TIG Welding Vs MIG Welding- Which One to Use When

By Jayden Mark   

While there are many welding methods out there, a majority of metal bonding uses TIG or MIG welding. What’s the difference between these methods, and which one is the best choice?

What is TIG Welding?

“TIG” stands for Tungsten Inert Gas. It’s also referred to as Tungsten Arc Welding (GTAW). It uses a non-consumable tungsten electrode to heat the metal, while filler wire is fed into the weld pool. Inert gas flows from the tip of the torch over the pool to prevent oxygen contamination.
 
TIG welding can use DC positive, DC negative and AC power. Changing the power source alters how the weld behaves, letting users choose between intense heat for better penetration, a wider heat spread for more surface contact, or intermittent pulses to prevent warping.

What is MIG Welding?

“MIG” stands for Metal Inert Gas, but this term is also applied to Metal Arc Welding (GMAW), which uses gases that can react to the weld, and wire feed welding, which doesn’t use gas. Most MIG welding machines can do all three types of welding.
 
MIG welding uses the filler wire as the electrode. The generator makes DC electrode positive current, sending electricity to the welding gun, so that heat is concentrated in the electrode.

Which Type of Welding is Better for Outdoor Work?

MIG welders can use flux core wire on steel, eliminating the need for a shielding gas. This makes it possible to weld in windy conditions. TIG welding requires coverage with shielding gas before, during and after the weld. Even drafts inside buildings can interrupt shielding coverage, leading to oxidation and slag, making it unsuitable for outdoor use.

Which Type of Welder is More Portable?

Small flux core-only MIG welders are lightweight, and can be powered using a small generator or household outlet. While TIG welders don’t need a wire feeder, they require gas and can only be used indoors.

Which Type of Welding is More Versatile?

MIG welders can handle most metals with the right setup. Flux core welding only works on steel. Most welders can bond aluminum when they’re outfitted with a wire feeder that can handle soft aluminum filler wire. MIG welding only works with pieces made from the same type of metal.
 
TIG welding can bond almost anything, including dissimilar metals. This makes them popular in shops that need to weld a wide range of materials.

Which Type of Welding is Better for Dirty, Painted or Corroded Metal?

MIG welding isn’t the best at blasting through contaminates, and it does nothing to paint. However, it can handle mild corrosion when used with wire loaded with cleaning agents.
 
TIG welding needs a perfectly clean surface to form a bead. Even virgin metal needs to be wiped down or scuffed to remove any residue from handling or manufacturing.

Which Type of Welding is Easier to Set Up?

MIG welding needs a reasonably clean surface. Since only one hand is needed to operate the gun, the other hand is free to hold the pieces being welded. In many cases, there’s no need to set up a jig.
 
TIG welding is very sensitive to oxidation. Some metals need to be completely surrounded with an inert gas to prevent slag formation, even on the back side of welds. Welders need to use one hand for the torch and the other hand to feed the wire. When using welders with a foot pedal, the welder needs to be sitting or standing in a position that allows easy control of the pedal. As a result, the pieces being welded need to be self-supporting or set up in a jig.

Which Type of Welding Makes Better Welds?

On MIG-compatible welding jobs, there really isn’t any difference in the function and strength of a MIG or TIG weld. However, TIG machines offer fine control of heat transfer and the weld pool, and the resulting weld has the same corrosion resistance as the surrounding metal. This makes it the best choice for welding difficult materials, as well as welding materials that are exposed to corrosive environments.

Which Type of Welding is Easier to Learn?

The hardest part of learning to MIG weld is adjusting the welder. Users have to balance wire feed speed and power to get a good bead. However, there are only three basic welding techniques to learn with little variation in control while welding.
 
TIG welders have several settings, including electricity type, amperage, shielding gas flow rate and pulse rate. During the weld, the user needs to vary amperage to control the weld pool. TIG welding is sensitive to oxidation, so welders use pre- and post-flow of shielding gases to push away oxygen. It’s easy to forget to hold the torch in place outside of welding to prevent oxygen from reaching the weld. Some jobs require argon pools to protect parts for oxidation, while pipes may need a gas purging setup. This adds to the skills welders need to learn to be effective at using this technique.

Which Type of Welding is Best for Small Spaces?

The wire feed adds bulk to the gun on a MIG welder. TIG welders only need to transfer electricity to the electrode, making them thinner. Some TIG torches have a bendable tip, so they can get into tight spaces that are unreachable with other welding methods.

Which Type of Welding is Better for Large Jobs?

Since the electrode is always moving, guns on MIG welders heat up slower than TIG torches. This lets users weld for longer before taking a break to cool the gun. However, both MIG and TIG welders are available with water cooling, which controls temperatures during long welding jobs.
 
With both methods, the limiting factor is often the duty cycle of the welder, not the handle. Even industrial grade welders need time to cool down between welds.

Where are TIG and MIG Welding Used?

MIG welding is used where speed is important, and in less than ideal conditions for both climate and metal quality. TIG welding is used where weld penetration is critical, exotic materials are involved, or space is limited.