What is MIG Welding and How Does it Work?
MIG Welding Explained
MIG (Metal Inert Gas) welding is an extremely common welding process that is sometimes called Gas Metal Arc Welding (GMAW) – but what is MIG welding all about? This process makes use of an electric arc to fuse pieces of metal together. The method is used widely across many different industries due to its speed, ease of use and ability to create good quality, strong welds.
In this blog we will discuss how MIG welding works and compare it to other welding services that we also provide here at Salamander Fabrications.
Key Components of MIG Welding
- Welding Gun: Also called a welding torch, this holds the wire electrode and directs it to the welding area. It also releases a shielding gas that protects the weld from contamination.
- Wire Electrode: A consumable wire is continuously fed through the gun that melts during the process, becoming part of the weld.
- Shielding Gas: A gas is used to shield the molten weld from oxygen and other atmospheric contaminants. This is typically an inert gas like argon, or a mixture of gases like argon and carbon dioxide. This helps prevent defects and improves weld quality.
- Power Supply: A constant voltage power source is required, typically with a direct current (DC), to maintain a steady arc and consistent weld quality.
Benefits of MIG Welding
- Speed: A continuous wire feed allows for faster welding.
- Versatility: Can be used on various metals, including steel, aluminium, and stainless steel.
- Clean welds: Shielding gas minimises slag and produces cleaner welds.
- Ease of use: All of our welding operators are highly skilled and qualified, so they know what they are doing. However, despite requiring skill, MIG welding is relatively easy to learn.
How Does MIG Welding Work?
Welding Machine Setup
MIG welding uses a constant voltage power supply. A spool of wire that acts as an electrode is fed through the welding gun at a controlled, continuous rate. Argon, or a mix of argon and CO2, also flows through the welding gun as shielding gas, surrounding the wire as it exits. This shields the weld area from atmospheric contamination.
Creating the Arc
The wire exits the welding gun when the welder pulls the trigger. An electrical arc is created between the wire and the metal workpieces being worked on. The arc generates heat, which melts both the wire and the workpieces, making them fuse together.
Shielding
The shielding gas protects the molten weld pool from reacting with the oxygen, nitrogen, and hydrogen in the air. If this were to occur, it can cause defects like porosity, spatter, and weakness in the welds
Weld Formation
The welder will move the welding gun along the joint and the wire will continuously melt, leaving molten metal in the weld pool. When the pool cools and solidifies it forms a strong bond between the metal pieces being worked on.
How is TIG Welding Different?
TIG (Tungsten Inert Gas) welding, also called Gas Tungsten Arc Welding (GTAW), is another popular welding process. It shares some similarities with MIG welding, but there are some key differences in the:
- way it works
- skills required
- types of projects it’s suited to
Key Differences Between TIG and MIG Welding
| MIG Welding | TIG Welding | |
| Electrode type | Uses a continuously fed consumable wire electrode that melts and becomes part of the weld. | Uses a non-consumable tungsten electrode that does not melt. A separate filler rod is often used instead to add material to the weld. However, some TIG welding processes can be done without filler metal. |
| Welding process | The wire electrode is fed through the welding gun, and an electric arc is created between the wire and the workpiece. The wire melts, filling the weld joint. | The welder manually holds the torch with the tungsten electrode in one hand and the filler rod in the other (if filler is used). The electric arc is struck between the tungsten electrode and the workpiece, and the welder controls the addition of filler metal by dipping the rod into the weld pool. |
| Shielding gas | Typically uses an inert or semi-inert gas to shield the weld area. This may include argon, CO2, or a mixture of both. | Uses pure argon for most metals, but sometimes helium or a mixture of argon and helium is used. |
| Control and precision | Easier to learn and faster, but offers less control over appearance and penetration. | Provides greater control over the welding process, allowing for precise, clean welds, especially on thinner materials. It also allows for better control over the heat input, reducing the risk of warping or distortion. |
| Applications | Commonly used for thicker materials, general fabrication, automotive work, and projects where speed is a priority. | Ideal for thin materials like aluminium and stainless steel. Preferred for high precision work, such as aerospace and automotive related projects, and where an aesthetically pleasing weld is required. |
| Weld quality | Good quality welds, but may result in more spatter. May require post-weld cleanup. | High quality welds with no spatter. Post-weld cleaning often not required. |
| Difficulty and skill level | Easier to learn and faster to master, making it suitable for beginners. | More challenging to master due to the need for coordination and precise control between both hands. |
MIG Welding Compared to Other Welding Services
Spot Welding
Spot Welding is more specialised, focusing on quickly and efficiently joining thin metal sheets with discrete welds. This makes it the ideal method for mass production environments like automotive manufacturing.
Other differences include:
- Spot welding does not use filler or shielding gas. The weld is formed by pressure and heat generated by an electric current.
- Spot welding can be automated, especially in manufacturing processes. Whereas with MIG welding, the welder usually controls the movement of the welding gun, making it suitable for both automated and manual applications.
- Primarily used for joining thin sheets of metal, whereas MIG welding is suitable for a wide range of applications, including construction, automotive repair, and metal fabrication services.
- Spot welding is typically used to create individual weld spots rather than continuous welds.
- Less suitable for high stress or load bearing applications compared to MIG welding.
Robotic MIG Welding
MIG welding and Robotic MIG welding are closely related but with one primary difference – Robotic MIG welding has a higher level of automation. The same basic MIG welding principles are applied, but the inclusion of robotic technology improves efficiency, consistency, and application.
Other differences include:
- In robotic MIG welding, the welding process is controlled by a robotic arm programmed to follow precise instructions, rather than a human welder.
- With MIG welding, the quality of a weld heavily depends on the skill and experience of the operator. On the other hand, a robot will follow a pre-programmed path precisely, ensuring consistent weld quality across multiple identical parts.
- A robot is less able to adapt to unexpected situations, variations, or non-standard operations. Whereas human welders can be trained to handle different materials, positions, techniques and unexpected situations.
- Robots can operate continuously, making them perfect for repetitively producing large quantities of identical parts, at speed. MIG welding is more suitable for projects where welds require special attention.
- Robots do not get tired! They can work consistently at speed, for as long as you need them to, with no drop in quality. This leads to significant time and cost savings in high volume production.
Expert Welding Services at Salamander Fabrications
Here at Salamander Fabrications we have over 50 years of welding experience. Our welding operators are highly skilled coded welders with experience working with steels, stainless steels, aluminium, and many other materials.
For more information or advice on your next project please feel free to contact us, give us a call on 01484 843599 or send an email to sales@salamanderfabs.com.
