If you’ve just bought yourself a TIG welder, or you’re tossing up about whether you want to get one, but it seems too complicated, then you’re not alone. TIG welding can seem intimidating, but you’ll be an expert in no time if you follow our simple guide.
What is TIG welding?
Tungsten Inert Gas (TIG) welding is the process in which an arc is formed between a tungsten electrode and the workpiece to join the metals together. A filler rod is often fed into the weld pool by the operator to create a weld. A shielding gas is also required to protect the weld from atmospheric contaminants that could cause weld defects such as porosity.
TIG welding is considered the most challenging type of welding to learn as there is a lot more room for human error.
There are several different types of tungsten, each with their own unique properties and limitations.
- Pure tungsten (Green tipped)
- Thoriated 2% (Red tipped)
- Ceriated 2% (Grey tipped)
- Lanthanated 1.5% (Gold tipped)
- Zirconiated 0.8% (White tipped)
- Rare Earth (Purple tipped)
The tungsten that best fits your job will mainly depend on your parent metal and application, as not every tungsten will work with every metal. The thickness of your workpiece will also be a factor in which tungsten you’ll need.
Each type of tungsten comes in a range of diameters so that you can do precise and appealing welds. A good rule of thumb is the thicker your workpiece, the thicker your tungsten and vice versa.
If you’re just starting out and learning TIG, we recommend using the gold tipped Lanthanated or the grey tipped Ceriated. They’re both great general purpose, AC/DC compatible, and weld well on all metals, including aluminium (which is a much harder metal to work with, so don’t worry about it just yet).
Now that you’ve selected the tungsten that fits your job, the next step is to prepare it for the weld.
Before you start, make sure that you are prepping the non-coloured end of your tungsten. The tungstens are colour coded because they are almost identical in appearance. You don’t want to grind off your coloured end, as you won’t know what it is later.
There are a few different ways to prepare your tungsten, and different shapes will give different results on different applications.
A balled tip is usually recommended if you are using a pure or zirconiated tungsten and welding aluminium. This is a pretty easy shape to make, as you simply set your machine to the recommended amps on AC, turn it on, and the tungsten will automatically form a ball on the tip.
The other option is to set your machine to DC electrode positive (DCEP), hold the torch 90° on a piece of copper and start the arc to form a ball. This tungsten preparation method happens after you have set up your gun and machine, though, not before.
The most common tungsten shape to weld stainless and mild steel with is pointed, which produces a focused and stable arc, and works for all DC applications. To get this pointed shape, you’ll need a tungsten grinder or a bench grinder (a diamond wheel is best).
If you use a bench grinder, it needs to be dedicated to tungsten preparation, as you can contaminate your tungsten with anything that’s leftover on the grinder.
Press your tungsten vertically to the grinder at a 30° angle and rotate at a consistent pace until a point has formed. It’s essential to grind with the tungsten’s grain (lengthwise) and not against it (horizontal on the grinder) for a few reasons.
The main reason is that it lowers the number of ridges in the tip of the tungsten. More ridges mean that the arc has more surface to cover, increasing your chances of it wandering or the tip melting off and falling into your weld pool. Your tungsten will also stay sharper for longer if you follow the grain, so you won’t need to re-grind it as often.
A truncated tip follows the same preparation as a pointed tip but with the added step of grinding the end, so you get a flat top. This shape works well for both AC and DC applications.
For now, though, if you’ve opted for a gold or grey tipped tungsten, let’s stick with a 30° point.
When you’re TIG welding, your workpiece must be clean. If the metals you want to join are rusted, have paint on them, are oily or otherwise coated in some way, you’ll need to grind the metal until it’s squeaky clean. If you leave anything on your workpiece, your weld could be contaminated, and it won’t be a quality weld.
If you’re working with aluminium, your metal still needs to be cleaned, but you’ll need to prep it with acetone and a wire brush rather than grinding it. Aluminium is soft, so taking a grinder to it will ruin the metal before you’ve even attempted to weld it.
- Machine Settings
TIG welding requires a shielding gas to protect the weld from outside contaminants. The good news is it doesn’t matter what kind of metal you’re welding; pure argon gas alone will cover almost every TIG application, so you won’t need to swap between bottles. (You can still get gas mixtures for specific applications, however.)
TIG welding requires a flow meter so you can adjust the gas flow rate. Every UNIMIG TIG welding machine comes with the needed flow meter, which you insert into the top of your gas tank.
The flow meter has two parts: a pressure gauge and a flow tube. The pressure gauge tells you how much gas is left in the tank and the tube (which is adjusted by a valve on the side) shows you how much gas is pumping into your torch per minute.
Turn the valve so that it’s fully closed before you open your gas bottle. An 8-10L per minute gas flow is a standard amount that will cover all metal types and keep your weld safe.
2. Torch Setup
There are two different types of TIG torch that you can use. One comes with a button and one doesn’t. The type of torch that you have will determine the ways you can ignite your arc.
3 types of TIG
- Scratch start
Scratch Start is the most basic form of TIG welding and requires dragging the electrode across the surface of a workpiece to initiate the weld cycle.
- Lift Arc
Lift Arc requires touching the workpiece and lifting the torch to initiate the weld cycle.
- High Frequency
A High Frequency start allows you to initiate the weld cycle by pressing a button, or foot pedal.
If you have a High Frequency torch, you can activate it with the button (or foot control), which also controls your gas. If you have a Lift Arc torch (which comes with a valve), you are limited to lift starts and scratching (however, scratching isn’t recommended as you can cause tungsten inclusions at the beginning of your weld).
Neither scratching nor lift starting will work on AC, so you must have a High Frequency torch if you’re using AC. The VIPER 180 AC/DC TIG/Stick Welder comes with a high-performance T2 TIG Torch, which is a High Frequency torch, and if you’re a home DIY welder, you’ll want to learn with the easiest arc ignition.
There are two variations of the High Frequency torch: one with only a button and one with a button and a potentiometer (pot). The potentiometer torch gives a welder more manual control over the number of amps they’re using during a weld when the welder is set to remote mode.
You can also decide if you want a rigid head or a flex head on your torch. A rigid head means the neck won’t bend, making it harder to get into tight corners. A flex head can bend, making it a lot easier to get into tight spaces and awkward angles. The VIPER 180 AC/DC & RAZOR 200 AC/DC TIG/Stick Welder’s both come with flex head torches.
Standard torch sizes
TIG torches come in a number of sizes: 9, 17, 18 & 26. The 18 torch is the same size as the 17, but it is water-cooled rather than air-cooled. Each torch uses the same types of consumables (see below) but will have their own sizes that fit inside when it is put together.
A size 9 torch will have much smaller consumables than a size 26. The smaller the torch you purchase, the lighter it will be, but the hotter it will get at higher amps. Professional welders often prefer a lighter torch so that they can weld for longer before their hand gets fatigued.
On the flip side, the bigger the gun you get, the higher amperage it can take. A size 26 torch can use more power and stay cooler for longer than a size 9.
Regardless of the type or size of torch you have, the next thing you’ll need to do is plug it in. TIG welding is always done in negative polarity, which means that the torch goes into the Negative (–) panel mount and the earth clamp goes into the Positive (+) panel mount on the front of your welder.
If you get the polarity wrong, you can burn your tungsten up into the torch, so double-checking before you start is a good idea.
After you’ve locked your torch into place, if you have a High Frequency torch, attach the power cable plug into the socket and the gas hose into the gas connector at the front of the welder to finish your torch setup.
NOTE: if you have a water-cooling torch, you will also need to attach the blue and red water cables to the welding machine and the water cooler so that the water can flow through the torch.
The correct polarity setup is available in our User Manual that comes with each machine (and is available online), so don’t stress if you forget.
Building your TIG torch
To set up your torch you should have:
- Your chosen tungsten
- Collet body
- Back cap
- Ceramic cup (gas shroud)
The collet and collet body should match the size of your tungsten (if your tungsten is 2.4mm thick, the borehole in your collet and collet body need to be 2.4mm wide).
Your ceramic cup is marked with a number indicating how large the cup’s opening is, which will determine how much gas coverage you will get to protect the weld. They also come in a variety of materials, such as Quartz (Glass).
Quartz cups work the same way as ceramic cups, but they allow for a lot more visibility because they’re clear. Quartz cups use a gas lens rather than a collet body to achieve this additional coverage, so their shrouds are wider, which protects more of the weld while it’s liquid.
Gas lenses are an optional accessory on TIG torches which replace the collet body inside the torch. They’re especially useful when welding inside corners or in tight spaces because you can stick the tungsten out further thanks to the extra gas coverage.
Standard lens vs Gas lens
Standard nozzles release a broad plume of shielding gas over your weld. In comparison, a gas lens improves shielding gas coverage by distributing gas around the tungsten more efficiently with less turbulence. You can also have the tungsten stick out further with a gas lens, giving you better manoeuvrability and visibility of the weld pool. This is great for when you need to weld in tight spaces.
If you are using a gas lens, you’ll need a gas lens ceramic cup, as a standard one won’t fit. The below steps don’t change much if you’re using a gas lens.
- Fit the collet into the collet body.
- Fit the tungsten through the collet and collet body.
- Screw the collet body into the torch head.
- Screw the back cap onto the torch head. Don’t fully tighten just yet.
- Screw in the ceramic cup onto the front of the torch.
- Finally, adjust the tungsten to your desired length, then fully tighten the back cap.
Keep in mind that the tungsten shouldn’t stick out further than the inner width of the ceramic cup. For example, a #7 cup is 11mm wide, so the tungsten shouldn’t sit further out than 11mm from the top of the cup.
It’s okay if your tungsten is sticking out too far after you’ve screwed the back cap on; just unscrew it until the tungsten becomes loose, slide the tungsten back until it’s the correct length and then re-screw the back cap until the tungsten is snug again.
Now your torch is complete and ready for use.
3. Machine Settings
The first time you look at a TIG machine, you’re first thought might be along the lines of, ‘that’s a lot of lights and buttons’. You’d be correct. Compared to MIG and stick machines, a TIG welder can seem super complicated. Don’t stress; it’s easier than it looks. Using the RAZOR 200 AC/DC TIG Welder as a guide, let’s run through what they do.
Starting on the far left is a column of five, with the following options:
- AC PULSE
- DC PULSE
These are our welding process settings. MMA (manual metal arc) is also known as stick welding. All TIG welders can stick weld, so you would switch to that setting if you attached an electrode holder to your machine.
The other four options are what we use to TIG weld with. AC currents are used when working with aluminium, and DC is used for steel and stainless steel.
The AC and DC settings will provide a constant running current, while the PULSE options will give a pulsating current (imagine a flickering light bulb). The pulse options are often used for very precise or artistic welds on thinner material, as it does not penetrate as deeply.
Moving slightly to the right is a column of three options:
These stand for two touch, four touch and spot.
2T (two touch) means you will need to hold the button down on your High Frequency torch while you weld.
In 4T (four touch) mode, you will only need to click the button to ignite the arc and the torch will continue to weld until you click it again to turn it off.
SPOT is precisely what it says, consecutive and evenly timed arcs that work well if you want perfectly even tacks and small welds. If you’re using a foot pedal, you’ll need to set it to 2T as it won’t work otherwise, but more on that later.
Next up is the pyramid steps. These are the parameter settings and are the ones you’ll need to change when swapping between welds. In order from left to right, they are:
- Pre-gas: this is the gas that shields the tungsten and area you are about to start welding from the atmosphere. Use the knob to select how long you would like your pre-gas to flow before the arc ignites.
- Start amps: these allow for a lower or higher amp start, depending on your material. If you have a thicker piece of metal, you’ll want to start on higher amps than if you’re welding a thinner piece.
- Up slope: your up slope will dictate the amount of time (in seconds) it will take to reach your peak amps from your start amps. The more time you input, the longer it will take for the amps to increase. A longer up slope is recommended for thinner metals to prevent burning straight through.
- Peak amps: these are the amps you will do your welding on until you have finished the joint. If you are set to AC/DC pulse, this will be the high part of your amp cycle.
- Base amps: you will only use base amps in PULSE modes. This is the low part of your amp cycle. The closer your amp range from peak to base (e.g. 80 peak – 70 base), the hotter your weld will be. The more significant the gap (e.g. 100 peak – 70 base), the cooler your weld will be.
- Down slope: your down slope will dictate the time (in seconds) between your peak amps and your finish amps. This will taper the arc to prevent crater holes and cracks in the weld.
- Finish amps: this is the final amp level that the machine will reach before your arc extinguishes. If you turn this up, it will be a hotter finish, suited to thicker materials. Turning it down will provide a cooler finish suited for thinner materials.
- Post gas: this is the gas that flows for a set time once your arc has turned off, to shield and cool the tungsten as well as the weld. The longer you leave this on, the less likely you are to have pinholes and craters. The thinner the metal, the less time it needs to be on.
- AC Balance: this is automatically calibrated based on your other parameters; however, you can manually adjust it. If you set it to above 0, you will increase the cleaning but decrease the penetration, and if you set it below 0, you will decrease the cleaning and increase the penetration of the weld. (Only for AC & AC pulse.)
- AC Hertz: this is the number of times per second that the current completes a full cycle. If you turn this up, it will increase the cycle speed and create a thinner, more prominent weld appearance as the arc will be more focused. The lower you turn this, the flatter your weld will be. (Only for AC & AC pulse.)
- Pulse Hz / Pulse %: Pulse Hz is the number of times per second the current cycle will switch between peak amps and base amps. The faster the amp switches, the narrower the weld. (AC/DC pulse only.) Pulse % is the percentage of time the peak amps are on during the pulse cycle. A high percentage will have a hotter weld, and a low percentage will have a cool weld. (AC/DC pulse only.)
- Arc force / Spot: this is only for stick welding (MMA) and helps with the penetration of the stick weld; the higher this is, the more penetrative the weld. This will only be available if you have set your machine to ‘Spot’ mode and is the timer you’d like to have your arc last for during each tack or small weld.
On the right side of the adjustable knob are three lights:
These lights won’t always be illuminated, and you definitely don’t want the parameter warning light to be on.
Remote: this light will turn green if you are in remote mode. You can activate remote mode on the High Frequency torch. Turn it on by holding the button on your torch down for 5 seconds until the machine beeps and the light turns on. Remote gives you more manual control over the amps; however, a foot pedal can only be used in 2T mode, as letting go of the pedal will kill the arc.
Tungsten Electrode mm: input your tungsten width here. The machine will only provide a limited number of options, as there are only so many tungsten sizes. You can navigate to this setting with the control knob.
Parameter Warning: this light will turn yellow if you’ve put in amp settings that the machine thinks are too low for your tungsten. If you have told the welder that your tungsten is 2.4mm and then set your peak amps to 40, this light will come on to let you know that you’re going to have a weak arc.
Mixed Arc AC/DC Welding
Mixed AC/DC welding is the combination of TIG AC and TIG DC- in one weld. There are quite a few benefits from this type of weld, including higher welding speeds and penetration, and a faster weld puddle on cold workpieces. Mixed AC/DC also means that you can weld on thicker materials.
There are two periods during a mixed weld. The first is the AC period, where the oxide film is broken and surface impurities are flushed out. Second, the DC- period, where the arc becomes narrower and penetrative. The operator can select the percentage of AC and DC- during a full period, which can be varied from 5-95%, though it’s a good idea not to have more than 50% DC-.
This feature is pretty specialised, and only the RAZOR 320 AC/DC TIG/Stick Welder has this option available on UNIMIG machines.
The second part of TIG welding is your filler rod – the metal you’ll be using to feed into the weld pool. You need to match your filler rod metal to your parent metal, as dissimilar metals only weld together if you have the right filler. These rods usually come in 50cm or 1m lengths, so it’s a good idea to cut them down to a comfortable size as it’ll make it easier to feed.
There are a few different classifications for each type of filler rod available.
- ER70S-2: best quality and most common
Stainless Steel Rods:
- 308L: mainly used on austenitic stainless steels
- 309L: used for welding dissimilar metals
- 316L: marine grade, recommended for anything that will be used in water, will only weld to 316 graded parent metal
The ‘L’ refers to the extra low levels of carbon in the rods, which helps prevent corrosion in the welds.
- 4043: use on 4000 to 6000 series aluminium, contains silicon
- 5356: use on 3000, 5000 & 6000 series aluminium, marine grade, contains magnesium
Just like with your tungsten, you want your filler rod size to fit your workpiece size. A good rule of thumb here is to match your rod size to the tungsten. Let’s use an example: 3mm steel. You’ll be using a 1.6mm tungsten on this metal thickness, so a 1.6mm filler rod will be perfect.
Starting Your Weld
Once your equipment is all set up, you’re ready for the fun part: starting a weld.
Three main factors need to be considered when doing a weld:
- Work angle
- Travel angle & distance
- Travel speed
This is true regardless of whether you are TIG, MIG or stick welding.
1. Work Angle
Your work angle is your torch position in relation to the angle of the joint. There are a few different joint types, and several positions these joints can be found.
|T-joint / Fillet Joint||Butt Joint||Lap Joint|
|90° joint angle||180° joint angle||90° joint angle|
|45° work angle||90° work angle||60°/70° work angle|
(These angles do not include your travel angle, which we’ll talk about next.)
|Flat (butt & fillet)||Horizontal||Vertical||Overhead (butt & fillet)|
The main thing that your weld’s position will affect is whether or not you’ll be fighting against gravity as you go. While you’re learning, flat positions are best.
2. Travel Angle & Distance
TIG welding is always done at a push angle. A push angle means your torch is over the weld, and you push the weld pool along the joint. Dragging (pulling) while TIG welding won’t penetrate or properly cover your weld, resulting in porosity in the joint as the gas from your cup won’t reach the liquified metal.
You also want to keep your torch at a 75° angle as you push. If you’re welding in a fillet joint (a corner join), your torch will be angled into it at a 45° angle, then you’ll angle slightly to the side so that your gas can cover the weld pool and in front of the weld as you go.
The filler wire will be in whichever hand is not holding your torch. Your filler wire should come in from relatively low, almost parallel with the joint, with a slight 10° to 15° angle (back end in the air) when it is introduced.
The distance between the tungsten and the weld is also something you need to watch as you go about your weld. The best length to keep your tungsten from the workpiece is around 3mm. This will give you the best control over the arc and your weld. It also gives you space so that the filler rod is unlikely to touch the tungsten.
If your torch is angled too far or is too far away from your workpiece (creating a long and unstable arc), you will likely have a weld with much more oxidation. The filler wire also won’t melt into the joint because there’ll be a lack of heat.
If your tungsten touches the weld pool, then you’ll have to stop the weld and re-grind the tungsten. If you do touch your tungsten into the weld pool, don’t try to snap it off. Turn your torch off without moving it and allow it to cool slightly. Then you can loosen the back cap of the torch and simply slide the tungsten out. This way, you don’t risk damaging the collet body inside your torch.
Travel speed is how fast you are moving the torch along the weld. The speed you travel affects how far the weld penetrates. Too fast, and it won’t go far enough, too slow, and you could burn a hole straight through. Your travel speed also dictates the weld’s conformity; if you’re speeding up or slowing down, then the weld won’t be even.
Keep your travel speed consistent! This applies to all types of welding. Inconsistent travel speed or incorrect travel speed will result in a bad weld.
Making the Weld
Place your cleaned workpiece in front of you in a way that when you begin welding, your hands can move freely and steadily, and you can comfortably complete the joint. It’s a good idea to have something to steady your hands against as they go along the weld so that you can maintain your angle and distance.
Check that your earth clamp has been attached to a metal surface, such as a (clean) metal workbench or the workpiece, because if your earth clamp isn’t grounded, your machine won’t start. If you’re making a fillet join, you can use a magnetic welding clamp to hold your two pieces of metal together. Aluminium isn’t magnetic, however, so a manual clamp will be needed.
Start with your tacks. Remember to flip your welding helmet down before you ignite your arc. Tacks are used to fuse the metals together at the edges, so you don’t have to hold them together while you’re trying to weld. This is especially important when TIG welding as you don’t have any free hands.
Hold your torch in your dominant hand and your filler rod in your other hand. Press the button on your torch to start the arc (keeping pressure on it in 2T mode) until you see a wet pool forming. Dab a small bit of filler rod into this pool and then release your button. You’ve just made your first tack.
Repeat this process on both edges so that your workpiece stays lined up how you want it. If the metal you’re welding is completely flush, and there is no gap at all at the join, you can get away with just fusing the two pieces together with the torch for your tacks. With your tacks done, you can remove the magnetic clamp.
To make the weld, start the same way as you did to make the tack. Press the button (holding it down if you need to) until the metal begins to pool. Then dab the filler wire into the leading edge of the weld pool. You don’t want to touch it onto the tungsten in the middle of the arc. You are aiming to push the filler wire into your pool to make the best weld.
When adding filler wire, a good rule of thumb is to add the same amount on each dab as the wire’s width. For example, if your wire rod is 1.6mm in diameter, you want to add about 1.5mm of the rod into each dab. Also, make sure you’re feeding the filler rod into the pool in sections rather than constantly holding it in. Take pauses between each dab to let your weld pool reform.
Once you’ve run your weld, release the button, and the torch will cool down and then pump your post gas out over your weld. Having this ‘post flow’ over your weld as it cools will help to keep it free of contaminants, but you’ll need to remember to keep your torch over the weld for this to work. It’s super tempting to pull your hands away immediately to check out your weld, but you’ll lose your post flow if you do.
Congrats, your weld is done, and you can now take a look at your handiwork. A good TIG weld should look like an even and straight stack of dimes with no porosity or other signs of contamination when you’re done.
Fusion welding follows the same process as previously described, except you don’t add any extra metal. This is nowhere near as strong as a standard weld, and so it’s best to use it for practice only. It’s a great way to get a feel of the TIG torch while you’re still learning, and you can fusion weld on your scrap metal to practice creating consistently sized weld pools and running beads.
If you’re going to be welding on piping or tubing, then it’s a good idea to back purge as you go. Back purging is the process of shielding the back of your weld from carbide precipitation (your metal reacting to the atmosphere).
If you don’t shield the inside of your pipe, the weld’s backside will look like it’s covered in granules (which is why this is called ‘sugaring’), and it means your weld will be prone to cracking. In simple terms: it’s a failed weld.
To back purge, first, you’ll need an extra gas tank, or a dual regulator, as you need to pump gas to your torch and into the pipe at the same time, but at different flow rates, which requires two hoses.
Plug up the ends of your pipe – you can get specifically designed purging plugs for this – or tin foil works as well if you’re on a budget (glad wrap doesn’t work, it’s too weak to hold the gas in).
It’s essential to make sure you have a ventilation hole on either end, as you need to insert your gas hose in one side and have an exit hole for the atmospheric gas to escape. If you don’t leave a vent hole, the gas will make its own as you reach the last part of your weld and it becomes trapped.
If you’ve purged correctly, your weld should be smooth inside and look similar to the outside weld. This can take a bit of fiddling with because your pipe size and the material will determine how much gas you need to be pumping in to cover the weld fully. There’s no one size fits all rule with this.
The best way to get better at something is to practice, practice, practice! You can make dry runs as many times as you need to feel comfortable with the motion before starting an actual weld.
If you’ve got some spare or scrap metal, you can practice making beads on the parent metal (make a weld pool, push it along the metal at a steady pace, repeat) without adding any filler metal (fusion) to practice the torch motion and to get a feel for how long it takes for the pool to form each time.
Once you’ve got the hang of making a clean, quality TIG weld, you can play around with the gas and other settings to make more colourful and artistic welds.