How do you weld aluminium?
Since the flow behaviour of aluminium differs significantly from that of other metals due to its higher thermal conductivity, welding requires experience and maximum precision. Special tools are required to weld aluminium professionally and durably.
Tools for aluminium welding
A TIG (Tungsten Inert Gas) or TIG (Tungsten Inert Gas) welding device is advantageous, because almost no sharpeners are produced during welding, the health risk is lower and particularly high-quality welds are produced. The noble gas argon or helium is used for shielding. Helium is more expensive, but has a better thermal conductivity. For high stability a mixture of argon and helium is usually used.
The shielding gas is led to the welding point through a gas nozzle. For manual welding a filler material can be used, the aluminium welding rod, which connects the parts to be welded. Dirty or rusty welding rods lead to a weak connection, therefore highest cleanliness should be ensured. Depending on the application, TIG welding can also be carried out without filler material.
Safety when welding aluminium
Since welding is carried out at extremely high temperatures and spattering or flying sparks can occur, special protective equipment is essential. A special welding helmet with a viewing window and automatic darkening is required, as the ultraviolet radiation damages the eyes and skin. You also need thick, well-insulated and fireproof gloves. The outer clothing should also be thick and flame resistant, such as cotton and cover the arms because of the ultraviolet radiation.
Preparation for aluminium welding
Aluminium and welding rod must be cleaned before welding. A thin layer of aluminium oxide quickly forms on the aluminium, which melts during welding and makes the weld porous and unstable. The aluminium oxide layer can be brushed off with acetone, water and soap and a stainless steel brush. The joints are sprayed with acetone, the workpiece is washed with water, dried thoroughly and later scrubbed with a stainless steel brush.
The welding rod must also be cleaned with sandpaper so that the seam holds securely. As aluminium is easier to work with when heated, it should be heated to 180°, especially if the workpiece is thicker. In order to guarantee a complete and stable fit, the parts must be filed beforehand, otherwise holes could form in the joint seam due to the oxygen. In order not to slip, the two workpieces are clamped firmly together.
The welding of aluminium
Depending on how thick the parts to be welded are, the voltage of the TIG welding machine must be adjusted. Usually 1 ampere per 0.0025 mm thickness is used. It is also possible to adjust the voltage downwards afterwards. The tungsten or tungsten electrode is placed on the workpiece, whereby only a small current flows.
When the electrode is withdrawn, the plasma arc ignites and the current increases to the required welding current. Now the workpiece is melted until a uniform melt pool is formed. With the welding rod, so much material is added until the joint is filled.
Tool and material list for the welding of aluminium
- Welding equipmentAluminium welding rodArgon gas/heliumWelding helmetInsulated glovesFire extinguisherLongsleeve fireproof clothingAcetoneWaterStainless steel brushClampsFileSanding paper