How to TIG Weld

Everything You Need To Know About TIG Welding

By Ron Covell   –   Photography By the Author

We’ve covered MIG welding, which for many years has been the most widely used process for both amateur and professional car builders. Since MIG welds are strong and fast, and the learning curve is easy to master, why would you consider anything else? That’s exactly what we’ll cover in the basics of TIG welding.

02 the filler material is manually added with the other when TIG welding
When TIG welding, the torch is held in one hand and the filler material is manually added with the other.
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MIG Vs TIG Welding

Fundamentally, it comes down to the degree of control that TIG welding offers, and the broader spectrum of metals it is suited for. MIG is used primarily for carbon steel and stainless steel, and certain MIG welding machines can be equipped to weld aluminum, but the TIG process works with virtually any weldable metal. There may be times when you need to weld magnesium, copper, bronze, titanium, or Inconel, and the TIG process is well suited for all of these—and more.

Read More: How to MIG Weld

03 TIG welds are so clean is because the weld is shielded with an inert gas
One of the reasons that TIG welds are so clean is because the weld is shielded with an inert gas—usually Argon.
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Having more control over each parameter of the welding process also makes it easier to get the dime-on-dime look that many builders prize. It can also help with getting sufficient penetration in challenging situations, and to tailor the welding arc to make it ideal for any weld joint configuration and for a broad range of material thicknesses.

04 Youll have to experiment to find the proper gas flow
You’ll have to experiment to find the proper gas flow, and it’s influenced by the cup size and the kind of material you’re welding. A good place to start is 14 cubic feet per hour (CFH) for mild steel.

Inert Gas

One key difference between MIG and TIG is how the filler wire is added to the weld. With MIG welding, the wire feeds automatically whenever the trigger on the gun is pulled, and if shielding gas is used the gas flow is started and stopped with the trigger, too. With TIG welding, the torch has a non-consumable tungsten electrode that the arc emanates from. The arc is normally started and terminated with a foot or hand control, which also starts and stops the flow of the shielding gas. Many machines allow you to set both pre and post flow of the gas, which helps prevent the electrode and base metal from oxidizing.

05 The torch is fitted with a ceramic cup which guides the flow of the shielding gas
The torch is fitted with a ceramic cup, which guides the flow of the shielding gas. Many sizes are available. There is a non-consumable tungsten electrode inside the cup, and the arc (and welding heat) streams from this electrode.

TIG welding is always shielded with an inert gas (usually argon), and if filler rod is used, it is added by hand. Feeding the right amount of filler rod, at just the right time, into just the right place, is a skill that takes time to master, and this is one of many factors that makes TIG welding more challenging to become proficient with.

06 Most TIG welders supply both alternating current AC which is used for aluminum and magnesium and direct current DC for all other metals
Most TIG welders supply both alternating current (AC), which is used for aluminum and magnesium, and direct current (DC), for all other metals. There is usually a button or switch to toggle between these functions.
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Amperage Control

TIG welding machines have a control for amperage, which is essentially the amount of heat that goes into the workpiece. On the most basic, entry-level welding machines the amperage is controlled solely by a dial on the face panel, but I strongly recommend stepping up to a machine that has a foot (or hand) control, allowing you to use any portion of the maximum value set on the face panel. There are many reasons why you may want to change the heat “on the fly.” Often you will need a large amount of heat to establish a weld puddle when the metal starts at room temperature, and once you have welded an inch or so you will notice that the base metal is building up heat, so less heat from the torch is needed to keep the puddle the ideal size. As you reach the end of a weld seam the heat at the weld tends to build up more rapidly, and you may need to decrease the heat even further. This is easy with a foot or hand control, but you run the risk of making welds that start too cold and end too hot if your machine doesn’t have this capability.

07 A dial on the face panel of the machine is used to control the amperage
A dial on the face panel of the machine is used to control the amperage (heat). The rule of thumb is to use one amp for every 1/1000 inch thickness of the metal you’re welding. For example, welding 1/8-inch material will require about 125 amps.

Welding Arc Differences and Filler Rod

One of the things people really appreciate about TIG welding is the smoothness and cleanliness of the welding arc. MIG welding always throws out a shower of sparks, but TIG welding only sparks on rare occasions—usually when there is some impurity in the weld zone. The other side of this is that TIG welding requires that the base metal and the filler rod be squeaky-clean, while MIG welding can tolerate a certain amount of surface contamination.

08 The most basic machines do not provide an adjustment for amperage as you are welding
A foot pedal is often used to adjust the amperage as you are welding, but some people prefer a hand control. The most basic machines do not provide an adjustment for amperage as you are welding, but it’s a highly desirable feature.

Read More: The Metalwork Behind The GNRS 2022 Al Slonaker Award Winning Highboy Coupe

The More Higher-end TIG machines give you advanced functions, like waveform controls and pulsing. These are beyond the scope of this introductory article, and most car builders don’t really require them, but they do make certain challenging welding situations easier to manage—like welding extremely thin or delicate materials, for example. MR

09 when welding is to move the torch and filler rod with precision
One of the most important things when welding is to move the torch and filler rod with precision. It is often helpful to use blocks or other supports to steady your hands.
10 Its very important to keep the tip of the tungsten electrode close to the workpiec
It’s very important to keep the tip of the tungsten electrode close to the workpiece—maintaining an 1/8-inch gap is a good target to shoot for.
11 If you accidentally let the electrode touch the puddle it often gets contaminated
If you accidentally let the electrode touch the puddle, it often gets contaminated. It is essential to regrind the electrode before continuing.
12 The angle ground on the tip of the tungsten affects the width of the arc cone
The angle ground on the tip of the tungsten affects the width of the arc cone and the size of the puddle. A 30-degree included angle is a good starting place.
13 One nice feature of TIG welding is that it does not generate a shower of sparks
One nice feature of TIG welding is that it does not generate a shower of sparks, like MIG or stick welding.
14 Another great benefit of the TIG process is the ability to join virtually any weldable metal
Another great benefit of the TIG process is the ability to join virtually any weldable metal, including exotics like magnesium and titanium.
15 TIG welding is not very tolerant of surface contamination
TIG welding is not very tolerant of surface contamination, so it’s important to thoroughly clean all surfaces before welding, including the rod.
16 For most welding the torch is held at about 75 degrees from the work and pointed in the direction of travel
For most welding, the torch is held at about 75 degrees from the work and pointed in the direction of travel. The rod is held about 15 degrees from the work.
17 Filler wire is available in many different alloys and diameters
Filler wire is available in many different alloys and diameters. It’s important to select an alloy that’s compatible with what you’re welding. For materials up to 1/8 inch, the rod diameter should be close to the material thickness.
18 One of the great benefits of the TIG process is having fine control of all the welding parameters
One of the great benefits of the TIG process is having fine control of all the welding parameters, allowing a skilled operator to make welds with the prized dime-on-dime profile.
19 Having fine amperage control also makes it possible to weld very thin materials
Having fine amperage control also makes it possible to weld very thin materials, like these razor blades.
20 Good welding is all about heat control
Good welding is all about heat control. The far weld does not have enough heat–the bead stands proud of the surface. The near bead is too hot–there is no weld definition. The middle bead has the proper amount of heat and is a good example of what to shoot for.

Source
Miller Electric Manufacturing Co.
(920) 734-9821
millerwelds.com

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