MIG Vs Flux Core Welding: Main Difference, When to Use Them

mig vs flux core welding

MIG welding vs. flux core welding, two different techniques for joining two metals. MIG is a more advanced form of welding that uses a wire to create the weld, while flux core is also an arc type but instead uses a metal rod as its filler material. 

This article will discuss the pros and cons of each type and which one would be better suited for certain jobs.

MIG Vs. Flux Core Welding

Deciding to use Flux Core welding rather than MIG depends on:

  • What you are welding
  • Where you are

It also comes down to personal preferences regarding the finish of your weld after that point.

Some key points and differences include walking through them one by one to understand when choosing between these two types of methods used while doing manual work with metal materials together as a team effort while trying not to hurt yourself too badly.

Some people prefer flux-core welding, while others swear by MIG.

Everyone has a reason for choosing what they do, but it’s hard to say which is better overall.

What Is Flux Core Welding?

Flux core welding is a process denoted by FCAW (Flux Core Arc Welding).

It’s an early welding technique and only used in the flux welder, which can also use a MIG set to feed shielding gas or solid gases.

The flux core provides a shield from any of the surrounding atmospheres.

Still, it has more impurities than other methods, so proper monitoring systems at hand must be done carefully, and training for each operator.

What Is MIG Welding?

A wire electrode connects two metals in MIG welding as they pass through the welding gun.

Inert gas keeps off airborne contaminants from the weld area, making it ideal for non-ferrous and aluminum materials.

Main Difference

The main difference between flux-cored arc welding and MIG welding is how each process shields itself from oxygen.

FCAW gets its shielding from a hollow wire containing flux, similar to “pixy sticks” candy.

This allows operators to weld outdoors where it can be windy.

It’s like an outer coating for SMAW (stick) electrode!

For MIG, there are two options: either using argon gas or adding another filler metal in the form of short rods, which we will call stick electrodes.

These metals melt at much lower temperatures than steel, so they do not affect base materials when used properly.

Both of these welding processes will give you excellent grounding. But, some differences might come up when doing one over the other.

Use of Shielding Gas

When comparing the two welding processes, one difference you will come across is that shielding gas is necessary when using a MIG wire.

This means purchasing a separate pressure tank connected to either flow meter or regulator, attached via a running hose.

The hose supplies the welder with its respective gas, and there are several gases used for protection in MIG welding: argon, carbon dioxide (CO2),

more commonly called “shielding” and mixtures of Argon/CO2 or Ar/CO2/He can all work depending on what type of metal(s) is being welded; stainless steel uses mainly helium mixed with some CO2 & Argon.

When it comes to flux core welding, you will find two types of wire:

  • Self shield
  • Dual shield 

In contrast with what is used in MIG welding, where shielding gas must be transported everywhere for proper utilization, the self-shield produces its protection gases at the point of welds.

However, the key aspect here is that this type requires less money since there are no additional costs involved compared to other processes such as TIG or stick, which require heavier equipment like tanks, etcetera!

When using these wires together with another process, one needs good practice.

If not done properly, they can actually cause more harm than good due to low-quality materials being used. So careful consideration before deciding on any procedure would definitely serve better results.

The Kind of Wire to Use

Among the main differences, this one is important to note.

The MIG welding process uses a solid wire electrode, while flux core (FC) uses tubular welding wires made of metal on the outside and flux at the center.

The difference between these two options means they act differently in different situations. Since FC wires are hollow with high-temperature materials inside them, their use requires special precautions when not used near flammable substances or gases.

Whereas because SFE electrodes have no shield gas protection built into them, which increases operator risk due to poor visibility under normal conditions,

it makes it easy for an operators’ protective clothing to become contaminated by arc radiation, therefore, exposing him/her to dangerous ultraviolet light that might cause skin damage.

Comparing The Weld Polarity

When doing MIG welding, you need to attach a ground clamp directly to the positive terminal. If it’s a self-shielded flux core wire, then it’s best for this type of work if we use DCEN settings, and since one side needs are weld with the negative electrode, all components should also have the same polarity as well such as a torch, etc.…

Each process must fit with the right applicable wire starting from setting: In-depth, self-shielded flux requires DCEP (direct current electrode positive) while inert metal gas uses GMAW (gas metal arc welding). This means attaching a direct cable on the frame or clamped into a table.

The setup may differ whether you’re welding stainless steel or gas-shielded flux-core wire with a DCEP polarity.

Gas shielded requires additional shielding gas for its specialized process of using self-shielded doesn’t require it but needs settings that allow users to switch between DCEN and DCEP polarities.

Does Flux Core Offer Better Metal Penetration Than MIG?

Two main factors will determine how deep your welding penetrates the metal: voltage and thickness of the material.

A thicker piece of metal means a higher resistance to electricity, which is why you’ll need more voltage for it to be successfully penetrated by electrode arcs or filler rods.

Using flux-core wire instead of MIG will affect penetration less than using a thinner steel sheet because there’s no spool gun needed with this type of machine; therefore, not drain as much amperage from your welder while still achieving high-quality welds due to its short heating time per pass.

For example, you can weld a 4.8mm steel using a .030 flux core wire with 140v. This is different from the results of solid MIG wire, which will give you 1/8 inch welding on the steel of this diameter.

The same principle applies to other materials like Hobart, Lincoln, or Everlast; however, if done in Flux Core mode, it would be better since thicker material could be weaved and less amperage used to use MIG (solid) wires when doing such an activity.

Welding Quality: Flux Core Weld Vs. MIG

In terms of quality, MIG welding is considered to offer better results as it makes the joint stronger and produces a smooth finish. Depending on what you consider ‘quality, in this case, both methods have their own strengths, which will determine if either process is the best option for your project or not.

Slag and Spatter Produced

The outcome of MIG and Flux Core welding varies when we consider the amount of slag produced.

There can be a lot of spatter during welding in flux core because there’s an impurity at its center called “flux.”

This creates some kind of pool that will later need scrubbing once cooled down; however, this isn’t always guaranteed for both types since even Mig produces residue every now and then.

There are different results regarding how much slag and spatter is produced with either MIG or Flux Core wire: For example, while using the former one (MIG), you might find out that sometimes no new metal needs cleaning after cooling.

Carbon dioxide shielding gas produces more spatter, which can easily be removed by anti-spatter products. Flux core welding is said to generate more spatter than Argon/CO2 mixture or argon alone due to its high hydrogen content and a tendency for intergranular melting.

When to Use Them


Appearance is an important element. When working on materials less than 3/16-inch thick, down to thin sheet metal (24 gauge), the solid wire will produce a clean-looking weld.

For example, a short-circuit transfer with .030 inch diameter and 18 – 19 volts set at 160 – 170 amps using 75% argon gas for shielding would usually create little spatter while reducing the chances of burn throughs or heat affected areas.


In windy locations, solid or gas-shielded flux-cored wire is more difficult to use because exposing the shielding gas can compromise the weld integrity. Typically, the loss of shielding gas will produce porosity visible in a distinctively white area at and near where it was lost (the “blow hole”).

On the other hand, self-shielded, flux-cored works well for welding outdoors with an easily adjustable spool gun, making it easier than ever before!

Welding wire thickness is one of the most important variables to consider when choosing a shielding gas.

Thickness, Parameter Settings, and Type of Application

Thicker material needs to be given to the output power source and the diameter of the welding wire being used.

A novice welder might not know this, but they are best off using .035-inch-diameter solid wires for thinner applications where speed matters more than penetration or strength.

These combinations produce higher speeds with less spatter at lower amperages work better on thin materials like sheet metal. In contrast, thick materials such as heavy plate steel will require additional input from an AC balance control (to offset DCEP effects) or pulse settings on DCEN equipment.

It is important to use the proper welding wire for thicker materials. Using a solid wire that’s too fine can decrease penetration and require multiple passes, increasing time spent on the project.

Advantages and Disadvantages

There’s no “winner” between solid and flux-cored welding wire. They’re simply different, so they each have their own benefits depending on the type of application you want to use them for.

Solid wires usually result in deep penetration into your metal along with little spatter–however it has a smaller ball transfer than its counterpart (flux-cored), which produces low levels of spatter throughout the process and produces rounder profiles that create excellent sidewall fusion!

Which One To Choose As a Beginner

If you’re not familiar with welding, a flux core welder is the best way to go.

These welders are easy for beginners and popular among auto body shops because of their versatility in materials that can be used.


When choosing between MIG or Flux Core Welding, it is important to evaluate your needs first.

Think of what metal you will weld, what you would like the results, and how much money will go into buying a machine setup.

Whatever process you choose for welding metals together in various applications or conditions should have specifications that make them suited differently depending on different requirements from customers,

such as environment and budget they can afford per unit sold at market price, which varies per set up configuration quality level machines needed by an average customer who wants good enough service lifetime warranty products

with high-performance ratings often come expensive compared with cheap ones made for entry-level users only but ideal when one does not need heavy-duty machinery.

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