How to Know When to Use MIG vs. TIG Welding

In Welding

Marlin Steel on July 24, 2018

This robotic welder can alternate between MIG and TIG welding with ease.For all of Marlin’s custom wire baskets, welding is crucial for ensuring that the basket is able to meet the customer’s needs. However, there’s more to welding than just heating and fusing the metal wires of the basket. There are many different specific welding techniques that can be used for a given metal form.

Using the right kind of welding technique helps ensure that a wire basket is able to hold together under stress. Using the wrong kind of welding technique, however, can lead to numerous problems, such as weaker bonds, corrosion of the weld joint, or failing to complete the weld in the first place.

Two of the most common welding technologies used in factories across the U.S. are metal inert gas (MIG) and tungsten inert gas (TIG) welding. Both of these arc welding techniques have their similarities, but there are times where one might be more useful than the other. So, how can you know when to use MIG welding or TIG welding?

Explaining the Difference Between MIG and TIG Welding

Both MIG and TIG welding are arc welding processes that use an inert gas, which explains their alternative names—gas metal arc welding (GMAW) and gas tungsten arc welding (GTAW).

The key difference between the two is that MIG welding uses a continuously-fed wire that also acts as a filler material, while TIG welding uses a non-consumable tungsten electrode. This makes it so that TIG welding has to make the objects being welded hot enough to form a bond, while MIG welding can join objects by using the melting electrode as a filler material.

Because it uses filler material, MIG welding often performs better for welding thicker objects, since it doesn’t have to heat the material all the way through to form a bond. Also, the use of filler material makes it relatively easier to control than TIG welding. While the filler material could allow for the use of MIG welding to join dissimilar metals, it’s generally recommended that you avoid joining dissimilar metals whenever possible.

TIG welding, on the other hand, can join objects without filler to create neater welds. However, TIG welding requires a great degree of precision to avoid over-heating the metal being welded (which could cause stress cracks and other weld issues). Thankfully, computer numerical control (CNC) systems create a degree of precision that makes achieving consistent results very easy with TIG welding.

When Should You Use MIG vs. TIG Welding

So, when should you use one of these two welding techniques over the other?

A basic rule of thumb when choosing between MIG and TIG welding is to consider the following:

  1. How thick are the two pieces of metal being joined? Thicker pieces of sheet metal are very difficult to weld by simply heating them up until they fuse—the thicker they are, the more energy it takes to heat them to the melting point and the less efficient TIG welding becomes. If metals are especially thick, then MIG welding may be more effective.
  2. What is the electrical conductivity of the metal being joined? Another variable to consider is how ductile the metal being joined is. The heat used to fuse metal in an electric arc welding process is generated by the metal’s inherent electrical resistance as the electric arc tries to pass through the weld site. If metal is highly ductile, it will take more time to heat up, which consumes more energy. Electrically-resistant metal will heat up faster, making it easier to weld without filler material.
  3. Am I welding dissimilar metals? While it isn’t usually a good idea to weld dissimilar metals since it could cause numerous issues (weak bonds, weld corrosion, etc.), there are times where it may be unavoidable. If two dissimilar metals are being welded, it’s usually better to use a weld technique that supplies a filler material to create a bond. However, this filler material needs to be carefully chosen.
  4. Is surface condition/smoothness important? Filler materials increase the risk of weld spatter being left on the surface of a workpiece, requiring extra work to smooth out if the elimination of surface flaws is important. Direct metal-to-metal welds sidestep this issue to create welds that are typically much cleaner than filler-dependent ones.

If you can answer these few questions, it’s usually easy to establish which metal arc welding process would be the best for a given task. However, even when the choice seems obvious, Marlin’s engineering team still double-checks their assumptions using virtual physics simulation software to verify that the welded joint will perform as expected.

Need help developing the perfect custom wire basket for your manufacturing application? Contact the experts at Marlin Steel for a consultation. Or, learn more about our welding equipment at the link below:

Marlin Steel Ideal Welding Machine

Author: Marlin Steel
Marlin Steel
Marlin Steel is a leading manufacturer of custom‐engineered products from steel wire and sheet metal. Its industrial material handling containers serve many industries including aerospace, defense, medical and automotive.

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