Different Types of MIG Welding Wire – What You Should Know

Jan 22, 2021

MIG welding wire consists of a spooled-up electrode that’s fed through a MIG welding “gun” and is heated to melt metal and join workpieces together. Sounds simple enough, right?

Well, it’s not quite that easy. There are a lot of different types of MIG welding wire, and in this article, we’ll explain some of the differences between them, what to consider when choosing welding wire, and the importance of choosing high-quality wire.

Flux-Core vs. Solid MIG Welding Wire

There are two primary types of MIG welding wire – flux-core and solid MIG welding wire.

Flux-core wire is a metal electrode that contains a “flux compound” inside the electrode. When the wire melts and reacts with the welding arc, this forms a gas that protects the weld from oxygen, which can cause defects in the weld. This means that no shielding gas is required for this type of wire – though in some cases, shielding gas may be used alongside flux-core wire for even more protection.

In contrast, solid wire electrodes are exactly what they sound like – large reels of solid metal wire that do not contain any flux. This means they must be used with a shielding gas. The most common shielding gas is 75% argon and 25% carbon dioxide. The welding gun delivers a steady stream of gas from a container, which surrounds the electrode and weld area to prevent oxidation and defects in the weld.

Depending on the application, both kinds of MIG welding wire (solid and flux-core) can be made from a variety of materials including aluminum, stainless steel, copper, and silver, to name just a few.

Considerations When Choosing MIG Welding Wire

Wondering what you should think about when you choose MIG welding wire? Neither type is superior compared to the other – rather, the right choice depends on your situation and preferences. Here are a few things to keep in mind when you pick MIG welding wire.

  • Desired weld cleanliness – As a rule, solid MIG welding wires used with shielding gases produce a cleaner weld with much less spatter compared to flux-cored wire. Spatter does not necessarily affect weld quality, but it may require additional grinding, polishing and finishing to remove it before painting or other such surface preparations, so solid wire is more commonly used in these situations.
  • Workpiece material – Different types of wire are used for different materials. ER70S-3 wire is often used for mild steel that’s clean, oil-free, and rust-free, while ER70S-6 contains a deoxidizer and is used for mild steel that’s contaminated with corrosion or mill scale.
  • Environment – In very windy or challenging outdoor environments, flux-core wire is usually a better option. The gas used to shield solid MIG welding wire may be blown away while welding in windy conditions, so unless a wind screen is used, this results in a lower-quality weld. Since flux-core wire contains gases that emerge when it’s heated, the metal is shielded more effectively in those conditions.
  • Wire thickness – As a rule, thicker wire is recommended for thicker workpieces. 035-inch diameter wire is the standard used for most welds, but it may not be adequate for very thick pieces of metal. Multiple passes may be required to create a strong weld.
  • Weld unit power – This is closely related to wire thickness. The higher the voltage and power of a MIG welding unit, the higher thickness it can accommodate. Using a thicker wire is not a good idea with lower-powered MIG welding units. The lower overall amperage and output may result in a failure to melt the workpieces properly and create a quality weld. Always consult the manufacturer’s instructions to see the maximum recommended wire thickness.

No matter what type of MIG welding wire you buy, you should always make sure to invest in high-quality wire. Compared to lower-quality welding wire, quality MIG wire is more forgiving, can produce a more sound weld even in less-than-perfect conditions, and still represents only a fraction of the overall cost of welding.

Need Help Finding the Right MIG Welding Wire? Contact Vern Lewis Welding Supply

Vern Lewis Welding Supply has a wide variety of MIG welding wire and MIG welding gases. Whether you’re welding steel, aluminum, copper, or any other material, we can provide you with the welding wire and gases you need to get the job done.

Need help choosing the right products? Contact us with more information about your job and your situation, and our team of experts would be happy to help out.

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