Induction heaters work on the principle of “generating current from magnetism”. In a special coil, a high-power alternating magnetic field is generated, which generates eddy currents in a closed conductor.

Closed conductor in induction cookers ah is a metal cookware that is heated by eddy electric currents. In general, the principle of operation of such devices is not complicated, and if you have a little knowledge in physics and electrics, assembling an induction heater with your own hands will not be difficult.

The following devices can be made independently:

1. Devices for heating in a heating boiler.
2. Mini ovens for melting metals.
3. Slabs for cooking food.

An induction cooker with your own hands must be made in compliance with all the rules and regulations for the operation of these devices. If an electromagnetic radiation hazardous to humans is emitted outside the body in lateral directions, then it is strictly prohibited to use such a device.

In addition, a great difficulty in designing a stove is the selection of material for the base of the hob, which must meet the following requirements:

1. Ideally conduct electromagnetic radiation.
2. Not conductive.
3. Withstand high temperature load.

In household cooking induction surfaces expensive ceramics are used, when making an induction cooker at home, it is quite difficult to find a worthy alternative to such a material. Therefore, to begin with, you should design something simpler, for example, an induction furnace for hardening metals.

Manufacturing instruction

Blueprints

Figure 1. Electrical diagram induction heating body
Figure 2. Device. Figure 3. Schematic diagram of a simple induction heater

To make a furnace, you will need the following materials and tools:

• solder;
• textolite board.
• mini drill.
• radioelements.
• thermal paste.
• chemical reagents for etching the board.

Additional materials and their features:

1. For making a coil, which will emit the alternating magnetic field necessary for heating, it is necessary to prepare a piece of copper tube with a diameter of 8 mm and a length of 800 mm.
2. Powerful power transistors are the most expensive part of a homemade induction machine. To install the frequency generator circuit, you need to prepare 2 such elements. For these purposes, transistors of the following brands are suitable: IRFP-150; IRFP-260; IRFP-460. In the manufacture of the circuit, 2 identical of the listed field-effect transistors are used.
3. For the manufacture of an oscillatory circuit you will need ceramic capacitors with a capacity of 0.1 mF and an operating voltage of 1600 V. In order for a high-power alternating current to form in the coil, 7 such capacitors are required.
4. When operating such an induction device, field-effect transistors will get very hot and if radiators made of aluminum alloy are not connected to them, then after a few seconds of operation at maximum power, these elements will fail. The transistors should be placed on the heat sinks through a thin layer of thermal paste, otherwise the efficiency of such cooling will be minimal.
5. Diodes used in induction heater, must be ultra-fast action. Most suitable for this circuit, diodes: MUR-460; UF-4007; HER - 307.
6. Resistors used in circuit 3: 10 kOhm with a power of 0.25 W - 2 pcs. and 440 ohms with a power of 2 watts. Zener Diodes: 2 pcs. with an operating voltage of 15 V. The power of the zener diodes must be at least 2 W. The choke for connection to the power terminals of the coil is used with induction.
7. To power the entire device, you will need a power supply unit with a capacity of up to 500 watts. and voltage 12 - 40 V. You can power this device from a car battery, but you will not be able to get the highest power readings at this voltage.

The process of manufacturing an electronic generator and a coil itself takes a little time and is carried out in the following sequence:

1. From copper pipe a spiral with a diameter of 4 cm is made. To make a spiral, a copper tube should be screwed onto a rod with a flat surface with a diameter of 4 cm. The spiral should have 7 turns, which should not touch. Mounting rings are soldered to the 2 ends of the tube for connecting to the radiators of the transistor.
2. The printed circuit board is manufactured according to the scheme. If it is possible to supply polypropylene capacitors, then due to the fact that such elements have minimal losses and stable operation at large amplitudes of voltage fluctuations, the device will work much more stable. The capacitors in the circuit are installed in parallel, forming an oscillatory circuit with the copper coil.
3. Metal heating occurs inside the coil after the circuit is connected to a power supply or battery. When heating the metal, it is necessary to ensure that there is no short circuit of the spring windings. If the heated metal touches 2 turns of the coil at the same time, then the transistors fail instantly.

Nuances

1. When conducting experiments on heating and quenching metals, inside the induction coil, the temperature can be significant and is 100 degrees Celsius. This heating effect can be used to heat domestic water or to heat a home.
2. Heater circuit discussed above (Figure 3), at maximum load is capable of providing radiation of magnetic energy inside the coil equal to 500 W. This power is not enough to heat a large volume of water, and the construction of a high-power induction coil will require the manufacture of a circuit in which it will be necessary to use very expensive radioelements.
3. A budget solution for the organization of induction heating of liquid, is the use of several devices described above, arranged in series. At the same time, the spirals should be on the same line and not have a common metal conductor.
4. Asused pipe made of of stainless steel with a diameter of 20 mm. Several induction coils are "strung" onto the pipe, so that the heat exchanger is in the middle of the coil and does not come into contact with its coils. With the simultaneous switching on of 4 such devices, the heating power will be about 2 kW, which is already enough for instantaneous heating of the liquid with a small circulation of water, up to values ​​that allow the use this design in supply warm water a small house.
5. If you connect such a heating element to a well-insulated tank, which will be located above the heater, then the result will be a boiler system in which the liquid will be heated inside stainless pipe, heated water will rise up, and a colder liquid will take its place.
6. If the area of ​​the house is significant, then the number of induction coils can be increased to 10 pieces.
7. The power of such a boiler can be easily adjusted. by turning off or turning on the spirals. The more sections that are simultaneously switched on, the more the power of the heating device operating in this way will be.
8. To power such a module, you will need a powerful power supply. If a DC inverter welding machine is available, then a voltage converter of the required power can be made from it.
9. Due to the fact that the system operates on a constant electric current, which does not exceed 40 V, the operation of such a device is relatively safe, the main thing is to provide a fuse block in the generator power circuit, which, in the event of a short circuit, will de-energize the system, thereby excluding the possibility of a fire.
10. Thus, you can organize "free" heating of the house., subject to installation for power supply induction devices rechargeable batteries, which will be charged by the energy of the sun and wind.
11. Batteries should be combined in sections of 2, connected in series. As a result, the supply voltage with such a connection will be at least 24 V., which will ensure the operation of the boiler at high power. Besides, serial connection will reduce the current in the circuit and increase the life of the batteries.

1. Exploitation homemade devices induction heating, does not always allow to exclude the spread of electromagnetic radiation harmful to humans, therefore the induction boiler should be installed in non-residential premises and shielded with galvanized steel.
2. Mandatory when working with electricity the safety regulations must be followed and, especially this applies to AC networks with a voltage of 220 V.
3. As an experiment can be made hob for cooking food according to the scheme specified in the article, but to operate this device permanently not recommended due to imperfection self-made shielding this device, because of this, the human body may be exposed to harmful electromagnetic radiation, which can adversely affect health.

Induction ovens were invented as early as 1887. And three years later, the first appeared industrial development, with the help of which various metals were melted. I would like to note that in those early years, these ovens were a wonder. The thing is that scientists of that time did not quite understand what processes were taking place in it. Today we figured it out. In this article, we will be interested in the topic - a do-it-yourself induction furnace. How simple is its design, is it possible to assemble this unit at home?

Principle of operation

It is necessary to start the assembly, having understood the principle of operation and the device of the device. Let's start with this. Pay attention to the picture above, and we will understand it.

The device includes:

• Generator G that generates alternating current.
• Capacitor C, together with coil L, creates an oscillatory circuit, which ensures the installation with a high temperature.
  

  Attention! Some designs use a so-called self-oscillating generator. This makes it possible to remove the capacitor from the circuit.

• The coil in the surrounding space forms a magnetic field in which there is a voltage, indicated in our figure by the letter "H". The magnetic field itself exists in free space, and can be closed through a ferromagnetic core.
• It also acts on the charge (W), in which it creates a magnetic flux (Ф). By the way, instead of a charge, some kind of blank can be installed.
• The magnetic flux induces a secondary voltage of 12 V. But this only happens if W is an electrically conductive element.
• If the workpiece to be heated is large and solid, then the so-called Foucault current begins to act inside it. It is of the vortex type.
• In this case, eddy currents are transmitted from the generator through the magnetic field thermal energy, thereby heating the workpiece.

The electromagnetic field is wide enough. And even the multistage energy conversion that is present in home-made induction furnaces has maximum efficiency- up to 100%.

Crucible furnace

Varieties

There are two main designs induction furnaces:

• Duct.
• Crucible.

We will not describe all of them here. distinctive features... Just note that the duct version is a design that looks like a welding machine. In addition, in order to melt the metal in such furnaces, it was necessary to leave a little melt, without which the process simply did not work. The second option is an improved scheme that uses the technology without residual melt. That is, the crucible is simply installed directly into the inductor.

How it works

Why do you need such a stove at home?

In general, the question is quite interesting. Let's consider this situation. There is enough a large number of Soviet electrical and electronic devices that used gold or silver contacts. You can remove these metals different ways... One of them is an induction oven.

That is, you take the contacts, put them in a narrow and long crucible, which you install in the inductor. After 15-20 minutes, reducing the power, cooling the apparatus and breaking the crucible, you will get a rod, at the end of which you will find a gold or silver tip. Cut and hand over to a pawnshop.

Although it should be noted that with this homemade unit can be carried out various processes with metals. For example, quenching or tempering can be done.

Coil with battery (generator)

Stove components

In the section "How it works" we have already mentioned all parts of the induction furnace. And if everything is clear with the generator, then the inductor (coil) should be dealt with. A copper tube is suitable for her. If you are assembling a device with a power of 3 kW, then you will need a tube with a diameter of 10 mm. The coil itself is twisted with a diameter of 80-150 mm, with the number of turns from 8 to 10.

Please note that the turns of the copper tube must not touch each other. Optimal distance between them 5-7 mm. The coil itself must not touch the screen. The distance between them is 50 mm.

Typically, industrial induction furnaces have a cooling unit. It is impossible to do this at home. But for a 3 kW unit, work up to half an hour does not threaten anything. True, over time, copper scale will form on the tube, which reduces the efficiency of the device. So the coil will have to be changed periodically.

Generator

In principle, making a generator with your own hands is not a problem. But this is possible only if you have sufficient knowledge in radio electronics at the level of an average radio amateur. If you don't have such knowledge, then forget about the induction stove. The most important thing is that it is also necessary to operate this device skillfully.

If you are faced with the dilemma of choosing a generator circuit, then take one piece of advice - it should not have a rigid current spectrum. In order to make it clearer what is at stake, we offer the simplest generator circuit for an induction furnace in the photo below.

Generator circuit

Required knowledge

The electromagnetic field affects all living things. An example is meat in the microwave. Therefore, it is worth taking care of safety. And it doesn't matter if you build the oven and test it or work on it. There is such an indicator as the energy flux density. So it depends on exactly electromagnetic field... And the higher the radiation frequency, the worse it is for the human body.

Many countries have adopted safety measures that take into account power density. There are developed tolerances. This is 1-30 mW per 1 m² of the human body. These indicators are valid if the irradiation occurs no more than one hour a day. By the way, the installed galvanized screen reduces the density of the ceiling by 50 times.

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Smelting of metal by the induction method is actively used in various industries, for example, mechanical engineering, metallurgy and jewelry production. The material is heated by an electric current, which makes it possible to use the heat with maximum efficiency... In large factories, there are special industrial units for this, while at home you can assemble a simple and small induction furnace with your own hands.

Such ovens are popular in production

Self-assembly of the oven

On the Internet and in magazines, there are many technologies and schematic descriptions of this process, but when choosing it is worth stopping at one model that is most effective in work, as well as affordable and easy to implement.

Homemade smelters are fairly simple in design and usually have only three main parts housed in a sturdy case. These include:

• element generating alternating current of high frequency;
• a spiral piece made from copper tubing or thick wire called an inductor
• crucible - a container in which calcination or melting will be carried out, made of refractory material.

Of course, such equipment is rarely used in everyday life, because not all craftsmen need such units. But the technologies found in these devices are present in household appliances which many people deal with almost every day. These include microwaves, electric ovens and induction cookers. You can make different equipment with your own hands according to the diagrams, if any necessary knowledge and skills.

In this video you will learn what this oven consists of.

Heating in this technique is carried out by induction eddy currents. The temperature rise occurs instantly, unlike other devices of a similar purpose.

For example, induction cookers have an efficiency of 90%, while gas and electric cookers cannot boast of this value, it is only 30-40% and 55-65%, respectively. However, HDTV plates have a drawback: for their operation, you will have to prepare special dishes.

Transistor construction

There are many different schemes for assembling induction smelters at home. A simple and proven furnace made of field-effect transistors is assembled quite easily, many craftsmen familiar with the basics of radio engineering will cope with its manufacture according to the scheme shown in the figure. To create a setup you need to prepare the following materials and details:

• two transistors IRFZ44V;
• copper wires (for winding) in enamel insulation, 1.2 and 2 mm thick (one piece each);
• two rings from chokes, they can be removed from the power supply unit of the old computer;
• one 470 Ohm 1 W resistor (you can connect two 0.5 W in series);
• two UF4007 diodes (easily replaced by the UF4001 model);
• film capacitors of 250 W - one piece with a capacity of 330 nF, four - 220 nF, three - 1 μF, 1 piece - 470 nF.

Before assembling such a furnace, do not forget about the tool.

The assembly takes place according to the schematic drawing, it is also recommended to check with step by step instructions, this will save you from errors and damage to elements. The creation of an induction melting furnace with your own hands is carried out according to the following algorithm:

1. The transistors are placed on rather large heat sinks. The fact is that circuits can get very hot during operation, so it is so important to choose the details suitable size... All transistors can be placed on one radiator, but in this case you will have to isolate them, eliminating contact with metal. Washers and gaskets made of plastic and rubber will help with this. The correct pinout of the transistors is shown in the picture.
2. Then they start making chokes, they will need two pieces. To do this, take a copper wire 1.2 mm in diameter and wrap it around the rings taken from the power supply. The composition of these elements includes ferromagnetic iron in the form of a powder, therefore, it is necessary to make at least 7-15 turns, leaving a small distance between them.
3. The resulting modules are assembled into one battery with a capacity of 4.6 μF, the capacitors are connected in parallel.
4. Copper wire 2 mm thick is used to wind the inductor. It is wrapped 7-8 times around any cylindrical object, its diameter should correspond to the size of the crucible. The excess wire is cut off, but rather long ends are left: they will be needed to connect to other parts.
5. All elements are connected on the board, as shown in the figure.

If necessary, you can build a case for the unit; for this purpose, only heat-resistant materials, such as textolite, are used. The power of the device can be adjusted, for which it is enough to change the number of turns of wire on the inductor and their diameter.

There are several variations of the induction oven that can be assembled

With graphite brushes

The main element of this structure is assembled from graphite brushes, the space between which is filled with granite, crushed to a powder state. Then ready module connected to a step-down transformer. When working with such equipment, you can not be afraid of electric shock, since it does not need to use 220 volts.

Manufacturing technology of an inductive furnace from graphite brushes:

1. First, the body is assembled, for this refractory (chamotte) brick measuring 10 × 10 × 18 cm is laid on a tile that can withstand high temperatures. The finished box is wrapped in asbestos cardboard. To give this material the required shape, it is enough to moisten it with a little water. The size of the base directly depends on the power of the transformer used in the structure. If desired, the box can be covered with steel wire.
2. An excellent option for graphite furnaces would be a 0.063 kW transformer taken from welding machine... If it is rated for 380V, it can be wound for safety reasons, although many experienced radio technicians believe that this procedure can be omitted without any risk. However, it is recommended to wrap thin aluminum around the transformer so that the finished device does not heat up during operation.
3. A clay substrate is placed at the bottom of the box so that the liquid metal does not spread, after which graphite brushes and granite sand are placed in the box.

The main advantage of such devices is considered heat melting, which is capable of changing the state of aggregation even of palladium and platinum. The disadvantages include too fast heating of the transformer, as well as a small furnace area, which will not allow smelting more than 10 g of metal at a time. Therefore, every craftsman should understand that if the device is going to handle large volumes, then it is better to make a furnace of a different design.

Appliance on lamps

A powerful melting stove can be assembled from electronic bulbs. As can be seen in the diagram, in order to obtain high-frequency current, it is necessary to connect the beam lamps in parallel. Instead of an inductor, this device uses a copper tube with a diameter of 10 mm. Also, the design is equipped with a trimmer capacitor in order to be able to regulate the power of the furnace. For assembly, you need to prepare:

• four lamps (tetrodes) L6, 6P3 or G807;
• trimmer capacitor;
• 4 chokes for 100-1000 μH;
• neon indicator light;
• four capacitors of 0.01 μF.

To begin with, the copper tube is shaped into a spiral - this will be the inductor of the device. In this case, a distance of at least 5 mm is left between the turns, and their diameter should be 8-15 cm. The ends of the spiral are processed to attach to the circuit. The thickness of the resulting inductor should be 10 mm larger than that of the crucible (it is placed inside).

The finished part is placed in the housing. For its manufacture, you should use a material that will provide electrical and thermal insulation of the filling of the device. Then a cascade is assembled from lamps, chokes and capacitors, as shown in the figure, the latter are connected in a straight line.

It's time to connect the neon indicator: it is needed so that the master can find out about the readiness of the device for work. This light bulb is brought out to the furnace body together with the handle of the variable capacitor.

Cooling system equipment

Industrial units for metal melting are equipped with special cooling systems for antifreeze or water. Additional costs will be required to equip these important installations in home-made HDTV stoves, which can significantly hit the wallet with the assembly. Therefore, it is better to provide the household unit with a cheaper system consisting of fans.

Air cooling by these devices is possible when they are located remotely from the furnace. V otherwise the metal winding and parts of the fan can act as a circuit for closing eddy currents, which will significantly reduce the efficiency of the equipment.

Lamp and electronic circuits also tend to heat up actively during unit operation. Heat sinks are usually used to cool them.

Terms of use

For experienced radio technicians, assembling an induction furnace according to diagrams with their own hands may seem like an easy task, so the device will be ready pretty quickly, and the master will want to try his creation in action. It is worth remembering that when working with homemade installation it is important to observe safety precautions and not forget about the main threats that may arise during the operation of an inertial oven:

1. Liquid metal and heating elements accessories can cause severe burns.
2. Lamp circuits consist of parts with high voltage, therefore, during assembly of the unit, they must be placed in a closed box, thus eliminating the possibility of accidental touching these elements.
3. The electromagnetic field is capable of influencing even those things that are outside the installation box. Therefore, before turning on the device, you need to remove all complex technical devices, such as mobile phones, digital cameras, MP3 players, and remove all metal decorations. People with pacemakers are also at risk: they should never use such equipment.

These furnaces can be used not only for melting, but also for rapid heating metal objects during molding and tinning. By changing the output signal of the installation and the parameters of the inductor, you can configure the device for a specific task.

For melting small amounts of iron, they will go homemade stoves, these efficient devices are capable of operating from conventional wall outlets. The device does not take up much space, it can be placed on the desktop in the workshop or garage. If a person knows how to read simple electrical diagrams, then he does not need to purchase such equipment in a store, because he can assemble a small stove with his own hands in just a few hours.

Radio amateurs have long figured out that you can make do-it-yourself induction furnaces for melting metal. These simple schemes help to make a TV set for home use... However, it would be more correct to call all the described designs Kukhtetsky laboratory inverters, since it is simply impossible to assemble a full-fledged stove of this type on your own.

The very principle of operation of an induction furnace is that the heat for melting is obtained from electricity, which is generated by alternating magnetic field... In such furnaces, energy is converted from electromagnetic, then into electrical, and ultimately into heat. How is an induction oven made with your own hands?

Such ovens are divided into two types:

1. Crucible. In such furnaces, the inductor and core are inside the metal. This type of furnace is used in industrial smelters, for smelting copper, aluminum, cast iron, steel, as well as in jewelry factories for smelting precious metals.
2. Duct. In this kind of ovens, the inductor and the core are around the metal.

Compared to boilers or other stoves, induction stoves have a number of advantages:

• instantly warm up;
• focusing energy in a given range;
• environmentally friendly device and relative safety;
• there is no waste;
• huge possibilities for adjusting temperature and capacity;
• the uniformity of the metal that melts.

Induction ovens are also used for heating. It is a convenient and at the same time quiet heating method.

Does not require a special boiler room. Scale does not accumulate on the heating element, but for circulation through heating system you can use any liquid, be it oil, water, or others. Also, the oven is durable, as it is minimally worn out. As mentioned earlier, it is very environmentally friendly, because there are no harmful emissions into the air, and also meets all fire safety requirements.

Collection of information

It will not be difficult for a person who understands how to read and understand an electrical circuit to figure out how to make such an induction furnace. On the Internet, you will see dozens or even hundreds of options for making various induction furnaces using household junk, for example, from an old microwave oven or a welding inverter.

Be sure to remember that electricity Is a dangerous thing. And to make an induction furnace, you need to have an idea of ​​what induction heating is. It is advisable that you have a person with you who understands at least the basics of electrical engineering or has experience with electrical equipment.

Principle of operation

The basis of the operation of such a stove is to extract heat from an electric current, which generates an alternating magnetic field using an inductor. It turns out that we get heat first from electromagnetic energy, and then from electrical energy. The closure of the currents that flow through the turns of the inductor (inductor) releases heat and heats up the metal from the inside.

Such a furnace can operate in a simplified version and operate on a 220V home network. But this requires a rectifier, that is, an adapter.

Furnace device

The construction of an induction device is similar to that of a transformer. In it, the primary winding is supplied with alternating current, and the secondary one serves as a heated body.

The simplest inductor is considered to be an insulated conductor (in the form of a spiral or core), which is located on the surface metal pipe or inside it.

Here are some of the nodes that work by induction:

• inductor;
• melting furnace compartment;
• heating element for a heating furnace;
• generator;
• frame.

Induction furnaces are used for smelting metals and differ in that they are heated by means of an electric current. Excitation of the current occurs in the inductor, or rather in the non-alternating field.

In such constructions, energy is converted several times (in this sequence):

• into electromagnetic;
• electric;
• thermal.

Such ovens allow using heat with maximum efficiency, which is not surprising, because they are the most advanced of all existing models that run on electricity.

Note! Induction structures are of two types - with or without a core. In the first case, the metal is placed in a tubular groove, which is located around the inductor. The core is located in the inductor itself. The second option is called crucible, because in it the metal with the crucible is already inside the indicator. Of course, there can be no question of any core in this case.

Today's article will focus on how to makeDIY induction furnace.

Among the many advantages, the following are worth highlighting:

• ecological cleanliness and safety;
• increased homogeneity of the melt due to the active movement of the metal;
• fast response - the oven can be used almost immediately after switching on;
• zone and focused direction of energy;
• high melting rate;
• no waste from alloying substances;
• the ability to adjust the temperature;
• numerous technical possibilities.

But there are also disadvantages.

1. The slag is heated by the metal, as a result of which it has a low temperature.
2. If the slag is cold, then it is very difficult to remove phosphorus and sulfur from the metal.
3. The magnetic field is dissipated between the coil and the molten metal, therefore a reduction in the thickness of the lining will be required. This will soon lead to the fact that the lining itself will fail.

Video - Induction oven

Industrial application

Both designs are used in the smelting of iron, aluminum, steel, magnesium, copper and precious metals. The useful volume of such structures can be as much as several kilograms and several hundred tons.

Ovens industrial use are divided into several types.

1. Medium frequency designs are commonly used in mechanical engineering and metallurgy. With their help, steel is melted, and when using graphite crucibles and non-ferrous metals.
2. Constructions industrial frequency used in pig iron smelting.
3. Resistance structures are intended for melting aluminum, aluminum alloys, zinc.

Note! It was the induction technology that formed the basis of the more popular devices - microwave ovens.

Domestic use

For obvious reasons, induction smelting furnaces are not commonly used in the home. But the technology described in the article is found in almost all modern houses and apartments. These are the microwave ovens mentioned above, induction cookers, and electric ovens.

Consider slabs, for example. They heat the cookware by means of induction eddy currents, as a result of which heating occurs almost instantly. It is characteristic that it is impossible to turn on a hotplate without dishes on it.

The efficiency of induction cookers reaches 90%. For comparison: for electric stoves, it is about 55-65%, and for gas - no more than 30-50%. But in fairness, it is worth noting that for the operation of the described stoves, special dishes are required.

Homemade induction furnace

Not so long ago, domestic radio amateurs clearly demonstrated that an induction furnace can be made by yourself. Today there are a lot of different schemes and manufacturing technologies, but we have given only the most popular of them, which means that the most effective and easy to implement.

High frequency generator induction furnace

Below is the electrical circuit for the manufacture of homemade appliance from a high-frequency (27.22 megahertz) generator.

In addition to the generator, assembly will require four high power light bulbs and a heavy duty light bulb for the ready-to-operate indicator.

Note! The main difference between a furnace made according to this scheme is the condenser handle - in this case, it is located outside.

In addition, the metal in the coil (inductor) will melt in the device of the smallest power.

When making, it is necessary to remember some important points influencing the rate of metal reign. It:

• power;
• frequency;
• eddy losses;
• heat transfer intensity;
• hysteresis loss.

The device will be powered from a standard 220 V mains, but with a pre-installed rectifier. If the furnace is intended for heating a room, it is recommended to use a nichrome spiral, and if for melting, then graphite brushes. Let's get acquainted with each of the designs in more detail.

Video - Construction from a welding inverter

The essence of the design is as follows: a pair of graphite brushes is installed, and powder granite is poured between them, after which the connection to the step-down transformer is carried out. It is characteristic that when smelting, you can not be afraid of an electric shock, since there is no need to use 220 V.

Assembly technology

Step 1. Assembling the base - box of fireclay bricks 10x10x18 cm in size, laid on refractory tiles.

Step 2. The box is finished with asbestos board. After wetting with water, the material softens, which allows you to give it any shape. If desired, the structure can be wrapped with steel wire.

Note! The dimensions of the box may vary depending on the power of the transformer.

Step 3. The best option for a graphite furnace - a transformer from a welding machine with a power of 0.63 kW. If the transformer is rated for 380V, then it can be rewound, although many experienced electricians claim that you can leave it as it is

Step 4. The transformer is wrapped with thin aluminum - so the structure will not get very hot during operation.

Step 5. Graphite brushes are installed, a clay substrate is installed on the bottom of the box - so the molten metal will not spread.

The main advantage of such a furnace is the high temperature, which is even suitable for melting platinum or palladium. But among the minuses is the rapid heating of the transformer, a small volume (no more than 10 g can be melted at a time). For this reason, a different design will be required for melting large volumes.

So, for smelting large volumes of metal, a furnace with nichrome wire... The principle of operation of the structure is quite simple: an electric current is supplied to a nichrome spiral, which heats up and melts the metal. There are many different formulas for calculating the length of a wire on the Web, but they are all, in principle, the same.

Step 1. For the spiral, ø0.3 mm nichrome is used with a length of about 11 m.

Step 2. The wire must be wound. This requires a straight line copper tubeø5 mm - the spiral is wound on it.

Step 3. A small ceramic tube ø1.6 cm and 15 cm long is used as a crucible. One end of the tube is plugged with an asbestos thread - so the molten metal will not flow out.

Step 4. After checking the functionality and the spiral is laid around the pipe. In this case, the same asbestos thread is placed between the turns - it will prevent short circuits and limit the access of oxygen.

Step 5. The finished coil is placed in a high power lamp socket. These cartridges are usually ceramic and are sized appropriately.

The advantages of this design:

• high productivity (up to 30 g at one run);
• fast heating (about five minutes) and long cooling;
• ease of use - it is convenient to pour metal into molds;
• prompt replacement of the coil in case of burnout.

But, of course, there are also disadvantages:

• nichrome burns out, especially if the spiral is poorly insulated;
• insecurity - the device is connected to a 220 V power supply.

Note! You cannot add metal to the stove if the previous portion has already been melted there. Otherwise, all the material will fly around the room, moreover, it can injure the eyes.

As a conclusion

As you can see, an induction furnace can still be made on your own. But to be frank, the described design (like everything on the Internet) is not really an oven, but a Kukhtetsky laboratory inverter. Collect the same full induction design at home is simply impossible.