Details made of aluminum and its alloys are used in almost every branch of industrial production. The use of this light metal with high thermal and electrical conductivity is the most common in household appliances. Therefore, when a malfunction occurs, it becomes necessary to weld aluminum structures and products at home. It is almost impossible to carry out repair operations with this capricious metal without an aluminum welding machine. And if earlier such work was available mainly in industrial conditions, now it is not difficult to perform it in the home workshop.
Features of aluminum welding
The technology of the welding process of aluminum, like any other metal, has its own characteristics. Therefore, a novice welder needs to know and understand many of the characteristics of this metal. There is a wide range of special properties that aluminum has. Welding it involves performing preliminary preparation of the material and direct connection of parts.
In this case, it is necessary to take into account the properties of the metal:
- Always on the aluminum surfacethere is an oxide film, which significantly reduces the welding process. The melting point of the metal is 660℃, while the melting of the film occurs at 2000℃.
- When aluminum welding significantly interfere with the creation of a continuous seam drops of metal, which are instantly covered with an oxide film. It prevents the formation of a high-quality seam in the open air. Therefore, the main condition for welding aluminum is to protect the heating zone with argon.
- Dissolved hydrogen, which is present in the composition of aluminum, is released during welding into the atmosphere, which leads to the formation of crystalline cracks and pores.
- In the molten state, aluminum has a high fluidity, which makes it very difficult to create a weld pool. Therefore, when welding aluminum, it is required to arrange good heat dissipation from the junction.
- Due to the high coefficient of linear expansion of the metal, there is a large shrinkage during cooling.
- High thermal conductivity causes an increase in the amount of current when welding in order to reduce its duration.
- The mode and method of aluminum welding at home is difficult to set correctly due to the difficulty of determining the alloy grade.
Weld quality
To make a strong and reliable connection of aluminum parts, the welder must perform several basic technological steps:
- To remove the oxide film from the surface of the connection of products. This operation can be performed both mechanically by cleaning the junction with a metal brush, and chemically using specialsolvents. But the most effective way would be to weld aluminum with a semi-automatic device in a pulsed mode, which, by means of instant heating of the metal, provides a good removal of the oxide layer.
- Properly heat up the metal surface in the desired temperature range. The main mistake of beginner welders is overheating of the metal, which leads to burning of the joint.
- Significant linear shrinkage of aluminum during cooling can lead to deformation of the weld. Therefore, it is necessary to complete the welding process with a lower current. But at the beginning of work, it is necessary to apply a high current to ensure the penetration of the oxide film.
The quality connection of aluminum products depends on the correct performance of all these operations.
Inverter welding technology
Under certain conditions, welding of aluminum with an inverter is also possible at home. For such work, special attention must be paid to consumables. The requirements for the aluminum welding machine are low. To make a connection you will need:
- Device for heating electrodes. Frying the electrodes is a mandatory and necessary condition for joining aluminum parts. Most often, unsuccessful attempts at aluminum welding occur due to poor preparation of consumables.
- Special electrodes are used for welding metals with high thermal conductivity, which includes aluminum.
- Inverter(aluminum welding machine). Its performance level when used at home does not matter.
The process of connecting aluminum parts must necessarily take place under the protection of an inert gas.
Basic welding steps:
- Preparatory work includes cleaning the surface of the products to be joined and the mandatory preparation of electrodes.
- The welding process must be carried out carefully and slowly, strictly observing the desired depth of penetration. After the end of the welding phase, the gas supply is not turned off for about five seconds.
Electrode properties
The basis of electrodes for aluminum welding is pure metal, the mass of which is predominant, as well as additives that improve the connection process. The mechanical properties of welding fixtures are the main parameter by which they are selected for welding. The strength of the seam depends on this.
Main brands of electrodes for aluminum welding: OZA, OZA-1, OZR-2, OZANA-2. All electrodes are hygroscopic, so they must be dried at a temperature of 200 ℃ before use.
Semi-automatic connection
Welding of aluminum by a semi-automatic device is mandatory under the protection of an inert gas. Argon is used as such a gas. It is possible to conduct aluminum joining by a semi-automatic device without the use of an inert gas, in the case of using consumable flux-cored wire. Such a device inheating time is able to atomize the iron-containing powder. Such a cloud performs the function of protection, like argon.
The disadvantage of this method is the low quality of the weld, which greatly limits its use. The main task of the welder will be to decide which method to make the connection.
TIG technology
This technology uses non-fusible electrodes containing tungsten and an additive wire that automatically fills the seam between parts. The use of such a process involves the use of AC mode and high frequency arc ignition. In this case, the destruction of the oxide film occurs by cathode sputtering at a current with reverse polarity.
MIG method
In MIG technology, the additive is the consumable electrodes themselves for aluminum welding. This material is fed into the connection area by a wire feeder.
Of course, it is very difficult to achieve high quality aluminum welding at home with this method, since you will need to use a device with a pulsed arc mode. When welding, the torch must be directed at an angle of 10-20 degrees to the vertical, while the distance between the joint surface and the nozzle should be up to 10-15 mm.
Aluminum gas welding tips
Before you start welding, you need to prepare all materials and tools. A more reliable connection can be achieved withadditional special rod. After thorough cleaning of the surfaces of the product, these places must be treated with flux. This method of preparation will reduce the influence of the oxide film and will allow semi-automatic welding of aluminum with the highest quality.
Next, the gas burner turns on and heats up to the optimum temperature. The next step is to heat the welded joint to the melting temperature of the metal. During such heating, an additional rod is applied to the junction. During these operations, metals are melted and mixed, resulting in a welded joint.
Remember that joining aluminum at home for a novice welder is considered a difficult job. Such problems mainly depend on the characteristics of the material used. A beginner will have to be patient to gain the necessary experience in welding aluminum surfaces.
