What is Welding?
Welding by definition is a process for joining similar metals. It basically joins metals by melting and fusing the metals being joined and the filler metal applied. Welding is a localized heat input and involves ferrous and non-ferrous based metals such as steel, stainless steel, and aluminum. Welding covers a wide temperature range that can reach up to 3000º F. Proper weld joints can be as strong as the base metals being joined. A form of welding is used in a majority of items you use and depend on in your day to day life. It ranges from the car you drive to the chair you sit on in your home. Therefore, welding is an important fixture in our culture.
What are the different types of Welding?
There are a number of different welding procedures. Here are the most common types welding.
Shielded Metal Arc Welding - (We will refer to it as SMAW)
This process is also known as manual metal arc or “MMA” welding. It is also informally called “Stick Welding”. SMAW uses a consumable electrode to support the arc of the weld, while the outer flux coating on the electrode is what acts as the shield when melted. The core of the electrode then becomes the actual filler metal when joining the items together. SMAW is best suited for doing welds where both the conditions around you as well as the metal itself, are not the best. I.E. - welding on rusty or dirty metal or in windy outdoor conditions. This is type of welding takes more practice than others and may be for a moderate to intermediate experienced welder.
Gas Metal Arc Welding- (referred to as GMAW)
This type of welding is sometimes referred to by its subtypes as metal inert gas or “MIG” welding and metal active gas or “MAG” welding, which uses a shielding gas to eliminate oxygen and impurities from forming in the molten weld or puddle. The gas is typically 75% Argon/25% Co2. MIG welding uses a welding machine that feeds the wire to the welding surface in either an automatic or semi-automatic manner. MIG welders continuously feed a consumable wire electrode and shielding gas through a welding gun. MIG welding is generally found to be one of the easier welding processes to learn. With practice MIG welding can be much easier to control on thinner metal (think body panels on a car) than some of the other welding processes. MIG welds often provide cleaner welds that require less clean up. Many MIG machines have the ability to also to do flux cored welding as described below. Both our Eastwood MIG 135 and 175 can do both types of welding effortlessly
Flux Cored Arc Welding (referred to as FCAW)
FCAW is an automatic or semi-automatic welding process in which continuously fed consumable electrode wire containing a flux and a constant voltage are used to join metals together. An externally supplied shielding gas is sometimes used, while more commonly the flux itself is relied upon as the proper protection from the atmosphere. This process is most popular in the construction industry because of its portability and high welding speed. As with stick welding, windy conditions or dirty, rusty metal are not as much of a concern when using the flux cored wire only. The welds as well are similar in that cleaning the welds afterwards can be quite time consuming. When using a separate shielding gas, this form of FCAW is often called “dual shield” welding. This is mostly used in heavy duty welding such as seen in the industrial fields. Both our Eastwood MIG 135 and 175 can do both types of welding effortlessly (FCAW and GMAW).
Gas Tungsten Arc Welding (referred to as GTAW)
GTAW commonly referred to as “TIG” welding is an arc welding process that uses a non-consumable tungsten electrode to produce the weld. This welding process uses an inert gas (normally 100% argon) for the shielding gas to protect the weld from the atmosphere. A filler metal is used to input in the weld joint.
Also, most TIG welding units contain a high frequency generator. GTAW is most commonly used to weld thin sections of stainless steel, aluminum, magnesium, copper alloys and other non-ferrous metals. GTAW gives the operator much more control over the settings to produce the weld. This normally can produce stronger, cleaner, higher quality welds. GTAW on the other hand, is far more complex and is best suited for experienced welders. This process is also much slower than other types of welding.
Resistance Spot Welding (referred to as RSW)
Spot Welding is a process in which two contacting metal surfaces are joined by the heat obtained from the resistance to electric current flow. Spot welding uses two pointed copper alloy electrodes to concentrate the welding current to a small “spot” and to clamp the work pieces together at the same time. Forcing a large current through the two pieces will melt the metal and form the weld. The nice feature of this process is that the welding process happens so quickly (normally about 10 milliseconds), and to such a small area, that the heat generated to the panel is very small, and thus keeps the panels from warping. The amount of heat delivered to the spot weld is determined by the resistance between the electrodes amplitude and duration of the current. Applying too little energy won’t melt the metal or will make a poor, weak weld. While on the other hand, applying too much energy will melt too much metal and often times make a hole in the metal, rather than a weld.
Basic tips when considering a welder.
What do you want to use the welder for primarily? (Farm, Fabrication, heavy production, automotive
Welders are designed for certain applications, depending on the output, duty cycle, and other features. For instance, if you plan to do the majority of your work outside on “weathered” metal, you may want to consider a welder such as a stick welder or flux core welder that does not require a shielding gas that can be blown out by wind.
Buy a welder that will meet or (ideally) surpass your needs. (do not “under buy”), if you could “EVER” see yourself having a need for a unit that has some features you do not currently need, it is best to step up to that unit. There is always room for growth. This is most notable when it comes to entry level flux core welders that do not allow for gas shielded MIG welding. If you need a flux core machine, it is often better to step up to the model that allows for both.
Do you need it to be portable? Will you be able to move the object you are welding to the welder? Running a long 220V extension cord across your yard to weld something can often decrease the voltage and produce inconsistent welds. If an electrical hook up isn’t going to be near the work area, you may need to consider a welder that can work with a gas powered welding generator. An 110V unit may suit some better since 110V outlets are more plentiful around the house. The same is true if you plan to weld more than just around your own property. Such as your friend that may not have a dedicated 220V outlet you can access when helping him with some welding in his garage.
Common Welding Terms
Arc Length - Refers to the gap between the end of the electrode and where the arc makes contact with the surface of the metal.
Backup Strip - A section of metal that is butted up to an open gap between two work pieces. Often times, backup strips are used behind a gap to avoid blowing through the metal. The backup strip can either be welded into place, or a metal with a high melting temperature can be held behind the gap while welding.
Brazing - A process in which a filler metal that is above 850F, but lower than the melting temperature of the parent metal is used to join pieces together.
Duty Cycle - The minutes out of a ten minute period in which an arc welder can operate the max rated output.
Electrode - A coated metal wire that has the same composition as the metal that is being welded.
Flash Burn - This is when the radiation produced by the ultra-violet rays from the welding arc burn your skin or your eyes. This is commonly called “welders flash”. Flash burn will have similar effects to sun burn on your skin, and will feel like you have sand in your eyes within 24 hours of being exposed. ALWAYS wear your welding helmet and protective clothing when you are welding, or near someone that is!
Flux - The coating on arc-welding rods and flux-cored welding wire. It is consumed in the arc to produce a shielding gas.
Ground Lead - The conductor cable between the welder and the metal you are welding.
Hard facing - Refers to a welding electrode or wire that is designed to add surface to an area rather than join two pieces of metal together. This is often times used on high-wear areas to allow for the surface to last longer when in constant contact with another surface. Commonly used on the buckets of excavating machines.
Rated Output - The amps and voltage the power source in the welder will produce for a given duty-cycle period.
Shielding Gas - Protective gas used to prevent contaminants from the atmosphere from getting in the weld pool. Normally this is a mixed gas or CO2.
Slag - A layer of flux soot protects the welds contaminants while the weld is cooling (or solidifying). Slag must be removed after the weld cools.
Spatter - Metal particles that are thrown while welding. Spatter often sticks to, and cools on the work piece and must be removed.
Stick Electrode - A stick of metal filler that has had the electrode covered by the necessary chemical or metallic chemicals to shield the weld from the atmosphere when welding. The stick also completes the electrical circuit and creates the arc necessary to weld with a stick welder.
Tungsten - A metallic element with an extremely high melting point used for manufacturing TIG electrodes.
Weld Pool - </strong>This is molten metal that is seen when welding metal together.
Wire Feed Speed - </strong>Refers to the amount of filler metal fed into a weld. The higher the wire feed speeds, the higher the amperage.
Common Types of welds.
The most common types of welds or joints are listed below. These are many times the best to choose from when welding 2 pieces of metal together.
Butt Weld - This weld is a joint between two plates or sections where the components are butted together and do NOT overlap or interlock. This is the most common joint used in the welding field. Sometimes jointing plates are fixed or welded to the panels to add additional strength.
Lap Joint - A joint in which the two metal parts are overlapped in a parallel plane.
Corner Joint - A joint where the two metal parts are to be joined at right angles to each other. These joints normally require a large amount of weld metal to allow for a strong weld.</p>
Edge Joint - This is a joint in which the surfaces of the two metals that are to be welded are parallel to one another, and the weld is made on the now common edge when they are butted.
Plug Weld - A joint where the weld is made through a circular hole that is in one of the pieces into the other part that is placed directly behind the hole.
Seam Weld - A continuous weld that is made between or on top of two overlapping metal parts.
Stitch Weld - A weld made between or upon two overlapping parts. Often times these are referred to as “spot welds”, although technically incorrect.
T Joint - A type of joint that is produced when two metal parts are perpendicular to each other and form the letter “T” when welded.