How to solder aluminum with a torch

Principles of aluminum soldering

Soldering aluminum is a complex process, since an oxide film forms on the surface, which interferes with the work. Therefore, it is necessary to use special techniques to simplify the workflow. Special fluxes will allow you to get rid of the negative factors of the oxide layer.

Process Features

The surface of aluminum parts is covered with an oxide film, which has high chemical resistance, as well as a melting point 2 times higher than pure metal. In the range from +2500С to +3000С aluminum becomes unstable and melts. The minimum melting temperature of the oxide film is +5000C.

When soldering, the parts being connected under the outer layer begin to melt. Therefore, the shareholder needs to eliminate the negative impact of the oxide layer. The principle of all methods is based on film removal, as well as increasing adhesive properties.

Methods for removing the oxide layer:

• mechanical - the use of abrasive tools for stripping;
• chemical - the use of fluxes with special compositions;
• electrochemical - based on electrolysis processes.

Both methods are carried out only in an environment without oxygen.

Materials used

To complete the work you will need to prepare the following materials:

To obtain high-quality seams, you need to use a flux for soldering aluminum based on zinc, silicon, and copper. The joints are strong, durable, resistant to corrosion, static and dynamic loads.

Solders with the following markings are suitable for soldering aluminum:

• TsOP-40 - refractory tin-zinc composition;
• POS - light alloy solder;
• 34A - alloy based on copper and silicon;
• “Aluminium-13” is a foreign analogue of 34A.

The use of flux improves the adhesion of metal to solder, resulting in a strong connection. The durability of the seam, the strength characteristics of the product, and the resistance of the material to the negative influences of the external environment depend on its choice. Fluxes contain active elements: zinc or ammonium fluoroborate, triethanolamine.

Solder fat comes in the following types:

• neutral based on rosin and stearin - it is thick, capable of removing small contaminants, and adheres well to the surface of the metals being welded;
• active with a complex chemical composition - effectively removes oxides and traces of corrosion, increases soldering properties.

The fat contains zinc and ammonium chloride, paraffin, and auxiliary substances.

Solder fat has the following advantages:

• easy tinning due to spreading in a thin layer;
• availability;
• dosage accuracy;
• no traces after use.

It is recommended to use the following brands of fluxes: F-64, F-61A, F-59A, 34A, F-5, F-124.

Scope of the process

Brazed aluminum products are used in the following areas:

• automotive industry;
• radio electronics;
• production of window frames;
• production of bicycle parts;
• creating frames for greenhouses and equipment buildings.

Soldering methods

There are the following soldering methods:

• with rosin;
• with solder;
• electrochemical.

With rosin

Step-by-step implementation of the method:

1. The soldering iron is warming up.
2. The tip is tinned to remove dirt or carbon deposits.
3. Rosin is applied to the joint seam and melted with a soldering iron.
4. After melting, use a sting to rub the surface until the oxide film is removed. At the same time, tinning occurs.
5. After the process is completed, the elements are joined, heated to the melting point, and then left to cool.

Using solders

The method using solder for soldering aluminum is implemented as follows:

1. The joining surfaces are cleaned mechanically.
2. The parts are securely fixed.
3. Local heating of the structure is performed.
4. The rod with solder is guided along the joint seam, simultaneously heating it with a burner until it melts.

If solder without flux is used, it will need to be used separately. It is pre-applied in an even layer on aluminum.

Electrochemical method

Step-by-step electrochemical soldering of aluminum:

1. The surface is cleaned of dirt, partly of the oxide film, mechanically.
2. Apply a thin layer of copper sulfate.
3. The negative electrode of the current source is connected to the part.
4. The positive electrode is connected to a high purity copper wire (diameter greater than 1 mm). It is located above the structure on a special stand, ensuring contact only with the treated area.
5. The power source turns on. The electrolysis process begins to take place.
6. After removing the oxide film, the wire is removed, and the parts are heated with a soldering iron to the melting temperature or solder is used.

To ensure high quality soldering, it is necessary to apply galvanic coatings with special tools. They will allow for uniform copper plating.

Preparing parts

In preparation for work, it is necessary to use the following surface treatment methods:

• degreasing is carried out using a solvent, using acetone, white spirit, gasoline;
• the oxide film is removed using abrasive tools or a soldering iron or gas torch is used to apply flux.

ALUMINUM SOLDERING. NO ARGON NEEDED!

General principles of soldering aluminum at home

Basic principles of soldering aluminum at home:

• it is necessary to perform high-quality cleaning of the metal surface from contaminants, coatings, and oxide films;
• the time interval between cleaning and soldering should be minimal;
• to remove the oxide film, it is better to use metal brushes or soldering irons with special attachments;
• the choice of heating tool is made depending on the soldering area, since aluminum cools quickly due to its high thermal conductivity;
• if there is no suitable solder, then it is allowed to use any solder that contains tin or lead;
• when heating parts for applying solder, it is important not to overheat aluminum, since it has a lower melting point compared to the oxide film;
• tinning the aluminum surface with a continuous layer will eliminate the appearance of oxides, which will simplify its soldering;
• when using a burner, it is important to follow fire safety rules, especially when applying degreasing solvents;
• soldering can be performed in several layers, before applying each you need to wait until the previous one hardens;
• the use of flux will require the use of protective equipment, since it may contain caustic substances;
• the burner flame should always be directed in the direction opposite to itself;
• For soldering, it is recommended to use soldering irons with a power of more than 100 W;
• flux is used mainly for elements with a thickness of 4 mm or more or surfaces with complex shapes;
• The composition of the solder is selected based on the type of soldering, but the melting point is always lower than that of aluminum;
• to solder workpieces with a thickness of more than 4 mm, along the edge of the butt seam you need to cut the edge at an angle of 450 to increase the contact surface;
• After carrying out the work, it is necessary to ensure the integrity, strength, and uniformity of the seam.

When choosing solder, you need to consider the type of tool used for melting.
Alloys with low melting points are suitable for a soldering iron: tin alloys with copper, zinc, bismuth. To create a refractory compound, you will need a complex alloy of aluminum, copper, and silicon. Verified! Soldering aluminum at home

Principles of aluminum soldering Link to main publication

Source: https://metalloy.ru/obrabotka/pajka/alyuminievyh-izdelij

How to solder aluminum with a torch - Metals, equipment, instructions

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 you use a special flux for soldering aluminum, as well as the appropriate solder, then this technological process does not present any particular difficulties.

Soldering aluminum using a propane torch

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

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

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 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

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.

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.

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 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.

How to solder aluminum to aluminum

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

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://moy-instrument.ru/masteru/kak-spayat-alyuminij-s-alyuminiem.html

How to solder aluminum with a gas torch - Technique Expert

Aluminum is a metal that is difficult to solder. This is due to its tendency to form a strong oxide film on the surface of products, which prevents the part from being wetted by molten solder.

Mechanical cleaning of the surface alone does not help, since new oxide is formed instantly after removing the old one. For this reason, special fluxes are used for soldering aluminum and special technology is followed.

Connecting wires

Typically, aluminum soldering is used in cases where the parts to be joined are small enough and the use of argon welding is impossible or absent. One example of the use of soldering is connecting electrical wires made of different materials.

Often in practice it is necessary to connect copper and aluminum wires. Such connections cannot be made by twisting, since this pair of metals forms a source of electrochemical corrosion . In this case, soldering aluminum to copper can be an excellent connection option.

This operation can be performed with ordinary soft lead-tin solder, but you should use a special flux for soldering aluminum. The procedure must be performed in the following sequence:

• first you need to strip the copper wire and tin it using rosin;
• to tinning an aluminum wire, after mechanical stripping of the oxide film, it should be coated with a layer of flux for soldering aluminum;
• for better mechanical strength of the connection, tinned wires can be twisted;
• By heating the joint with a soldering iron and adding flux, the solder melts and a solder is formed.

The connection obtained in this way can be safely embedded in the wall; it will last for a very long time.

Removing the oxide film

Usually, if you have a good flux specifically designed for soldering aluminum, the use of any special tricks is not required; it is enough to mechanically clean it and moisten the surface to be soldered with flux.

It is also possible to use acid for soldering aluminum. They use hydrochloric acid in which zinc is dissolved (soldering acid), and fluxes based on orthophosphoric acid are also used.

But if such a flux is not available or, due to poor quality, does not provide soldering, you can go another way. There are several ways to remove the oxide film for successful tinning of the workpiece.

In rosin

An aluminum wire or other part can be freed from the oxide film by immersing it in liquid rosin. To do this, you can either melt it or prepare an alcohol solution.

After immersing the part in rosin, use a sharp knife to scrape off the oxide film. The rosin layer prevents the access of air and the formation of new oxide. After this, the part can be tinned using a heated soldering iron with solder.

Abrasive powder

In the absence of flux and rosin, aluminum soldering can be done as follows. A paste is prepared consisting of abrasive powder and transformer oil.

Fine metal filings can also be used as an abrasive. The workpiece is coated with this composition, after which it is rubbed with a hot soldering iron with solder.

As a result of this, the abrasive grains or metal shavings remove the film, and the surface is immediately wetted with solder without access to air. After tinning, the product can be easily soldered.

Chemical cleaning method

In essence, this method is nothing more than copper plating of an aluminum surface. It is performed as follows.

That part of the aluminum billet that is to be coated with a layer of copper is moistened with a solution of copper sulfate. Then take a direct current source with a voltage of 4.5 volts.

This could be a battery or accumulator. The aluminum part is connected to the negative terminal of the power source. A copper wire is connected to the positive terminal, the end of which is entangled in the bristles of a toothbrush.

Next, the brush is moistened with a solution of copper sulfate. The wire located in the bristles must be well moistened. After this, rub the area of ​​the part previously moistened with the solution with a brush.

As a result of the galvanic reaction, the surface of the aluminum is coated with a thin layer of copper, allowing it to be soldered as if it were a copper part.

Warming up the part

When soldering fairly massive parts, the power of a conventional electric soldering iron may not be enough to heat the workpiece to the required temperature.

You can use a gas burner to heat aluminum at home. For this purpose, it is better to use a portable burner powered by a small gas cartridge. In this case, you need to work very carefully. It is unacceptable to overheat the base metal to the point where it begins to melt.

You can also use a combined heating method. For example, place a massive aluminum piece on the burner of a kitchen gas stove and light a small fire. You can use an electric soldering iron at the soldering site.

Everything that has been said about methods for soldering aluminum applies to various alloys based on this metal. Only the topic of silumin soldering is somewhat isolated. This material is an aluminum alloy containing silicon (roughly speaking, sand).

Soldering this alloy presents particular difficulties. Attempts to solder silumin often fail.

Even after seemingly successful soldering, it turns out that the connection does not have the required strength and may break. Experts do not recommend soldering this material. The best way to join this alloy is argon arc welding.

High temperature process

Industrial methods of aluminum soldering are distinguished by the use of harder solders containing aluminum. To use this technology, factory equipment and special fluxes are required.

Thus, heating and soldering of workpieces is carried out in special tunnel-type furnaces. The soldering process is carried out in an environment of inert gases at temperatures reaching 600 ℃. This technology is used in the manufacture of aluminum radiators and heat exchangers of modern cars.

Source: https://kumselstroy.ru/drugie/kak-payat-alyuminij-gazovoj-gorelkoj.html

How to solder aluminum with a torch - Metalworker's Guide

The process of soldering aluminum is a very popular process, both at home and in industrial areas, since thanks to it it is possible to connect various small parts, but one also has to deal with larger parts. There are many types of metal welding, but sometimes soldering is used for a more suitable and high-quality connection.

In this regard, soldering aluminum with a gas torch is considered a very popular method, since there are several advantages that are not known to beginners. Soldering aluminum is not very convenient, unlike other methods, however, it is still preferable to others, since at high temperatures the structure of the metal changes with the use of welding, so it is not used.

The essence

To carry out a quality process, it is necessary to use various auxiliary devices that are required by technology that has existed for a long time.

When soldering aluminum, significant difficulties arise with the oxide film on the metal surface, which forms almost immediately, and even after preparatory procedures. Carrying out the soldering process using a torch is considered much more convenient than using a soldering iron, since there is the necessary temperature adjustment, thanks to which it becomes possible to more accurately process the surface of the metal, both thin and thick.

Quite often in such cases, flux and various chemicals are used for processing. When soldering aluminum with a gas torch is carried out at home, preheating the metal, as well as melting additional consumables, is easier.

It is known that aluminum is one of the metals that melt easily, making working with them difficult, since the metal becomes highly fluid; a lot of experience is required to carry out a high-quality process. When the metal begins to spread over the surface, it will not be able to fill the seam, much less seal holes and cracks, so the necessary skills will be required.

There are many types of metal soldering, so the correct choice of filler material is important, and solders must be selected accordingly to the upcoming process.

Thanks to aluminum soldering, it is possible to connect both different mechanism housings, including thick sealed containers, and ordinary wires.

Soldering aluminum wires is quite easy using a torch, since there is the necessary adjustment of the flame temperature, as well as its intensity.

Advantages

• The process of soldering aluminum using a gas torch is considered universal compared to using a soldering iron, since it is possible to connect both thin and thick different parts;
• Thanks to a gas burner, it is possible to carry out the necessary regulation of the intensity of the flame, thanks to which you can determine the temperature, while when using a soldering iron, you will need to have some devices of various powers available;
• A gas burner can provide the necessary heating of the surface of the material, melting the solder and flux;
• The process of soldering with a gas torch takes a correspondingly long time, so it becomes possible to form a better-quality connection;
• After completing the process, the connection result will be much better than using a soldering iron;
• With such a device, you can almost immediately carry out new work without waiting for the tool to cool down.

Flaws

• Preparatory work takes a very long time;
• Prices for performing such work are very expensive, unlike other methods;
• Such a process is very unsafe, since due to the container in which the gas is present, an explosion can occur when exposed to an open source of flame, and cracks can also form in the hoses over time, which has a negative effect on the respiratory system;
• The cost of equipment for work is very expensive.

Materials and accessories

• The main device for soldering is a gas burner; gas flows through it under pressure. During the soldering process, it exerts a temperature effect, due to which the solder metal melts, and it is also possible to heat the material. By adjusting the pressure supply as necessary, the flame temperature can be determined;
• A gas cylinder, the size of which may not necessarily be standard. The cylinder contains consumable flammable material, so it must be isolated at a safe distance from flames;
• The hose that goes from the cylinder to the burner. Before starting the process, it is recommended that they always pay attention, checking their connections, as well as the integrity of themselves;
• Solder for soldering aluminum, which may vary depending on the upcoming procedures. Before soldering with a gas torch, filler wire is also required depending on the base material;
• Flux, which improves the soldering process. This substance is mainly used for joining thick workpieces, but is also used for soldering various types of metal, such as aluminum, or in particularly difficult cases.

Torch soldering modes

Workpiece thickness, mm	Solder consumption, g	Gas consumption, ml
1-2	0,5-1	3-5
2 -4	1-1,5	5,5
6	1,5	7
10	2	11

Step-by-step instruction

1. Before starting the soldering process, it is necessary to carry out preparatory procedures. It will be necessary to clean the metal surface with a fine metal brush if the workpiece exceeds 4mm in width; in other cases, sandpaper is used. Then it is necessary to remove various deposits such as grease and oxide film, as well as possible contamination using various chemicals such as solvent, acetone and others.
2. Then you will need to apply flux to the future joint of the metals, which will improve the soldering properties and fluidity of the metal;
3. Then you will need to heat the upcoming workpiece using a burner so that the solder has the opportunity to melt and spread over the surface;
4. Then you can directly begin the soldering process by bringing the filler material in the form of wire or solder to the surface of the metal and igniting the burner. Using the temperature effect of the burner flame, it is necessary to melt the metal so that it spreads over the surface and hardens there. If you need to apply several layers, this can be done in stages;
5. At the end of the process, when all the cracks and holes are filled with filler material, forming a smooth surface, it is necessary to give time for the fabrication to cool down, and then check the quality of the connection.

Safety precautions

At the beginning of each use of the equipment, it is necessary to check the integrity and serviceability of the gas cylinder and hoses. The cylinders will need to be placed at the required distance of at least 5 meters from such work and the source of flame. It is not recommended to leave various flammable objects or flammable substances near the cylinder.

Source: https://ssk2121.com/kak-payat-alyuminiy-gorelkoy/

Do-it-yourself methods for soldering aluminum (solders and fluxes)

Aluminum is a rather specific material that requires special processing methods. If there is a need to connect parts made of this metal, the use of technologies that have proven themselves when working with copper or brass is unjustified. And yet, you can solder aluminum! The main thing is to choose the right materials and tools.

Accurate information

First, if possible, you should determine exactly what alloy the parts to be connected are made of. Indeed, in its pure form, aluminum is used extremely rarely in electronics and technology. Much will depend on what chemical elements and in what quantity it is mixed.

• Critical melting point. Some additives significantly increase this limit, which for pure metal is 658 - 660 degrees Celsius.
• Mechanical properties. Depending on their composition, some alloys become more ductile, while others demonstrate increased strength.
• Interaction with other chemical elements.

Knowing in advance what material he will be working with, the master greatly simplifies his task.

Why do you need flux?

The main obstacle when soldering aluminum is its oxide film. The statement that it can be removed mechanically is untenable, since a new film appears almost instantly. That is why, with rare exceptions, it is impossible to perform work without the use of active fluxes. The purpose of these fluxes is to destroy the Al2O3 barrier so that the metal can seamlessly combine with the materials that make up the solder.

If you wish, you can make your own flux for soldering aluminum. But this matter is quite complicated, and therefore it is easier to purchase a ready-made composition. Moreover, the industry produces them in sufficient quantities. Among the fluxes there are both widespread and highly specialized ones. In the annotations to them, bona fide manufacturers indicate the purpose and features of the proposed product. Among the most common are:

• F-64. It is capable of destroying a strong oxide film of considerable thickness, and therefore is well suited for soldering even large parts. Moreover, it is suitable for working not only with aluminum, but also with galvanized iron, copper, beryllium bronze, etc.
• F-34A. This composition is successfully used with refractory solders containing a significant amount of chemical additives.
• F-61. It can be recommended for low-temperature soldering or tinning of products made of aluminum alloys.
• Castolin Alutin 51 L. This composition works best when using solders from the same manufacturer.

The final choice of flux brand depends on many factors. Before deciding whether a composition is unsuitable, it is worth making sure that all important technological requirements are met.

After the oxide film is destroyed, solder comes into play. As with flux, its composition should be given the most careful attention. Operating at different temperatures, these materials must perform the main task of connecting to the metals being processed.

The use of low-temperature compounds is not justified, since they can be destroyed when heated during operation. The most common are mixtures with medium and high melting points. But the final choice will depend on many factors.

Domestic solders TsOP-40, containing tin and zinc in a percentage ratio of 60 to 40, and 34A, the use of which is justified when using gas-flame heating, have proven quite good. However, under certain conditions, solders Germanium-1 and Germanium-2, V-62, P550A, P575A and others are quite capable of competing with them. Many of them are made mixed with fluxes, which makes them easier to use. But there are also flux-free solders, such as those containing aluminum and zinc

Source: https://svarkalegko.com/tehonology/pajka-alyuminiya.html

Soldering aluminum with a gas torch

The need for soldering various parts arises both in domestic and industrial settings, since this process can be classified as minor repairs, although one often has to deal with larger-scale procedures. The fact is that various types and methods of metal welding cannot always provide results of decent quality, and are also not always suitable.

Therefore, soldering aluminum with a gas torch is a very popular method, which still has a number of its own features that beginners will have to master. The fact is that the solderability of this metal is not as good as that of other varieties, but soldering becomes more preferable, since when strongly heated, the metal changes its structure and welding spoils its properties, so welding cannot always be used.

To maintain quality, all available additional tools should be used, which are provided by the infrastructure developed over a long time.

Soldering aluminum with a gas torch

When working with aluminum, problems arise in the fight against the oxide film, which covers the metal in a relatively short period of time, so that it can appear even after pre-treatment.

Soldering with a torch is noticeably different from soldering with a soldering iron and is considered a more convenient process, since here you can regulate the temperature and the master gets more opportunities for delicate surface treatment, both thin and thick metal. Often at this time additional fluxes and various processing agents are used.

Soldering aluminum at home with a gas torch makes it easier to preheat the metal and melt additional consumables.

DIY aluminum soldering

Naturally, to obtain a high-quality connection, work experience is required, since aluminum is a low-melting metal, and accordingly, its solders have high spreadability. If done incorrectly, the material will simply spread over the surface, never filling the joint, let alone filling holes where real skill is required.

A very important point here is the selection of filler material, since each type of soldering requires its own solder. Aluminum can be used to create the body of a mechanism or any thick sealed container, as well as ordinary wires.

Soldering aluminum wires using a torch is easier due to convenient regulation of the flame temperature and its intensity.

Advantages

• Soldering aluminum with a torch is universal, unlike using a soldering iron, and can be used for both thin and thick parts;
• A gas burner has the ability to adjust the intensity of the flame, which determines the heating temperature, whereas when working with a soldering iron it is necessary to have several tools of varying power;
• With a burner you can heat the surface of the metal, melt solder and flux;
• The speed of work is slower, so it becomes possible to do everything more efficiently and calmly;
• The final results are higher quality than using a soldering iron;
• The tool is ready for use almost immediately and there is no need to wait long for it to cool down after work.

Flaws

• Preparation for work takes a longer period of time;
• The cost of the soldering process becomes higher;
• The work becomes less safe, since the container containing the gas may explode if exposed to an open source of fire, or the hoses may leak gas, which will also cause harm to the body;
• Equipment for the job is more expensive.

Materials and tools

• The main tool is a gas burner, which passes gas under pressure through itself. During combustion, it melts the solder metal and acts as the main heat treatment force. By adjusting the pressure supply, the overall flame temperature is determined.
• A container of gas, which can be represented by a small cylinder. There is consumable flammable material here, which must be reliably isolated from external influences.
• Hose for connecting the burner and cylinder. It itself, as well as the connections, should always be checked for integrity before use.
• Solder for soldering aluminum, which is selected according to the type of procedures with which there will be interaction. When soldering aluminum with a gas torch, the filler wire is selected according to the composition of the base metal.
• Flux to improve soldering properties. It is primarily used for thick workpieces, but is also used for brazing various types of metal, such as torch brazing of aluminum to steel, or particularly difficult cases.

"Important!

The melting point of the wire should always be lower than the melting point of the base metal.”

Step-by-step instruction

1. To begin with, the metal surface is prepared, for which purpose the surface of the part is pre-cleaned with a fine metal brush or sandpaper. You also need treatment with a solvent, which will help eliminate deposits of fat and oil, remove oxide film and other negative effects.
2. Then it is necessary to treat the entire surface where soldering will take place with flux. This will help improve the soldering properties, flow and wettability of the material.
3. Afterwards, you need to heat the workpiece with a burner so that the solder can better melt and spread over the surface.
4. After this, you can begin soldering by bringing the solder or filler wire to the surface of the workpiece and lighting the torch. By treating with a burner flame, melt the material so that it spreads over the surface and hardens there. Applying several layers can take place in several stages.
5. At the end, when the consumable material fills all the cracks and grooves, forming a smooth surface, you need to let it cool and check the quality of the connection.

Soldering aluminum with a torch

"Important!

If the thickness of the part is more than 4 mm, then you should start cutting the edges, since aluminum will not be soldered otherwise.”

Soldering and soldering for aluminum when working at home

Aluminum and its alloys are very light and durable structural materials. Aluminum structures and parts can be found everywhere: on production sites and in every home. Repairing equipment and household items requires welding or soldering. Welding is a complex technological process used in enterprises. And you can solder and tin pots, flasks, and aluminum tubes at home.

Soldering technology

Difficulties that arise when soldering aluminum elements are due to the physical and chemical characteristics of the material. The main difficulties encountered during soldering are caused by:

• Low melting point of aluminum and alloys.
• Rapid oxidation with the formation of a hard film on the surface of the material.
• Good thermal conductivity, which is associated with rapid temperature distribution.

To create a strong connection, you need to determine what kind of material you will have to deal with. Pure aluminum is used quite rarely, and the additives used to produce different alloys greatly affect the characteristics of the material, namely:

• The melting point of pure aluminum is 660 °C, and for alloys with a high content of magnesium and silicon, the melting point is 500 °C.
• Mechanical properties change. An increase in magnesium content significantly increases the strength of the material.
• Corrosive properties change.

Based on operating temperatures, a distinction is made between soft soldering (150–300 °C) and hard soldering (390–580 °C). All these factors must be taken into account when choosing fluxes and solders for specific applications.

Types of fluxes

The main difficulties when soldering aluminum products are associated with the appearance of an oxide film on the surface. It can be removed mechanically using an iron bristle brush or scraper, but it immediately forms again. Therefore, an active flux for aluminum is needed that can destroy the film and create conditions for joining the product material with the solder.

Source: https://pochini.guru/sovety-mastera/payka-i-pripoy-dlya-alyuminiya

Soldering aluminum at home with a gas torch

Soldering aluminum at home can be considered a difficult task. But with the right approach and compliance with the appropriate technology, it is quite possible to perform it even for an inexperienced master.

Soldering aluminum at home

Problems often arise when using the wrong flux, for example when soldering steel or copper. It is very important to use a special substance for soldering aluminum, as well as suitable solder. If they are used, soldering aluminum will not cause any particular difficulties.

Features of aluminum soldering

Soldering aluminum at home can be accompanied by some difficulties that are associated with the special characteristics of this metal. In particular, with the fact that the surface of aluminum parts is covered with an oxide film.

It interferes with the process of making connections due to its high melting point, exceeding the properties of pure aluminum. Also, the oxide film is resistant to aggressive environments and active chemicals.

Because of this, the film prevents the connection of aluminum parts and solder.

To avoid such difficulties, it is worth cleaning the surface of products from film, which can be done using abrasive materials or using flux. Flux consists of potent substances that can destroy the oxide.

The melting point of aluminum, unlike oxide, is much lower, approximately 660 degrees, which often causes complications. When overheated, aluminum can significantly lose strength, become deformed, or become completely unusable.

Melting point of aluminum and its oxide film

The use of solders that contain such components should be avoided. They do not bond well with aluminum, which causes a poor-quality connection.

Zinc, which has good solubility, interacts best with aluminum.

Soldering methods at home

There are several methods of soldering, the most popular are methods using a soldering iron and soldering aluminum with a gas torch. There are three ways to solder parts:

1. Soldering with rosin is used to join small aluminum parts, wires and cables. To do this, you need to clean the work area and cover it with rosin. Then press with a heated soldering iron several times. For these purposes, you need to use a rosin solution in diethyl ether.

Aluminum soldering process

Soldering is performed without removing it from the work area, followed by the addition of rosin. It is recommended to use a soldering iron with a power of 50 W. If the thickness of the parts and wire exceeds 1 mm, the power should be increased to 100 W, and it is better to warm up thicker objects in advance.

This method is most widely used in electrical work and soldering of automotive parts. Before performing work, parts must be tinned. This allows you to connect parts with other alloys and metals. In this case, aluminum is soldered with tin or solder containing zinc and cadmium. This allows connections to be made at temperatures of 400 degrees, which does not affect the physical properties of aluminum.

1. Solder is necessary when using almost all soldering methods, whether using a soldering iron or a torch.
2. The electrochemical method involves the creation of galvanic coating, which is performed using a special installation or manually. To do this, you need to apply a solution of copper sulfate to the cleaned surface. After this procedure, the parts are exposed to a negative electric pole.

Materials and tools

To perform aluminum soldering, you must have various materials and tools, which include heating tools, solders and fluxes.

Required materials and tools

An electric soldering iron is most often used as a heating tool. It can be considered a universal tool that is easy to use at home. But with its help you can only repair small items, usually small-diameter pipes, wires and cables, as well as small electrical appliances. It can be used at home in a ventilated area, as it does not require special conditions and a lot of space.

Large items should be soldered using a gas torch running on argon, propane or butane. At home, you can also use a blowtorch.

When using burners, it is necessary to strictly control the supply of flame, which should be characterized by maintaining the balance of gas and oxygen. When carrying out work, the flame should be bright blue. Any color changes may indicate too much oxygen.

Solders for soldering aluminum

Soldering aluminum is a very difficult task. Therefore, the choice of solder is important to create a high-quality seam and a strong connection. When using a conventional soldering iron, you need to select solder from a metal that has a low melting point. The most common alloys are:

• zinc-tin;
• bismuth-tin;
• copper-tin.

These types are often called amateur radio. They have a low melting point, which is very important for maintaining aluminum in its original state without changing the structure and physical properties. The cost of such solders is low, so their purchase becomes affordable for home craftsmen.

Solders for aluminum

But their use has a number of disadvantages and a limited scope of application. Thus, connecting objects using such solder is not highly durable and reliable. Therefore, they are used almost exclusively when repairing electrical equipment, including connecting wires and cables.

When repairing large aluminum objects using such solders, the connection will quickly lose strength and collapse. In such cases, it is better to use refractory solder, which contains zinc and tin.

But to create strong connections, refractory solders containing aluminum, copper and silicon should be used. Due to the presence of aluminum in the composition, the solder dissolves well in the structure of the repaired item.

It is impossible to use such solder when working with a soldering iron, since their melting point is about 600 degrees. Therefore, to work with them you need to have a gas burner.

It should be noted that when soldering using a gas torch, the metal of the workpiece does not melt; only the solder will melt.

Fluxes for aluminum soldering

When soldering aluminum, you need to use special fluxes, since not every flux is active towards aluminum. The most suitable substances are those based on ammonium fluoroborators and triethanolamine. Most special fluxes are marked with special markings, which indicate the possibility of their use when soldering aluminum.

Fluxes for aluminum soldering

If it is necessary to work at high temperatures, you should pay attention to mixtures containing potassium chloride, which makes up half; potassium chloride; sodium fluorite and zinc chloride. This composition allows you to create the most optimal conditions for high-temperature work.

Soldering aluminum at home

Soldering aluminum at home can be considered a difficult task. But with the right approach and compliance with the appropriate technology, it is quite possible to perform it even for an inexperienced master.

Soldering aluminum at home

Problems often arise when using the wrong flux, for example when soldering steel or copper. It is very important to use a special substance for soldering aluminum, as well as suitable solder. If they are used, soldering aluminum will not cause any particular difficulties.