When most people think of MIG welding, they think of hardwire – a mild steel process in which ER-70 wire is used to weld regular steel. What newbies may not know is that there are so many wire types available that can tackle vastly different projects.
If you have a MIG machine, there are several types of wire that will work with your setup. This article will cover all the common wire types, and the benefits of each wire. Although they all run through the same MIG nozzle, they behave very differently from each other during the welding process.
Keep in mind that every wire type also comes in different diameters. The most common diameters are .025″, .030″ and .035″ (although .040″ and .045″ are not uncommon)
Hard Wire MIG
This is the most common wire on the market; most fabrication shops will have a majority of their MIG machines set up with hardwire. It is relatively affordable, and beginners will have an easier time with learning hardwire than they will with other wire types.
As mentioned in our MIG welding overview article, hardwire tends to run best with a 75/25 mix of argon and Co2, respectively.
There are so many bead patterns and techniques that you can use to achieve the same amount of penetration with hardwire. Different welders/fabricators will have beads that look very dissimilar to one another. Some folks will push their puddle, while others prefer to pull.
There are multiple types of hard wire. They are all meant for welding mild steel, but they vary in terms of how “hard” they actually are. Some wire has properties that make it harder than the steel itself, while others are a bit softer.
We tend to stick with ER70S-6, but beginners shouldn’t worry about these details when they’re first starting. It mainly comes down to the elements that are put into the wire – ER70S-6 has higher levels of silicone and manganese, while ER70S-2 has more deoxidizers like zirconium and titanium.
Due to the fact that there’s no slag involved, hardwire is one of the fastest processes for fabricators who want to increase efficiency. You can weld in literally any position with this wire type; Uphill, downhill, flat, horizontal, overhead, diagonal etc…
Downsides Of Hard Wire MIG
There aren’t too many downsides to hardwire, besides the fact that it doesn’t penetrate as well as other processes. Processes like stick welding and flux core welding have more of a “digging” arc characteristic. This penetrates the steel more and leaves you with a very satisfactory weld.
Welding on a low voltage setting with hardwire can lead to cracked welds later on. We always recommend cleaning your mill scale prior to welding with hardwire. This will ensure that you are welding straight into the base material every time.
Overall, hardwire is a great process, and we recommend all beginners start with it before moving onto other wire types.
Gasless Flux Core Wire
This is a MIG process in which the flux is built into the wire itself, so no external shielding gas is required. Think of gasless flux core as the MIG equivalent to stick welding; no gas cylinders involved, just turn your machine on and start welding.
Although this is a messy process due to the large amount of slag and spatter, it is actually quite strong and durable. Gasless flux core welds can produce some beautiful beads, and beginners can purchase a machine and a small spool of flux wire for a reasonable price.
We recommend this process for any hobbyist that likes building personal projects, but isn’t concerned with having top notch welds on every joint. It is convenient and extremely user friendly.
Make sure to invest in a standard wire brush or a cup brush attachment for your angle grinder. After each flux core weld, the slag must be cleaned off before you can see what your bead looks like.
Dual Shield Flux Core Wire
We like to think of dual shield flux core as regular flux core MIG on steroids. You use very similar wire to gasless flux core, but it is designed to be used with a shielding gas at the same time. A 75/25 argon/Co2 mix is often used during this process (the same as hardwire MIG).
This dual shield process achieves ultimate penetration with 2 shielding properties, and is the choice of many structural welders worldwide. The beads are much wider than most stick welds, and the characteristics of the dual shield flux core arc can penetrate through rust and heavy mill scale.
For structural fabrication, shop workers need to be able to make quick work of I-beam projects, and stick welding can be a real hassle. To avoid rod stubs all over the floor and constant replacement of rods, using dual shield instead can skyrocket the productivity of beam fabrication.
Often times, dual shield is run with larger diameter wires than usual MIG processes. Sizes like .040″ and .045″ are quite common with this process. Using these wire sizes can produce very wide, flat beads in a single pass.
Dual shield flux core requires lots of power. Voltage settings up to 30 are not uncommon, and power outlets up to 480v are often called for.
For the hobby welder, smaller diameter dual shield wires can be very productive in a garage or workshop setting. If you are fabricating on a strict timeframe and must maximize the working hours in a day, dual shield is really worth looking into.
Stainless Steel Wire
When people think of stainless steel welding applications, TIG is often the first process that comes to mind; rainbow colors, perfect dimes, instagram photos… Although stainless welds are often performed with TIG processes, stainless MIG has become increasingly popular over the years as well.
Stainless MIG runs relatively similar to hardwire, but the bead is more “sluggish”. Newbies may find it harder to push and manipulate the puddle with stainless MIG. The puddle heats up extremely fast, and if you don’t maintain a faster travel speed, then you can burn through your material.
Stainless steel MIG wire is also quite expensive. It isn’t really a product that you want to waste or mess around with. If you’re welding stainless with MIG, you should maximize your profits (this often means charging the customer more money per hour).
As mentioned in our MIG gases article, a tri-mix is the preferred gas for stainless MIG. 90% helium/7.5% argon/2.5% Co2 is our personal favorite, but it is one of the more expensive gas refills on the market.
Welding stainless with a MIG machine is very enjoyable for the most part, but quite costly: New welders may want to hold off until they have become sufficient with hardwire and flux core.
Aluminum MIG Wire
Welding with aluminum MIG requires a different skill set and a different set of equipment. Due to aluminum wire being so soft, it is nearly impossible to run it through a normal MIG cable.
Straight argon gas works great for the aluminum MIG process, although you can introduce small amounts of helium for a better puddle.
Manufacturers realized over time that aluminum MIG is best made on small, one pound spools. Once a welder purchases a “spool machine” paired with an appropriate MIG machine, they can load the small spool of aluminum wire and begin welding.
The reason for this setup is that the aluminum wire only travels about 10-12 inches before it makes contact with the aluminum work piece. This means that it has much less chance of jamming on the way to your project. If you ran aluminum wire through a normal 4-5 foot MIG cable, it would almost certainly jam. When aluminum wire jams, it becomes super crinkled and can be very hard to fix.
Downsides Of Aluminum MIG
This aluminum wire also behaves very differently than the other wires listed above. It is a very temperamental arc, and fast travel speeds are often required.
The penetration of aluminum MIG wire isn’t as consistent as a nice, wet TIG arc – but with practice you can produce some very strong welds with this process. Using a stainless steel wire brush to clean your aluminum prior to welding is always a great bet. If your aluminum is dirty when you begin welding, the chances of cracks and breaks becomes a lot higher.
If you know how to run aluminum TIG and aluminum MIG processes, you can make some great cash. Aluminum trailers break all the time, and there’s always potential customers looking for an aluminum welder that can solve their problem.
Although it may seem overwhelming to have so many wire choices, it is actually a great thing because it gives you tons of options for projects. Knowing how to run MIG with all of the wires listed above will put your skills and knowledge beyond most welders out there. It can also mean you’ll have the option to charge a high hourly rate for your welds if you choose to.
When a client hires you, they’re not just looking for a “welder”. They are looking for a problem solver that can provide metal solutions based on their needs. When you think of your skill set this way, it will allow you to provide awesome solutions to clients problems. Jobs will often involve a lot more than just welding, and prep work is often a majority of the hours spent on a project.
So whether you’re bidding on jobs and using your MIG welder to make money, or you’re just a hobbyist – being well versed with all wire types is extremely beneficial
Featured image credit : Wikimedia Commons