How Does a MIG Welder Work: Uses, Benefits, and Tips

Last Updated on January 10, 2023

Welding is a standard process used in manufacturing, metalwork, and construction. The process of welding creates a powerful bond and is used to join surfaces together. There are different types of welding, and one of the most common is MIG welding.

How does a MIG welder work? Read on to find out everything you need to know about MIG welding!

What Is MIG Welding?

At its most basic, MIG (Metal Inert Gas) welding is the process of melting two pieces of metal together electrically to form a solid joint. The creation of molten metal that reforms and hardens produces a solid bond that offers excellent tensile strength for thicker metal work like carbon steel and stainless steel.

MIG welding is a sub-process of GMAW – Gas Metal Arc Welding. The other sub-process underneath GMAC is MAG – Metal Active Gas Welding.

The idea and basics of GMAW were developed during the 19th century. This was instigated by the discovery of the electric arc by Humphry Davies in 1800. Basic welding processes and tools were developed that utilized carbon electrodes and then metal electrodes. Initially, shielding gas was not used, as little was understood about welding atmospheres.

Further developments in 1948 saw the first actual usage of MIG welding. The Batelle Memorial Institute produced a MIG welder that utilized an argon carbon dioxide gas for shielding. From this point, the process was improved, which included the trial of different shielding gasses, currents, and power sources.

How Does a MIG Welder Work?

First, let’s look at the MIG welding technique. You must know the basics of this welding technique to understand how the metal inert gas MIG machine works. The following are the basics process involved in MIG welding:

• An electrical arc is created between a positive anode (the electrode wire) and a negative cathode (the metal).
• The welding wire is then melted via the electric arc and turned into molten metal.
• The molten metal is deposited onto the metal surface to create the final weld.
• The electrical arc is stopped, and the weld pool cools and solidifies.

As you can see, the main part of MIG welding is the utilization of negative and positive charges to create an electrical arc that melts the metal. In addition, a power source provides a direct current to the wire electrode. This causes the welding wire to melt, and a weld pool is created on the surface of the materials you wish to weld.

Once the wire electrode is turned off, the weld pool cools and thus forms the welding joint. Molten metal forms a powerful bond and is the main reason why MIG welding is so practical.

However, there is also a vital shielding process that improves the integrity and strength of the weld. When a weld pool is exposed to our atmosphere, the gases within the atmosphere weaken it and change its composition. This ultimately weakens the strength of the weld. Therefore, MIG welding also includes the use of shielding gas.

The shielding gas is pumped along the same transfer feed tube as the fire feed. This shielding gas envelopes the weld pool and protects it from any atmospheric interference. Different combinations of shielding gases are used. However, the most common shielding gases for a welding MIG are carbon dioxide and argon.

A Typical MIG Welder

With inert gas welding, a typical MIG welder has four main components listed below. The power source and systems are generally housed within a mobile MIG welding unit. These are typically on wheels that allow users to weld in a wide range of positions.

The MIG Welding Power Source

The power source has a standard polarity and voltage type. The voltage used is DC (direct current). The polarity is positive, i.e. the direct current flows from the positive electrode in the welding machine to the negative cathode of the metal. The power source is also known as a contact voltage power supply. Users can alter the voltage to change the usage of the machine.

Wire Feed System

The wire feed system is also an essential aspect of MIG welding. The welding wire is usually distributed on a spool.

As you pull the trigger, the spool rotates, and more welding wire is pushed out. You can get various wire diameter spools, but the most common wire diameter is 0.23 to 0.45. Of course, which diameter wire you choose depends on the size and quality of weld you wish to produce. Regardless, the inert gas welding wire is usually available in spools as opposed to single strips.

Welding Handle and Trigger

The piece of kit you use to create the weld is the handle and trigger. The handle and welding gun are connected to the main machine. During the MIG welding process, you pull the trigger. After this, several things happen:

• It releases the inert metal gas for shielding.
• The wire is fed through the contact tube.
• The electric arc is also generated to melt the metal.

Shielding Gas and Distribution System

The last part of this type of machine is the shielding gas. The three types of gas that are commonly used include carbon dioxide, argon, and helium.

A mixture of any type of gas may be used depending on the material being welded. For example, a combination of carbon dioxide and argon may be used. When the wire is fed and the electric arc created, the gas is also continuously fed to protect the weld.

What Are the Benefits of MIG Welding?

Now that you understand these welding techniques, we can look at why MIG welding is popular. The MIG welding technique has many benefits compared to TIG (Tungsten Inert Gas) welding. It is versatile, used for welding a range of non-ferrous alloys, and offers a quick welding metal solution. The following are the main advantages of these welding processes:

Faster Welding Speeds

MIG welders and this position welding process are fast. As described above, the welding machines and constant voltage allow for quick, repetitive welds. Also, because the welder doesn’t need to hold filler metal in their other hand, they can operate the MIG welding arc more effectively.

No Entrapment of Welding Slag

Because no flux is used, there is no chance for the slag to become entrapped in the welding material. As a result, the weld metal is pure and of a higher quality.

Minimal Loss of Welding Alloy

Due to the internal process, there is also minimal wastage. The gas shield protects the welding arc. Therefore, there is virtually no material spatter on the finished metal, where the weld joint is.

Multiple Uses With Various Base Metal Alloys

This electrode positive welding process can also be used with various types of metal. Therefore, it is versatile in comparison to some other limited welding processes.

Versatile Uses for the Welding Torch

The equipment is also versatile. You can use a welding MIG in various modes, including automatic, manual, and semi-automatic. This means the tool can be adapted to different skill levels and for other tasks easily.

Less Change Over Time

The setup and operation of MIG welding are generally quicker. This is because the wire is continuously fed. With TIG welding, you often have to replace the welding wire and have new wire strips cut and ready to use. In addition, with MIG welding, you need to fit a wire spool!

Tips for Using a MIG Welder

MIG welding requires skill, patience, and concentration. It is relatively simple to learn. However, there are many tricks and tips you can utilize to improve the quality of your welds. We have listed some of them below:

1. Ensure the Welding Surface and Welder Are Cleaned Thoroughly

The main factor in the quality of a MIG weld is the surface of the metal being welded and the cleanliness of the welder itself. Therefore, if you want the best quality weld, you must look after your tools and pay attention to the welded material.

First, regardless of the type of metal, the surface must be clean and exposed. In some instances, you may even need to grind the material beforehand. For example, if the metal has old paint on it or rust, this could weaken the weld and affect the end. Inspect the weld metal and make sure it is relatively bear. Also, ensure that the wire electrode, wire feed, and other parts of the tool are clean.

2. Always Use Two Hands!

Compared to stick welding (TIG), MIG welding offers the advantage of using two hands. However, many people often still only use one hand! Therefore, where possible, always use both of your hands. For example, you can use one hand as a steadying block to rest your other hand on.

Alternatively, you can hold the welding machine with both hands for improved stability. Either way, with your offhand free, you should make use of it regardless of improving your welding quality and speed.

3. Listen to the Sounds Your Welder Is Making

As with many tools and machines, listening to their function is a clear indicator of their status and how effectively they are working. With MIG welding, you should hear a steady and consistent buzz. However, you may hear several other sounds pointing towards a different defect or incorrect setting with the MIG welding tool.

First, a consistent low hiss could be a result of the voltage setting being too high. Alternatively, a high, raspy sound may result from the opposite – the voltage setting is too low. Finally, if you hear a sound like a machine gun – a crackling sound, this points towards amp settings being too high. Over time, you will learn to recognize these sounds and tune the machine as you work.

4. Replace Contact Tips Often

The contact tips and contact tube become worn over time. If you continue to use the same contact tips, your MIG welding quality could deteriorate also. Luckily, contact tips are generally one of the cheapest parts of the welding machine.

It is advisable to keep a stock of contact tips and keep a handful with you whilst using the MIG welding machine. Replace the tips often as worn tips can result in an irregular welding arc. For example, you can see a tip is worn when the shape has become oval.

MIG Welder FAQs

To help you understand how a MIG welder works, listed below are some of its frequently asked questions.

What Is MIG Welding Used For?

Generally, this process is used for thicker materials like aluminium, stainless steel, and carbon steel. TIG welding, on the other hand, is mainly used for thinner materials like sheet metal.

Which Welding Process Is Easier, MIG or TIG?

It is generally accepted that MIG welding is easier and faster. This is because the process requires only one hand, although it is always advisable to use both. Meanwhile, with TIG welding, you must control the welding gun with one hand and hold the metal filler material with your other hand.

Which Is the Stronger Bond, MIG or TIG?

TIG welds are considered to be more precise and stronger. However, this doesn’t diminish the effectiveness or strength of a MIG weld at all – they are perfectly acceptable and create a strong bond.

Form a Strong Bond Wit a MIG Welder

How does a MIG welder work? It melts metal to make a pool that will join two base materials. You have read about the basic definition of MIG welding and broken the process into two sections – the welding process itself and a breakdown of a typical MIG welder. With this information and the tips for using a MIG welder in mind, you will succeed in your DIY projects sooner than you expected!

What projects will you use the MIG welder for? Have you already used it with some of your projects? How was your experience? Let us know in the comments!