Welding plays a huge part in our day-to-day lives and turn, the advancement of civilization. Just have a look around you, without welding, we couldn’t use any of the tools made of metals.

It is true that MIG welding is one of the best ways to repair metal stuff. However, it is not without risks and requires special knowledge. Guys engaging in the welding sector face a common problem called Burn-through that ruins the entire metal piece they’re working on.

Your attempt at creating something would simply turn into an unsightly hole in the metal if you do it wrong, what a drag! So in this article, I’m going to give you the right information so that you will know how to prevent burn through during MIG welding.

What is Burn-through?

Burn-through happens when the weld goes too deep and fully penetrates the main metal piece that you are working on.  In other words, when you melt the metal so much that you reach the weld root. That is why another name for burn through is melt through.

Usually, the main problem or defect seems to happen just right on the welding spot or a little bit side. You will face this while welding any thinner materials like ¼’’ or less thickness metal.

How To Prevent Burn-Through When MIG Welding

How to prevent burn through during welding?

When welders, especially beginners, perform MIG welding, they often burn through the piece of metal, be it a sheet or a pipe. They essentially melt the metal so much that they create a gaping hole in it. But this problem is not unavoidable, rather it is pretty easy to avoid once you know what causes this burn through.

In order for your work to be safe, there’s a certain technique you need to follow. The same applies in the case of MIG welding and following these ways you can prevent burn-through up to a significant level. Let’s have a look at those…

Preparing the metal for perfect welding

At the beginning of your welding tasks, it’s crucial to prepare the metal base to complete the welding smoothly & properly without any burn through.

Here comes the cleaning part. The first thing you should do is to assess any paint, layer, or coating on the metal surface.

If you see any coating then just remove it by grinding properly using a high-end grinder. Steel wool or grinder makes the perfect tools for removing the oxidation and rust from the surface layer.

After that, you can clean the metal thoroughly to make sure no dirt, oil, debris plus oxidation is left over the metal. For perfect MIG welding, clean metal is a must.

One note is very important and that would help you from unnecessary burn through. That is never try to work on a metal that was not welded properly if you have the option to do so. Always, starts your work with a fresh piece of metal.

Now you can use an angle grinder to clean the edges of the metal base and slope for preparing them for welding. While grinding bevels ensure to avoid over-grinding by leaving some materials at the bottom. It will prevent your aluminum, steel, or iron from getting burn-through.

Setting your MIG welding machine properly

Without any doubt I can tell you that a significant amount of burn-through happens because of the improper setting of the MIG welding machine. When you set the amperage setting to a higher level it would surely give you back a burn through.

Gauge numberFraction of an InchAmperage
183/64’’= .04747
10⅛ ‘’= .125125

Amp/Inch Formula M x 1000= A | M = Material A = Amperage

Avoid long arcing

Arc is the way of welding to join metals with each other. During the welding time, you use a high level of heat which leads the metal to melt and connect with other metals.

When the arc length will be more there will be a chance of high voltage leading to burn-through. So it’s recommended by the expert that you must ignore long arcing to make sure the reduction of voltage during welding with the MIG. Which will help you to save your base metal from having burn-through.

Avoid short arcing

This is not easy but you can do it by practicing gradually. All you need to do is avoid taking the electrode too close to the metal while welding. It will help you to avoid urn through as your electrode is not going to stick with the metal repeatedly.

Adjust the travel speed

Even though you maintain a moderate arc & keep the amperage not too high still there remains a chance of burn-through the metal piece. This can happen because of the travel speed of the weld pool.

In this case, travel speed refers to the speed you move the electrode on the base metal during welding time. For metals that have lower thermal conductivity, you should maintain a slower travel speed.

On the opposite, while welding metal such as aluminum that has higher thermal conductivity you must maintain a faster travel speed to ensure no damage to the metal.

Ensure proper electrode angle

Maintaining a shallow electrode angle will lead to less penetration in the base metal and the chances of burn through decrease a lot.

The most ideal angle position of the electors would be 45 degrees which is not too shallow or too steep. From this angle, you will be able to diffuse more heat & the ample amount of heat concentration on the base metal. Doing that will help you to prevent burn through.

Filling the existing metal gap slowly

The main focus to fill the gap of your metal base is to go slow. You can smoothly fill the gap with welding by giving it enough time after every welding.

Don’t go for welding on the gap until it becomes cool & not red hot anymore. When you see it became cool then again start welding on the gap.

Doing this will help you to avoid making the gap bigger & fill it properly. It will take a bit more time than normal time but it will pay off for sure.

Using the proper size electrode

This is extremely important to avoid any burn-through during MIG welding. For the best-case scenario always try to select and use the smaller wire diameter.

Small wires will give you more control during welding. Because of the lower heat deposition rates even if you make mistakes with it you have a chance to recover it.

The key point here is not to use filler metal which has more thickness than the base metal. Experts recommend that you should use .023-.024’’ wire while working on a light base metal.

Besides, you can use a 0.30’’ wire for welding when your base metal is at least 18 gauge or thicker than that. In addition, for welding mild steel or carbon steel, you can select an ER70S-6 electrode & this will help you to prevent any burn through on the metal from excessive heat.

Moreover, for welding stainless steel you can use ER308, ED308L, and ER308LSI to minimize the probability of burn through.

Less consecutive passes

The moment you start welding a joint, your steel pieces gonna be extremely hot. Then letting the metal piece cool-down would be much better than putting another weld on top of that and forming a burn-through.

You simply should not carry on welding one after another rather do your work by giving a little gap to avoid any kind of burn-through.

What causes Burn-through during welding?

There are some factors that cause burn through during welding. The Sooner you know the better you become an expert at preventing burn-through.

Let’s see what are those factors…

High Amperage

Most common reason behind burn through is the poor setting of the machine during welding time.

Not following the proper or recommended tuning of the welding machine create a high chance of facing burn through the base metal. High amperage cause too much heat input during welding & burn-through happens.

Improper Electrode Angle

Working on the base metal with a wrong angle will surely invite burn through and there will be holes in the metal. A slightly angled electrode has a lighter impact on the metal.

To put it simply, a steeper electrode angle will be closer to 90 degrees which creates more force & this extra force pass more heat into the metal workpiece resulting in burn-through.

Short Arcing

Short arcing means when you bring the electrode extremely close to the base metal. This situation can make the electrode stuck with the base metal piece. If you keep doing short arcing it will break down the strong metal & make a burn through.

Long Arc Length

The distance between your metal workpiece & the electrode tip is known as arc length. A longer arch means the electrode is way too far from the metal piece. It might create an unstable, imbalanced arc, and causes sprinkle-like welding.

Not only that, but it also becomes tough to control the movement of the arc to ensure appropriate heat dispositioning on the metal.

Finally, due to the overheating melting occur in the work zone creating another unwanted burn through wasting your productive time.

Excessive grinding work metal base

It’s pretty common that before the metal base goes to the welding process the beveling edge is already done. Edge beveling requires a specific amount of grinding to prepare the metal for welding.

However, what happens is that people often end up doing over-grinding making bevels that are too deep. And this additional metal depth becomes one of the main reasons for burn through.

Not adequate cleaning of the base metal

Before getting into the welding part it’s important to clean the base metal appropriately. Because in extremely high temperatures during welding metals such as galvanized steel and aluminum’s surface layer can become highly reactive.

If you are going to work on an aluminum piece that was not ground properly will have a thin layer, coating, or film of aluminum oxide. Which will react instantly during welding time resulting in spatter and finally another unwanted burn through in your work life.

Using a larger size electrode

It’s never wise to use a big size electrode on comparatively thinner steel. But this is a common mistake in the welding community and thus burn through keeps happening.

For example: if you want to weld a ⅛’’ steel base and select a 5/32’’ stick rod then the steel won’t be able to handle it and resulting in burn though.

Welding thin to thick steel

Often time you need to weld thin steel with thicker steel and that’s where the problem arises. A thicker metal can handle more heat during welding while a thin metal can’t do that.

People make the mistake of putting more heat on the thinner metal during welding, which led to burn-through easily.

Too wide of a gap

Part of the welding job people get metals that were not cut properly and there are existing gaps on the metal base. Many people end up having a bigger gap by putting too much heat on the gap and trying to weld it quickly with other metals.

Not giving the metal enough time to cool down makes the extra metal meltdown while filling the gap of the base metal which generates a burn-through.

Frequently Asked Questions

How can I prevent burn-through during welding?

You need to do some stuff before welding & follow some way during welding. It’s very important to clean or grind the surface layer properly & not to over-grind the surface layer to prevent burn through.
During welding you should make sure you are using the right size electrode, proper angle of the electrode, moderate arch length, setting the MIG welding machine properly, ample amount of high amperage, filling the existing metal gap slowly, less frequent passing & adjust the travel speed properly to prevent burn-through.

Can you fix a burn-through?

Generally, burn-throughs can be fixed if it’s not too big and make the metal piece too fragile. You can fix it by cleaning the metal, then doing small welding, waiting for cooling then repeating the process.

Why does burn-through happen when MIG welding?

Burn through happens when MIG welding because of excessive heat melting the metal due to the imbalance of parameters such as travel speed, exact required heat input & electrode angle, etc.

How bad burn-trough is for your base metal?

Burn through can have a devastating impact on the weld joint and reduce the strength f the joint. Adding to that, it also destroys the looks of the weld. The main problem is that it makes the metal fragile and prone to break under load.


Burn-through is backed by multiple factors & each one of them can be responsible for it. Welding is an art that needs a significant amount of time to become good at.

Mostly beginners to mid-level people face the burn though due to a lack of deep idea about how the MIG welding works best. In the whole process of MIG welding, you have to maintain some specific technique to prevent burn through.

I hope this article has given you an in-depth idea of how to prevent burn through when MIG welding.

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