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The cool thing about MIG machines is that they can run a large variety of wire types.
Hardwire is generally best for fabrication. It doesn’t produce any slag, so you can fabricate quicker with less clean up afterwards. Hardwire is the most common type of wire, and is usually what people are referring to when they mention MIG welding.
Flux core comes in 2 main wire types. Single shielded flux core requires no external gas. Similar to a stick welding electrode, this wire produces its own shielding atmosphere without the need for a gas cylinder. This makes it great for smaller machines and home setups. It also cuts down on costs because you don’t have to buy a gas cylinder or get refills.
Dual shield flux core uses both the flux from the wire and an external gas to achieve a high penetration weld. This is generally best for large fabrication jobs and ironworking. Welders who do a lot of beam work prefer a dual shield setup. The welds are very strong and it is a faster process than stick welding. You can lay down large beads without having to replace your electrode.
You can also run stainless steel wire through a MIG machine. This wire is more expensive and a bit harder to use because of its sluggish puddle. It is harder to manipulate the puddle and new welders can get frustrated with stainless MIG.
Aluminum MIG can be performed with the use of a “spool gun”. This is a smaller machine that is specifically designed to run aluminum wire.
These handy machines hold small spools of aluminum wire, and they work really well for aluminum fabrication. However, this tends to be more expensive since you can’t just load a roll of aluminum wire into your machine. The extra accessories that are required can get pricey.
This article will cover our favorite MIG wires that are currently on the market.
INEFIL ER70S-6 Hardwire MIG .030″ (10 lb Spool)
This is a great hardwire that is perfect for most steel fabrication. The 10 pound spool lasts for quite a while (for the average welder). If you want to get into fabrication, this is a great starter spool.
Keep in mind that this will require an external shielding gas. Make sure that your MIG machine has a gas port – some lower end MIG machines don’t have a gas port, which means that you can only run single shielded flux wire. A 75%/25% (argon/C02) mix is the most popular gas choice for hardwire.
The ER70 wire is extremely common for other types of welding as well. TIG filler wire comes in ER70 as well, which can perform welds on mild steel. This wire is extremely strong and has a strength of 70,000 lbs per square inch of weld (psi).
This type of ER70 hardwire can be found in welding shops across the world.
Although it is great for fabrication, it doesn’t penetrate as well as a flux core weld. It is generally good practice to remove your mill scale before welding with this wire. The model listed above is .030″, but it is available in other diameters as well.
Depending on the size of steel you’ll be welding, you may want a smaller or larger diameter wire.
If you have recently purchased a MIG machine and just want to get welding asap, this wire is worth a look.
PGN Gasless Flux Core Wire .030″ (10 lb Spool)
This is the gasless type of wire that we listed in the intro. For welders that don’t want to deal with using a cylinder and getting gas refills, this is a good option.
Since the flux produces its own atmosphere to protect the puddle, you can get high penetration welds with this wire. Keep in mind that it is messier since there is a flux coating after you finish a weld. A wire brush or wire wheel will get rid of the flux, and you’ll be left with a nice, shiny weld.
This wire is great for most mild steel applications. If your machine is capable of higher voltages, you can burn this wire into some really thick steel.
Some welders think that since there is no gas used, flux core is weaker. Although it isn’t as strong as a dual shield flux setup, this gasless wire can produce some extremely strong welds.
We like to think of this as the MIG alternative to stick welding. However, it is a faster process than stick welding since you don’t have to keep replacing your electrodes. The 10 pound spool will last the average hobbyist quite awhile.
ESAB Dual Shield Flux Core Wire .045″ (33 lb Spool)
This is the big dog wire. You’ll see this wire in structural welding shops, as well as on large construction jobs. The penetration is unmatched, and this spool can burn into basically any thickness of steel. With this being said, you’ll need a capable machine that can run high voltages.
This wire is often burned at over 25 volts, and most budget MIG machines won’t be able to handle this.
For welders that do garage projects or weld around the house, this probably isn’t the best pick. It tends to be a wire that is used more in professional settings.
You’ll want to make sure you have a leather jacket and complete PPE when using this wire. If you aren’t completely covered, it can cause serious burns – especially with overhead (4G) welding.
The 33 pound spool is one of the larger spool sizes available, and will last for quite some time. If you are an independent welder that takes on larger structural jobs, you’ll probably want a dual shield setup on your rig. Stick welding works fine for structural projects, but dual shield gets the job done faster.
Dual shield flux core runs well with 100% C02 gas.
This wire is also used on common welding tests like a 3G plate test. If you are trying to test in for a shop position, knowing how to run this wire is a huge plus. Welding schools will usually run tests with this wire as well. It burns hotter and faster than any other wire, so getting some dual shield practice is a must.
Starting out with a 1G plate test (flat) is good practice for beginners. You can then work on 2G (horizontal) and 3G (vertical) tests. Some companies will require a 4G (overhead) test with dual shield wire. Overhead is generally the hardest plate test for most folks.
WeldingCity ER316L Stainless MIG Wire .030″ (2 lb Spool)
If you are fabricating stainless pieces and TIG is taking you forever, MIG might be worth trying out.
Stainless MIG achieves high penetration welds in a quick manner, and is great for burning welds into thicker stainless materials.
This spool is the 316 version. 316 stainless has high corrosion resistance because it contains molybdenum. It is often used for products that will be exposed to moisture. This makes it a common choice for marine applications and food processing operations.
308 spools are also available. 308 stainless has less corrosion resistance, but it is still very strong and used in many products. It is more of a mid range quality.
309 wire is used to weld stainless steel to mild steel. This isn’t ideal since it is prone to cracking, but it is possible.
This 316 wire from WeldingCity burns really nicely. We used it on a few projects and it seemed less sluggish than other stainless wires we have used. The tri-mix is our favorite gas when running stainless MIG. It consists of 90% helium/7.5% argon/ and 2.5% C02. This is one of the more expensive gas mixtures, so definitely make sure to conserve it when possible.
This wire is also quite a bit more expensive than regular hardwire. Stainless steel is expensive in general, so it makes sense that the filler wire will also cost more. This 2 lb spool is definitely pricey, but it can produce some amazing welds.
Hobart Aluminum MIG Wire .030″ (1 lb Spool)
If you have a spool gun MIG welding setup, then you’re probably familiar with these little 1 pound spools of aluminum wire.
This model from Hobart gets the job done and produces some really clean welds. Although these 1 pound spools don’t last long, they are a great choice if you are doing larger aluminum projects.
When TIG welding aluminum seems too grueling, MIG is a great option to turn to. Hobarts filler metals aren’t the priciest, but they can produce awesome welds while remaining budget friendly.
This aluminum filler metal is also very corrosion resistant (even for saltwater applications).
As you can tell, there are many types of MIG wires available. This is what makes MIG welding a truly versatile process. While most welders tend to stick with hardwire, playing around with the other filler metals can be super fun and productive.
Since MIG welding has so many different options, this makes it a great process for beginners that want to work with different types of wire processes. It is easier to learn than TIG or stick welding, and many beginners can lay a good bead once they get a bit of practice.
Gaining experience running all of these wire types will leave you a more well rounded welder. From an employers perspective, having a welder that can do it all is really a bonus.
If you are doing a welding test for a job position, having practice with these types of wire will set you up for a better rate of success.
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