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While the sight of sparks flying around a welding helmet and thick gloves might be common across all types of welding tasks, there are actually different kinds of welding used depending on the situation, material, and goal of the weld. If you don’t use the correct welding method, you risk weld failure and the frustration of wasted effort.
The two most common welding methods are MIG welding and TIG welding. While both types of arc welding are used by amateurs and pros, welders choose each method for different reasons. Here’s are the most important differences between MIG and TIG welding.
What is MIG welding?
MIG stands for “metal inert gas,” and it’s also known as gas metal arc welding (GMAW). MIG welding machines generate a powerful electrical current that runs through a handheld torch. The torch supplies the welding gas and automatically feeds the MIG welding wire. This wire creates an electrical arc that melts the metal being joined and provides filler material to strengthen the joint. A ground clamp is attached to the workpiece to protect the welder from shocks.
When to Use MIG Welding
MIG welding is the best choice for large jobs. You can deposit great quantities of filler quickly and weld substantial thicknesses in a single pass. MIG wire is fed automatically through the welding gun from a spool that can hold hundreds of feet of wire, so MIG welding is almost always the better option for a long run of welding.
Generally speaking, the speed and power of MIG welding are better suited to more substantial projects. MIG is a great choice for hobby welders interested in auto repair, building steel furniture, or creating steel sculptures for the garden.
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What is TIG welding?
TIG is an acronym for “tungsten inert gas”; TIG welding is also referred to as gas tungsten arc welding (GTAW). With TIG welding, the electrode delivering the electrical charge is made of tungsten, and, unlike MIG wire, is non-consumable. An extra filler rod must be used, which the welder holds in their other hand. Coordinating the two requires greater concentration than when working with MIG.
When to Use TIG Welding
TIG welding offers greater precision, both in terms of machine-provided adjustments and welder control, resulting in smaller, neater welds. Once the technique is mastered, TIG welders can achieve a quality weld that requires little or no cleanup work before finishing. Because each TIG welding rod is around 3 feet long, TIG welding is best for small, detailed pieces and for creating a more finished look.
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Differences Between MIG and TIG Welding
Even though they sound similar, and the welding machines look alike at first glance, MIG and TIG welding are very different. In truth, the question of which type of welding is best depends upon which is the most appropriate for the job at hand.
Understanding what’s the difference between MIG and TIG welding is key to the success of any project. Here’s a quick look at TIG vs. MIG welding:
| MIG Welding | TIG Welding | |
| Equipment cost | Less expensive | More expensive |
| Difficulty/skill level | DIY-friendly welding | Skilled welding |
| Uses | Heavy-duty welds | Detailed welds |
| Speed | Faster | Slower |
| Size | Bigger welds | Smaller welds |
| Aesthetics | Less finished-looking | More finished-looking |
Welding Gas
Both TIG and MIG welding require welding gas, which acts as a shield to protect the weld from impurities in the air, but there are differences in the gas mix used in each type of welding.
MIG Welding
MIG welding gases are inert, so they have no impact on the chemical reaction within a weld. The most common is a mix of argon and carbon dioxide. The purpose of MIG welding gas (also called shield gas) is to protect the molten metal (the weld pool) from impurities present in the air. Hydrogen, nitrogen, and oxygen in the air around us can cause excessive spatter (molten metal thrown out of the weld) and porosity (air bubbles within a weld), the latter of which creates weaknesses in the finished job.
TIG Welding
TIG welding also requires gas to shield the weld from impurities, but the shield has the added function of preventing the TIG electrode from overheating. TIG welding gas is typically composed of argon or a mix of argon and helium (another inert gas). Argon and hydrogen are used when TIG welding stainless steel.
Weld Speed
Speed is another factor to consider when choosing between MIG and TIG welding.
MIG Welding
MIG welding is faster than TIG. A MIG welding machine feeds welding wire through the torch automatically, at a speed set by the user. Beginners can slow the wire to suit their skill level, while professionals can speed it up to maximize productivity.
One drawback of MIG welding is that it doesn’t produce such a neat weld, so extra time may be required to clean things up for painting or electroplating.
TIG Welding
TIG welding is a slower process than MIG welding. This is partly due to the welder’s need to coordinate the actions of both hands. There’s also the physical restriction of manually feeding the filler rods into the weld pool one at a time.
The upside of TIG welding is greater control. The weld pool is comparatively small, making TIG a better choice when the appearance of a weld is important. This process also makes it possible to weld thinner material than can be done with MIG.
Weld Strength
There are differences between TIG weld vs. MIG weld strength, and here’s why.
MIG Welding
Any properly formed weld is extremely strong. As the adage says, the weld is actually stronger than the original metal. This is true of any good MIG weld, but care is required. Although MIG welding produces a comparatively large and easy-to-manage pool of molten metal, trying to weld too quickly can produce uneven penetration that leads to weaknesses.
Protection offered by the shield gas is a vital element in weld strength. Any wind can disrupt this bubble and let in impurities, so standard MIG welding cannot be performed outdoors. One solution for this is a gasless MIG welder, although these can’t be used for MIG welding aluminum.
TIG Welding
Because TIG welding produces smaller and neater welds than MIG, it’s ideal for welding thinner materials. Also, the intensity of the welds penetrates material more deeply, so TIG weld strength is greater.
This is particularly true when TIG welding lightweight aluminum, as well as when working with smaller dimensions. MIG can simply be too powerful and can burn right through the material, whereas TIG provides the necessary precision.
The argon and argon/helium shields used in TIG welding are heavier than the argon/carbon dioxide mix commonly used with MIG welding, so it’s possible to TIG weld outdoors in calm conditions. However, it can still be a challenge. One widely available solution is a combo machine designed for outdoor use that includes stick welding, another option among the different types of welding.
Pros and Cons of MIG Welding
Here’s a quick look at the pros and cons of TIG welding vs. MIG welding.
Pros
- MIG welding is faster.
- MIG welding is DIY-friendly.
- MIG welding is less expensive than TIG.
Cons
- MIG can simply be too powerful and can burn right through the material.
- MIG isn’t known for producing a neat weld.
- MIG isn’t ideal for small welds.
Pros and Cons of TIG Welding
Pros
- TIG produces smaller and neater welds than MIG.
- TIG offers greater control than MIG.
- TIG can weld thinner material than MIG.
- TIG penetrates the material more deeply than MIG.
Cons
- TIG welding is a slower process.
- TIG requires greater skill than MIG.
- TIG is more expensive than MIG.
FAQ
Q. Is MIG or TIG welding better?
The best type of weld depends on the situation. MIG is better for bigger welds, and is a better choice for those who are new to welding. TIG welding is better for precision welding and welders with experience.
Q. Can I MIG weld aluminum?
Aluminum can be successfully MIG welded, but control can be difficult, particularly with thin sheet metal.
Q. Do MIG welders need gas?
Not all MIG welders require a separate gas supply. With gasless MIG (or flux-core welding), the welding wire is coated with chemicals that form their own shield as the wire melts.
Q. Which type of welding is the strongest?
TIG welding can be stronger when joining small items and welding aluminum, but MIG welding is stronger for heavy-duty structures.
Q. What type of welding is best for beginners?
MIG welding is considered the best type of welding for beginners. The welding technique is easier to learn and more forgiving.
Q. What do I need to know about welding safety?
Welding safety and appropriate personal protective equipment (PPE) are important. A welding helmet, welding jacket or apron, and proper welding gloves are all vital for avoiding burns and a painful eye injury known as “welder’s flash” or “arc eye.” Fortunately, the same high-quality welding PPE can be used for all forms of welding.
