Before soldering copper, you need to take into account that it belongs to metals that can be easily soldered. This is due to the fact that the surface of copper can be easily cleaned without resorting to aggressive substances. Copper is a weakly corrosive metal. Many low-melting alloys and metals, for example, brass, have good adhesion with copper. When copper is heated in air during brazing, complex oxygen fluxes do not react with oxygen and are not required for brazing.
Scheme of argon arc welding of copper.
For example, copper water pipes have much more flexibility than steel pipes, they are durable and resistant to chemical elements, but have a higher cost. Plumbing and heating systems made of copper have the same service life as the entire structure, and can be bricked up or covered with concrete, and covered with various wall panels. The requirement for a monolithic placement of copper communication pipes is the use of gasket materials such as corrugation or PVC-based insulation. They will prevent mechanical effects of various types when changing the climate regime in winter and summer.
Tools and materials for copper soldering
- pipe cutter;
- pipe expander;
- metallic wool;
- soldering iron;
- soldering oil;
Scheme of the electric welding apparatus.
A pipe cutter is required to cut the pipe lengthwise. The principle of operation of pipe cutters is the same, although there are a lot of models on sale. The pipe for its trimming is clamped between the rollers and the blade, then the pipe cutter is rotated around, tightening the bottom bolt for a third turn. To get a smooth edge, the pipe is kept strictly perpendicular to the tool. The pipe is usually cut in 5-6 turns. It is possible to make low-temperature brazing of copper with a gas torch, since its temperature does not exceed 450 °. Not all burner designs available on the market are suitable for soldering.
Before you choose a burner in order to solder the copper, you need to pay attention to the instructions, as those burners, the use of which begins with the ignition of the brazier, are not suitable for these purposes. How to solder copper? You need to do this with a soldering iron or a torch with a narrow flame. Such a burner will heat the pipe in a matter of seconds, and the gas cartridge will be enough for economical use for a long time. When choosing a burner you need to look at the composition of the gas in the cylinder. As a rule, it is a mixture of propane and butane, but the higher the butane content, the higher the flame temperature.
Metallic wool is used to clean the copper before working with a torch and a soldering iron. She tightly compresses the end of the pipe or wire and perform with the force of several rotational movements. For the wire it is enough, and the pipe should be cleaned also from the inside. Narrow pipes (fittings) can be cleaned with special brushes designed for this purpose, while the use of sandpaper, especially large fractions, and especially a file, is strictly prohibited. Copper is a soft metal, and when using emery paper, emery components will remain on the surface, preventing adhesion and good bonding.
The scheme of spot welding of copper.
Solder can be purchased coiled for ease of use in coils. This is tin wire, which diameter is about 3 mm. It is advisable to pay attention to the absence of lead in the solder, which should be indicated by a special inscription on the coil. An important component for soldering is the flux, which wets the base metal (in this case, copper) before soldering, penetrating into all capillaries. Flux spreads over the surface under the action of capillary forces. Before you properly solder, the surface must be completely clean and free from oxides. The seam will be strong only if the components are protected from oxygen present in the air. The use of flux increases the adhesion of the solder on a par with mechanical cleaning of surfaces.
When using flux it does not play a big role, whether it is intended for solder with or without lead, these varieties are interchangeable. Fluxes for brazing stainless steel are unsuitable for use with copper. Ordinary rosin can also be used, but problems with its application are possible.Back to table of contents
Copper Soldering Rules
When it is necessary to solder a copper product or a product containing copper components, it is impossible to give an unequivocal answer how and how best to do it. The choice of method and tools depends on many factors, such as the size and weight of parts, their composition. The load to which the already welded products must be subjected is also taken into account. There are several ways of soldering, and it is better to know them all in order to choose the most suitable one, if necessary.Back to table of contents
Soldering large parts
Scheme of capillary soldering of copper.
If you need to solder massive or large parts that can not be heated to the desired temperature using a soldering iron, use a torch and copper solder. The flux in this case is the borax. The strength of copper-phosphorus solder is higher than that of standard tin.
A thin layer of flux is applied to the mechanically cleaned pipe or wire. After that a fitting is put on the pipe, also mechanically cleaned. With the help of a gas burner, the joint is heated until the copper coated with the flux changes color. The flux should be silver, after which you can make a solder. The solder melts instantly and penetrates the gap between the pipe and the fitting. When the solder drops begin to remain on the surface of the pipes, the solder is removed.
Do not overheat the pipes, as this does not contribute to the appearance of a larger capillary effect. On the contrary, copper, heated to blackness, is less amenable to soldering. If the metal began to turn black, the heating should stop.Back to table of contents
Solder wire or wire
To solder thin copper wires, you should not use a zinc chloride based solder, as it will destroy the copper. If there is no flux available, you can then dissolve an aspirin tablet in 10-20 ml of water.
The scheme of welding copper in inert gases.
Copper wire or wire parts of different cross sections can be easily heated for the desired temperature using a soldering iron. The temperature regime should be the one at which the solder melts, tin or lead-tin, and is also produced by soldering. Fluxes should contain rosin or be made on its basis; soldering oil or even rosin itself can be used.
The surface of the wire is cleaned of dirt and oxide film, after which the parts pass. This process involves applying a thin layer of flux or rosin to the heated copper, and then the solder, which is distributed over the surface as evenly as possible with the help of a soldering iron. Parts that need to be connected are connected and heated again with a soldering iron until the solidified solder melts again. When this happens, the soldering iron is removed and the connection is cooled.
Details can be clamped in a vice so that the distance between them was 1-2 mm. On the parts cause flux and heat them. To the gap between the heated parts bring the solder, which melts and fills the gap. The melting point of the solder for soldering in this way should be lower than the melting point of copper so that the parts are not deformed. The part cools down, then it is washed with water and refined, if necessary, with an emery paper to smoothness and uniformity.Back to table of contents
Soldering dishes or sealing holes in copper
When soldering dishes use pure tin, the melting point of which is higher than that of tin solder or with lead content. Sometimes for soldering large parts hammer soldering irons are used, heated on an open flame of a gas burner or blowtorch. In the future, everything happens according to the standard scheme: stripping, fluxing and tinning, connecting parts and heating with a soldering iron. It is for this soldering iron that the solder from pure tin is convenient.
Inside the fitting, as a rule, there is a border that prevents it from being pushed through the pipe. It can be removed with a coarse file, if the fitting needs to be put on the pipe beyond the one provided and in such a way to seal an unnecessary hole.
Back to table of contents
While the solder cools, you should not blow on the compound or even give it minimal physical exertion.
Safety Instructions for Copper Soldering
It should be borne in mind that the heat conductivity of copper is very high, as a result, it is not recommended to solder the parts, holding them in your hands without protection, most likely it will end in burns. Items shorter than 30 cm are held exclusively with pliers or in protective gloves. If during the process of soldering to the exposed parts of the body, a flux drops, it is necessary to immediately wash it off with soap and water, since, in addition to the thermal one, a chemical burn can be made.
In any work with open fire and red-hot metal, as well as flux that contains acid, synthetic clothing is undesirable, since such a fabric ignites and melts much faster than others. Be sure to air during operation, the smoke from the burnt flux is harmful.
If there are no soldering skills at all, it is advisable to practice on scraps of pipes or wires before performing responsible work. There are few difficulties in this work, and 2-3 times, as a rule, it is enough to learn all the basic techniques. If the plumbing system is going, it is recommended to pre-assemble it on the floor before installing everything in its place. After assembly and soldering, the system should be thoroughly rinsed with hot clean water to remove parts of the flux and solder from the inside of the pipes.