|
Welding Help
A welder quite often isn't the most sought after tool by many
do-it-yourselfers. A welder can, however, be a very handy and
important tool for the contractor or those wishing to repair or
build metal projects around the home. Welders are a necessity
around the farm and ranch, as well as for those doing auto repair
work. Welding and welders may seem daunting to the first timer and,
indeed, welding can be challenging, requiring learned skills. These
days welding, however, isn't just for shop class nerds or
professional metalworkers; it can be fun, and any number of
modern-day tools make welding easier for even the first timer. Many
modern welders are also less expensive and don't require a special
220-volt circuit. Larger models do, however, require a 220-volt
circuit.
Types Available
Four basic welding tools and techniques are used: arc (stick),
MIG, TIG and oxygen/acetylene. Each welding technique has its
advantages and disadvantages
Stick welding has been the most popular method for most
home-shop welding for a long time. Stick welding uses an electric
current flowing directly between a gap between the metal and the
“stick” or arc-welding electrode. The current causes part of the
electrode to melt, allowing it to mix with the metal of the work
piece and form the weld. The electrode has a flux coating that
burns to form a protective shield around the arc. Stick welding is
the most effective method for welding many different alloys or
joints. Stick welding can be used outdoors or indoors or in drafty
areas, is the most economical method and will weld on rusty or
dirty metals.
Stick welding does have some disadvantages. It is limited to
metals no thinner than 18 gauge, requires frequent rod changing,
has lots of splatter and the welds must be cleaned up after they
are finished. Stick welding is also more difficult to learn and
use, particularly in striking and holding the arc. Arc welders are
available as either AC or DC or AC/DC. AC welders are the most
economical and are used for welding thicker metals of 1/16 inch or
more. They are the best choice for farmers, hobbyists, and home
maintenance chores. DC welders provide cleaner welds, fewer arc
outages, less splatter and sticking, and better control on thinner
metals. They are also more expensive.
MIG welding (GMAW) (also sometimes called wire-feed) uses
a wire welding electrode on a spool that is fed automatically at a
constant selected speed. The arc created by an electrical current
between the base metal and the welding wire melts the wire and
joins it with the base. This produces high-strength welds with a
very good appearance and little need for cleaning. MIG welding also
uses a gas shield process with gas fed through the welding torch
and acting as a shield at the arc. This prevents oxidation and
contamination of the base metal. The gas utilized may be inert or
active, depending on the base metal to be welded. MIG welding is
clean, easy and can be used on either thin or thicker plate
metals.
A similar type of wire-feed welding is FCAW. It is slightly
different from MIG welding in that it does not require a shielding
gas. This gas-free welding uses flux-cored welding wire to shield
the arc. This form of welding is the simplest, very efficient and
extremely effective, especially when welding outdoors in windy
conditions.
Both MIG and FCAW are very easy to learn and can create
super-clean welds on steel, aluminum and stainless. MIG and FCAW
weld materials as thin as 26 gauge.
Another form of welding is TIG, also called Heliarc. It
utilizes tungsten inert-gas and is used primarily by
professionals.
Oxygen/acetylene welding utilizes oxygen and acetylene
mixed at the torch to produce a flame hot enough to melt metal. It
can be used for metal cutting as well as welding purposes.
Oxygen/acetylene welding takes quite a bit of practice and skill,
as well as quite a bit of safety rules in storing and using the
gases.
Safety
Welding, like many work procedures, can be dangerous if you
don't follow safety rules.
1. Work in a safe area, free of all flammables, with both a fire
extinguisher and a bucket of sand available.
2. Exposure to a welding arc is extremely harmful to eyes and skin.
Prolonged exposure can cause blindness and burns. Never weld unless
you are adequately protected. Wear a heavy, long-sleeved shirt,
cuffless pants, high-topped shoes, flameproof welding gloves and a
protective welding helmet.
3. Read and understand the welder's owner's manual
Basic Practices
The following steps are the basics for MIG or arc welding. It's
extremely important that all metal surfaces to be joined are free
of rust, dirt, scale, oil and paint. If the surfaces are not
properly cleaned, the weld can be porous and brittle. Remove
oxidation and dirt with a steel-bristled wire brush. Remove all oil
or grease with a good cleaner.
Aluminum requires even more preparation. First, use a good
chemical aluminum cleaner. Aluminum has an anodized surface and
this must be wire brushed, sanded or ground off the surfaces to be
welded, as well as anywhere the ground clamp is to be placed
If joining thick metal pieces, they should first have their
edges beveled with a metal grinder. The angle of the bevel should
be approximately 60 degrees at the point of contact.
Connect the ground clamp to the work piece and as close as
possible to the area to be welded. On-board computer systems of
automobiles can be damaged if the ground clamp is connected
directly. Do not weld until you have disconnected the cable from
the battery that is attached to the chassis ground.
When first learning to weld, it's a good idea to practice on
scrap metal. Try different heat settings, base metal thicknesses
and welding positions for each type and size of wire you will be
using. Make sure you read and understand the owner's manual. Then
turn on the welder and follow the manufacturer's instructions on
tuning in the wire speed and heat settings.
Properly holding the gun is important for wire-feed welding. The
gun can be held in two basic methods, depending on the type of weld
being made. Because the welding tip is designed with the contact
tip recessed from the end of the nozzle and the nozzle electrically
insulated from the rest of the gun, wire-feed welding is easy to
learn. You can actually rest the nozzle on the work piece and drag
it along. This is very helpful for beginners. Stick welding
requires that you first touch the work to strike an arc, then lift
the electrode to prevent it from sticking and this takes some
practice and skill.
Wire-feed welding is really quite simple. Line the gun up in the
proper position on the joint to be welded. Lower your helmet or
hold up a welding shield and pull the trigger to start the arc. In
a second or two you'll notice a weld puddle beginning to form and
the base of the bead beginning to build. You can either push or
pull the gun to move it along the weld joint. When welding
aluminum, it's best to push the gun as this creates a cleaner
appearance. Move the gun steadily and at the right speed to create
a solid weld without lumps or an uneven bead. This part does take
some practice, but it's still easier than stick welding.
Stick welding begins by first selecting the proper electrode.
The electrode is basically a rod coated with flux. The type and
thickness of the metal and the position of the work piece
determines the electrode type and amount of heat needed
Naturally, the thicker metals require more heat. Welding
electrode and arc-welder manufacturers provide selection charts as
to the electrodes needed for specific chores. You must next select
the proper amperage for the electrode and the work piece. Turn on
the welder, set the amps, protect your eyes and strike the arc. It
is akin to striking a match, scratching the tip of the rod against
the work surface, and then quickly lifting it to the required
1/8-inch. This gap must then be maintained consistently during the
welding process. If the gap becomes too narrow the electrode will
stick to the work surface. If the gap becomes too wide the arc
stops. At the same time you are maintaining the proper distance,
you must also maintain a consistent rate of travel with the rod
along the joint to create a proper bead. Too fast and the joint
will be weak. Too slow and the bead will overbuild with more slag.
This does take practice, and it's best to practice on scrap
pieces.
Two types of beads are commonly used: stringer and weave. A
stringer bead is created by moving the gun in a fairly straight
line and keeping the nozzle and wire centered on the joint. This,
naturally, is the easiest bead to make. A weave bed is used when
you must deposit metal over a wider space than with a stringer
bead. This is made by waving the gun nozzle side to side while
moving along the weld.
Quite often, more than one bead is required to fill the V shape
ground into the joint, as well as to create a strong joint. If
using a stick welder, or a self-shielding, flux-core wire in a
wire-feed welder, you must chip and brush the slag off each bead
after it cools and before making another pass. This slag must also
be removed when the weld is finished.
Welders Available
Both stick and wire-feed welders are available in a wide range
of sizes, rated by the amperes they create. It's important to note
the duty-cycle when purchasing a welder. This is the percentage of
actual weld time that can occur in a ten minute interval. For
example with a 20% duty cycle, actual welding can only occur for
two minutes, and then the machine must cool for eight minutes.
Models such as those from Campbell Hausfeld feature a yellow lamp
on the front that lights if the duty cycle is exceeded. Stick
welders range from 50/70 amps up to 50/230 amps output. The smaller
welders are 115 volt, the larger welders require a 220-volt
circuit. The smaller welders will handle materials up to 1/8-inch
thick, while the larger welders can weld steel up to 3/8 inch in
one pass. I have a Lincoln Electric, Classic stick electrode welder
that is probably over 40 years old and still going strong. I've
welded everything from bicycles to tractors with it. Another good
arc welder for homeowners is the Schumacher 70-amp AC ARC welder.
It is fairly easy-to-use and has two heat settings. For more
experienced welders the Schumacher 230/140-amp AC/DC arc welder is
a good choice. It has an infinite heat-selection feature and the DC
output aids in welding hard-to-start positions. Campbell Hausfeld
offers a 70-amp AC and a 230-amp AC/DC model. Oxy-acetylene kits
are also available from Campbell Hausfeld.
Wire-feed welders range from 30/70 up to 30/85 in 115-volt,
220-volt models up to 200 amps. Wire-feed models are available as
flux-core or MIG. The former are the easiest to operate as they
require no gas. You can learn to weld in minutes. Many MIG units
are also available to weld with flux wire or with gas. This allows
you to learn to weld the easy way with the flux wire. Then simply
add the gas bottle for more advanced welding. An excellent example
is the Campbell Hausfeld, Model 115 MIG/Flux DC, wire-feed welder.
It comes complete with a roll of flux wire and a hand-held eye
shield. Simply assemble a few parts, install wire roll and start
welding. A wide range of welders, including arc, MIG, TIG and
oxygen/acetylene is available from Campbell Hausfeld and Lincoln
Electric. Craftsman has introduced several new MIG/flux
welders.
Many welders come with a hand-held welding shield. If you do
much welding you will appreciate a welding helmet. Auto darkening
models such as the Campbell Hausfeld model shown, make it easy to
see the beginning placement of the gun or stick, yet instantly
darken to protect your eyes.
Don't be afraid to tackle welding. Today's tools make the chore
easy for even a first-timer, and you'll probably find it's fun and
addictive
|