Induction crucible melting furnaces. Induction furnaces for melting metals: types, principle of operation and technology of use

Attach the outer cylinder to the metal bottom. This can be done by welding or screwing. If the size of the bottom is significantly larger than the diameter of the cylinder, this will make the structure more stable and safe.

Place the bottom of the outer cylinder on fire bricks, making sure it is as stable as possible. These heat-resistant bricks will support your furnace during melting and insulate its hot bottom.

Insert the inner cylinder into the outer one, making sure it fits exactly in the middle. The space between the cylinder walls can be filled with fireproof lime mortar or dry sand, which will give the structure a O greater stability; you can simply fix the cylinders relative to each other with metal wedges.

Drill or cut a hole about 6 cm (2 1/4 inches) in diameter in the outer and inner cylinders near the bottom, slanting inward and upward, so that air can flow freely into the crucible, providing oxygen to the burning fuel.

Cut a metal tube with a diameter of 6 cm and a length of half a meter or more (a thin-walled metal tube for wires will do) - it will serve to supply air to the melting chamber; weld it to the hole in the outer cylinder or attach it with screws.

Cut the circle sheet metal, large enough to completely cover the top of the camera. Cut a 15X15 cm (6X6 inch) hole in this circle to allow air to circulate freely and to add metal to the crucible; the cut piece will serve as a lid. For convenience, you can attach the lid with a chain to the outer wall of the oven, and also attach a handle to the lid.

Make a crucible (melting pot). You can use a suitable metal cylinder from an old thermos, or a cauldron made from of stainless steel. In order to be able to pour molten metal from the crucible, attach a steel handle to it, which would protrude from the top of the melting chamber.

Connect the blower to metal tube, previously built near the bottom of the housing. Can be used old hair dryer or a low-power leaf blower, attaching them to the tube with tape. If you have neither a hairdryer nor a machine, any device that will provide the necessary air flow through the tube. However, remember that too much air flow can lead to intense and rapid combustion of coal, and insufficient air flow will suppress combustion and will not provide you with the required temperature.

You will need

• Crucible
• Crucible tongs
• Muffle furnace
• Charcoal
• Household vacuum cleaner
• Steel wire hook
• Form

Instructions

Video on the topic

note

Helpful advice

Sources:

• copper melting point

If you need to melt metal for any purpose, you will encounter a number of problems that you can solve and still complete this procedure with my own hands. For example, it is not as difficult to melt as many other materials. And if you want, it’s quite possible to do it yourself.

Instructions

Find a way to achieve temperatures greater than 1083 degrees Celsius. This is necessary in order to copper started Don't believe stories about how people were able to melt copper on a fire in a tin can or a piece of copper wire on a spoon, using only a lighter. Even if they are real, one conclusion can be drawn - it was not copper.

You can use a blast furnace if it is available where you live or if you have the opportunity to use it. Before renting a stove, make sure that it can heat up to the temperature you need and that it has the ability to adjust the heat, as you cannot copper began to boil. You need to be able to balance between temperature changes.

Try building a smelting furnace at home. You can make a melting furnace at home from scrap materials. Schemes of such furnaces are available on every specialized forum. The most common design is created from a used fire extinguisher. If you choose this option, then saw off the fire extinguisher head and attach a closing lid. Treat the inside with clay and install a melting pot, which can be purchased at specialized stores.

Remember that the mold into which the molten copper will be poured must have a higher melting point than the mold itself. copper.

Video on the topic

Copper items can be very beautiful, and it is tempting to make something copper yourself. To do this, the metal must be melted. In foundry, for the most part, three main varieties of this metal are used: pure red copper and its alloys: bronze and brass.

You will need

• Crucible
• Crucible tongs
• Muffle furnace
• Charcoal
• Household vacuum cleaner
• Steel wire hook
• Form

Instructions

Upon reaching desired temperature When the metal melts, open the door and grab the crucible with tongs. Move the oxide film to the side using a wire hook. Pour the melt into the prepared mold. If the muffle furnace is of sufficient power, it can be used to melt any alloys and copper.

If not muffle furnace, you can melt copper with an autogen, directing the flame from the bottom of the crucible upward. In this case, melting will occur with good access. To protect the metal from intense damage, it is recommended to sprinkle its surface with a layer of crushed charcoal.

If you have neither an autogen nor a blowtorch, you can use a simple forge. In this case, place the crucible on a layer of charcoal. To increase the combustion temperature of coal, use forced air injection into the combustion zone. Suitable for this household vacuum cleaner, working on blowing. The vacuum cleaner hose must have a metal tip. The tip hole can be narrowed to produce a thinner stream of air.

Video on the topic

note

The muffle furnace should allow the following temperatures to be obtained: for melting copper – 1083°C, for melting bronze – 930-1140°C, for melting brass – 880-950°C.

Red copper is viscous. It is of little use for thin castings. Brass is more suitable for these purposes. The lighter the brass, the more fusible it is.

The forge is an open furnace with a hood in which charcoal is burned. To increase the temperature, additional air is blown into the forge using bellows or a compressor.

Helpful advice

Clay and ceramic crucibles are used to melt copper.

Instead of a forge, you can use an autogen or a blowtorch.

Sources:

• copper melting point

To melt copper, as with any other metal, it is better to use special equipment and work under the guidance of a master. But if circumstances forced you to start melting metal at home, then make a special melting furnace.

Instructions

Make two holes (locking holes) at both ends of the pipe to attach the nichrome thread. The nichrome thread is a heating element; it must be attached together with a piece that will protect the turns of the wire during winding.

Using the formula L=RxS, calculate the length of the thread, where the resistance heating element heating –R, S - wire cross-section (nichrome); resistivity nichrome –p and equal to 1.2; the required length is L.

Wind the wire together with the cord in the form of a spiral and coat it liquid glass. Then remove the conductor and wrap the spiral with asbestos.

Make a temperature sensor. Take chromel and alumel wire and twist them together. Attach the wire coming from the transformer (latr) to one end of the twist. Set the transformer regulator to zero division.

On the left is the temperature sensor. 1). transformer (latr), 2).first contact on the clamp, 3). from the latr the second contact, 4.5). chromel and alumel wire, 6). a cup made of a substance that is current, 7). (mixture) of borax and graphite, 8). twisting two wires (soldered).

Apply current for a few seconds. A ball of melt should appear at the contact site. Working part thermocouples are mounted in the furnace lid and connected to a millivolt, which is rated at 500 millivolts.

Re-calibrate the scale; the point of different metals can serve as a guide. Carry out this operation already in finished oven. Make the top cover of the oven and the bottom from clay (fireclay). The oven can be equipped with a viewing window made of special glass.

1) asbestos thermal insulation 2). made of clay, 3). nichrome spiral, 4). cover (top), 5). output of nichrome thread (wire), 6). thermocouples, 7). millivoltmeter, 8) under. If the charge will be loaded directly into the furnace itself, and not into crucibles, then coat the inside of the furnace with graphite paste. Mix the paste in liquid. When working with such an oven, follow safety precautions.

Before metal is embodied in a specific product, it must go through a long journey. And it all starts with an inconspicuous piece of rock discovered by geologists. Metal-containing minerals consist of ore matter and waste rock. After the beneficiation process, the ore is sent for smelting.

Instructions

Cast iron is obtained from four types of iron ores - brown, spar and magnetic iron ore, which are different percentages from each other. Pig iron is smelted in huge blast furnaces with the addition of manganese.
First, load coke into it, then add agglomerate and coke in layers. Sinter is a specially prepared ore sintered with flux. Melting cast iron by blowing heated air and oxygen into the furnace, creating the temperature necessary for this. In particular, feed into the ring pipe surrounding bottom part furnace, and from there through tubes through special holes in the forge - tuyeres - into the forge.

In the forge, coke is burned to form CO2, which then rises through layers of hot coke and, interacting with it, forms CO– carbon. It restores a significant part of the ore, again turning into CO2. Remember that ore recovery occurs primarily at the top of the mine.

In order to get rid of unnecessary impurities, use flux, which turns them into slag. During the reduction process, the ore becomes solid. By going down into the steam - the hotter part of the furnace - the iron mixes with carbon, resulting in cast iron.

A homemade melting furnace can be made of graphite, cement, mica or tiles. The dimensions of the furnace depend on the power supply and the transformer output voltage.

The homemade melting furnace heats up gradually, but reaches significant heat. For this design, it is necessary to install a voltage of 25 V on the electrodes. If an industrial transformer is used in the design, then the distance between the electrodes should be 160-180 mm.

The process of making a homemade melting furnace

You can make a melting furnace with your own hands. Its dimensions will be 100x65x50 mm. In this design you can melt 70-80 g of silver or other metal. Such possibilities for a homemade melting device are very good.

Materials and tools:

• brushes from a high power electric motor;
• graphite;
• electrode rods used in arc melting furnaces;
• copper wire;
• nails;
• mica;
• cement tiles;
• brick;
• metal pan;
• carbon graphite powder;
• fine conductive wire;
• transformer;
• file.

To make a melting furnace with your own hands, you can use brushes from a high-power electric motor for the electrodes. They have excellent current carrying wire.

If you cannot purchase such brushes, you can make them yourself from a piece of graphite. You can use an electrode rod, which is used in arc melting furnaces.

On the sides of this rod, you need to make 2 holes with a diameter of 5 mm, then, to add strength, carefully hammer a nail of suitable size into it. To improve contact with graphite powder, using a file, it is necessary to make a mesh notch on the inner surface of these electrodes.

Mica is used to make the inner surface of the stove walls. It has a layered structure and therefore can be used as a good heat-insulating screen.

The outside surface of the structure must be covered with cement or asbestos tiles, which have a thickness of 6-8 mm. After installing the walls, they must be tied with copper wire.

A brick should be used as an insulating stand for the device. A metal tray is installed underneath. It should be enameled and have sides on the sides.

Then you need to make carbon graphite powder. It can be prepared from unnecessary rods. It is better to do the work with a file or hacksaw for metal.

When using a stove, graphite powder gradually burns out, so it needs to be topped up occasionally.

To operate the device, a step-down transformer with a voltage of 25 V is used.

In this case, the network winding of the transformer must have 620 turns copper wire, which has a diameter of 1 mm. In turn, the step-down winding should have 70 turns of copper wire. This wire must be fiberglass insulated and rectangular section dimensions 4.2x2.8 mm.

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How to make a transformer?

If you cannot buy a transformer that has enough high power, it can be made from several similar transformers with lower power. They must be designed for the same network voltage.

For this purpose, it is necessary to connect the output windings of these transformers in parallel.

Can be made. To do this, you need to prepare L-shaped metal plates with an internal cross-section of 60x32 mm. The network winding of such a transformer is made of enameled wire with a cross-section of 1 mm. It should have 620 turns. In this case, the step-down winding is made of wire having a rectangular cross-section with dimensions of 4.2x2.8 mm. It should have 70 turns.

After installing the furnace, it is connected to the transformer using a copper wire having a thickness of 7-8 mm. The wire must have external insulation so that a short circuit does not occur during operation of the oven.

When the oven is completely ready for use, it must be warmed up well. In this case, the organic substances in the structure should burn out. During this procedure, the room should be well ventilated.

The device will work without soot. After this, the operation of the furnace is checked. If everything works fine, then you can start operating the device.

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How is metal melted in a furnace?

Metal melting is performed as follows. Using a small spatula (in the center of the stove), you need to make a small hole in the graphite powder, put scrap metal there and bury it.

If the pieces of metal to be melted have different sizes, then first of all lay a large piece. After it melts, add small pieces.

In order to check whether the metal has already melted, you can rock the unit a little. If the powder ripples, it means the metal has melted.

After this, you need to wait until the workpiece has cooled, then turn it over to the other side and melt it again.

This procedure must be repeated several times until the metal takes the shape of a ball. In this case, it is considered that the melting of the metal was performed with high quality.

If you need to melt sawdust or metal shavings of inexpensive metals, you need to pour them into the powder well and perform normal melting.

More expensive or precious metals should be placed in a glass ampoule from under medicines and melt together with this ampoule. In this case, a film of glass is formed on the surface of the molten metal, which can be easily removed by placing it in water.

Metals that melt easily should be placed in iron containers. If it is necessary to make an alloy of various metals, then the metal that melts less readily is put into the furnace first. After it melts, add fusible. For example, to obtain an alloy of copper and tin, you must first put copper into the powder, and then tin. To obtain an alloy of copper and aluminum, first copper is smelted, and then aluminum.

This device can melt metals such as tin, iron, copper, aluminum, nickel, silver, and gold. After melting the metal, it is forged. It is forged on an anvil using a hammer. In this case, it is necessary to frequently heat the workpiece on a fire until red-hot, and then hammer it again. After this, the metal is placed in cold water, and then processed again with a hammer until the workpiece acquires the required dimensions.

Under no circumstances should metals such as lead, magnesium, zinc, cadmium, cupronickel be melted, since when they burn out, they form very toxic yellow smoke, which has a detrimental effect on human health. You cannot melt silver contacts from relays and other devices because they contain up to 50% cadmium.

The muffle furnace is a specialized design that allows heat various metals to the required temperature.

The muffle has the property of keeping metal from direct contact with fuel or gases. Furnaces with a stationary heating chamber and replaceable muffles operate on a similar principle.

Methods for hardening metal

There are several ways to process metals using of this device:

• Heat treatment: annealing, hardening, tempering, aging.
• Working with valuable materials, melting of metals when the use of open fire is unacceptable.
• For getting even surface tone, especially when processing ceramics (highly artistic), a muffle furnace is used.
• Drying dielectrics.
• Cremation, combustion to mineral components.

How does a muffle furnace work?

In order to understand how a device for hardening metal works, the process of interaction of various elements occurs, let us carefully consider its structure:

• Furnace body. If you still have an old gas stove with a built-in oven, then it is perfect for the base of the device. Best size for such oven: 70cm-50cm-60cm. These dimensions are convenient for working with heat treatment.

Attention! If you decide to use a former gas stove as the main structure, then make dismantling plastic components. Otherwise, all materials will melt.

• Inner layer. Direct contact with the surface of the firebox. The efficiency depends on this part of the structure, so refractory fireclay bricks should be used.

Photo 1. Refractory fireclay brick is a mandatory element for the inner layer when making a stove with your own hands.

• Outer layer. Its purpose is to reduce heat transfer losses. Widely used overflow and basalt wool to achieve effect.

Advice! Do not use asbestos as an outer layer. When heated, this material releases carcinogens.

• Heating the workspace. Spirals made from nichrome or fechral wire are responsible for the heating process of the entire gas stove. It is better to use fechral ones, as they are more flexible, but nichrome ones are cheaper.

Aluminum and copper melting device

Low-melting metals are brittle. It is important to follow the work schedule with this type of metal.

So, for example, to melt copper or aluminum, the muffle furnace must be heated up to 1083, and for melting bronze - 930 Celsius.

These materials have the highest melting points among other fusible materials.

This means that the conclusion suggests itself: to work with low-melting metals, you need a furnace that heats up to a maximum up to 1100 degrees.

Nuance! For large castings when working with low-melting metals, a forge is installed. Can you melt metal? in a container with a spout(crucible). This way it is easiest to give it a form later.

Stages of working with low-melting materials

1. Calcination of the furnace for pouring at temperature 600 degrees.
2. Immersion of form.
3. Heating temperature to 900 degrees.
4. We record the time the mold remains in the oven - 120 minutes.
5. Remove the mold and cool until 500 degrees.
6. The low-melting material is placed in a mold.

Melting gold

Refractory metals, such as gold, have a high melting point when working. So, to successfully solve the problem, it will be necessary preheat oven to 1300 degrees, provided that we are working with steel (for other materials we need to look at the refractoriness coefficient).

Should be considered factor of kindling materials. So, you can heat the stove with all unnecessary household materials, excluding toxic ones, that is, those that release toxic substances during the combustion process.

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Stages of working with refractory materials

DIY induction muffle furnace

Muffle furnaces are a design necessary for the creativity of jewelers, blacksmiths, other craftsmen working with ceramics and steel hardening. Typically, an induction muffle furnace for melting is expensive, but it is possible to make it yourself.

Required materials and tools

Manufacturing of the structure

• Installation of the main part. On internal sides We cut out transverse holes using fireclay bricks. They are used to install the heating coil. Such grooves increase the volume of the oven, that is, the internal space with which it is more efficient to work. We fold the bricks and fix them in the shape of a prism. We eliminate the gaps.​
• Manufacturing of walls. Materials used: kanthal, fechral, ​​nichrome. You can install the materials in absolutely any way, but it is better to fold them in a circle. Thus, there will be no temperature differences that negatively affect the heat treatment process.

Photo 2. The main part of the muffle furnace is assembled from fireclay bricks, in which holes are cut out.

• Installation of thermal insulation. Efficiency depends on the degree of temperature retention within the structure. The thermal insulation itself is a mixture consisting of 0.8 parts cement and 0.2 parts perlite. The mixture between the prism and the walls should sit for about 48 hours.
• Making the bottom. We create a curved blank for the bottom of the product, attach four small pieces steel pipe- these are the legs on which the stove will rest. Pour inside the product cement mixture, after hardening, we apply wire in the form of a mesh to create an even and one-dimensional layer. At the end we apply talc.
• Making the lid. We create a blank of the same size as the bottom and attach handles to it. We fill the lid with a solution of cement and overflow.
• Making a spiral. Nichrome wire with a cross section of 0.1 cm and an iron rod with a radius 3 mm. After removing the wire from the rod, we get a spiral. The turns should not touch. The finished spiral is placed in the slots made at the first stages of production.

Photo 3. Spiral from nichrome wire placed in special slots in refractory bricks so that the coils do not touch.

Jewelry and other items made of copper or with copper elements have become widespread throughout the world. Finding it at home, in scrap metal, will not be difficult. There are many applications for this metal. Often, in order to achieve the goal, it is necessary to melt copper, and do it at home. The procedure is quite simple if you know its characteristics and melting point.

Characteristics

Copper is one of the first metals that people began to obtain and use for further processing. Products made from an alloy or pure copper were used even before our era. This demand arose as a result of easy processing conventional methods, as well as ease of melting and casting.

The material has a characteristic red-yellow tint, and due to its softness, it can be easily deformed, melted, processed and made various items. When the surface comes into contact with oxygen, it begins to form an oxide film, which gives a beautiful shade.

Very significant characteristic– electrical and thermal conductivity of the material, which has the second place among all types of metals, silver is in first place. These characteristics made it possible to use it in the electrical field, as well as for rapid heat removal.

Melting temperature

Melting is the process by which a metal changes from a solid to a liquid state. Each material has its own melting point, at which a liquid state can be obtained. The presence of impurities plays a major role in smelting.

The metal itself begins to melt at 1083 degrees. If the composition contains tin, then the temperature is reduced and will range from 930 to 1140 degrees. Such a temperature difference is precisely due to the presence of tin in the composition. If zinc is included, then the alloy can be melted in temperature range 900-1050 degrees.

This metal can boil at a relatively low temperature for metals. It is 2560 degrees, during boiling the process will be similar to other liquids in this state. The casting begins to bubble and gas is released.

To know how to melt material at home, you need to study step by step instructions And various options procedures described below.

Step-by-step instructions for melting

To melt copper at home, you need to make the temperature a little higher than the one at which it will melt. In this case, it will not be possible to use a jar and a fire or similar methods. There will be no result.

It is recommended to use a blast furnace, and it is important that the heat be regulated. You can make a smelting furnace with your own hands from ordinary materials. The exact diagram and principle of operation can be used on various forums, watch the video with step-by-step instructions.

Old fire extinguishers are often used to create a stove. If you choose this method, you need to cut top part and make a lid that will close. Additionally, the interior space is treated with clay and a heating element is installed.

Smelting should be carried out in a container that will not itself be damaged. high temperature melt and deform, respectively, capable of withstanding more than 1100 degrees. Additionally, remelting copper products requires the creation of a nitrogen environment; if it is not there, the material will deteriorate.

When everything is ready, you can melt the material and get a single ingot from it, which can be used in the future for your needs.

Melting in a muffle furnace

You can melt copper at home using the following equipment:

• The crucible into which the metal will be placed for melting.
• Tongs that can remove the crucible from the furnace.
• Muffle furnace or forge for heating.
• Mold for pouring liquid copper.
• Steel hook.

The step-by-step casting algorithm is as follows:

1. The metal for smelting must be crushed and placed in a crucible. The finer the state, the faster the material will melt. The finished crucible is placed in a furnace heated to the required temperature.
2. When the copper becomes liquid and completely melts, you need to remove the crucible with tongs, and you need to act carefully but quickly. There will be chaff on the surface of the liquid mass; use a hook to move it and pour the material into the prepared container.
3. It is not recommended to use pure metal to create complex figures or small objects, this is caused by the poor fluidity of copper without impurities. In this case, it is better to use alloys that contain zinc, tin and other metals.

Homemade devices

To smelt copper it is not necessary to use special devices; you can use homemade designs. The main condition is to comply with safety precautions and basic rules for working with the material.

If there is no muffle furnace or forge, then a simple gas burner is used. True, the copper itself will come into contact with oxygen, due to which rapid oxidation occurs. To prevent the appearance of a thick layer on the surface, you must use crushed coal when the metal takes a liquid form.

To obtain a liquid consistency of the material you need:

1. Place a support on the ground; for this purpose, use sand-lime bricks, a metal mesh with small cells is placed on them.
2. Coal is poured onto the grid and heated using gas lamp. To obtain a high temperature, you can use a vacuum cleaner that is aimed at the coal and produces a strong air flow.
3. A crucible is placed on the hot material, you need to wait until everything melts. Then pour the resulting liquid into the mold.

You can also use a propane-oxygen flame at home. It is recommended to use it for alloys containing tin or zinc.

If you have a powerful microwave oven at home, then you can carry out the melting procedure in it. For safety, as well as to preserve heat and protect the furnace itself, it is necessary to wrap the crucible in a heat-resistant material, and also use a cover for it. After placement it is necessary to put maximum mode and wait for the metal to melt.

Due to its low melting point, copper can be easily used to make various parts and objects right at home. Using the described methods, you can achieve high-quality results with minimal investment. As soon as the temperature drops, the material will begin to accept solid state and then it cools down completely. To create small or complex parts, alloys must be used.

During the work, it is recommended not to bring the material to a boil, since it loses its properties, becomes less hard after cooling, and deteriorates visually. As a result of boiling, gas is released, and after cooling the products will have a porous surface.