Metal Inert Gas or MIG welding has many benefits. However, this welding process is not without its disadvantages. Top of the list is the fact that you have to use a separate shielding gas cylinder. This makes it cumbersome and incapable of being used outside.
The purpose of the gas cylinder is to produce a gas that shields the weld pool from the air. Therefore it is a pretty vital component to have when welding using this technique. Problem is this gas cylinder makes the process cumbersome and incapable of being used outside.
This brings us to a question you have probably asked yourself, is there a way to MIG weld without using an external gas cylinder? Thankfully for you and anyone else who enjoys clean weld finish of MIG welding, there is.
It is possible to use your 220v MIG welder outside without the need for an external gas cylinder. With that in mind, let’s take a close look at how this can be done. Below are some useful tips on how to perform a MIG weld without using gas.
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Use flux-core wires
When welding using a MIG welder, you can either use solid wire electrodes or flux-core wire electrodes. While flux core wire electrodes have a layer of flux material covering them, solid wire electrodes do not.
When using a solid wire electrode, you have to rely on an external gas cylinder to provide shielding gas to protect the weld pool from contaminants and oxygen in the air. Flux-core wires when burnt produce a self-shielding gas. Therefore there is no need to have an external gas tank as the shielding gas is provided by the electrode.
Clean the metal surface
Flux-core electrodes work well on rusted, dirty or painted metal surfaces. Solid wire MIG electrodes, however do not. Thus when using flux-core welding wire, you do not have to clean the metal surface.
However, to get a clean and polished weld finish, cleaning the metal surface is advised. Grinding is one great way of achieving a clean weld surface. Alternatively, you can use a metal brush to get rid of paint and rust.
Removing all foreign materials from the weld surface will significantly improve the look and quality of the weld finish. Also grinding or brushing the surface with a metal brush removes trapped air. Trapped air if not removed, can appear at any point during the weld and interfere with the integrity of the weld finish.
Know the metal you welding
Different metals have different chemical and structural properties. As such, they require different welding techniques. Of the various metals, commonly welded aluminium is the most unique. Welding aluminium without using shielding gas is not recommended.
Steel, however, can easily be welded using flux-core wire. The problem with aluminium is that it has a small layer of aluminium oxide on its surface. This can cause problems when a flux-core wire is used.
Therefore, when you want to MIG weld without using gas, I suggest you stay away from aluminium. Other metals such as steel, stainless steel and copper can be welded using flux-core electrodes with no need for a shielding gas bottle.
Avoid wire feed problems
Using flux-cored wire electrodes can present several challenges for beginners, especially in regards to wire feed. A slow wire feed can result in burnback. This is where the flux-cored electrode melts forming a ball that blocks the contact tip.
Burnback is usually as a result of the welding torch being held too close to the metal being welded. To achieve the best result, the distance between the contact tip and metal should be about 1 1/4 inch.
Use the correct drive roll
Conventional MIG welding uses smooth V-groove drive roll to feed the solid wire. The same drive roll cannot be used to feed flux-core wire. Due to the latter being softer and more tubular it requires a knurled u-groove or V-groove drive roll.
Using the standard smooth V-groove drive roll will result in the flux core being entangled and halting the wire feed process. It is also essential to set the right tension for the drive roll. Tensioning the drive roll goes along way in reducing the chances of the electrode becoming tangled.
To ensure the drive roll is well tensioned increase the tension as you feed it into the palms of your gloved hand.
Flux-core electrodes are known for producing residue that requires after-weld cleanup. Nevertheless, there are ways of eliminating slag. One of the leading causes of slag build-up is incorrect placement of weld bead, especially when welding thicker metal.
Thicker sheets of metal require multiple passes, which can result in slag build-up. To prevent this ensure you have sufficient space to accommodate multiple passes when welding thicker metal. It is also essential to maintain the right angle of travel as well as speed.
Different welding positions require varying angles of welding. Generally speaking you can weld in either horizontal, overhead or flat positions. When welding in either of these positions use an angle of between 15 and 45 degrees. MIG welding can also be performed in a vertical position in which case the angle should be kept to between 5 and 15 degrees.
Also, it is important to maintain a consistent speed when welding.
Prevent excessive penetration
Another common challenge of MIG welding is excess penetration. This is where the weld metal melts into the base metal. Excessive heat input is the number one culprit to blame for this. When you detect this problem lower the voltage range and minimize the wire feed speed. Also, it may be essential to increase travel speed.
With the exception of aluminium which requires argon shielding gas, most metals can be MIG welded without the need for gas. Nonetheless, shielding gas is an essential component of welding that you cannot do without.
As such, MIG welding without gas can only be accomplished using flux-core wires. These wires produce self-shielding gas, thus removing the need for an external gas tank. When using flux-core wire instead of solid wire, there are several things to remember.
For example, the drive rolls used for solid wire are not ideal for flux-core wires. Also, some problems may arise during welding. It is crucial to arm yourself with information on how to counter these challenges.