Can TIG welding work with alternating current

Welding aluminum: explanation, instructions and tips

Welding aluminum takes experience and a steady hand to get good results. Here we explain to you which equipment you need and how to properly approach the demanding work.

Welding aluminum: explanation, instructions and tips
Welding aluminum: explanation, instructions and tips

A special feature of welding aluminum is the high thermal conductivity of the metal. This exceeds that of other metals by far. Due to the increased conductivity, the heat expands quickly and great stresses can arise within the workpiece. An uncontrolled delay occurs when unsuitable welding processes are used and incorrect equipment is used.

Aluminum does not discolour during welding and therefore does not optically indicate when the melting point has been reached. A welding task with aluminum can therefore only be safely mastered with welding experience.

Tip: If you have little experience so far, we recommend attending a welding course beforehand in order to acquire the basics. If you want to teach yourself the welding process, it makes sense that you first practice it on a few pieces of aluminum scrap and examine the result critically before you tackle the actual welding task.

TIG and TIG: welding processes for welding aluminum

Tungsten inert gas (TIG) or tungsten inert gas (TIG) welders are best for welding aluminum. Tungsten is the English word for tungsten, so TIG and TIG are one and the same welding process. In the following, we will only speak of TIG welding because that is the German abbreviation.

When welding aluminum with TIG welding machines, it is important that ...

  • very few splashes develop
  • the health burden is low
  • the weld seams are of stable and high quality

Work safety tip:In order to protect the respiratory tract and the entire body from gases, vapors, smoke and dust, you should always wear a suitable protective mask, even when cleaning. Also ensure that the workplace is adequately ventilated.

Equipment and tools for welding aluminum

Before you start welding aluminum, you should have the tools and materials you need. The most important thing is to choose a suitable welding machine. We introduce you to two tried and tested welding machines:

Berlan TIG / TIG inverter

Robust, versatile and handy - the Berlan welding machine has these properties. The protective gas is missing in the basic equipment, but it can be bought for relatively little money. The price-performance ratio is good, and the welding machine does very well in the test.

Rating: 4.4 out of 5 stars

TIG welding inverter WE 200 P from WELDINGER (promotion set)

An all-rounder for professionals and experienced do-it-yourselfers: the TIG welding inverter from WELDINGER welds steel, stainless steel, copper and aluminum - and that with acceptable power consumption. The extensive accessories include adapter sleeves and tungsten needles. The slightly higher investment is worthwhile due to the wide range of possible uses.

Rating: 4.8 out of 5 stars

Materials and accessories for welding aluminum

The following table shows other accessories that are essential for aluminum welding.





Aluminum welding wire

TIG welding wire

5 of 5

around 15

Welding helmet

FIXKIT solar welding helmet

4.4 out of 5

about 30

Fireproof gloves

Welding gloves

4.7 out of 5

around 16

Fire extinguisher

Smartwares powder extinguisher
with bracket

4.5 out of 5

around 16

Fireproof outerwear

Queen welding apron
made of buffalo leather

4.2 out of 5

about 40

Abrasive material such as stainless steel brush,
Grinder, sandpaper
and file

S&R wire brush set for
drilling machine

4.6 out of 5

about 10

In addition to the materials mentioned, you need water and acetone for cleaning, screw clamps to fix the workpiece and shielding gas for the work process. You can easily purchase the latter from specialist retailers on site; the exchange is based on a deposit for an empty bottle.

Guide: How does TIG welding work?

With TIG welding, the welding point is shielded by noble gas - it prevents chemical reactions of the aluminum with atmospheric oxygen and other gases. Argon or helium can be used as protective gas. Although helium is more expensive, it has a higher thermal conductivity. A mixture of argon and helium is ideal. The shielding gas is fed directly to the welding point via a nozzle. With the help of an aluminum welding rod, the parts can be neatly connected. It is important that you work precisely and cleanly, because dirt or rust on the welds cause unstable connections. Before going into the step-by-step instructions, the following graphic should show how TIG welding with alternating current (= AC) works in principle.

TIG welding: step by step instructions

Put on protective clothing and maintain an environment free of flammable materials. Since you work with gas, you need a workplace that is sheltered from the wind. TIG welding outdoors is not advisable because a gust of wind could unexpectedly tear open the protective gas envelope. The result would be an unclean seam that is prone to breakage.

  • First of all, the surfaces of the areas to be welded must be cleaned thoroughly. They must be free of corrosion, grease, dirt, paint and other residues. Correct cleaning is as follows: First, remove oil, grease and other impurities with acetone. Then use the wire brush to loosen the surface corrosion layer of aluminum oxide - it is very thin and easy to recognize by its lighter color. Wash the work pieces with water and dry them carefully.
  • If necessary, the surfaces should be processed with grinding equipment. Above all, sharp, so-called root edges must be removed from the joints between the two workpieces to be connected. You can easily round off the sharp-edged corners and burrs after cutting the material with a belt sander. If this does not happen, there is a risk that the weld seam on the underside will tear and become unstable.
  • If necessary, sharpen the tungsten electrode lengthways.
  • Connect the ground cable from the welder to a bare point on the aluminum.
  • Use a welding rod that matches the workpiece thickness. The welding rods must also be free of oil, grease, scale and other contaminants.
  • Set the starting voltage and delay on the welding machine.
  • Set the amount of gas. This depends on parameters such as electrode diameter and workpiece thickness. In a welding course you will learn how to calculate the correct amount.
  • Activate the shielding gas supply.
  • Ignite the arc and bring the tungsten electrode within 2 millimeters of the aluminum to be welded.
  • You can now start welding. Make sure that the electrode axis is inclined at an angle between 5 and 20 degrees to the weld bead (= weld seam) and that the arc length is between 3 and 5 millimeters, depending on the welding task. If you do not start welding immediately, but a few days later, cover the cleaned pieces of metal with packing paper to prevent them from gathering dust or, if necessary, clean them again shortly before welding.