Similarly Different: Flux MIG Welder Mix-Ups Explained

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Welding Buddy Experts

July 22, 2021
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When you search “flux-cored welding,” some results that come up are about metal inert gas (MIG) welding. You get confused, wondering if they’re the same thing or two different things combined.

Here’s a brief answer: they have similarities, but significant differences determine the welding process you should use. 

If the term MIG flux welder or flux MIG welder is still confusing for you, this is the right article to help you better understand flux-cored arc welding (FCAW) and MIG welding. We’re breaking down what gets these two mixed up together and what their essential differences are.

Before you decide what type of welder you’re going to use for your next workpiece, sit down for a few minutes and add this to your welding knowledge!

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Flux-Cored Welding vs. MIG Welding

Below are the basic definitions of FCAW and MIG welding, followed by a breakdown of their similarities and differences.

FCAW is an automatic arc welding process that uses a machine to feed an electrode to the weld joint. Tubular electrodes are used for this welding method and are filled with flux, a purifying agent used to join metals and protect the weld against contamination. FCAW also has two types: gas-shielded and self-shielded welding.

On the other hand, MIG welding is an arc welding process that joins two metals using a heated wire electrode (solid or cored) continuously fed into the weld pool. Additionally, a welding gun provides the shielding gas that protects the weld pool from air contamination.  


What are the characteristics that get FCAW and MIG mixed up? Check out the critical points below.

Type of Welding Procedure

Both FCAW and MIG are electrical welding methods and use a wire electrode to form a welding arc. Current will pass through the electrode and cause the arc to heat up, creating a weld joint.

Material Used to Weld

Both welding methods use a spool of wire as an electrode to weld. The wire will deliver the filler metal (heated and melted metals that create the weld joint) to your weld.

Shielding Gas Generation

Air substances such as oxygen, nitrogen, and hydrogen create porosity and excessive spattering when welding. To counteract these issues, MIG welding and FCAW use shielding gas to prevent exposure of the molten weld pool to air substances.


Reduce some of your confusion with these significant differences between flux-cored and MIG welding.

Key Feature: The Wire Type

While both welding processes use a spool of wire, the type of wire is where the difference lies. You use a solid wire in MIG welding, while the flux wire welder is filled with flux and is hollowed out.

Use of Protective Gas

The use of shielding gas is also different between MIG and FCAW.

In MIG welding, you need an external high-pressure gas container (with a flow meter) that connects to your MIG welding machine through a hose. You can use several gasses for MIG welding: argon gas, carbon dioxide, or a mixture of the two. A tri-mix type of welding gas consisting of argon, carbon dioxide, and helium is also an option.

FCAW uses melting flux material in the wire to generate the shielding gas. As briefly mentioned earlier, FCAW has two types: self-shielding and gas-shielding. Self-shielding generates the gas from the flux at the weld point, while gas-shielding involves an external gas (tubular wire with flux). You can use carbon dioxide, argon, or a mix of the two for FCAW.

Weld Polarity

Polarity in welding is the positive or negative terminal setting in the electrical circuit that forms when a welding machine turns on. It is a crucial part of the setup because it directly affects the welding strength and quality.

MIG welding uses direct current electrode positive, and FCAW uses direct current electrode negative.

Which Is Better?

Another commonly asked question when comparing two things is: which one is better? Welding methods vary in strength and weakness. Rather than looking for a simple answer, it’s more important to look at these two aspects that can influence your buying decision: pricing and qualities.


A tricky part of FCAW creates a misconception on which one is cheaper than the other: the flux-cored welding wire. In stores like Amazon, the price of flux-cored wires can go up to $70, while MIG solid wires are around $20–$40. Therefore, FCAW seems more expensive than MIG.

However, if you include the overall costs of the welding machine, MIG welding is more costly because it needs additional equipment. One example is the external tank used for the shielding gas, which is only optional in an FCAW machine.

Identifying Strengths and Weaknesses

Another way to make the buying decision easier is to identify the strengths and weaknesses of each machine. No machine is without any shortcomings, so ensure that you look for these things when choosing between FCAW and MIG welding.

Below are the pros and cons of the two methods.

Welding Type
 MIG   ● Works for indoor welding ● Generates less spatter ● Easy setup ● User-friendly and convenient for starters ● Low maintenance requirements  ● Not a good welding method for thick materials ● Additional charges needed for equipment to complete setup
 FCAW  ● Works for outdoor welding ● Requires less equipment ● External shielding gas is optional ● Cheaper than MIG welding  ● Not a good welding method for thin materials ● Welding gun positioning is tricky for beginners
flux mig welder man woman talking

Tips in Choosing the Right Welding Technique

Now that you know the essential similarities and differences between FCAW and MIG welding, you must understand the welding technique you want to use. But if you are still unsure, here are a few considerations to review.

What Material Are You Welding?

First things first: what are you going to weld? Familiarize yourself with the right welding process for each type of material.

Steel is the only metal you can weld using any welding method. Other materials such as aluminum alloys, titanium, copper, cast iron, and brass fit only one or two methods.

Additionally, identify how thick or thin the metal is. MIG welding works best on thin to medium (3/8-inch) materials, while FCAW works well on thicker (at least 3/4-inch) materials.

How Much Time Do You Need?

Generally, MIG welding is the fastest method, but you can do quick welds using stick or tungsten inert gas welding.

Identifying which welding method is the quickest or slowest depends on the material, welding project, and environment you are working in. Make sure to seek the help of a welding expert or get some ideas from thorough research.

How Much Is Your Budget?

How much are you willing to spend? The answer depends on your specific welding needs, so make sure to list down these specifications: power requirements, amperage, duty cycle, project goals, safety equipment, and extra accessories. Then, look for a unit that matches these needs.

Final Thoughts

FCAW and MIG often overlap because some machines work well on both processes. However, the advantage of knowing their significant differences is that you can choose a welder designed to work specifically on the type of project you’re working on, producing much better results.

We hope that this article has helped you get a better understanding of the MIG flux welder confusion.

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