Both Metal Inert Gas (MIG) and Tungsten Inert Gas (TIG) welding rely on electrical current to raise the temperature of the weld area, but the main difference between the two is that a MIG welder uses a consumable electrode while a TIG welder uses a separate, non-consumable electrode.
The following are some of the main differences between the two, as well as how each one is used.
How Do MIG and TIG Welding Work?
Welding is the process of joining two pieces of material, usually metal, by using pressure, heat, and filler metal. MIG welding and TIG welding are two different methods that each have merit in various project types.
MIG welding uses an electric arc to make the weld, feeding a metal wire through the gun that is ignited and liquified, joining the two project pieces together.
The filler material runs through both the liquified metal and the torch generating the heat. Since welding through an electric arc requires the user to hold the filler material and torch separately, TIG welding is generally considered the more difficult of the two methods.
In layman’s terms, a MIG weld has a continuous machine-fed wire that is melted as it exits the welding gun, while a TIG requires the user to melt the joined piece as it passes into the electric arc.
Electrode Use
The most readily noticeable difference between MIG and TIG welding is the use of a wire electrode in MIG welding. This wire is continuously fed to facilitate the joining of the two pieces being welded.
TIG, on the other hand, relies on a non-consumable tungsten electrode inside the welding gun with a separate handheld welding rod that the operator holds in their other hand. Touching the rod to the electrical arc causes it to melt, creating the molten weld pool that cools into a successful weld metal.
Inert Gasses
Both MIG and TIG welding rely on inert gasses to shield the electric arc from outside contaminants. Without it, trapped gasses in the weld can cause porosity, which will weaken the weld over time, potentially leading to a collapse.
Both welding methods rely on a separate reserve tank of inert gasses that are fed at a continuous rate to shield the electrical arc zone from becoming contaminated, hence being called shielding gas.
The particular gas used, however, varies between the two. TIG welding generally relies on pure argon or a blend of argon and another non-reactive shielding gas like nitrogen or helium to avoid the risk of contamination.
MIG welding, in contrast, uses a mixture of argon and carbon dioxide, since it offers better penetration that caters to the type of jobs MIG welding is designed for.
These gasses are also expelled at different rates, with a MIG welder maintaining a flow of 35-50 cubic feet per hour. A TIG welder, on the other hand, expels a gas flow of 15-25 cubic feet per hour.
Electric Current
The electric arc produced that causes the metal to liquify can be different depending on whether you’re using a MIG or TIG welding gun. A MIG welder always uses a DC current, which is preferable for this welding method since it provides consistent voltage and offers better penetration of the metals.
A TIG welder has more versatility, allowing AC and DC power sources. As a result, TIG welders can manipulate the electric arc to suit the thickness and type of metal they are working with, as well as the amount of spatter in the weld pool. TIG welders can directly control the amount of electricity in the torch using a foot pedal, reducing the problem of arc instability.
When Is MIG or TIG Welding Used?
Each method of welding is noticeably different, and each has its uses depending on the thickness of the metal, the material being welded, and the amount of penetration needed. MIG welding is more user-friendly and less resource intensive, allowing for a quicker weld in most cases.
As such, it’s often used in a factory construction environment where a single machine operator can use a MIG welder such as the Lincoln 210 MP welder to combine project pieces quickly and efficiently.
On the other hand, TIG welding is used for projects where the aesthetic is more important—not that MIG welding can’t be done neatly. It’s just much harder. TIG welding allows for narrower beads of molten metal and more precise control of the electric arc, generally allowing for a more accurate weld despite having a sharper learning curve.
Speed and Precision
TIG welding also generally sees use in projects where quality is more important, although the difference is less a matter of weld design and more a matter of human error.
MIG welding is ideal for creating a semi-automatic process, producing hard and fast weld joints with deep penetration. The process is pretty fast, given that the wire is fed through at a constant rate, allowing the operator to maintain speed.
TIG welding requires the operator to take their time a lot more. This extra time allows the operator to focus on what they are doing and limits human error.
The result—a cleaner, more precise, and generally stronger weld between the two project pieces.
Precise and slow welding is something that MIG welding just cannot do consistently, given that wire burn back and arc instability both contribute heavily to lower-quality outcomes in weld projects that used MIG welding guns.
Thin projects or pieces with delicate edges are more in line with TIG welding, since it is slower, more durable, and creates a cleaner finish.
The Bottom Line
MIG welding and TIG welding both create a molten weld pool using an electric arc, shielded by an inert gas that prevents contamination. The main difference between the two is that MIG welding uses a single machine-fed wire designed for speed and deep penetration, while a TIG welding gun requires the operator to hold the filler metal independently.