TIG, or Tungsten Inert Gas, is a kind of welding using non-consumable tungsten electrodes, a shielding gas like argon or helium, and a filler rod to melt into a weld pool for deep, thick, robust welds. The resulting joints are strong and, when done properly, can be very even, level, and even beautiful. One thing that many people don’t know – or discover on their own in a moment of desperation – is that TIG can be performed without a filler rod at all.
What is a TIG without a filler rod? How does it work, what are the pros and cons, and should you learn how to do it? Let’s talk about it.
Is it Possible to Perform TIG Welding Without a Filler Rod?
Yes! Though many people stumble upon the technique on their own, it’s a well-known concept. Some people call it fusion welding; the official name for the technique is Autogenous TIG Welding. Specifically, it uses the TIG welding process to fuse two pieces of metal without using a filler rod.
Fusion welding has its place in the roster of techniques that welding operators should learn. The biggest questions are how it works when you should use it, and what its drawbacks may be. Let’s dig in a little deeper.
The process is performed just like any other TIG welding, except without the use of a filler material to absorb excess heat and keep the heat-affected zone to a minimum. That means you need to carefully control your arc, the amount of heat you put into the material, and the movement of the torch; any mistakes can easily burn through, warp, or otherwise hamper the finished joint.
When is Fusion Welding Most Commonly Used?
Fusion TIG welding is a process that joins two base pieces of material without a filler material, adding bulk to the finished piece. As such, it’s most commonly employed in situations where you’re joining two thin pieces of material and need tight joints where there isn’t a lot of excess material left over.
In short, the focus is on a tight, clean, precise joint without excess material that would need to be ground away anyway.
In contrast, fusion welding is not a commonly used process in cases where bevels and grooves are used to prepare the base materials and where extra material needs to be deposited to ensure the strength and penetration of a weld.
What Are the Benefits of Fusion TIG Welding?
TIG welding without a filler rod has a handful of distinct advantages that a skilled welding operator can take advantage of in their finished pieces.
First and foremost, it allows you to perform welds with a reduced heat input. Normally, you need enough heat to melt the work surface of both base materials to an appropriate depth, along with the additional heat necessary to melt the filler rod and mix it into the weld pool. When you aren’t using a filler rod, you don’t need the additional heat that would be added to the workpiece.
The biggest benefit of this is that it reduces the heat-affected zone of the weld. Since fusion welding is most commonly used on thin materials, warping and distortion are a primary concern; by reducing the amount of heat you need to put into the piece, you have less of a chance of distortion, warping, or burn-through.
The second benefit is that the welds you produce are, when done properly, more aesthetically pleasing when completed. While this isn’t always a primary consideration, it can be, especially for welds that are decorative, part of art pieces, or are part of a surface that will be visible to normal people. While messy, bulky welds can be strong and effective, they look like they might have been performed poorly, and that can reflect poorly on whatever is being welded in the first place. In extreme cases, it can make people distrust the structure of a weld.
While you can always finish a weld by grinding and blending in the filler and the base materials, the cases where you would use fusion welding have less leeway for this kind of treatment. Moreover, grinding a weld can reduce its strength and can expose surfaces to oxygen, requiring additional treatment depending on the metals involved.
The third benefit is that fusion welding can save you some money. TIG welding without a filler rod is cheaper than TIG welding with a filler rod, solely because those filler rods cost money. While this might not be much when you’re handling common materials, it can really add up if you frequently perform welds using rare or expensive alloys, and when you’re operating at scale and with a large volume of items produced, even small savings on each weld can add up over time.
This is also part of why fusion welding is commonly used in automated fabrication, but we’ll discuss that more later.
Finally, fusion welding can help keep a workpiece from corroding. Heat tends to make metals more susceptible to corrosion, but more importantly, a filler rod is a different metal being added to the mix, and that can introduce contaminants, change the composition of the metal, and leave it more susceptible to corroding both right away and over time. While this can be fought, you can also help avoid it by using fusion welding instead of TIG with a filler rod.
What Are the Drawbacks of Fusion TIG Welding?
TIG welding is traditionally performed using a filler rod; it’s how the process was designed to operate. Technically, operating without a filler rod is a different process, but since they function with the same torch in the same way, they are easily compared. So, what are the drawbacks of using TIG welding without a filler rod? There are a few, and they can be very meaningful in certain circumstances.
First and foremost, TIG welding without a filler rod doesn’t really work on thicker materials. Thin materials make it easier to achieve the required penetration and mixing of the materials to join them together. Thicker materials need that filler rod to help add both heat and material to the mix for a more robust joint.
Secondly, a joint made without a filler material will be weaker than the same joint made with a filler material. Filler material serves more purposes than just helping fill in grooves and allow welds to be deeper; it adds material, often a material that is stronger than the base material, which strengthens the overall joint. Since the base materials are already going to be on the thin side, the joint you produce with fusion welding is generally going to be relatively weak. Thus, unless otherwise analyzed and confirmed, fusion welding is not the best option for structural welds.
Another drawback is that fusion welding without a filler rod is very difficult to perform comprehensively and with uniform penetration. The filler rod material helps to evenly distribute heat and penetration across a joint. Depending on the configuration, fusion welding can have a difficult time achieving full penetration across the whole of a joint. Since weaknesses in the joint can be a source of cracking or breaking, and since these joints are already going to be weaker because of the thickness of the materials, this can result in very fragile joints.
Similar to the above, fusion welding is simply a very difficult technique to perform. TIG welding itself is one of the more complex welding processes to master, in part due to its versatility; TIG Fusion welding is another step beyond in terms of difficulty. You need very precise control over the parameters of the weld, which means knowing exactly how much arc, how much heat, how fast and consistent to move the torch, and more. If any factor is out of balance, catastrophe awaits.
How to Best Perform TIG Welding Without a Filler Rod
If you’re interested in learning how to perform fusion welding, the process is relatively similar to basic TIG welding, just with very little margin for error.
Step 1: Prepare your workpieces. Since you aren’t using a filler rod, your joint needs to be immaculate; make sure the surfaces are clean and free of any potential contaminants like grease, rust, paint, or coatings. Similarly, ensure that they are shaped to fit together perfectly; you don’t have filler material to help fill in gaps or smooth over roughness in the seam.
Step 2: Configure your system. Your TIG machine needs to be set up to weld the materials you’re working with, which means you need to know what those materials are and how they will react. Make sure you’re using the right kind of electrode, an appropriate shielding gas (usually Argon), and any additional tools you may need on hand.
At this point, you can perform a test arc. Adjust the settings on your machine to produce the right kind of arc with the right length and heat output necessary to fusion weld the materials you’re welding. You need to be very familiar with the settings on your machine and what they mean so you can adjust them properly for your joints.
Step 3: Perform your weld. As you weld, make sure you’re moving your torch at a consistent speed, maintaining heat output, arc distance, travel speed, and penetration consistently. The more complex, awkward, or variable the workpieces you’re welding are, the harder this will be.
All the while, you need to be paying very close attention to the weld pool as you weld. You may need to adjust the torch angle, speed, or distance to ensure proper penetration without going overboard and burning through your material. This can take a lot of experience, which is why it’s an advanced technique.
A Better Alternative for Fusion Welding
Because of the very precise nature of fusion TIG welding without a filler rod, you need to be highly skilled, accurate, and precise, almost like a machine.
So, why not let a machine do the work?
In fact, small-item fabrication is one of the best use cases for fusion welding.
- It works on smaller and thinner items, particularly those that don’t need to be structural.
- It can be repeated indefinitely with very precise, accurate results.
- Robotic configurations don’t change from piece to piece and only need to be adjusted if something goes wrong.
- When producing numerous copies of a given weld, such as in mass production and fabrication, the cost savings from not using a filler add up a lot faster.
This kind of welding is commonly seen in certain industries for this reason. It’s very useful for welding stainless steel pipes, tanks, and other equipment that needs to be clean and sanitary, such as in the food and beverage industry.
It’s also very useful for welding aluminum and its alloys, so it’s often seen in the automotive and particularly aerospace industries. You can also find fusion welding in fabrication that involves thin sheet metal, as well as any welding application that requires high purity in the original materials and cannot be adulterated with a filler.
Getting Started with Fusion Welding
If you’re interested in getting started with fusion welding, there are a few things you can do to make it easier on yourself.
The first is to make sure you have a very good TIG welder on hand. Since you need precision and accuracy, a subpar machine will cause you more problems than it’s worth. Our welding equipment rentals can give you a leg up on fusion welding for that reason.
Secondly, you can consider investing in welding automation tools. Whether you get a table that rotates so you can hold your torch steady or a fully automated welding system, fusion is much easier to perform when some of the variables are taken out of your hands. The more consistent you can be, the better off you’ll be with fusion welding.
If you’ve ever considered exploring TIG welding or want to invest in a system, we’re here to guide you every step of the way. Beyond just answering your questions, our rentals offer a unique opportunity to try before you buy. We provide top-tier TIG welding rentals, allowing you to familiarize yourself with different systems and techniques.
Why is renting a good option? You get to experience firsthand the functionality and efficiency of the equipment. For instance, instead of solely relying on an external technician’s expertise, you can rent high-quality welding equipment from us and test its compatibility with your needs. Each piece in our rental fleet is meticulously inspected, cleaned, and guaranteed to be in peak condition when rented.
Should you encounter any challenges or require maintenance, our dedicated team is on standby to assist. Additionally, if you’re looking to upgrade your current welding gear, our rental system is perfect. You can rent a machine, use it for a while, and, based on your experience, decide whether to purchase or continue renting it. If it’s not the right fit, simply return it and try another one. Our goal is to ensure you have the right tool for the job.
With an extensive range of TIG welders, multi-function welders, welding automation tools, and more, we’re confident you’ll find what you need. Not sure where to start? Just reach out to one of our experts, and we’d be happy to assist you.
