Shielding gases for MIG welding produces faster and cleaner welds. Unlike stick welding, we do not have to replace electrodes in MIG welding. The shielding gas increases efficiency and helps you to clean up the splatter easily. But this doesn’t change the fact that shielding gas plays a greater role in welding than just clean welds.
Welders use different MIG welding gases with specific properties to increase efficiency in the welding process. Choosing the right MIG shielding gas saves your time and money while improving your weld quality.
You must consider several factors, such as the transfer method, the cost, the cleanup time, and the material while choosing the right type of gas.
What gas is used for MIG welding?
As the name suggests, Metal Inert Gas is used for MIG welding. It is a type of MIG shielding gas that prevents unwanted contaminants in the air from disturbing the welding surface. Oxygen or nitrogen enters your welding area and contaminates your weld, hence, comprising its quality.
Shielding gas for MIG welding
All shielding gases are composed of semi-inert or inert gas. However, we use them in small percentages. It does not turn the process into MIG welding, rather, it turns it into a GMAW welding process.
Whether you wish to weld non-ferrous or ferrous metals, you will have to choose from a range of mixes to pure forms of both gases. If your pocket allows, you can buy an expensive gaseous mixture to weld stainless steel.
Shielding gases, if not selected carefully, can cause problems such as spattering, excessive fumes, burnouts, and bead patterns.
That being said, novice welders find it a little difficult to select the right shielding gas when there are so many options available on the market.
This is where Welding Rage shines. Keep reading and we’ll help you select the right shielding gas for your best welding equipment.
Helium and Argon- Inert gases for MIG welding
An inert or noble gas is a substantial shielding gas in the welding process. It is resistant to chemical reactions under various circumstances. Helium gas and argon gas for MIG welding are two common noble gases that we use in both, TIG and MIG welding.
While we use helium for TIG welding, experts suggest using Argon for MIG welding. We mix the gas with helium or use it as a stand-alone shielding gas.
Helium is more expensive because it burns hotter in comparison to Argon. Whereas, argon achieves a stable arc and wider but shallow weld penetration.
As both inert gases are expensive, professional experts mix them with other gases. Moreover, they have limitations and can only weld non-ferrous metals like copper and aluminum.
Unlike semi-inert gases, they produce less spatter as they resist the change to chemical reactions. While using helium, you have to be extra considerate and cautious as it burns hot and can cause overheating and burnouts.
Non-inert and semi-inert gas for MIG welding
Semi-inert gases are also resistant to chemical reactions in the MIG welding process but to a lesser extent in comparison to inert gases. Most welders, hobbyists, and enthusiasts use carbon dioxide (a semi-inert gas) in the MIG welding process. They either mix it with an inert gas in a small percentile or use it as a stand-alone welding gas.
The benefit of using carbon dioxide is that it’s cheaper and allows you to make deeply-penetrated welds. However, it is a harsh gas and results in more spattering as compared to noble gases. You will require more time to clean up.
Oxygen is a non-inter gas that aids the MIG welding process. We use it in a small percentage with other gases to increase the depth of the welds. We also use it when the welding object is made of thicker metal, like stainless steel.
Although oxygen is responsible for the rust and oxidation layer on the metal surface, professionals still use it in small quantities to stabilize the arc. Moreover, it is a popular gas among welders due to its cost.
Argon- Carbon Dioxide or C25- What is the advantage of using mixed gas for MIG welding?
Each of the inert, semi-inert, and non-inert gases that we have discussed has its advantages, disadvantages, and specific properties. We mix most of them, such as argon and carbon dioxide for various welding purposes.
The most common MIG welding gas mix is the combination of 25% carbon dioxide and 75% argon. This mixture is also known as C25. On the other hand, the mixtures of 10% carbon dioxide and 90% argon, 20% carbon dioxide, and 80% argon are commonly used for MIG welding too.
You can use argon for MIG welding. However, it has certain disadvantages and limitations. Thereby, experts recommend using it with a MIG welding gas mix.
Why is C25 used for most welding applications?
While the mixture of C25 is expensive than 100% carbon dioxide, it is cheaper than 100% argon. The cost of the shielding gas mainly depends on the content of noble gas. The higher the concentration, the higher the price.
The welding profile of the argon-carbon dioxide mix is narrow, results in quick clean-up and less splatter. That is why it is the go-to shielding gas mixture for most welding applications.
While C25 is considered an optimal shielding gas, it is the welding transfer method that will determine the type of gas you should use.
If you are up for short-circuit or short-arc welding, shielding gas with 25% carbon dioxide is the best option. However, you use 1005 noble shielding gas (argon) for strong spray arc welding and globular welding transfer. But again, the catch here is the cost of the gas.
What is the best gas used for welding mild steel?
We use 100% pure carbon dioxide or C25 for welding mild steel. Low-carbon steel is affordable and easier to weld as compared to high-carbon steel. The lower content of carbon with other metal alloys makes it prone to oxidation and rust.
100% pure CO2 is often used by hobbyist and beginner welders. This is because carbon dioxide is easily available in its pure form and also inexpensive.
One can also use the mixture of argon and CO2 to get clean welds with less spatter and fumes. Here is a quick overview of using both these options.
| Gas Used | Output |
| 100% CO2 | Deeper penetration but more spatter, fumes, and rough welds. |
| 75% Argon & 25% CO2 | Ideal bead appearance, less spatter, and prevent burn-through. |
Why are inert gases not suitable for welding steel?
The experts suggest that the noble shielding gases, Helium, and argon are not suitable for welding steel because we get inconsistent, ugly, and undercut welds. The job of a professional is to avoid undercut; a groove in the weld bead due to high voltage or fluctuating speed.
The hobbyists use argon or helium with 5% of oxygen for numerous applications in the automotive industry. With this mixture, we can also weld stainless steel and carbon steel. However, rust and oxidations occurring risks rise when in contact with low-carbon steel.
What gas is suitable for welding stainless steel? – The tri-mix
We use a mixture of carbon dioxide, argon, and helium to weld stainless steel. In some industrial applications, the welders use the trio of oxygen, argon, and helium. 2.5% carbon dioxide, 7.5% argon and 90% helium are an example of a tri-mix to weld stainless steel.
While we use oxygen to stabilize the arc and penetrate through thicker metals, helium provides heat. However, we have to provide high voltage to added levels of helium and carbon dioxide to stabilize the arc.
That’s why many welders switch to a more affordable option; 2% carbon dioxide and 98% argon.
Is the same gas used for TIG and MIG welding?
Tungsten inter-gas welding or TIG welding is another type of process to join two metals. This welding process relies on helium, argon, or the mixture of the following gases.
Although we can TIG weld using oxygen and carbon dioxide, experts do not recommend it. Using carbon dioxide or oxygen will lead to overheating and flare-ups.
Besides using argon gas for TIG welding, you can use the same gas for MIG-weld aluminum. However, it should be thin and less than ½ inch in thickness. So, if your work includes a lot of MIG and TIG welding, one cylinder of pure argon could cover a wide range of applications.
Gas flow rate for MIG welding
The flow rate of gas is different from pressure and we measure it in cubic feet per hour rather than Psi. Generally, the flow rate of the gas has to be high enough to weld but it develops other risks. For example, the hose sucks air into the weld.
If you don’t set the right gas flow, you MIG welder may start sputtering.
You can set the flow rate to as low as 15 CPH in an enclosed area. However, you have to keep the rate at 50 CFH if you need to draft a deeper weld. The flow rate of the gas also depends on the nozzle’s diameter. So, do not forget to check the recommendations of the manufacturer before operating your welding equipment.
The other factor that affects the flow rate of the gas are:
- Welding speed
- Welding surface
Gas pressure for MIG welding
The gas pressure in the regulator is set between the range of 25 PSI to 80 PSI. We reduce the pressure of the welding gun hose through the orifice or the needle valve. The factory preset range of pressure for the hose is between 3 to 8 PSI. The gas pressure mainly depends on the nozzle of the gun.
Frequently Asked Questions – FAQs
Conclusion
The shielding gas, its pressure, and its flow rate are key to avoiding overheating and achieving a consistent beat pattern. Make the most of your gas flow rate and consider the manufacturer’s recommendations and the material you’re trying to weld.
Jaxon is an integral part of Welding Rage team. He’s a writer and working closely to the welding industry for years. Jaxon is helping us shortlisting the best MIG welders on the market with his welder friends.
