what is a mig welder

So, what is a MIG welder? Also, why would you go ahead and use one in the first place? Also, which materials can be used with this approach?

These are essential questions to ask, and this is the subject we are going to explore. By the end, you will understand everything that there is to know about a Metal Inert Gas (MIG) welder and the welding process itself, from the wire feed to the weld pool and everything in between.

So, where do we begin?

Metal Inert Gas (MIG) Welding

Let’s start by looking at the name because Metal Inert Gas (MIG), and it’s a welding process that uses electricity and heat to weld pieces of metal together.


It has many advantages associated with this type of welding. It’s also a welding approach that has been used for around a century, so it’s not something that is brand new on the market.

Moreover, MIG welding is employed by both professional industries and the do-it-yourself welder at home for small tasks. Its versatility is quite amazing.

A Sub-Type of Gas Metal Arc Welding

As a quick note, MIG is also a sub-type of gas metal arc welding. It is also known by several other names, but they all refer to the same welding process being used, and they all deliver the same end results.

Other Names Used for MIG Welding

It may also be known by various other names, including gas metal arc welding, spray welding, short-circuit welding, and flux-cored arc welding. No matter the name, it all represents the same thing.

The Basic Principle of MIG Welding

The basic principle behind MIG welding is easy to follow. You use electricity, an electrode, and metal. An electrical arc is created between the electrode and the metal. In this instant, the welding metal becomes negative in the electrical arc, while the electrode is positive. It creates a short-circuit between the two leading to that arc.

But this method is a powerful form of welding.

The arc is capable of generating enough energy that it successfully melts the electrode wire. It then welds the wire onto the metal, and this is the foundation of all welding processes.

After the heat source is taken away, the weld beads manage to cool, and this then creates the weld.

Later, we will look at the material that can be used with this method, such as carbon steel, as an example, while you will also see that creating a weld joint is easy when you use MIG welding.

The Advantages of MIG Welding

MIG welding does have many advantages.

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First, there’s practicality. Anyone with the power source and basic materials can carry out the weld. Also, the entire process is quick and easy to do, even if you are in a garden shed. There’s no need for too much equipment, either.

It’s also generally cheaper than other forms of DIY welding.

But another key advantage is how MIG welding can be used on thicker materials, but more on that later.

The Welding Gun

In this instance, the gun is a simple affair, and it’s easy to use even for those new to using this type of machine.

The gun uses heat and wire, with the gun plugged into a power source. The voltage in the gun is used to help create the spark, while the heat creates the molten metal from the wire used in the weld.


The molten metal comes out of the wire electrode and creates the weld pool. After contact with the metal to be welded, the circuit is completed between the positive electrode and the negative metal.

If you look closely at the weld pool, you will also notice the shielding gas, but that will be discussed shortly.

How the Wire Is Fed Into the Gun

As we are talking about the advantages, it makes sense to talk about how the weld is created continually.

The key is how the wire is fed into the gun. By being continuously fed, it means that MIG welding is perfect for larger-scale jobs. There is no break in producing that weld bead, so that’s why the approach is used in a wide range of industries.

The Shielding Gas

This form of welding uses shielding gas, and there are four different versions most commonly used with this approach.

The most common of the gases used are argon. However, argon is often mixed with carbon on a 75% to 25% ratio. It is popular as it appears to strike a balance between ease of supply and the quality of the finished weld. The only problem is that other gases are less expensive, which may be a factor for some individuals.

It’s worth noting you can use 100% argon, but the mix we mentioned is far more effective.

Other gases available will often include carbon dioxide. The problem here is that CO2 can make the welds weaker at the joint over time, so it’s best to avoid this option. Once again, go for the mix with argon to produce that stronger contact.

Why Use Shielding Gas?

If you are unsure why you should use shielding gas with MIG welding, let’s quickly explain.

Shielding gas stops the weld pool from being exposed to the natural elements in the air. The problem is that the air can create extra spray transfer of the weld pool. It can also make it harder for the weld to stick to the material.

Without gas, the wire weld becomes less effective, and the entire process is weakened. That is something you need to avoid.

The Difference Between MIG and TIG Welding

Before we go any further, we also need to mention the difference between MIG and TIG welding, also known as Tungsten Inert Gas welding.

The main difference is in the actual arc that’s used. With MIG welders, there’s a feed wire used via the electrode, which constantly pushes the wire through to create the weld.

It doesn’t happen with TIG welding. Instead, this form of metal welding uses a different welding arc. The arc involves two different metals in the form of long rods. It’s these rods that will then weld the metals together.

TIG welding can be used on a wide range of metals, but it cannot work effectively with thicker materials. That limits its use quite considerably.

MIG Welders and Metals

Stainless steel, carbon steel, sheet metal, and aluminium are just a few of the metals that can be welded with mig welding. The thickness of the material is also important, but MIG welding allows you to work with thicker metal than other options.

But here’s another fascinating point about the welding process.

This Approach Uses Filler Metal

We mentioned earlier that this approach uses wire to create the weld, but that’s not the complete picture. Instead, it uses filler metal rather than fusing, which is another form of welding using different technology, making a difference.

The wire feed itself acts as the filler. Thanks to this, it means the metal being welded will not have to be heated up to the same extent as other methods. It makes things far more practical and efficient.

However, the lack of heat doesn’t affect the strength of the welding bond.

The Effectiveness of MIG Welders

But what about the effectiveness of this particular machine, and what are the welded materials like?

There is a reason why MIG welding is used in so many industries, and it’s because of how brilliant it is at producing a quality results.

MIG Welding Uses Variable Speed

The effectiveness of MIG welding is partly due to the speed at which the wire can be fed continuously through the electrode.

The MIG welding gun is designed to be used for a prolonged period. It means it can be used to process more welds on an industrial scale.

For industries where producing material must be done at pace and regularly, MIG welding is the go-to approach.

What Do You Need?

So, what do you need to start with MIG welding, even in your small way? Well, aside from the materials such as steel or other metals, you also need the power and the right gun for this kind of welding. You will also require the wire for the process and look at the contact tip that comes with the wire electrode.

Apart from those few things, you will not require too many other items to create that welded joint.

Learning How to Handle the Equipment Is Easy

Finally, it’s worth noting that learning how to handle this equipment is easy. The machine used to create these welds is straightforward enough for even a beginner to master in next to no time.

You can control the speed at which the wire is fed. You will find it easy to manipulate the position at which the weld pool meets the other materials. The heat is also controlled at all times when creating the welding joint. Even the power level can be adjusted on certain models, which means you have even greater control over the wire electrode.

Try It Yourself

The only thing left to do is to try out MIG welding for yourself. As long as you have the basic equipment and a power source, you can get to work with stainless steel or any of the other materials mentioned earlier.

Just keep an eye on the wire feed, and take time mastering the speed. Considering the quality of the weld, you will be able to produce it even in your garden shed.

Time to Upgrade

What is a MIG welder? Knowing it is just the beginning of your welding journey. Like any tool, it is essential to understand how a MIG welder works and its limitations to make the most of it.

Have you used a MIG welder before? What projects have you completed using this tool? Send us a message below.

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