GMAW: GMAW vs FCAW-S Process Comparison
You are about to make the plunge and buy your first wire feeder welder and 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 ¼") is a valid point. You think the decision-making process is over when you are hit with yet another question - which welding process will you use? GMAW (MIG) or FCAW (flux-cored)? 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.
Gas Metal-Arc Welding
GMAWas 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
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
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 wire feeder welder 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-211-MP is often used for the 115 volt machines and the .045" Innershield NR-211-MP 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
As a rule of thumb, it is recommended to use a compact 115 volt input (or 230 volt) MIG wire feeder welder indoors on clean new steel that is 24 to 12 gauge thick. 12 gauge is a little less than 1/8" thick. 24 gauge is less than 1/16" thick. The smallest wire (.025") will make it the easiest to weld the thinnest (24 gauge) material. The .030" diameter wire will weld a little faster deposition rate. If you need to weld 1/8" to ¼" thick material with MIG, you will need the higher capacity compact machine which will require 230 volt input. The higher amperage range of this machine can better handle your welding needs in a single pass and you may not have to waste time with second or third passes. The 230 volt machine could also run .035" diameter wire. To MIG weld material more than ¼" thick, you need a higher capacity truly industrial machine. If most of your welding will be performed indoors on clean material that is less than 1/8" thick, a MIG machine that operates on 115 volts is probably your best bet for economic reasons in that a 230 volt input machine will be more expensive.
The flux-cored process is only recommended on materials as thin as 20 gauge, a bit thicker than the 24 gauge we said for MIG. In general, this process is best for welding thicker materials with a single pass, especially if you need to weld outdoors such as to repair a tractor out in the field. A 115 volt flux-cored machine using an electrode such as .035" Innershield NR-211-MP will generally allow you to weld steel up to ¼"thick. Note that this is more than double the thickness maximum of 12 gauge with MIG on 115 volts. With the proper electrode on a proper machine, such as .045" Innershield NR-211MP, and a 230 volt input machine, you can weld steel up to 1/2" thick. Note that Innershield® NR-211-MP requires that the machine be setup for DC negative polarity.
Advantages and Disadvantages
While there are advantages and disadvantages to both processes, we will try to outline for you some of the most common.
The best choice when cosmetic appearance is an issue since it provides lower spatter levels than flux-cored. The arc is soft and less likely to burn through thin material
The lower spatter associated with MIG welding also means no slag to chip off and faster cleaning time
MIG welding is the easiest type of welding to learn and is more forgiving if the operator is somewhat erratic in holding arc length or providing a steady travel speed. Procedure settings are more forgiving
If you are skilled and get specific proper guns, shielding gas, liners, drive rolls, and electrode, MIG can weld a wider range of material including thinner materials and different materials such as stainless, nickel alloys or aluminum
Since a bottle of external shielding gas is required, MIG welding may not be the process of choice if you are looking for something that offers portability and convenience. MIG also requires additional equipment such as a hose, regulator, solenoid (electric valve) in the wire feeder and flowmeter
The welder's first job is to prepare the surface by removing paint, rust and any surface contamination
MIG has a soft arc which will not properly weld thicker materials (10 gauge would be the maximum thickness that MIG could soundly weld with the 115 volt compact wire feeder welder we are referring to or ¼" with the 230 volt input compact wire feeder welder.) As the thickness of the material (steel) increases, the risk of cold lapping also increases because the heat input needed for good fusion is just not possible with these small machines
The Self-Shielded electrodes are optimal for outdoor procedures since the flux is built into the wire for positive shielding even in windy conditions. An external shielding gas and additional equipment are not needed, so setting up is simpler, faster and easier
The flux-cored process is most suited for applications with thicker materials as it is less prone to cold lapping
It is not recommended for very thin materials (less than 20 gauge)
When flux-cored welding, machine settings need to be precise. A slight change in a knob position can make a big difference in the arc. In addition, the gun position is more critical in that it must be held consistently, and at the proper angle, to create a good weld
This process creates spatter and slag that may need to be cleaned for painting or finishing
It should be noted that the same machine can be used to weld with both MIG and flux-cored processes though a special package is usually needed to change from one application to the other. Drive rolls, shielding gas, gun liners, contact tips and procedure settings need to be addressed when changing processes
Another area that may cause the novice welder some concern is how to choose the best wire. Proper electrode diameter is related to plate thickness and the welder you have. A smaller wire makes it easier to weld thinner plate.
For a 110 volt input MIG machine, an electrode such as Lincoln's .025" SuperArc® L-56 is the smallest available size and the easiest to use on very thin material. A .030" SuperArc would weld slightly thicker material a little faster. For flux-cored, a 110v machine would run a .035" wire (such as Lincoln's Innershield NR-211-MP) because this is the smallest size made and this is all the machine can run.
For a 230v MIG machine, most people are welding heavier plate and step up to the .030" or even .035" diameter solid electrode such as .030" or .035" SuperArc® L-56 because they deposit weld metal faster and they can weld heavier plate. For flux-cored with the 230 volt input machine, most people move up to Lincoln's .045" diameter Innershield NR-211-MP for plate up to ½" thick.
Realize that these small machines are excellent at what they do, but they cannot do everything. Electrodes for production welding, hardfacing to resist wear, and most specialty electrodes will exceed the capacity of these machines. You must be careful to match the output voltage of your machine with the voltage of the electrode and the appropriate wire diameter and wire feed speeds to make sure you have a compatible system.
Tips for All
It is very important to get a good, solid work connection. This means you should thoroughly clean or grind the surface of the metal where attaching the work clamp and use a tightly attached work clamp so electricity can easily flow through the workpiece and back to the welder. Paint and rust are insulators. Remove them. This is a very common mistake to overlook
Put the welder on a separate circuit breaker that is properly fused as stated in your Operators Manual. This is not another strand of Christmas lights. You are melting steel at around 5,000 degrees F. You cannot weld with inadequate input power. Don't even try
Good fit-up is a big plus. Weld joints are laps, fillets and butts. Avoid gaps whenever possible to minimize burnthrough problems. This is especially critical on thin sheet metal
Keep the gun cable as straight as possible for smooth wire feeding. Don't sharply bend it
Make sure the contact tip looks good (not elongated or melted) and it is tightened to the diffuser
Cut the wire at an angle to a point before starting to weld for better starts
Use correct electrode stickout and maintain it as well as proper welding procedures
Make sure the drive rolls feed smoothly with proper tension
Relax and try to hold the gun as steady and smooth as possible
Observe and follow all welding safety precautions as specified in your Operators Manual. Pay special attention to the potential for electric shock, arc rays that can burn skin and eyes, fire and explosion, and proper ventilation. For more details, consult ANSI Z 49.1
What is the difference between GMAW and FCAW process? ›
Difference Between GMAW and FCAW
GMAW is generally considered faster than FCAW because it uses a continuous wire feed instead of requiring manual loading of each electrode. Additionally, GMAW can be used in all positions, while FCAW cannot be used in vertical or overhead parts without special equipment.
The main benefits of FCAW-G over GMAW include improved out-of-position weld quality, deeper penetration, ability to join plates in the presence of contaminants and a wider selection of electrode materials. The increased electrode availability for FCAW-G includes a range of application-targeted consumables.What distinguishes FCAW S from all other arc welding processes? ›
While FCAW is quite similar to GMAW, the biggest difference is that it doesn't require you to have an external shielding gas. It revolves around a continuous wire feed process. There are two separate processes associated with flux-cored arc welding, one of which involves using shielding gas.What are two disadvantages of FCAW as compared to GMAW? ›
Disadvantages of FCAW:
Slower travel speeds compared to GMAW. Limited control over the welding process. More expensive consumables compared to GMAW.
FCAW-G processes provide double shielding. Self-shielded flux-cored arc welding. A type of FCAW that relies on the flux materials within a tubular wire electrode to provide shielding for the weld area. FCAW-S processes do not require external shielding gas.What is the difference between FCAW and MIG welding? ›
FCAW and MIG welding involve an electric arc that melts the base material to join the components. The main difference between the two is that FCAW utilizes an externally-fed wire that contains flux on its core, while MIG uses a solid wire electrode with no flux core.What are two advantages to using FCAW welding over other welding processes? ›
- A high deposition rate, which is the speed that the filler metal is applied.
- It can be used in all positions with the right filler metal.
- Suitable for outdoor welding or shop welding.
- Relatively easy to learn compared to other welding processes.
The Disadvantages of FCAW
A high level of noxious fumes which must be ventilated. Higher electrode wire cost compared to solid electrode wires. More costly equipment than many other welding processes. Less portable equipment than SMAW or GTAW.
- GMAW uses relatively complicated, expensive equipment compared to other processes.
- GMAW is less portable than SMAW.
- GMAW cannot be used in areas with a draft or outdoors since this would dissipate the shielding gas.
Flux-cored arc welding (FCAW) is a more economical alternative to shielded metal arc welding (SMAW), since it is a continuous-wire process and good, effective deposition rates can be achieved as a result of the inherently high duty cycle. The process also lends itself readily to mechanization.
What metal Cannot be welded with FCAW? ›
Which Metals Can Be Welded with FCAW? Flux cored arc welding works well with most carbon steels, cast iron, stainless steel and hard facing / surfacing alloys. However, nonferrous exotic metals, such as aluminium, cannot be welded using this welding technique.Which of the following is a benefit of the FCAW process? ›
The biggest advantage of using FCAW is its speed. Since the wire feeds continuously, welders can complete projects much faster than other welding methods, such as stick welding or gas tungsten arc welding (GTAW).What is the biggest disadvantage with FCAW G compared to GMAW? ›
There are limitations to FCAW-G compared to GMAW, particularly the need to clean slag in either single- or multipass applications. This may re- quire an additional step that can have an impact on productivity. Also, extra ventilation or personal protective equipment may be more critical to protect the welding operator.What are 3 advantages of GMAW welding? ›
- Deposition rates are higher compared to stick or TIG welding.
- The welding speed is higher, bringing higher productivity.
- It does not require post-weld finishing, since it does not generate slag.
- Minimal losses. ...
- Efficiency in welding execution time.
- Great value for money.
- Gas metal arc welding process requires no flux.
- GMAW can be adapted for manual and automatic operations.
- It requires no cleaning after the welding is done.
- Gas metal arc welding requires much less skilled welder for it operation.
The recommended polarity is DC+ for all types of wires. They are generally preferred for shop (i.e. inside) welding, as they have smoother arc characteristics. They can be used outside, but require extra precautions to prevent the wind from blowing away the shielding gas.Do you push or pull FCAW welding? ›
With flux-cored welding, you should always use a drag (pull) technique.What is the difference between the self shielded and gas shielded FCAW processes? ›
Gas-Shielded Flux-Cored Designed for use with CO2 or argon mixes, our gas-shielded, flux-cored wires deliver superior arc performance. Self-Shielded Flux-Cored Brings the productivity of wire welding to outdoor applications, with no shielding gas required.Does flux core wire penetrate better than MIG? ›
As we already discussed, flux-cored welding is a much better option when welding cast iron. It provides better penetration and welds than MIG, which can weld cast iron, but the welds would be weak.What is the advantage of MIG over flux core? ›
As the flux reaction produces slag, there is some spitting and sputtering, or spatter. With MIG wire, there is very little spatter and the resulting GMAW weld is the cleaner-looking option.
Is flux core welding as strong as MIG welding? ›
Welders will debate whether flux core welding or MIG welding provides a stronger weld until the end of time. The truth of it is that they are ultimately pretty similar. For most applications, both methods will provide a strong weld that will hold what it needs to.What is one advantage of the GMAW welding process over SMAW? ›
Due to its ability to lay down cleaner welds, GMAW promotes better efficiency. SMAW can leave slag deposits on the weld surface due to the vapourizing flux. The slag must be painstakingly removed once the weld has hardened, increasing the overall project duration. With GMAW, welds require less secondary cleaning.Is metal core welding better than FCAW? ›
Metal-cored wires are similar to flux-cored wires in that both types of filler metals have a tubular construction. However, metal-cored wires do not produce a slag that must be removed after each welding pass, resulting in a higher deposition efficiency and lesser post-weld cleaning as compared to flux-cored wires.What is considered an advantage of the GMAW process? ›
The main advantage of GMAW is its versatility. It can weld multiple metals, including steel, aluminum, stainless steel, and nickel alloys. The process also produces high-quality welds with minimal heat distortion or burn-through. This makes it ideal for more delicate projects where precision and accuracy are key.What are some common problems I might have while learning how to use FCAW? ›
- Defect: Burnback. ...
- Defect: Birdnesting. ...
- Defect: Slag Inclusions. ...
- Defect: Porosity. ...
- Defect: Too Much or Too Little Weld Penetration. ...
- Defect: Cracking.
In gas metal arc welding (GMAW) a common unwanted side effect is the creation of what welders call spatter. These are droplets of molten material that are produced near the welding arc. Spatter happens when welding currents are too high, incorrect polarity or if there is insufficient gas shielding.What are 3 weld defects common to GMAW? ›
- Porosity issues.
- Too much weld deposit.
- Improper weld penetration.
- Lake of fusion.
- Lack of uniformity.
Despite all these advantages the GMAW process also has some limitations. Sensitive to contaminants – the process can only handle low to moderate levels of surface contaminants such as rust, mill scale, dirt, oil and paint.What is the deposition rate of FCAW vs GMAW? ›
SAW and GTAW deposition efficiency (if using a filler metal) is around 99%; GMAW (solid and metal-cored wires) is between 92% and 98%, depending on shielding gas type and wire transfer mode; FCAW averages about 87%; and SMAW averages around 65%.What is the most productive welding process? ›
Gas metal arc welding is the most popular arc welding process in manufacturing facilities. It's high electrode efficiency and ability to deposit metal at a high rate make it a very attractive process for high productivity environments.
What is one advantage of the self shielded FCAW process? ›
Self-shielded flux-cored arc welding (FCAW-S) offers numerous benefits, including good weldability, high deposition rates, and excellent chemical and mechanical properties. These make the process a common choice for many applications, such as structural steel erection, bridge construction and heavy equipment repair.Can you weld stainless steel with FCAW? ›
Good reasons for using FCAW on stainless:
You need to weld stainless outside in windy conditions and are opposed to using an arc welder. You'll often have less splatter with a FCAW weld.
Flux core can be used with a variety of metals, including stainless steel and some nickel and steel alloys.Which is better GMAW or FCAW? ›
GMAW is generally considered faster than FCAW because it uses a continuous wire feed instead of requiring manual loading of each electrode. Additionally, GMAW can be used in all positions, while FCAW cannot be used in vertical or overhead parts without special equipment.Why is FCAW used instead of GMAW? ›
As compared to GMAW, FCAW electrode is costlier but it offers relatively deeper penetration and higher filler deposition rate per pass. However, FCAW is particularly suitable for joining ferrous metals. Both the welding processes can offer sound reliable joint requiring minimum effort.What is the advantage of GMAW over FCAW? ›
GMAW can weld a wide range of material types and thicknesses. It emits less welding fumes in comparison to SMAW and FCAW processes. GMAW has higher electrode efficiencies i.e. between 93% and 98%, compared to other welding processes.What is the most used GMAW? ›
Argon is most commonly used for GMAW on nonferrous metals. This single-atom gas has a low thermal conductivity and ionization potential which results in a low transfer of heat to the exterior of the arc. Because of this, Argon delivers a deep yet narrow weld penetration.What typically uses GMAW? ›
Although GMAW typically uses a constant voltage and direct current power system, the process also employs alternating current systems with a range of different amps and voltages and varying electrode diameters.Which 3 gases are most commonly used for GMAW? ›
The four most common gases used in GMAW welding are Argon, Helium, Carbon Dioxide (CO2) and Oxygen (O2).What are the 3 types of metal transfer for GMAW? ›
Three modes of metal transfer are possible with GMAW: short-circuiting transfer, globular transfer, and spray transfer. In addition, there is a variation of the spray transfer mode called pulsed spray.
How efficient is GMAW welding? ›
GMAW has higher electrode efficiencies, usually between 93% and 98%, when compared to other welding processes.What is the difference between FCAW and GTAW? ›
Gas Tungsten-Arc Welding (GTAW) is also known as Tungsten Inert Gas (TIG) welding that, unlike GMAW and FCAW, uses a non-consumable electrode made out of tungsten, meaning a separate filler wire or rod may be required.What is the process of FCAW welding? ›
Flux-Cored Arc Welding (FCAW) uses the heat generated by a DC electric arc to fuse the metal in the joint area. The arc is struck between a continuously fed consumable filler wire and the workpiece, melting both the filler wire and the workpiece in the immediate vicinity.What are the main differences between GMAW and GTAW? ›
GMAW, or gas metal arc welding, is a type of welding that uses an electric arc to heat the metal being welded. GTAW, or gas tungsten arc welding, is a similar process but uses a tungsten electrode instead of an electric arc.What is the main difference between GMAW and SMAW? ›
An SMAW electrode has an external flux covering (one reason why it is known as stick welding), whereas a GMAW electrode has an external shielding gas. Due to its ability to lay down cleaner welds, GMAW promotes better efficiency. SMAW can leave slag deposits on the weld surface due to the vapourizing flux.Which of the following is a similarity between FCAW and GMAW? ›
Which of the following is a similarity between FCAW and GMAW? Both use CP welding power supplies.Is the FCAW power supply the same type that is required for GMAW? ›
The FCA welding power supply is the same type that is required for GMAW, called constant-potential, constant-voltage (CP, CV). The words potential and voltage have the same electrical meaning and are used interchangeably.What are the two basic FCAW processes? ›
The FCAW process can be divided into two types depending on the shielding method; one that uses an external shielding gas and one that solely relies on the flux core itself for protecting the weld area.What is a disadvantage of FCAW welding? ›
Higher electrode wire cost compared to solid electrode wires. More costly equipment than many other welding processes. Less portable equipment than SMAW or GTAW. The slag covering the weld must be removed. Mechanical problems can lead to melted contact tips, irregular wire feed, or porosity of the ...
FCAW-G wires are similar in construction to self-shielded flux-cored arc welding (FCAW-S) wires, but do not generate enough of an inert atmosphere during welding to fully protect the weld. For this reason, it is necessary to use an external shielding gas with FCAW-G wires to achieve quality welds.
What electrode is the main difference between FCAW and GMAW? ›
GMAW employs a sloid wire-type electrode (diameter 2 – 5 mm). FCAW employs a hollow tubular electrode (diameter 0.9 – 3.2 mm). Based on the volume of the filler metal, GMAW electrode is cheaper.What is the difference between SMAW and GMAW and FCAW? ›
To sum it up, SMAW electrodes are solid with an external covering of flux, while FCAW electrodes are tubular with an inner flux core and an outer electrode shell. On the other hand, GMAW uses an externally supplied shielding gas, rather than flux.What is GMAW welding basics? ›
- Identify the Base Material. The best place for new welders to start is with the base metal. ...
- Select a Filler Metal. ...
- Set the Shielding Gas. ...
- Understand the Weld Parameters. ...
- Know Your Torch Angle. ...
- Master Your Travel Speed. ...
- Achieve Your Desired Bead Appearance, Quality.