How Does a MIG Welder Work: Things to Consider

MIG welders are one of the most popular types of welding machine for their easy operation and their ability to work on a variety of metals including aluminum, stainless steel, and mild steel.  They produce long, continuous welds much faster and simpler than traditional welding methods. In fact, because of their ease of use, MIG welding machines are the most recommended learning tools for beginning welders. Starting with one of these machines will allow you to hone your welding skills with relative ease.

What is an MIG Welding Machine?

MIG stands for Metal Inert Gas, also sometimes referred to as Gas Metal Arc Welding (GMAW) machines. This process of welding was developed in the 1940s as a way to weld aluminum and other non-ferrous materials. A non-ferrous metal is a metal that doesn’t contain iron. MIG welders come with a feeding wire allowing you to weld materials with varying degrees of thickness. Many welders consider MIG machines to be the best tool for both home and industrial welding.

MIG welding is an automatic or semi-automatic process in which a wire, which is connected to a direct current source, is continuously passed through a welding gun and acts as an electrode to join two pieces of metal together. A flow of an inert gas like argon, or a semi-inert gas like carbon dioxide, is passed through the welding gun at the same time as the wire and acts as a shield, keeping contaminants away from the weld zone.

The main advantage of MIG welding is that it allows metal to be welded much quicker than traditional stick welding techniques. In the early days of this welding method, the high cost of the gas made the process too expensive for welding steel. Over the years, however, the process has evolved and semi-inert gases like carbon dioxide can now be used. This means that these days MIG welding can sometimes be cost-effective for welding steel.

To perform an up-to-standard weld, you’ll need to choose the right machine for the job. The quality of your work greatly depends on which welding machine you decide to purchase, and there are quite a bit of welders on the market to pick from, so it pays to do the proper research before making your final purchase.

Factors to Consider When Choosing a MIG Welder

One welding machine can’t do it all. There are many different styles and models of welders on the market, each suited to different kinds of welding jobs. So how does one choose the right MIG welder for the job? You want to choose a welder that can handle the workload, but you also don’t want to put yourself in debt by spending more money than necessary on an overpowered machine. You can determine what kind of welding machine you’ll need for your specific situation by analyzing several determining factors:

Type of Metal

When purchasing an MIG welder, it’s important to know what kind of metals you’ll be working with. MIG welders are used for non-ferrous metals and low-alloy steels, which are created with precise chemical compositions and provide better mechanical properties than many conventional mild or carbon steels. Typically, these additional alloys only make up about 1 to 5 percent of the steel’s content. Alloys are added based on their ability to provide very specific attributes.

Some examples of these alloy attributes would be molybdenum for improving the strength of the material and nickel for added durability. Adding chromium to the steel increases hardness, temperature strength, and protects against corrosion. Manganese and silicon provide deoxidizing capabilities. Even with these additions, low-alloy steel is relatively simple to weld.

Material Thickness

Before choosing an MIG welder, t’s important to think about how thick or thin the metal is that you’ll be working on. Your welder will need to have the proper amount of amperage or heat necessary for your particular project. If you’re working with thin metals you can go with a light-duty welder, as less heat will be needed to weld them. For thicker materials, a heavy-duty gun will be required to provide long bursts of high heat. Use caution when choosing the right machine, as using a high-powered welder on a thin material is an easy way to mess up the weld and burn through the metal.

Type of Gas

MIG welders use several different gas types. The two most popular are argon and carbon dioxide, or sometimes a mixture of the two. As stated above, these gases are really suited only for non-ferrous metals like aluminum. Carbon dioxide is a low-cost alternative to argon that gives a wide arc that isn’t very stable and can sometimes cause spatters.

Different gases result in different types of welds. Argon gas has low thermal heat conductivity and a shallow wide penetration. It has a very smooth arc. Helium gets very hot. It has good weld productivity and mild penetration. Carbon Dioxide has a deep narrow penetration with a harsh arc that works well when welding out of position. Adding a mixture of Carbon Dioxide to Argon or Helium deepens the penetration and stiffens the arc, which in turn also improves out of position welding. Adding oxygen to Helium or Argon deepens the penetration of the weld. Adding Helium to any gas ups the heat of the arc.

Workplace Location

The condition of the environment you’ll be working in is a very important factor when considering which welder to purchase. If you’ll be working outdoors or in windy conditions, an MIG welder may not be right for the job. Wind can affect the quality of the weld as it will cause you to lose the shielding gas and create porosity, or tiny holes, on the weld bead. Always choose a wind-free, but well-ventilated area to perform a welding job. It’s also important to implement proper workplace safety conditions and precautions when working with hazardous welding materials.

Welder Voltage

For industrial welding, you’ll probably want to go with a 230 volt welder, or a multi-power option. These welders are more suitable for heavy-duty jobs. If you’re buying a welder for home use, the ideal range of MIG welder will be 115 to 120 volts. The machines are more suited for smaller welding jobs. They also use the normal 3 pin household plugs. They usually need a plug outlet with 20 or 30 amps good ground connection fused. If you have 120 volts circuit available at home, an MIG welder that runs on 110 to 115 volts is optimum.

MIG Wire

Some MIG welding machine require a flux core wire, which doesn’t need a shielding gas, to feed through the MIG gun and into the weld pool. The sizes of available wires vary, but thicker wires generally produce a higher quality weld. As the flux core wire melts in the weld, the flux rises to the surface and creates a protective coating on the weld. Although this reinforces the strength of the weld, this layer of flux will then be removed and will leave the weld with a scratched up appearance. This makes flux cored welding inappropriate for welds where a neat appearance is important. In these cases, gas-shielded MIG wire is still the best option.

Do You Need a Spool Gun?

If your project requires you to weld aluminum, you’ll find that the wire often gets jammed in the MIG torch as it’s being fed from the feeder. This can be remedied by attaching a spool gun to your torch, which places the wire several inches away from where it should come out of the torch. This helps to eliminate wire jams.

While welding aluminum with a spool gun does make the process easier, it’s still no simple task. Learning to MIG weld aluminum with a spool gun often requires many hours of practice to master, as there are many different things that can go wrong.

Some in the welding business say that spool guns aren’t necessary to MIG weld aluminum with a little patience and a good technique. They claim that spool guns are bulky and expensive, and that there are ways to adjust your settings to weld aluminum with a hobby welding machine without the gun.

How Does a MIG Welder Work? Choosing a MIG Welding Machine

And there you have it. When choosing an MIG welding machine, be sure to keep these deciding factors in mind. If you’re curious about which brand of MIG welder is best, there is no general consensus. It all really depends on the particular person’s welding conditions and preferences. Generally, there are several brands that are considered reliable in quality: these are ESAB, Hobart, Lincoln, Miller, and Thermal Arc.

No matter what kind of welding job, there’s an MIG machine out there that’s right for your workplace, warehouse, or workshop. Using this guide, you’re now ready to make a decision about which MIG welding machine is right for your particular needs. Remember to always wear safety gear and take extra precautions when working with hazardous welding materials, and happy welding.

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