What is the best flux for soldering aluminum? How to solder aluminum with soft solder

Aluminum and its alloys have very good characteristics, such as high thermal and electrical conductivity, ease of processing, low weight, and environmental safety. But this beautiful metal has one very big drawback: it is extremely difficult to solder. A properly selected flux for soldering aluminum helps solve this serious problem.

Properties of aluminum

The problem with soldering aluminum is due to its chemical structure. This metal itself is chemically very active; it reacts with almost all chemicals. This causes pure aluminum to instantly react with oxygen in air. As a result, a very thin and at the same time extremely strong oxide film is formed on the metal surface: Al2O3. In terms of their properties, aluminum and its oxide represent two extreme opposites combined into a single whole. For example:

• The melting point of pure aluminum is 660 degrees. Aluminum oxide, or corundum as it is also called, melts at a temperature of 2600 degrees. Refractory corundum is used in industry as a refractory material.
• Aluminum is a very soft and ductile metal. Corundum has extremely high mechanical strength, which makes it possible to produce all kinds of abrasive materials from it.

Aluminum oxide turns ordinary soldering into a rather complex process. For its successful implementation, it is necessary to use specific methods and special aluminum solders and fluxes.

Metal soldering

The meaning of soldering any metal is that a special substance called solder is introduced into the space between the parts being soldered in a molten state. After hardening, the solder reliably binds two metal parts into a single whole.

When soldering aluminum, the oxide film on its surface prevents the molten solder from connecting to the metal. In other words, adhesion is impaired, and therefore the solder cannot spread over the surface of the metal and stick to it. This makes soldering aluminum almost impossible without the use of special means that partially remove the oxide from the metal surface and promote normal adhesion.

Removing oxide film

Removing oxide from the surface of aluminum is a complex process and never leads to a final result. That is, the oxide film is practically impossible to remove, since instead of the one just removed, a new one is instantly formed. It is possible only with the help of specific means to weaken its effect. This can be done using two different methods:

• Chemical method. With the help of special aluminum fluxes, the film is destroyed as a result of exposure to active acids.
• Mechanical method. Through the use of abrasive tools, the integrity of the film is damaged.

In practice, both of these methods are most often combined to achieve the maximum possible effect.

Fluxes for aluminum

Flux is used to remove oxide from the metal surface and subsequently prevent the formation of a new film. It must be remembered that during the soldering process, the flux should not interact with the solder and enter into chemical reactions with it. Fluxes can be in different states:

• Liquid.
• Paste.
• Powder.

For aluminum, liquid fluxes based on orthophosphoric acid are most often used.. There are so-called no-clean fluxes, the use of which does not require subsequent washing of the soldered surfaces under running water. However, most often aluminum fluxes contain highly toxic substances that are unsafe and, from an environmental point of view, can severely corrode the metal at the soldering site. Therefore, the use of fluxes requires thorough washing of the soldering area under running water. The industry produces a larger number of aluminum fluxes, among which the following can be distinguished::

• F-64. Highly active flux for aluminum and its alloys. It is considered the best flux for this metal. High activity is determined by the high content of active fluorine in its composition, about 40%. When heated, fluorine destroys the oxide film on the surface of aluminum. The use of this flux requires thorough washing of the welded surfaces after the process is completed.
• F-34A. Special aluminum flux for refractory solders. Ingredients: potassium chloride 50%, lithium chloride 32%, sodium fluoride 10%, zinc chloride 8%.
• F-61A. It is used with conventional lead-tin solders, melting at a temperature of 150−350 degrees. Composition: zinc fluoroborate 10%, ammonium fluoroborate 8%, triethanolamine 82%. Used for soldering dissimilar metals, such as aluminum and copper. Therefore, when the question arises of how to solder aluminum to copper, this flux will be the answer.
• NITI-18 (F-380). Suitable for refractory solders with a melting point of 390 - 620 degrees. The peculiarity of this flux is that, while dissolving the oxide film well, it has virtually no effect on the base metal. After finishing soldering, flux residues must be removed immediately. To do this, the soldering area is first washed with hot running water, then with cold water. And finally, incubate for 15 minutes in an aqueous solution of phosphoric anhydride.
• A-214. Universal no-clean flux of medium activity. Application temperature 150−400 degrees. It does not contain harmful salts of aniline, phenol or carboxylic acids, therefore, thorough rinsing is not required after use. Residues can be easily removed with a paper towel soaked in alcohol.

Mechanical oxide removal

To facilitate the dissolution of the film using flux, it is first partially removed using mechanical methods. These techniques make it possible to only slightly weaken the effect of the oxide, since it was experimentally established that the newly formed film is somewhat inferior in strength characteristics to the old one. For these purposes the following devices are used:

• Sandpaper.
• Files and rasps.
• Hard metal brushes.

The process of mechanical removal of surface oxide can be optimized using brick dust. The soldering area is first sprinkled with fine brick chips. Then:

As an abrasive, with the same effect, you can use sifted river sand or metal filings.

Soldering aluminum

The basis of any soldering is the so-called tinning or tinning. In this process, solder is distributed evenly over the surface of the metal. In order for tinning to go well, two important components are needed: a special flux and properly selected solder. We have already looked at fluxes, now it’s the turn for solders.

Special solders

Conventional solders used for soldering non-ferrous metals contain tin and lead. The question of how to solder aluminum with tin is not relevant, since such solders are not recommended for aluminum, because it is practically insoluble in these metals. Special solders are used that contain a fair amount of aluminum itself, as well as silicon, copper, silver and zinc.

• 34-A. Special refractory solder for aluminum. Melting point 530−550 degrees. Composition: aluminum 66%, copper 28%, silicon 6%. It is recommended to use it together with the corresponding flux F-34A.
• TsOP-40. Belongs to the category of tin-zinc solders. Composition: zinc 63%, tin 36%. Melting occurs within 300−320 degrees.
• HTS 2000. Special solder for aluminum made in the USA. Main components: zinc 97% and copper 3%. Melting point 300 degrees. Provides a very strong connection, comparable in strength to a weld seam.

The presence of a metal such as zinc in the solder provides it with high strength characteristics and good resistance to corrosion. The presence of copper and aluminum increases the melting point and makes the solder refractory.

The use of one or another solder is determined by the tasks facing the parts being soldered. Thus, for soldering large-sized and massive aluminum parts, which will subsequently be subjected to heavy loads, it is better to use refractory solders; their melting temperature is comparable to the melting temperature of aluminum itself. When the question arises of how to solder an aluminum tube, you need to understand exactly what this tube will be used for in the future. Refractory solders are characterized by high strength, and the large mass of the part allows for good heat dissipation during the soldering process, which will prevent the destruction of the aluminum structure due to its melting.

Process Features

Soldering aluminum is no different from soldering any other non-ferrous metal.

At home, aluminum soldering can be divided into two types:

• High temperature soldering of large parts. As a rule, this is thick-walled aluminum of large mass. The heating temperature of the parts is 550−650 degrees.
• Low-temperature soldering of small household items and wires for electronic installation. Soldering temperature 250−300 degrees.

High-temperature soldering involves using a gas burner running on propane or butane as a heating element. But when the question suddenly arises of how to solder aluminum at home, you can just as easily use a blowtorch.

In the case of high-temperature soldering, it is necessary to constantly monitor the heating temperature of the surfaces being soldered. For this purpose, use a piece of refractory solder. As soon as the solder begins to melt, this indicates that the required temperature has been reached and heating of the part must be stopped, otherwise it may melt and subsequent destruction of the entire structure.

For low-temperature soldering, an electric soldering iron with a power of 100 to 200 watts is used, depending on the size of the parts being soldered. The larger the part, the more powerful the soldering iron will have to be used to heat it up. At the same time, a 50-watt soldering iron is quite suitable for soldering wires.

In both cases, both with high-temperature soldering and with low-temperature soldering, the stages of the process are approximately the same and consist of the following sequential steps:

• Mechanical processing of the future soldering area. It is carried out using all kinds of abrasive means. Purpose: to weaken the surface oxide film and make it more susceptible to flux.
• Degreasing the soldering area using organic solvents such as alcohol, acetone, gasoline.
• Fixing parts in the desired position.
• Applying flux to the surfaces to be soldered. If liquid flux is used, it is best to apply it with a brush.
• Warming up the soldering area using an electric soldering iron or gas torch.
• Applying molten solder to the soldering area and tinning metal surfaces (distributing the solder in an even layer).
• We connect the metal surfaces and fix them in the appropriate position.
• After that. Once the solder has cooled and the parts are soldered, we wash the soldering area under running water in order to wash away any remaining flux.

Craftsmen have no difficulty soldering copper, brass and steel wires and parts, but if they have to deal with aluminum surfaces, the solder does not even stick to the product, and soldering turns into torture. The difficulties are caused by the fact that a thin but very strong film of Al2O3 oxide forms on the surface of this metal. You can remove this film mechanically - for example, by cleaning the product with a file, but upon contact with air or water, the metal will immediately become covered with a film again.

Despite the difficulties that arise, it is possible to solder aluminum products. There are several ways to solder aluminum.

Soldering aluminum alloys

Excellent results can be obtained using the following alloys:

• two parts zinc and eight parts tin
• one part copper and 99 parts tin
• one part bismuth and 30 parts tin

Before soldering, both the alloy and the part itself must be well heated. It should also be remembered that soldering acid must be used with this soldering method.

Soldering aluminum using special fluxes

Standardly used fluxes do not dissolve the oxide film on the surface of aluminum, so special active fluxes must be used.

Flux for soldering aluminum is used to work with tin-lead solders at an operating temperature of 250-360 degrees. This flux, both during soldering and tinning, removes the oxide film well, cleans the metal surface and, as a result, the solder spreads better over the surface. All this leads to the creation of a more dense and durable connection of the fused parts. Excess of this flux is easily removed with solvents, alcohol or special liquids.

Other methods of soldering aluminum

There are also non-standard ways to solve this problem, for example:

• The soldering area on the aluminum product is thoroughly cleaned and a couple of drops of concentrated copper sulfate are applied. A small piece of copper wire is stripped, rolled into a circle with a diameter equal to the soldering area, and the free end of the wire is connected to the “plus” terminal of the 4.5 volt battery. A piece of wire with a folded circle is dipped in a small amount of copper sulfate. The negative of the battery must be connected to a part on which, after some time, a certain layer of copper will settle. After drying, you can weld the necessary parts or wires to this place in the usual way.
• In this case, abrasive powder is used, mixed with a small amount of transformer oil to form a liquid paste. This paste is applied to cleaned soldering products. Next, the soldering iron is well tinned and rubbed in these places until a layer of tin is released on the surface. Then the parts are washed and then soldered using the usual method.
• For this method you will need a transformer. Its minus is connected to the product, and a large-section copper wire consisting of smaller conductors is connected to the plus. If you connect this wire to the future soldering site for a short time, micro-soldering of copper and aluminum will be performed, which will subsequently allow soldering of wires using the usual method. To simplify the process, you can use soldering acid.

Soldering aluminum utensils (without a soldering iron)

Aluminum cookware is in definite demand among housewives, but sometimes it breaks down, and in order not to buy a new one (which costs a lot), you can repair such products by soldering without a soldering iron. The method below is suitable for sealing small holes (up to 7 mm in diameter).

1. It is necessary to clean the soldering area to a metallic shine using sandpaper or a file. If the dishes are enameled, then the enamel must be removed within a radius of 5 millimeters around the hole to be sealed. To do this, the enamel is removed from the dishes by lightly tapping with a hammer. Then the metal must be cleaned.
2. The soldering area is lubricated with soldering acid or covered with crushed rosin. A piece of tin is placed on the inside of the hole, and then the container is heated over the fire of the stove. If the dishes are enameled, then it is better to heat them over an alcohol lamp - this gives more targeted heating, and therefore the rest of the enamel will not crack from the high temperature.
3. When heated, the tin melts and tightly closes the hole in the dish. In this case, the help of a soldering iron is not required.

Hello my dear readers! I became interested in aluminum soldering about 5 years ago, when I urgently had to solder the cooling radiator of my Grasshopper. Below I will show a photo of it and the place of soldering on the radiator, which is still working. Recently I was asked what is the best way to solder aluminum? I decided to read all the relevant articles and personal opinions on aluminum soldering and put it on one page. This is how this article was born. Go!

Why is aluminum difficult to solder?

Anyone who has tried to solder aluminum knows that ordinary solder does not stick to it at all. This is all due to a stable film of aluminum oxide, which has poor adhesion to solder. Moreover, this film covers aluminum and its alloys very quickly. Before you have time to clean it, the light metal has already oxidized. Therefore, all methods of aluminum soldering first deal with the film, and then take care of adhesion.

Aluminum oxide (Al 2 O 3) in mineralogy is called corundum. Large transparent corundum crystals are gemstones. Due to impurities, corundum comes in different colors: red corundum (containing chromium impurities) is called ruby, and blue corundum is called sapphire. Now it is clear why the oxide film does not solder at all.

How to remove oxide film?

The aluminum oxide film is removed in two ways: mechanical and chemical. Both methods remove aluminum oxide in an airless environment, that is, without access to oxygen. Let's start with the most difficult, but most correct and reliable method of removal - chemical.

Precipitate copper or zinc

The chemical soldering method is based on the preliminary deposition of copper or zinc onto aluminum by electrolysis. To do this, apply a concentrated solution of copper sulfate to the desired location and connect the negative of the battery or laboratory power source in a free place. Then take a piece of copper (zinc) wire, connect a plus to it and immerse it in the solution.

Through the process of electrolysis, copper (zinc) is deposited onto the aluminum and adheres to it at a molecular level. Then aluminum is soldered on top of the copper. True, it is not clear how all this passes through the oxide barrier. I think that this instruction skips the step of scratching aluminum under a film of copper sulfate or other chemical exposure. Although the practice from the video below shows that you don’t have to scratch.

After deposition, copper or zinc can be processed without problems using standard fluxes. It seems to me that this method makes sense to be used on an industrial scale and for particularly critical work.

Use oil without water

The second most difficult method is to remove aluminum oxide. In this case, the oil should contain a minimum of water - transformer or synthetic oil will do. You can hold the oil at a temperature of 150 - 200 degrees for several minutes so that the water evaporates from it and it does not splash when heated.

Under the oil film, you also need to remove the oxide. You can rub it with sandpaper, scratch it with a scalpel, or use a serrated tip. When I needed to solder the engine cooling radiator, I used the chip method. We take a nail, saw it with a file to get steel shavings.

Next, apply oil to the soldering area and sprinkle chips. Using a soldering iron with a wide tip, we try to rub the soldering area so that there are shavings between the tip and the aluminum. In the case of a massive radiator, I additionally heated the tinning area.

Then we take a drop of solder onto the tip, immerse it in oil at the soldering site and rub it again. For better tinning, you can add rosin or other flux. The so-called surfacing under a layer of flux occurs. The video shows a good example of soldering aluminum with oil.

Solder with active flux

There are separately developed active fluxes for soldering aluminum. They usually contain acids (orthophosphoric acid, acetylsalicylic acid) and salts (sodium salt of boric acid). Strictly speaking, rosin also consists of organic acids, but in practice it gives a weak result on aluminum.

Due to their activity, acid fluxes must be washed off after soldering. After the first wash, you can additionally neutralize the acid with alkali (soda solution) and wash it a second time.

Active fluxes give good and quick results, but inhaling the vapors of this flux is strictly prohibited. Vapors irritate mucous membranes, damage them, or can enter the bloodstream through the respiratory tract.

Fluxes for aluminum soldering

Let's look at all the common fluxes for soldering aluminum.

Rosin

Liquid fluxes are good because they can be applied in a thin layer. They evaporate more actively and often have scalding vapors. More suitable for soldering with a soldering iron.

• Flux F-64 contains tetraethylammonium, fluorides, deionized water, wetting additives and corrosion inhibitors . It is capable of destroying a strong oxide film of considerable thickness, which means it is suitable for soldering large workpieces. Suitable for soldering aluminum, galvanized iron, copper, beryllium bronze, etc.
• Flux F-61 contains triethanolamine, zinc fluoroborate, ammonium fluoroborate. It can be recommended for low-temperature soldering at 250 degrees or tinning of products made of aluminum alloys.
• Castolin Alutin 51 L contains 32% tin, lead and cadmium. This composition works best when using solders from the same manufacturer at temperatures of 160 degrees and above.
• There are also, but I won’t list them - they should all be equally good.

Solder for soldering aluminum

Solder HTS-2000

This is the most advertised solder. Soldering aluminum with it is very simple. Watch the promotional video about soldering HTS-2000 from New Technology Products (USA). They say it is even better and stronger than aluminum. But it is not exactly.

And here is the real experience of soldering with HTS-2000 solder. The solder doesn't stick well at first, but then it seems to work. A pressure test showed that the soldering area was etching. There is an opinion that HTS-2000 should only be soldered with flux. Draw your own conclusions.

Castolin solder

Solder Castolin 192FBK consists of aluminum 2% and zinc 97%. 192FBK is practically the only solder for soldering aluminum to aluminum in the list of offers of the French company Castolin. There is also AluFlam solder 190, but it is designed for capillary soldering and does not have flux inside. The line also includes Castolin 1827 solder, designed for soldering aluminum with copper at a temperature of about 280 degrees.

Castolin 192fbk tubular solder contains flux in the core, so you can solder without the recommended Castolin Alutin 51 L liquid flux. The video below shows the soldering process. Good solder - you can buy it for 100 - 150 rubles. per rod weighing 10 grams.

Solder Chemet

Solder Chemet Aluminum 13 used for welding aluminum and its alloys with a melting point above 640 degrees. It consists of 87% aluminum and 13% silicon. The solder itself melts at a temperature of about 600 degrees. Cost - about 500 rubles. for 100 grams, in which there are as many as 25 rods.

Its older brother Chemet Aluminum 13-UF has flux inside the tube, but costs more - 700 rubles. for 100 grams and 12 rods.

I didn’t find any sane videos on soldering with this solder. Of course, this list of solders is not exhaustive. There are also Harris-52, Al-220, POTs-80, etc.

Domestic solders

• • . Why not? When I was soldering an aluminum radiator, this was the only one I had on hand. And it has held up well for 5 years.
  • Aluminum solder 34A- for soldering with a gas-flame torch, in a furnace in a vacuum or with immersion in a melt of aluminum salts and its alloys, except for D16 and containing > 3% Mg. Melts at 525 degrees. Solders aluminum alloys AMts, AMg2, AM3M well. For 100 grams you will have to pay about 700 rubles.
  • Solder grade A— manufactured in accordance with TU 48-21-71-89 and consists of 60% zinc, 36% tin and 2% copper. Melts at a temperature of 425 °C. 1 rod weighs about 145 grams and costs about 400 rubles.
  • SUPER A+ used with SUPER FA flux and manufactured in Novosibirsk. Positioned as an analogue of HTS-2000. For 100 grams of solder they ask for about 800 rubles. There are no reviews yet.

Comparison of solders for aluminum soldering

In this video, the Master compared HTS-2000 solder with Castolin 192fbk and domestic aluminum solder “Aluminum Cucumber”. The cucumber is practically made of aluminum, so its strength is high, but it must be soldered in a stove. Reviews of HTS-200 solder are extremely negative, but Castolin 192fbk solders well and has good wettability when heated.

Another Master compared HTS 2000 with Fontargen F 400M flux and Castolin 192FBK solder.

The results are:

• HTS 2000- solder is malleable, you have to resort to steel tools to level the solder over the metal surface. The situation with flux is much better.
• Castolyn 192FBK- high fluidity and wicking. Small holes are soldered with it quickly. It is difficult for them to solder large holes - it may fall inside the radiator.

Cored wire

Flux cored wire - needed for welding aluminum, not for soldering. Don't confuse these two concepts. The advantage of this wire is welding without the use of gas. This is electric welding for aluminum. An interesting thing, but expensive. I'll show you a good video about flux-cored wire welding.

Soldering iron for soldering aluminum

Soldering aluminum using a soldering iron must take into account the area of ​​the parts being soldered. Aluminum, like copper, is a good conductor of heat, which means more heat should come from the soldering iron than the parts being soldered dissipate.

An approximate calculation is 1000 sq. cm aluminum can effectively dissipate about 50 W of thermal power. It turns out to solder two parts with a total area of ​​1000 square meters. cm, you need to take at least. Then soldering aluminum will be fast enough so as not to turn into torture.

You can also solder with a low-power soldering iron. For example, when I soldered the radiator of my Grasshopper with a 60 W soldering iron, a hot-air soldering station helped me, which acted as a heater.

Aluminum soldering torches

When the power of the soldering iron and heating are not enough to solder, for example, thick aluminum sheets, then they come to the rescue.

I have already written a separate article about burners -. The power and size of the burner nozzle also depends on the areas that need to be heated. The advantage of the heating pad is the contactless delivery of heat and high heating speed. Often the edges of the workpiece do not have time to heat up, and the joint is already soldered.

Observe safety precautions when working with burners!

Here's what you can do with a simple canister torch.

What is better - welding or soldering aluminum?

The debate over the answer to this question is not going to subside. It turns out it all depends on your purpose. More precisely, the purpose of your connected parts.

If you need to solder a car radiator, then soldering aluminum is better suited because it is cheaper. For critical work (load-bearing structures) and food containers (for example, a milk flask), welding is better suited because it is more reliable. This is how I would formulate the answer to this question.

It is clear that it is easier for a master with gas welding to weld a radiator, rather than solder it, and vice versa - it is easier for a master with a soldering iron to solder.

Now look at TIG welding for beginners. Very helpful and well filmed.

How to make money soldering aluminum?

And now the most interesting thing is how and how much to earn from soldering aluminum. I opened Avito and searched cost of aluminum soldering work. Here's what happened:

• soldering of a car radiator, refrigerator, air conditioner - from 1000 rubles.
• soldering of electrical wiring - 15 rubles. for soldering.
• repair of bicycle frames - from 500 rubles.
• soldering of aluminum for food, for example, pans - from 100 rubles.

Expenses:

• Gas cartridge with burner 700 - 1000 rubles.
• Solder Castolin 192FBK - 150 rub. per bar * 5 = 750 rub.
• Training radiator - free or for 500 rubles. in scrap metal.
• Desire is priceless!

Business plan:

1. Spend 2000 rubles. for tools and experience
2. Recover the costs for 2 repairs.
3. There will still be at least 3-4 repairs left.
4. Profitability 200 - 300%!

And now what was promised. This is what my radiator looked like.

At this point, the fan casing bent due to heat and began to rub against the radiator. Three holes formed through which antifreeze leaked. I remember this night. It's good that it was within the city limits.

In the entire Rostov region I saw only one such machine. Once in the city of Kamensk-Shakhtinsky, she and I stood at a traffic light one behind the other. It looked funny.

That's all. I hope that now soldering aluminum is not something special for you. Master Soldering worked for you. What do you use to solder aluminum?

• Methods for preparing material
• Aluminum soldering process
• Tips for soldering at home

It is carried out by many self-taught masters. Every man can find a soldering iron in his house, since he cannot do without this tool. In production, as well as at home, in order to solder aluminum, it is necessary to use special materials and devices. This type of soldering can be done using tin-lead solders 50 and 61. If you are going to carry out this type of work at home, this can be done in several ways and with different materials.

Scheme of preparation for soldering aluminum.

Remember that the main task is to remove the oxide film from the metal surface, and direct contact with air should not be allowed; to do this, use rosin, mineral oil or alkaline, and you can also use a saturated solution of copper sulfate. In order to begin to consider the processes of soldering aluminum at home, you need to know some ways to prepare the material for this process.

Methods for preparing material

For the first method, rosin is used to clean the soldering area. And after that, the soldering iron is immediately connected to work, with the help of which you press the sandpaper to the place of soldering. Then you need to wipe the soldering area with sandpaper. Now it's time for the aluminum patch, which you can solder in the usual way.

Although rosin is often used in this processing method, mineral oil for a sewing machine is best.

Second cleaning method. In the place where something needs to be soldered, iron filings are additionally added to the rosin. Using this mixture, a heated soldering iron rubs the area so that the solder is as effective as possible. This effect occurs due to the fact that metal filings remove oxide from the surface, and this ensures maximum adhesion between surfaces. This method does not require additional metal cleaning.

Soldering iron circuit diagram.

The third cleaning method is labor-intensive and will take you a lot of time. But it is considered the most reliable. First, you need to treat the required area to remove the oxide film. Then, in the place where soldering will be carried out, it is necessary to create a plastic side, which will later serve as a bath.

You can make this bath from ordinary plasticine. It is necessary to apply a layer of copper sulfate to its bottom. Just remember that the tray is used where there is a large soldering area, and for minor damage you do not need it at all.

Now the bare copper wire is placed in this device. Its diameter is about 3 mm. Just remember that the wire should consist only of copper. The wire must be kept at a distance of one millimeter from the working surface.

To do this, use some kind of additional stand, and the wire that is in the bath must certainly create contact with the body. Then make contact with some current source, the voltage should be from 3 to 12 W.

You can do all this with the help of two connecting ends, and the power source can be a battery, a rectifier, or an ordinary battery. You need to provide all this with a light bulb, which will be responsible for the rated DC voltage.

It will light up when the aluminum surface comes into contact with a copper wire that is lowered into the bath. If the light goes off, it means the wire has touched the bottom of the bath, and if not, then the whole process is interrupted.

After this, the copper sulfate should come to a boiling state, and at this moment red copper sulfate is formed. You must wash and dry the red layer. Feel free to proceed with ordinary soldering of the surface.

How to solder aluminum?

Return to contents

Tools and materials for soldering.

Materials and tools:

• rosin;
• soldering iron;
• mineral oil;
• metal filings;
• copper sulfate;
• plasticine;
• welding pencil;
• lighter;
• piece of glass.

A welding pencil resembles a sealant solder, thanks to it you can get a strong and reliable connection of parts, wires, and aluminum tubes. Many people refuse simple gas torches, and are increasingly inclined to use a welding pencil.

But you need to take into account that the operation of different devices has its pros and cons. The operating process of this type of tool is very simple; for this you need to set fire to a pencil.

For this kind of manipulation, a simple lighter is suitable, with which you will set fire to the edge of the solder. The device will burn due to magnesium, which is included in its composition. It heats up to the temperature required to melt the aluminum.

Under the influence of high temperature, a molten mass appears. You need to apply it to your work surface. The angle of impact of the pencil does not matter, since the resulting mass adheres very well to the aluminum.

After the solder is soldered from the working surface, the pencil stops working, but the aluminum mass continues to burn. After about 20 seconds, the entire surface will be at the same temperature.

And after that, you can safely start filling the aluminum into the work surface. Use a pencil or a piece of glass for this purpose.

Return to contents

For those who are just planning to purchase a soldering iron, you need to know that you should try to choose a model that has a tip change function. Every time before starting work, check the tip: if it is very dirty, clean it with a file. It is very convenient to use pieces of wood or cardboard for this; this method is suitable if there are contaminants from flux, dust or oxide.

If your soldering iron is hot, it is not recommended to leave it dry; to do this, you need to place it in rosin. Under no circumstances should solder be stored in a metal box, lid or jar, since when it falls on a metal surface, it immediately sticks.

In order for the solder to be of high quality, it is necessary that the soldering surfaces be of the same temperature.

To change the temperature of the soldering iron, you just need to change the length of the tip. The most convenient option would be to change using a special adjustable device. If your soldering iron has heated up to a temperature of 260, maximum 300 degrees, then the process time should not exceed five seconds.

expertsvarki.ru

Soldering aluminum at home with a soldering iron

Flux for soldering aluminum

Once upon a time, I thought that aluminum soldering was done in factories and was not done at home. However, over time, this misconception has dissipated. This article is about how to solder aluminum at home and what to use to solder aluminum.

At school, the topic of aluminum was previously discussed in chemistry and physics lessons about its properties; it has excellent electrical conductivity and thermal conductivity, but is very difficult to solder. The difficulty of soldering it is due to the fact that an oxide film instantly forms on the cleaned surface, which is very resistant to various aggressive environments.

Once upon a time I came across such information that soldering is carried out with a solder consisting of tin and zinc or tin and bismuth. However, practice shows that it can be soldered quite normally with conventional POS 40 and POS 60 solders. It doesn’t matter what you solder with, the main thing is how.

The mechanical strength of such soldering is small, but what is mainly required is not the strength, but the electrical conductivity of the joint. I can’t say what else can be used to solder aluminum besides these solders; I haven’t tried it. You can also solder with lead, the main thing is that the soldering iron has enough power and heats it up to a sufficient temperature.

As mentioned above, aluminum has increased thermal conductivity, which is why cooling radiators are made from it. Therefore, for soldering large elements, the power of the soldering iron should be high, 100 - 200 W. If, of course, these are two small wires, then perhaps 60 - 100 W will be enough power.

Nowadays there are no problems with the choice of means, but previously I had to use anything to tin aluminum - aspirin, technical petroleum jelly, grease. For soldering aluminum at home, I chose two good fluxes F-64 and FTBf - A. The FIM flux also has good results. This is perhaps the most important thing, the better the flux, the easier the soldering.

The main thing is not to run into a fake, and there is enough of that now. you buy this “Flux for soldering aluminum”, but it’s no good. By the way, regarding the question of what else can be used to tin aluminum, there is such a flux F-34, this can be said just by its composition that it is aspirin. Aluminum can also be tinned with soldering oil.

Tinning methods

With good flux, the process of tinning and soldering is not a problem. It’s another matter if you don’t have one at hand, here the process becomes more labor-intensive.

The most important thing in the tinning process is to prevent contact of the surface being cleaned with oxygen. Therefore, the surface to be cleaned is thickly lubricated or filled with flux, and if necessary, it can be heated a little. You can simply, if the product is small, for example wires, clean them directly in the solution, pouring it into something.

Regarding the method of soldering aluminum with a soldering iron with a rosin solution, I did something like this. I pre-cleaned the surface, lubricated it with a solution and sprinkled it with copper or iron filings. Then, pressing with the soldering iron tip (the harder the better) and stripping off the oxide, I tinned it with regular solder.

Sometimes, if it was necessary to solder two wires, aluminum for example and copper, I used this method. I twisted the two ends of the wire and welded them with a current discharge using a graphite core from a battery. For such “welding” I used a 6-12 volt transformer with a current of 3 amperes. We connect one end of the wire from the transformer to a twist, and screw the battery rod to the second (you can use a brush from the engine). When touched, an arc appears and the ends are soldered into a ball.

So soldering aluminum at home is quite possible and not such a difficult task. A little practice and that's it.

Also read with this article:

How to solder aluminum at home?

There is still no universal method for soldering aluminum at home. However, you can offer techniques that will allow you to do without the help of professionals.

Initially, it should be noted that all the methods that will be indicated in this article are suitable exclusively for household purposes (soldering a figurine or the handle of a pan). For industrial quality, it is recommended to contact Rosteccom.

Various aluminum soldering techniques

So, first of all, we need the following instrumental set:

• soldering iron (with a power of at least 100 W);
• copper shavings;
• tin solder;
• rosin;
• flux;
• emery for preliminary cleaning of the surface.

The main problem in soldering aluminum is its resistance, which is achieved using an oxide film. It occurs almost immediately after the metal surface has been cleaned.

It is for these purposes that rosin is needed. As soon as you have sanded the surface, you need to quickly fill it with straightened rosin. Next, it is recommended to use copper filings.

Using a specialized flux, you can further solder the required part.

Electrochemical soldering of aluminum

To do this you will need a solution of copper sulfate. Wires that are made of different metals (copper and aluminum) are often soldered in this way. Both wires must be coated with a solution of copper sulfate.

You will definitely need a power supply. It can also be of small technical denominations: from 5 to 12 V. Current strength is 1 A (preferably). The negative wire is connected to one wire, the positive wire to the other.

After some time, a weak adhesion forms at the contact site. Next you should proceed according to the classics. Fill it with rosin, tin it with tin, and solder it securely.

Experts say that hydrochloric acid can act as a more effective substitute for copper sulfate. However, the latter can be freely purchased at any gardening store. But hydrochloric acid (especially concentrated), as they say, is with fire during the day.

• Do you know how to solder stainless steel using tin solder?

• Recommendations for high-quality electrical wiring connections - https://euroelectrica.ru/kak-soedinit-provodku/

A home craftsman will demonstrate in the video how to solder aluminum at home (literally on his knees):

How to solder aluminum with tin yourself

Soldering wire connections with solder is considered the most reliable method of connecting wires and cable cores. It’s good if you only need to solder copper wires, which are easily tinned with solder. It’s not for nothing that in electronics all terminals of elements are copper and tinned.

Soldering aluminum at home

Once solid wires and stranded cable strands are tinned, they are fairly easy to connect by soldering. How to solder aluminum with tin if the solder is rejected by aluminum oxide. As you know, aluminum is coated with a thin layer of oxide, which instantly forms on aluminum upon contact with oxygen. In order for the solder to adhere well to the aluminum wire, you need to remove the aluminum oxide and then tin it.

For this purpose, the following fluxes exist: soldering acid, special fluxes for aluminum, and a mixture of rosin and acetone. All these advantages destroy or hinder the formation of an oxide film on aluminum. After using this type of flux, the process of tinning aluminum is simplified.

The necessary tools for soldering aluminum with tin are: an electric soldering iron, a sharp knife, pliers for twisting wires, a small file for preparing the soldering iron tip. The materials you will need are: POS 61 or POS 50 solder, flux for soldering aluminum F-64 or similar, sponge.

Soldering aluminum with tin and flux F 64

Flux F 64 is intended for soldering aluminum. The soldering technique is not complicated. First of all, you need to remove 5 cm of insulation from the wires. The insulation is removed with a sharp knife at an angle to the wire so as not to cut it. Notched aluminum breaks off easily.

Tools and materials for soldering aluminum wire

Next, you need to thoroughly clean the wire with fine sandpaper or a sharp knife. Having stripped the wire, it is moistened with a brush with a plus and with a sharp knife they continue to strip the wire, but now under flux. In this way, the oxide film of the aluminum wire is removed, preventing it from oxidizing again in air. Next, using a heated soldering iron with solder, begin tinning the wire from its end.

If you start tinning the wire near the insulation, then you can burn it. In this case, the insulating properties of the wire will be lost. The wire is tinned with a soldering iron, moving back and forth, while the oxide film is removed from the aluminum. It is not possible to tin the wire straight away. Therefore, flux is again applied to the non-tinned sections of the wire and sections of the remaining oxide film are removed with a hot soldering iron with solder and movements back and forth and serviced.

In this way, the aluminum wire is completely covered with solder. After tinning, the aluminum wire is dipped in a soda solution (5 tablespoons per 200 grams of water) and the remaining flux is washed off with a toothbrush. The flux contains active acids that not only corrode the film, but also the wire itself. Therefore, the remaining flux must be washed off. It will not be possible to wash it off completely, since it partially remains under the solder and eats into the wire.

But at least partially it needs to be washed off. Copper wire is not treated with F 64 flux; it is better to use a solution of rosin and alcohol (50% to 50%). Using a brush, apply liquid rosin to the copper wire (having previously stripped it) and use a hot soldering iron to service the wire, starting from the end. The soldering iron tip should be smooth and clean. The shells at the end of the soldering iron tip are removed with a fine file.

And the remains of burnt solder (slag) are wiped off with a sponge or rag. Once the aluminum and copper wires are tinned, they are twisted with pliers, liquid rosin is applied with a brush and the connection is soldered, also starting from the end. If you connect aluminum without tinning with solder, the connection may break down over time. The aluminum-copper connection is a galvanic couple, and when current passes through it, it heats up and destroys the connection.

Table of temperature conditions of solder brands

As a result, the twisted area becomes very hot and charred, which increases the fire hazard. Tin solder is neutral to aluminum, so aluminum wires must be tinned before connecting to copper. POS 61 and POS 50 solders with a low melting point of 190 - 210C are well suited for soldering aluminum wires.

Soldering aluminum with copper, tin and rosin

Soldering electrical wires using soldering acid is prohibited in the PUE. This is due to the fact that this acid does not burn completely during soldering. As a result, the junction of the wires is corroded by acid over time, oxides are formed, which heat up when current passes and can cause the insulation to catch fire. These acid-containing fluxes include special fluxes for soldering aluminum, including F 64.

So how to solder aluminum with copper so that the connection is high-quality and durable. In terms of complexity, the method of tinning aluminum with tin and rosin is even easier than tinning aluminum with F 64 flux. But the quality and reliability when tinning with rosin will be high. When tinning aluminum in rosin, you need to make or select a low bath for liquid rosin (rosin 60% and alcohol 40%).

Fluxes for aluminum soldering

Fill the bath with liquid rosin so that the wire is buried in it with 5-10 mm of insulation. The wire, stripped of insulation, is placed in rosin and with a sharp knife (conveniently a scalpel) the oxide film is removed from the aluminum wire without removing it from the bath. That is, under rosin they protect the wire along its entire length from all sides. Under the rosin, a film does not form on the cleaned areas of the aluminum wire, since there is no contact with oxygen.

Now take a heated soldering iron with solder with a power of at least 60 W and lower it onto the bare and free of oxide wire, right at the surface of the rosin, little by little scroll and pull out the already tinned sections of the wire. The essence of the method is that the wire is tinned at the very surface of the liquid rosin. So that the stripped sections of the wire from oxide cannot come into contact with air.

The soldering iron can be immersed 2-3 mm in rosin at times. After tinning the wire a little, lift the soldering iron so that it heats up again. Yes, at the beginning, there will be a lot of smoke, so it is better to learn to solder outdoors or in a room with good ventilation. After several attempts, you will develop your own tinning technique and gain a little experience.

You will decide on the position of the soldering iron, the speed of tinning the wire will increase, that is, skill will appear, and the amount of smoke will decrease. But the wire will be perfectly tinned. Next, as usual, twist the wires and solder them with a small amount of solder.

The remaining rosin on the soldered twisted wires is washed off with a brush and alcohol. The disadvantage of this method is the impossibility of soldering in hard-to-reach places. For such cases, it is better to use other methods for safely connecting aluminum to copper.

How to determine phase zero and ground

Wiring Requirements

Electrical panel assembly

Soldering aluminum at home is a simple and safe activity

Home craftsmen quite often have to deal with the problem of repairs, as well as the manufacture of aluminum products. If there are no problems with mechanical processing (metal is easily sawed, turned and bent), then the process of connecting parts together causes difficulties.

We are not talking about welding, these are issues of large-scale repairs. Most often you have to solder parts in the traditional way.

• The most common problem is leaky dishes, or parts of household aluminum utensils that have fallen off. Bonding is not always suitable due to low heat resistance and poor aesthetics of the seam. Rivets cannot provide a tight seal. All that remains is soldering aluminum with tin.
• Another need for quality connections is electrical appliances. Quite often it is necessary to connect aluminum conductors to terminals, or simply to the surface of electrical equipment. Splicing wires will also be more reliable if there is a strong solder instead of twisting.

Like any metal, aluminum can and should be soldered. It has good ductility and thermal conductivity. But there is a problem with adhesion. In the open air, the metal is instantly covered with a durable film of oxides, which not only acts as a heat insulator, but it is almost impossible to apply solder to it.

Therefore, high-quality flux for soldering aluminum is the first assistant in your work. With its help, you can also solder aluminum to other metals.

General principles of soldering aluminum at home

1. The surface must be thoroughly cleaned of paint, dirt and greasy liquids
2. The soldering area is ground, it is advisable to level out all irregularities to the depth of the largest defect

There should be a minimum amount of time between cleaning and applying flux.

It is necessary to choose the right heating device according to the volume of metal

Aluminum has excellent thermal conductivity, the temperature is dissipated over the entire area, and the heated area will quickly cool down

Before soldering, aluminum must be tinned. No oxides are formed under the solder layer.

Little secrets. If you don’t have a special flux on hand, you can use abrasive protection against immediate surface oxidation:

• Rub the soldering area vigorously with a piece of brick. The resulting dust does not need to be blown off. Place a large amount of regular rosin on the soldering iron tip and pour it over the soldering area directly on top of the brick dust. Then tin the surface by pressing the soldering iron tip firmly onto the metal.

Using a flat cut, you need to rub the dust into the aluminum. The abrasive will remove the thin layer of oxide and provide a bond to the solder. You can use sifted fine sand.

Another way is to use iron filings. You can simply file down a thick nail with a medium-grit file. Pour liquid rosin onto the soldering area and cover it with sawdust. When the rosin hardens, put solder on the tip of the soldering iron and intensively rub it on top of the sawdust. The tin coating will provide instant protection against oxidation.

Use of transformer oil

Soldering aluminum at home is usually done with a soldering iron.

You can mix solder paste with transformer oil and apply it to the newly cleaned surface. Then rub the soldering iron vigorously until a stable layer of solder appears.

Important! Such work should be carried out with a hood or in a well-ventilated area. Overheated oil produces acrid smoke.

But there is an easier way. We process the future soldering area using fine sandpaper. Then, without delay, pour in the oil.

Once again, intensively rub the surface with sandpaper, after which we rub in the solder with force with a heated soldering iron.

We pry up the tin layer with a thin screwdriver to check the strength of the connection. If the edges of the solder come off the aluminum, repeat the procedure again. After obtaining stable tinning, both copper and aluminum wires can be soldered to this place.

What kind of solder is used for soldering aluminum?

The choice of solder is influenced by the method of joining aluminum parts.

1. If you are using a regular soldering iron, you need a material with a low melting point. Electrical connections typically use traditional solder. These are the following types of alloys: zinc-tin, copper-tin and bismuth-tin. They are better known to us as amateur radio solders of the POS series.

These alloys melt easily, and little heat from the soldering iron is transferred to them (which is important, given the high thermal conductivity of aluminum). In addition, such material is easy to buy at an affordable price. However, connections using low-melting solder have low strength. This method is only suitable for electrical installation.

If you soldered the spout to an aluminum kettle, or repaired a burnt hole in a pan, the connection will quickly collapse under the influence of high temperatures.

As a last resort, you can use the common refractory solder TsOP-40, consisting of tin and zinc. This connection holds the temperature quite well, but has low tensile strength.

For mechanically strong connections, refractory solders are used. In addition, they will not melt at high temperatures. The composition must necessarily include aluminum itself. The most common alloys are aluminum-copper-silicon.

Aluminum dissolves well in the other components of the composition, and will provide a connection with the workpiece at the molecular level. Copper will add ductility, and silicon will make the connection strong. The favorite solder of home tinkers is domestic composition 34A.

More expensive (this does not mean an increase in quality) is the imported “Aluminum - 13”. The advantages of such solders are that they can be used to qualitatively weld parts, which then work under load.

Of course, these solders do not reach the strength of arc welding, but repairing dishes with their help gives a good result.

However, aluminum-based solders melt at a temperature of about 600° C. This result cannot be achieved using a soldering iron.

For mechanically strong and heat-resistant connections, aluminum is soldered with a gas torch.

Attention! Despite the external similarity and quality of the connection, soldering with a torch has nothing in common with welding. Only the solder melts; the base metal of the workpiece remains solid during the entire process.

Advantages of soldering with a torch over welding in an argon environment:

1. There is no need to purchase expensive equipment. A hand-held gas torch is used for soldering. Such a tool can be purchased in tool stores, or even among tourist goods.

Electric welding, using any method, exposes the material to thermal stress. Foci of different tension in the metal appear; near the seam, the aluminum changes geometry. With high-quality soldering, the aesthetics of the connection remains at a high level

For connecting compact parts, especially those made of thin metal, there is simply no alternative to soldering

The work can be done at home - no sparks fly, no pungent smell of burning aluminum, no ultraviolet irradiation of the skin

You can easily control temperature conditions during operation by simply changing the intensity of the flame.

How to solder correctly using a torch

You cannot do without preparing the joint, just like when soldering with a soldering iron. The metal should be cleaned of dirt and sanded to obtain a smooth surface. Then you need to secure the parts using any jig - be it clamps or a vice.

When working with a burner, aluminum blanks will heat up over the entire surface. And given the high thermal conductivity of metal, there will simply be no place on the parts that you can grab with your hand, even with protective gloves.

The work area must be cleared of flammable objects and liquids. Provide intensive ventilation - even without caustic emissions, heated fluxes emit an unpleasant odor. Take care of fire extinguishing equipment.

It is necessary to prepare solder wire with a margin of length. You won't be able to use every single rod; 10% of the length is left to hold the solder. But stopping heating and going for new packaging is irrational.

Important! A better quality seam is obtained with continuous soldering. If you interrupt the process (forced), before continuing work, completely warm up the entire soldering area, including the already solidified solder. The same should be done when applying several layers. First, we warm up the frozen layer, then add the next one.

The burner flame is always directed away from you. There should be no objects in its path.

It is allowed to change the color of the aluminum billet to bright orange. The metal will not melt, and when heated to the maximum temperature, the solder will lie more evenly.

Be sure to use flux. There are proven compositions based on lithium and potassium chlorides, as well as zinc chloride. These are brands such as F-59A, F-61A, F-64A. For higher temperature soldering it is better to use F-34A. It contains sodium fluoride.

You can prepare flux for soldering aluminum yourself. However, this is not recommended, since it necessarily contains caustic substances. It is better to purchase a ready-made composition in the store.

Important! Inhaling flux vapor while soldering is very harmful. Use a respirator or portable hood.

Soldering aluminum at home

A large range of parts, products, devices made of aluminum and its alloys predictably provides work for specialists in assembling such products using welding and soldering; or, if necessary, their restoration and repair.

Parts can also be connected using mechanical methods - rolling, cold welding, using rivets, screws and bolts.

Let's take a closer look at soldering at home.

Difficulties in soldering aluminum

• The thermal conductivity of aluminum is very high, so preheating is required before soldering or a more powerful heat source during the process itself.
• Dense and very refractory oxide, which necessarily covers the surface of any product made of aluminum or aluminum alloy with its film, makes it difficult to solder edges and is a source of contamination of the seam with its particles.
• The material's tendency to deform and warp is twice as high as for similar steel products. This is explained by the low elasticity of aluminum with large linear expansion.
• When overheated, the strength of the metal drops so sharply that hard sections of the edges may fail under the weight of the weld pool. Another disadvantage of overheating is the possibility of leakage of liquid aluminum. The moment of overheating cannot be tracked due to the absence of changes in the color of the metal at this time.
• The connection weld is prone to cracking due to its columnar, rough structure and the high (almost 7%) shrinkage of aluminum during casting.
• The need for thorough mechanical cleaning and maximum degreasing of the soldering area.
• The required flux with solder is not always available (in stock) at home.

Advantages of home soldering

• Without being a qualified specialist, such work can be performed efficiently with appropriate preparation for the soldering process;
• the work process takes little time, it can be stopped or resumed at any time;
• no expensive special industrial equipment is required; You only need a soldering iron, gas torch or blowtorch, and, if necessary, a vice or clamp;
• ability to work with wires, pipes and workpieces (of various geometries, weights, thicknesses);
• ease of machining of aluminum parts with available household tools (file, needle file, metal brush, sandpaper, sharpening or abrasive wheel) in preparation for soldering;
• the ability to replace (in some cases) special fluxes and solder with available ones, available in stock, with minor losses in soldering quality.

Soldering methods

1. Soldering with solder paste. The paste is distributed evenly along the joint line. After melting using a gas burner, it spreads and forms a connecting seam.

2. The most basic and accessible method is soldering with a special pencil. Containing magnesium, the pencil can be easily ignited from any open flame source. The molten mass obtained at the edge of the pencil when heated is applied at the joints. “Drawing” with a pencil is convenient and easy at any angle.

3. Classic soldering. having its own characteristic features due to the metal being connected:

• Conventional solders with a tin-lead base (PLC) will not provide high reliability to the connection due to the insolubility of aluminum itself in these metals. The result is achieved by using solder with a base of silicon, zinc, copper, aluminum and other metals. Some solder grades are 34A, P-300-A, V-62, P-425-A. The strength of the resulting joint and its corrosion resistance increases with increasing zinc content in the solder used.
• When soldering, you will need strong active fluxes marked on the packaging “for aluminum soldering” (for example, 34A, F61A, FTKA).

Tools and materials

• soldering iron, gas torch or blowtorch;
• solder;
• flux;
• plasticine - to create an obstacle to the flow of molten metal.

Sequence of work

• prepare metal for soldering - mechanical cleaning and degreasing;
• if necessary, fix or compress parts;
• using flux, tin the surfaces to be soldered and the soldering iron tip itself;
• heat the connection;
• perform soldering by melting the solder in small parts so that it spreads evenly;
• After the joint has cooled, check the quality of the resulting seam.

Soldering modes

Safety

When performing soldering work, you must strictly monitor fire safety when working with a hot power tool or a burner with an open flame. Prepare a stand in advance or set aside a place for a hot tool. Provide good ventilation or exhaust over the soldering area.

• The workpieces should be positioned or clamped taking into account the horizontal position at the soldering site to prevent the molten solder from flowing off.
• The selected solder should have a melting point lower than the base material of the workpiece.
• Fluxes can be for low- and high-temperature soldering - pay attention to the label and make a choice for your specific operating conditions.
• Soldering with a pencil reduces the quality of the connection.
• High-temperature solder and flux are usually used when soldering massive products.
• If aluminum is connected by soldering to another metal, solder and flux suitable for both metals are selected.
• It is imperative to clean the surfaces of parts before soldering - the oxide cannot be completely removed, but the thickness of its film will decrease, which will make the task easier for the flux.
• You can protect against overheating of aluminum and its melting using solder. By periodically touching the heated surface with it, you need to catch the moment when it begins to melt - the desired temperature has been reached.
• The same temperature of all surfaces prepared for soldering has a positive effect on the quality of the connection.
• A soldering iron with interchangeable tips of different lengths is very convenient for changing the temperature in the soldering zone.
• Without special solder and flux, soldering aluminum is a troublesome process that does not always guarantee results. But in the absence of an alternative, it is still worth trying to solder the surfaces with ordinary tin-lead solder. The flux is replaced by molten rosin, which covers the soldering area, protects it from air access and prevents the re-formation of the oxide film. The soldering iron tip begins to rub against the rosin-coated surface. Mechanical destruction of the oxide film and tinning of the part occurs. Cleaning surfaces will be more effective if you add regular metal filings to the rosin. The tinned surfaces are connected and heated until the solder begins to melt.
• Before starting work, clean the dirty soldering iron tip.

Attention, TODAY only!

linochek.ru

How and with what to solder aluminum at home?

Until recently, aluminum was perhaps the most common “electrical” material. Significantly cheaper than copper, it has good electrical properties. That’s why all the wires of high-voltage lines are made from it: light, good conductor, ductile, low-oxidation.

You can solder aluminum. Although wires made of this metal can be easier to connect in other ways: through screw terminal blocks, by welding. Often in junction boxes the aluminum wires were simply twisted tightly. This method was used when apartments usually did not have particularly high energy consumption.

But now, with the saturation of the market with powerful and varied household appliances, it is necessary to bring the entire household power supply network to a quality that would be oriented towards serious energy consumption, approaching industrial consumption. And in this case, it is better to solder aluminum at home than to twist it.

Properties of aluminum as a metal and conductor

Aluminum stands in the periodic table immediately behind sodium and magnesium - active metals, even flammable in air. Therefore, it is a light and very active metal. Its thermal and electrical conductivity is lower than that of copper. But since aluminum is lighter than copper, products made from it, where precisely these properties are important, with the same mass turn out to be geometrically large in size. And due to convection, heat removal from aluminum parts can be greater than from copper parts.

Aluminum's activity works against soldering, a standard electrical and mechanical joining operation for many metals. Because the activity is such that it immediately oxidizes in air. And it is covered with an impenetrable film of corundum - Al2O3. Other aluminum compounds are also very strong, which makes the extraction of this most common metal in the earth’s crust energy-intensive: to produce 1 ton of aluminum you need to spend 17 megawatts/hours of electricity.

Only in our country this did not turn out to be an obstacle to large volumes of production and widespread use of this metal.

In addition to aluminum itself, alloys based on it are used - duralumin and silumin.

If pure aluminum is used mainly for electrical engineering, then various products are made from alloys: from silumin - cast things (meat grinders, dishes), thrust structures, from duralumin - frames, body parts, mounting profiles.

The alloys seem to work against the eternal enemy of aluminum solders - the oxide film - and they must be soldered well. However, the soldering of duralumin and silumin itself violates the valuable properties of these alloys at the joints, which makes the soldering fragile and quickly destroyed.

About aluminum soldering

Therefore, aluminum needs to be soldered as such, and products made from its alloys can be tried to be soldered, but only where special requirements for the mechanical strength of the things being soldered are not expected.

Work order

The usual soldering steps and tools apply when soldering aluminum. It’s just that aluminum is such that it is stricter when it comes to the choice of components.

Soldering aluminum at home requires:

• A powerful soldering iron (60–100 W or more) is sufficient. This is due to the heat capacity and thermal conductivity of aluminum. This metal removes heat very strongly from the soldering area.
• The use of additional materials and tools for processing the metal surface: emery, needle file; copper sulfate for tinning; iron or copper thin filings.
• The use of special fluxes that envelop the surface of the metal, preventing immediate oxidation by atmospheric oxygen or dissolving the oxide in acid.
• The use of other substances that create a film on the surface (solid oil, machine oil, solder fat, technical petroleum jelly, aspirin, stearin).
• Solder based on tin and zinc (8:2); tin with copper (99:1); tin with bismuth; POS 40; POS 60; solder for soldering aluminum.
• Mandatory pre-tinning of the metal surface.
• Thorough subsequent rinsing of the soldering areas in warm water to remove residual acid and flux.

Flux for soldering aluminum

A great variety of fluxes for soldering aluminum are sold - liquid, paste, pencil, gel: F-34a, F-59A, FTBf-A, F61A, F-63, FTKA, F-64 and others.

Flux for soldering aluminum

The surfaces to be soldered must be cleaned, treated with a file or sandpaper. After this, heat and apply an even layer of flux.

Tinning the metal surface

It is necessary, in a hot state under a layer of flux, to damage the Al2O3 layer, which, after mechanical stripping, has managed to form on the aluminum, and at the same time apply a layer of solder. Such damaging elements may be abrasive particles, or thin iron or copper filings, or crystals of copper sulfate added to the flux. They should, without waiting for the flux to dry or burn out, apply a layer of solder with a soldering iron and rub it into the surface with a tip. When carrying out work in a house or apartment, it is necessary to remember that the components of fluxes are caustic and toxic; when heated with a soldering iron, they boil and smoke. It is necessary to work in a ventilated area.

Soldering

Soldering copper and aluminum is no more difficult than soldering aluminum to copper. Both surfaces must be tinned; copper undergoes this without much resistance, you just need to clean it and rosin it before tinning. Copper and aluminum make excellent alloys, as well as soldering aluminum with tin; this does not present any other difficulties other than overcoming the oxide film.

The pre-tinned wires are twisted and soldered so that the solder seals the gaps between the wires.

Extended objects, such as pipes or tubes, tin flasks, are soldered to aluminum in exactly the same way. If a small part is soldered onto a wide surface with high heat dissipation (for example, a flask), then the soldered area can be additionally heated on a gas stove or burner.

It is possible to solder small holes according to the following rule: clean the surface, tin, cool a little, put a covering piece of tin or solder on the hole, carefully use a soldering iron or a jet of flame from a burner to achieve soldering of this place.

Final processing

So, when the answers to the questions “how to solder?”, “what to solder with?”, “what to solder?” left behind, the work is done, then before admiring the welded brainchild, you need to do the final finishing touches. At the same time, clean the soldered area from any irregularities, carefully solder off excess drops of solder, and after cooling, lightly check the soldering for strength. After soldering aluminum using materials containing chemical reagents, it is necessary to thoroughly rinse with water, wipe with a cloth lightly soaked in soda solution, and dry.

domelectrik.ru

Soldering aluminum at home - what and how to solder, fluxes, solders

Soldering aluminum, as many experts rightly believe, is a rather difficult technological process to perform. Meanwhile, this opinion can be considered correct only in relation to those situations when they try to solder aluminum products using solders and fluxes that are used to join parts made of other metals: copper, steel, etc. If a special flux is used for soldering aluminum , as well as the corresponding solder, then this technological process does not present any particular difficulties.

Soldering aluminum using a propane torch

Process Features

The difficulties encountered in soldering aluminum using traditional solders and fluxes are explained by a number of factors, mainly related to the characteristics of the metal. The main one of these factors is the presence of an oxide film on the surface of aluminum parts, which is characterized by a high melting point and exceptional chemical resistance. When soldering, such a film prevents the connection of the base metal and the solder material.

Before soldering aluminum products, their surfaces must be thoroughly cleaned of the oxide film, for which you can use mechanical processing or use fluxes that contain potent components.

Duralumin parts prepared for soldering

Aluminum itself, unlike the oxide film on its surface, has a fairly low melting point: 660 degrees, which also complicates the soldering process. This characteristic of aluminum leads to the fact that when heated, parts made from it quickly lose strength, and at a certain temperature, in the range of 250–300 degrees, structures made from this metal begin to lose stability. The most fusible component, which is part of the most common aluminum alloys, begins to melt already in the temperature range of 500–640 degrees, which can lead to overheating and even melting of the parts themselves.

The basis of most low-melting solders used for soldering is tin, cadmium, bismuth and indium. Aluminum does not bond well with these elements, which makes solder joints made using them very weak and unreliable. Aluminum and zinc have good mutual solubility, so this element, when used in solders, provides the resulting joint with high strength.

Characteristics of fluxes for soft soldering

Composition of fluxes used for soldering aluminum

Materials used

When soldering aluminum products, you can use solders of the tin-lead group if you thoroughly clean the surface of the parts and use highly active fluxes. The compounds obtained with their help, due to the poor mutual solubility of aluminum, tin and lead, are characterized by low reliability, and they are also prone to the development of corrosion processes. To make such compounds more resistant to corrosion, they must be coated with special compounds.

The highest quality, reliable and corrosion-resistant solder joint allows us to obtain solders containing zinc, copper, silicon and aluminum.

Solders containing these elements are produced by both domestic and foreign companies. The most common domestic brands are TsOP40, which contains 40% zinc and 60% tin, and 34A, which contains aluminum (66%), copper (28%) and silicon (6%). The zinc contained in the solder for soldering aluminum products determines not only the strength of the resulting joint, but also its corrosion resistance.

Tin-lead solders have the lowest melting point of all of the above. The highest temperatures are those that contain aluminum and silicon, as well as materials containing aluminum along with copper and silicon. The latter, in particular, includes the popular brand 34A solder, the melting point of which is in the range of 530–550 degrees.

For information: materials based on aluminum and silicon melt at a temperature of 590–600 degrees.

Taking into account the melting point, such solders are used in cases where it is necessary to connect large-sized aluminum parts that provide good heat dissipation, or products made of aluminum alloys that melt at fairly high temperatures.

But, of course, low-temperature solders demonstrate maximum ease of use, one of the most common brands of which is HTS-2000.

Solder HTS-200 for soldering parts made of aluminum and non-ferrous metals

The technology for soldering aluminum necessarily involves the use of a special flux, which is necessary in order to improve the adhesion of the base metal to the solder material. That is why it is necessary to approach the choice of such material very responsibly. This requirement is especially relevant in cases where aluminum parts need to be soldered using tin-lead solder. The composition of fluxes contains elements that form its activity towards aluminum. These elements include: triethanolamine, zinc fluoroborate, ammonium fluoroborate, etc.

Flux F-64 for soldering light alloys without preliminary mechanical surface treatment

One of the most popular domestic materials is flux brand F64. The popularity of F64 is due to the fact that this material is characterized by increased activity. Thanks to this quality, it is possible to perform soldering with F64 flux without even cleaning the surface of aluminum parts from the refractory oxide film.

Among the popular high-temperature fluxes, we should highlight the 34A material, which contains 50% potassium chloride, 32% lithium chloride, 10% sodium fluoride and 8% zinc chloride.

Preparing parts

To obtain a high-quality and reliable connection, it is not enough just to know how to solder aluminum; it is also important to properly prepare the surfaces of the parts to be joined for soldering. This preparation consists of degreasing surfaces and removing the oxide film from them.

For degreasing, traditional means are used: acetone, gasoline or any suitable solvent.

Removing the oxide film before soldering, which is also easy to do with your own hands, is mainly done using mechanical processing, for which you can use a grinder, sandpaper, a metal brush or a stainless wire mesh. Much less commonly used is a chemical method for removing such a film, which involves etching the surface of aluminum parts using acid solutions.

Cleaning surfaces before soldering using a grinder attachment

As is known, an oxide film on the surface of aluminum forms almost instantly upon its contact with ambient air. This process also occurs on a surface that has been cleaned before soldering, but the point of cleaning is that the newly formed film is much thinner than the removed one, so it will be much easier for the flux to deal with it.

Heating sources

A gas burner running on propane or butane is predominantly used as an element used to heat the dimensional aluminum parts being connected and melt the solder. If you decide to solder aluminum products with your own hands in a home workshop, then you can use a regular blowtorch.

Easy to use gas blowtorch

When heating, you must be very careful to ensure that the parts being connected do not melt. For this purpose, the surface of the parts is touched with solder as often as possible in order to control the beginning of its melting. This will indicate that the operating temperature has been reached.

When heating parts and solder before starting soldering, it is also necessary to monitor the flame of the gas burner: the mixture of gas and oxygen that forms it must be balanced. This must be done for the reason that a balanced gas mixture actively heats the metal, but does not have a serious oxidizing effect. The fact that the gas mixture is balanced is indicated by the bright blue color of the flame, which is small in size. If the burner flame is too small in size and has a pale blue color, then this is evidence that there is too much oxygen in the gas mixture.

For soldering small aluminum products, electric soldering irons and solders that melt at a low temperature are used.

Soldering techniques

Soldering parts made of aluminum, in terms of execution technology, is practically no different from the process of joining products made of other metals. First, the parts to be joined are degreased and thoroughly cleaned, after which they are placed in the desired position relative to each other. Then it is necessary to apply flux to the area of ​​the future connection and begin heating it together with the solder to operating temperature.

Soldering process of aluminum alloy parts

When the operating temperature is reached, the tip of the solder will begin to melt, so they need to constantly touch the surface of the parts, controlling the heating process.

Soldering aluminum products, for which flux-free solder is used, has its own characteristics. They consist in the fact that in order for the penetration of solder to the surface of the part not to be hampered by the oxide film, its tip must be made in striking movements at the site of the future connection. In this way, the integrity of the film is disrupted, and the solder seamlessly connects to the base metal.

You can see how soldering is done practically in the training video.

There is another technological technique that allows you to destroy the oxide film during the soldering process. This can be done using a stainless steel rod or a metal brush, which is passed over the joint and the already molten solder.

To obtain the most durable connection using the soldering method, the surfaces to be joined must be pre-tinned.

Scope of the process

Not only soldering aluminum at home is of great practical importance. This technology is also actively used at repair and production enterprises. Using the soldering method, it is possible to obtain connections that are characterized by high strength, reliability and aesthetic appeal.

When working with thin sheet aluminum, soldering avoids deformation of the material

This technology is very popular when performing repair work on vehicles, tractors and motorcycles. This popularity is explained by the fact that when soldering there is no change in the structure of the metal being joined, therefore this method of connection in many cases is even more preferable than welding.

There is practically no alternative to soldering when it is necessary to restore the tightness of an aluminum radiator or crankcase, or to repair a worn or damaged part made of an aluminum alloy. It is also convenient that you can do such repairs yourself; this does not require complex and expensive equipment.

Home repaired car radiator

Burnouts, chips and cracks formed in a cylinder block made of aluminum alloy can also be successfully repaired by soldering. This technology is very useful if it is necessary to restore worn internal threads. In this process, the worn threaded hole is filled with molten solder and then a bolt is screwed into it. After the solder has hardened, the bolt is turned out of the hole, and inside it is a thread formed according to the required parameters. This simple operation allows you to obtain a new thread, which in its strength characteristics is in no way inferior to the original one.

In addition, soldering is successfully used to repair and restore the tightness of pipes made of aluminum and alloys of this metal. Such pipes are now actively used in many technical devices. With the help of soldering, you can do it yourself, without resorting to the expensive services of qualified specialists, to repair many objects made of aluminum and its alloys used in everyday life: dishes, stairs, various interior parts, gutters, siding elements, etc. With the help of soldering you can not not only to repair, but also to make any aluminum structures with your own hands.

The use of high-quality consumables and strict adherence to technology, which is quite easy to learn using video lessons, allows you to obtain connections using soldering that are of high quality, reliability, attractive and neat appearance.

Using improvised means

There are often situations when there is no active flux and solder on hand, which is specifically designed for joining aluminum parts, and they need to be soldered urgently. In such situations, soldering can be done with regular solder consisting of aluminum and tin or tin and lead. In this case, rosin can be used as a flux.

When using this soldering method, the oxide film is destroyed under a layer of rosin, to which metal filings can be additionally added. To destroy it, use a special soldering iron with a scraper, which must first be tinned. The scraper, along with sawdust, destroys the oxide film on the surface of the parts, and rosin prevents the formation of a new one. In addition, the scraper-soldering iron, moving the molten solder over the site of the future connection, ensures its tinning.

Of course, this soldering method is very troublesome and does not always guarantee a high-quality and reliable connection, so it can only be used in extreme cases. It is most advisable to spend time and money on purchasing high-quality solder and flux and not worry about the quality of the connection formed with their help.

Soldering aluminum at home is carried out by many self-taught craftsmen. Every man can find a soldering iron in his house, since he cannot do without this tool. In production, as well as at home, in order to solder aluminum, it is necessary to use special materials and devices. This type of soldering can be done using tin-lead solders 50 and 61. If you are going to carry out this type of work at home, this can be done in several ways and with different materials.

Remember that the main task is to remove the oxide film from the metal surface, and direct contact with air should not be allowed; to do this, use rosin, mineral oil or alkaline, and you can also use a saturated solution of copper sulfate.
In order to begin to consider the processes of soldering aluminum at home, you need to know some ways to prepare the material for this process.

Methods for preparing material

For the first method, rosin is used to clean the soldering area. And after that, the soldering iron is immediately connected to work, with the help of which you press the sandpaper to the place of soldering. Then you need to wipe the soldering area with sandpaper. Now it's time for the aluminum patch, which you can solder in the usual way.

Although rosin is often used in this processing method, mineral oil for a sewing machine is best.

Second cleaning method. In the place where something needs to be soldered, iron filings are additionally added to the rosin. Using this mixture, a heated soldering iron rubs the area so that the solder is as effective as possible. This effect occurs due to the fact that metal filings remove oxide from the surface, and this ensures maximum adhesion between surfaces. This method does not require additional metal cleaning.

The third cleaning method is labor-intensive and will take you a lot of time. But it is considered the most reliable. First, you need to treat the required area to remove the oxide film. Then, in the place where soldering will be carried out, it is necessary to create a plastic side, which will later serve as a bath.

You can make this bath from ordinary plasticine. It is necessary to apply a layer of copper sulfate to its bottom. Just remember that the tray is used where there is a large soldering area, and for minor damage you do not need it at all.

Now the bare copper wire is placed in this device. Its diameter is about 3 mm. Just remember that the wire should consist only of copper. The wire must be kept at a distance of one millimeter from the working surface.

To do this, use some kind of additional stand, and the wire that is in the bath must certainly create contact with the body. Then make contact with some current source, the voltage should be from 3 to 12 W.

You can do all this with the help of two connecting ends, and the power source can be a battery, a rectifier, or an ordinary battery. You need to provide all this with a light bulb, which will be responsible for the rated DC voltage.

It will light up when the aluminum surface comes into contact with a copper wire that is lowered into the bath. If the light goes off, it means the wire has touched the bottom of the bath, and if not, then the whole process is interrupted.

After this, the copper sulfate should come to a boiling state, and at this moment red copper sulfate is formed. You must wash and dry the red layer. Feel free to proceed with ordinary soldering of the surface.

Return to contents

Aluminum soldering process

Materials and tools:

• rosin;
• soldering iron;
• mineral oil;
• metal filings;
• copper sulfate;
• plasticine;
• welding pencil;
• lighter;
• piece of glass.

A welding pencil resembles a sealant solder, thanks to it you can get a strong and reliable connection of parts, wires, and aluminum tubes. Many people refuse simple gas torches, and are increasingly inclined to use a welding pencil.

But you need to take into account that the operation of different devices has its pros and cons. The operating process of this type of tool is very simple; for this you need to set fire to a pencil.

For this kind of manipulation, a simple lighter is suitable, with which you will set fire to the edge of the solder. The device will burn due to magnesium, which is included in its composition. It heats up to the temperature required to melt the aluminum.

Under the influence of high temperature, a molten mass appears. You need to apply it to your work surface. The angle of impact of the pencil does not matter, since the resulting mass adheres very well to the aluminum.

After the solder is soldered from the working surface, the pencil stops working, but the aluminum mass continues to burn. After about 20 seconds, the entire surface will be at the same temperature.

And after that, you can safely start filling the aluminum into the work surface. Use a pencil or a piece of glass for this purpose.