Judging by the reviews, many home craftsmen are faced with the need to connect aluminum tubes. In most cases, this task is accomplished by rolling - a simple, affordable and safe method for equipment. Nevertheless, sometimes it is necessary to solder aluminum tubes. If you have basic technical knowledge, then you can cope with this task yourself. About how to solder an aluminum tube at home, you will learn from this article.
What is the feature of work?
According to experts, air conditioners are not equipped with spare pipes. Therefore, you will have to go after them to a hardware store.
You can also get a copper tube in which there are impurities of silver. The main thing is that the product is not subject to corrosion, withstands significant pressure and temperature drops without deformation. How to solder an aluminum tube? Two methods can be used, namely high and low temperature. In the first case, a temperature of at least 600 degrees is needed to melt the solder. Also, this indicator can reach 900. The method is designed to work with pipes that can withstand heavy loads. Low temperature is used for pipes with less load in refrigeration units. If you have to work with soft solder, then the temperature indicator reaches 450 degrees, and more with hard solder.
About materials and equipment
Before you weld an aluminum tube, get the following tools:
- Pipe cutter. It is necessary to prepare the end of the tube, which will be connected by solder.
- Pipe bender. If you work without this tool, then, most likely, creases will form on the tube, which will negatively affect the patency. With the help of a pipe bender, you can bend the pipes at the desired angle.
- Soldering iron and gas burner.
- Solder. It can be hard or soft. Sealed and durable soldering directly depends on the surface cleanliness.
Of course, you have to purchase the handset itself. Its diameter depends on the power of the equipment. The more powerful it is, therefore, the larger will be the diameter. The price of the product will depend on its technical characteristics, properties of the metal and brand of the manufacturer. According to experts, it is not worth saving on aluminum tubes, since this will affect the quality of the device and its operational life.
About solders
For those who do not know how to solder the aluminum tube of the air conditioner, we can recommend the use of copper-phosphorus and silver solders. For a phosphoric copper product, it is better to replace the solder in which there are silver ions. The fact is that the phosphorus substance is quite brittle in alloys in which the amount of nickel exceeds 10%. If cadmium is contained in the solder, then you will have to worry about your health because cadmium vapor can poison your body. Before you seal the aluminum tube in the refrigerator, you should determine the type of connection. For example, copper with copper, with steel and with aluminum.
In the first case, you will have to work with copper solder. The joint with the burner needs to be heated to 600 degrees (it will become a dark cherry color). Next, the solder should be dipped into the flux. For melting to occur, you need to press the bar to the heated joint. With joints, steel-steel and copper-steel work with silver-containing solder, which is also called silver. Melting a solder with a high silver content will require a lower temperature. In addition, it has better wettability and streamlining, unlike copper-phosphoric ones, which require a higher temperature to melt.
Flux
Due to the specific chemical structure of aluminum during soldering, you may have difficulty. The reason is that aluminum is a fairly active metal.
This means that reagents can be various chemicals. During the interaction of this non-ferrous metal with oxygen, the formation of a very thin and at the same time unusually strong oxide film is observed on the surface of the product. Due to the fact that the properties of aluminum and its oxide are completely opposite, the formation of this film should be completely excluded. For this purpose, you will need a flux.
Using this auxiliary material, oxides are removed from the solder and the surface of the soldered product. In addition, flux prevents their formation. Judging by the reviews, the best brand is F-64 with 40% active fluorine content. After work, the soldered surface must be washed. Gumboil A-214 is considered a universal non-laundering agent with a melting point from 150 to 400 degrees. After work, its residues are easily removed with a regular cloth, which is pre-moistened with alcohol.
What is the essence of the procedure?
Before you weld an aluminum tube, you should understand what constitutes a soldering process. The formation of compounds by soldering occurs in two stages. First, physical contact is created between the surfaces. Next, the physical contact is transformed into a quantum-mechanical interaction between the electron shells of atoms. To initiate physical contact between surfaces and further chemical bonding, the brazed metal is wetted with liquid solder. The appropriateness of its use depends on such an indicator as the type of interatomic forces on the contacting surfaces. If physical adsorption is observed, as a result of wetting with liquid solder, a low-strength compound will be obtained. If liquid and solid metals chemically interact, a strong bond is formed by wetting.
Surface heating
For those who do not know how to solder an aluminum tube and where to start, experts recommend pre-preparing the surfaces of the parts to be joined. They are heated with a sheaf of flame. It is desirable that it is at a distance of 1 cm from the surface. If you need to connect massive parts, it is better to use multi-nozzle burners with soft and uniform heating. Copper-zinc solders are melted using an oxidizing flame, in which the evaporation of zinc is reduced.
Stainless steels are heated with a normal flame. The main thing is that at the same time chromium carbides do not form, capable of initiating intergranular corrosion. If it is necessary to solder dissimilar parts having different thicknesses, then the flame must be directed to a surface with greater thermal conductivity and mass.
About flame soldering
In this case, you will need a special burner that runs on domestic gas, propane or acetylene. It is used to heat parts whose thickness does not exceed 1 cm. In addition to aluminum, acetylene burners are used for heating and brazing carbon and low alloy steels, gray cast iron, copper, nickel, copper-nickel alloys, silver and gold. It is necessary to determine the temperature at which the soldering will be carried out. It is important that this indicator is 50 degrees higher than the melting point of the solder used. For flame brazing, tin-lead, tin-zinc, copper, silver, aluminum and gold solders are suitable. The procedure lasts for three minutes. Propane is supplied under pressure up to 400 kPa (not lower than 100), acetylene from 60 to 80, household gas - 30 kPa. When choosing a flux, you will have to come from the temperature and solder properties. Gaseous fluxes can also be used.
About repair of automobile conditioners. Ways
Often car owners ask a question, how to solder an aluminum tube of a car air conditioner? Some are trying to fix the problem on their own. If this task is performed incorrectly, then you will have to go to the service station so that the specialist redo everything. There are two ways to restore aluminum tubes, namely by brewing a crack or by spraying a special composite substance on them.
Causes of breakdowns
It may be that the aluminum tubes in the car’s air conditioner are just clogged. This happens mainly in the winter, when the air conditioner does not work. As pollutants accumulate between the radiators in the air conditioner and the engine, the entire line becomes clogged. As a result, the refrigerant will circulate and mix with moisture no longer fully. Due to the presence of reagents, violation of moisture levels and temperature changes, aluminum is destroyed, of which the tubes are made. Thus, their operational resource depends on the climate, temperature conditions, features of the road surface, participation in road accidents and general loads on the car. Together, these factors will negatively affect the state of the cooling system.
Where to begin?
First of all, you need to diagnose the device. According to experts, it will be difficult to do this by eye. The fact is that the tube can be with microcracks, through which freon flows. Since the refrigerant is colorless, its leak is detected using special equipment. They begin with an external inspection, then measure the pressure of the refrigerant, and then using the ultraviolet diagnostics and a leak detector, determine the place of leakage of freon. If you do not want to waste your time troubleshooting, immediately use the services of specialists. For example, in the south-east of Moscow you can solder an aluminum tube in several car service centers. For example, in the Red Hot Service, in addition to soldering the pipes of the cooling device, you will also perform other work, namely, change the oil, fill the air conditioner, and repair the electrical equipment.
Repair small cracks
For those who do not know how to solder an aluminum tube, experienced craftsmen will recommend the use of special compounds. If the tubes in your air conditioner have very small cracks that are barely visible to the eye, then you can do without argon-arc welding. Special patches are applied to the holes in the tubes. It is important that their thickness is at least 3 mm. For this, aluminum tubes with a mixture should be coated in several layers. If the cracks are large, then you can not do without argon-arc welding. Its advantage is that it excludes contact of the surface with oxygen, and, consequently, the formation of oxides. Thus, working with argon-arc welding, you can do without flux.
Progress
Judging by the numerous consumer reviews, everyone can cope with this work, even with little soldering experience. To get started, get a pipe cutter, a special bending machine and welding. Some home craftsmen use a hacksaw instead of a pipe saw. According to experts, this is not worth doing, because the quality of work will not be that. The pipe bender can be universal (they work with different diameters) and specific (designed for tubes of a certain diameter).
Next, you should buy aluminum tubes, cut the desired length from them and bend on a bending machine. After making the tubes, cut into the fittings and connect everything into one system. Before connecting, thoroughly clean the tubes with sandpaper or a metal brush. If grease, paint or earth remains on the products, the adhesion of the metal to the solder will be worse. If you want to connect two tubes, insert them into each other so that a small gap (0.2 cm) remains, which will be further filled with molten solder. After performing these steps, you can proceed directly to the soldering itself.