✅ How to melt brass on a gas stove - construction goods44.rf

In its most basic sense, brass is an alloy whose main component is copper. Additional metals can be such as zinc, tin (there should not be too much of it so that the alloy cannot be called bronze), to a much lesser extent manganese, lead and even iron. In ancient times, this alloy was often called orichalcum, translated as “golden copper”. However, the alloy does not belong to bronze according to the classification, since if we compare the melting point of brass and bronze, it will be much higher for the second.

Like bronze, brass has a fairly wide range of applications in various fields . It is used mainly in the automotive industry in the manufacture of some bolts and other parts, for the manufacture of memorial signs and awards, pipes, and sleeves for chemical equipment. Very often used to create interior items or individual furniture elements.

Physical features of melting homogeneous metals

Brass is a multicomponent alloy based on copper and zinc. It may also contain some other components - tin, lead, iron, nickel, manganese. Copper acts as the main substance, while additional components improve the physical properties of the material (strength, elasticity, electrical conductivity, corrosion potential). Melting of single-component and multi-component alloys has many differences. Therefore, before considering the issue of melting brass, it is necessary to consider the features of melting a homogeneous metal based on copper.

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In physics, smelting is a procedure in which a solid metal turns into a liquid state. To melt copper, it must be heated to a temperature of 1.085 degrees Celsius. Typically, heating is carried out with a small temperature increase (

1150 degrees), since in practice copper alloys are often used with the addition of alloying substances, which increase the melting point.

Heating at the chemical-physical level

Copper atoms are in a solid state before heating. On a chemical level, this means that they form a strong crystal lattice that is resistant to deformation and retains its shape upon impact.
When heated, the potential energy of copper atoms increases, which leads to a deterioration in the strength of the crystalline structure of the material. However, the material retains its hardness because the crystal lattice is not destroyed (although it becomes less dense).
When the temperature reaches 1.085 degrees, the copper atoms receive an excess amount of energy, which causes the crystal lattice of the alloy to disintegrate. At the physical level, the alloy changes from a solid to a liquid state.
Now several situations are possible. Let's consider the first situation. If the material continues to be heated, it will retain its liquid state. At a temperature of 2.567 degrees, copper goes into a gaseous state (that is, the liquid begins to boil). In metallurgy, evaporation of copper is very rarely performed, since it has no practical benefit.
But another situation is also possible. If liquid copper is not heated after melting, then the liquid will gradually begin to cool. This will cause the material to return to a solid form. At the chemical level, the crystal lattice will re-form.

One simple conclusion can be drawn from these theoretical calculations. For one-component compositions, the crystallization temperature and melting temperature are the same. In practice, it is simple to regulate the melting procedure - you just need to reduce or increase the temperature of the fire. During work, it is also necessary to monitor the distribution of fire over the entire area of the metal object. If the temperature distribution is uneven, some components will be in a liquid state, while others will be in a solid state.

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How is brass melted in metallurgical plants?

The alloy is usually melted in metallurgical plants, since favorable conditions for remelting are created there. During factory melting, the material retains all its physical properties - strength, electrical conductivity, retention of shape during deformation, and so on. The technology for remelting brass at a factory depends on what category of brass the material belongs to. Two-component alloys (with added zinc) are usually melted in induction furnaces that have quartz-lined walls. This coating minimizes overheating of the furnace and also protects the walls from deformation and cracking.

Double brasses melt at relatively low temperatures (the liquidus point for them is in the region of 910-930 degrees Celsius). Therefore, there is no point in melting dual alloys in powerful electric arc furnaces. For the melt, it is recommended to use a charcoal-based protective layer. It is also recommended to introduce a small amount of cryolite into the melt (about 0.01-0.1%) - this helps reduce metal defects during smelting. Instead of charcoal, you can use a flux consisting of glass and spar in a 1 to 1 ratio.

To remelt two-component brass, you must first melt the copper and then the zinc. To melt metal, you need to heat it to a temperature of about 1000-1100 degrees. After this, zinc and alloying additives, if available, should be added. Please note that there is no need to deoxidize brass, since zinc performs this function perfectly.

Complex non-siliceous brass

Melted according to a similar algorithm. These alloys contain zinc in small quantities. Therefore, such a metal must be deoxidized in order to preserve all its beneficial physical properties. Phosphorus is suitable for deoxidation, although other deoxidizers can be used. When melting, complex brass often produces large debris fractions - to get rid of them, you should perform manganese refining or filtration.

Complex silicon brasses

They have complex crystallization dynamics, which is explained by the presence of silicon and aluminum additives in the alloy composition. Due to the presence of these components, the alloy has an increased tendency to absorb atmospheric hydrogen at high temperatures (more than 1000 degrees).

When the alloy is heated to temperatures above 1100 degrees, batch releases of dissolved carbon may occur, which can lead to the formation of “blisters” on the alloy after it hardens. Therefore, approach the remelting of silicon steels responsibly. To avoid the release of dissolved carbon, smelting should be carried out in an acidic environment. Saturating the air with an acid flux based on sodium carbonate, calcium fluoride and silicon oxide works well. It is important to monitor the heating temperature, since the protective properties of the gas oxidizer noticeably decrease when the temperature reaches 1100 degrees.

After melting all components in a protective environment, it is necessary to perform a mandatory check of the metal for all main indicators (fracture, saturation, presence of contaminants, and so on).

What you need for smelting

You can melt brass at home with a gas torch. It is installed vertically under the crucible. To reduce heat loss, the heating zone is shielded with refractory materials or thick iron.

It is convenient to use a factory-made compact muffle furnace. If you have to do home smelting of metals, this item is worth purchasing. Owners of private houses build a furnace from fireclay bricks with air blowing. They immediately make a frame for installing the crucible and a lid.

It is necessary to prepare a refractory crucible. You can use ready-made ceramic, which can withstand temperatures up to 1300°C, or graphite, it is very reliable, suitable for reusable use, the main thing is to remove the slag in a timely manner when it is just gone. Craftsmen make crucibles themselves from fireclay chips, silica, liquid glass, and coat the finished mold with talcum powder. Long tongs are used to grip the hot crucible. It is advisable to prepare a powerful stand that is difficult to melt.

To cast parts, molds are made:

from plaster, they stick it on a wax copy of the future part;
a mixture of cement and brake fluid.

These molds will need to be placed on sand or a large fireproof stand and will need to be filled with the molten substance.

To remove slag from brass you will need a spoon or a wire loop. Don’t forget about fire safety and your own safety.

Mold casting: manufacturing, sand, shell molds

According to historians, the bronze casting is 12 thousand years old. Initially, using this technology, jewelry and simple tools were made from bronze. Over time, this technology has been improved, and today it is a method by which many unique products are created from this alloy.

The current level of development of bronze casting makes it possible to produce various objects from this copper alloy not only in production, but also at home.

Thanks to the invention of bronze, as well as the development of its processing technologies, the main of which is casting, we can still enjoy the sight of works of art that were created by masters back in the Middle Ages and ancient times.

Antique bronze set of writing instruments

Bronze casting, as well as brass casting, another alloy based on copper, gained the greatest popularity in the era of classicism and European Baroque. It was in those days that people learned to use these materials to create unique interior elements and decor.

Such alloys created on the basis of copper are still actively used in the manufacture of:

items used for interior decoration;
gates and fences that perform not only a decorative, but also a protective function;
sculptural compositions and souvenirs;
bas-reliefs and design elements of lighting fixtures - chandeliers and sconces;
elements of staircase structures and entrance groups.

Bronze casting for making knife handles

Many of these products, which are not large in size or complex in shape, can be made from bronze and brass not only in production, but also at home.

Stages of artistic bronze casting

In order to perform high-quality casting from a metal such as bronze, it is necessary to adhere to a certain sequence of actions. First of all, you should reflect in the sketch the shape of the product that you plan to cast from bronze.

Based on the sketch, which is created by professional artists and designers at modern enterprises, specialists create a drawing that accurately reflects all the dimensions of the future casting.

It is the drawing that is the basis for making an accurate model, which is used to produce a casting mold.

To create a model of a product that will subsequently be made from bronze by casting, various materials can be used, in particular:

Ivory;
wood (in this case, preference is given to such varieties of this material as pine, alder, beech, linden);
gypsum;
various types of polymer materials.

The cavities of the wax model of the future figurine are filled with clay, which will be removed after casting

To make the surface of the model as smooth as possible, it is primed, puttied and covered with several layers of varnish. When making a casting model, not only different materials can be used, but also different design approaches. So, models can be:

detachable (these are complex structures consisting of several component elements that can be connected to each other along flat or complex surfaces);
one-piece (monolithic models, the simplest type, most often used for casting at home);
special (this includes skeletal or molding templates used in cases where it is necessary to make a casting mold for the manufacture of objects with a complex configuration).

The next step after creating an accurate model of the future bronze product is the production of a casting mold. For this purpose, special devices and equipment are used, and the main materials used in this case are molding mixtures created on the basis of clay and carefully cleaned quartz sand.

The longest stage of bronze casting is molding - making a casting mold

In such a technological process as casting, made from bronze and any other metal, the casting mold plays a decisive role.

It is into such a mold, the internal cavity of which must exactly repeat the product being cast, that the molten metal is poured, and in it it cools, forming the finished casting.

Foundry molds, used both in production and at home, can be single-use or reusable, which is determined not only by the material from which they are made, but also by the features of their design.

Microcasting at home

A lot of cast parts made of non-ferrous metals and their alloys are used in technology, including quite complex and miniature ones, the serial production of which can only be afforded by enterprises with precision technology.

However, single (or even small-scale) microcasting can be organized at home.

It turns out that modern technology can be rivaled by the ancient method of injection molding using a simple manual centrifuge.

Almost everything that is needed for such micro-casting can be made by hand. Costs are minimal.

Indeed, the flask required for casting in this case is a piece of ordinary steel pipe with a diameter of 50-60 mm and a wall thickness of 2-3 mm. For casting products of different sizes, it is good to have several flasks of different diameters, provided that each one fits freely in the centrifuge bucket. If you have such a set, you can cast a whole series of parts one by one.

A centrifuge matches the flask in simplicity. Its wooden handle has a length of about 200 mm and a diameter of 20-30 mm. An M8 bolt is inserted into the axial hole of the handle. A metal earring is attached to it using a locked nut so that both the handle and the earring rotate easily without interfering with each other.

A bucket for a flask is suspended from the earring on a rocker arm made of 6 mm steel wire. The side of the bucket is made of a 60 mm piece of 80x3 mm steel pipe, and the welded bottom is made of a steel sheet 3 mm thick. The 200 mm high bow is made of the same 6 mm steel wire.

In order to confidently use such a centrifuge, you must first practice a little, remembering how in your school years in the physics room you had to twist a bucket of water on a string while studying centrifugal force.

True, now, instead of string and a bucket of water, in my hands I have a homemade centrifuge with a bucket, on the bottom of which there is a plastic cup (to prevent it from breaking).

But the water in it is ordinary, like it was in school physics experiments. And the action of centrifugal force is similar.

Holding the handle firmly, you need to rotate the entire chain (earring - rocker - bucket and vessel with water) around the bolt-axis, trying not to spill a drop.

Technology for producing high-quality micro-injection molding of non-ferrous metals and alloys using a manual centrifuge:

1 — bolt-axle; 2 - wooden handle; 3 — metal, easily rotating earring; 4 — locked nut; 5 — steel wire rocker; 6— bow; 7 — side of the bucket; 8 — bottom of the bucket; 9 — flask; 10 - molding compound; 11 — wax model; 12 — wax ball with technological wire pins; 13—casting mold with sprue channels, formed after melting the wax and removing the pins; 14—molten metal (alloy); 15 — flame of a gasoline burner; filling the mold with the melt while rotating the centrifuge and subsequent operations for removing and finishing the finished product are not shown

Once you get the hang of it, you can subsequently deal not with water, but with molten non-ferrous metal (or alloy), which will be pressed by centrifugal force through the gating channels into the casting cavity in the flask installed in a bucket instead of a plastic cup.

Perhaps the most difficult and time-consuming thing in micro-casting is the production of a three-dimensional, life-size wax model.

This one is molded from wax by hand, using a heated eye scalpel or a hot darning needle. Even small details are worked out with the utmost care, because molten metal (as well as any alloy) does not forgive mistakes and sloppiness. Moreover, casting, performed in a centrifuge under pressure, reveals all the flaws of the model!

In my practice, I use wax models whose height is no more than 40 mm and diameter is 50 mm. At the same time, I try to maintain proportionality so that the mass of metal in the casting does not exceed 40 g. The limitations are mainly due to the low power of the burner I use for melting.

Melting at home

The alloy has a fairly low melting point compared to other metals, and therefore it can be processed, manufactured and repaired even at home. To do this, it is necessary to assemble special equipment and have a large work area that allows you to comply with all safety measures required when working with hot or molten metal.

Required Tools

To melt brass at home, you need a furnace.
It can be assembled from bricks that have sufficient fire resistance, connecting it with the same heat-resistant mortar. It is best to use induction heating elements as a heating element. These are ceramic tubes on which nichrome wire is wound. They can heat up to high temperatures (1000 degrees Celsius or more) and are useful for working with other, more refractory metals and alloys. Article on the topic: How to turn on an Electrolux gas stove

The minimum required power of the electricity source that will be supplied for heating should be about 25-30 kilowatts. It must be assembled from sufficiently high-quality electrical parts and have a high efficiency rate.

The crucible - the container where the metal will actually melt, can be made from fireclay - clay fired before sintering. For additional heat resistance and reliability, you can coat it with a solution of potassium silicate, or simply “liquid glass” with an admixture of talc. Such a crucible will last much longer and withstand a greater number of melts. There are also crucibles made of graphite, but they are much inferior to clay ones in terms of reliability. For operations with a crucible, it is necessary to make or purchase forceps. They should have fairly long handles and have rounded jaws.

Process description

The alloy is placed in the crucible, preferably in the form of pieces.
The smaller they are, the easier the melting process will be, since the heat from the heating elements will be distributed faster between them. The crucible, using tongs, is placed in the oven, and only after that does it begin to heat up. It can be removed from the furnace only after the entire volume of metal placed in it has passed into a completely liquid form. This operation is performed using the same forceps. If a film has formed on the surface of the molten brass, it should be removed using a previously prepared wire. To make alloy castings, you should use special molds cut from wood or 3D printed from a material that is more heat resistant than liquid brass. Wooden molds are mostly disposable. The algorithm of actions is simple: take out the crucible, remove the film, fill it in and wait for it to cool completely.

Safety precautions

To carry out all operations with metals heated to very high temperatures, it is necessary to take care of your safety and minimize the impact of the process on health. It is worth remembering what metals brass is made of, at what temperature a particular sample melts and how it is achieved. Here are some tips:

Use protective gloves and clothing made from materials that are difficult to burn - wool, cotton and others. You should not use synthetic clothing, as it can catch fire very quickly.
Take care to protect your eyes and face with glasses and masks, as an accidental drop of molten metal can cost you your eyesight or cause a serious burn to your facial skin.
Casting must be carried out in a place with sufficient ventilation, as during the casting process substances are released that, if they acquire sufficient concentration, can cause great harm to your health.
In order to minimize the risks of arson or accidental ignition of nearby objects, you can cover the surface on which the stove will be located with an asbestos sheet. Again, do not forget about good ventilation.

By following these guidelines, you can safely and effectively handle hot or molten metals without fear of harm to yourself or others.

What is brass made of?

Brass, the alloy composition of which can vary significantly, necessarily contains copper in an amount of at least 55%. The remaining 45% of the two-component alloy consists of zinc. Zinc in the copper alloy significantly increases the mechanical strength of the alloy and corrosion resistance.

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In addition to zinc, multicomponent brass may contain:

Aluminum.
Tin.
Nickel.
Manganese.
Silicon.

Additional additives are necessary if it is necessary to provide the metal alloy with new properties that will facilitate easier formation of the product during casting and during machining.

To melt brass, the alloy must be heated to 880 - 950 degrees. Exactly what temperature is required for melting a particular type of brass depends on its composition, but when melting metals at home, it is not always possible to determine the grade of the alloy.

To guarantee melting of brass at home, you should purchase a special device in which the metal is heated to the maximum melting temperature.

Making a melting device yourself will require significant time and special knowledge. Therefore, it is much easier to purchase ready-made melting furnaces in specialized stores that run on gas or AC power.

Furnace and tools for melting brass

To cast brass at home, you need to purchase a special furnace.

At home, it is best to use small devices with a maximum heating temperature of 1300 degrees. Such a limitation is necessary to prevent burnout of the zinc contained in this copper alloy.

Graphite crucibles are used as a container for melting brass.
You will also need to purchase tongs and a large spoon. Tongs are needed to install and remove the crucible from the furnace, and a spoon is used to remove slag that forms on the surface of the melt.
A casting ladle is used to pour the molten brass from the crucible into the mold. Without this device, it is impossible to safely tilt the hot crucible during smelting operations.

Work with the melt must be carried out without any deviations from safety regulations, therefore, in addition to equipment for melting, you should definitely purchase protective clothing, eye and breathing protection.

When brass melts, harmful fumes are formed that negatively affect human health.

It is strictly prohibited to carry out smelting work without a respirator. Special glasses or a mask are used to protect the eyes from exposure to infrared radiation, which, with prolonged exposure, can cause damage to the organ of vision.
It is also necessary to use a heat-resistant apron to protect clothing from possible contact with molten metal and thick gloves to avoid burning your hands during melting work.

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When all the necessary tools and fixtures have been purchased, you can begin preparing to melt the brass.

Preparatory work

In order for the melting of a copper alloy to be carried out according to all the rules, it is necessary to prepare tools and a place for work.

The best option for placing a furnace for melting brass is a canopy in the fresh air. Installing a stove outdoors allows you to minimize the harmful effects of zinc vapor, as well as ensure good fuel combustion when using a gas stove.

In terms of fire safety, placing a high-temperature furnace outdoors is the most appropriate. If it is not possible to install the melting furnace in this way, then the room in which the melting work is planned to be carried out must be equipped with a forced air ventilation system.

The surface on which the stove is installed, regardless of its location, must be made of non-combustible materials. It is also recommended to install a box with dry sand to safely move the crucible with molten metal. To prevent splashing of molten metal, it is recommended to carry out mold pouring work only over a container with sand.

If scrap metal will be used to obtain the melt, then before starting melting, the brass surface should be thoroughly cleaned of dirt and paint.
When using rolled non-ferrous metal, it is enough to cut it into pieces, the size of which will not exceed the parameters of the crucible of the melting furnace.

Such preparatory work will allow for better melting of metal with less slag, and the process itself will be more fireproof.

Brass melting process

After the preparatory stage, you can begin to directly melt the copper alloy.

The work is carried out in the following sequence:

In the oven, the molds are heated to a temperature of +100 degrees. It is also necessary to warm the spoon well before use. This procedure is necessary to completely evaporate moisture from the surface of the instruments. After warming up, the molds must be placed on dry sand.
Pre-prepared brass scrap or crushed rolled metal for melting is placed in the crucible in the required quantity.
The oven heats up to a temperature of +500 degrees.
The crucible with brass is installed in the furnace and the temperature rises to 950 degrees.
When the metal has completely melted from its surface, you must carefully remove the resulting slag and oxidation products using a spoon.
When the brass acquires a bright yellow color, you can begin filling out the prepared forms. For this purpose, the crucible is removed from the furnace with special tongs and installed on a casting ladle. Then the molds are filled with melt.

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If it is necessary to continue melting the metal, the crucible must be filled again with the prepared material and installed in the melting furnace.

Tips and tricks

There are a large number of furnaces for melting metals on the market and it is not always possible to make the right choice of device. Especially if you have no experience in smelting. So that the furnace can be used not only for melting brass, it is recommended to choose a device with the ability to heat up to 1300 degrees. For example, the melting point of bronze is about 1150 degrees and low-power devices will not allow the melting of this non-ferrous alloy.
For each type of non-ferrous metal it is necessary to use a separate crucible, therefore it is not recommended to melt bronze or any other metal or alloy in a container in which brass was melted.
It is not recommended to wear synthetic clothing while performing smelting work. This fabric ignites and melts easily. In case of fire, may cause serious burns.
In the immediate vicinity of the place where the melting furnace will be installed, it is necessary to place a container with cold water. Such a protective measure will allow, in the event of a burn, to instantly reduce the temperature of the affected area of the body.
The fire extinguisher must be located in direct access to the place where smelting work is carried out.
The moment of complete melting of brass can be determined by eye. It is necessary to pour products from this alloy when the surface of the molten metal begins to glow yellow with a slight orange tint.
During melting, brass is strictly prohibited from stirring. This action can lead to the formation of air bubbles, which will negatively affect the density of the material, its mechanical and aesthetic properties.
The exact melting point of brass depends on its brand. When determining the melting point experimentally, care must be taken not to overheat the mixture so as not to accelerate the oxidation process of the metal alloy.
You can make a furnace for melting brass yourself, but only with special knowledge. If difficulties arise in this matter, you can seek advice from experienced craftsmen.

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Significant savings can also be achieved by replacing the graphite crucible with a ceramic product. If you purchase special refractory clay, you can learn how to make containers for melting furnaces yourself.

Ceramic crucibles have a significantly shorter lifespan, but in cases where it is possible to independently manufacture such parts, the money savings will be significant.

Conclusion

At what temperature copper and its alloys melt is described in the article, but theoretical knowledge alone is not enough to become a professional in this matter.

Once a brass melting furnace has been purchased or installed, it is necessary to melt a small amount of metal to test the functionality of the equipment. And gain experience in melting copper alloys at home.

Casting process

The process of casting bronze is extremely simple. The oven heats up to certain parameters. Let us remind you once again that to melt tin alloys it is necessary to heat the furnace to a temperature of 900–950°C; the melting temperature of tin-free alloys is an order of magnitude higher – 950–1080°C.

Melting of any bronze composition must begin with calcination of the mold for pouring in a muffle furnace or in a forge. To do this, the oven is first heated to a temperature of 600°C. Then the mold is immersed in it, after which the temperature in the oven must be increased to 900°C. The mold should spend a couple of hours in the oven. After the timer ends, the mold is removed from the oven and cooled to a temperature of 500°C.

The bronze is placed in a cast iron tray and sent straight into a well-heated oven. After the alloy has melted, the metal must be kept in the oven for another five minutes. This way it will warm up well, which means it will be easy to ensure high-quality filling of the casting mold. The crucible is removed from the furnace using a hook, and the process of pouring the molten alloy into the mold is ensured with tongs. It is important to pour the metal in a thin, continuous stream. This is the only way to prevent the process of blurring the shape.

How to properly pour molten bronze into a casting mold

Pouring molten bronze into a mold is a real science. Filling out a large form will be easy. The liquid alloy, under the influence of gravity and its own weight, will itself be evenly distributed throughout the container and displace all existing air. There will be a certain problem with filling out small forms. The fact is that air prevents the uniform redistribution of the alloy over all planes. Therefore, often melting bronze at home does not allow creating high-quality products.

Is it possible to solve a similar problem on my own? Yes, if you have a centrifuge at hand. Centrifugal force will displace the air and allow the alloy to be evenly redistributed over the entire area of the mold. It is necessary to act according to this plan very quickly, before the bronze has time to harden.

You need to remove the pouring from the mold when the alloy has completely hardened. The surface of the workpiece will be rough, and in some places metal deposits will definitely appear. Such defects are eliminated by mechanical grinding. If the oven has been heated correctly, the amount of mechanical grinding will be minimal.

Creating a casting mold

Given the fact that each type of bronze has its own melting point, it is important to have on hand a mold that can withstand the highest heating point of the alloy being described. It is difficult to create it with your own hands at home, but you can try if you carefully study the following instructions.

First you need to create a molding box (foundry workers call it a flask). Its dimensions are one and a half times larger than the dimensions of the future part. The flask is assembled from unplaned boards according to the following scheme: first, the upper frame is knocked down (outwardly it looks like an ordinary box without a bottom and top, but with two crossbars in the middle), then the lower frame (box with a bottom) is knocked down.

Then they begin to create the molding soil. It has a special composition: 75% fine-grained sand, 20% clay and 5% coal dust. All ingredients are combined and mixed thoroughly.

The next stage is making a model that will help form a mold for future casting. Experts recommend making it from wood. The further process is reproduced according to the following algorithm.

The wooden model is first generously sprinkled with talcum powder, and then carefully placed exactly halfway in the bottom drawer of the flask.
Then it is filled to the top with ready-made molding soil.
The entire resulting composition is generously sprinkled with graphite.
After this, the lower part of the flask (with a bottom) is covered with an upper frame (without a bottom).
A metal cone is inserted into the upper frame, the narrow part of which should touch the surface of the wooden model. The cone will allow you to form a sprue - a part through which molten bronze will be poured.
The top box is also filled to the top with molding soil. The filling is carefully compacted with a special mortar.
After this, the metal cone is carefully removed. Using a sharp knife, the upper flask is removed from the lower frame along with the molding sand. A wooden blank is removed from it. After all the manipulations performed, there should be indentations on both flasks that accurately copy the geometry of one half of the wooden model.

Note! At this stage, you can use a knife to correct slightly crumbling lines. If some of the earth sticks to the model, its deficiency in the flask is made up for. The excess is simply removed.

We leave the lower and upper parts of the flask until completely dry, and then connect them together so that there is no gap between them. The bronze casting mold is ready.

Using this form, it is possible to create bronze products that do not have a clear pattern and small details.

Processing Features

The home craftsman uses many different parts in everyday life that are made from brass.

In addition, quite a lot of different tools are produced that contain this component. Very often brass is found in an alloy based on bronze and copper.

Knowing the melting point of this metal, as well as the methods by which it can be melted, you can independently repair and manufacture some products that will be useful on the farm.

Melting this universal component based on bronze and copper has certain subtleties and nuances, knowing which you can avoid a variety of difficulties in your work.

Of course, in order to independently smelt this bronze-based metal, you must have certain knowledge in this area, as well as some tools that may be required in the work.

In addition, in order to melt brass yourself at home, you need to be patient.

To work, you should definitely have technical silver on hand, as well as a manual gas burner. You will also need a copper alloy and a special graphite torch.

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Borax should be purchased in sufficient quantity. In addition, in order to maximize the safety of the surrounding area for melting brass, you should purchase an asbestos sheet.

This process is quite labor-intensive and requires compliance with certain safety precautions.

If the brass alloy is based on copper or bronze, then when melting it is necessary to take into account certain subtleties, and also know some nuances that will help to carry out this work correctly and as efficiently as possible.

First of all, it should be taken into account that an alloy based on bronze and copper has slightly different melting parameters, and, accordingly, some characteristics of the metal, both physical and chemical, change.

Once all the necessary tools and materials have been prepared, you can proceed to melting brass with your own hands at home.

Casting brass into plaster molds - Metalworker's Guide

Gypsum hemihydrate CaSO4 mixed with the semianhydride substance γCaSO4 is used for castings from non-ferrous alloys, as well as for the manufacture of models and model plates; for small castings a mixture of 20% gypsum, 80% asbestos + water is made. The mechanism of strength formation is hydration (the more asbestos, the less water is taken).

For thin-walled castings with thin relief and a clean surface, instead of asbestos, fine-grained quartz powder is recommended; this mixture is stronger than cement and has low gas permeability, so it is melted in autoclaves at a pressure of 2 MPa for 8 hours, after which it is dried for 10-20 hours. To enhance gypsum mixtures, a surfactant can be introduced into them - this will allow, when foaming the gypsum slip, an increase in the number of gas bubbles, which, during the studied hardening of the mixture, promotes gas permeability.

This gypsum mold has microporosity and high gas permeability, which makes it possible to produce castings from alloys that release an increased amount of gases during hardening.

Chemical processes during hardening of gypsum mixtures

Hardening gypsum-water system

After mixing the gypsum mixture (its basis is anhydrous calcium sulfate, semihydrous gypsum and semianhydride) with water, solid hydrated calcium sulfate is formed in accordance with the equation

2 (CaSO4)• H2O+ 3H2O= 2 (CaSO4• 2H2O). (14)

The hardening time of gypsum depends on the grade of gypsum, the amount of water, the temperature of the water, and the dispersion of the gypsum. With a low water content, the mixture is poorly poured, hardens quickly, and releases an increased amount of heat, with a simultaneous increase in the amount of volume. The hardening time of gypsum increases with increasing water temperature, so cold water should be used.

Technological properties
of gypsum mixtures
With a sufficient amount of water, the gypsum mixture is mushy, quite fluid, hardens slowly and does not have a tendency to increase in volume. After the mixture hardens and the mold is heated before pouring, shrinkage occurs, which can cause cracking of plaster molds. The more water semi-aqueous gypsum contains, the greater its shrinkage when heated.

To reduce shrinkage, an increased amount of pulverized quartz, a minimal amount of gypsum and additives that cause expansion of the gypsum are introduced into the gypsum mixture.

The strength of dried gypsum mixtures increases with a decrease in the content of water and pulverized quartz. Mixtures of gypsum with quartz filler are relatively low-elastic, so forms made from them are deformed slightly. Quartz mixtures require less water than asbestos, since they absorb less of it. The linear shrinkage of such mixtures is also less than asbestos mixtures.

Advantages of gypsum mixtures:

— Satisfactory strength

- easy knockout

Flaws:

- insufficient heat resistance

- limited scope

— the presence of shrinkage of the mixture and possible cracking of the molds. To reduce cracking, pulverized quartz is introduced and the amount of gypsum is reduced.

Casting in ethyl silicate molds

Ceramic molds are used in the production of investment castings or the Shaw process. The molding mixture has a mushy consistency and consists of a solid ceramic component and a liquid binder.

The following refractory fillers are used for ceramic molds:

dusty quartz (marshallite) PC1, PC2, PC3. For ceramic molds PK2, PK3.
electrocorundum Used for refractory Me and Mg-based alloys.
zircon flour
titanium dioxide. Used for high-alloy steels and other alloys with a basic oxide nature.

Most often, silica SiO2 is used for ceramic forms in the form of dusted quartz (marshallite). As noted above, quartz, due to changes in its crystalline modifications, is characterized by a sharp change in volume when heated and melts at a temperature of 1550°C.

In addition to quartz, the following is used in the manufacture of ceramic molds:

Alumina

A12O3 - artificial corundum - is used in the form of powder and crumbs, the melting point is 2045 ° Q when heated, no significant volumetric changes occur.

Silimanite

А12О3• SiO2—natural aluminum silicate—suitable for precision casting of non-ferrous alloys; melts at a temperature of 1545° C.

mullite

3A12O3• 2SiO2—aluminum silicate obtained artificially from kaolin; melts at a temperature of 1810°C.

Zircon

ZrSiO4—zirconium silicate; melting temperature up to 2430° C.

Molochit

is calcined kaolin, which, in addition to SiO2 and Al2O3, contains oxides of titanium, iron and alkali metals.

The following is used as a liquid binder:

Alcosols,

or
hydrosols
, which are colloidal solutions of certain organic silicon compounds.
Among them, the most important is tetraethyl orthosilicate,
the chemical formula of which is SiO4 (C2H5)4. The connection of individual filler grains is ensured by a gel film formed under the action of water and an acidic hydrolyzed catalyst.

Heterosiloxanes

are aluminosilicate esters, which, under the influence of moisture contained in the air, hydrolytically split into colloidal solutions of aluminum and silicon compounds. The resulting gel after firing binds the ceramic grains in the form of strong aluminosilicates.

-Chloro-ethoxytitanate

used in benzene solution as a binder for alloys of titanium and other metals with high reactivity.

Aminoalkyl silicate

and
basic aluminum nitrate
are used in the form of alcohol solutions, the hydrolysis and gelation of which are caused by ammonia.

The mushy molding mixture is applied to the model in several layers, sprinkled with ceramic chips and dried. After removing or melting the model, a ceramic mold is formed. Drying is carried out slowly by raising the heating temperature to 120 ° C for several hours.

After removing the remaining carbon compounds and strengthening the silicate gel, the molds are sequentially fired at temperatures of 400, 600, 800, 1000 ° C for 6-8 hours. The molds are poured with metal immediately after firing, until they absorb moisture from the air.

As already indicated, in quartz materials, upon cooling, reverse recrystallization occurs, which can cause cracking of the forms.

Copper casting

Copper is one of the first metals mastered by mankind.

Copper

Thanks to its low melting point and high plasticity, it has not lost its popularity for the fifth millennium. Red metal is widely used both in industry and at home to make jewelry, crafts and parts by casting copper.

In industrial settings, technologies such as

Copper casting

Casting copper into molds
Powder metallurgy
Electroplating
Hot and cold rolled
Sheet stamping
Wire drawing
Mechanical restoration

They require complex and expensive professional equipment, highly qualified personnel and are accompanied by high energy costs.

Wire drawing of copper

At home, in a small workshop, simple technologies are used, largely repeating the work techniques of the Copper Age masters. This includes copper casting and wire drawing, as well as forging and embossing. Despite the simplicity and antiquity of technological techniques, home craftsmen achieve high quality products. Sufficient casting accuracy is ensured by careful production of the mold.

Characteristics of copper

Copper is a metal with a relatively low melting point (1083C), a density of 8 g/cm3 and high ductility. It occurs in nature in the form of nuggets.

Thanks to these qualities, it became the first metal mastered by mankind. Archaeologists have found tools and weapons in burials dating back to the 3rd millennium BC.

Most likely, humanity mastered copper casting even earlier, at the end of the Stone Age.

Basic properties of metals of the copper subgroup

The Latin name of the metal, Cuprum, is associated with the name of the island of Cyprus, a famous ancient center for the production of bronze products. Copper-based alloys - bronze and brass - have high strength and are less susceptible to oxidation. Bronze was widely used as the main metal of mankind until the development of mass steel production technologies.

Copper has excellent electrical and thermal conductivity. This leads to its widespread use in electrical and thermal engineering.

In addition, copper has pronounced bactericidal properties.

Copper smelting and casting equipment

Casting copper at home does not require particularly complex or expensive equipment. Buying it or making it yourself is quite within the capabilities of a home craftsman.

Required

Crucibles are cylindrical open vessels.

Examples of graphite crucibles

Steel tongs for removing and placing the crucible in the furnace.
Muffle furnace or gas burner.
Steel hook for removing oxide crust from the surface of the melt.
Casting mold.

First of all, you need to melt the copper. The better the feedstock is crushed, the faster the melting will occur. Melting will occur in a crucible made of ceramic or refractory clay.

The muffle furnace must be equipped with a thermometer and a glass window for visual inspection.

Electronic temperature control and maintenance system will make copper casting easier and provide better casting quality.

Molds for copper casting are made based on the model. Depending on the chosen technology, the molds can be disposable (from a mixture specially molded in the formwork) or reusable - steel molds. Recently, molds made from high-temperature silicone have become widespread.

At home, disposable forms are more often used. The model is made from wax or special types of plasticine. The model completely repeats the spatial configuration of the future product. When a hot melt is poured into a mold, the wax melts and is replaced by metal, which takes its place and repeats all the details of the mold's relief. This form is called lost wax.

Burnout mold for copper casting

There are also burnt forms. They use a model made of flammable material, such as papier-mâché. In this case, the model burns when a high-temperature melt is poured, the combustion products in the form of gases exit through the filling hole.

Main characteristics of the alloy

Paradoxically, brass itself and the method of its manufacture were known long before the discovery of zinc as a separate metal.
The ancient peoples of the Southern Black Sea region made copper-based alloys with the addition of a substance called galmey, or zinc spar. Very often, products from this combination were used as fake jewelry, which were passed off as gold. In ancient Rome, because of this, brass was called orichalcum, that is, gold-copper. It was used there for minting coins .

The physical parameters of the alloy look like this:

The specific heat capacity is 0.377 kilojoules per kilogram kelvin at room temperature.
The specific heat of fusion of brass is 210 Joules per kilogram.
The melting point is highly dependent on the content of alloying metals and varies from 850 to 950 degrees Celsius.
Density is about eight and a half tons per cubic meter.
Resistance per unit length is within 0.07 microohms.

As you can see, brass melts much easier than copper, and therefore is well suited for the manufacture of decorative elements and objects of art, even without the help of specialists.

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Brass grades and applications

The brand of brass and its scope of application depend on the composition. For example, tombak, which belongs to the class of wrought brasses, which contains more than 95% copper, can easily combine with steel, forming a bimetal with it. This compound is used in the manufacture of insignia and various objects of art and interior design - figurines, frames, candlesticks .

LO grade brass is used for the manufacture of condenser tubes used in various heating equipment, for example, gas boilers, autoclaves, and bellows.

The LS brand is used to create parts for watch mechanisms, adapters and connecting bushings. Printing matrices are also made from it.

LMC - is found in old Soviet coins with denominations up to 5 kopecks, fittings, nuts and bolts, and its subtype with the prefix “A” is found in parts of river and sea vessels.

Brass, marked LA or LZhM (and its subtypes), is also used for the construction of sea ships and aircraft, various electrical machines and bearings. Very common in parts for various chemical equipment.

Metal characteristics

There are several varieties of brass materials available that have a wide range of applications. The most common metal compounds include:

multicomponent composition;
double made of zinc-copper alloy.

The melting point of brass depends on its components. In addition to industry, various interior items and parts of furniture structures are made from it. This became possible thanks to casting, which makes it possible to give the product any shape. Melting at home does not pose any particular problems if you have the appropriate knowledge and the necessary special equipment. To do this, you must know at what temperature this metal composition melts. It has a yellowish color, which without additional protection turns black when exposed to air.

The lower limit at which the brass composition melts is about 880 °C, and its upper value reaches 950 °C. To lower the melting point of brass, more zinc is added to it. The characteristics of the metal are negatively affected by bismuth or lead. Please note that the melting point of copper is different from brass. When the material is heated, they significantly reduce its ability to undergo plastic deformation.

Brass is capable of providing high resistance to corrosion, has increased fluidity and excellent anti-friction characteristics. Thanks to all these properties, it is actively used both in general industrial products and in highly specialized components. The surface of the composition is perfectly polished, which allows it to maintain its magnificent appearance for a long time. Brass and bronze have different melting points, which is taken into account when choosing the operating mode.

Melting point of brass

What is brass? It is a copper-based metal alloy. The main alloying component is zinc, but if necessary it can be replaced with manganese, iron, nickel or lead. That is why the industry produces several grades of alloy.

The most popular of them are two: two-component (contains only copper and zinc) and multi-component brass (in addition to copper and zinc, there are several alloying elements). Each brand has its own temperature limit, which allows you to transform solid metal into a liquid state.

This article will tell you what the melting temperature of brass should be, how you can melt the metal at home, what you need to pay attention to if you want to comply with all the technological features of the process.

How to melt brass at home?

Experts know that brass melts at a temperature range of 880-950 degrees Celsius (much lower than that of bronze).

Therefore, it is important to purchase a furnace that will melt the alloy before the other components of the metal oxidize.

If experiments with alloys cease to be just a hobby, it is advisable to purchase and install furnaces that can heat up to 1100 degrees and higher. Then the process of melting bronze and other non-ferrous metals will be available.

In addition to the oven, you will need a special set of tools for the job. You need to purchase a graphite crucible - a container in which brass, cut into pieces, will be melted, and then melt it in a furnace.

Each crucible is best used for a specific metal alloy (a crucible for bronze cannot then be used for melting brass). The new crucible is pre-hardened, only after which it becomes suitable for melting non-ferrous metals.

This is done simply: the oven is heated to a temperature of 95 degrees, the melting container is immersed in it, and left there for about twenty minutes. After this, the crucible should cool down.

The crucible is immersed in and removed from the furnace using steel tongs. You should also have a large spoon at hand. It will help remove slag from the surface of the liquid metal. A foundry ladle is a device used to hold a crucible and tilt it in order to pour liquid brass into a mold.

Before placing the alloy in the firebox, it is important to clean the brass, wash the metal with soap, and use it to remove contamination in the form of oil stains and oxidation products. If the products selected for remelting are varnished, it is better to remove its layer with a special chemical composition (varnish thinner, for example).

Note! You need to remove the varnish outside or in a well-ventilated area. It is better to protect your hands with gloves.

The stove is installed in a well-ventilated area; experts recommend simply placing it outside under a canopy. When heating any metal (including brass and bronze), toxins and carbon dioxide enter the air; the furnace itself works more efficiently in the presence of a large amount of air. Therefore, the street is the best place to install the described equipment.

It is important to install a sandbox next to the stove. It is a necessary part of ensuring the safety of this type of work. Only over a box of dry sand can liquid brass be transferred and poured into the mold. If a drop of liquid metal (including bronze) comes into contact with droplets of moisture, the water will instantly turn into steam and spray the hot metal.

Where smelting equipment is sold, special clothing attributes are also sold that help protect a person both during smelting bronze and during smelting brass. These are gloves made of durable leather, high boots and a heat-resistant apron. They must be worn over cotton clothing with long sleeves and long pants. They will protect the skin from accidental drops of hot metal.

Note! Under no circumstances should you wear synthetics before melting metal. This material catches fire quickly and burns for a long time; in the event of force majeure, synthetics will aggravate the situation.

The last piece of equipment is a protective mask (or goggles) on the face, as well as a respirator with a P100 filter. Without it, brass cannot be melted. Component additives have a lower melting point than copper. Therefore, before the brass melts, all impurities will burn, releasing acrid smoke. It gets into the lungs when you breathe. The consequences can be dangerous to human health.

Detailed melting algorithm

Heat the molds in the oven to 100 degrees Celsius. Such an operation will get rid of moisture that can cause metal to splash. For the same reason, it is important to burn through the spoon. Hot parts should be placed in a box with sand.
Place the brass in the crucible.
Preheat the oven to half the required temperature (melting point).
Place the crucible in the furnace body. And raise the temperature to 930 degrees. If necessary, the temperature can be increased by 30 degrees. The choice of heating mode depends on the type of brass selected. An experienced specialist is able to determine by eye whether the metal is ready for pouring. It glows yellow with an orange tint, its color becoming indistinguishable in daylight.

Note! Increasing the temperature above the melting current of brass will help to significantly speed up the smelting process, but such an action can provoke oxidation of the metal.

After the brass melts in the oven, you need to remove oxidation products from its surface with a spoon. Under no circumstances should the composition itself be mixed. It is important to proceed with caution. The main thing is to prevent the formation of air bubbles in the alloy. They will not allow you to pour out a quality mold.
When the brass is completely melted, it can be removed from the oven. The crucible is picked up with steel tongs and carefully placed on the casting ladle. After this operation it will be easy to pour the liquid metal from the crucible into the mold. To prevent the furnace from cooling down, you need to put a new portion of brass in the crucible and send it to the brazier.

Melting brass is a dangerous process; be sure to have a fire extinguisher on hand. Experts recommend that all beginners first train and melt small portions of metal and only then master large volumes.

A furnace for melting can be bought in a specialized store, but if necessary, you can assemble it yourself, but this can only be done in the presence of an experienced stove maker.

During the smelting process of brass, gases (zinc oxide) that are dangerous to humans are released, which is why it is so important to follow all the rules of safe equipment.

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Manufacturing methods and characteristics

Physical data

The characteristics of the alloy are determined by its chemical composition and can vary within certain limits. Bronze is less susceptible to corrosion and provides better metal-to-metal glide than brass. It has higher strength and is less susceptible to atmospheric influences (water and air) and better resists salts and organic acids. It is easy to machine, it can be soldered and fastened by welding. Some physical characteristics of bronze:

specific gravity from 7.8 to 8.7 tons/cu.m. meter;
melting point of bronze – melts when heated from 930 to 1140 degrees;
color changes from red - the color of copper, to white - the color of tin;
wear resistance and good sliding on metal determine the scope of application as sliding bearings; they work well in any temperature conditions;
There is high electrical conductivity and heat transfer, resistance to steam, which contributes to the manufacture of parts for equipment operating in extreme situations.

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How to make bronze

Melting and mixing copper melts and additives of different metals, which make it possible to give the alloy certain required characteristics, leads to the production of an alloy metal such as bronze. The manufacturing process involves electric induction furnaces and crucible forges; with their help, any alloys with copper can be produced.

Melting is carried out with flux additives, and the initial raw material for smelting can be either copper ore or copper scrap. Typically, scrap copper is added to the melt along with the filler metal during the smelting process. When smelting only copper ore, the following operations are performed:

the furnace is heated, copper ore with flux additives is placed in it, and melted at a temperature of about 1200 degrees;
a chemical oxidizer is added - phosphorous copper, half could be loaded as part of the flux, and the rest is additionally loaded with a ladle;
during melting, filler metals are added to the deoxidized molten copper, preheated to one hundred degrees;
After settling the melt for half an hour, the floating slag is removed from its surface, and the resulting alloy is distributed into molds.

When using scrap copper, the procedure for making bronze is the same.

Where is brass used?

A non-ferrous metal such as brass is an alloy of copper and zinc (up to 50%) with possible impurities of a small amount of alloying elements. It has high thermal and electrical conductivity, density in the range of 8300-8800 kg/m3 and strength up to 600 MN/m2. Due to these qualities, as well as its attractive golden yellow color, brass is widely used:

In art. Figurines and busts of famous figures are often made from this material, as it responds well to high temperatures. In addition, in the search for ideal forms, the finished sculpture can always be melted down.
In interior and exterior design. Stylish light fixtures, mirror frames, and copper and zinc alloy countertops create a 1970s and mid-century modern feel while serving utilitarian functions. To prevent the alloy from blackening when exposed to air, the products are coated with protective compounds.
In industry. The alloy of copper and zinc has a low coefficient of friction, so it is often used to cover the rubbing surfaces of bearings and other parts, and to produce mechanisms for land and water transport, fittings, etc.

brass products
In construction. Bronze and brass are resistant to corrosion, so products made from them can be used in conditions of high humidity. Shut-off and balancing brass fittings are common when installing water pipelines.

Casting brass into plaster molds

This gypsum mold has microporosity and high gas permeability, which makes it possible to produce castings from alloys that release an increased amount of gases during hardening.