Features of soldering brass at home: solder and equipment. Brass soldering technology How to solder a brass fitting screwed into metal
In previous articles, we examined electric soldering irons and gas burners used in soldering, and also got acquainted with solders and fluxes.
Important!!! Use ONLY LEAD-FREE solder for all work on food equipment.
Do not forget that when soldering, hot objects, aggressive liquids, voltage 220 V are used. Be extremely vigilant, be careful.
In this material, let's move on to practice and solder copper. Along the way, consider the features of its soldering.
Soldering copper and brass is not very different from each other. The main difference is the thermal conductivity, which is several times higher for copper. Therefore, brass is even easier to solder a little.
Copper and brass are soldered with tin solder, rosin, phosphoric and soldering acid are used as a flux. You can solder with aspirin, but this is an extreme case.
I prefer to solder copper with phosphoric acid without having to clean it mechanically.
Consider the example of a soldering of two copper tubes between themselves..
First, you need to expand one of the ends. I used thin nose pliers for this purpose.
The second end, on the contrary, is slightly undermined so that it enters the extended part.
Before soldering, the contacting parts of the tubes must be tinned, that is, covered with a layer of tin. Yes, not just cover, but cover with high quality so that the metals do not peel off from each other. To do this, the surface to be tinned must be heated to at least the melting point of the solder. And since copper has a very high thermal conductivity, it will be very difficult to warm up even a not very thick tube with one soldering iron.
For preheating, I use a gas burner, and only then quickly apply the flux and apply and spread the solder with the tip of the soldering iron.
At the same time, overheating a part is just as bad as not overheating it. I am guided by the color of copper, as soon as it starts to darken a little, that means enough.
A well-tinned surface has a uniform luster, and does not lag behind the tube even with heavy scratching.
It can be quite simply done at home, although many craftsmen do not dare to do such work, being afraid of certain difficulties that may arise in the process of its implementation.
Meanwhile, the brass soldering technique is quite simple and does not require any special training.
Most often, brass soldering is performed with an ordinary gas burner, and for these purposes, tin, brown or other similar material can be used as solder, which can replace traditional flux.
It should be noted that this work can also be done with a special graphite electrode or a soldering iron, using the appropriate solder.
At its core, the soldering of this material is somewhat reminiscent of the soldering of steel, copper or cast iron, however, it has some features and subtleties that must be taken into account without fail.
It should be noted that brass parts are easier to machine than steel, copper or cast iron parts.
A feature of soldering brass, cast iron or copper at home, unlike steel, is that an oxide film forms on their surface, which affects the quality of the connection being made.
Despite this, at home, with the right approach to business, it is possible to solder brass blanks with a drill, as well as copper parts, not only with a gas burner, but also with a soldering iron, unlike cast iron or steel, which are welded exclusively with an electrode.
Soldering is inherently the most optimal way to obtain a sufficiently strong and permanent connection, both parts made of brass and blanks made of other materials, including cast iron. Welding with a graphite electrode, in turn, requires certain skills and training.
When making a connection between the elements, molten solder is necessarily introduced, and for this you can use tin or borax.
The solder should have a melting point slightly below the melting point of the base material.
With the help of soldering, it is possible to firmly connect the most different materials, including parts made of cast iron or copper.
Very often this is the only way to carry out bonding. metal surfaces various types.
Of course, soldering in some way can be compared in a certain way with welding, when the surfaces are joined by an electrode, but in this case only the final result is common.
The essence of the soldering process itself is completely different.
The main difference between welding and soldering is that when connecting surfaces with an electrode, the base material melts, and when working with a soldering iron, only the bond metal melts.
In addition, a flux must be present in the soldering, which can be a borax.
Of course, soldering provides a less durable connection of aluminum, copper or cast iron surfaces than, for example, welding, but it allows you to work even with small workpieces.
This can be explained by the fact that the flux used in soldering, which can be a drill, under the influence of relatively high temperatures, releases certain chemical elements, which reduce the strength of the main joint, in addition, the seam itself turns out to be porous.
Soldering aluminum, like, for example, welding cast iron, is best done with an overlap rather than a butt.
Despite the fact that soldering is somewhat inferior to electrode welding in terms of joint strength, it is currently actively used in various industries.
With the help of it, the necessary fastening is carried out not only of brass blanks, but also of copper and even cast iron products.
Most often, various types of metals are soldered with a soldering iron, but if necessary, a gas burner can also be used for these purposes.
To perform soldering, including brass blanks, solder or flux is required without fail, which very often acts as a drill.
It should be noted that welding can be both high-temperature and low-temperature. At home, the first soldering option is used.
In the video above, you can see how brass blanks are soldered.
Material characteristics
In general, brass is an alloy of copper and zinc. Especially often it is used for the production of various household utensils, pipes, radiators and many other devices.
The home craftsman very often has to deal with the need to carry out the appropriate surface treatment of brass, and therefore it is necessary to know all the features of this specific metal.
To perform soldering of a brass surface, it is very important to choose the right flux, and in this case, a drill is best suited, which can effectively remove the formed oxide film from the surface.
You can buy this flux, the role of which is played by the drill, in almost any hardware store at an affordable cost. The borax-based flux allows for better flow of the main binding component into the formed gaps.
Also with special care should be selected and solder for brass.
So, if this work will be performed in a gaseous environment, then in this case it is best to use silver or copper-phosphorus solders.
Such solder is also excellent for working with brass, which has a high copper content. In this case, you can use a solder based on brass itself with a lower melting point.
With special care and caution, solder and flux should be selected when it is necessary to connect parts from completely different materials.
So, for example, the quality of soldering brass and copper directly depends largely on the type of solder that will be used, as well as flux (borax).
It is these components that mainly affect the quality of the weld and its porosity.
When soldering brass in a gas environment at home, it is recommended to use a specific flux, which in some cases can be replaced with a thin layer of materials such as nickel or copper.
This will avoid the release of zinc contained there from the brass surface, respectively, and the connection itself will turn out to be more durable and of high quality.
Currently, you can buy solders, which in their composition contain elements that replace ordinary flux.
This makes it possible to significantly simplify the work, make it better and faster.
Copper-phosphorus composition can act as such a universal solder.
Operating procedure
After all the properties of the materials used in the process of soldering brass are analyzed and studied in detail, you can proceed directly to the process itself.
First you need to prepare all the required tools and material. A gas torch or soldering iron should be on hand, as well as the appropriate solder and flux.
These materials should be selected as carefully as possible, so that in the end the seam is of the highest quality and dense.
In some cases, solder for brass can be prepared independently and for this it will be necessary to take copper and technical silver in certain proportions, melt them in a special crucible and mix thoroughly.
When the molten mixture becomes completely homogeneous, the container with it will need to be placed in cold water until it cools completely.
When preparing solder with your own hands, special attention should be paid to the uniformity of its structure, since the quality and strength of the future connection will largely depend on this.
In this case, you should not save on consumables and opt for cheaper and lower quality components.
In turn, soldering flux is prepared from borax and boric acid, which can also be completely freely purchased at any hardware store.
These components are taken in equal proportions and filled with ordinary water.
After all the necessary components are ready for soldering brass, you can proceed directly to the work itself.
For this, a brass billet is taken, previously cleaned of dirt and various oil stains, and gently sprinkled with crushed solder.
After that, a gas burner is activated, with the help of which the working surfaces are heated to a certain temperature.
The main thing here is not to overheat the brass part so that it does not burst and deform.
If the brass surfaces are thick, then they must be warmed up gradually.
For more information on how to solder brass without assistance at home, see the video in our article in detail.
Brass parts, unlike steel, are easy to machine, and it is because of this useful quality of the alloy that brass can be soldered at home, without recourse to industrial methods. To create a wide variety of things, soldering is necessary - connecting wires and metal parts. To be correct, it is necessary to have gas burner, graphite crucible, asbestos base, as well as silver, copper and boric acid.
Soldering brass is much easier than soldering steel, which makes it possible to do it at home.
Preparation for soldering brass products
Oxalic acid can be used to clean the alloy. If it was not at hand, you can see various household products. They are applied to brass products, after which it will quickly begin to darken. Then you can get rid of plaque by taking a thin brush and cleaning the parts in ordinary water. Following this, you will need soda, which is poured into a brass product. After a few minutes, the soda is washed off. In the presence of oxalic acid, it is diluted in proportions of 20 grams per liter of hot or cold water. It is not recommended to breathe over the solution, and you should also protect your hands with gloves. The container must be plastic to avoid exposure to other metals. Once the brass part has been finished, it should be wiped down and dried.
Oxalic acid is used to clean the alloy.
To solder brass most effectively, you should not use ordinary tin soldering, as after its use quite noticeable traces remain. In addition, she cannot boast of great strength. In order to braze brass, it is recommended to use a different method that provides increased reliability. Effective and reliable soldering of brass parts is ensured by the use of a gas burner. To make solder from brass, you should take copper and silver in proportions of 1: 2, mix thoroughly and fuse together using a graphite crucible and a gas burner. The crucible is placed in a container with cold water, and only after that it is possible to extract the molten and solidified solder. It must be flattened and cut or ground into chips, which can be done with a large file. After that, you will need borax powder and boric acid, each ingredient should weigh 20 grams. Based on these substances, flux is produced. The resulting powder mixture is poured with water with a volume of a quarter liter.
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Solders for soldering brass parts
Soldering with a gas burner must be done very carefully, with maximum temperature at 700 degrees.
Brass parts that require soldering are placed on an asbestos base. The connected parts are sprinkled with solder, cut into small pieces and pre-sharpened. The joint is then gently heated using a gas burner. This work must be done with the utmost care. When soldering parts, the temperature should smoothly approach a certain level. Maximum allowable level is 700 degrees, but if you overcome it, you can face hopeless damage to all the details. When it is necessary to solder large and massive parts, their heating should be gradual in order to avoid negative consequences. When soldering small and thin parts, the heating process occurs in a very short time, so it is important to be careful about it.
Of course, conventional soldering with tin is much easier than with a similar method, but it is thanks to it that the reliability and strength of soldering brass parts will be much higher. It is important to remember some features of brass soldering, for example, the evaporation of zinc in a very hot state. In addition, the surface of the alloy is covered with an oxide film. Brass, which contains less than 15% zinc, oxidizes and becomes covered with a film in which there are adherent particles of copper oxide and zinc oxide. Copper alloys, in which zinc is contained in much larger quantities, oxidize to form a film consisting mainly of zinc oxide. The problem with these alloys is that copper oxide is easier and faster to remove than zinc oxide.
The finished product is washed with hot 3% sulfuric acid.
If ordinary low-temperature soldering is carried out, in which solder containing lead and tin or other tinols is used, the oxide film must be removed from metal surfaces. Here it is possible to use rosin-alcohol or more active fluxes. To process brass with a high zinc content, for example, L63, it is necessary to use a flux, which includes zinc chloride. It is important to remember that brass has some of the worst melting qualities with tin-lead solders. This feature leads to the fact that during the soldering process, intermetallic layers slowly begin to grow. They have a positive effect on the weld, and one can expect an improvement in the mechanical properties of metals.
You should not hope that soldering, in which tin-lead solders of brass L63 are used, will lead to high-quality connections. Their adhesive strength and quality will be inferior to copper if the conditions are the same. The tensile strength index in relation to copper parts soldered with tin will reach 90 MPa, and for brass parts it will not even reach 60 MPa. The soldering of brass parts, in which there is a high content of copper, can be carried out with solders PSR 72, 45, 25 and 12. Sometimes in such cases it is permissible to use copper-phosphorus brass or a brass alloy that melts at a low temperature. This is mainly applicable to gas soldering.
With a high level of zinc, it is possible to use PSR 40 solder. The use of phosphorous solders is completely unsuitable, because there is a high probability that a solder joint with low ductility will appear. This is due to the formation of zinc phosphides, which are characterized by their brittleness. Hard solder is also very common, used when connecting large products, for example, to work with brass and copper pipes and heating systems generally. The advantage of hard solders lies in the high strength of the joints obtained.
The method of strong soldering of products from various metals It is carried out by heating the parts to be soldered with a gas burner and using brass as a solder. With the mass distribution of copper car radiators, soldering with brass was the only reliable way to fix a leak. Such soldering is widely used in the manufacture and repair of household and industrial equipment, air conditioners. In addition, brass soldering allows you to securely fasten refractory cutting parts to the body of the cutter or drill string. Soldering with brass allows you to assemble small hand-forged art products (chandeliers, fireplace grates, etc.).
Materials and tools
Soldering with brass is carried out using three main components: a gas burner that gives a temperature of at least 1000 degrees.
Brass solder (in the form of wire or tape).
And flux - sodium tetraborate or borax, mixed with boric acid powder.
Modern household gas burners use purified propane, sold in mini cylinders, or special blends gases. More complex burners with separate gas and oxygen supply speed up heating and the entire soldering process.
The need for this flux is due to the zinc content in brass. Zinc, when melting brass wire without borax, causes the solder to boil, which affects the quality of the seam and its strength properties.
In addition to the main components, we need auxiliary tools:
- sandpaper and files for cleaning parts;
- various vise and clamps;
- restraining hand tool(pliers, long nose pliers, etc.);
- liquids for degreasing and washing and removing scale from finished seams (acid solutions);
- fireproof gloves and others individual means protection used in welding.
Brass soldering process
It is necessary to prepare the parts to be soldered. Let's say we need to make a small frame structure from thin-walled steel tubes with a diameter of about 5 mm. When soldering two tubes of small diameter end-to-end, you need to make a notch at the end of the tube to be soldered. This will increase the strength of the connection. The parts must be placed in the clamping devices and the connections pressed together. This is necessary condition performing high-quality soldering with brass solder, as the hands will be busy with the torch and solder supply.
We light the gas burner and begin to heat up the place of soldering until a red color appears.
We also heat the brass wire (solder) and lower the heated end of the solder into the borax. Borax sticks to the solder wire.
We briefly move the flame of the burner aside and apply the flux directly to the junction of the steel pipes. Borax quickly melts and covers the entire soldering area. If you do not remove the flame, then the borax will simply be blown off the brass wire.
After that, soldering begins - the slow melting of brass solder, its manual supply and filling the joint between the parts with it.
During the work, visual control over the quality of the seam is carried out. If a fistula is found in the lower part or an area not covered by solder. It is better to turn the part over and solder this place again.
After stuffing the hand, you can also solder the "ceiling" joints. Soldered parts must cool in the air.
Then you need to remove the scale by placing the part in a solution of edible citric acid.
To check the quality of the seam, bend the product.
Very durable!
Precautionary measures
Soldering with brass refers to open fire work. All fire protection measures must be strictly observed. In addition, work with zinc vapor can cause severe poisoning of the body. Protective measures must be taken. Mini gas cylinders can have valve leaks, causing explosions and fires. It is necessary to constantly monitor the operation of the gas burner.Brass is an alloy, the essential components of which are copper and tin. Possessing high strength, ductility and corrosion resistance, it is well suited for the manufacture of both heavily loaded parts of various mechanisms and structural elements operating in aggressive environments. Its main disadvantage is its high cost. But there are other problems associated with the use of this material.
To date, various technologies have been developed that allow welding brass products. But all of them are quite complex, costly, and require that the specialist who performs the work has certain skills. An alternative to welding is often brass brazing. It is somewhat simpler technologically and imposes other requirements on the qualifications of the performer.
Encountering Obstacles
If the zinc content in the alloy is low, then there are no special problems. It is possible to cope with the task with the help of ordinary rosin. But in the case when the amount of zinc exceeds 15%, the use of special fluxes is mandatory. This is due to the fact that evaporating when heated, zinc and copper form a strong oxide film on the surface of the part, which is very difficult to remove.
Choose ready-made or make your own?
The simplest flux for soldering brass is easy to make yourself. To do this, you need to mix borax and boric acid powder in a one-to-one ratio, pour the resulting amount of water at the rate of 5 ml per gram of the powder mixture, gently stir, boil, and then cool. But ready-made formulations that go on sale have the best characteristics.
- One of the most common is the "Bura" flux. Invented a long time ago, this recipe has received the approval of many jewelers involved in soldering various metals, including brass. It belongs to the category of high-temperature mixtures that are activated when reaching 700 - 900 degrees Celsius. Despite his advanced age, he performs his work qualitatively.
- Fluxes of the PV-209 and PV-209X brands do their job well. The first is based on fluorosalts, and the second is made using hydrofluoric acid. Both also work at temperatures approaching a thousand degrees.
- Somewhat less heating will be required by Chemet FLISIL-NS-Pulver (powdered) and Chemet FLISIL-NS-Paste (paste) produced in Germany. For them, 550 - 800 degrees Celsius will be enough. They work best when using silver-containing solders.
The brands listed are examples only. There are many options on the market for this essential product for brazing brass.
What kind of solder to take
Just as important as the choice of flux is determining the right solder composition.
- For soldering brass with a copper content, PMC-48 solder is well suited, the melting of which occurs at 870 - 880 degrees. PMC-36 has a slightly lower melting point. Both compositions belong to the group of copper-zinc solders.
- Marks MF-1, MF-2 and MF-3 belong to the group of copper-phosphorus solders. They are relatively inexpensive, ductile, but have high electrical conductivity and resist shock and vibration loads worse than compositions containing silver.
- Silver solders have the best mechanical properties. Among them are PSr-10, PSr-12m, PSr-25 and beyond, up to PSr-72. All of them have some differences in chemical composition and melting temperature. They also react differently to the percentage of copper and tin in the metal being joined.
From the foregoing, it is clear how important it is to decide on the brand of brass before proceeding with the choice of flux and solder. Only then will it be possible to achieve an acceptable soldering result.
Training
Before starting work, it is necessary to properly clean the junction from contamination. To do this, you can use a variety of tools - metal brushes, special nozzles, files or sandpaper. After that, the treated metal must be degreased. If you do not do this, you will make your work more difficult, and the soldering, if it can be done, will not have sufficient strength.
The parts to be soldered must be laid on a thermally insulating lining. Strange, but many sources still recommend sheet asbestos, recognized as a carcinogen, for this purpose. Undoubtedly, it is worth finding a replacement that is not harmful to health. For example, based on fiberglass or carbon fiber.
Soldering iron or torch?
The use of an electric soldering iron is acceptable when flux and solder with a melting point of about 500 degrees Celsius are used. But even in these cases, the power of the device must be at least 100 watts. It is better if this figure is 0.5 kW and above. After all, the soldering place must be preheated well.
Joining massive parts or soldering thick brass is more convenient with a gas burner. In this case, it is possible to heat the metal so that the use of high-temperature components becomes possible. The connection zone is treated with a flux, and sprinkled with crushed solder on top. Only after that proceed to the heating of the metal. This must be done with extreme caution. First, preheating is performed, allowing the flux to become more active, and the solder to grab onto the surface. Gradually, the temperature is increased until the brass acquires a characteristic redness. It is at this moment that the solder spreads, filling all the small pores in order to securely connect the parts when cooling. If everything is done correctly, then after a gradual cooling, you will get a neat seam, the color of which will be close to the color of brass.
Application area
It is quite obvious that brass soldering is easier than welding, not only at home, but also in production. The resulting connection will have sufficient strength. However, it is still not worth counting on the fact that it will withstand very high loads. Based on this, the scope of the technology is also determined.
- Manufacture of electrical and electronic components. Mechanical loads in this case are low, and electrical conductivity comes to the fore. We should not forget how difficult it is to use welding to connect small parts.
- Connection of elements subjected to small and medium loads. This includes parts of small mechanisms like clocks, or components of pipelines operating at pressures not exceeding a few atmospheres.
- Jewelry production. Of course, the cost of brass is much lower than that of silver or gold. And yet, it is quite often used to make inexpensive rings, brooches and other jewelry, becoming, if not their main part, then at least a component of frames and clasps.
- Do not forget the restoration work. Sometimes soldering brass is the only way to restore a thing that was made many years ago.
There was an application of such a technique in mechanical engineering. Making a new one with it, or soldering a damaged brass radiator is much easier than using welding. The efficiency and durability of the resulting part will be significantly higher than that of cheaper aluminum counterparts.