be sure you are insulated from the workpiece and ground, as well
as other live electrical parts. Don't lean on the workpiece. Use
plywood, rubber mats or other dry insulation to stand on, and wear
dry, hole-free gloves. Stay dry, and do not weld when you are wet.
Never dip the electrode in water to cool it. Check equipment to be
sure it is properly grounded, in good repair, and installed
according to prevailing codes. Be sure equipment is turned off when
not in use. Electric current flowing through a conductor causes
Electric and Magnetic Fields (EMF), which can interfere with
pacemakers and may effect health in other ways. Consult your
physician before arc welding if you have a pacemaker. To avoid
excessive exposure to EMF, keep the electrode and work cables
together, never place your body between the two cables or coil the
electrode lead around your body, and do not work directly next to
the welding power source. Other Hazards to Watch Welding sparks can
cause fire or explosion and can easily go through small cracks and
openings or spray up to 35 feet to adjacent areas. Remove fire
hazards from the welding area or cover them with a fire-resistant
shield if necessary. Do not weld near unshielded fuel or hydraulic
lines.
Cylinders used for shielding gas in some processes can explode
if handled improperly. Always store and handle them safely, keep
them upright, and protect them from mechanical shocks or falling.
Maintain all hoses, fittings and regulators in good condition.
Never allow the electrode or any electrically "hot" parts of the
welding equipment to touch a cylinder.
Do not weld near fumes from other processes, such as cleaning,
degreasing or painting. Some fumes may cause an explosion, and
others can form highly toxic gases when exposed to welding arcs and
heat. Ear plugs or muffs will help prevent hearing loss from
working around noisy arc welding equipment or some processes. They
also will keep flying sparks out of your ears, especially when
welding overhead or in close quarters. Hearing loss can be gradual
and will add up over time, so ear protection is always a good
idea.
Welding is indispensable to numerous industrial and consumer
products, as it plays a key role in building and maintaining the
equipment, tools and infrastructure that make our abundant
lifestyle possible. Done properly, it is safe, productive and
efficient. Poor safety techniques often translate into poor quality
as well as posing a hazard to operators and other people in the
area. Insistence on strict safety requirements for welding
operations will pay off in employee health and productivity.
Supplement 1 Guide for Shade Numbers Electrode Size 1/32 in. (mm)
Less than 3 (2.5) 3-5 (2.5-4) 5-8 (4.-6.4) More than 8 (6.4) .. Arc
Current (A) Less than 60 60-160 160-250 250-550 Less than 60 60-160
260-250 250-500 Less than 50 50-150 150-500 (Light) (Heavy) Less
than 500 500-1000 Minimum Suggested(1) Protective Shade No. Shade
(Comfort) 7 8 10 11 7 10 10 10 8 8 10 10 11 10 12 14 11 12 14 10 12
14 12 14
Operation Shielded metal arc welding
Gas metal arc welding and flux cored arc welding
Gas tungsten arc welding
..
Air carbon arc cutting
Plasma arc welding .. Plasma arc cutting (Light)2 (Medium)2
(Heavy)2 .. .. ..
Less than 20 20-100 100-400 400-800 Less than 300 300-400
400-800 mm Under 3.2 3.2 to 12.7 Over 12.7 Under 25 25 to 150 Over
150
6 8 10 11 8 9 10 ..
6 to 8 10 12 14 9 12 14 3 or 4 2 14 .. 4 or 5 5 or 6 6 or 8 3 or
4 4 or 5 5 or 6
Torch brazing Torch soldering Carbon arc welding .. Gas welding
Light Medium Heavy Oxygen cutting Light Medium Heavy in.
Plate thickness
Under 1/8 1/8 to 1/2 Over 1/2 Under 1 1 to 6 Over 6
..
..
(1) As a rule of thumb, start with a shade that is too dark to
see the weld zone. Then go to a lighter shade which gives
sufficient view of the weld zone without going below the minimum.
In oxyfeul gas welding or cutting where the torch produces a high
yellow light, it is desirable to use a filter lens that absorbs the
yellow or sodium line in the visible light of the (spectrum)
operation. (2) These values apply where the actual arc is clearly
seen. Experience has shown that lighter filters may be used when
the arc is hidden by the workpiece. Data from ANSI/ASC Z49.1-88
Welding Safety
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The Lincoln Electric Company, 1994.
Arc-Welding Fundamentals
Arc welding is one of several fusion processes for joining
metals. By applying intense heat, metal at the joint between two
parts is melted and caused to intermix - directly, or more
commonly, with an intermediate molten filler metal. Upon cooling
and solidification, a metallurgical bond is created. Since the
joining is an intermixture of metals, the final weldment
potentially has the same strength properties as the metal of the
parts. This is in sharp contrast to non-fusion processes of joining
(i.e. soldering, brazing etc.) in which the mechanical and physical
properties of the base materials cannot be duplicated at the joint.
In arc welding, the intense heat needed to melt metal is produced
by an electric arc. The arc is formed between the actual work and
an electrode (stick or wire) that is manually or mechanically
guided along the joint. The electrode can either be a rod with the
purpose of simply carrying the current between the tip and the
work. Or, it may be a specially prepared rod or wire that not only
conducts the current but also melts and supplies filler metal to
the joint. Most welding in the manufacture of steel products uses
the second type of electrode. Basic Welding Circuit Fig. 1 The
basic arc-welding circuit
The basic arc-welding circuit is illustrated in Fig. 1. An AC or
DC power source, fitted with whatever controls may be needed, is
connected by a work cable to the workpiece and by a "hot" cable to
an electrode holder of some type, which makes an electrical contact
with the welding electrode. An arc is created across the gap when
the energized circuit and the electrode tip touches the workpiece
and is withdrawn, yet still with in close contact. The arc produces
a temperature of about 6500F at the tip. This heat melts both the
base metal and the electrode, producing a pool of molten metal
sometimes called a "crater." The crater solidifies behind the
electrode as it is moved along the joint. The result is a fusion
bond.
Arc Shielding However, joining metals requires more than moving
an electrode along a joint. Metals at high temperatures tend to
react chemically with elements in the air - oxygen and nitrogen.
When metal in the molten pool comes into contact with air, oxides
and nitrides form which destroy the strength and toughness of the
weld joint. Therefore, many arc-welding processes provide some
means of covering the arc and the molten pool with a protective
shield of gas, vapor, or slag. This is called arc shielding. This
shielding prevents or minimizes contact of the molten metal with
air. Shielding also may improve the weld. An example is a granular
flux, which actually adds deoxidizers to the weld. Figure 2
illustrates the shielding of the welding arc and molten pool with a
Stick electrode. The extruded covering on the filler metal rod,
provides a shielding gas at the point of contact while the slag
protects the fresh weld from the air. The arc itself is a very
complex phenomenon. Indepth understanding of the physics of the arc
is of little value to the welder, but some knowledge of its general
characteristics can be useful. Nature of the Arc An arc is an
electric current flowing between two electrodes through an ionized
column of gas. A negatively charged cathode and a positively
charged anode create the intense heat of the welding arc. Negative
and positive ions are bounced off of each other in the plasma
column at an accelerated rate. Fig. 2 This shows how the coating on
a coated (stick) electrode provides a gaseous shield around the arc
and a slag covering on the hot weld deposit.
In welding, the arc not only provides the heat needed to melt
the electrode and the base metal, but under certain conditions must
also supply the means to transport the molten metal from the tip of
the electrode to the work. Several mechanisms for metal transfer
exist. Two (of many) examples include: 1. Surface Tension Transfer
- a drop of molten metal touches the molten metal pool and is drawn
into it by surface tension. 2. Spray Arc - the drop is ejected from
the molten metal at the electrode tip by an electric pinch
propelling it to the molten pool. (great for overhead welding!) If
an electrode is consumable, the tip melts under the heat of the arc
and molten droplets are detached and transported to the work
through the arc column. Any arc welding system in which the
electrode is melted off to become part of the weld is described as
metal-arc. In carbon or tungsten (TIG) welding there are no molten
droplets to be forced across the gap and onto the work. Filler
metal is melted into the joint from a separate rod or wire. More of
the heat developed by the arc is transferred to the weld pool with
consumable
electrodes. This produces higher thermal efficiencies and
narrower heat-affected zones. Since there must be an ionized path
to conduct electricity across a gap, the mere switching on of the
welding current with an electrically cold electrode posed over it
will not start the arc. The arc must be ignited. This is caused by
either supplying an initial voltage high enough to cause a
discharge or by touching the electrode to the work and then
withdrawing it as the contact area becomes heated. Arc welding may
be done with direct current (DC) with the electrode either positive
or negative or alternating current (AC). The choice of current and
polarity depends on the process, the type of electrode, the arc
atmosphere, and the metal being welded.
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Power Shopping: Choosing the Ideal Welding Power Source by
Selecting the Proper Welding Process
The process of choosing a welding power source is much like that
of buying a car. It involves searching for a product that is
efficient, powerful, easy to handle and, most importantly, suited
to the customer's particular needs. But with such a wide selection
of power sources on the market, how do welders select the right one
for them? The first step is to understand their shop's internal
needs. To determine this, examine some commonly used welding
processes and for which materials they are best suited. Gas Metal
Arc Welding (GMAW)/Flux-Cored Arc Welding (FCAW) GMAW/FCAW (most
commonly referred to as MIG or Flux-Cored Welding) uses a spool of
wire that is either housed inside the power source or fed from an
external wire feeder. This wire or filler material is fed through a
welding gun. The power source is used to start and maintain the arc
between the wire and the base metal. GMAW or MIG welding utilizes
solid metal wire, which requires the use of a shielding gas to
protect the weld puddle from the atmosphere. FCAW uses a hollow
wire filled with a flux powder that may or may not need an external
shielding gas, because the gas may be produced from the flux within
the wire as it burns in the arc. The flux in the wire serves many
of the same purposes as the electrode coating in SMAW.
GMAW requires the least operator skill, because the machine
feeds the wire. The welding operator holds the gun in one hand,
squeezes the trigger, and welds. It's that easy! The shielding gas
makes for a very smooth arc that remains stable. Since other
processes
typically require very specific electrode positioning and
manipulation, GMAW is the fastest growing process. With compact
units now retailing for less than $500 and the ability to easily
weld on much thinner material than stick electrode, this type of
unit has become very popular. Welding speeds are also higher
because of the continuously fed electrode, absence of slag (with
GMAW) and higher filler metal deposition rates. Its operating
factor is typically 30-50 percent so 3-5 minutes out of every 10
can be spent creating an arc. In addition, GMAW/ FCAW does not
require the degree of operator skill that TIG or stick welding
does. GMAW can be used on all of the major commercial metals. FCAW
is currently used primarily on steels and stainless steels. These
two processes also can be used over a wide range of material
thickness and operate in all positions. For these reasons, they are
usually the welding processes of choice for most fabrication and
production shops. On the downside, equipment for GMAW and FCAW is
more complex, more costly and traditionally less portable than
stick welding processes (although some new portable models do
exist). Welding is typically done within a 10 to 12 foot radius of
the wire feeder and the work is usually brought to the weld
station. Shielded Metal Arc Welding (SMAW) SMAW, or stick welding,
is the most common form of arc welding. In the process, a stick or
electrode is placed at the end of a holder. Using electricity from
the power source, an arc is struck between the tip of the electrode
and the metal welding surface. The heat of the arc melts the tip of
the electrode creating the filler material that is deposited as the
electrode is consumed. A coated material on the electrode burns and
protects the arc from the atmosphere. The burning of the coating
produces CO2, which becomes the shielding gas. A slag is also
formed which helps refine the weld metal and protect it as it
freezes. SMAW is one of the easiest and most versatile ways to
weld, since filler material can be easily changed to match
different metals just by switching stick electrodes. Whether it is
steel, stainless steel, cast iron or high alloy metals, users can
clamp in a new rod to be ready for the next project. In addition,
stick is versatile because it takes the least equipment, which
makes it easy to setup or move to a new location.
When compared to other types of power sources, SMAW welders are
generally the least expensive. As a result, they are utilized most
often by novice welders, farmers, smaller fabricating shops,
maintenance shops and large field construction contractors that
weld on a variety of jobs over a large physical area.
The main disadvantage to SMAW is the amount of downtime
associated with the process. An electrode is only so many inches in
length and must be changed once it is consumed. This requires the
operator to stop welding to change the electrode. Frequently, the
amount of skill required by the operator is greater than that
required for wire fed processes. In addition, it takes time to chip
or grind the slag or impurities from the weld. The operating factor
or time that the welder is actually "creating sparks" is typically
two to three minutes per 10-minute interval. In general, stick
welders sacrifice productivity for versatility. Gas Tungsten Arc
Welding (GTAW) In GTAW, an electric arc is established between a
non-consumable tungsten electrode and the base metal. The arc zone
is filled with an inert gas, typically argon, which protects the
tungsten and molten metal from oxidation and provides an easily
ionized path for the arc current. GTAW produces high quality welds
on almost all metals and alloys. Because it can be controlled at
very low amperages, it is ideally suited for welding on thin metal
sheets and foils. The biggest advantage of GTAW is that high
quality welds can be made on almost any weldable metal or alloy.
Another major advantage is that filler metal can be added to the
weld pool independently of the arc current. With other arc welding
processes, the rate of filler metal addition controls the arc
current. Other advantages include low spatter, no slag and
relatively easy clean up.
The main disadvantage of GTAW is that it produces the slowest
metal deposition rate of all the processes. The emphasis is on
making welds that are perfect in appearance, which means lower
welding current and more welding time. The operator needs to learn
to coordinate precise movements of the torch in one hand with
adding filler metal from the other hand and controlling current
with a foot pedal. The operator also needs to learn how to properly
setup the GTAW machine. Tungsten preparation, spark intensity,
upslope, downslope, pulsing rate, peak intensity, background
current, high frequency and proper grounding can all be very
important issues for a GTAW welder. Combined with lower deposit
rates, it's easy to see how the GTAW process has a great following
in industries such as aerospace, where quality is much more
important than cost. Submerged Arc Welding (SAW) SAW uses a
continuously fed wire with a granular material called flux to cover
the weld area.
This type of welding is used primarily on heavier plate
applications such as structural steel and on specialized high speed
welding of light sections. The flux plays a central role in
achieving high speed and a quality weld. Very little welding fume
is produced, leaving the shop air much cleaner. Since the flux
covers the whole arc, a welding helmet is not required, leading to
a higher operating factor. On long, large welds, multipass and
overlay applications, the process can approach a 100 percent
operating factor. Productivity can be very high with welding
currents over 1000 amps common on automatic applications.
Disadvantages include limited welding positions, because flux
comes in granular form. Operators must weld on flat surfaces to
assure the flux covers the weld puddle. Another disadvantage is
that hot flux can burn shoes and cause handling problems that must
be addressed. With some knowledge of the types of welding processes
that are available, you should now be able to make a decision as to
which process best suits your needs. The next step is to start
looking for a power source. Your ideal power source should
accommodate your welding process, meet your size requirements, fit
within your budget and offer the technology features that are
needed in your shop. In the end, a reliable power source-like a
reliable carwill continue to serve you for many years to come.
Lincoln Electric Products
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20 Frequently Asked Questions
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The E7018 welding rods I've been buying are now marked E7018
H4R. What does the H4R mean? Are these rods different than the
E7018 rods I've used before? Why is hydrogen a concern in welding?
What is the maximum plate thickness which can be welded with
Innershield NR211MP (E71T-11) wire? What electrode can I use to
join mild steel to stainless steel? What consumable should be used
to weld cast iron? What consumable can be used to weld on SAE 4130
steel tubing? What consumable should be used for weathering steel?
What are you recommendations for welding AR400 plate? What
consumables are better for welding over rusty, dirty steel? What
flux-cored wires are better for welding on high sulfur steel? What
precautions should I take when welding T-1 steels? Why are the
Charpy impact values from my test welds lower than that printed on
your Certificate of Conformance? I'm using Outershield 71M (E71T-1)
flux-cored wire with 75Ar/25CO2. Why am I getting gas marks on the
weld surface? I'm welding with an Innershield FCAW-SS wire and
occasionally get porosity. How can I eliminate this? Can I use
flux-cored wires (FCAW-GS or FCAW-SS) on a constant current (CC)
stick welding power source? Why is preheat sometimes required
before welding? How should preheat be measured? What is interpass
temperature? Do I need an oven to store low hydrogen
electrodes?
q
q
q q q q
1. The E7018 welding rods I've been buying are now marked E7018
H4R. What does the H4R mean? Are these rods different than the
E7018 rods I've used before? H4R is an optional supplementary
designator, as defined in AWS A5.1-91 (Specification for shielded
metal arc welding electrodes). Basically, the number after the "H"
tells you the hydrogen level and the "R" means it's moisture
resistant. "H4" identifies electrodes meeting the requirements of
4ml average diffusible hydrogen content in 100g of deposited weld
metal when tested in the "asreceived" condition. "R" identifies
electrodes passing the absorbed moisture test after exposure to an
environment of 80F(26.7C) and 80% relative humidity for a period of
not less than 9 hours. The H4R suffix is basically just additional
information printed on the rod, and does not necessarily mean a
change in an electrode previously marked E7018. Back to Top 2. Why
is hydrogen a concern in welding? Hydrogen contributes to delayed
weld and/or heat affected zone cracking. Hydrogen combined with
high residual stresses and crack-sensitive steel may result in
cracking hours or days after the welding has been completed. High
strength steels, thick sections, and heavily restrained parts are
more susceptible to hydrogen cracking. On these materials, we
recommend using a low hydrogen process and consumable, and
following proper preheat, interpass, and postheat procedures. Also,
it is important to keep the weld joint free of oil, rust, paint,
and moisture as they are sources of hydrogen. Back to Top 3. What
is the maximum plate thickness which can be welded with Innershield
NR-211-MP (E71T-11) wire? NR-211-MP is restricted to welding these
maximum plate thicknesses: Wire diameter .035"(0.9mm) .045"(1.1mm)
.068"(1.7mm) 5/64"(2.0mm) 3/32"(2.4mm) Maximum plate thickness
5/16"(8mm) 5/16"(8mm) 1/2"(13mm) 1/2"(13mm) 1/2"(13mm)
For thicker steels, look to NR-212. It has similar welding
characteristics to NR211-MP but is designed for use on materials up
to 3/4" (19.0mm) thick. Back to Top 4. What electrode can I use to
join mild steel to stainless steel? Electrode selection is
determined from the base metal chemistries and the percent weld
admixture. The electrode should produce a weld deposit with a small
amount of ferrite (3-5 FN) needed to prevent cracking. When the
chemistries are not known, our Blue Max 2100 electrode, which
produces a high ferrite number, is commonly used. Back to Top 5.
What consumable should be used to weld cast iron? Cast irons are
alloys which typically have over 2% carbon plus 1-3% silicon and
are difficult to weld. Electrodes with a high percentage of nickel
are commonly used to repair cast iron. Nickel is very ductile,
making it a good choice to weld on cast iron, which is very
brittle. Softweld 99Ni and Softweld 55Ni are the Lincoln Electric
electrodes designed for welding cast iron. Back to Top 6. What
consumable can be used to weld on SAE 4130 steel tubing? On light
chrome-moly tubing, mild steel electrodes are commonly used. There
is enough pickup of alloy from the base material to give the
required tensile strength in the as-welded condition. On multiple
pass welds, Cro-Mo alloy electrodes are usually specified. Back to
Top 7. What consumable should be used for weathering steel? Core
Ten (A242 & A588) steels are weathering steels commonly used
for outdoor structures. These steels have a higher resistance to
atmospheric corrosion than typical mild steels. Often, welds on
these steels are specified for similar corrosion resistance and
color match. On single pass welds, mild steel electrodes are
commonly used. There is usually enough pickup from the base metal
to obtain a good color match. On multiple pass welds, low-alloy
electrodes are commonly used to obtain a good color match and
similar corrosion resistance. The electrodes commonly specified
include those with the suffixes -B1, -B2, -C1, -C2, and -C3.
Back to Top 8. What are you recommendations for welding AR400
plate? AR400 is a quench and tempered steel and may be difficult to
weld due its high strength and hardenability. The base steel around
the weld rapidly heats and cools during welding, resulting in a
heat affected zone (HAZ) with high hardness. Any hydrogen in the
weld metal may diffuse into HAZ and may cause hydrogen
embrittlement, resulting in delayed underbead or toe cracks outside
of the weld. To minimize heat affected zone cracking: 1. Use a low
hydrogen consumable with an -H4 or -H2 designation. 2. Preheat to
slow the cooling rate. Note that excessive preheat may anneal the
base material. 3. Slow cool. More time at elevated temperatures
allows the dissolved hydrogen to escape. 4. Peen the weld beads to
minimize residual weld stresses. 5. Use the lowest strength filler
metal meeting design requirements. If making fillet welds, the weld
can be oversized to give the specified strength 6. Minimize weld
restraint. Back to Top 9. What consumables are better for welding
over rusty, dirty steel? Steel should be cleaned of any oil,
grease, paint, and rust before using any arc welding process.
However, if complete cleaning cannot be performed, consumables that
form a slag, have deeper penetration, are slower freezing, or have
higher Silicon and Manganese are recommended for dirty steels.
These consumables include: SMAW: Fleetweld 5P+ GMAW: SuperArc L-56,
MC-710 FCAW-GS: Outershield 75 FCAW-SS: Innershield NR-311 SAW:
Lincolnweld 761 and 780 fluxes Back to Top 10. What flux-cored
wires are better for welding on high sulfur steel? AWS D5.20-95
FCAW Specification states that E70T-4 and E70T-7 flux-cored wires
are designed with a slag system to produce welds very low in sulfur
and resistant to hot cracking. Corresponding Lincoln products are
Innershield NS3M and NR-311 self-shielded flux-cored wires. Also
our E70T-5, Outershield 75-H gas-shielded flux-cored wire is also a
better choice for welding on high sulfur steels.
Back to Top 11. What precautions should I take when welding T-1
steels? T-1 is a quenched and tempered steel. Welding quenched
& tempered steels may be difficult due its high strength and
hardenability. The base steel around the weld is rapidly being
heated and cooled during welding, resulting in a heat affected zone
(HAZ) with high hardness. Hydrogen in the weld metal may diffuse
into HAZ and cause hydrogen embrittlement, resulting in delayed
underbead or toe cracking outside of the weld. To minimize heat
affected zone cracking: 1. Use a low hydrogen consumable, like a
-H4 or -H2. 2. Preheat. This slows the cooling rate. Note that
excessive preheat may anneal the base material. 3. Slow cool. More
time at elevated temperatures allows the dissolved hydrogen to
escape. 4. Peen the weld beads to minimize residual weld stresses.
5. Use the lowest strength filler metal meeting design
requirements. If making fillet welds, the weld can be oversized to
give the specified strength 6. Minimize weld restraint. Back to Top
12. Why are the Charpy impact values from my test welds lower than
that printed on your Certificate of Conformance? The test results
on our Certificate of Conformance were obtained from welding an AWS
filler metal test plate. Any change in welding procedure will
affect Charpy impact values. Below are common practices for welding
test plates when Charpy impact specimens are required: 1. 2. 3. 4.
Controlled heat input Controlled preheat and interpass temperature
Even number of passes per layer Build-up cap pass to maximum
allowed in specification
Back to Top 13. I'm using Outershield 71M (E71T-1) flux-cored
wire with 75Ar/25CO2. Why am I getting gas marks on the weld
surface? The fast freezing rutile slag on an E71T-1 Outershield
wire gives it excellent out-of-position characteristics, but can
also trap gases under the slag as the weld solidifies, resulting in
gas marks. Gas marks are more commonly observed welding at high
procedures under a high Argon blend shielding gas. Gas marking
and/or can be minimized by:
1. Switching to 100% CO2 shielding gas 2. 3. 4. 5. 6. Lowering
the welding procedure Cleaning the weld joint of paint, rust, and
moisture Minimize any wind disturbance Cleaning spatter from inside
gas nozzle Increasing the shielding gas flow rate
Back to Top 15. I'm welding with an Innershield FCAW-SS wire and
occasionally get porosity. How can I eliminate this? First, make
sure the steel is clean. Vaporization of contaminants on the base
metal such as moisture, rust, oil, and paint may cause porosity.
Second, this can be commonly caused by excessive voltage or too
short a stickout (the length of wire from the end of the contact
tip to the workpiece). Make sure these are within our recommended
parameters. Also, reducing the travel speed also helps minimize
porosity. Back to Top 16. Can I use flux-cored wires (FCAW-GS or
FCAW-SS) on a constant current (CC) stick welding power source? Our
flux-cored wires are designed to operate on constant voltage (CV)
DC machines. If used on a constant current (CC) machine, any small
changes in electrical stickout (length of the wire from the end of
the contact tip to workpiece) will produce large voltage
fluctuations, resulting in stubbing and porosity. Therefore, using
flux-cored wires on CC is not recommended. Back to Top 17. Why is
preheat sometimes required before welding? Preheating the steel to
be welded slows the cooling rate in the weld area. This may be
necessary to avoid cracking of the weld metal or heat affected
zone. The need for preheat increases with steel thickness, weld
restraint, the carbon/ alloy content of the steel, and the
diffusible hydrogen of the weld metal. Preheat is commonly applied
with fuel gas torches or electrical resistance heaters. Back to Top
18. How should preheat be measured? AWS D1.1 Structural Steel
Welding Code, Section 5.6 states: Preheat and all
subsequent minimum interpass temperatures shall be maintained
during the welding operation for a distance at least equal to the
thickness of the thickest welded part, but not less than 3 in.
[75mm] in all directions from the point of welding. In general,
when preheat is specified, the entire part should be thoroughly
heated so the minimum temperature found anywhere on that part will
meet or exceed the specified preheat temperature. Back to Top 19.
What is interpass temperature? Interpass temperature refers to the
temperature of the steel just prior to the depositing of an
additional weld pass. It is identical to preheat, except that
preheating is performed prior to any welding. When a minimum
interpass temperature is specified, welding should not be performed
when the base plate is below this temperature. The steel must be
heated back up before welding continues. A maximum interpass
temperature may be specified to prevent deterioration of the weld
metal and heat affected zone properties. In this case, the steel
must be below this temperature before welding continues. Back to
Top 20. Do I need an oven to store low hydrogen electrodes? All
low-hydrogen consumables must be dry to perform properly. Unopened
Lincoln hermetically sealed containers provide excellent protection
in good storage conditions. Once cans are opened, they should be
stored in a cabinet at 250-300F (121-149C). When the electrodes are
exposed to the air, they will pickup moisture and should be
redried. Electrodes exposed to the air for less than 1 week with no
direct contact with water should be redried as follows: E7018:
E8018, E9018, E10018, E11018: 1 hour at 650-750F 1 hour at
700-800F
If the electrodes come in direct contact with water or have been
exposed to high humidity, they should be predried for 1-2 hours at
180-220F first before following the above redrying procedure.
Standard EXX18 electrodes should be supplied to welders twice per
shift. Low hydrogen electrodes with the suffix "MR" have a moisture
resistant coating and may be left out up to 9 hours or as specified
by code requirements.
Back to Top
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AWS Classifications Explained
The American Welding Society (AWS) numbering system can tell a
welder quite a bit about a specific stick electrode including what
application it works best in and how it should be used to maximize
performance. With that in mind, let's take a look at the system and
how it works. The prefix "E" designates an arc welding electrode.
The first two digits of a 4-digit number and the first three digits
of 5-digit number indicate tensile strength. For example, E6010 is
a 60,000 psi tensile strength electrode while E10018 designates a
100,000 psi tensile strength electrode. E Electrode 60 Tensile
strength 1 Position "10" Type of Coating and Current
The next to last digit indicates position. The "1" designates an
all position electrode, "2" is for flat and horizontal positions
only; while "3" indicates an electrode that can be used for flat,
horizontal, vertical down and overhead. The last 2 digits taken
together indicate the type of coating and the correct polarity or
current to use. See chart below: Digit 10 11 12 13 14 15 16 27 18
20 22 24 Type of Coating High cellulose sodium High cellulose
potassium High titania sodium High titania potassium iron powder
titania low hydrogen sodium low hydrogen potassium iron powder iron
oxide iron powder low hydrogen High iron oxide High iron oxide iron
powder titania Welding Current DC+ AC or DC+ or DCAC or DCAC or DC+
AC or DC- or DC+ DC+ AC or DC+ AC or DC+ or DCAC or DC+ AC or DC+
or DCAC or DCAC or DC- or DC+
28
Low hydrogen potassium iron powder
AC or DC+
As a welder, there are certain electrodes that you will most
likely see and use time and time again as you go about your daily
operations. A DC machine produces a smoother arc. DC rated
electrodes will only run on a DC welding machine. Electrodes which
are rated for AC welding are more forgiving and can also be used
with a DC machine. Here are some of the most common electrodes and
how they are typically used: E6010 DC only and designed for putting
the root bead on the inside of a piece of pipe, this is the most
penetrating arc of all. It is tops to dig through rust, oil, paint
or dirt. It is an allposition electrode that beginning welders
usually find extremely difficult, but is loved by pipeline welders
world-wide. Lincoln 5P+ sets the standard in this category. E6011
This electrode is used for all-position AC welding or for welding
on rusty, dirty, less-thannew metal. It has a deep, penetrating arc
and is often the first choice for repair or maintenance work when
DC is unavailable. The most common Lincoln product is Fleetweld 180
for hobby and novice users. Industrial users typically prefer
Fleetweld 35. E6013 This all-position, AC electrode is used for
welding clean, new sheet metal. Its soft arc has minimal spatter,
moderate penetration and an easy-to-clean slag. Lincoln Fleetweld
37 is most common of this type. E7018 A low-hydrogen, usually DC,
all-position electrode used when quality is an issue or for
hardto-weld metals. It has the capability of producing more uniform
weld metal, which has better impact properties at temperatures
below zero. The Lincoln products are typically Jetweld LH-78 or our
new Excalibur 7018. E7024 Typically used to make a large weld
downhand with AC in plate that is at least " thick, but more
commonly used for plate that is " and up. Lincoln has several
electrodes in this category that are called Jetweld 1, 2, or 3.
Other Electrodes Although not nearly as common, an electrode may
have additional numbers after it such as E8018-B2H4R. In this case,
the "B2" indicates chemical composition of the weld metal deposit.
The "H4" is the diffusible hydrogen designator, which indicates the
maximum diffusible hydrogen level obtained with the product. And
"R" stands for the moisture resistant designator to indicate the
electrode's ability to meet specific low moisture pickup limits
under controlled humidification tests.
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Creating High Quality Stick Welds: A User's Guide
by Harry Sadler, Applications Engineering, The Lincoln Electric
Company
Stick welding is the most common form of arc welding, but
creating a good weld may not be easy for the beginner. Unlike wire
welding where you basically "point and shoot," stick welding has a
higher skill level and requires mastery of certain techniques. This
article will offer tips that you can follow to increase your
chances of creating a high quality stick weld - right from the
start. It will also discuss how to troubleshoot problems and
correct them. Tips 1. Select Steel in the Normal Range Whenever
possible, select steel within the "normal range," these include
AISI-SAE 1015 to 1025 steels with 0.1 percent maximum silicon and
sulfur content under .035 percent. Selecting these steels will make
the stick welding process easier since they can be welded at fast
speeds with minimum cracking tendencies. If you are welding with
low-alloy steels and carbon steels with chemistry compositions
above the "normal range", they will have a tendency to crack,
particularly when welding on heavy plate and rigid structures.
Because of this, you should use special precautions. In addition,
steels with high sulphur and phosphorus contents are not
recommended for production welding. If they must be welded, use
small diameter, low hydrogen electrodes. Welding with a slow travel
speed will further keep the puddle molten allowing gas bubbles time
to boil out, creating a better-finished weld. 2. Choose a Joint
Position and Electrode that is Conducive to the Metal Joint
position can have a great affect on finished weld quality. When
welding on 10 to 18 gauge sheet steel, the fastest travel speeds
are obtained with the work positioned at a 45 to 75 degrees
downhill angle. Also, don't overweld or make a weld that is larger
than needed for joint strength - this may lead to burnthrough. For
welding mild steel plate with a thickness greater than or equal to
3/16", it is best to have the work positioned flat, because this
will make operator manipulation of the electrode the easiest.
Lastly, high carbon and low-alloy steel plate can
best be welded with the work in the level position. 3. Follow
Simple Principles for Joint Geometry and Fitup Joint dimensions are
chosen for fast welding speeds and good weld quality. Proper joint
geometry is based upon some simple principles: 1) Fitup must be
consistent for the entire joint. Since sheet metal and most fillet
and lap joints are tightly clamped for their entire length, gaps or
bevels must accurately be controlled over the entire joint. Any
variations in a given joint will force the operator to slow his or
her welding speed to avoid burnthrough and manipulate the electrode
to adjust for the fitup variation. 2) Sufficient bevel is required
for good bead shape and penetration; insufficient bevel prevents
the electrode from getting into the joint. For example, a deep,
narrow bead may lack penetration and has a strong tendency to
crack. 3) Sufficient root opening is needed for full penetration,
while excessive root opening wastes weld metal and slows welding
speed. It is important to note that the root opening must be
consistent with the diameter of the electrode being used. 4) A root
face or a backup strip is required for fast welding and good
quality. Feather edge preparations require a slow costly seal bead.
However, double V butt joints without a land are practical when the
seal bead cost is offset by easier edge preparation and the root
opening can be limited to approximately 3/32". In general, weld
seal beads on flat work with 3/16" E6010 at approximately 150 amps
DC+. Use 1/8" at approximately 90 amps DC+ for vertical, overhead,
and horizontal butt welds. For low hydrogen and seal beads, weld
with an EXX18 electrode at approximately 170 amps. 4. Avoid Buildup
and Overwelding Fillets should have equal legs and a nearly flat
bead surface. Buildup rarely should exceed 1/16". Extra buildup is
costly in material and time, adds little to weld strength and
increases distortion. For example, doubling the size of a fillet
requires four times as much weld metal. Also, it costs 2/3 more to
butt weld a " plate (single-V with 1/8" land and 1/32" root
opening) when the excess buildup approaches 1/8". 5. Clean the
Joint Before Welding To avoid porosity and attain the ideal weld
travel speeds, it is important to remove excessive scale, rust,
moisture, paint, oil and grease from the surface of joints. If such
elements cannot be removed, use E6010 (5P+) or E6011 (35 or 180)
electrodes to penetrate through the contaminants and deeply into
the base metal. Slow the travel speed to allow time for gas bubbles
to boil out of the molten weld before it freezes. 6. Choose the
Right Electrode Size Large electrodes weld at high currents for
high deposit rates. Therefore, use the largest electrode practical
to be consistent with good weld quality. But, electrode size may be
limited especially on sheet metal and root passes, where
burnthrough can occur. As a general rule, 3/16" is the maximum
electrode size practical for vertical and overhead welding, while
5/32" is the maximum size practical for low hydrogen. In addition,
joint dimensions sometimes limit the electrode diameter that will
fit into the joint.
Troubleshooting Weld Defects Here are some of the most common
stick welding problems and how to correct them. Spatter Although
spatter does not affect weld strength, it does create a poor
appearance and increases cleaning costs. There are several ways to
control excessive spatter. First, try lowering the current. Make
sure it is within the range for the type and size electrode you are
welding with and that the polarity is correct. Another way to
control spatter is to try a shorter arc length. If the molten metal
is running in front of the arc, change the electrode angle.
Finally, look for arc blow conditions (commonly referred to as a
wandering arc), and be sure the electrode is not wet. Undercutting
Undercutting is frequently just an appearance problem, but it can
impair weld strength when the weld is loaded in tension or
subjected to fatigue. To eliminate undercut, reduce current and
slow travel speed, or simply reduce size until you have a puddle
size you can handle. Then change the electrode angle so the arc
force holds the metal in the corners. Use a uniform travel speed
and avoid excessive weaving. Wet electrodes If polarity and current
are within the electrode manufacturer's recommendations but the arc
action is rough and erratic, the electrodes may be wet. Try dry
electrodes from a fresh container. If the problem recurs
frequently, store open containers of electrodes in a heated
cabinet. Wandering arc With DC welding, stray magnetic fields cause
the arc to wander from its aimed course. This is a greater problem
at high currents and in complex joints. To control a wandering arc,
the best option is to change to AC welding. If that doesn't work,
try using lower currents and smaller electrodes or reduce the arc
length. In addition, you can change the electrical path by shifting
the work connection to the other end of the piece or by making
connections in several locations. You may also do this by welding
toward heavy tacks or finished welds, using run-out tabs; adding
steel blocks to change work current path or tacking small plates
across the seam at the weld ends. Porosity Most porosity is not
visible. However, since severe porosity can weaken the weld, you
should know when it tends to occur and how to combat it. Begin by
removing scale, rust, paint, moisture and dirt from the joint. Be
sure to keep the puddle molten for a longer time to allow gases to
boil out before it freezes. If the steel has a low carbon or
manganese content, or a high sulfur (free machining steel) or
phosphorus content, it should be welded with a lowhydrogen
electrode. Sometimes the sulfur content of free machining steels
can be high enough to prevent successful welding. Minimize
admixture of base metal into weld metal by using low current and
fast travel speeds for less penetration. Or, try using a shorter
arc length. A light drag technique is recommended for low hydrogen
electrodes. For surface holes, use the same solutions that are used
for porosity. If you are using E6010 or 11 electrodes, make sure
that they are not too dry. Poor Fusion Proper fusion means the weld
must physically bond strongly to both
walls of the joint and form a solid bead across the joint. Lack
of fusion is often visible and must be eliminated for a sound weld.
To correct poor fusion, try a higher current and a stringer bead
technique. Be sure the edges of the joint are clean, or use an
E6010 or 11 electrode to dig through the dirt. If the gap is
excessive, provide better fitup or use a weave technique to fill
the gap. Shallow Penetration Penetration refers to the depth the
weld enters into the base metal, and usually is not visible. For
full- strength welds, penetration to the bottom of the joint is
required. To overcome shallow penetration, try higher currents or
slower travel. Use small electrodes to reach down into deep narrow
grooves. Remember to allow some gap at the bottom of the joint.
Cracking Cracking is a complex subject because there are many
different types of cracks that occur in different locations
throughout a weld. All cracks are potentially serious, as they can
lead to complete failure of the weld. Most cracking is attributed
to high carbon or alloy content, or high sulfur content in the base
metal. To control this cracking, try these tips: 1. Weld with low
hydrogen electrodes 2. Use high preheats for heavier plate and
rigid joints 3. Reduce penetration by using low currents and small
electrodes. This reduces the amount of alloy added to the weld from
melted base metal. 4. Fill each crater before breaking the arc 5.
On multiple pass or fillet welds, be sure the first bead is of
sufficient size and of flat or convex shape to resist cracking
until the later beads can be added for support. To increase bead
size, use slower travel speed and a short arc technique or weld 5
degrees uphill. Always continue welding while the plate is hot. 6.
Rigid parts are more prone to cracking. If possible, weld toward
the unrestrained end. Leave a 1/32" gap between plates for free
shrinkage movement as the weld cools. Peen each bead while it is
still hot to relieve stresses. Conclusion By following the tips
offered here, even a beginner can create a high quality weld. And,
if you are experiencing problems, being able to troubleshoot and
make corrections will also turn a beginning stick welder into a
professional in no time. Stick Electrodes Stainless Steel
Consumables Hardfacing Consumables
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How to Strike and Establish an Arc
Source: adapted from New Lessons in Arc Welding, The Lincoln
Electric Company, 1990
A welding arc is maintained when the welding current is forced
across a gap between the electrode tip and the base metal. A welder
must be able to strike and establish the correct arc easily and
quickly. There are two general methods of striking the arc: 1.
Scratching 2. Tapping The scratching method is easier for beginners
and when using an AC machine. The electrode is moved across the
plate inclined at an angle, as you would strike a match. As the
electrode scratches the plate an arc is struck. When the arc has
formed, withdraw the electrode momentarily to form an excessively
long arc, then return to normal arc length. (See Figure 1) In the
tapping method, the electrode is moved downward to the base metal
in a vertical direction. As soon as it touches the metal it is
withdrawn momentarily to form an excessively long arc, then
returned to normal arc length. (See Figure 2) The principal
difficulty encountered in striking the arc is "freezing," or when
the electrode sticks or fuses to the work. This is caused by the
current melting the electrode tip and sticking it to the cold base
metal before it is withdrawn from contact. The extra high current
drawn by the Figure 2 "Tapping" method of arc starting "short
circuit" will soon overheat an electrode and melt it or the flux,
unless the circuit is broken. Giving the electrode holder a quick
snap backward from the direction of travel will generally free the
electrode. If it does not, It will be necessary to open the circuit
by releasing the electrode from the holder. Warning: Never remove
your face shield from your face if the electrode is frozen. Free
the electrode with the shield in front of your eyes, as it will
"flash" when it comes loose.
Tip: Brush your work free of dirt and scale before you strike an
arc. To view Lincoln's outstanding line of stick welders click here
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Reprinted with permission from the September/October, 1997 issue
of Practical Welding Today magazine, copyright 1997 by The Croydon
Group, Ltd., Rockford, IL
Common Problems and Remedies for GMAW
In much the same way that the automatic transmission has
simplified the process of driving, Gas Metal Arc Welding (GMAW) has
simplified the process of welding. Of all welding methods, GMAW is
said to be one of the easiest to learn and perform. The main reason
is because the power source does virtually all the work as it
adjusts welding parameters to handle differing conditions; much
like the sophisticated electronics of an automatic transmission.
Because less skill is required, many operators are able to GMA weld
at an acceptable level with limited training. These same operators
run into trouble, however, when they begin creating inferior welds
and are unable to diagnose and correct their own problems. The
guidelines listed below will help even inexperienced operators
create high quality welds as well as offering tips for those who
have been using the GMAW process for a number of years. Most common
welding problems fall into four categories: I. Weld porosity, II.
Improper weld bead profile, III. Lack of fusion, and IV. Faulty
wire delivery related to equipment set-up and maintenance. I. Weld
Metal Porosity Porosity Problem #1: Improper Surface Conditions The
most common cause of weld porosity is an improper surface condition
of the metal. For example, oil, rust, paint or grease on the base
metal may prevent proper weld penetration and hence lead to
porosity. Welding processes that generate a slag such as Shielded
Metal Arc Welding (SMAW) or Flux-Cored Arc Welding (FCAW) tend to
tolerate surface contaminates better than GMAW since components
found within the slag help to clean the metals surface. In GMAW,
the only contamination protection is provided by the elements which
are alloyed into the wire. Remedies To control porosity, use a
deoxidizer within the wire such as silicon, manganese or trace
amounts of aluminum, zirconium or titanium. Wire chemistry can be
determined by referring
to the American Welding Society (AWS) wire classification
system. Test the various types of wire available to find the right
chemistry for a given application. To start, try the most common
wire type, ER70S-3 (Lincoln L50) which contains 0.9-1.4 percent
manganese and 0.45-0.75 percent silicon. If porosity is still
present in the finished weld, increase the amount of silicon and
manganese found in the wire by switching to an ER70S-4 (Lincoln
L54) or an ER70S-6 which has the highest levels of silicon (0.8
-1.15 percent) and manganese (1.4-1.8 percent). Some operators
prefer to use a triple deoxidizer such as ER70S-2 (Lincoln L52)
which contains aluminum, zirconium or titanium in addition to the
silicon and manganese. In addition to changing the wire, further
prevent porosity by cleaning the surface of the metal with a
grinder or chemical solvents (such as a degreaser.) A word of
caution though if using solvents, be certain not to use a
chlorinated degreaser such as trichlorethylene near the welding arc
-- the fume may react with the arc and produce toxic gases.
Porosity Problem #2: Gas Coverage The second leading cause of
porosity in welds is a problem with the shielding gas coverage. The
GMAW process relies on the shielding gas to physically protect the
weld puddle from the air and to act as an arc stabilizer. If the
shielding gas is disturbed, there is a potential that air could
contaminate the weld puddle and lead to porosity. Remedies
Shielding gas flow varies depending on wire size, amperage,
transfer mode and wind speed. Typical gas flow should be
approximately 30-40 cubic feet per hour. Using a flow meter, check
that the shielding gas flow is set properly. There are a variety of
flow meters on the market today ranging from simple dial gauges to
ball flows all the way up to sophisticated, computerized models.
Some operators mistakenly think that a pressure regulator is all
that is needed, but the pressure meter will not set flow. A pure
carbon dioxide shielding gas requires the use of special flow
meters designed specifically for carbon dioxide. These special flow
meters are not affected by the frosting that may occur as the
carbon dioxide changes from liquid form to a gas. If high winds are
blowing the shielding gas away from the puddle, it may be necessary
to erect wind screens. According to the AWS Structural Welding
Code, it is advisable not to GMA weld when wind speeds are greater
than 5 mph. Indoors, ventilation systems may hamper gas coverage.
In this case, redirect air flow away from the puddle. If fume
extraction is necessary, use equipment designed specifically for
this purpose such as MAGNUM Extraction Guns from Lincoln Electric
-- they will remove the fume, but not disturb the shielding gas. A
turbulent flow of gas as it exits the gun may also lead to porosity
problems. Ideally, the gas will lay over the weld puddle much like
a blanket. Turbulent gas flow can be caused by too high a flow, an
excessive amount of spatter inside the gun nozzle, or spatter
build-up in the gas diffuser. Other possible causes of insufficient
gas flow may be damaged guns, cables, gas lines, hoses or loose gas
fittings. These damaged accessories may create what is referred to
as a venturi effect where air is sucked in through these openings
and flow is reduced. Lastly, welding with a drag or backhand
technique can lead to gas coverage problems. Try to weld with a
push or forehand technique which lays the gas blanket out ahead of
the arc and lets the gas settle into the joint.
Porosity Problem#3: Base Metal Properties Another cause of weld
porosity may be attributed simply to the chemistry of the base
metal. For instance, the base metal may be extremely high in sulfur
content. Remedy Unfortunately, if the problem with porosity lies
within the base metal properties, there is not much that can be
done. The best solution is to use a different grade of steel or
switch to a slaggenerating welding process. II. Improper Weld Bead
Profile If operators are experiencing a convex-shaped or
concave-shaped bead, this may indicate a problem with heat input or
technique. Improper Bead Problem #1: Insufficient Heat Input A
convex or ropy bead indicates that the settings being used are too
cold for the thickness of the material being welded. In other
words, there is insufficient heat in the weld to enable it to
penetrate into the base metal. Remedies To correct a problem with
running too cold, an operator must first determine if the amperage
is proper for the thickness of the material. Charts are available
from the major manufacturers, including Lincoln Electric, that
provide guidelines on amperage use under varying conditions. If the
amperage is determined to be high enough, check the voltage.
Voltage that is too low usually is accompanied by another telltale
sign of a problem: a high amount of spatter. On the other hand, if
voltage is too high, the operator will have problems controlling
the process and the weld will have a tendency to undercut. One way
to check if the voltage is set properly is to test it by listening.
A properly running arc will have a certain sound. For instance, in
short arc transfer at low amperages, an arc should have a steady
buzz. At high amperages using spray arc transfer, the arc will make
a crackling sound. The arc sound can also indicate problems -- a
steady hiss will indicate that voltage is too high and the operator
is prone to undercut; while a loud, raspy sound may indicate
voltage that is too low. Improper Bead Problem #2: Technique A
concave or convex-shaped bead may also be caused by using an
improper welding technique. For example, a push or forehand
technique tends to create a flatter bead shape than a pull or
backhand technique. Remedy For best bead shapes, it is recommended
to use a push angle of 5-10 degrees. Improper Bead Problem #3:
Inadequate Work Cable Problems with the work cable can result in
inadequate voltage available at the arc. Evidence of a work cable
problem would be improper bead shape or a hot work cable. Remedy
Work cables have a tendency to overheat if they are too small or
excessively worn. In replacing the cable, consult a chart to
determine size based on length and current being
used. The higher the current and longer the distance, the larger
the cable needed. III. Lack of Fusion If the consumable has
improperly adhered to the base metal, a lack of fusion may occur.
Improper fusion creates a weak, low quality weld and may ultimately
lead to structural problems in the finished product. Lack of Fusion
Problem: Cold Lapping in the Short Arc Transfer Process In short
arc transfer, the wire directly touches the weld pool and a short
circuit in the system causes the end of the wire to melt and detach
a droplet. This shorting happens 40 to 200 times per second. Fusion
problems may occur when the metal in the weld pool is melted, but
there is not enough energy left to fuse it to the base plate. In
these cases, the weld will have a good appearance, but none of the
metal has actually been joined together. Since lack of fusion is
difficult to detect visually, it must be checked by dye-penetrant,
ultrasonic or bend testing. Remedies: To guarantee correct fusion,
ensure that voltage and amperage are set correctly. If the operator
is still having problems after making those adjustments, it may
require a change in the welding technique. For example, changing to
a flux-cored wire or using the spray arc transfer method instead.
In spray arc transfer, the arc never goes out so cold lapping and
lack of fusion are not issues. Spray arc welding takes place at
amperages high enough to melt the end of the wire and propel the
droplet across the arc into the weld puddle. IV. Faulty Wire
Delivery If the wire is not feeding smoothly or if the operator is
experiencing a chattering sound within the gun cable, there may be
a problem with the wire delivery system. Most of the problems
related to wire delivery are attributed to equipment set-up and
maintenance. Faulty Wire Delivery Problem #1: Contact Tip There is
a tendency among operators to use oversized tips, which can lead to
contact problems, inconsistencies in the arc, porosity and poor
bead shape. Remedies: First, make sure that the contact tip in the
gun is in working order and sized appropriately to the wire being
used. Visually inspect the tip and if it is wearing out (becoming
egg-shaped), it will need to be replaced. Faulty Wire Delivery
Problem #2: Gun Liner A gun liner, like the contact tip, must be
sized to the wire being fed through it. It also needs to be cleaned
or replaced when wire is not being fed smoothly. Remedy: To clean
the liner, blow it out with low-pressure compressed air from the
contact tip end, or replace the liner. Faulty Wire Delivery Problem
#3: Worn Out Gun Inside the gun are very fine strands of copper
wire that will eventually break and wear out with time.
Remedy: If the gun becomes extremely hot during use in one
particular area, that is an indication that there is internal
damage and it will need to be replaced. In addition, be certain
that the gun is large enough for the application. Operators like to
use small guns since they are easy on the hand, but if the gun is
too small for the application, it will overheat. Faulty Wire
Delivery Problem #4: Drive Roll Drive rolls on the wire feeder
periodically wear out and need to be replaced. Remedies: There are
usually visual indications of wear on the grooves of the rolls if
replacement is necessary. Also, make sure that the drive roll
tension is set properly. To check tension, disconnect the welding
input cable from the feeder or switch to the cold feed option. Feed
the wire and pinch it as it exits the gun with the thumb and
forefinger. If the wire can be stopped by pinching, more drive roll
tension is needed. The optimum tension will be indicated by feeding
that is not stopped while pinching the wire. If the drive roll
tension is too high, it may deform the wire leading to birdnesting
(tangling) and a burn back (when the arc climbs the wire and fuses
the wire to the contact tip.) Make sure that the drive rolls and
the guide tube are as close together as possible. Next, check the
path from where the wire leaves the reel to where it enters the
drive rolls. The wire must line up with the incoming guide tubes so
there is no scrapping of the wire as it goes through the tube. On
some wire feeders, the wire spool position is adjustable -- align
it so that it makes a straight path into the tube. Faulty Wire
Delivery Problem #5: Wire Coming Off Reel and Tangling Some wire
feeding problems occur because the inertia from the wire reel
causes it to coast after the gun trigger is released. Remedy: If
the reel continues to coast, the wire on the reel will loosen and
the wire may come off or become tangled. Most wire feeding systems
have an adjustable brake on the wire reel. The brake tension should
be set so that the reel does not coast. By following these four
guidelines, a GMAW operator new to the world of welding or even
someone more experienced should have an easier time diagnosing
problems before they affect the quality of the work.
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Developed by The Lincoln Electric Company
Frequently Asked MIG Welding Questions
Here are some of the most frequently asked questions that The
Lincoln Electric Company receives regarding general MIG welding
issues.q q q q q
Does my choice of MIG welding wire really affect the quality of
the weld? Does shielding gas affect the quality of the finished
weld? Are there any other tips you can provide for higher quality
MIG welding? How important is a good electrical ground in MIG
welding? How important is the Contact Tip in MIG welding?
Q: Does my choice of MIG welding wire really affect the quality
of the weld? A: While there are many options on the market today
for mild steel welding wire, we will concentrate on the two most
popular for small shops or hobbyists. Lincoln Electric offers
several types of its copper-coated SuperArc MIG wire - including
the popular L-50 and L-56. Although both are 70,000 lb. tensile
strength wires designed for welding mild or carbon steels, it is
the amount of deoxidizers found in the wires that sets them apart.
SuperArc L-50 (AWS classification ER70S-3) is a great general
fabrication MIG wire and it usually allows you to make quality
welds on clean steel. For production work, .035, and .045 are the
most common diameters. However, you may want consider SuperArc L-56
when you need to weld steels that have less than perfect surface
conditions. In the same way you can upgrade gasoline for your
automobile from regular to premium for enhanced performance, you
can do the same for welding wire. For this reason, SuperArc L-56
wire (AWS classification of ER70S-6) carries more deoxidizers in
its chemistry. This means that it has more built-in cleaning action
to handle contaminants of welding such as surface rust, oil, paint
and dirt. With L-56, you may not be required to do as much cleaning
of the steel before welding. This higher quality of cleaning
offered by the deoxidizers usually translates into a higher quality
weld materials with less than stellar surface conditions. Most
automotive manufacturers now mandate this type of
wire for any automotive repairs. In addition, this wire is
available in diameters ranging from .025 to 1/16 which meet the
welding performance demands of thin sheet metal (24 gage) to heavy
plate welding. TRY SUPER ARC L-56! For more information on SuperArc
Products Click Here SuperArc/SuperArc MIG Wire -- Order Bulletin
C4.10 Q: Does shielding gas affect the quality of the finished
weld? A: For most mild steel applications, CO2 will provide
adequate shielding, but when you must have a flatter bead profile,
less spatter or better wetting action, you may want to consider
adding 75 to 90% argon to your CO2 shielding gas mix. Why? Argon is
essentially inert to the molten weld metal and therefore will not
react with the molten weld metal. When CO2 is mixed with Argon, the
reactivity of the gas is reduced and the arc becomes more stable.
But, Argon is more expensive. In production welding, selecting the
perfect shielding gas can be a science of its own. Attributes such
as material thickness, welding position, electrode diameter,
surface condition, welding procedures and others can affect
results. Common gas mixes for the home hobbyist and small
fabricator would be:q
100% CO2 -Lowest price, generally greatest penetration, and
higher levels of spatter. Limited to short circuit and globular
transfer. 75% Argon - 25% CO2 -Higher price, most commonly used by
home hobbyist and light fabricator, lower levels of spatter and
flatter weld bead than 100% CO2. Limited to short circuit and
globular transfer. 85% Argon - 15% CO2-Higher price, most commonly
used by fabricators, with a good combination of lower spatter
levels and excellent penetration for heavier plate applications and
with steels that have more mill scale. Can be used in short
circuit, globular, pulse and spray transfer. 90% Argon - 10% CO2-
Higher price, most commonly used by fabricators, with a good
combination of lower spatter levels and good penetration for a wide
variety of steel plate applications. Can be used in short circuit,
globular, pulse and spray transfer.
q
q
q
TRY C-25 SHIELDING GAS (75% Argon, 25% CO2 ) Q: Are there any
other tips you can provide for higher quality MIG welding? A: Try a
smaller diameter wire. Although the most common diameters of
welding wire are .035 and .045, a smaller diameter wire usually
will make it easier to create a good weld. Try an .025 wire
diameter, which is especially useful on thin materials of 1/8 or
less. The reason? Most welders tend to make a weld that is too big
- leading to potential
burnthrough problems. A smaller diameter wire welds more stable
at a lower current which gives less arc force and less tendency to
burn through. If you keep your weld current lower, you will have a
greater chance of success on thinner materials. This is a good
recommendation for thinner materials; but be careful using this
approach on thicker materials (>3/16) because there may be a
risk of lack of fusion. Whenever a change like this is made, always
verify the quality of the weld meets its intended application. TRY
SuperArc .025" L-56! For more information on SuperArc Products
Click Here SuperArc/SuperArc MIG Wire -- Order Bulletin C4.10 Q:
How important is a good electrical ground in MIG welding? A: In arc
welding, an arc is established from the electrode to the workpiece.
To do this properly, the arc requires a smooth flow of electricity
through the complete electrical circuit, with minimum resistance.
If you crimp a garden hose while watering the lawn, the flow at the
sprinkler head is much reduced. Beginning welders often make the
mistake of attaching the work clamp (or electrical ground) to a
painted panel or a rusty surface. Both of these surfaces are
electrical insulators and do not allow the welding current to flow
properly. The resulting welding arc will be difficult to establish
and not very stable. Other telltale signs of an improper electrical
connection are a work clamp that is hot to the touch or cables that
generate heat. Another key point to consider when attaching the
welding ground is to place the welding ground on the piece being
welded. Welding current will seek the path of least resistance so
if care is not taken to place the welding ground close to the arc,
the welding current may find a path unknown to the operator and
destroy components unintended to be in the welding circuit. SO . .
. FIRMLY ATTACH WORK CABLES TO CLEAN BARE METAL AND CLOSE TO THE
WELDING ARC. To receive additional safety information Click Here Q:
How important is the Contact Tip in MIG welding? A: Very important.
Make sure the gun tip isnt worn out or that weld spatter is not on
the tip near the exit hole. The contact tip in the gun should be
perfectly round and just a few thousandths larger than the wire
itself. Worn tips are typically oval and can cause an erratic arc
from the random electrical connection and physical movement of the
wire inside the worn tip. Genuine Lincoln contact tips are
precisely made from a wear-resistant copper alloy for superior
welding performance. If the contact tip enters the molten weld
pool, it should be immediately replaced. For most casual welders, a
good rule of thumb to assure high quality welding is to change the
tip after ever 100 lbs. of wire. Another point to remember about
contact tips is that they should always be threaded completely into
the gas diffuser and tightened prior to welding to give a smooth
flow of welding current. IF THE CONTACT TIP LOOKS QUESTIONABLE, GET
A NEW LINCOLN TIP, THREAD IT COMPLETELY INTO THE GAS DIFFUSER AND
TIGHTEN.
To view or order our MIG / MAG Welding Guide -- Order Bulletin
C4.200 Conclusion: The Lincoln Electric Company offers a full range
of MIG solutions Take a look at our equipment like the mid-sized
PowerMIG 255, the Waveform Control TechnologyTM tour de force named
the PowerWave 455, and rugged, adaptive Series 10 wire feeders
capable of MIG pulsing. Even more importantly, try for yourself the
consistent quality and feedability of our SuperArc copper-coated
and SuperGlide bare mild steel wires, the carefully crafted Blue
Max Stainless MIG wires and the wide range of aluminum SuperGlaze
MIG wires now available. In addition to products, we at Lincoln
take pride in our MIG welding expertise and application assistance.
If you have a question regarding our MIG solutions for your
application, please contact us via phone at 1.888.921.9353 or via
e-mail.
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MIG vs. Flux-Cored: Which Welding Process Is Right for You?
You are about to make the plunge and buy your first wirefeed
welder. Being a toolguy (or gal), you don't want to waste your
money on a toy that goes out with the trash in a few weeks. You
most likely are very comfortable building things from wood, but you
always wanted to step up to steel. You probably want to run it off
of 115 volt input, so that it is very portable, but maybe stepping
up to the 230 volt input machines with the option of welding
thicker material(more than ") is a valid point. You think the
decisionmaking process is over when you are hit with yet another
question - which welding process will you use? . . . GMAW (MIG) or
FCAW (fluxcored)? If you are like most novice welding operators,
you may be confused as to the differences of these two choices. The
best answer depends on 3 things. First, what you are welding.
Second, where are you welding it. And Third, the surface finish of
what you are welding. We will help you to decipher between the two
processes, then describe advantages and disadvantages of each and
wrap up by giving you usage tips. Ultimately, we hope to help you
decide on a solution that will give you the best results for your
application. The suggestions here are conservative and should be
attainable by a beginner. Welding is a skill and an art about 95%
can learn to do. Very few baseball players are able to hit over
.350 in the majors. Very few welders have the skills to make
picture perfect welds. It is critical to have good eye/hand
coordination and a steady hand. Arc practice time is the only
instructor that will teach you to truly set the machine properly.
With basic motor skills, practice and patience, you should attain
success at making sound welds. The Definitions Gas Metal-Arc
Welding: (GMAW) as identified by the American Welding Society, is
also popularly known as MIG (Metal Inert Gas) and uses a continuous
solid wire electrode for filler metal and an externally supplied
gas(typically from a high-pressure cylinder) for shielding. The
wire is usually mild steel, typically copper colored because it is
electroplated with a thin layer of
copper to protect it from rusting, improve electrical
conductivity, increase contact tip life and generally improve arc
performance. The welder must be setup for DC positive polarity. The
shielding gas, which is usually carbon dioxide or mixtures of
carbon dioxide and argon, protects the molten metal from reacting
with the atmosphere. Shielding gas flows through the gun and cable
assembly and out the gun nozzle with the welding wire to shield and
protect the molten weld pool. Molten metal is very reactive to
oxygen, nitrogen and hydrogen from the atmosphere, if exposed to
it. The inert gas usually continues to flow for some time after
welding to keep protecting the metal as it cools. A slight breeze
can blow the shielding away and cause porosity, therefore welding
outdoors is usually avoided unless special windscreens are erected.
However, if done properly, operator appeal and weld appearance are
excellent with MIG and it is most welders' favorite process to use.
Good technique will yield excellent results. The properly made
finished weld has no slag and virtually no spatter. A "push" gun
angle is normally used to enhance gas coverage and get the best
results. If the material you are welding is dirty, rusty, or
painted it must be cleaned by grinding until you see shiny bare
metal. MIG welding may be used with all of the major commercial
metals, including low carbon steel, low alloy steel, and stainless
steel and aluminum with potential for excellent success by a
novice. Aluminum MIG Welding aluminum requires much more than just
changing to aluminum wire. Get comfortable welding steel first.
Since aluminum is very soft, it requires aluminum drive rolls that
have a U-groove and no teeth to bite or cause wire flaking.
Cleanliness of the wire and base metal are critical. Wipe the
material with acetone on a clean shop rag. Use stainless steel wire
brushes that have only been used on aluminum. Drive roll tension
and gun length must be minimized. A Teflon, nylon or similar gun
liner is needed to minimize friction in feeding the wire and 100%
pure Argon gas is required for shielding. Special contact tips are
often recommended. Special gun movement techniques are often highly
desirable. It is a challenge, but it can be done. Self-shielded
Flux-Cored Arc-Welding process (FCAW per the American Welding
Society), or flux-cored for short, is different in that it uses a
wire which contains materials in its core that, when burned by the
heat of the arc, produce shielding gases and fluxing agents to help
produce a sound weld, without need for the external shielding gas.
We achieve a sound weld, but in a very different way. We have
internal shielding instead of external shielding. The shielding is
very positive and can endure a strong breeze. The arc is forceful,
but has spatter. When finished, the weld is covered with a slag
that usually needs to be removed. A "drag" angle for the gun is
specified which improves operator visibility. The settings on the
wirefeeder / power source are slightly more critical for this
process. Improper technique will have results that are magnified.
This type of welding is primarily performed on mild steel
applications outdoors. The Innershield .035" NR-211MP is often used
for the 115 volt machines and the .045" Innershield NR-211MP is
typically used in the 230 volt machines. Farmers have found that
these products can save a planting or harvest by repairing a broken
machine out in the middle of the field in record time. General
Usage Rules
MIG As a rule of thumb, it is recommended to use a compact
115volt input (or 230 volt) MIG wirefeeder/welder indoors on clean
new steel that is 24 to 12 gauge thick. 12 gauge is a little less
than 1/8" thick.