Using a proper tungsten tip shape and a correct tungsten grinding method are necessary to achieve high-quality TIG welds. An incorrect tungsten electrode tip can lead to poor penetration, burning through, and arc wonder.
This article will teach you which tip shape is suitable for your application and how to actually shape the tungsten electrode.
Photo by @l0rdwelder
Tungsten Tip Shapes - Which To Use?
The tungsten electrode tip shape you need to use depends on the welded materials, joint thickness, and the bead profile you wish to make.
You can weld all metals with a pointed or truncated tungsten electrode using AC and DC TIG welding current. But, welding aluminum may sometimes require a balled, hemispherical tungsten tip. However, pointed tungsten with a small ball at the end works well too. We'll get to how to ball up or grind the tungsten in a second, but let's first discuss the different tip shapes and how they impact the weld.
Sharply ground tungsten tips, between 15 and 30-degree angles, provide lower penetration and wider bead profile. Additionally, the arc is more stable, but the chances of tungsten erosion and weld contamination are higher.
Larger than 60-degree angles provide higher penetration but a more narrow bead profile. These electrode tips are less likely to erode in the weld pool, but the arc is prone to wandering, which reduces arc control.
A 30 to 60-degree tip angle provides the best of both worlds for most jobs. You get adequate penetration and excellent arc stability. But the exact angle depends on your preferences and welding technique. So you should try a few angles to find the the tip shape that suits you the best.
However, you can benefit from very low tungsten grind angles when welding outside corner joints or thin stock. A sharp, 15-degree angle will widen the arc coverage and reduce penetration, which is often desirable when welding outside corner joints or performing lap welds.
Image showing tungsten tip angles and resulting arc width and penetration.
After sharpening the tungsten to desired grind angle, it's often a good idea to flatten the tip slightly. This will prevent tungsten erosion and tiny tungsten particles from contaminating the weld joint. But don't overdo with the flattening. The width of the flat tip should only be about 10% of the tungsten electrode width.
30 to 60-degree angle
Above 60-degree angle
Wide bead profile
Moderate bead width
Narrow bead width
Higher chance of tungsten erosion
Lower chance of tungsten erosion
Low chance of tungsten erosion
Arc tends to wander
Best used for thin sheet metal welding at low amperages and outside corner joints
Used for most welding jobs
Rarely ever used
AC TIG Welding Of Aluminum - Tungsten Shape
We mentioned earlier that you may need to ball up your tungsten electrode's tip when welding aluminum. This is a well-accepted practice used for decades when AC TIG welding aluminum. But, you don't have to completely ball up your tungsten electrode as was necessary in the past.
If your AC TIG welding machine has the ability to set the AC balance between DCEN (penetration) and DCEP (cleaning action), you can reduce the DCEP, and you won't need to ball up the tungsten electrode. The positive current (DCEP) is what concentrates too much heat on the tungsten electrode and causes it to ball up or even melt away.
Source from: https://slideplayer.com/slide/4475590/
But, if you use a pointed tungsten electrode with adequate thickness for the amperage you are using and reduce the DCEP to 30% or below, your tungsten tip will only slightly ball up. As a result, you can weld with more precision.
However, you should also try a fully balled-up tungsten tip to know which one you'll like the best. So, to ball up your tungsten electrode, you need to set the AC balance as high as possible to the DCEP side. So, adjust the DCEP to a maximum and DCEN to a minimum. This will focus most of the energy on the tungsten electrode tip. Afterward, proceed to initiate an arc on a scrap piece of metal with high amperage to melt the tungsten tip into a ball shape.
Aluminum tig welding on alternating current with the a/c balance set to max cleaning.
Source from: https://www.weldingtipsandtricks.com/tig-welding-aluminum.html
Check the electrode specification if the manufacturer suggests the ball-up amperage. If not, try different amperage settings until you find the sweet spot. Keep in mind that an overly strong current can melt thin tungsten rods with a high DCEP balance setting.
An alternative is to use a DC TIG welding output with the TIG torch attached to the positive polarity and the ground clamp attached to the negative polarity. Essentially, this achieves the same result. The electrode is positive (DCEP), and since tungsten cannot withstand the concentrated current on its tip, it melts and turns to a ball shape.
Aluminum tig welding on DCEN or Direct current electrode negative.
Source from: https://www.weldingtipsandtricks.com/tig-welding-aluminum.html
The size of the hemisphere ball at the tungsten's tip should not exceed 1-½ times the electrode's diameter. If it does, the ball may fall off when heated.
Keep in mind that pure tungsten or zirconated tungsten electrodes are used when AC TIG welding aluminum. They ball up the best and have good arc characteristics.
Tungsten Electrode Shaping Methods
To shape the tungsten tip to a sharp angle, you can grind it or dip the tungsten in the chemical solution. But pretty much everyone grinds their tungsten electrodes because it's more reliable, and you have better control over the result.
We recommend using our YesWelder Tungsten Electrode Sharpener that allows easy and precise tip shaping. It lets you shape the angle from 10 to 30 degrees, which most people need. While we pointed out that a 60-degree angle is usable, it's rarely required.
The YesWelder tungsten sharpener works with 1/16", 3/32", and 1/8" (1.6mm, 2.4mm, and 3.2mm) tungsten diameters and allows you to flatten the tip as we previously discussed. Additionally, it has a built-in cut-off option to cut and remove the contaminated parts of the tungsten electrode. As a result, you'll get clean cuts instead of splintered tungsten when breaking the tungsten manually.
Another option is to use a grinding wheel to grind the tungsten. This is a less reliable solution, but if you are experienced, it works well.
Source from: https://www.iforgeiron.com/topic/67255-experimental-jig-for-sharpening-tungsten-electrodes/
Grinding the tungsten electrode requires placing the tungsten's axis perpendicular to the axis of the grinding wheel. You should never grind the tungsten circumferentially. Tungsten electrodes must be ground in a linear direction. Otherwise, the arc will wander, and the chances of tungsten inclusions increase.
Image showing correct and incorrect tungsten grinding direction relative to the grinding wheel.
Image source: https://weldknowledge.com/2015/08/14/effect-of-tip-angle-of-tungsten-electrode-and-proper-grinding-techniques-gtaw/
Grinding thoriated tungsten electrodes requires additional safety measures. Thoria is a radioactive compound, and it's present in the red, thoriated tungsten. So apart from standard safety measures when grinding, using a mask respirator and having a local dust extraction when grinding thoriated tungsten rods is recommended.
Other tungsten electrodes don't contain radioactive compounds like thorium oxide, so their grinding dust is safer.
Trust YesWelder For Your Tungsten Electrodes
Most welding jobs require a truncated, 30-degree angle. But some people like to go a bit higher than 30 degrees. You should try a few tungsten tip configurations to see which works best for you. But, when welding thin metals, go with a pointy sharp, 15-degree grind angle.
If you need tungsten electrodes, YesWelder has you covered. We sell all types of tungsten electrodes, from pure tungsten to lanthanated, ceriated, and thoriated.