MIG Welding Basics
Estimated reading time: 3 minutes
When it comes to MIG welding, it’s important for new welders to start with the basics to set a solid foundation for success. The process is generally forgiving, making it simpler to learn than TIG welding, for example. It can weld most metals and, as a continuously fed process, offers greater speed and efficiency than stick welding.
The very first consideration for new welders is welding safety. It is imperative to read and follow all labels and the equipment Owner’s Manuals carefully before installing, operating, or servicing welding equipment. Welders must wear proper eye protection to avoid arc flash burns and sparks. Always wear safety glasses and a welding helmet set to the appropriate shade level. Proper personal protective equipment attire is also critical to protect the skin from electric shock and burns. This includes:
- Leather shoes or boots.
- Leather or flame-resistant welding gloves
- Flame-resistant welding jacket or welding sleeves
Adequate ventilation is also an important safety factor. Welders should always keep their head out of the weld plume and be sure that the area in which they are welding has adequate ventilation. Some type of fume extraction may be needed. Fume extraction guns that remove the exhaust at the arc are also helpful, and are very efficient compared to floor or ceiling capture.
Welding transfer modes
Depending on base material and shielding gas, welders can weld in various welding transfer modes.
Short circuit is common for thinner materials and operates at lower welding voltage and wire feed speed, so it is slower than other processes. It also tends to produce spatter that requires post-weld cleaning, but overall, it is an easy process to use.
Globular transfer operates at higher wire feed speeds and welding voltages than short circuit and works for welding with flux-cored wire with 100% carbon dioxide (CO2) (see details on CO2 in next section). It can be used on 1/8-inch and thicker base materials. Like short-circuit MIG welding, this mode produces spatter, but it is a fairly fast process.
Spray transfer offers a smooth, stable arc, making it appealing to many new welders. It operates at high welding amperages and voltage, so it is fast and productive. It works well on base materials that are 1/8 inch or more.
Welding shielding gas
In addition to protecting the weld pool from the atmosphere, the type of shielding gas used for MIG welding impacts performance. Weld penetration, arc stability and mechanical properties depend on shielding gas.
Straight carbon dioxide (CO2) offers deep weld penetration but has a less stable arc and more spatter. It is used for short circuit MIG welding. Adding argon to a CO2 mixture allows for use of spray transfer for higher productivity. A balance of 75% argon and 25% is common.
Beyond the basics
Along with practice, knowing some key information can help new welders better understand the MIG welding process. It’s also important to be familiar with the equipment, including MIG welding guns and welding liners. Understanding how to select and maintain this equipment can go far toward establishing good welding performance, quality and productivity.
This is the first article in a three-part series on welding basics. Read article two, MIG Welding Glossary: Terms to Know and article three, MIG Welding Techniques: What to Know.