Judging by the reviews, many home craftsmen are faced with the need to connect aluminum tubes. In most cases, this task is performed by rolling - a simple, affordable and equipment-safe method. However, sometimes aluminum tubes need to be soldered. If you have basic technical knowledge, then you can cope with this task yourself. You will learn how to solder an aluminum tube at home in this article.
What is special about the job?
According to experts, air conditioners are not equipped with spare pipes. So you have to follow them tohardware store.
You can also get a copper tube that contains silver impurities. The main thing is that the product is not subject to corrosion, can withstand significant pressure and temperature changes 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 tubes that can withstand heavy loads. Low temperature is used for less stressed pipes in refrigeration applications. 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 soldering the aluminum tube, get the following tools:
- Pipe cutter. It is necessary to prepare the end of the tube, which will be connected with solder.
- Pipe bender. If you work without this tool, then, most likely, creases form on the tube, which will adversely affect the patency. With a pipe bender, you can bend pipes to the desired angle.
- Soldering iron and gas burner.
- Solder. It can be hard or soft. Tight and strong soldering directly depends on the cleanliness of the surface.
Of course, will have to purchasethe handset itself. Its diameter depends on the power of the equipment. The more powerful it is, therefore, the larger the diameter will be. The price of the product will depend on its technical characteristics, the properties of the metal and the brand of the manufacturer. According to experts, it is not worth saving on aluminum tubes, as this will affect the quality of the device and its service life.
About solders
Those who do not know how to solder an aluminum tube of an air conditioner can be recommended to use copper-phosphorus and silver solders. For copper products, it is better to replace phosphorus solder with silver ions. The fact is that the phosphorus substance is rather brittle in alloys in which the amount of nickel exceeds 10%. If your hard solder contains cadmium, then you have to worry about your he alth, because cadmium vapor can poison your body. Before soldering an aluminum tube in a refrigerator, the type of connection should be determined. 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 a burner must be heated to 600 degrees (it will turn dark cherry). Next, the solder should be dipped into the flux. For melting to occur, you need to press the bar to the heated joint. With steel-steel and copper-steel joints, they work with silver-containing solder, which is also called silver. Solder with a high silver content will require a lower temperature to melt. In addition, hehas better wettability and flowability, unlike copper-phosphorus, which require a higher temperature to melt.
Flux
Due to the specific chemical structure of aluminum, you may experience difficulties during soldering. The reason is that aluminum is a fairly active metal.
This means that various chemicals can be used as reagents. When this non-ferrous metal interacts with oxygen, the formation of a very thin and at the same time extremely 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.
With the help of this auxiliary material, oxides are removed from the solder and the surface of the soldered product. In addition, the flux prevents their formation. Judging by the reviews, the best brand is F-64 with 40% active fluorine content. After work, the surface to be soldered must be washed. Flux A-214 is considered a universal non-cleaning agent with a melting point of 150 to 400 degrees. After work, its residues are easily removed with a regular cloth, which is pre-moistened with alcohol.
Whatessence of the procedure?
Before you solder an aluminum tube, you should understand what the process of soldering is. The formation of connections by soldering occurs in two stages. First, physical contact is made between the surfaces. Further, the physical contact is transformed into a quantum mechanical interaction between the electron shells of atoms. To initiate physical contact between the surfaces and further chemical bonding, the metal to be brazed is wetted with liquid solder. The expediency of its application depends on such an indicator as the type of interatomic forces on the contacting surfaces. If physical adsorption is observed, then as a result of wetting with liquid solder, a low-strength joint will be obtained. If liquid and solid metals interact chemically, then 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 be at a distance of 1 cm from the surface. If you need to connect massive parts, then it is better to use multi-nozzle burners with soft and uniform heating. Copper-zinc solders are melted using an oxidizing flame, which reduces zinc evaporation.
Stainless steels are heated with a normal flame. The main thing is that chromium carbides, which can initiateintergranular corrosion. If you need to solder dissimilar parts with different thicknesses, then the flame must be directed to a surface with greater thermal conductivity and mass.
About flame brazing
In this case, you will need a special burner that runs on household gas, propane or acetylene. It is used to heat parts whose thickness does not exceed 1 cm. In addition to aluminum, acetylene torches are used for heating and soldering 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 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 soldering, 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 proceed from the temperature indicators and the properties of the solder. You can also use gaseous fluxes.
About the repair of car air conditioners. Ways
Often, car owners ask how to solder the aluminum tube of the car air conditioner? Some try to fix the problem on their own. If this task is not performed correctly, then you will have to go to the service station so that the specialistremade. There are two ways to restore aluminum tubes, namely by welding 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 winter, when the air conditioner is not working. As contaminants accumulate between the radiators in the air conditioner and the engine, the entire line becomes clogged. As a result, the refrigerant will not circulate and mix with moisture to the full extent. Due to the presence of reagents, violation of the moisture level and temperature changes, the aluminum from which the tubes are made is destroyed. Thus, their operational life depends on the climate, temperature conditions, road surface characteristics, participation in traffic accidents and general loads on the car. Together, these factors will adversely affect the state of the cooling system.
Where to start?
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 out. Since the refrigerant is colorless, its leakage is detected using special equipment. They start with an external inspection, then measure the pressure of the refrigerant, and then with the help of ultraviolet diagnostics and a leak detectordetermine the location of the freon leak. If you do not want to waste your time troubleshooting, immediately use the services of specialists. For example, in the southeast of Moscow, you can solder an aluminum tube in several car services. For example, in Red Hot Service, in addition to soldering the pipes of the cooling device, they will also perform other work for you, namely, they will change the oil, fill the air conditioner, and repair electrical equipment.
Fixing small cracks
For those who do not know how to solder an aluminum tube, experienced craftsmen will recommend using special compounds. If the pipes in your air conditioner have very small cracks, 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. To do this, aluminum tubes should be coated with a mixture in several layers. If the cracks are large, then you can not do without argon-arc welding. Its advantage is that it excludes the contact of the surface with oxygen, and, consequently, the formation of oxides. Thus, when working with argon-arc welding, you can do without flux.
Progress of work
According to the numerous customer reviews, anyone with little soldering experience can handle this job. To get started, purchase a pipe cutter, a special bending machine and welding. Some home craftsmen use a hacksaw instead of a pipe cutter. According to experts, this is not worth doing,because the quality of the work will not be the same. A pipe bender can be universal (they work with different diameters) and specific (designed for pipes of a certain diameter).
Next, you should buy aluminum tubes, cut them to the desired length and bend them on a bending machine. After preparing the tubes, cut the fittings and connect everything into one system. Before connecting, clean the tubes thoroughly with sandpaper or a wire brush. If grease, paint or earth remains on the products, then 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 there is a small gap (0.2 cm) that will later be filled with molten solder. After completing these steps, you can proceed directly to the soldering itself.
