MIG Welding Without Gas
People keep asking us, is it possible to do mig welding without gas? Yes, it’s very much possible. By using a flux-cored wire. However, there’s a great difference between using gas for shielding and a gasless mig welding which is popularly known as flux-core welding. Flux core welding enables the welders to weld without the need to use any type of gas for any kind of metals. As carbon dioxide (CO2)and argon (Ar) are the two most usable forms of gas in MIG welding, it is the flux in the flux-cored wire that can make MIG welding possible without the use of gas.
So what is in the flux-cored wires that make mig welding without gas possible?
Flux-cored arc welding or FCAW uses two kinds of wires: gas-shielded and self-shielded flux-cored wires. Both of these types have outer sheaths covering the electrode which makes up the flux – a metallic sheath filled with metal powder like alloys and deoxidizers.
Deoxidizers are chemical compounds that can eliminate oxygen in any metal when burned thus it can prevent the contamination of the weld pool from the atmosphere while the alloys serve as the filler. Once the flux-cored electrode touches the base metal, an electric spark is produced which burns out the flux and the electrode and an arc shield is formed.
MIG Welder Without Gas - Difference Between Gas-Shielded and Self-Shielded Flux Wires
Gas-shielded flux-cored wires still need external shield gas like CO2 and Argon to serve as an extra shield in support of the flux and help in melting and solidifying the filler to avoid weld pool runoff. This is why these types of wires are most preferred during overhead or vertical welding or any out-of-position welding where runoff welds are common due to gravity. It is also the best option when fusing thicker metals that need deeper filler penetration.
On the one hand, the self-shielded flux-cored wire is basically the no gas mig welder type wire because it literally doesn’t require any extra gas as it can generate its own shielding gas by burning the flux covering the filler wire. Because of this character, flux-cored welding without gas is better preferred for outdoor welding even in windy conditions.
The good news is, using a mig welder without gas also brings about many advantages. As an ideal choice for outdoor welding applications, this is best used for shipbuilding, structural steel fabrication and also in building bridges. As you noticed, these are all outdoor work activities that require a lot of welding applications. And since gas is not required with self-shielded flux-cored welding, it is also the most chosen applications for general metal fabrication, heavy-equipment manufacturing, pressure vessels and in petrochemical piping.
No Gas MIG Welder Compared to MIG Welder for Solid Wires
If you look closely at a mig welder without gas and a mig welder that uses gas, you can see that the only difference in their physical appearance is the extra gas tank that is required by the mig welder that uses gas. Yet, both use electricity, electrodes, or filler metals and shielding gas to keep out metals from oxidation. They also have the same working principles as in electrode feeding and both produce the arc for shielding.
Opening the units, another recognizable feature that you can see on most modern gasless welders today are their internal spool housing which is generally located on the top just below the hood unlike with the design of the MIGs that use solid wires which are on the internal side of the units. However, you must not be confused about the MIGs because any MIG welder that uses a solid wire electrode can also accommodate flux-cored wires. And as mentioned, the flux on the wire is what makes up the self-shielding on flux-cored welding.
But how do the flux-cored wires can provide more advantages than the solid wire electrodes?
Advantages and Disadvantages of MIG Welding Without Gas
Applying the process of mig welding without gas, flux-cored wire electrodes will allow you to have high deposition rates on your metal work which means you will be able to fill up the joints faster. It will also allow you to weld continuously outdoors even in windy conditions. FCAW is also known as the “all-position welding” and it can deal with even the dirty and rusty metals without much cleaning required. Lastly, flux-cored welding tends to produce clean and stronger welds compared to mig welding that requires solid wire because of its better penetrable capacity.
Yet, there is also a bit of disadvantage to using self-shielding flux-cored wires. Number one is the potential of melting the contact tip if the electrode happens to touch the base metal which can fuse the two together. Second, if in case the gas will not escape from the weld pool and the metal quickly hardens, the weld may result in porous welding as gas will get trapped inside the solidified metal.
Another problem that entails the use of no gas mig welder is its weakness in welding thin metal sheets especially those below the 20 gauge thickness. And we should add that welding aluminum will not work well with flux-cored welding. However, when it comes to fusing harder and thicker metals, flux-core welding can be counted on. So needless to say that MIG welders, gasless or gas-based, are not actually designed for welding thinner metals unlike with the TIG welders.
MIG Welding Using Solid Wires
Essentially, if you want to try using your mig welder without gas, make sure that your wire electrode is flux-cored. So here comes the question again that many people also ask about, can mig welding be possible without using a shielding gas or a flux core? The answer is yes. BUT expect that you will get a very weak joint that will be prone to breakage once it experiences a lot of stress.
Also, there will be lots of holes and pits on the weld because the welding process will undergo a lot of oxidation which means the weld pool will get contaminated by the surrounding atmosphere during welding. So you only have two choices. Either you use gas for solid wires or use flux-cored wire without the need for any gas. You can also opt for the gas-shielded flux-cored wires if you want to use your MIG welder on all position MIG welding.
For the beginners, the no gas mig welder can provide a better advantage because they do not have to deal with the gas flow or need to adjust any gas cylinder just to weld. However, they must be able to identify the codes on the flux-cored wires first to enable them to use these properly for certain types of metal. For example, on the code of E71T-1 which is best for vertical gasless welding position, E stands for electrode, 7 is for tensile strength in PSI multiplied by 10,000, 1 for all position, T for tubular and 1 for usability specification.
Useful Tips About MIG Welding
Here are some tips to help you in setting up your gasless mig welder:
Always choose the right amperage before starting to weld. Amperage settings should be based on the metal thickness of your project and the joint configuration. The wire diameter required and welding position should also be noted and you may find these on the reference chart on your machine.
Choose the right type of flux-cored wire and wire size. For example, the E71T-11 is a general shielded flux-cored wire best for single/multi-pass welding and for welding in any position with a wire size of .030-inch diameter.
Always set the optimal speed of your flux-cored wire but take note of the required gear that the wire requires. This can be included on your set.
Set the polarity. Generally, the DCEN is required for a mig welder without gas.
Check the speed of the spool before starting.
MIG welder without gas can offer you a lot of conveniences. The machines itself are very portable and light. You can carry them anywhere without the need to carry around gas tanks. Also, there’s no need to clean much of your welding project even though it is painted, rusted, or galvanized so this is a convenient choice if your work is on the industrial setting. Another advantage is its favorably for outdoor usage. Even under extreme weather conditions, you can continue working without the worries of contamination with gasless welding.
When it comes to welding penetration and in any position, nothing can also beat the flux-cored welding especially if you use the gas-shielded flux-cored which doubles up the speed in solidifying the weld pool and preventing weld pool runoff. However, flux-cored welding may produce more fumes than the ordinary gas MIG welder that’s why you have to use the right protection for your safety specifically if you weld in a confined space and in an awkward position.
Finally, for those who want to learn more about CO2 mig welding which is the most common type of welding using carbon dioxide and best for fusing thick metals, we will discuss this clearly on the other blog.