What is Flux Core Welding & How To

Did you know that there are different types of welding for you to choose from, the same way there are different plasma cutters?

Many novices are surprised by this fact. They thought that all welding was the same, not realizing that their differences lie in the small details. And for those who want to learn how to do it, it can be overwhelming.

So if you want to learn, where do you even start? What type should you study first?

Many pros would say that MIG is the easiest to learn and is most suitable for beginners. But others claim flux core welding or gasless MIG is better because the learning curve is much easier. That is, even compared to the traditional way.


Flux core welding is a semi-automatic arc welding process that is great for thicker metals. The easiest way to do flux core welding is with the pull technique. The most essential tips for flux core welding is to maintain proper drag angle and avoid burnback.

Continue reading

If you plan to do your work outdoors and can’t be bothered with the necessary prep work in most types, then flux core is right for you.

Don’t know how to do it? We’ve got you covered, although you will need to practice.

flux core welding

This article will explain what flux core is and how to do it. We’ll also include some important tips to help you master it.

Curious to check out some of the products we have available? We carry everything from waste oil furnaces to pond aerators.

Table of Contents

What is flux core welding?

First, you need to know what exactly flux core welding is. How is it different from other types, particularly MIG?

Also referred to as FCAW, the flux core arc welding process is one of the types that involves creating an electric welding arc and the use of a wire spool that acts as the filler metal. Because this wire is directly attached, it is constantly being fed to the gun when in operation.

The process starts with creating an electric current when the base metal and wire meet while the equipment is in operation. Once they separate, a resulting electric arc is hot enough to melt the wire and partially melt the base metal fully. This now creates a molten pool of welding wire and metals. When this pool cools down, it solidifies. This forms the weld joint.

Flux core requires minimal equipment and tools. You’ll need your chosen equipment with the gun attached and your workpiece. You’ll also need the right wire. This is generally much simpler than the setup required in other machines, specifically the more popular TIG and MIG ones.

Here’s a list of the most common types:

  • SMAW
  • FCAW

How to flux core weld

Here’s a quick guide on how to flux core weld.

How to use a flux core welder

  1. Before firing up the welder, make sure to get comfortable in your workspace.

  2. Check if the equipment is tightly plugged in, leaving no room for loose ends.

  3. Set the electrode polarity to DC electrode negative or straight polarity.

  4. Make sure you’re using the correct drive rolls.

  5. Ensure that the wire tension is ideal, not too much or too little.

  6. Examine the consumables and replace any worn-out contact tips and liners.

  7. Select a wire that works for your material’s thickness.

  8. Adjust the voltage and amperage settings to match your metal.

  9. Determine the ideal wire stick-out. Typically it’s about ¾ inch.

  10. Make sure the angle and positioning of the welding gun are comfortable.

Flux Core vs. MIG: Are They the Same or Is One Better Than the Other?

Here’s a look at the advantages and disadvantages.

Suppose you already have some background in welding, particularly in MIG. You may have noticed that flux core shares some similarities. After all, they both involve a wire directly fed to the welder. However, certain conditions lend itself better to others.

Its entire process is a lot like MIG, so they are often confused.

Are flux core and MIG just the same? If not, which one is better?

The answers to those questions depend mainly on one thing: the shielding gas, with carbon dioxide being the most common, to offer protection for the weld pool and avoid porosity.

Did you notice that this gas was never mentioned when we discussed flux core? That is because this is where the difference between the two becomes obvious.

MIG is also known as metal inert gas welding and gas metal arc welding (GMAW). It involves continuous flux core wire feeding. However, it requires a shielding gas that will protect the welded area from contamination. This shielding gas is also continuously being released simultaneously as the wire.

You might think that having a shielding gas is better, so why bother with flux core? While it does not use a separate shielding gas, its alternative serves the same function.

The wire used in flux core has a hollow center filled with flux, unlike the solid wire used in MIG. As this wire melts, it creates its version of the shielding gas to protect the weld metals from contamination while working. Flux core also tends to create more spoke during the welding processes, one of the reasons some may not like it.

Both MIG and flux core have components that prevent the contamination of the metals while working on them. They do it differently. MIG requires using a separate tank for the welding gas connected to the welder, but the flux core does not.

It is the main difference between the two. But because of their similarities, some MIG and flux core welders allow you to do both types using a single machine.

There are also other noteworthy differences between the two, such as:

  • MIG is limited to working on thin metals or those of medium thickness. In contrast, flux core can work with thicker materials.
  • FCAW allows you to work faster than MIG, which means you can do more with it.
  • MIG creates a neater-looking bond and beads. Flux core can get porous and create “wormholes.”
  • Fumes and spatter are more often present in FCAW than in MIG.
  • The shielding gas used in MIG makes it suitable for indoor use only. FCAW allows you to work both indoors and outdoors.
  • While the process generally involves preparing the base metals before starting, FCAW is more forgiving in that aspect. The wires used in FCAW contain de-oxidizing elements. It makes it capable of bonding materials even with rust and oil present. You may also be able to work on pieces with other contaminants present.
  • The overall cost ends up cheaper when MIG welding is used. The wire used in FCAW is more expensive than the solid wire in MIG.
  • MIG has deeper penetration, while it is rounder in FCAW and requires you to remove the slag present afterward.

If you were to pit flux core versus MIG to know which one is better, you would not get a straight answer. Both have their advantages in specific situations. That is why we cannot judge if one is better overall.

But if strength is your primary concern, don’t worry because they are equal in that aspect.

What Is It Used For?

Because of its similarities with MIG, people assume that flux core can also be used for the same applications. While they can often be used interchangeably, FCAW is more often used for industrial applications.

It is more cost-efficient because it can be done automatically or semi-automatically. It welds much faster have better penetration on thicker metals. Nickel-based and iron alloys and structural steel are examples of such. They do not require a thorough cleaning before you can start.

While it involves using a more expensive wire, FCAW also allows various industries to cut costs. It’s the case, especially if plenty of welding is needed.

Some of its common applications include:

  • Shipbuilding and other shipyard-related applications
  • Underwater
  • General repairs
  • Manufacturing
  • Pipelines
  • For indoor and outdoor purposes, including in a windy environment
  • Agriculture, such as those involving farming equipment
  • Automobiles
  • Metals with dirty surfaces, especially those that can no longer be easily cleaned
  • Anything involving mild steel
  • The pull technique involves pointing at the weld puddle as you drag away from the metal. It’s great for deeper penetration.

You can use flux core for various metals with varying thicknesses. It is recommended that you use it on metals with a minimum thickness of 20 gauge. But you plan to weld on thinner materials. You will get better results through MIG and the appearance and quality it provides, while avoiding problems.

Welding TypeBest Use
Flux CoreOutdoor use, heavy gauge steel, and dirty or rusty metal
TIGThin gauge materials, precision welding, and stainless steel or aluminum
MIGIt’s often used for general fabrication, auto body repair, and welding mild steel.

How to do it


If you consider yourself a novice, learning how to flux core weld is one of the essentials you should know first. Both manufacturers and seasoned pros claim that mastering it will only take you about an hour on average. And once you master it, you can easily move on to learning the other types.

Flux core does not involve complicated steps, but what is important is to set up your equipment properly. After that, it is a point-and-shoot process. If MIG is called the “hot glue gun” of welding, you can also think of flux core as such.

The general process semi-automatically involves the following:

  1. Once you set up your equipment, you may opt to clean first the surfaces of your base metals. Make sure the appropriate wires are connected.
  2. Secure the materials using clamps or anything similar.
  3. Switch on the machine and adjust it to the recommended settings, depending on your materials. Most equipments come with a chart that you can use as your reference.
  4. Squeeze the trigger to start. The speed of travel will depend on the material being worked on.

But when it comes to automatic flux core, the machine will do everything for you. You only need to monitor its operation.


Flux core can be done in all positions, but specific techniques are also recommended for specific purposes and situations. In particular, there are four techniques available: forehand, backhand, weave bead, and stringer bead.

ForehandBackhandWeave Bead
Stringer Bead  

Also, make sure to always consider the power source and wear safety glasses.

Forehand Technique

It is typically used for thin materials. The forehand technique involves moving the electrode over the site following the welding direction as if you are pushing it away. While it can be used in horizontal and flat positions, it is ideal for overhead fillet and vertical up welding positions. Splatter is quite common. You can lessen it by using the right travel angle.

This technique also gives you a better view of the molten pool created and the joint itself. It makes it easier for you to do the work. If you are using a flux core arc machine that is gas-shielded, this is the technique that you should use.

Backhand Technique

In contrast, the backhand technique is similar to the stick method. It requires moving the electrode along the welding site but in the opposite direction. Also known as the drag technique, this is the most popular FCAW technique and is used if you require a deeper penetration.

You can only use this technique in the 4g, horizontal, and flat positions. And if you want to minimize spatter, use this technique in the 4g position. The molten pool is not as visible with this technique since you are making a pulling motion.

Weave Bead Technique

Traditional techniques involve traveling on a straight path. In the weave bead technique, you create the beads zig-zag direction. This technique is rarely used in FCAW, but it is done in a vertical position only when used.

Stringer Bead Technique

For the stringer bead technique, beads are made following a straight line. It requires faster travel to lessen the heat input on the base metals. Another commonly used FCAW technique can also be done in any position.

Note that these four techniques are easy to learn, even for beginners.

Sheet Metal with Flux Core

Sheet metal may be one of the more complicated materials to work on, but it is possible with flux core. However, it isn’t very easy to do so because it is heat-sensitive. You need to have adequate heat control, which is hard to achieve with FCAW.

Welding sheet metal via flux core is doable and follows usual procedures. But because it is more suitable for thicker materials, you typically need to start with the lowest settings available.

It may be hard to get the right settings in one go. Do a test first on scrap sheet metals before starting the actual workpieces.

Once the sheet metal becomes warped or distorted, it will be very difficult and time-consuming to remedy the issue. It can easily happen when using the wrong settings. That is why you need to prevent it from happening in the first place.

Flux Core & Aluminum

Aluminum is another material that can be a challenge to work with. This is because it has properties that make it complicated to weld using any type.

It involves using a wire that matches or at least closely resembles the base material. If you plan to weld aluminum via FCAW, this means you need to use an aluminum wire.

But does that even exist? No.

Simply put, you cannot weld aluminum using FCAW. But if you need to do so, you need to use other types. You’ll need to right welding process to proceed, which usually includes working with argon.

Welding MethodCostDurabilityFinish
Flux CoreLowMediumRough
TIGHighHighestVery Smooth


Are Flux Core welders any good?

Flux Core welders are ideal for welding thicker joints as it offers greater penetration. It’s especially suited for industrial use or heavy manufacturing.

What should I look for in a flux core welder?

Before investing in a flux core welder, you need to ensure it provides a good value for money. Check the welder’s current output and if you can weld thicker materials using it. For greater precision and accuracy, study the controls offered.

Is stick welding better than flux core?

Stick welding supports a greater range of metals, including magnetized metals. As a result, their electrodes are better suited for deeper penetrations and fusing dirty metals. However, the deposition rate and efficiency are higher with flux core welding. It also drastically reduces the risk of metal warping or distortion.

Is flux-core welding as strong as MIG?

Flux-core and MIG welding have similar strengths, so neither typically stands out. In the case of cast iron, flux-core welding has the upper hand. It allows for deeper penetration. Therefore, it’s stronger welding.

Are you just getting started?

Suppose you are just getting started or haven’t even gotten started yet. It is no wonder you may be overwhelmed by everything you are learning. 

In this article, we touched on several different topics. There is no doubt you can make a mistake you would regret if you buy a welder you don’t feel is right.

Suppose you hope to open a shop and earn money off the things you are producing. The chances are you won’t be able to achieve that goal with a piece of welding equipment as simple as a flux core welder. You will quickly find yourself needing something a little more robust. Perhaps you need one of the lower-level multi-process welders that we have.

Figure out how to buy the type of equipment that will be able to do what you want to get done. Do you believe that the flux core machine will be too limiting?

You need to make up your mind about some important things. Are you going to want to weld other types of surfaces in the future?

When buying this type of equipment, it is not like you are buying an engine-driven welder. An engine-driven welder will set you back many thousands of dollars. For some people, it makes more sense to buy a cheaper welding machine now and upgrade later. Thousands of dollars is a substantial investment you may not be ready for. 

The question may be whether or not skipping the step of buying a flux core welder isn’t beneficial. It does have some advantages. It may require less precleaning of metals than in other scenarios. There isn’t a need for a welding gas, which provides a shield against components that could enter the weld and weaken it. 

Flux core may work with about the same types of metals that MIG can. Some of them include mild and low alloy steels. It’ll also work on stainless steel and some nickel alloys. However, it will severely miss out when compared to something like TIG.

Have you found out which of these options is best for you?

  • FCAW
  • SMAW
  • TIG
  • MIG

We will be happy to hear your thoughts

Leave a reply

Passion Plans
Login/Register access is temporary disabled