What’s the Best Gas for MIG Welding – Choosing the Right Gas for the Right Job

Oct 30, 2020

MIG welding uses a hand-held gun that contains a spool-fed wire electrode, along with a gas nozzle that delivers a stream of gas to the weld site. This gas prevents the contact of oxygen, nitrogen, and other environmental gases with the weld bead – which helps ensure consistent, strong results.

Contamination can lead to a low-quality weld on your workpiece, so choosing the right gas is absolutely essential for the best results. But what’s the best gas for MIG welding? Unfortunately, the answer is not that simple.

Different metals require different types of gases for the best results, although in most cases, a 75/25 argon and CO2 mix will let you get good results on most metals. But let’s take a look at some of your options now, and discuss how you can choose the right MIG welding gas for your job.

Argon and Helium (Inert/Noble Gases)

Inert gases like noble gases resist chemical reactions, which means less weld spatter compared to semi-inert gases like carbon dioxide. There are six noble gases, but for the purposes of MIG welding, only argon and helium are typically used. Pure mixtures of argon/helium are usually only used for nonferrous metals like copper and aluminum.

Both gases are appropriate for MIG welding, but argon is used more frequently. These two gases can be mixed together to take advantage of their beneficial properties, depending on the weld.

Argon, for example, usually provides a stable arc but a wider and more shallow weld penetration. Helium, on the other hand, is pricier but burns hotter for a deeper weld. Mixing these gases helps balance these characteristics, and produce a consistent weld.

Note also that both of these gases are expensive compared to others like carbon dioxide, so they’re often mixed with carbon dioxide to save some money, but still provide excellent welding results.

Carbon dioxide may make up to 10-25% of the volume of the gas, depending on the situation. A 75/25 argon and CO2 blend is typically considered to be the best overall option for MIG welding, so that’s our top recommendation at Vern Lewis Welding Supply.

A “tri-mix” of helium, argon, and CO2 is also sometimes used. This mix of gas is ideal for stainless steel welding, as it ensures a steady, strong, and deep weld.

Carbon Dioxide

Carbon dioxide is a “semi-inert” gas that is relatively resistant to chemical change, but to a lower extent than inert gasses like argon and helium.

It’s used frequently in MIG welding, often on its own (100% CO2), or as a small percentage of a helium or argon gas mix. A 75/25 MIG Argon and CO2 mix is the most popular gas for MIG welding sales, making up more than 90% of the gas we sell at Vern Lewis Welding Supply.

CO2 is much cheaper than inert gas, and it allows the bond to penetrate very deeply into the metal when welding. However, it has a much harsher arc that can be more difficult to control, and its semi-inert nature leads to more weld spattering, so the weld requires more cleanup compared to a noble gas.

Carbon dioxide is particularly useful when working with ferrous metals like mild steel. 100% CO2 is sometimes used for this purpose, but this is a more “old school” approach used for specialty wires – for general MIG welding purposes, 72/25 Argon/CO2 or a tri-mix of CO2, argon, and helium is much more common.

What’s the Best Gas for MIG Welding Different Metals?

If you want a “one-size-fits-all” option, a MIG welding shielding gas with a 75/25 mix of argon and CO2 is likely going to be your best bet. We carry a high-quality 75/25 argon and CO2 mix at Vern Lewis Welding Supply, which is an ideal, cost-effective option that can be used to weld most metals, including mild steel and nonferrous metals. If you have any questions or need assistance when choosing the best gas for MIG welding, contact us today.

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