What Is A Tig Welder

What Is A Tig Welder - Tungsten Inert Gas (TIG) welding also referred to by the name of Gas Tungsten Arc Welding (GTAW) is an arc welding technique that results in the creation of a weld using an un-consumable tungsten electrode.

What Is A Tig Welder

Tungsten inert gas (TIG) welding was an instant success in the 1940s, for joining aluminum and magnesium. 

Utilizing TIG as an inert gas barrier instead an slag to shield the weld pool from damage, the procedure offered a stunning alternative for manual and gas welding. 

TIG has played a significant part in the acceptance of aluminum in superior quality welds and for structural purposes.


Process features

When using the TIG welding process, an plasma is formed between the tungsten electrode pointed towards the workpiece within an inert environment of argon or Helium. 

The small, intense arc created by the electrode pointed is perfect for high-quality and precise welding.

Since the electrode isn't consumed when welding and the TIG welder is not required to regulate the amount of heat that is absorbed through the arc since the metal is deposited by an electrode that is melting. 

If filler metal is required it is added in a separate manner into the pool of weld.


Source of power

TIG welding should be performed by a drooping constant current source of power - whether AC or DC.

A constant current source of power is necessary to prevent excessively high currents drawn when the electrode gets connected to the workpiece's surface. 

This can happen intentionally when the arc is starting or accidentally while welding. 

When, for example, in MIG welding the use of the power source is flat and characteristic is employed when welding, any contact with the surface of the workpiece could cause damage to the electrode's tip or cause it to fuse to the surface of the workpiece. 

In DC as the the arc heat is distributed around one-third on the cathode (negative) and the other two-thirds are at the anode (positive) The electrode is always polarized negative to avoid melting and overheating. 

But, the alternate power source connection DC electrodes with positive polarity is advantageous in that once the cathode has been placed placed on the piece of workpiece, it is free of oxide particles. 

Because of this, AC is employed to weld materials with an incredibly tenacious oxide film on the surface like aluminum.


Arc beginning

The welding arc may be initiated by scratching on the surface, making a short circuit. 

It is only after the short-circuit breaks when the primary welding voltage starts to flow. 

There is however an opportunity that the electrode could be stuck to the surface and create an inclusion of tungsten in the welding. 

This can be avoided with the 'lift-arc method, where the short-circuit can be formed with a very low current. 

The most popular method of beginning an TIG arc is using the HF (High Frequency). 

The HF is composed of high voltage sparks that range from a few thousand volts, which last for only a few milliseconds. 

The HF-generated sparks can cause the electrode and workpiece gap to fall down or ionize. 

When an electron/ion cloud has formed, the current can flow out of the source of power.

Important: Since HF produces abnormally high electromagnetic emissions (EM) welding, welders must be aware of the fact that their use could cause interference, particularly within electronic components.

Since EM emission is in the air, similar to radio waves or transmitted through the power cable, great care should be taken to ensure that there is no disturbance to control equipment as well as instruments near to welding.

It is also crucial in stabilizing the AC arc. 

In AC the electrode's polarity is reversed around 50 times per second which causes the arc to cease to exist every time polarity changes. 

In order to ensure the arc renewed at every reversal of the polarity of the electrode, HF sparks are produced in the gap between the electrode and the workpiece. 

These sparks coincide with the start of every half-cycle.


Electrodes

Electrodes used in DC welding are typically pure tungsten, with 1 up to 4 percent thoria to increase the arc's ignition. 

Alternate additives are lanthanum dioxide and cerium oxide that claim to offer greater performance (arc beginning and less use of the electrode). 

It is crucial to choose the appropriate electrode tip angle and diameter for the welding power. 

In general, the less current, the smaller the electrode's diameter as well as tip angle. 

When it comes to AC welding, because the electrode is operating at a greater temperature, tungsten that has zirconia is added to stop erosion of electrodes. 

It is worth noting that because of the massive quantity of heat produced at an electrode becomes difficult to keep a pointed edge and at the same time, the electrode is shaped into the shape of a ball or spherical shape.


Shielding gas

The gas used to shield is chosen in accordance with the material to be weld. 

These guidelines can be helpful:

Argon is the most frequently-used gas to shield, it is suitable for welding many different materials, including aluminum, stainless steel and titanium.

Argon + 2-5% H2 - adding the hydrogen to argon can reduce the gas slightly which will result in better-looking welding without oxide on the surface. 

Since the arc gets hotter and more constrained, it permits faster weld speeds. 

There are some disadvantages, such as the possibility of cracking hydrogen in carbon steels, and the risk of welding metal porosity in aluminum alloys.

Helium and helium/argon combinations including argon and helium increases your arc's temperature.

This results in faster welding speeds and more effective weld penetration. 

One of the disadvantages of using helium or a mixture of helium and argon is the cost of gas as well as the difficulty getting the arc started.


Applications

TIG welding can be found throughout the industrial sector, but is particularly suited for welding of high-quality. 

Manual welding is a tiny arc is suitable for thin sheet materials as well as the controlled the penetration (in the root of pipe welding). 

Since deposition rates can be extremely low (using the separate rod for filling) MMA or MIG may be preferred for more dense materials and filling passes in pipes with thick walls welding.

TIG welding is widely employed in mechanised systems by itself or through filler wire. 

However, a variety of off-the-shelf devices are made available for the orbital welding of pipes utilized in the manufacturing of boilers or chemical plants. 

These systems do not require any manipulation skills, however the operator should be educated. 

Since the welder has little control over arc and weld pool performance, great care should be given for edge prep (machined rather than hand-crafted) as well as joint fit-up along with control of the welding parameters.

Iklan Atas Artikel

Iklan Tengah Artikel 1

Iklan Tengah Artikel 2

Iklan Bawah Artikel