TIG welding is a little more complicated and takes a little longer than other types of welding, but it also produces better welds on materials that are difficult or impossible to weld with other methods. Though there are a lot of things to take into consideration when TIG welding, there is relatively little that you’ll need to begin TIG welding properly. In fact, if you already are a welder, you probably have most of the necessary equipment already.
What do you need to TIG weld the right way, right away? Like any form of welding, you’ll need protective equipment (such as a welding mask, long sleeved shirt, welding gloves, and closed-toed shoes), a well-ventilated work area, and a power source (in this case, you’ll want on that can run both AC and DC). Specifically for TIG welding, you’ll need a torch with a non-combustible (usually tungsten) electrode, and a ceramic cup through which to blow a shielding inert gas (usually argon).
TIG welding is a form of arc welding in which the weld area is protected by a cone of inert gas, both ensuring a pure join and allowing the welding of particularly thin and/or reactive metals. Essentially all you need is a source of electrical current, a non-combustible electrode, and an inert gas to shield the weld area. There are so many factors to consider when TIG welding, however, that it’s important to take a closer look at each component.
How TIG Welding Works
Tungsten inert gas (TIG) welding is also known as gas tungsten arc welding (GTAW). A non-consumable is used, so the metal from the electrode doesn’t contaminate the weld puddle. Tungsten is usually used because has the highest melting temperature among pure metals, at 3,422 °C (6,192 °F), and therefore doesn’t typically melt and contaminate the weld by introducing traces of the electrode’s element.
The purity of the weld is so dependent on the absence of contamination that if the tungsten electrode ever touches the weld puddle, it must be reshaped (preferably in a grinder used only for grinding tungsten) before the next weld.
The weld area is further protected from oxidation or other atmospheric contamination by an inert shielding gas. The type of inert gas used varies depending on the type of material being welded, the joint design, and the desired final weld appearance. Typically argon is used because it helps prevent defects due to a varying arc length. In heliarc welding, helium is used as the inert shielding gas in order to increase the weld penetration of the metal, increase the welding speed, and to weld metals with high heat conductivity, such as copper and aluminum.
The work lead (often referred to as the ground cable) is attached to the work piece or the metal surface that the work piece is on.
Overview of the TIG Welding Process
- One hand holds the electric torch. The torch contains the tungsten electrode protruding about 1/8th of an inch from a ceramic cup through which an inert gas is blown. The torch must be held close enough to the work piece to ensure that the arc is small and contained within the inert gas, but not so close that the electrode ever touches the work piece or weld puddle. You can tell if this has happened because it will result in a different sound and color.
- The other hand holds filler metal, which the welder feeds into the weld area as needed. Typically this metal is used to bond two work pieces together, though, in autogenous welds, such as spot welding, no filler metal is used.
- When the torch and filler metal are in place, the arc is struck by engaging the TIG welder with a foot pedal or a button on the torch itself.
- Once the maximum amperage has been set, the foot pedal can be used to gradually initiate and reduce the amperage and resulting heat. This soft starting and soft stopping prevents temperature shocking of the metal, which can be important when welding certain metals such as alloy steels used in auto racing.
- Thermal shock can result in brittle welds. With a high-frequency start, such as is used when utilizing a button on the torch itself, a brief surge of extremely high voltage is issued in order to initiate the arc up to one inch away from the work piece, then is lowered to the preset amperage.
- When the arc is struck, the torch is first moved in a small circle to create a weld puddle. Then the torch is tilted back 10 to 15 degrees from vertical and moved along the seem, with filler metal added to the front end of the weld pool as needed. The filler metal is removed from the weld puddle whenever the torch advances but is not removed from the cone of inert gas so as to avoid contamination and oxidation. Again, it is essential that the tungsten electrode is kept about 1.5–3 mm (0.06–0.12 in) from the work piece at all times.
Advantages of TIG Welding
TIG welding is a very specific process that offers several advantages.
- It uses less amperage than other methods. The low amperage used makes it ideal for joining metals that are very thin or cannot handle high amperage.
- It is versatile. Just about every variable in the TIG welding process can be altered to accommodate welding different metals for different purposes.
- The torch is small, making it capable of welding in difficult positions.
- High quality welds are produced because the inert gas and tungsten electrode prevent oxidation and other types of contamination.
Disadvantages of TIG Welding
Of course, these benefits come at a cost. TIG welding also has some disadvantages.
- It’s hard to learn. There are so many variables that many hobby welders are too intimidated to even try TIG welding.
- It’s slow compared to other methods.
Now that we have a basic overview of how TIG welding works, we can take a closer look at the specific components, which can vary dramatically depending on the conditions of your welding project.
Necessary Equipment to Get Started TIG Welding
Every component of your TIG welding rig can be adjusted to provide different desired results depending on conditions such as the type of weld, the metals being joined, and the work environment. Understanding what settings to use for different situations is what makes TIG welding so versatile, but it also makes it difficult to master.
TIG welding power supplies are basically the same as stick welding power supplies in that they are constant amperage power supplies and heat settings are regulated in amperage. In fact, a basic TIG torch could be attached to a stick welding power supply and work just fine. What TIG welding power supplies offer, though, are a lot of settings that help control the arc and adjust for different metal properties.
Some settings you’ll likely see on most TIG welding power supplies include:
- Amperage – A constant or maximum amperage allowed when the arc is struck is set with this.
- AC frequency – This knob allows you to weld at a much higher frequency than the 60hz supplied from most outlets in the United States. (In some countries the standard is 50hz.) power from the power company is roughly 60hz in the USA and 50 Hz in some countries. An inverter increases the frequency of the AC power before converting to DC, allowing for a more focused arc that can heat a very precise area without damaging nearby components.
- AC balance – When operating in alternating current (AC), the tungsten electrode alternates from being positive to negative many times a second. This knob lets you adjust the ratio of how much time it spends as positive versus how much time it spends as negative. If you’re welding something with an oxide layer, you’ll want this ratio to be about 50/50, so when the electrode is positive it blasts away the oxide layer, and when it is negative it melts the base metal. On brand new, unoxidized metal, you’ll want to adjust the setting to spend more time negative since there is no oxide layer to remove.
- 2t – This setting makes the torch trigger a 2 position switch. The arc is either struck at full amperage, or it is off.
- 4t – This setting makes the torch trigger a 4 position switch. Pushing the trigger starts the arc at a lower amperage. Releasing the trigger makes it upslope to the maximum amperage setting. Pushing the trigger again down slopes to a lower amperage, and release it stops the arc.
- TIG high freq versus lift arc versus scratch start – The TIG high frequency setting of this switch causes the arc to start at a high frequency so the arc can start from a greater distance from the work piece. The lift arc setting allows you to weld without high frequency. The scratch start setting is essentially the default setting of a stick welding power supply, which many people are more familiar with.
- Pre-flow – This sets the length of time, the torch gas flows between the time you press the switch or remote foot pedal, and when you actually get an arc. It is typically less than half a second.
- Post-flow – This sets the length of time the torch gas flows after the arc terminates in order to keep the molten filler metal from the atmosphere while it cools and solidifies.
- Upslope – This is the rate at which the amperage increases from the initial amperage when the arc is struck to the maximum amperage set.
- Downslope – This is the rate at which the amperage decreases from the maximum amperage, so the sudden termination of the arc doesn’t leave a defect like a fish eye or crater crack.
- Start amps – The amperage set when the arc is initially struck before it upslopes to the maximum set. This can prevent thermal shocking the base metal.
- End amps – The amperage set to downslope before cutting out.
- Pulse frequency – This setting adjusts how many pulses per second there are. Higher pulse rates tend to focus on the arc.
- Peak pulse percentage – This lets you control the effect of pulse in order to limit the heat input or just to agitate the puddle.
- Pulse width – This sets the amount of time the high pulse amperage stays on.
With these settings, TIG welding is extremely customizable. This is part of why TIG welding can join particularly thin metals and those metals with properties that make them difficult to weld with other methods.
What makes TIG welding unique is that the torch is designed to encase the electrode in a field of inert gas so that the molten metal of the weld is not exposed to oxygen or other contaminants in the atmosphere. As such, it has specialized features.
The handle itself is either air-cooled or water cooled. Air-cooling is simpler and results in a lighter, easier to handle torch. Some welders, however, report that they can usually only TIG weld for about ten minutes before they need to take a break to let their torch handle cool.
A water-cooled torch, on the other hand, is cooled via water that flows through tubes within the handle. The hot water is then carried to a water tank when the heat is dissipated by a fan blowing air over coils the water passes through before cycling back to the handle, cooled.
This method is more effective, but does require additional weight, decreased agility, and requires regular maintenance. If you only occasionally TIG weld, it may not be worth it, but it is essential in manufacturing settings where the same weld is repeated ad infinitum and speed is a factor.
TIG welding uses a non-consumable electrode to deliver the current to the welding arc. Tungsten is used because it has the highest melting temperature among pure metals, at 3,422 °C (6,192 °F), and therefore doesn’t contaminate the weld by introducing traces of the electrode’s element. The purity of the weld is so dependent on the absence of contamination that if the tungsten electrode ever touches the weld puddle, it must be reshaped (preferably in a grinder used only for grinding tungsten) before the next weld.
Different conditions, however, sometimes require different types of electrodes.
- Pure tungsten electrodes are affordable and provide a stable arc on aluminum and magnesium, especially when using a balled tip.
- Thoriated electrodes are the most common electrodes used because thorium is mixed into the tungsten to make a stronger electrode tip, which will remain sharp and last longer than pure tungsten. When working with thoriated electrodes, you must have adequate ventilation and safety precautions in place, though, because it is slightly radioactive.
- Ceriated electrodes are often used on DC applications with low amperage projects or small, intricate parts.
- Lanthanated electrodes are very versatile and will work on AC and DC power machines. They provide stable arcs and work well on low currents.
- Ziroconiated electrodes are used on AC projects where you need a strong electrode that’s resistant to contamination.
- Rare-earth electrodes offer a stable arc for AC and DC projects and have a tendency to last longer.
Electrodes come in diameters ranging from .04 to ¼ inch, though a diameter of 1/16 to 1/8 is suitable for most applications. The shape of the electrode’s tip affects how the arc travels to the metal, so the electrode needs to be shaped for different functions.
When welding a ferrous metal like steel, for example, you’ll want a pointed tip to concentrate the arc onto the metal. You can sharpen the electrode to a point using a grinding wheel. Preferably you should use a grinding wheel that’s only used for this purpose, so the electrode isn’t contaminated by remnants of other metals.
You’ll also want to avoid breathing any dust created as tungsten is slightly radioactive. A more consistent and method is to use a tungsten electrode sharpener that works just like a pencil sharpener.
When welding non-ferrous metals like aluminum and magnesium, on the other hand, you’ll want an electrode with a rounded or tapered tip, so the arc is spread over a wider area. To accomplish this you actually melt the electrode by running the TIG welding on DC power with the electrode set as the positive pole (DCEP), starting the arc on a piece of copper (or another clean piece of metal) with the argon gas on.
With the amperage high enough, the tungsten will melt, forming a drop on the tip. You can then stop the arc, allowing the tungsten to cool, switch to AC power and begin welding.
The torch’s ceramic cup acts as a nozzle to shape the cone of inert gas that shields the weld from contamination. The cups, which are usually pink, come in a variety of sizes that affect the size of the inert gas cone. Typically the numbering system corresponds to how many 16th of an inch wide the diameter is, such that a #5 is 5/16th inch wide, and a #9 is 9/16th inch wide.
Ideally, the tungsten electrode protrudes from the ceramic cup about 1/8th inch. When tilted at a 10-15% angle to led the weld puddle, you should be able to rest the edge of the ceramic cup on the metal, ensuring that the electrode is always a consistent distance from the metal as you move along the seam. This is a technique known as walking the cup.
Inert (Shielding) Gas
An inert gas is pumped through the TIG torch and into the ceramic cup, which creates a cone around the tungsten electrode in order to prevent oxygen or other contaminants in the atmosphere from interacting with the molten metal, which would compromise the integrity of the join. The gas supply is typically a tank separate from the power supply, so it’s important that you check that the gas valve on the tank is open before welding.
The type of inert gas used varies depending on the type of material being welded, joint design, and desired final weld appearance.
- Pure Argon gas is most commonly used because it can be used on any type of metal, it provides an effective shield, and it helps prevent defects due to a varying arc length. When using pure argon gas, the arc is narrow and concentrated, so you get a very precise weld, and the outer areas of the arc do not overheat while welding.
- Argon and Helium gas mixtures are used with increased amperage to achieve hotter welds because the helium conducts heat so that it reaches the edges of the weld pool.
- Argon and Hydrogen gas mixtures are sometimes used because the hydrogen (at a concentration of 5% or less) increases the heat while welding and creates a wide, hot weld bead that penetrates deep into the metal.
- When helium gas is used as the inert shielding gas, it is known as heliarc welding. Helium is used to increase the weld penetration in a joint, increase the welding speed, and to weld metals with high heat conductivity, such as copper and aluminum.
While one hand holds the TIG torch in place and creates the weld pool, the other hand manually feeds the weld pool with the filler metal that will form the join. The type of filler metal you use will vary greatly depending on what materials you are welding. The trick to TIG welding is to keep the filler within the cone of inert gas at all times to avoid contamination of the weld, but ensure the metal never comes in contact with the tungsten electrode to avoid contamination of the electrode.
Foot Pedal (or Torch Switch)
There are a few different ways to initiate the arc and begin the weld. One way is to set up your TIG welder power supply to manual start, in which case as soon as the electrode is in range of the work piece the arc is triggered. More commonly, you’ll want to get the TIG torch and filler metal into place and then trigger the arc with either a switch on the TIG torch or a foot pedal.
If using a switch on the TIG torch, when you push the button, the arc is triggered, and the welding begins.
- If using the 2t setting, the switch is either on at the amperage set on the power supply, or it is off.
- If using the 4t setting, pushing the trigger starts the arc at a lower amperage. Releasing the trigger makes it upslope to the maximum amperage setting. Pushing the trigger again causes it to downslope to a lower amperage, and releasing it stops the arc.
If using a pedal, you have even more control over the amperage. The pedal is pressure sensitive and works in the same way that a gas pedal in a car works. Pushing the pedal only slightly will result in a low amperage, and pushing it harder will result in the full amperage up to the maximum set on the power supply settings. With this control, you can ease the amperage up and down yourself, giving you control of the heat during each phase of the weld.
If the TIG High Frequency Start setting is selected on the power supply, when the switch is first triggered, it will start at a high frequency that can create an arc even across an inch of space between the tungsten electrode and the metal. The frequency then drops to the preset amperage. This feature is useful for keeping the tungsten electrode a safe distance from the weld pool, in order to prevent contamination.
Essential Safety Gear for TIG Welding
Welding is extremely dangerous. Not only do you have to deal with electrical currents and hot molten metals, but the light produced can damage your eyes, and toxic gases can be formed when the metals or contaminants on the metals are heated. Welders need to protect themselves with adequate protective gear.
- Light and thin leather gloves protect from heat and electric shock.
- Long sleeved shirts with a high collar protect skin from sprayed molten metal.
- Opaque helmets with dark eye lenses and full head and neck coverage protect against UV damage. Because TIG welding does not produce smoke, the light produced during the weld is brighter and more intense than other welding methods.
- Liquid crystal-type faceplates that self-darken upon exposure to the bright light of the struck arc protect eyes from bright flashes and UV exposure. A welding helmet with a fixed tinted lens could also be used, but the self-darkening lens allows you to get the TIG torch in place with the shield down, reducing the chance of it coming out of place when you nod it into place.
- Transparent welding curtains made of a polyvinyl chloride plastic film protect nearby coworkers from the UV rays produced during the electric arc.
- Proper ventilation or gas masks protect from toxic gases. The arc of a TIG welder can break down surrounding air to form ozone and nitric oxides or break down cleaning and degreasing materials to form poisonous gases. Though ozone and nitric oxide levels are typically moderate, exposure duration, repeated exposure, and the quality and quantity of fume extraction can cause emphysema and edema of the lungs, which can lead to early death.
It is always better to be safe than sorry. Now that you have everything you need, you can get started TIG welding the right way, right away.