By: Weld.com Crew on June 3rd, 2019

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TIG Welding 101: An Introduction to Gas Tungsten Arc Welding

TIG Welding 101

 

Gas Tungsten Arc Welding, more commonly referred to as TIG Welding is one of the most difficult processes to master. It's also one of the most in demand. and highest paying skills you can have in welding. 

Today we're going to take you step-by-step through the basics of TIG welding. You'll learn how to setup your equipment, what machine parameters do and welding technique.

ADVANTAGES OF TIG WELDING

Before we dive into the ins and outs of setting up your TIG machine, lets first talk about why TIG welding would be chosen as opposed to other, quicker processes.

Precision

The reason TIG welding is the most used process in aerospace, racing, and nuclear power is because it is far more precise than other portable processes. TIG allows the operator to control the amount of heat going into the part with a variable amp controller. The ability to weld as low as 1 amp, makes this process unlike any other.

Weld Any Material

Other processes are limited in what materials they can weld. For example, you can't stick weld copper. You can't MIG weld Titanium.  You can't flux core weld Aluminum. With TIG, you can weld any material. on the planet, as long as it's weldable.

Weld Cleanliness

TIG is an extremely clean process. There is no spatter, no flux, no smoke and nothing that needs to be cleaned up. after the weld is completed.

No Need for Multiple Gas Types

Some processes, like MIG, require multiple gasses to be in the shop. A mix of 75% Argon and 25% CO2 is common for most short circuit processes, while higher Argon mixes are needed for spray transfer. In TIG welding, 100% Argon is used in for almost everything. In rare cases helium can be introduced hot.  hotter weld applications.

All Positions

TIG welding can be done in all positions. Unlike stick, is doesn't matter what electrode you're using,  TIG can always go in any position.

DIsADVANTAGES OF TIG WELDING

Weld Speed

TIG is a slow, meticulous process. Even when performed by. experienced professionals, it is a much slower process than its MIG and Stick counterparts.

Wind

Because TIG welding uses shielding gas to protect the molten weld pool, it is very susceptible to wind. Any disturbance in the shielding gas will result in weld porosity and Tungsten contamination.

Cost of Entry

When compared to other processes, TIG power sources have traditionally been more expensive. However, with the quality of import machines rising, TIG is now more accessible.

 

Equipment SETUP

There are 6 key components to any TIG setup. Let's take a look at each and how they go together.

Power source

Before you do anything it's important to make sure your power source is unplugged and in the off position. Having your power source plugged in while connecting everything can result in electric shock to the operator or damage to the machine. Once you ensure your power source is off, it's time to setup the accessories.

TIG Torch

There are several different styles of torches that will suit different applications. Most field work use an air cooled torch, while most production work uses an air cooled torch.

Air Cooled Torch

An air cooled torch, like the one used in this video, uses Argon shielding gas to cool the power cable.

Water Cooled Torch

Water cooled torches employ a separate water cooler that runs cold water up to the torch head and send the hot water back to the cooler.

The TIG welding process is performed in DCEN (Direct Current Electrode Negative). The  electrode is the Tungsten that is inside the torch, so that means the torch will be plugged into the negative terminal (-).

 

Ground Cable

The ground cable will always be plugged into the positive terminal on the power source. Attach the front end of your ground clamp as close to the work piece as possible.

Gas Cylinder

There are a few things to remember before connecting your gas source.

1. Proper Transit

Gas cylinders can be extremely dangerous if not respected in a shop environment. When you're moving any cylinder, make sure that the cover is properly installed. A cylinder falling without a cover could result in the valve stem breaking and causing an explosion or turning the cylinder into a projectile.

2. Chain up your Cylinder

Whenever the cylinder is in place, chain it to a wall, table or welding cart where it's secure.

3. Remove Debris

Before you can hook up the regulator you'll need to remove any debris from threads in the valve stem. Stand to the side of the valve and simple give it a quick blast to push any foreign material out of the threads.

Regulator

Once the cylinder is safely chained up and the threads have been blown clean it's time to install your regulator.  The regulator will tell you two very important things:

1. How much gas is left in the cylinder, and;

2. The flow rate of gas coming through your torch

Connect the regulator by threading it directly into the threads on the cylinder's valve. Don't use products like teflon tape. You don't need it because the threads are brass and will seal without any assistance. Another reason teflon tape is a bad idea is because teflon is a petroleum product, which is highly flammable.

Gas Hose

Most regulators these days come with a gas hose. If yours doesn't they can be picked up cheap at your local welding supply house or online.  Connect one end of the hose to the regulator and the other end to the power source's gas inlet. Use a wrench just to snug up the fittings. Don't tighten them too hard or you'll strip the brass threads.

Foot Pedal

A foot pedal is not essential to every TIG setup, but if you're in a shop environment,  you'll almost certainly have one. The foot pedal plugs into the remote amphenol. This will allow you variable control over your amperage while you're welding. 

Once you have all your accessories connected, it's time to plug in the machine and turn it on. Depending on the specific capabilities of your machine, there could potentially be dozens of different settings. Don't get overwhelmed! There is really only one setting you need to know starting out; amperage. The good news is, setting amperage on a TIG setup is very easy. All you need to know is 1 amp per .001" material thickness. So if you're welding on 1/8" (.125) material you'll need about 125 amps to weld it.

We're not going to dive deep into the other settings right now, but here are some common settings your machine may have and what they do:

Pulse Mode

Pulse welding will automatically pulse the arc between a high and low amperage. Think of this as a strobing effect of your arc. The purpose of pulse. welding is to get better penetration with less. heat input.

AC Mode

Alternating Current is needed if you want to TIG weld Aluminum. Aluminum has a thin oxide layer that melts at a much higher temperature than the base metal below. AC allows the DCEP side of. the wave to clean off the oxide, while the DCEN side of the wave penetrates into the material.

Upslope

If you aren't using a foot pedal, you can use upslope to raise your amperage slowly when you initiate the arc.

Downslope

Downslope is the. exact opposite. of. upslope. If you don't. have. variable amperage control you can use downslope to mimic the action of slowly releasing the pedal at the end of your weld.

Tig welding technique

Before we talk about what to look for under the hood, let's talk about how to hold the torch. This is really a personal choice. What feels comfortable to you? You want to make sure you can hold it steady, while being able to maneuver it if you need to. For most precision work, holding it like a pencil is a good technique. Once you start walking the cup on pipe there are some other techniques you can do, but for now, grip it like a pencil.

Now that you know how to hold the torch, it's time to strike an arc. In TIG welding there are a few. different ways to do this. It will depend on your machine and your settings, but here are the three ways:

High Frequency Start

High frequency is the easiest and safest way if you have the option. You simply get your tungsten close to the workpiece, without touching it, hit the pedal and the arc will jump to the plate. This means there is no chance for Tungsten inclusions in the start of the weld.

Scratch Start

Scratch start is the most frequently used method in the field. This is very much like stick welding, where the torch is always electrically hot. You scratch the tungsten across the workpiece, like a match, to initiate the weld. Because the tungsten is hot when it touches the workpiece, there is high chance of Tungsten being left in the start of the weld.

Lift Arc

Lift arc is a hybrid between High Frequency and Scratch start. You still have to touch  the Tungsten to the material to initiate an arc, but the tungsten isn't hot until you hit the foot pedal. Most people hit the pedal, rock the torch on its cup, initiate the arc and pull back up.

Once you strike an arc, push down on the foot pedal until you start to see the base metal melt. Once that molten pool forms, add filler metal to the front of the front edge of the puddle. Adding to the front edge is very important. If you try to add your filler to the center of the puddle, your arc will melt the filler before it enters the pool. You want the molten weld pool to melt your filler, not your arc. The common question that beginners ask is,

How much filler metal should I add?

The answer is simple. If you're using 1/8" filler metal, add 1/8" per dab. If you're using 3/32" filler, add 3/32" per dab. 

You'll find it's very difficult to add filler metal when you're first learning to TIG weld. Once you master adding filler, TIG welding will become second nature. 

TIG is difficult to learn, but once you master it, you'll never go back. Don't forget to share your progress with us and let us know what other videos you want to see on Weld.com.