For most welders, especially beginners, it is often challenging to set the right parameters on their MIG welder. You’re probably in the same predicament, so we’ll explain the basics of shielding gas settings and how they can be adjusted for optimal performance.
Aside from selecting good MIG equipment, ensuring proper MIG gas settings is crucial to the weld quality.
The primary aim of the shielding gas is to protect the welded area from atmospheric contaminants including, Nitrogen, Oxygen, and Hydrogen. These contaminants can create a number of problems on the welding pool, such as porosity, excessive spatter, and inconsistent bead appearance.
Even if you select the right welding equipment, all your efforts will go to waste if you don’t get it right with the shielding gas. In addition, different MIG shielding gases play a big part in either improving or impeding the quality of finished welds.
Having said that, here are a few basic tips to help you set the correct MIG welding gas parameters;
i. Gas selection
The recommended shielding gases for MIG welding are Argon and Carbon dioxide. For most applications, you can use a combination of 75% argon and 25% carbon dioxide. This blend produces the best bead appearance with the least spatter.
You can also opt to go with 100% carbon dioxide to provide deep penetration, especially when welding thick metals. However, these applications are characterized by increased splattering than when CO2 is mixed with Ar.
When choosing your shielding gas, you may also want to consider the cost of the gas and the finished weld expectations.
ii. Securing the gas tank to the welder
The next step after you’ve selected your shielding gas is ensuring that the gas tank is firmly attached to the welder. A typical MIG comes with a holder where the tank can rest and a chain to keep it in place. However, different welders may have varying designs for securing the gas bottle.
iii. Inspect all connections
Once the tank is in place, you may want to inspect all connections and hoses for any signs of damages or cracks. Ensure to repair or replace any damaged parts to keep gas leaks at bay.
At this stage, you can now install your gas regulator into the outlet valve of the gas tank and lock it in place with a wrench. You may also want to ensure that the tank is full and the connections are tight.
Gas flow rate settings
Once you’re sure that everything is in place, you can proceed with the gas settings. To produce the best welding results, you’ll need to set your gas flow rate properly. The standard unit for shielding gas flow rate is denoted by cubic feet per minute (CFM).
The settings may vary depending on the materials being welded and welding conditions. However, for most applications, the rate can be anywhere between 20 and 30 cubic feet per minute. As such, ensure to follow the user manual for the specific requirements for the job at hand. Most manufacturers provide MIG welding gas flow rate charts to get you started.
For best results, ensure that the flow rate is sufficient enough. If the flow rate is too low, it can lead to oxidation or porosity in the final result. Too much gas, on the other hand, generates turbulence on the weld area, which can compromise the weld quality.
It is important to note that the flow rate will be mainly be guided by the thickness of your materials. The thicker the materials, the higher the flow rate, whereas a lower flow rate applies to thin materials. However, you may be required to increase or decrease the flow rate as the conditions change.
For instance, you may need to supply more shielding gas when welding out in the wind. However, it is not still recommended to perform MIG welds out in the wind.
Other than the gas regulator, the MIG consumables i.e. the contact tip, nozzle, and diffuser, plays an important role in ensuring a sufficient gas flow.
For instance, if the nozzle is too small, the flow rate is going to decrease. This will in turn reduce reducing the amount of shielding gas reaching the weld pool.
On the other hand, if you are using a clogged diffuser, there is a high likelihood of blocking the gas from getting to the weld area leading to contamination or excessive spatter.
As such, when choosing your consumables, make sure that the sizing is correct to ensure sufficient gas flow and minimize spatter build-up.
The Bottom Line
Setting the correct gas flow rate is as important as selecting the right equipment for MIG welding.