The question that every welder might be having after using their MIG welders for a long period of time is “What is the correct Tungsten Electrode that I must use?” As professional welders, it is our duty to select the right type of power source and the appropriate tungsten electrode for the same. It also depends on the material that you weld on and its surface texture and thickness.
Tungsten is a very rare metallic compound used majorly used for manufacturing gas tungsten arc welding (GTAW or MIG) electrodes. MIG welding process extensively relies on the tungsten’s hardness and its resistance to very high-temperatures while welding. As far as chemists know, tungsten has the highest melting point of a majority of elements of around 3410 degrees Celsius.
With the huge variety of tungsten electrode types available, knowing and choosing the right one for you not only improves the weld performance and also saves a huge amount of time and money.
These electrodes are non-consumable and come in a variety of sizes and shapes and comprise of pure tungsten and other rare-earth elements. The base type material, thickness, and using a particular type of power supply either AC or DC makes you analyze and choose the MIG welding electrode accordingly.
Pure tungsten electrodes are green in color and contain 99.5% tungsten. They are the least expensive amount of tungsten electrodes and have the highest consumption rates amount their counterparts. When these electrodes are heated, they form a clean, balled tip and provide some immense amount of ac stability for AC welding with a balanced wave.
This pure tungsten electrode also provides a great amount of arc stability for AC sine wave welding mostly done on aluminum and magnesium metals. It is not ideal for DC welding due to stability issues.
Thoriated tungsten electrodes are red in color and contain around 97.3% tungsten along with 1.70-2.20% thorium and are called as 2% Thoriated Tungsten electrodes. These electrodes are highly used in recent times because of the user-friendly nature and longevity of its usage.
Thorium helps increase the electron-emission qualities of the electrode and increases the arc starting performance and also enables us to allow more current-carrying capacity. The most incredible feature about this electrode is that it has a very low melting point making it super-efficient as it has a very low rate of consumption. It also eliminates any form of arc wandering.
Compared to other thorium-based electrodes, these electrodes deposit a very small amount of tungsten into the weld puddle causing almost no weld contamination. Hence, these electrodes are extensively used for AC welding especially for thin-aluminum gauge sheets and other metals having a thickness of less than 0.06-inches.
The tungsten electrodes maintain the sharpened ends because of the dispersion of thorium during its manufacturing process throughout the electrode.
Ceriated tungsten electrode is orange in color and has a minimum of 97.30% of tungsten and 1.8-2.20 percent of cerium and hence its name. It is referred to as a 2% ceriated tungsten electrode. These electrodes can also perform well in AC welding operations and low amperage DC welding processes.
Ceriated tungsten is popular in applications like orbital tube and pipe fabrication, thin sheet metal works, and some jobs where we weld small and delicate parts. Just like thorium, it is the best way to weld carbon, steel, stainless steel, nickel alloys, and titanium.
I recommend no one to use ceriated-tungsten at a very high amperage because the oxide produced is released extensively via the contact tips nullifying all of its process benefits.
Lanthanated tungsten electrode contains a minimum of 97.8% tungsten and 1.3% – 1.7% lanthanum. Hence these electrodes are known as 1.5% lanthanated tungsten electrodes. These electrodes tend to have a low burn-off rate and a good amount of arc stability and good reignition characteristics, to begin with, welding.
Lanthanated electrodes have a very common conductivity characteristic like that of 2% thoriated tungsten. These electrodes work best with both AC and DC welding electrode negative with a pointed end.
These electrodes are different from thoriated tungsten as they are compatible with the AC welding procedure and allow the arc to be easily started and run at low voltage conditions. It has an additional 1.5% of lanthana addition that increases the maximum amount of current carried by it based on the electrode size we use.
Zirconiated tungsten electrodes have 99% of tungsten and the remaining amounts of around 0.15 – 0.4% zirconium. The zirconiated tungsten electrode helps us produce great arc stability and helps resist/prevent tungsten spitting. As it retains a balled tip, and has high-resistance to contamination from toxic environmental agents, and hence ideal for AC welding.
The current-carrying capacity of Zirconiated tungsten electrodes is much more than that of thoriated-tungsten electrodes.
Rare-earth tungsten electrodes contain maximum amounts of unspecified and unknown additives of rare-earth oxides and sometimes the hybrid combinations of those different oxides. It is necessary for knowledgeable and wise welders like us to identify the type of additive in the electrodes and the percentage present in them.
It is the type and number of additives present that make a stable arc in AC and DC processes. Using these electrodes can help us use a smaller diameter electrode for the same welding job that we had done earlier, use higher current all-along, and also produce less tungsten-splitting.
If you apply AC amperage that is recommended for a given electrode diameter a ball will form at the tip. For a pointed or truncated tip, you should use a grinding wheel that is specially designed, for it. To ensure that the grind marks run the length of the electrode, the grinding should be done straight and not at 90 degrees. It is used in pure tungsten, ceriated, lanthanated, and thoriated tips.
It should be used for inverter AC and DC welding processes. When using on thinner materials the taper should be ground on tungsten to a distance of no more than 2.5 times the electrode diameter. This helps in forming a focused arc formation and prevents the distortion of aluminum.
When a higher current has to be used, a truncated tip is needed. This can be made by first grinding to a thin taper and then grinding a 0.10″ – 0.30″ flat land on the end of the tungsten. This will prevent ball formation.
How do you prepare a tungsten electrode and which is the better one?
A balled tip tungsten electrode is mostly used for pure tungsten 2 types of the electrode and is most ideal for working with AC welding processes especially on sine wave and square-wave TIG welders.
Keep in mind when working with balled-tips that the balled end should not exceed more than 3/2 times of the diameter of an electrode because if you have a larger sphere as the end tip, then it can reduce arc stability and mostly contaminate the weld we make with utmost care.
In order to properly ball the end of the tungsten electrode, applying the required amperage for the given electrode diameter that you are using and the other end of the tungsten electrode will form the ball itself.
When it comes to the pointed/truncated tip of the electrode, using a grinding wheel to properly grind the tungsten is a basic process and must be made up of borazon or diamond. It is highly useful for AC as well as DC welding processes.
This type of electrode is effective for higher current applications. For better performance in your weld, it is recommended to grind the tungsten to a taper and once again grind it to about 0.10- 0.30 inches flat end of the tungsten. This flat-land shape end of the tungsten electrode mainly helps in preventing any bailing or falling -off of the electrode while welding.
When welding with very low voltages, and that too on thin materials, it is best to grind the tungsten electrode to a point. A pointed tungsten electrode resists distortion and porosity formation in these sheets of metal like aluminum by allowing the current passed to it into a tiny arc.
Sean Coby is a welder par excellence and well respected among the welding community in Woodbridge, VA. He prides himself to be the fabricator and mechanic in the automotive/ diesel industry for the past more than eight years now. As the chief editor of his https://weldinginfocenter.com, he shares his experience to be safe during welding and to take proactive steps for becoming a successful welder like him.