Heliarc®/TIG Welding Overview
What is TIG Welding?
TIG Welding is a manual welding process that requires the welder to use two hands to weld. What separates TIG welding from most other welding
processes is the way the arc is created and how the filler metal is added. When TIG Welding one hand is used for holding the TIG torch that
produces the arc and the other hand is to add the filler metal to the weld joint. Because two hands are required to weld; TIG welding is the
most difficult of the processes to learn, but at the same time is the most versatile when it comes to different metals. This process is slow
but when done right it produces the highest quality weld! TIG welding is mostly used for critical weld joints, welding metals other than common
steel, and where precise, small welds are needed.
|TIG Welding Process
||TIG Welding Torch
||Finished TIG Weld
TIG Welding Names
Knowing alternative names and abbreviations for TIG welding is important for architects reading and/or writing specifications. As of today TIG
welding is the most common term that is widely accepted and used. TIG stands for Tungsten Inert Gas Welding.
TIG welding's proper name is Gas Tungsten Arc Welding or "GTAW". This is the name the American Welding Society and other welding organizations
refer to this process on their welding procedures. GTAW is also the abbreviation that welding engineers use to specify the welding process that
is to be used on blue prints. When TIG welding was introduced around the 1940’s Helium gas was the primary shielding gas used in process. The
term Heliarc welding was the common phrase used back in the day and now is a registered trademark “GENUINE HELIARC”, it now owned by ESAB welding
equipment. Most veteran welders refer to TIG welding as Heliarc welding. When someone refers to TIG welding as Heliarc, it’s pretty safe to
assume either they have a lot of experience, or apprenticed under a journeyman welder who has been around. Although the Heliarc name used to
refer to the use of Helium only, as the inert gas, Argon has largely replaced it. Helium is still used, but more now as part of a two Part mixture
along with Argon when a deeper weld penetration is needed.
Why Tungsten is used to Weld
Tungsten Welding Rod
Since the name includes the term “Tungsten” and tungsten is what makes TIG welding possible, it is good to know what tungsten is. Tungsten is
a very hard, slightly radioactive, and brittle metal. Its uses are limited compared to other metals. In TIG welding the tungsten is made into
a non consumable electrode that is used to create the arc for TIG welding. Typical other uses for tungsten are in light bulbs,
heating elements, and rocket engines. Basically any place that requires a very high melting point or the need to pass electricity at
a high temperature is needed. In the case of TIG welding the tungsten metal properties allows an arc to maintain a temperature up to 11,000
degrees Fahrenheit. A high melting point and excellent electrical conductivity keeps the tungsten electrode from burning up. The unique properties
of tungsten allow welding with a hotter arc then the actual melting point of the tungsten. The tensile strength of tungsten is extremely high
at up to 500,000 lb per square inch. When comparing it to commonly used steel, with 36,000 lb of tensile strength per square inch, tungsten
is far stronger. Although the metal is very strong it is also brittle. It is not hard to break a tungsten electrode with just a tap of a hammer.
How TIG Welding Works
TIG welding requires three things, heat, shielding, and filler metal. The heat is produced by electricity passing through the tungsten electrode
by creating an arc to the metal. The shielding comes from a compressed bottle of gas that flows to the weld area to protect it from air. The
filler metal is just a wire that is dipped by hand into the arc and melted. The way these three things come together is pretty simple. First
the welder turns on the gas flow, many times by a valve on the TIG torch itself. The gas begins to flow and starts protecting the weld area
from the air. The torch is held over the weld joint just far enough for the torch not to touch the metal. Then the welder presses a foot pedal
and the TIG torches tungsten electrode starts an arc. Once the arc is started the two pieces of metal begin to melt by creating a puddle of
metal. Once the puddle is established the welder with the other hand starts filling the joint by manually dipping a welding wire into the arc
to fill the joint. Ultimately this process creates a single piece of metal.
TIG Power Supplies
TIG welding power supplies are usually Stick welding power supplies. The main difference between SMAW welding power supply and TIG power supply
are the bells and whistles TIG welding sometimes requires. A basic TIG torch can be added to a Stick welding power supply and it will weld fine.
Both power supplies are constant amperage power supplies. Meaning they keep the amperage consistent and the heat settings are regulated in amperage.
The voltage on these power supplies will vary depending on the length of the arc.
TIG Welding Aluminum
When TIG Welding aluminum, there are a few steps required to setup for it. First is the tungsten. The tungsten needs to be either pure Tungsten
or Zirconium Tungsten. The tungsten also needs a ball shape at the end of the rod to spread the heat properly. The second is the current type
and that is aluminum always welds with A/C (alternating current). Welding aluminum always requires a high frequency start from either a high
production button or a foot pedal operated TIG torch. The main difference when welding aluminum verses other metals is how the puddle looks.
Aluminum has a shiny puddle that does not glow. It looks like tinfoil moving. When welding aluminum, overheating of the metal must be avoided.
It’s real easy to keep welding and all of a sudden the whole weld area just drops to the floor.
TIG Welding Anodized Aluminum
When TIG welding small diameter thin gage aluminum, many people like to use a high production button. The purpose for the button is to bump
the weld. What that means is basically spot welding the area to be welded. This technique is typically used to weld anodized aluminum. In the
skylight industry many architects and/or customers specify anodized aluminum to protect the aluminum from corrosion. Anodized aluminum has a
coating that makes it difficult to weld. Welding anodized aluminum requires two steps. The first step is to spot weld the area to be joined
and add filler wire. This weld is less then acceptable looking because the anodized coating has not melted properly. The second step is to spot
or bump weld around the same weld without adding filler wire. This does is melts the anodized coating into the weld. After that the weld is
painted with weld paint to protect it from corrosion.