Complete Guide to TIG Welding on Aluminium

TIG (Tungsten Inert Gas) welding on aluminium is a widely used welding technique in the carpentry sector and in the production of components for industry, mechanics and design. Its popularity is due to its high quality performance in terms of strength and durability, as well as the high aesthetics of the manufactured joints. In this comprehensive guide we will find out everything about TIG welding on aluminium.

Introduction to the TIG process

TIG welding, also known as GTAW (Gas Tungsten Arc Welding), is a type of arc welding that uses an infusible tungsten electrode and an inert gas to protect the arc and weld pool. Due to the use of the inert gas, usually argon or helium, the process significantly reduces the risk of contamination from oxygen and other atmospheric gases, thus improving the quality of the welds made.

Characteristics of TIG welding on aluminium

The main features of TIG welding on aluminium are:

•  High quality of joints between materials;
•  Drastically reduced risk of porosity formation;
•  High corrosion resistance of welded joints;
•  Excellent durability and fatigue life of assembled materials;
•  Excellent aesthetics of machined surfaces.

Preparazione del materiale

Before starting TIG welding on aluminium, it is important to properly prepare the materials to be welded. Cleaning the surface of the material is essential to ensure that the inert gas protects the arc and the weld pool effectively.

Cleaning the surfaces to be welded

To achieve good quality welded joints, it is necessary to remove any impurities on the surface of the aluminium, such as oxidation, grease or oil. It is recommended to use specific aluminium cleaners and non-aggressive stainless steel or plastic bristle brushes to avoid scratches or damage to the aluminium surface. Once the surfaces have been cleaned, the parts to be welded are assembled.

Choosing the correct electrode and filler

Il tipo di elettrodo e il materiale di apporto scelti possono influire significativamente sulla qualità e sull’estetica della saldatura TIG su alluminio.

Electrode type

For TIG welding on aluminium, it is advisable to use pure tungsten electrodes, as they offer greater arc stability and better performance. The electrode should be sharpened to a point between 30-60 degrees to facilitate arc initiation.

Scelta del filler

The filler material must be chosen according to the type of aluminium being welded and the specific application required. Some of the most common filler materials for TIG welding on aluminium are:

•  4043: This filler material offers high corrosion resistance and is often used to weld aluminium-silicon alloys;
•  5356: Provides good strength and ductility and is suitable for welding Al-Mg alloys;
•  5183: Provides a good combination of strength and ductility and is mainly used in the welding of marine structures and vessels.

Current settings for welding aluminium

Aluminium has a very high thermal conductivity, which means that it heats up quickly during welding. For this reason, it is important to set the welding current correctly to achieve good penetration and a controlled melt pool.

Setting the current type

Aluminium requires alternating current (AC) during TIG welding. The AC current allows the surface oxide to be broken, facilitating the welding process.

Current amplitude adjustment

The amplitude of the current must be selected according to the thickness of the material being welded. A general rule of thumb is to use approximately 1 ampere per 0.025 mm thickness of the aluminium being welded, for example:

•   Thickness 1 mm: current of 40 A;
•  Thickness 3 mm: 120 A current;
•  Thickess 5 mm thick: current of 200 A.

Setting the frequency

The frequency of the AC current affects arc stability and the characteristic of TIG welding on aluminium. Higher frequencies offer greater arc stability and better penetration into the tungsten, while lower frequencies offer greater cleanliness but less penetration. A frequency between 80 and 180 Hz is usually indicated for TIG welding on aluminium.

TIG welding techniques for aluminium

Once the machine to be welded has been correctly configured, TIG welding can be performed on aluminium. Welding techniques vary depending on the type of joint and welding positions.

Welding positions

The most common welding positions for TIG welding on aluminium are:

•  Horizontal plane: This is the easiest welding position, as the workpiece is positioned horizontally;
•  Vertical plane: In this position, the workpiece is positioned vertically and welding is performed from top to bottom;
•  Inclined plane: The workpiece is positioned inclined and welding is performed so that the weld pool follows the slope of the workpiece.

Developing skills in TIG welding on aluminium requires time, patience and practice. This comprehensive guide provides an overview of all the information needed to successfully start working on this type of material.