The opinion that it is very difficult to solder elements made of aluminum or alloys based on it is largely erroneous. Of course, if you use compositions designed to work with copper, brass or steel for this, then it is almost impossible to get a positive result. Special solders for soldering aluminum will greatly simplify this process.
Features of aluminum and alloys based on it
Difficulties that arise when soldering aluminum are due to its specific features:
- high resistance oxide film on the surface;
- low melting point;
- high heat capacity.
According to the temperature indicators at which aluminum is soldered, there are two main methods:
- low temperature in the range of 150-300⁰С (soft soldering);
- high temperature - 390-580⁰С (hard soldering).
Given the characteristics of the metal, manufacturers have developed special solders and fluxes for soldering aluminum.
Benefits of soldering
Previously, special argon welding was used to connect aluminum parts. Such work required an expensiveequipment, and only a highly qualified specialist could use it. In addition, in the place of welding, the metal was destroyed in depth.
Soldering aluminum with solders and fluxes is devoid of all the above disadvantages and has a number of advantages:
- Available fixtures are used to fasten parts.
- Works can be done even by an unskilled performer, that is, they can be done independently at home.
- The integrity and structure of the connected parts are not violated.
- With proper soldering technology, the mechanical strength of the joint is not inferior to welds.
- Reheating makes it easy to change the relative position of the parts and the soldering point.
High temperature aluminum brazing
In order to firmly connect sufficiently large aluminum elements, so-called hard soldering is used. For this you will need:
- gas burner;
- metal brush;
- solder.
The algorithm for the production of work is quite simple:
In the places of soldering, carefully clean the parts using a steel brush
We heat the junction of the parts with a gas burner to the melting temperature of the solder (for modern compositions this is usually 390-400⁰С)
- Tightly press the solder bar to the soldering point and apply it to the surface with reciprocating movements.
- Steel brush remove the oxide film under the molten solder.
- Let the parts cool naturally.
Solders for hard soldering
For a long time, only 34A solder was available to Russian consumers. The main component of this composition is aluminum (up to 66%). The soldering temperature is 530-550⁰С. It is necessary to work with it with extreme caution so as not to melt or damage the fastened parts, because the melting of aluminum itself begins already at 660 ° C. In addition, when performing work, on the recommendation of the manufacturer, the solder rod must be periodically dipped in F-34A flux.
The temperature of aluminum soldering with HTS-2000 (American-made) is about 400 degrees. The elements are connected without the use of flux. This greatly simplifies the process.
Another fairly popular and common flux-cored solder is Swiss Castolin 192 FBK. Its soldering temperature is slightly higher - 440 degrees. The presence of flux in the structure of the rod facilitates the removal of the oxide film from the surface and ensures reliable adhesion of the solder to aluminum.
Both of the above imported compositions are made on the basis of zinc, so the soldering point has high anti-corrosion properties.
Recently foreignmanufacturers, a worthy competitor appeared - Super A + solder for aluminum soldering, which was developed and is now manufactured in Novosibirsk. According to its technical characteristics, it is in no way inferior to Western counterparts. The process of hard soldering is carried out at the same 400 degrees acceptable for metal. And there is no need to use flux. But the price for it is much lower (2-3 times) than that of its Western counterparts. The developers prudently do not publish the composition of the ingredients yet.
Low temperature aluminum brazing
Since soft soldering is usually carried out at a temperature in the range of 230-300 ⁰С, you will need for it:
- electric soldering iron;
- solder for aluminum brazing;
- flux;
- handy tools for cleaning parts (steel brush, file or sandpaper).
Work order:
- Clean the parts to be joined by any mechanical means.
- Fix them in the right position.
- Apply flux to the place of soldering (for example, with a brush).
- The tip of the (preheated) soldering iron and the solder bar rest against the junction.
- The solder starts to melt. Advancing the soldering iron, we solder the entire seam of the joint.
- Let the fastened parts cool.
- Carefully clean the place of soldering from flux residues (for example, with a cloth or rag soaked in alcohol).
Solders for aluminum soft soldering
Aluminum brazing is currently usedformulations from various manufacturers. Many successfully solder aluminum with Russian-made P250a solder. It is made on the basis of tin (80%). It also contains zinc (19.85%) and minor additions of copper (0.15%). The low price and availability of the acquisition provided him with sufficient popularity.
Quite common in our country is the Swiss Castolin 1827 solder for aluminum soldering. It contains silver, cadmium and zinc. However, the price for it is much higher than the Russian counterpart. In addition, manufacturers strongly recommend using it only with fluxes of their own production.
Fluxes for aluminum brazing
Fluxes dissolve and remove the oxide film from the metal surface, and also contribute to better spreading of the molten solder, which ultimately affects the quality and strength of the connection. Therefore, they must be chosen as carefully as aluminum solder.
Russian manufacturers ("SmolTechnoKhim", "Connector", Rexant, "Zubr") offer two main types of liquid active fluxes: F-59A and F-61A. The letter index "A" in the marking means that their composition is designed specifically for soldering aluminum, alloys based on it, as well as combined compounds with copper, steel and other metals.
Among the imported liquid fluxes for soft soldering, the Russian user is best known for the Swiss Castolin AluTin 51. The carefully designed and well-balanced composition is suitable for bothfor soldering aluminum elements, and in combination with other metals.
All of the fluxes listed above are designed for low temperature soldering (in the range from 150 to 300 degrees). Brazing aluminum is carried out mainly either without the use of fluxes, or its components are built into the structure of the solder rod.
In conclusion
From all of the above, we can draw an unambiguous conclusion: the process of soldering aluminum elements is quite simple and accessible to everyone. Knowing what supplies to buy and what tools to use, you can either solder aluminum electrical wires together or repair a cracked automatic transmission oil pan.
