How to solder aluminum with a soldering iron at home

Soldering aluminum at home with a soldering iron and gas torch: solder and flux

Soldering aluminum is a rather difficult task. Basically, soldering aluminum parts becomes more difficult due to the appearance of a chemically resistant oxide on the metal surface.

In addition, due to the relatively low melting point and low temperature of loss of strength, it is quite difficult to heat aluminum without causing destruction of the entire product. Therefore, soldering aluminum parts is difficult if conventional consumables are used.

At the moment, soldering of aluminum products is carried out using specialized fluxes and solders.

Process Features

The key problems of soldering aluminum with traditional solders and fluxes are related to:

• the formation of an oxide film with a high melting point and good chemical resistance, preventing interaction with tin or lead solders;
• low melting point of pure metal, making high-quality soldering difficult.

To solder aluminum parts, specialists must clean the surface of the material from the oxide film or use specialized aggressive solders and fluxes.

Soldering aluminum with a soldering iron should be done using zinc solders. This option for low-temperature soldering of aluminum, unlike cadmium, bismuth, tin or indium, interacts well with pure metal and forms a strong seam.

Melting temperature of aluminum products for soldering.

The basic rules for soldering aluminum at home in the absence of zinc or aluminum solder include the following points:

1. Pre-cleaning of the surface.
   The area where soldering work needs to be performed should be carefully cleaned of paint, dirt and particles of other metals.
2. Grinding.
   For better adhesion between the solder and aluminum, the area of ​​the intended connection should be sanded.
3. You should not take a long break between cleaning aluminum and directly applying flux.
   Due to the high rate of oxide formation on the surface, the cleaning process for aluminum may need to be repeated.
4. The correct choice of device for heating the soldering area.
   Electric soldering irons with adjustable tip temperatures are ideal for this work.
5. Monitoring the temperature of the connection point.
   Due to the good thermal conductivity of the metal, the temperature will quickly spread over the entire area of ​​the product, and therefore the soldered area will quickly cool down.
6. A prerequisite for successful soldering of aluminum is tinning the area of ​​the intended contact.
   If a drop of solder is applied to the cleaned area of ​​aluminum in time, an oxide film will not be able to form.

There are several secrets that can be used to solder aluminum without specialized solder:

1. Destruction of the oxide film by intense friction of the joint with a brick.
   After a certain amount of dust has peeled off the stone, you should put the required amount of rosin or flux on the soldering iron tip and fill the soldering area. After this, you should make strong pressure movements with the flat cut of the soldering iron at the place of the planned soldering. With this simple action, brick dust will destroy the thin oxide film, and the solder on the soldering iron will tin the cleaned metal.
2. Destruction of the oxide film using iron particles.
   To do this, grind off a thick nail with a file, apply a large amount of liquid rosin or flux to the soldering area, and then add metal filings. After the soldering agent has hardened, you should put solder on the tip of the soldering iron and press it firmly into the soldering area.
3. Use of transformer oil.
   To implement this method, remove the top layer of the part with sandpaper, and then pour oil onto the cleaned area. After this, you can rub in the heated solder and get good adhesion between the tin and aluminum.

Necessary materials and available tools

Soldering of aluminum products with proper surface preparation can be performed with all types of solders. For example, soldering aluminum with tin is possible by removing the oxide film.

Materials required for soldering aluminum.

However, in most cases, aluminum joints obtained by soldering with tin solder have low reliability due to the poor solubility of the materials.

The most optimal solders for soldering aluminum are:

• zinc;
• copper;
• silicic;
• aluminum.

There are a large number of solders on the market based on the above materials. One of the most common zinc solders is TsOP40, which contains 40% zinc and 60% tin. In addition, 34A solder remains popular, consisting of 66% aluminum, 28% copper and 6% silicon.

Special mention should be made of special solder for low-temperature soldering of aluminum parts. One of the most common consumables for such an operation is HTS-200 solder.

Of course, we should not forget about the mandatory use of a special flux for low-temperature soldering of aluminum.

The flux for trouble-free soldering of aluminum must contain at least one of the following elements:

• triethanolamine;
• zinc fluoroborate;
• ammonium fluoroborate.

One of the brands of fluxes for welding aluminum with a gas torch is F64. The popularity of this flux is due to its high activity. Even aluminum parts can be soldered with F64 flux without first stripping the oxide film.

The F64 flux composition includes:

• 50% potassium chloride;
• 32% lithium chloride;
• 10% sodium fluoride;
• 8% zinc chloride.

Preparing parts

Soldering aluminum at home involves careful preparation of the part.

As a rule, qualified craftsmen perform the following procedures before soldering aluminum with their own hands:

1. Degreasing the surface.
   The most suitable substances for high-quality degreasing of the soldering area are acetone, gasoline and solvent.
2. Removing the oxide film.
   This procedure is carried out using a grinding machine or a homemade wire sponge. In rare cases, specialists use film etching using chemicals, such as acid.

After completing all the preparatory procedures, you can proceed to direct soldering of aluminum at home.

Technological approaches for aluminum soldering

The technology for soldering aluminum with flux is practically no different from joining other metals.

The entire process of soldering aluminum with solder can be divided into the following stages:

1. Surface preparation.
   Before soldering aluminum, the parts to be joined should be cleaned and degreased.
2. Installing the product into working position.
   This step may require a vice or a third hand.
3. Applying flux to the soldering area.
4. Warming up the product using an electric soldering iron or gas torch.
5. Apply solder or solder paste to the required areas.
   Zinc or copper solders are suitable for this role. Sometimes high-temperature solders may be needed to ensure good mechanical fixation of the product.

Scheme for soldering aluminum pipes.

It is important to remember that when soldering with flux-free solder, you should make striking movements with the soldering iron in order to ensure interaction between the components of the solder and the metal.

Carrying out work using a special soldering iron with a scraper will give good results in the following cases:

• soldering of aluminum utensils;
• soldering aluminum wires;
• seal surfaces not subject to strong mechanical loads;
• connection of small parts.

Soldering of massive aluminum parts and thick rods should be carried out using welding or a torch. Welding is not always suitable due to the high temperature of the arc, which melts the metal. Therefore, most specialists prefer to use burners.

The best effect is achieved with continuous soldering with a torch. If, for some reason, the soldering process had to be stopped, the entire seam should be completely heated in order to ensure uniform distribution of the solder and get rid of unsoldered areas.

The process of soldering aluminum rods using a torch is divided into the following stages:

1. Cleaning metal from dirt and preparing the surface by grinding.
2. Heating the entire surface of massive products using a burner.
3. Remove all flammable materials from the work area.
4. Turn on the hood to neutralize the caustic fumes of solder.
5. Preparation of solder wire.
6. Preparation of flux grades F-59A, F-61A or F-64A.

It is allowed to heat the metal to a bright orange color. In this form, the metal does not melt, and the solder is applied as evenly as possible.

The most complex and at the same time high-quality method of joining aluminum products is welding. This method is difficult due to the low melting point of the metal.

Qualified specialists most often weld aluminum products using the following methods:

• welding using coated electrodes;
• welding using shielding gas.

The first welding option has the following disadvantages:

• low weld strength;
• strong splashing of metal during cooking;
• poor separation of slag from the seam.

Welding in an inert gas atmosphere has no noticeable disadvantages and is considered the best method for joining aluminum parts.

Heating an aluminum product

The heating method for aluminum parts is selected individually. Products of relatively small sizes can be heated with an electric soldering iron and tinned with solder and flux for soldering copper. For more massive parts, it makes sense to use another method of soldering aluminum using a gas torch or blowtorch.

Table of solder brands for aluminum soldering.

When warming up the part, you should:

1. Control the temperature of the heated product.
   You can find out the current surface temperature of a part by touching it with a solder rod. When the aluminum solder wire begins to melt, reduce the heat and begin direct soldering using active flux.
2. Watch the burner flame.
   The burner jet contains a mixture of natural gas and oxygen, and therefore should be bright blue. The correct composition of the burner flame allows the aluminum part to oxidize less and not overheat.

The key advantages of heating massive aluminum products with a gas burner are presented:

1. Low cost of equipment.
   A gas burner consumes a small amount of fuel and is sold at any hardware store.
2. Absence of uneven heating and stress inside the product.
   Parts heated by a gas burner have an even seam and do not change geometry due to overheating.
3. Easy control of operating temperatures.
   If the metal heats up too much, reduce the intensity of the burner flame.
4. Possibility of soldering work at home.
   When the metal is heated with a burner, there is no pungent odor, there is no ultraviolet irradiation of the skin and no sparks fly.

Conclusion

Soldering aluminum with flux is a rather non-trivial task. When connecting aluminum products, certain standards must be observed, and the surface of the part must meet numerous requirements. If the technological process is not followed, the welded or soldered seam will crack and fall apart.

Aluminum welding technology depends on the massiveness of the product. Small parts, such as wires or dishes, can be easily repaired with an electric soldering iron, but large rods or pipes should be heated with a gas torch or blowtorch.

Source: https://tutsvarka.ru/vidy/pajka-alyuminiya

Soldering aluminum at home: instructions

There is a widespread belief that it is impossible to solder or tin aluminum (as well as alloys based on it) without special equipment for this.

Two factors are cited as an argument:

1. upon contact with air, a chemically resistant and refractory oxide film (AL2O3) is formed on the surface of the aluminum part, resulting in an obstacle to the tinning process;
2. The soldering process is significantly complicated by the fact that aluminum melts at a temperature of 660°C (for alloys this ranges from 500 to 640°C). In addition, the metal loses strength when, during the heating process, its temperature rises to 300°C (for alloys up to 250°C), which can cause a violation of the stability of aluminum structures.

Considering the above factors, it is truly impossible to solder aluminum using conventional means. The use of strong fluxes in combination with the use of special solders will help solve the problem. Let us consider these materials in detail.

Solder

Commonly used low-melting solder bases are tin (Sn), lead (Pb), cadmium (Cd), bismuth (Bi) and zinc (Zn). The problem is that aluminum is practically insoluble in these metals (with the exception of zinc), which makes the connection unreliable.

By using a flux with high activity and properly treating the joints, you can use tin-lead solder, but it is better to avoid such a solution. Moreover, a solder joint based on the Sn-Pb system has low corrosion resistance. Applying a paint coating to the soldering area allows you to get rid of this drawback.

For soldering aluminum parts, it is advisable to use solder based on silicon, copper, aluminum, silver or zinc. For example 34A, which consists of aluminum (66%), copper (28%) and silicon (6%), or the more common TsOP-40 (Sn - 60%, Zn - 40%).

Domestic solder – TsOP-40

Note that the higher the percentage of zinc in the solder, the stronger the connection and the higher its resistance to corrosion.

High-temperature solder is considered to be solder consisting of metals such as copper, silicon and aluminum. For example, like the above-mentioned domestic solder 34A, or its foreign analogue “Aluminium-13”, which contains 87% aluminum and 13% silicon, which allows soldering at temperatures from 590 to 600°C.

"Aluminum-13" produced by Chemet

Flux

When choosing a flux, it is necessary to take into account that not all of them can be active towards aluminum. We can recommend using products from a domestic manufacturer for such purposes - F-59A, F-61A, F-64, they consist of ammonium fluoroborates with the addition of triethanolamine. As a rule, the bottle is marked “for aluminum” or “for aluminum soldering.”

Domestic flux

For high-temperature soldering, you should purchase flux produced under the brand 34A. It consists of potassium chloride (50%), lithium chloride (32%), sodium fluoride (10%) and zinc chloride (8%). This composition is most optimal if high-temperature soldering is performed.

Recommended flux for packing at high temperatures

Surface preparation

Before you begin tinning, you must complete the following steps:

• degrease the surface using acetone, gasoline or any other solvent;
• remove the oxide film from the place where soldering will be performed. For cleaning, use sandpaper, an abrasive wheel or a brush with steel wire bristles. As an alternative, etching can be used, but this procedure is not so common due to its specificity.

It should be taken into account that it will not be possible to completely remove the oxide film, since a new formation will immediately appear in the cleaned area. Therefore, stripping is carried out not with the goal of completely removing the film, but to reduce its thickness in order to simplify the task of the flux.

Heating the soldering area

To solder small parts, you can use a soldering iron with a power of at least 100W. Massive items will require a more powerful heating tool.

Soldering iron 300 Watt

The best option for heating is to use a gas burner or blowtorch.

Simple gas burner

When using a burner as a heating tool, the following nuances should be taken into account:

• Do not overheat the base metal, as it may melt. Therefore, it is necessary to regularly monitor the temperature during the process. This can be done by touching the solder to the heated element. Melting the solder will let you know that the required temperature has been reached;
• Oxygen should not be used to enrich the gas mixture, since it promotes strong oxidation of the metal surface.

Soldering instructions

The process of soldering aluminum parts does not have its own distinctive features; it is carried out in the same way as with steel or copper.

The algorithm of actions is as follows:

• the soldering area is degreased and cleaned;
• the parts are fixed in the desired position;
• the connection area heats up;
• touch the solder rod (containing active flux) to the joint. If flux-free solder is used, then flux is applied to destroy the oxide film, after which a solid piece of solder is rubbed over the soldering area.

A brush with steel wire bristles is also used to break down the aluminum oxide film. This simple tool is used to rub molten solder over an aluminum surface.

Soldering aluminum - complete video instructions

Source: https://www.asutpp.ru/pajka-alyuminiya.html

How to solder aluminum with tin?

Soldering aluminum with standard solder using conventional technology is unreliable and impossible. The tin on it rolls into a ball, not wanting to stick, and if it does stick, the result is a weak connection that breaks under the slightest load. To prevent this from happening, you need to solder in a special way, and then even ordinary solder will hold tight.

Inventors shop at a budget Chinese online store.

• solder 60/40;
• mineral oil or petroleum jelly;
• alcohol.

How to solder aluminum correctly

An oxide film instantly forms on the surface of the aluminum, which prevents adhesion between the base and the solder. To prevent it from interfering, you need to create an airless environment at the soldering site. To do this, apply a thin layer of Vaseline to the area of ​​aluminum that has been cleaned of dirt. You can use mineral or other automotive oil instead.

DIY electronics in a Chinese store.

If Vaseline was used, then you need to apply a soldering iron tip to it so that it melts into liquid oil. After this, take a mounting knife or other sharp object and use it to scratch the aluminum under the Vaseline.

It is important that the scratches are made on a surface that is sealed from air. As soon as the Vaseline begins to thicken, it should be melted again with a soldering iron tip.

You need to actively rub with a knife blade to remove the oxide film on the metal, and in addition to create a relief to which the solder will then stick well.

After removing the oxide film, the oil is not erased. A soldering iron tip is applied to the soldering site, and the aluminum is heated to operating temperature. Then the required amount of solder is deposited. It will sit right in the oil.

A drop of solder is lightly rubbed over the prepared surface. You need to press it into the resulting scratches. The solder will push the oil to the sides so it won't interfere with adhesion. The absence of an oxide film will allow the tin to stick to the aluminum, rather than forming into a ball that easily falls off.

Then, tinned wires, wire, or whatever is needed can be applied to the surface prepared with oil and friction. They will be soldered in a second, without taking all the tin from the aluminum, as usually happens. After soldering, the remaining oil is removed with a cotton swab soaked in alcohol.

This method allows you to achieve the same soldering reliability as when connecting two copper elements. Moreover, unlike another common method with oil, when the oxide film is removed by five minutes of friction with a hot soldering iron tip, tearing it off with a knife is faster.

Watch the video



Source: https://izobreteniya.net/kak-payat-alyuminij-olovom/

Rod for soldering aluminum at home / Tools / iXBT Live

Hi all! Many people know that aluminum is soldered mainly in an argon atmosphere with a special welding machine, but there is also an option for working with a gas torch, and even a turbo lighter can be used on a small scale.

In general, this is not my first acquaintance with this wire, but the shopping experience is not very good, so I will share not only the test result, but also trusted places to buy so as not to get sample No. 2 , but let’s start in order.

• Characteristics
• Unboxing and appearance
• Testing
• Results

Characteristics

Diameter: 2.0 mm
Length: 500 mm
Soft solder ISO 3677: ~B-Zn98Al 381-400
Approximate composition (weight%): 2.4 Al – rest Zn
Melting point ºС: 360
Tensile strength (MPa): Up to 100 (Al)
Density (g/cm3): 7.0

Unboxing and appearance

The last and most profitable purchase was sample No. 3 from banggood.

Came in a small gray package

The rod is additionally packaged in a transparent zip bag.

5 meters cost me $8 with points, that is $1.6 per meter - go to the store

White powdery flux is visible in the center, the rod is moderately hard, looks like aluminum without oxidation

Comparison

The first one I bought was the leftmost sample No. 1 from Ali. Its properties are absolutely identical to sample No. 3 , but 3 meters cost me $12 , that is, $4 per meter , which is almost three times more expensive. check current price

In the center is sample No. 2 . It costs $5 for 3 meters or $1.7 per meter , like sample No. 3

But as soon as you take the bag in your hand, you realize that this is a POS with not very thick flux inside.

don't buy here

Two more samples at $8 for 3 meters were never delivered, they were probably not even sent.

Testing

Over time, aluminum becomes covered with an oxide film, due to which the surface becomes dull, so, before soldering, the surfaces must be cleaned to a shine, otherwise the solder will simply roll off in balls on the surface, regardless of the degree of its heating. Sample No. 1

 In general, it is correct to heat the part to a temperature of about 400 degrees, and then simply move the rod, which will melt and fill the cracks, but I have little experience, so in order not to overheat the surface, I periodically bring the rod into the burner flame. If the temperature is low, the solder will roll down the surface like a ball; if it is sufficiently high, it will tin it.

 The fracture test shows a good result - the break does not occur along the seam

Sample No. 2 . It melts very well, emits a lot of smoke, and smells like burnt “aspirin.” It sticks to aluminum, but if you overheat it, it burns out pretty quickly.

It is inconvenient to work due to the stench and the need to control the temperature.

Sample No. 3 . I decided to solder the tubes with the outer walls

We try to break the seam. After the tube came out of the vice, I clamped it higher, bringing it out of focus and only noticed this at the stage of creating GIFs

But there is a photo of the result which shows that the seam was not damaged.

And finally, let’s splice the aluminum tube with a piece of duralumin.

 The tear test was also successful.

Results

An interesting wire - aluminum solders perfectly, filling even small gaps, the main thing is that the joints are not dirty. It also sticks well to copper, but experienced people say that it is better to use other alloys to work with it, although this rod is quite suitable for emergency field repairs.

The melting point of aluminum is about 660ºC, it would seem that you can use rods at 450-500 degrees, but you may encounter two problems:
1. A massive part needs to be heated up to 500 degrees with something else
2. You can overheat the soldering area and ruin the part

Sample No. 3 seemed to me the most optimal .
It corresponds to the declared characteristics and costs at least half as much as the others. There are also lots of different lengths to choose from: 1 meter - $2.89
2 meters - $4.39
3 meters - $6.39
5 meters - $9.89

go to the store

Source: https://www.ixbt.com/live/instruments/prutok-dlya-payki-alyuminiya-v-domashnih-usloviyah.html

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.

Source: http://electricavdome.ru/kak-payat-alyuminij-olovom-svoimi-rukami.html

Soldering aluminum

Industrial production of aluminum, by historical standards, began relatively recently. But during this time, this material has firmly entered our lives.

Its main parameters - high electrical and thermal conductivity, low weight, resistance to corrosion - have led to the fact that this metal has become the main material used in the aviation and space industries.

In addition, it is impossible to imagine the streets of our cities without aluminum; translucent structures (doors, windows, stained glass), advertising structures and much more are made from it.

Soldering aluminum

When processing it, it is permissible to use almost all types of processing - turning, stamping, casting, welding and soldering. The latest methods are used to produce permanent connections from aluminum blanks.

General principles of soldering aluminum at home

Many people sincerely believe that soldering aluminum at home is a rather complicated process. But in fact, everything is not so bad. If you use the appropriate solders and fluxes, then there should not be any particular difficulties. If a home craftsman solders aluminum parts using materials intended for copper or steel, the result will most likely be negative.

Soldering tools

Use of transformer oil

As noted above, the main obstacle when performing soldering is the presence of an oxide film. Before soldering aluminum it must be eliminated. To remove it, different methods are used, ranging from the use of an abrasive tool to special fluxes. In addition, there are “folk” methods. One of them is related to the use of transformer oil.

Transformer oil

To remove the oxide film, the following composition is used: transformer oil is added to the abrasive powder. With constant stirring, the result should be a paste-like mass. It must be applied to a previously cleaned soldering area. After this, the soldering iron tip must be thoroughly tinned and the prepared areas must be rubbed until tin appears. After this, the soldering areas must be washed and work can continue.

What kind of solder is used for soldering aluminum?

Most solders contain substances that do not dissolve in aluminum. That is why, to create permanent connections of aluminum parts, so-called refractory solders are used, made on the basis of aluminum, cadmium, zinc and some other substances.

Low-melting solders are also used for soldering aluminum.

Their use allows you to perform work at low temperatures. This allows connections to be created without changing the properties of the aluminum. But it should immediately be noted that the use of such materials cannot ensure the proper degree of corrosion resistance and strength of the joint.

Solder for soldering

Optimal soldering results can be obtained by using a composition that contains aluminum, copper, and zinc. Work with such solders must be performed with a soldering iron, the tip of which is heated to 350 °C. When connecting parts, you need to use flux, which consists of a mixture of oleic acid and lithium iodide.

The composition for joining aluminum parts can be prepared at home, or you can simply purchase it in a store.

One of the commercially available solders for aluminum is HTS-2000. Soldering can be done with this solder without using flux. The great thing about this compound is that it can penetrate the oxide film and can create strong molecular bonds. The service life of connections made using this alloy is 10 years.

How to solder correctly using a torch

The need for soldering aluminum and its alloys may arise both in industrial and domestic conditions. This process can be used when performing repairs on parts, but sometimes you have to deal with more extensive work.

Processing aluminum is associated with a number of difficulties and therefore traditional soldering technology materials do not always guarantee the proper result.

One of the frequently used methods for obtaining permanent connections is directly related to the use of a gas burner.

Working with aluminum means that the oxide film that is on the surface of the part prevents the parts from joining.

Soldering with a torch is significantly different from working with a soldering iron and is rightfully considered more practical. While working with the burner, the master can adjust the temperature. And this provides additional opportunities for surface treatment of workpieces. In this case, the thickness of the material does not play a special role. Sometimes when working with a burner, fluxes and additional surface treatment agents are used.

Soldering aluminum using a gas torch

Soldering aluminum with a gas torch in a home workshop allows you to preheat workpieces and consumables.

Undoubtedly, to obtain a high-quality connection, experience is required. The fact is that aluminum has a low melting point; therefore, consumables used in soldering have good fluidity. If the master makes a mistake, then there is a high probability that the solder will simply spread over the workpiece without ever getting into the seam.

What flux to use

Flux for soldering aluminum must be selected based on a set of factors. There is a so-called binary flux based on orthophosphoric acid. Fluxes of this class do not require additional rinsing. This material can also be used to solder other metals.

Types of fluxes for aluminum soldering

Advantages

Soldering is one of the ways to obtain permanent metal joints. But unlike other methods, until recently it was characterized by low productivity and low strength at the junction. This and a number of other reasons led to the fact that it did not receive widespread industrial use.

With the development of technology, methods for connecting parts using an electron beam and ultrasonic waves have become available. The emergence of special solders and fluxes has significantly improved the quality of solder joints.

Modern soldering technologies make it possible to use finished products without further processing on mechanical equipment. Soldering has become one of the main technological processes in mechanical engineering, aviation and space industries and, of course, electronics.

Soldering has a number of undoubted advantages compared to welding. The process of joining parts in this way takes place with significantly less heat consumption.

In other words, during this process there are no major changes in the structure of the metal. Its physical and chemical parameters remain virtually unchanged.

After soldering, phenomena such as residual deformation may occur; its dimensions are incomparable with those that remain after, for example, welding in a cloud of shielding gases.

That is why the use of soldering guarantees more accurate compliance with the dimensions specified in the technical documentation for the product. Using this method allows you to join dissimilar metals. In addition, we can say that these processes can be automated quite easily.

Flaws

When talking about soldering aluminum parts, we must always remember that to work with it it is necessary to use special solders and fluxes that are able to meet the requirements for the quality of the resulting joints.

The slightest violation of technology or the use of unsuitable materials will lead to the fact that the resulting seam will not meet quality requirements.

Source: https://stankiexpert.ru/spravochnik/svarka/pajka-aluminiya.html

How to solder aluminum at home, features of aluminum soldering

Soldering aluminum is a difficult process to do at home. The complexity is explained by the properties of the metal, which make it difficult to connect individual aluminum parts with other substances. Aluminum must be joined in compliance with specially developed technologies that ensure the quality of soldering. What matters is the experience of the craftsman who joins aluminum parts by soldering.

Why is aluminum difficult to solder?

Many people have tried to solder aluminum at home and understand well: the solder does not want to stick to the surface of the parts. This occurs due to the formation of a stable oxide film on the metal, which has low adhesion to the solder material. Methods for soldering aluminum at home come down to fighting the protective film.

In mineralogy, aluminum oxide is called corundum. It consists of transparent crystals, which are gemstones. Corundum has different colors depending on the impurities: chromium gives a reddish tint, sapphire gives a bluish tint. The oxide film is highly durable and cannot be soldered. It must be removed from the surface and then begin to solder the parts.

How to remove oxide film

The film is removed from the metal surface in several ways, the most effective being chemical and mechanical. Both methods require an airless environment in which there is no oxygen to work.

The chemical method is based on the deposition of zinc or copper on the surface of the workpiece by electrolysis. Copper sulfate in the form of a concentrated solution is applied to the area prepared for soldering.

The negative terminal of a battery or other power source is attached to a clean area of ​​metal. One end of the copper wire is connected to the positive terminal, the other is dipped into a solution on the surface of the aluminum.

As a result of electrolysis, copper or zinc is deposited in a thin layer on the aluminum and adheres tightly to it. Now you can solder aluminum with tin.

An oil film is used to remove the oxide. For this method, it is better to use synthetic or transformer oil with a low water content. Other types of oils need to be kept at a temperature of +150+200°C, the water will evaporate. At higher temperatures, the contents will begin to splatter. Dehydrated oil is applied to the surface of the aluminum part. Use sandpaper to rub the aluminum under the applied layer to remove the oxide.

The emery cloth is replaced with a scalpel, a serrated soldering iron tip, or iron filings obtained from a nail rubbed with a file. The shavings are poured onto the oil and the soldering iron tip is rubbed over the surface, removing the oxide layer. It is advisable to heat a massive part with a hot air stream. The solder is dipped into the oil droplet with a soldering iron and rubbed over the soldering area. To improve the soldering process, rosin or other flux is added.

For soldering aluminum wires, fluxes based on acetylsalicylic or orthophosphoric acid, boric or sodium salts have been created. Rosin is rarely used; it is ineffective in the case of aluminum. Fluxes are used when soldering wires, pots and other things.

Fluxes for aluminum soldering

Fluxes are highly active, so after soldering they need to be washed off with a solution of water and alkali. Baking soda works well as an alkali. After the alkali, the joint is washed with clean water. Respiratory organs should be protected from flux vapors entering them. They can irritate mucous membranes and enter the blood. The most common of them need to be considered each separately.

Rosin

Rosin is the most popular of all fluxes. It is used in joining various metals. It works on aluminum only in the absence of air, so it is rarely used. More time is spent when working with rosin, but less efficiency. This flux is not for professionals; it can perform soldering, but the quality of the connection is not strong.

Powder flux

Aluminum is soldered with a gas torch using powder fluxes. It is not recommended to add oxygen to the flame; it reduces the efficiency of the flux. The most common fluxes:

• F-34A;
• borax;
• acetylsalicylic acid;
• solder fat.

F-34A is an active flux containing 50% potassium chloride, 32% lithium chloride, 10% sodium fluoride and 8% zinc chloride. The composition is used with solders containing chemical additives. It is hygroscopic and dissolves in water.

Borax is a powder that melts at 700°C, is soluble in water, and can be washed off with an aqueous solution of citric acid. It is characterized by low cost.

Acetylsalicylic acid is found in the form of aspirin tablets. When heated by a soldering iron, vapors that are harmful to human health are released, burning the nose, eyes and respiratory organs.

Solder fat consists of paraffin, ammonium and zinc chloride, and deionized water. Solders well preheated areas that have undergone tinning procedure. After soldering aluminum parts, it is recommended to wash off the remaining flux, otherwise it will cause corrosion of the metal.

Liquid flux

Liquid flux is applied to the soldering area in a thin layer. When working with a soldering iron, it evaporates quickly, releasing scalding fumes. Flux F-64 contains fluorides, tetraethylammonium, corrosion inhibitors and ionized water. It destroys the oxide film well and helps to solder large aluminum workpieces. Used for soldering copper, aluminum, galvanized iron and other metals.

F-61 consists of triethanolamine, ammonium fluoroborate and zinc fluoroborate. Used for tinning and soldering aluminum alloys at temperatures up to 250°C. Castolin Alutin 51 L consists of cadmium, lead and 32% tin. Works most effectively at temperatures above 160°C.

Any of the listed fluxes helps to solder an aluminum pan, aluminum blanks of different sizes, and connect duralumin and duralumin (duralumin) blanks by soldering.

Source: https://odinelectric.ru/knowledgebase/kak-spayat-alyuminij-v-domashnih-usloviyah

How to solder aluminum at home: solder for soldering, methods, features

The procedure for soldering aluminum elements at home is a very problematic process, which is facilitated by the use of special materials.

The work is complicated by the immediate appearance of a thin oxide film at the stripping site, which interferes with soldering. An additional difficulty is created by the material itself, which has a low melting point (+660 °C).

Using solder for soldering aluminum, special strong fluxes and following technology, you can independently solder almost any aluminum object.

Features and principles of soldering

The low temperature value of metal melting complicates the technological process of soldering, as well as repairing products with your own hands.

Parts very quickly lose strength when heated, and structures reduce stability when the temperature reaches 300 degrees.

Low-melting solders consisting of bismuth, cadmium, indium, and tin come into difficult contact with aluminum and do not provide sufficient strength. Excellent solubility is observed in the metal in combination with zinc, which makes the soldered areas highly reliable.

Before soldering begins, aluminum elements are well cleaned of oxides and dirt. To do this, you can use mechanical force with brushes or use special fluxes made from a potent composition. Before the procedure itself, be sure to tin the areas to be treated.

The tin coating will protect the part from the formation of oxides. In order to reliably solder aluminum products, it is necessary to choose the right heating tool, taking into account the volume of metal being processed.

In addition, the reliability of the connection depends on the alloy chosen, as well as the flux for soldering aluminum.

Soldering methods

Soldering of aluminum products is carried out with an electric soldering iron, a blowtorch or a gas torch. There are three ways to solder various aluminum objects:

• with rosin;
• using solders;
• electrochemical method.

With rosin

This option for soldering aluminum objects, wires, cables is used for small parts. To do this, the cleaned section of the electrical wire is covered with rosin and placed on a piece of sandpaper with a medium grain size. The wire is pressed from above with the tinned tip of a heated soldering iron. This action is carried out several times, after which the procedure of soldering the electrical wires itself is performed. You can use a rosin solution in diethyl ether.

In this case, the end of the soldering iron is not removed from the end being tinned, but rosin is added on top. An electric soldering iron with a power of about 50 W is suitable for twisting thin aluminum wires. With an aluminum thickness of about 1 mm, a 100 W soldering iron is required, and parts larger than 2 mm require preheating of the joint.

Using solders

This method is the most common and is used in electrical engineering, in the repair of automobile parts, as well as other products. Before soldering aluminum, the area to be soldered is pre-coated with an alloy and the tin-plated elements are subsequently connected. Pre-tinned parts are connected to each other, as well as to other alloys and metals.

Soldering of elements can be carried out using light alloy solders containing tin, zinc, and cadmium. In addition, refractory materials based on aluminum are actively used.

Why are light alloy compounds used? Because they allow you to solder an aluminum product at temperatures up to 400 degrees. This does not produce qualitative changes in the properties of the metal and maintains its strength.

Compositions with cadmium and tin do not create sufficient contact reliability and are susceptible to corrosive effects. Refractory materials containing zinc, copper, and aluminum-based silicon do not have these disadvantages.

Electrochemical method

This procedure requires a plating facility. With its help, copper plating is carried out on the surface of a product or wire. In its absence, independent processing of the part is used. To do this, apply a few drops of a saturated solution of copper sulfate to the area cleaned with sandpaper. After this, the negative pole of an independent power supply is connected to the workpiece.

They can be a battery, an accumulator, or any electrical rectifier. A cleaned copper wire with a diameter of about 1 mm, located in an insulated stand, is connected to the positive terminal. During the electrolysis process, copper will gradually deposit on the part, after which the area is tinning and dried using an electric soldering iron. After this, you can easily solder the tinned area.

Solders, materials, fluxes

Soldering of aluminum with tin is carried out subject to the use of highly active fluxes, as well as good cleaning of parts of the parts. Such tin compounds require additional coating with special compounds, since they have low strength and poor protection against corrosion processes.

How to solder aluminum elements? High-quality solder joints are obtained by using solders with silicon, aluminum, zinc, and copper. These materials are produced by both domestic and many foreign manufacturers.

Domestic brands of rods are represented by the most used solders TsOP40, which according to GOST contain 60% tin and 40% zinc, as well as 34A (aluminum - 66%, silicon - 6%, copper - 28%). The zinc used gives high strength to the contact area and provides good corrosion resistance.

Imported low-temperature alloys with excellent characteristics include HTS-2000, which provides maximum ease of use.

These alloys are used to work with large-sized parts (radiators, pipes) with high heat dissipation using a heating pad or objects made of aluminum alloys that have a fairly high melting temperature. Novice repairmen can familiarize themselves with the soldering process by watching an instructional video. This will help to avoid many unpleasant nuances during the work process.

In addition to solders, aluminum soldering requires the use of special fluxes containing ammonium fluoroborate, zinc fluoroborate, as well as triethanolamine and other elements. The most popular is the domestic F64, which has increased chemical activity. It can be used even without first removing the oxide film from products. In addition to it, 34A is used, containing lithium, potassium and zinc chlorides, as well as sodium fluoride.

Preparation of products

Reliability, as well as excellent quality of connections, is ensured not only by using the right technology, but also by preparatory work. These include the treatment of sealed surfaces. It is necessary to remove contaminants and thin oxide films.

Mechanical processing is carried out using sandpaper, a metal brush, stainless steel wire mesh or a grinding machine. In addition, various acid solutions are used for cleaning.

Surface degreasing is carried out using solvents, as well as gasoline or acetone. On the cleaned aluminum area, an oxide film appears almost immediately, but its thickness is significantly lower than the original one, which facilitates the soldering process.

Heating tools

How to solder aluminum at home? Electric soldering irons are used to solder small-sized aluminum products at home. They are a universal tool, quite convenient for soldering wires, repairing small tubes and other elements.

They require a minimum of working space, as well as the presence of an electrical network. Repair of large-sized products and welding are performed with a gas torch that uses argon, butane, and propane.

To solder aluminum objects at home, you can use a standard blowtorch.

When using gas burners, it is necessary to constantly monitor their flame, which characterizes a balanced supply of oxygen and gases. With the correct gas mixture, the fiery tongue has a bright blue color. A dim hue, as well as a small flame, indicate an excess of oxygen.

Technological process

The technology for soldering aluminum objects is similar to the process of joining parts of other metal materials. The first step is to clean and degrease the areas of future adhesion. Then the connected elements are installed in working position for ease of processing.

Flux is applied to the prepared area, and the initially cold product begins to heat up using an electric soldering iron or a torch. As the temperature rises, the solder bar begins to melt, which must constantly touch the surface of the elements, controlling the heating process.

Soldering aluminum elements at home with an electric soldering iron is done in a well-ventilated room, as hazardous compounds are released during operation.

Using flux-free solder requires compliance with some nuances. To prevent the oxide film from interfering with the alloy getting onto the parts, the end of the rod makes scratching movements along the area where the elements are soldered. This breaks the oxide integrity and the solder comes into contact with the metal being processed.

Destruction of the oxide layer during soldering can be done using another method. To do this, the area to be treated is scratched with a metal brush or a stainless steel rod.

To ensure maximum strength of aluminum parts in the soldered area, the treated areas are pre-tinned. Compliance with the technology of soldering aluminum elements guarantees excellent quality of the connection, as well as its protection against corrosion.

Source: https://oxmetall.ru/pajka/kak-payat-alyuminij

How to solder aluminum at home with a soldering iron

:

Aluminum is highly durable and a good conductor of heat and electricity. It has a low specific gravity, is easy to process, and is environmentally friendly. However, all these positive qualities create almost insurmountable obstacles when solving the problem of how to solder aluminum at home with a soldering iron. This cannot be done using traditional methods, so you have to use special welding methods and optimally selected materials.

Technical difficulties in soldering aluminum products and parts

Soldering aluminum structures and other elements is always quite difficult, especially if it is done at home by novice craftsmen who have not fully studied the process. Basically, such soldering is performed industrially using special equipment. However, it is quite possible to create the most suitable conditions for welding parts made of aluminum.

To achieve this goal, it is necessary to resolve several technical problems:

• The biggest problem when soldering is caused by oxidation in the form of a film that appears on the surface as a result of contact between aluminum and air. Even if the metal is prepared, a coating forms on it almost immediately afterward. Such a film coating interferes with the joining process and adds many problems during the tinning and soldering process. In this situation, conventional types of solders and fluxes are completely unsuitable, since they do not guarantee a high-quality connection. The film is removed either by physical-mechanical means or with the help of strong chemicals.
• One should also take into account the high temperatures at which aluminum begins to melt. It reaches a maximum of 6000C. A temperature difference arises between the metal being soldered and its film, causing difficulties in the soldering process.
• Due to the temperature regime, aluminum begins to noticeably lose its strength during the heating process. This moment occurs when the material being welded is heated to 250-300 degrees. Some aluminum alloys contain components whose melting point differs from the base metal.
• Weak interaction of aluminum with traditional types of solders, consisting mainly of tin, cadmium and other elements. This leads to insufficient strength characteristics and reliability of the created seams. The problem of how to solder is solved using special solders containing zinc, which, in turn, has excellent contact with aluminum and penetrates into it. Adhesion occurs at the molecular level, providing the necessary strength of the connection.

Preparation for soldering aluminum parts

Great importance is attached to preparing aluminum for upcoming soldering.

There are several ways to do this to ensure connection reliability:

• The connection area is pre-degreased and treated with rosin. After the substance is applied to the surface, sandpaper is placed here. Next, you need to turn on a powerful soldering iron and press the sandpaper firmly against the surface.
• After this, the surface is rubbed and polished, and the joint itself is simultaneously tinning. An aluminum part is installed on the prepared surface, which can be soldered according to the usual scheme. If necessary, rosin can be replaced with oil used in sewing machines.
• In the second option, metal shavings are added to the rosin, after which the resulting mixture is applied to the surface of the future joint. The soldering iron tip needs to be well heated and tinned, and then rub it over the entire working surface of the parts to be soldered until the chips melt. At the same time, solder is added here. In this case, the oxide is removed mechanically, and the solder immediately falls on the surface and protects it from the reappearance of the oxide film.
• The third method is to pre-clean the surface. For this purpose, copper is used, through which the oxide film is removed. This method is one of the most difficult, since copper plating of the surface must be carried out in a special bath.

Selection of solder and flux for aluminum

Tin- and lead-based solders can be used to weld wires, elements and parts made of aluminum, provided they are thoroughly cleaned. Such soldering must be carried out using special flux solutions consisting of highly active substances.

However, such connections have insufficient strength due to the weak interaction of aluminum products with tin and lead, and the tendency to form corrosion. Therefore, special compounds are used in the form of anti-corrosion coating for surfaces made of this metal.

These compounds include solders containing copper, zinc, aluminum and silicon. They are produced both in our country and abroad. Among domestic brands, the most widely used is TsOP-40, which contains 40% zinc and 60% tin, as well as compound 34A with aluminum (66%), copper (28%) and silicon (6%). zinc affects not only the strength of aluminum contacts, but also their resistance to corrosion.

Of all the known solders, the minimum temperature at which they begin to melt is those based on tin and lead. The highest melting point belongs to compounds with an aluminum-silicon structure, as well as with aluminum, copper and silicon.

In the first case, similar types of solders melt when the temperature reaches 590-600 degrees, and in the second - at 530-550 degrees.

They are selected for each specific case, when parts with large dimensions, with good heat dissipation or refractory aluminum connections are connected.

Technological processes are inextricably linked with special types of fluxes used for better interaction of all welding components.

Selecting the most suitable material is considered a rather difficult undertaking. This is especially important when the process uses tin-lead solder. The structure of such fluxes includes elements that form its increased activity when interacting with aluminum. Among them are triethanolamine, ammonium fluoroborate, zinc fluoroborate and other similar components.

One of the most popular flux substances produced in Russia is the F64 substance, which is characterized by high activity. The quality of this connection allows you to solder metal parts made of aluminum without removing the refractory oxide coating located on the surface.

Soldering aluminum components

The procedure and technical process for welding aluminum are exactly the same as for other types of non-ferrous metals.

Among home craftsmen, the following two options are most often used:

• High-temperature soldering used for welding large-sized elements. This category includes aluminum structures with thick walls and increased mass, which require a temperature of 550-6500C to heat up.
• Soldering at low temperatures of 250-3000C, which is quite enough for installing wires of electronic equipment and welding small items used in everyday life. Aluminum wires are connected in the same mode in any electrical network.

Connections at high temperatures occur using special heating elements. One of them is a burner, which requires gas in the form of propane or butane to operate. If such a burner is not available, home craftsmen use various types of blowtorches.

Welding at high temperatures requires constant control over the degree of heating of the surfaces of the parts being joined. To do this, take one of the refractory solders in a small amount, and after it begins to melt, we can talk about reaching the desired temperature.

In this case, the heating of the part stops, otherwise it will simply melt and collapse.

Soldering at low temperatures is carried out with a 100-200 W electric soldering iron. The power of a soldering iron depends on the size of the components being connected: the larger the part, the more powerful a soldering iron will be required to heat it up. The conductors are easily connected with a 50 W soldering iron.

Regardless of the temperature conditions, connections are made in the same way, and all actions are performed in the following order:

• The place of future connection of parts or cables is processed mechanically. For this purpose, any cleaning agents are used that weaken oxidative deposits, providing more complete interaction with the flux substance.
• The joint must be degreased with acetone, gasoline, alcohol and other organic solvents.
• Before soldering aluminum with a soldering iron or torch at home, the parts are firmly fixed in the most convenient position.
• Flux is applied to the prepared surface. If the substance is used in liquid form, it is applied with a brush.
• The connection point is heated using an electric soldering iron of sufficient power or a gas burner. Next, molten solder is applied here and distributed in an even layer.
• Metal surfaces are connected and fixed in the desired position.
• After the solder has cooled and the parts have set, the joint is washed with running water. Flux residues are washed away and do not cause corrosion in the future.

Source: https://electric-220.ru/news/kak_pajat_aljuminij_v_domashnikh_uslovijakh_pajalnikom/2018-11-20-1605

Soldering aluminum at home

instrument.guru > Metalworking > Soldering aluminum at home

Soldering aluminum at home is a real way to repair household utensils, household and automobile aluminum radiators, pipes, plumbing fixtures and much more. In industrial conditions, soldering and welding of parts made of this material is carried out using automated equipment. At home, soldering and welding aluminum is also possible.

• Preparing for work
• Determination of product alloy
• Solder selection
• Flux selection
• Tool selection
• Aluminum soldering process
• Product preparation
• Soldering the product
• One home method on how to solder aluminum with a soldering iron

To do this, use an ordinary soldering iron, ordinary POS-50 and POS-61 solders containing tin. In addition, it is possible to use a magnesium welding stick or use a gas torch.

Once you have chosen your solder, you need to select a soldering flux. The biggest secret when soldering aluminum is to work quickly , connecting the parts to be soldered immediately after they have been cleaned of oxide.

Determination of product alloy

It is necessary to determine the alloy of the parts being soldered, as far as possible, whether it is aluminum at all or not. Many aluminum items and parts in the household are aluminum alloys.

Many alloys can be successfully soldered at home using a home vice and a soldering iron. But some alloys can only be welded on an industrial welding machine. The composition of an aluminum part can be guessed based on the hardness of the material.

The softer the material appears when processed, the greater the amount of pure aluminum it contains. This is a condition for successful and high-quality rations.

Solder selection

1. If you are soldering aluminum with other metals, for example, aluminum and copper wires, then this soldering requires a special approach. Often in such cases, the aluminum wire itself, a small section of it, is covered with a layer of copper. Then they tin with regular solder and solder the wires.
2. Low temperature solder is required for soldering.

   Since the melting point of aluminum is 660 ºC, and it has good thermal conductivity, a necessary condition for successful soldering with a soldering iron is the need for a sufficiently low-melting solder containing tin, which means fast melting of the solder. In many cases, POS-50 solder is quite suitable. It is also possible to use POS-61 solder.

3. You can purchase special solders for soldering aluminum. These are alloys of aluminum with silicon and zinc.

   They are different, depending on what you will be joining - aluminum to aluminum or aluminum to copper and other materials. You must carefully read the label on the package.

Flux selection

It is necessary to select a suitable flux for soldering aluminum. Aluminum can be soldered in different ways.

Due to the fact that the main problem when soldering and welding aluminum is the removal of the oxide film from the surfaces of the parts being joined, different fluxes are used for different soldering methods. At home, use regular rosin or alkaline oil.

A saturated solution of copper sulfate is also used. In addition, regular sewing machine mineral oil, which can be purchased at a hardware store, is often used. It is applied directly to the aluminum.

Tool selection

• You need to choose the right heat source. For small parts, a soldering iron with a working power of up to 150 watts is quite suitable, but for massive parts, for example, a car radiator, a low-temperature gas burner is required. Its operating temperature is 315–425°C. It can provide good heating of the soldering areas of the product and rapid melting of the solder.
• Buy or collect additional equipment.

  When you join aluminum, you will need some kind of clamp or vise. In addition, after completing soldering, it is necessary to rinse the soldered surfaces in water or detergent to remove any remaining acid or oil fluxes. If a resin-based flux was used, then you need to wash the aluminum with acetone. Accordingly, this requires some kind of container or bath.

• Take care of your safety. Create a comfortable work area. Be sure to purchase a respirator mask to protect against toxic fumes. Work only in a well-ventilated area. When using liquid, and especially acidic fluxes, use a mask or safety glasses.

  When using a gas burner, aluminum can melt, so when working you need to use cotton overalls and boots.

Product preparation

1. Before joining the pieces aluminum, it is possible to pre-tinning these pieces. This is useful when soldering complex structures. In this case, it is very easy to tighten the aluminum in a clamp and then solder it with a soldering iron or gas torch. Accordingly, this does not need to be done if you are sealing cracks or holes in one product.

2. Next, you need Clean the aluminum and its surface to be treated using a stainless steel brush. When exposed to air, aluminum quickly becomes coated with a layer of aluminum oxide, which cannot be tinned or soldered. Another condition for high-quality soldering is that you need to be prepared for quick cleaning, fluxing and soldering so that the aluminum does not have time to become covered with a new layer of oxide.

   A product that is heavily soiled or oxidized needs to be sanded and wiped with isopropyl alcohol or acetone.

3. Clamp soldered metal parts together. You need them to touch in the place where you want to solder them. For solder you need to leave a small gap, less than 1 mm. If the metal parts do not touch smoothly, then you need to make the ground areas smooth.

   There is another way to work. Since when working with aluminum you need to work quite quickly, you can lightly clamp the aluminum pieces together in a vice, clean them there, and then tighten the vice clamp firmly.

4. Next, quicklyBefore a new layer of aluminum oxide has formed, apply flux along the soldering area. To do this, you can use a wooden stick or a solder rod.

   This will ensure that the solder is drawn out over the entire joint area and a strong solder seam is achieved.

Soldering the product

Now you can heat the parts to be soldered. To do this, you can use a soldering iron with a power of up to 150 watts or a gas torch, depending on the mass of the product being soldered.

• Heat should be near the joint. You need to start heating from the lower end of the product. The direct flame of the torch can overheat the connection, and then all the work will go down the drain. Therefore, the torch tip must be kept at a distance of 10 - 15 mm from the metal surface. In order to evenly heat the seam being soldered, it is necessary to smoothly move the heat source in small circles across the soldered area. Please note that when using a soldering iron, it may take 10 minutes for it to reach the desired operating temperature. If, when heating the joint being soldered, the flux used turns black, this means that the heating temperature of the joint was too high. The flux must be removed and, after cooling, a new one must be added and work continued.
• After warming up the work area to the desired temperature, you need to apply solder. The heating temperature is determined by the color of the flux. In general, fluxes that are used for soldering aluminum become light brown in color and begin to bubble when they reach operating temperature. Bring the solder to the soldering area while continuing to heat the area indirectly from the opposite side of the part or a nearby surface. Continuing to move the soldering iron or torch along the soldered seam, it is necessary to achieve uniform spreading of the molten solder over the entire area of ​​the soldering area and the formation of a shiny, mirror-like surface.
• If a new layer of aluminum oxide has time to form on the surfaces to be soldered before applying the flux, the solder will not bond to the aluminum. Then the surfaces of the parts need to be cleaned again, flux added and soldered again. This situation may arise if the type of solder and flux are not suitable for working with aluminum and its alloys. Or the aluminum alloy of your product is really poorly soldered.
• After cooling the part to be soldered, it must be cleaned of any remaining flux and oxides formed at high soldering temperatures. If the flux used was water-based, it can be washed off with water or a neutral detergent. If the flux was made based on resin, then acetone can be used for cleaning. Sometimes an acid etching solution is used to remove oxides.

One home method on how to solder aluminum with a soldering iron

You need to prepare a small surface on an aluminum product by simply cleaning it. Apply a few drops of a concentrated solution of copper sulfate to this surface. Connect the aluminum product using a wire with a diameter of approximately 1 mm to a direct current source. Aluminum wire can be used. Fold the other copper wire to form a small disk. Connect the other end of this wire to the “+” DC source.

An ordinary incandescent lamp can be connected in series to this circuit at the appropriate voltage. A transformer rectifier from 3 to 12 volts, a rechargeable battery or even a flashlight battery with a voltage of 4.5 volts is suitable as a power source.

There are many videos online on . Here are instructions for successfully soldering aluminum.

After turning on the power source, the copper wire with a rolled up disk is brought to the soldering site a short distance and lowered into the previously applied solution of copper sulfate. There is no need to touch the aluminum product itself; the current must flow through the copper sulfate .

The light comes on and copper is electrolytically deposited onto the aluminum surface. After some time, the copper sulfate may boil and evaporate. Precipitated copper will remain in its place. Then this area can be tinned in the usual way and a copper wire can be soldered to it.

Source: https://instrument.guru/metalloobrabotka/pajka-alyuminiya-v-domashnih-usloviyah.html