If you are looking for a script where all the necessary details about TIG welding is carefully explained, you have come to a right place.
In this article, you will be informed comprehensively about how TIG welds aluminum.
What is TIG welding?
It is simply a welding process that requires a non-consumable tungsten electrode, a shielding gas(like Argon) and a surface that is free from oxide buildup and other impurities.
Things needed to be done before welding Aluminum?
Before trying to cleanse oxide build-up, make
sure before that, any kind of impurity, like dirt, grease etc, is removed completely. If any portion of dirt remains in the workpiece before you start cleansing it from oxide impurities, it would be highly harmful to the health of your welding process. Because these impurities burn easily in the process as a result get trapped into the oxide layers thus making the weld of aluminum undesirable.
For TIG weld of aluminum, one of the best ways to remove these impurities is by using a MICROFIBER cloth soaked in solvents such as Butanol, acetone or paint thinner.
How to remove an oxide build-up?
One method involves a Mechanical Approach and the other one makes use of an Electric Current.
i. Mechanical approach:
using a brush. Though it is easy to handle but, I must confess, it leaves rough surfaces on the aluminum workpiece-which is undesirable when it comes to TIG weld of aluminum.
ii. Mechanical approach:
don’t worry, here is another mechanical approach that solves this problem. It is by using a synthetic fleece. Synthetic fleece has particles bound in it with which the oxide layer can be removed far too easily without leaving any roughness in the surface.
This method involves usage of AC supply, where current alternates periodically from positive half cycle and negative half cycle.
Proper control of AC Polarity during the weld is must(discussed in upcoming section). It is because the +ve half cycle breaks up the oxide layer while as -ve half cycle brings about the penetration, i.e, welding depth in the aluminum workpiece.
It must be kept in mind that even after proper cleaning, re-formation of oxide layer is a common occurrence. For this hiccup, Alternating Current serves the process.
There is one disclaimer though: If you intend to weld foils of thick that measure up beyond 10 mm; it is highly recommended then to preheat the workpiece. Doing so will prevent the loss of heat from the welding process to the internal heating of the work piece-which makes the formation of weld seem crude and unnatural.
The selection of the welding torch.
Aluminum can be welded using different processes, namely TIG, MIG and plasma. The TIG welding process with alternating current is mostly used for thinner sheets. Butt joints in particular can be welded well with a
TIG torch. For example, if you want to connect two 2 mm thick sheets of aluminum, you have to make sure that the edge on the back is broken. Only then there will be a nice root, proper wetting of the weld metal and a high quality weld.
How is it done?
In TIG, filler metal is added thus enabling establishment of puddle with proper penetration prior to stuffing it with filler metal.
Optimum amount of heat is to be maintained throughout the process or else you will lose the quality of the welded surface. It is because aluminum is so conductive that it provides a free path to the flow heat thus cooling it at an alarming rate. This property necessitates that a large amount of heat is put in to establish the puddle properly. Plus, excess heat may cause a run away puddle(a kind of leakage)
How is the amount of heat maintained?
Amperage and voltage serve as basic Instruments through which quantity of heat, that is to be given, is determined.
Large Amperage means more heat but is there not a catch in it?? Yes, there is.
Though, Welding with longer Arc produces increased voltage and, as a result, availability of larger amount of heat. But one must not forget that a large amount of heat affects a larger part(extra part) of the workpiece that is to weld. This is a slight disadvantage associated with it. But to escape from this problem short Arcs are recommended to localize the spread of heat in that specific area where welding is to be done.
Adjust the Balance Control
Thanks to the modern technological advancements, instruments have now an advanced balance control set up.
While older instruments were equipped with a 50-50 ratio of EN and EP, modern instruments are provided with a ratio of 75 percent EN to 25 percent.
This increased efficiency in balance control has led to drastic reduction in the problem of “Peppering”, i.e, appearance of small black flecks in the puddle during the welding(undesirable)
Set the AC Output Frequency
This is another factor that ensures the easy weld placement.
It is reminded here that AC output frequency is
different from high-frequency Arc Starting
What is meant by the output frequency is how many times per second the power source switches polarity. This feature is present with better efficiency in modern equipments in comparison to older equipments.
While Older GTA power sources are 60 hertz, which is determined by the input power, the modern equipment is equipped with a factory preset of 120-Hz output frequency.
Use Appropriate Amperage
For every thousandth(0.001) of material thickness, the use of 1 Amp is considered the optimum amperage setting on the equipment.
If this information is translated in percentage: it amounts to 125 amps for welding a material