MIG Gas Settings: How to Set Gas on MIG Welder

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MIG or Metal Inert Gas has been used for nearly 80 years and is a favorite among new welders. A great feature of MIG welding is that it can melt different sized metals together, though it is mainly used for thicker pieces. 

Setting the gas on a MIG welding set can be simple, requiring limited background knowledge on welding. Today, MIG welding will be explained, and you will also learn how to set shielded gas used for welding. The importance of safety and some of the best shield gases to use will also be discussed.

This article will detail how to set the gas on a MIG welding set, and what are the different types of shield gases to use. 

Setting The Gas On Your MIG Welder

MIG gas rates tend to be very low compared to other forms of welding, The gas flow rate from the shield gas is measured in CFM or Cubic Feet Per Minute. Different areas or different conditions can affect CFM numbers.

The typical gas pressure when welding with MIG tends to be around 3 to 8 psi, this is very low compared to other types of welding. 

Shielding Gas

The shielding gas provides the gas needed for MIG welding. When starting, it is important to make sure the gas bottle is properly installed into the holder. It is also necessary to check the hose and gas regulator to make sure there is no damage and replace any broken or damaged parts.

When installing the regulator and hose onto the shield gas, it is important to ensure that the seals are tight and not leaking gases. Leaking gas can result in asphyxiation caused by a lack of oxygen, which can be deadly.

Using MIG

There are a few things you should do before and after turning on a MIG welder:

  • Check the wire before use.
  • Turn on the MIG welder.
  • Check the gas values. Ideal numbers are between 25 and 30 cubic foot-hours.
  • Trim the wire inside the gun tip, making sure it is not too long.

The wire inside of the MIG is not protected from rust or dust, so checking the wire before each use is vital. It is important to use a metal brush or a grinder to clean the wire and the inside of the MIG tip each time.

Ideal Presure Numners

Gas flow is primarily measured in cubic feet per hour, how much gas is being released each hour of use. To figure out how much pressure and the flow rate is needed for the shield gas, you need the shroud diameter which is the tip of the MIG welding handle. This chart can help figure out what flow rate you need based on the size (The Welders).

Flow Rates6791012

When first turning of the MIG machine and setting up the shield gas, the ideal number is 25 and 30 cubic foot-hours. Many regulators have a present already built into the shield gas, which releases the gas pressure, But the flow rate can be controlled. 

Adjusting Pressure 

The last step is to adjust the pressure as needed. If you are in a windy environment, higher gas pressure is needed, but the normal reading should be between 25 and 30 cubic foot-hours. Always keep the ideal numbers in mind.

When connecting the gas to the MIG, release the glass slowly until you feel resistance, then start to open the valve until it reaches the desired amount. Be sure to open the valve slowly to avoid any errors.

What is Shielding Gas?

Shielding gas protects the melting metals from being exposed to outside gases by using a steady stream of a different type of gas. There are many types of shielding gas that can be purchased, such as:

  • Carbon Dioxide
  • Argon
  • Oxygen
  • Helium

Each of these gases has its pros and cons. Keep in mind that there is no perfect gas to be used when MIG welding. Factors such as price, what type of metal, and what the project is meant for will need to be considered when trying any of these gases.

Cubic Feet Per Hour

CFM is used to pressure the rate of the shielding gas, this is different than the flow rate which measures how much gas comes out. For most welding, you need 25 to 30 cubic feet per hour, but with thicker pieces of metal more gas is needed. 

This graph shows the normal CFM flow chart for MIG welding: (Flow Chart)

MIG Gun Diameter Minimum FlowTypical FlowMaximum Flow
⅜ Inches15 CFH18-22 CFH 30 CFH
½ Inches 18 CFH22-27 CFH40 CFH
⅝ Inches 22 CFH30-35 CFH55 CFH
¾ Inches30 CFH30-40 CFH65 CFH

The average-sized MIG welding gun diameter is ⅝ inches, most welders would be using have a minimum flow of 22 CFH to a maximum flow of 55 CFH. 

The flow rate can drastically affect that welding, with a flow rate that’s too fast outside air can be pulled in resulting in contamination. It can take a lot of experience to be able to know that the flow rate is needed (CFM).

Different Sheild Gas 

The different metals that can be welding with MIG do not affect the shield gas but rather would affect the flow rate. This is due to the different thicknesses of metals and how long it takes to heat and melt the metal. 

Gases like Helium are great options for welding metals at very high heat, such as copper, and aluminum. The different types of gases can affect how the metal melts and how it reacts. 

While Argon is very stable, making it one of the most popular options, it can even help clean out the MIG welding gun while using it. Both Argon and Helium can be mixed together to help reach an even higher melting point.

For metals like carbon steel the best shield gas is a 75% argon and 25% carbon dioxide mixture, it has a high temperature. Another key part of this gas is that it produces minimum splatter, which can be dangerous if it hits the skin (MIG Welding).


What Is The Best Shielding Gas for MIG? 

Multiple gases can be used for shielding gas, with Argon being the best gas to use. This is because it gives a nice finish and is composed of 25% Carbon and 75% Argon. However, this gas is not one of the cheaper options. Argon is a particularly great option for people working with thinner metals and those wanting a nice finish. 

Carbon Dioxide is another commonly used gas and can be used without an inert gas, which is great for people trying to save money. Using 100% Carbon will not give a clean finish, but it is available in most stores, making it one of the easiest gases to find and use.

Different Pressure Per Gas

Each type of shield gas will perform differently based on what type of metal is being welded. For a pure 100 percent argon shield gas, a flow rate of 20 to 30 cubic feet per hour is recommended when welding aluminum (Shield Gas).

Shield Gases like oxygen have much higher pressure and can lead to a huge safety threat due to it, with pressures near 3000 psi (Gases – Shield Gas). Yet different manufactures of shield gas set the pressure amounts to different levels, due to this the welders need to be aware when setting the gas levels.


MIG welding is a great option for beginners and a good introduction to welding. It is also a much cheaper option than TIG welding. Shield gas can come in all different price points, and it is interesting that you can try all types of gases to see how they affect the metals.


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