GTAW, or TIG welding as the American Welding Society officially calls it, is a welding process where the joining of metals occurs through the electric arc established between a non-consumable tungsten electrode and the base material, both protected in the welding zone, for an atmosphere of inert gas.
Tungsten Electrodes: TIG Welding's Most Important Piece
When it comes to TIG welding, tungsten electrodes are the most important part of the application. Since its development in 1941, it has sought to improve performance and performance through the addition of elements of high melting point and physical/chemical qualities that allow it to withstand the typical working conditions of this process.
In the AWS A 5.12 standard, the electrodes are classified according to the elements that are added to the tungsten electrode to acquire specific properties, summarized in the following table:
|Classification||SAE-ASTM||Percentage of weight (%)||Color|
|AWS||UNS||W (min.)||CeO2||La2O2||ThO2||ZrO2||Other elements|
|EWCe-2||R 07932||97.3||1.8 - 2.2||0.5|
|EWLa-1||R 07941||98.3||1.8 - 1.2||0.5|
|EWLa-1.5||R 07942||97.8||1.3 - 1.7||0.5|
|EWLa-2||R 07943||97.3||1.8 - 2.2||0.5|
|EWTh-1||R 07911||98.3||0.8 - 1.2||0.5|
|EWTh-2||R 07912||97.3||1.7 - 2.2||0.5|
|EWZr-1||R 07920||99.1||0.15 - 0.40||0.5|
As you probably have experienced, the electric arc carries a lot of determination of the welding results in a TIG welding application. There are times where it looks like everything is set up for an ideal process, then the end result doesn't match up. Is it improper welding technique? Poor gas coverage? I could be, but likely the reason stems from an unstable electric arc.
Why do we have an unstable arc? Most likely, it's the sharpening of our Tungsten electrode that's the cause:
When it comes to the correct sharpening of your electrode, the next question often is what does proper tungsten electrode sharpening look like?
The critical thing to know is that sharpening influences weld penetration, arc stability and, above all, weld quality, in addition to the electrodes respective durability.
A correct sharpening is one that gives the Tungsten an ideal shape, preventing it from being too pointed but not blunt. When using a Tungsten grinder and cutter, it is important to know that when using it you have to grind the tungsten electrode parallel to the wheel:
|Correct Tungsten Shape||Incorrect Tungsten Shape|
|Stable arc provides greater tungsten life||Unstable arc provides less tungsten life|
Here's a more clear demonstration of how the sharpening of the tungsten electrode influences performances:
|Poorly Sharpening||Well Sharpened (Ideal)||Overly Pointed|
Staying Protected While Sharpening Tungsten Electrodes
Knowing the importance and influence of the sharpening of the Tungstens in TIG welding, you might wonder how to achieve the ideal sharpening? At this point, we must talk about health and the welder's breathing zone.
Sharpening involves the release of harmful particles for welders and hence the importance of knowing where and how to do it.
During the process of sharpening, a variable amount of particles is produced that can penetrate small wounds and, above all, be inhaled through the lungs and the digestive system where they disintegrate and accumulate.
Studies on tungsten as a carcinogen have produced mixed results to date, but recent studies have shown exposure to tungsten concentration can lead to issues of the immune system. The greatest risk is the inhalation of the dust, the product of the sharpening, which is why it is important to use a sharpening system with a "closed process" that keeps the electrode covered at all times and protects the welder or laborer from overexposure.
Tungsten sharpeners exist that make this key task simple, accurate and safer.
Among Tungsten sharpeners out there, there are typically two types, for dry and wet process.
Dry Tungsten Grinders
A dry tungsten grinder is a portable piece of equipment that is easy to operate and helps in the repetitiveness of the sharpening.
Ideally but not always, dry electrode sharpeners will feature a "closed process" that limits exposure of tungsten particulates and sharpening powder to the operator. There are dry grinders that use powder where the operator will be exposed to it, and that can over time be potentially hazardous.
Always use proper localized ventilation or respiratory devices when using dry grinders.
Wet Tungsten Grinders
Wet tungsten grinders with a "closed process" allow for no exposure of the operator to the sharpening powder.
Wet grinders sharpen from 15 to 180º. They usually feature a greater durability of the sharpening wheel and cause less damage by heating the tungsten electrode during the process.
Easy removal of powders and sharpening liquid is normally possible with wet tungsten grinders. Like with the dry grinder, these are very easy to operate and have great sharpening repeatability.