Flux Core Welding Tips | All You Need To Know for Perfect Welds

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 Some of the people you have talked to probably mentioned flux welding, but you're probably not exactly sure what it is. You’ve seen projects they’ve completed with flux core welds, and watched the fluidness of their flux core wire. Now, you’ve purchased a flux core welder but you need some flux core welding tips before you can start welding flux. 

This authoritative guide is comprised of the best flux core welding tips from the pros. When you finish reading, you will know how to get the very best out of your welding projects and soon people will be asking you about your welds. Than, all you need to do is grab one of the best flux core welders for your project!

What Is Flux Core Welding?

Flux Core Welding is an electric arc welding process that can be either automated or semi-automated and allows for greater weld penetration. It's not overly different from regular arc welding or even MIG welding. However, a core difference is the wire used has Flux in it (hence the name) which covers all of the weld. 

This improves the stability and strength of the weld, as it will cool down slower compared to other welding techniques. This technique has a lot of uses in manufacturing because of its great portability - the flux wire has its own shielding, which means you don't need a separate gas tank for flux core. Here is a video that will can help explain:

Flux Core Welding Tips to Weld Outdoors with Ease

A lot of people have been under the impression that stick welding is the only way to weld outdoors.  That’s no longer the case. You can successfully use flux welding outdoors as long as you’re careful and methodical. 

One of the things to worry about with outdoor welding is wind. A gust of wind can easily blow away the shielding you’ve set up over your weld. If that’s what you’re worried about you can use self-shielding processes or gasless welders

You should also take care in choosing your wire. Self-shielded flux core wires can avoid the traditional issues that come up with outdoor welds. These will allow uninterrupted workflow without having to change wires or have shielding blown away. 

First Things First: Flux Core Welding basics

Before you begin to weld, you need to be prepared. Welding can be extremely dangerous, so make sure to avoid fires and injury by preparing your workspace. Clear away any potential fire hazards and don’t practice in enclosed spaces where there is no ventilation. 

You should be wearing safety classes, a welding jacket, industrial grade helmet with auto-darkening features, welding gloves, a leather apron, uncuffed denim pants or workpants, and leather shoes or work boots. Everything you wear should be flame resistant. 

Metal Preparation

Flux core welding is great for beginners because it’s more tolerant. You won’t have to do as much extensive preparation to clean your surface from contaminates. That doesn’t make it okay to practice bad habits, though. You will always get a better and stronger weld by cleaning the surface area of your base metals. This will also prevent rusting and scaling from happening. 

Use a metal brush or a grinder when you work. You should also clean the part of your base metal where you plan to attach your clamp. Failing to do so will create a poor contact area and you will end up having resistance in your circuit that will inevitably end up with a bad quality weld. 

Another thing you will want to do for thick metals is bevel the edges. This will help create a complete fusion for your final welds. This is especially true when it comes to butt joints. This will reduce the thickness and let you get a strong initial weld into place that you can build upon without losing strength in your weld. 

Equipment Preparation

You also want to make sure your equipment is safe to use and ready to weld. Make sure that you check all of your cables. If they are fraying, loose, sparky, or otherwise problematic change them out for better ones. All your connections should be very tight. 

You also need to know what your polarity will be. For flux core welding projects, you need to use a DC electrode set to negative. This is known as straight polarity. These connections are on the inside of your machine by where the drive rolls. 

Speaking of drive rolls, it’s important that you use the correct ones for your project. Flux core wire is softer than other, more solid wires; so knurled drives are a great plan for these. They’ll provide the bite you need without deforming or compressing your wire. Don’t use standard drive rolls with flux core welding. 

You also want to make sure your wire tension is balanced. If you have too much tension or not enough tension on either one of the drive rolls or in the wire spool hub, then you will end up having problems with your wire feed. Make sure that your tension is adjusted according to your welder’s user manual. 

You also want to be aware of any consumables. Removing excess spatter from contact tips is going to help you operate more smoothly. If your contact tips are starting to show wear, change them out with new ones. The same applies to worn liners. If your wire is rusty, get rid of it. 

Wire Selection

If you’re using mild steel, then you want to use the E71T-11 flux core wire. It is versatile enough to function in any position. It comes in a huge range of sizes and shapes. It’s also great when it comes to providing exceptional welding characteristics on both thin and thick material. 

When it comes to your wire diameter, you probably want to sit around .030 inches in diameter. This is a versatile, general-purpose diameter for welding a large selection of different metals and thicknesses. If you’re welding with extremely thick material at higher overall heat levels, then go ahead and bump up to a .035 inch wire, but the maximum diameter is .045 inches for very powerful output welder ranges. 

Voltage and Amperage

The voltage and amperage required for your welding project depends heavily on your metal’s thickness, the configuration of your joints, the position you’re going to use to weld from, and your wire’s diameter. Grab a chart or find an online calculator to help you set the correct voltage and wire feed speed for your metal, wire thickness, and welder capacity.  From there, it will be easier to make small adjustments and fine tune your performance. 

Wire Stick-Out

The stick-out of a wire is the length of your unmelted electrode that extends from the tip of your contact tube outwards. It does not include your arc length. Flux core welding usually needs about ¾ of an inch for stick-out lengths. This is twice what typical MIG welding recommends for stick-out length. 

Push or Drag?

It’s always better to drag when it comes to flux core welding. Pushing the MIG frequently pushes slag into your weld puddle. This creates a very dirty weld.  Pulling (also called dragging) your torch through the joint will make sure your spatter lands on the competed weld, minimizing porosity issues. 

This technique is best utilized by pointing your welding gun’s tip backwards towards the weld pool then dragging it away from your completed weld. A common adage is, “If there’s slag, you should drag.”

Travel Angle

In welding, a travel angle is defined as the angle relative to your welding gun when your gun is held in a perpendicular position within the plane of your weld joint. IN normal welding conditions, for all positions, your travel angle should be somewhere between 5 and 15 degrees. If your angle exceeds 220 or 25 degrees, it will cause a ton of excess spatter, decrease your penetration, and create an unstable arc. 

Work Angle

Your work angle is the position of your welding gun relative to the plane of the welding joint. This angle will vary with every new welding position and each different joint configuration.

Flat Positions

For flat positions, or butt welds with a 180-degree joint, you should hold your gun at a 90-degree work angle. This angle should remain the same no matter what direction the work is being done from. Direct your fuller metal straight into your joint with a 5 to 15 degree travel angle using small, side-to-side motions. This helps to fill a large gap and allows for multiple passes. Avoid having undercut by pausing slightly at the side of a weave bead as it occurs. 

T joints are 90-degree angle joints. This type of weld on this joint is usually known as a fillet. Keep your gun at a 45-degree angle for this project. It should remain at equal distance from each piece of your weld joint. When you make multiple passes on the fillet joint, the work angles should change slightly to one side first and then to the other. This will avoid uneven beads and undercutting. 

Lap joints are another type of fillet weld. These joints require you to hold your gun somewhere between 60 and 70 degrees. This will direct more heat into the bottom piece of our metal. The thicker your metal piece is, the larger your angle should be. 

Horizontal Positions

Gravity automatically adds some force to your welds in this position, so your angle should change by 0 to 15 degrees to accommodate it. Your gun should now face upwards towards the top piece of metal in your weld. If you don’t change your work angle, you’ll end up with saggy filler that rolls over on the bottom side of your welded joint. The travel angle shouldn’t change. 

If you’re making multiple passes over thick metals when you weld, or you need to bridge a gap where the fit is bad, you should weave slightly to fill the joint. Pause for a moment at the top toe of your weld to prevent it from being undercut and ensure that your weld is properly tied into the base metal. Voltage and amperage settings shouldn’t change by much, but may be slightly less than in flat welds. 

Avoid Wire Feeding Problems

Burn back and bird nesting are the 2 most common types of wire feed problems. These will prematurely extinguish your arc and cause defects in your weld.

Burn back happens when your wire melts into a ball on your contact tip. Usually, this happens when your wire is feeding to slowly or when your gun is too close to your work piece. You can avoid this issue by using the right feed speed for your gun and job and keeping at least 1 ¼ inches from your contact tip to your work. 

Bird nesting happens when your wire gets tangled and stops the feed. Fix these issues by making sure you’re using knurled drive rolls. 

Stop Porosity and Worm Tracking

These 2 issues are commonplace. They weaken your weld integrity and cause discontinuity. 

Porosity happens when your gas gets trapped in the weld’s metal. Prevent it by removing rust, grease, and pain before welding. Filler metals with deoxidizers can also help.

Work tracking is when your gas causes marks in t he surface of your weld. You can prevent this by making sure that your voltage parameters watch the voltage and amperage recommended for your wire’s diameter and metal’s thickness. 

Eliminate Slag Inclusions

Dragging and pulling is a great way to avoid slag. The arc being dragged keeps spatter out of the joint, providing for a strong and clean weld. Never, ever push your flux weld if you’re trying to avoid slag. 

Prevent Undercutting and Lack of Fusion

The best way to prevent undercutting and lack of fusion is by making sure you have the right travel and work angles. Use the guide above to teach you the right way to weld your particular joint. Pay attention to the technique, whether it’s weaving or pausing. 

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Avoid Excessive Penetration or Lack of Penetration

Your weld’s safety and lifespan depend heavily on getting the right amount of penetration so it can properly fuse with the metal piece. 

Penetration is all about the angles. If you are experiencing a lack of penetration, try welding vertically uphill. Flux core MIG wire works really well to get better penetration into thicker metals than solid core welders are able to. 

Just weld vertically using an uphill motion to get that extra bit of penetration. Working back and forth up the job provides for a stronger weld than horizontal.  Using the right flux core wire can also give you more penetration. 

Practice, Practice, Practice!

Welding is a skill. To become good at skills, you need to practice them. Olympic athletes have almost no social life or free time because they’re training to be the best at their craft. The same is said of world-class dancers. 

This means that you shouldn’t get discouraged if your first welds don’t turn out that great. Welding will require practice, too. No matter how perfect your parameters are, it will take some practice to continuously keep the right angles and get the right techniques. 

Find out where your weld has fallen short and study techniques on how to improve them. Once you’ve read about how to fix those issues, go practice! Practice makes perfect. 


1. Do you push or pull flux core welding?

When welding with flux-cored wire, always use a drag (pull) technique, in which the tip of the welding gun is pointed back at the weld pool and dragged away from the completed weld. To remember whether to use a push or drag (backhand) technique, a simple rule of thumb is: "If there is slag, you drag."

2. Are flux core welds strong?

Yes. They enable a high rate of deposition. They perform admirably outside and in windy conditions. These electrodes, when combined with the appropriate filler materials, can transform FCAW into a “all-position” process. Generally, flux-cored wires produce strong, clean welds.

3. Is flux core welding easy?

MIG Welding With A Flux Core Is Simple And Economical

When using flux core MIG welding, you can begin welding immediately after unpacking. When welding with the MIG (metal inert gas) process, this slag is eliminated because the weld bead emerges smooth and clean.

4. Is MIG better than flux core?

By using flux core, you can weld thicker metals with less amperage than MIG. As a result, the argument that flux cores provide superior metal penetration is also valid.

5. Can you weld aluminum with a flux core?

No, is the short answer. You cannot weld aluminum with flux core wire made of steel in your FCAW welder. It will simply not work.

About the Author Gregory

Hi, my name is Gregory! I have been welding practically all of my life and love it. As I have gotten older I have started to weld less and less, so in order to continue my love for welding I created this website. I like to write about my experiences and help you all become welders. I hope that you enjoy the site!

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