TIG, Tungsten inert Gas, where the Tungsten is the material of which the electrode is
made of and the Inert gas is the gas coming out of the torch's nozzle, commonly Argon.
The lens, the pink piece at the end of the gun that add a much needed feminine touch
to an overly masculine design, can have different shapes and it affects the way the gas is dispensed
onto the weld and the amount needed to shield it properly.
Here's how it works: the electrode is charged with enough voltage to create an arch with
the part and enough amperage to create the heat necessary to melt the parts that need
to be welded together.
Once you have created a little pool of molten metal we can start adding the metal filler
to fill up the space between the two parts and strengthen the joint. You do need to get
into the right rhythm, you add the filler and you spread it with the torch. If you get
it right you'll get the sought after stacked coin look, typical of this welding technique.
To join two thicker pieces it is ideal to bevel the edges to form a v shaped gap between
the pieces to ensure a deep penetration of the weld. If needed more passages can be overlapped
to achieve full filling of the gap.
But why the gas you might ask, well the inert gas is there to protect the molten metal from
contacting the oxygen that would cause oxidation and result into a weak weld.
An AC DC TIG welder is best suited for aluminum welding
when exposed to oxygen the Aluminium forms an oxide layer
that melts at a much higher temperature than the aluminum itself
3600 degrees Fahrenheit vs the 1200 degrees Fahrenheit of the base material.
To solve this problem AC welding has two cycles: during the first cycle, called EP or Electropositive,
where current flows from the workpiece to the electrode, the aluminum oxide is blasted
off the surface, creating a clean area. during the second cycle, called EM or Electron
Negative, where the current flows from the electrode to the work, the arch produces enough
heat to melt the clean aluminum and fuse the joint.
The two cycles combine the cleaning stage to the welding one.
Let's take a look at a couple of controls we can find on a TIG welder
The pulser allows the operator to keep the temperature of the work piece in check alternating
between two amperage values, the maximum and the minimum.
He can decide the frequency of the switches... and the percentage of the time of one phase
over the other. All this to try to keep the work piece at
the ideal temperature.
Then we have the post flow settings, it determines for how many seconds the flow of gas will
remain active after the arch is shut off. This is done so that the weld can be protected
from oxygen contamination long enough for it to cool off.