DIY induction muffle furnace. Melting metal at home in an induction electric furnace

The most perfect type of heating is one in which heat is created directly in the heated body. This method of heating is very well carried out by passing an electric current through the body. However, direct - the inclusion of a heated body in an electrical circuit is not always possible for technical and practical reasons.

In these cases, the perfect type of heating can be achieved by using induction heating, in which heat is also created in the heated body itself, which eliminates unnecessary, usually large, energy consumption in the walls of the furnace or in other heating elements. Therefore, despite the relatively low efficiency of generating high and high frequency currents, the overall efficiency of induction heating is often higher than.

The induction method also allows rapid heating of non-metallic bodies evenly throughout their entire thickness. The poor thermal conductivity of such bodies excludes the possibility of rapid heating of their inner layers in the usual way, i.e., by supplying heat from outside. With the induction method, heat is generated in the same way both in the outer layers and in the inner ones, and there may even be a danger of overheating of the latter if the necessary thermal insulation of the outer layers is not made.

A particularly valuable property of induction heating is the possibility of a very high concentration of energy in the heated body, which is easily amenable to precise dosage. It is only possible to obtain the same order of energy density, however, this method of heating is difficult to control.

Features and well-known advantages of induction heating have created a wide range of applications in many industries. In addition, it allows you to create new types of structures that are not at all feasible using conventional heat treatment methods.

physical process

In induction furnaces and devices, heat in an electrically conductive heated body is released by currents induced in it by an alternating electromagnetic field. Thus, direct heating is carried out here.

Induction heating of metals is based on two physical laws: and the Joule-Lenz law. Metal bodies (blanks, parts, etc.) are placed in, which excites a vortex in them. The induction emf is determined by the rate of change of the magnetic flux. Under the action of the induction EMF, eddy currents (closed inside the bodies) flow in the bodies, releasing heat. This EMF creates in the metal, the thermal energy released by these currents is the cause of the heating of the metal. Induction heating is direct and non-contact. It allows you to reach a temperature sufficient to melt the most refractory metals and alloys.

Intensive induction heating is possible only in electromagnetic fields of high intensity and frequency, which are created by special devices - inductors. The inductors are powered from a 50 Hz network (power frequency installations) or from individual power sources - generators and medium and high frequency converters.

The simplest inductor of low-frequency indirect induction heating devices is an insulated conductor (stretched or coiled) placed inside a metal pipe or superimposed on its surface. When current flows through the conductor-inductor, heating pipes are induced in the pipe. The heat from the pipe (it can also be a crucible, container) is transferred to the heated medium (water flowing through the pipe, air, etc.).

Induction heating and hardening of metals

The most widely used direct induction heating of metals at medium and high frequencies. For this, special inductors are used. The inductor emits , which falls on the heated body and decays in it. The energy of the absorbed wave is converted in the body into heat. The heating efficiency is the higher, the closer the type of the emitted electromagnetic wave (flat, cylindrical, etc.) to the shape of the body. Therefore, flat inductors are used to heat flat bodies, cylindrical billets - cylindrical (solenoid) inductors. In the general case, they can have a complex shape, due to the need to concentrate electromagnetic energy in the right direction.

A feature of the induction energy input is the possibility of controlling the spatial arrangement of the flow zone.

First, eddy currents flow within the area covered by the inductor. Only that part of the body that is in magnetic connection with the inductor is heated, regardless of the overall dimensions of the body.

Secondly, the depth of the eddy current circulation zone and, consequently, the energy release zone depends, among other factors, on the frequency of the inductor current (increases at low frequencies and decreases with increasing frequency).

The efficiency of energy transfer from the inductor to the heated current depends on the size of the gap between them and increases with its decrease.

Induction heating is used for surface hardening of steel products, through heating for plastic deformation (forging, stamping, pressing, etc.), melting of metals, heat treatment (annealing, tempering, normalization, hardening), welding, surfacing, soldering of metals.

Indirect induction heating is used for heating process equipment (pipelines, tanks, etc.), heating liquid media, drying coatings, materials (for example, wood). The most important parameter of induction heating installations is frequency. For each process (surface hardening, through heating) there is an optimal frequency range that provides the best technological and economic performance. For induction heating, frequencies from 50 Hz to 5 MHz are used.

Advantages of induction heating

1) The transfer of electrical energy directly into the heated body allows direct heating of conductor materials. This increases the heating rate compared to indirect installations, in which the product is heated only from the surface.

2) The transfer of electrical energy directly into the heated body does not require contact devices. This is convenient in conditions of automated in-line production, when using vacuum and protective equipment.

3) Due to the phenomenon of the surface effect, the maximum power is released in the surface layer of the heated product. Therefore, induction heating during hardening provides rapid heating of the surface layer of the product. This makes it possible to obtain a high surface hardness of the part with a relatively viscous middle. The process of surface induction hardening is faster and more economical than other methods of surface hardening of the product.

4) Induction heating in most cases can increase productivity and improve working conditions.

Induction Melting Furnaces

An induction furnace or device can be viewed as a kind of transformer in which the primary winding (inductor) is connected to an alternating current source, and the heated body itself serves as the secondary winding.

The working process of induction melting furnaces is characterized by electrodynamic and thermal movement of liquid metal in a bath or crucible, which contributes to the production of a metal homogeneous in composition and its uniform temperature throughout the volume, as well as low metal waste (several times less than in arc furnaces).

Induction melting furnaces are used in the production of castings, including shaped ones, from steel, cast iron, non-ferrous metals and alloys.

Induction melting furnaces can be divided into industrial frequency channel furnaces and industrial, medium and high frequency crucible furnaces.

The induction channel furnace is a transformer, usually industrial frequency (50 Hz). The secondary winding of the transformer is a coil of molten metal. The metal is enclosed in an annular refractory channel.

The main magnetic flux induces an EMF in the channel metal, the EMF creates a current, the current heats the metal, therefore, an induction channel furnace is similar to a transformer operating in a short circuit mode.

Inductors of channel furnaces are made of a longitudinal copper tube, it is water-cooled, the channel part of the hearthstone is cooled by a fan or from a centralized air system.

Induction channel furnaces are designed for continuous operation with rare transitions from one metal grade to another. Induction channel furnaces are mainly used for melting aluminum and its alloys, as well as copper and some of its alloys. Other series of furnaces are specialized as mixers for holding and superheating liquid iron, non-ferrous metals and alloys before pouring into molds.

The operation of an induction crucible furnace is based on the absorption of electromagnetic energy from a conductive charge. The cage is placed inside a cylindrical coil - an inductor. From an electrical point of view, an induction crucible furnace is a short-circuited air transformer, the secondary winding of which is a conductive charge.

Induction crucible furnaces are mainly used for melting metals for shaped castings during batch operation, and also, regardless of the operating mode, for melting certain alloys, such as bronzes, which adversely affect the lining of channel furnaces.

For melting metal on a small scale, some kind of device is sometimes necessary. This is especially acute in the workshop or in small production. The most effective at the moment is a furnace for melting metal with an electric heater, namely induction. Due to the peculiarity of its structure, it can be effectively used in blacksmithing and become an indispensable tool in the forge.

Induction furnace device

The oven consists of 3 elements:

1. 1. Electronic-electrical part.
2. 2. Inductor and crucible.
3. 3. inductor cooling system.

In order to assemble an operating furnace for melting metal, it is enough to assemble a working electrical circuit and an inductor cooling system. The easiest option for melting metal is shown in the video below. Melting is performed in the counter electromagnetic field of the inductor, which interacts with the induced electro-eddy currents in the metal, which keeps a piece of aluminum in the space of the inductor.

In order to effectively melt the metal, currents of large magnitude and high frequency of the order of 400-600 Hz are required. The voltage from an ordinary 220V household outlet has sufficient data to melt metals. It is only necessary to turn 50 Hz into 400-600 Hz.
Any scheme for creating a Tesla coil is suitable for this.

Tins and other scrap - for recycling! How to make a do-it-yourself aluminum melting furnace

I liked the following 2 schemes on the lamp GU 80, GU 81 (M). And powering the lamp with an ILO transformer from a microwave.

These circuits are designed for a Tesla coil, but an induction furnace is excellent from them; instead of the secondary coil L2, it is enough to place a piece of iron in the interior of the primary winding L1.

The primary coil L1 or inductor consists of a copper tube rolled into 5-6 turns, at the ends of which a thread is cut to connect the cooling system. For levitational melting, the last turn should be done in the opposite direction.
Capacitor C2 on the first circuit and identical to it on the second sets the frequency of the generator. At a value of 1000 pF, the frequency is about 400 kHz. This capacitor must be high-frequency ceramic and designed for high voltage of the order of 10 kV (KVI-2, KVI-3, K15U-1), other types are not suitable! Better to put K15U. You can connect capacitors in parallel. It is also worth considering the power for which the capacitors are designed (this is written on the case), take it with a margin. the other two capacitors KVI-3 and KVI-2 heat up during prolonged operation. All other capacitors are also taken from the KVI-2, KVI-3, K15U-1 series, only the capacitance changes in the characteristics of the capacitors.
Here's a schematic of what it should look like. Framed 3 blocks.

The cooling system is made of a pump with a flow of 60 l / min, a radiator from any VAZ car, and I put a regular home cooling fan in front of the radiator.

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Masters of their craft: we make a melting furnace

A smelting furnace is a large or portable facility in which some non-ferrous metal can be melted. The induction melting furnace is widely known. In industrial conditions, for melting metal in large quantities, induction melting furnaces of considerable size are installed in special rooms. They melt metal, from which many parts for motorcycles, cars, tractors are cast. To melt up to 5 kg of aluminum. you can build your own induction melting furnaces, solid fuel, gas installations. They all work great. How and from what can you make a home melter?

We build our own furnace for melting

The installation for melting metal (Fig. 1) is assembled from bricks. It must be fireproof. Chamotte clay is used as a binder. To burn the device with coal, forced air is needed. For it, in the lower half of the unit, it is necessary to leave a special channel for air access. A grate is placed under this channel. This is a special cast-iron grate on which coal or coke is laid out. The grate can be used from an old stove or purchased on the market, in a hardware store. For strength, some scald the finished structure with a metal belt. Brick can be placed on edge.

A melting furnace cannot do without a crucible. Instead, you can use a cast-iron cauldron. It can be found on the farm. Well, if it turns out to be enameled. The crucible is placed closer to the burning coke. It remains to put a fan as a forced blower, light the coke and start melting. Do-it-yourself oven is ready. It can be used for melting cast iron, copper, bronze, aluminum.

Construction of a tabletop oven

From simple materials, you can build gas or electric devices that fit perfectly on a table or workbench. For work you will need:

Asbestos has been banned for domestic use in recent years, so it can be replaced with tile or cement tiles. Dimensions depend on the desire of the owner. An important role here is played by the power of the electrical network and the output voltage of the transformer. It is enough to apply a voltage of 25 V to the electrodes. For an industrial transformer used in welding, this voltage is usually 50-60 V. In this case, the distance between the electrodes must be increased. Much is done by experience. As a result, melting 60-80 g of metal is a good result.

Electrodes are best made from brushes from a fairly powerful electric motor. They have a very handy power cord. You can carve them yourself. There should be no big problems with finding material. In a home-made product, you need to drill holes with a diameter of 5-6 mm on the side, insert a copper stranded wire with a thickness of about 5 mm into them, carefully hammer in a nail to secure the wire. It remains to make a notch with a file, it will help to improve contact with graphite in powder form. Inside the furnace is laid out with mica. This is an excellent thermal insulator. Outside, the walls of the furnace are reinforced with tiles.

To power the furnace, you can take a transformer that lowers the mains voltage to 52 V. The mains winding is wound with 620 turns of wire Ø1 mm. The lowering winding is wound with a 4.2x2.8 mm wire with fiberglass insulation. Number of turns #8212; 70. The furnace is connected to the transformer with wires with a cross section of 7-8 mm² in good insulation. The finished installation must be turned on for a while so that all organic inclusions burn out. The stove is assembled by hand.

• using a scoop or spatula, pour graphite and make a hole in it;
• a material blank is laid in the hole;
• precious metals must be placed in a glass ampoule;
• tin and aluminum are placed in a separate iron cup;
• for alloys, refractory metal is melted first, then low-melting metal.

It is impossible to melt magnesium, zinc, cadmium, silver contacts in such furnaces.

When melted, cadmium burns out with the formation of poisonous yellow smoke.

When working with the installation, you must observe safety precautions:

1. Do not allow short circuits in the wires.
2. The mains switch must be located near the operator.
3. Do not leave the device unattended during operation.
4. Nearby there is always a container in which water is poured, in which the workpieces are cooled.
5. For melting cast iron and other metals, goggles and gloves must be used.

If desired, gas installations can be made. They are well suited for melting small batches of non-ferrous metal. Induction furnaces for melting are capable of melting any metals. They can be used as conventional installations for working with non-ferrous and precious metals, as melting holding furnaces in production. They are suitable for various needs: for heating metals, for the manufacture of alloys of several metals, for the smelting of cast iron.

You can melt a small piece of iron in a self-assembled induction furnace. This is the most efficient device that runs on a 220V home outlet. The oven is useful in the garage or workshop, where it can be placed simply on the desktop. It makes no sense to buy it, since a do-it-yourself induction furnace is assembled in a couple of hours if a person can read electrical circuits. It is undesirable to do without a diagram, because it gives a complete picture of the device and allows you to avoid connection errors.

Scheme of the induction furnace

Parameters of the induction furnace

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How to properly assemble an induction furnace?

Helping a repairman

We offer your review for self-repair of electrical circuits of electric stoves!

Plates of Russian and imported production are presented, which do not change for years.
Click on the picture to enlarge the view.

The main elements and units of the stove: heating element E1 (in the first burner), E2 (in the second burner), E3-E5 (in the oven), a switching unit consisting of switches S1-S4, thermal relay F type T-300, indicators HL1 and HL (gas-discharge to indicate the operation of the heating element), HL3 (incandescent type to illuminate the oven). The power of each heating element is about 1 kW

A 4-position switch S1 is used to adjust the power and degree of heating of the heating element of the oven. When its handle is set to the first position, contacts P1-2 and P2-3 will close. At the same time, the following will be connected to the network using a plug: TEN E3 in series with parallel connected TEN E2 and E3. The current will pass along the path: the lower contact of the XP, F, P1-2, E4 and E5, E3, P2-3, upper HR plug contact. Since the E3 heater is connected to the E4 and E5 heaters in series, the 38 circuit resistance will be maximum, and the power and degree of heating will be minimal. In addition, the neon indicator HL1 will glow due to the passage of current through the circuit: the lower contact of the XP plug, F, P1-2, E4 and E5, R1, HL1, the upper contact XP.

Connecting nodes Dream 8:

In the second position, contacts P1-1, P2-3 are switched on. In this case, the current will flow through the circuit: the lower contact of the plug XP, F, P1-1, E3, P2-3, the upper contact XP. In this situation, only one heating element E3 will work and the power will be greater due to a decrease in the total resistance at a constant mains voltage of 220V.

In the third position of the switch S1, the contacts P1-1, P2-2 will close, which will lead to the connection to the network of only parallel connected heating elements E4 and E5. Switch S4 is used to turn on the oven light HL3.

5.Elektra 1002

H1, H2 - tubular burners, H3 - cast iron burner 200mm, H4 - cast iron burner 145mm, P1, P2-stepless power controls, P3, P4-seven-position power switches, PSH - three-stage oven switch, P5-blocking switch, L1 .... L4 - signal lamps for turning on the burners, L5 - signal lamp for turning on the heaters of the oven or grill, L6 - signal lamp for reaching the set temperature in the oven, H5, H6 - heaters for the oven, H7 - grill, T - thermostat, B - key switch, L7 - oven lighting lamp, M - motor reducer.

6. BURNER SWITCHES Combustion, Hansa, Elektra, Lysva:

Table of contents:

1. Principle of operation
2. Parameters of the induction furnace
3. Features of the operation of the inductor

You can melt a small piece of iron in a self-assembled induction furnace.

How to make a crucible or melting furnace with your own hands

This is the most efficient device that runs on a 220V home outlet. The oven is useful in the garage or workshop, where it can be placed simply on the desktop. It makes no sense to buy it, since a do-it-yourself induction furnace is assembled in a couple of hours if a person can read electrical circuits. It is undesirable to do without a diagram, because it gives a complete picture of the device and allows you to avoid connection errors.

The principle of operation of the induction furnace

A home-made induction furnace for melting a small amount of metal does not require large dimensions and such a complex device as industrial units. Its work is based on the generation of current by an alternating magnetic field. The metal is melted in a special blank called a crucible and placed in an inductor. It is a spiral with a small number of turns of a conductor, such as a copper tube. If the device is used for a short time, the conductor will not overheat. In such cases, it is sufficient to use copper wire.

A special generator launches powerful currents into this spiral (inductor), and an electromagnetic field is created around it. This field in the crucible and in the metal placed in it creates eddy currents. It is they who heat the crucible and melt the metal due to the fact that it absorbs them. It should be noted that the processes occur very quickly if a non-metal crucible is used, for example, fireclay, graphite, quartzite. A home-made melting furnace provides for a removable crucible design, that is, metal is placed in it, and after heating or melting, it is pulled out of the inductor.

Scheme of the induction furnace

The high frequency generator is assembled from 4 electron tubes (tetrodes), which are connected in parallel. The heating rate of the inductor is controlled by a variable capacitor. Its handle is brought out and allows you to adjust the capacitance of the capacitor. The maximum value will provide heating of a piece of metal in the coil in just a few seconds to a red state.

Parameters of the induction furnace

The effective operation of this device depends on the following parameters:

• generator power and frequency,
• the amount of eddy current losses,
• the rate of heat loss and the amount of these losses to the surrounding air.

How to choose the components of the circuit in order to obtain sufficient conditions for melting in the workshop? The generator frequency is pre-set: it should be 27.12 MHz if the device is assembled by hand for use in a home workshop. The coil is made of a thin copper tube or wire, PEV 0.8. It is enough to make no more than 10 turns.

Electronic lamps should be used with high power, for example, brand 6p3s. The scheme also provides for the installation of an additional neon lamp. It will serve as an indicator of device readiness. The circuit also provides for the use of ceramic capacitors (from 1500V) and chokes. Connection to a home outlet is carried out through a rectifier.

Externally, a home-made induction furnace looks like this: a generator with all the details of the circuit is attached to a small stand with legs. An inductor (spiral) is connected to it. It should be noted that this assembly option for a home-made melting device is applicable for working with a small amount of metal. The inductor in the form of a spiral is the easiest to make, therefore, for a home-made device, it is used in this form.

Features of the operation of the inductor

However, there are many different modifications of the inductor. For example, it can be made in the shape of a figure eight, trefoil, or any other shape. It should be convenient for placing material for heat treatment. For example, a flat surface is easiest to heat with serpentine coils.

In addition, it tends to burn through, and in order to extend the life of the inductor, it can be insulated with heat-resistant material. Use, for example, filling with a refractory mixture. It should be noted that this device is not limited to copper wire material. You can also use steel wire or michrome. When working with an induction furnace, its thermal hazard must be taken into account. If accidentally touched, the skin gets a severe burn.

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Homemade melting crucible electric furnace.

EN

So, a furnace for melting metal. Here I did not invent anything much, but simply tried to make a device, if possible from ready-made components and, if possible, without giving any slack in the manufacturing process.
At the furnace, the upper part is called the melter, the lower part is the control unit.
Don't let the white box on the right scare you - this is, in general, an ordinary transformer.
The main parameters of the furnace:
– furnace power - 1000 W
– crucible volume - 62 cm3
– maximum temperature - 1200 grC

smelter

Since my task was not to waste time on experiments with corundum-phosphate binders, but to save time by using ready-made components, I used a ready-made heater from YASAM, as well as a ceramic muffle working with it.

Heater: Fechral, ​​wire diameter 1.5 mm, rods 3 mm in diameter are welded to the terminals. Resistance 5 ohm. The presence of a muffle is mandatory, since the wires inside the heater are bare. Heater size Ф60/50х124 mm. Muffle dimensions Ф54.5/34х130 mm. In the bottom of the muffle we make a hole for the elevator rod.
The body of the melter is made of standard stainless steel. 220/200 pipe machined to an acceptable wall thickness. The height is also taken for a reason. Since we will have a fireclay brick as a lining, the height is taken taking into account three brick thicknesses. It's time to post the assembly drawing. In order not to clutter up the page, I will not publish here, but I will give links: Part1, Part2.
The first drawing does not show the lightweight fireclay washer on which the crucible rests, the height of the washer depends on the crucible used. There is a hole for the rod in the center of the washer. The rod is pointed and in the lower position does not reach the crucible.
As I already wrote, the lining of the furnace is made of fireclay lightweight bricks ШЛ 0.4 or ШЛ 0.6 of size No. 5. Its dimensions are 230x115x65 mm. Brick is easily processed with saws and sandpaper. Saws, however, will not last long 🙂 Fireclay brick processing. On the right is the original brick 🙂
Rectilinear cuts - a hacksaw for wood, for curved cuts - a home-made saw from a hacksaw blade with large teeth, with a reduced (grinded) blade width.

In the manufacture of lining, simple rules should be observed:
- do not use any mortar to hold the parts together. Everything is dry. It still breaks
— parts of the lining should not abut anywhere. There must be slack, gaps
- large parts of the lining, if you make it from another material, it is better to divide it into small parts. It will still split. Therefore, you better do it.

For the thermocouple in the third layer we make a hole, and in the second and first layers we make a gap between the heater and the lining. The gap is such that the thermocouple is pushed in tightly, as close as possible to the heater. You can use a purchased thermocouple in the same place in YASAM, but I use homemade ones. It's not that I feel sorry for the money (although they are quite expensive there), I just basically leave a bare junction for better thermal contact. Although there is a risk of burning the input circuits of the regulator.

Control block

In the control unit, the lower and upper covers are equipped with grilles for cooling the heater leads. All the same, the diameter of the pins is 3 mm. In addition, heat radiation through the bottom of the melter is also present. The regulator does not need to be cooled - 10 watts in total. At the same time, cool the cold ends of the thermocouple. Control unit with temperature controller Termodat-10K2. Top right is the on/off switch. At the top left is the crucible lift lever with the lift rod (stainless steel electrode Ф3mm).

Why I chose Termodat as a regulator. I dealt with Aries, but after one winter in an unheated room, his firmware crashed. The thermodat has withstood several winters and has retained not only the firmware, but also the settings.

Crucible furnace: design options, do-it-yourself manufacturing

In addition, the case is metal, indestructible. (We should at least take a bubble from Permians, for advertising 🙂
In addition, they can also take a power element - the Triac Control Unit BUS1-V01. This block is designed to work with Thermodata.
The instruction for Termodat-10K2 is here.

Diagram of an electric oven. The thick line shows high-current circuits. They use a wire of at least 6 mm2.

I'll talk about the transformer later. Now about the control unit. It is turned on by the T1 toggle switch, protected by a 0.25 A fuse. In addition, a line filter is provided to power the regulator, which is located in the transformer housing. A triac TS142-80 (1420 volts, 80 amperes, ordered in CHIP and DIP) is used as a power element. I put the triac on a radiator, but as practice has shown, it almost does not heat up. Do not forget to isolate the triac from the case. Or mica, or ceramics. Either the triac itself, or assembled with a radiator.

In the photo, behind the Thermodat, there is a fan power supply. I then added it to the fan, which I placed on the lower grille. The power supply unit is the simplest - trans, bridge and capacitor, produces 12 volts. Computer fan.
Heater outlet. Through the grate output in a ceramic tube. To connect to the terminal, I used a bolt drilled across.
Entering a thermocouple into the control unit. If you do not have such a ceramic tube, send the required amount to YaSAM.

Please note - the installation is made with an ordinary mounting wire, high-current circuits - stranded at least 6 mm2, thermocouple ends - directly into the terminal block. BUS in the factory form does not fit, I had to remove the cover - (and who is easy now? ;). The rest can be seen in the photo.

Transformer.

Despite such a formidable appearance, this device is a conventional 1 kW transformer. It's just that before that he changed several professions (graphite smelter, welder, etc.) and got a case, an automatic switch, an indicator of the current consumed from the network, and other wonderful things.

Of course, you do not have to fence all this, a simple kilowatt trance under the table is enough. The basis of everything is a sh-shaped iron transformer. I, depending on the need, rewind it without disassembling and without changing the primary.
What is a transformer for? The fact is that in order for the heater to work for some acceptable amount of time, the diameter of the wire must be as thick as possible. After analyzing this table, we can draw a disappointing conclusion - the wire should be as thick as possible. And this is no longer 220 volts.

Therefore, you will not find heaters designed for 220 volts in serious devices. Directly, if you connect this heater to the network, then the power consumption will be around 9 kW. You will plant a network throughout the house, and such a blow will be fatal for the heater. Therefore, voltage limiting circuits are used. For me, the most convenient is to use a transformer.
So, the primary: - 1.1 Volts per turn
- No-load current 450 mA
Secondary: - for a load of 5 ohms and a power of 1000 W, the voltage will be 70 Volts
- secondary current 14 A, wire 6 mm2, wire length 28 m.
Of course, this heater is not eternal. But I can replace it by finding a suitable wire and quickly rewinding the secondary.
If you read the instructions for Thermodat, then there is the possibility of limiting the maximum power. But this will not work for us, because we are talking about the average power per heater. In the mode of distributed pulses, as we have, the pulses will be for all 9 kW and we risk getting a pandemonium with light music. And on the neighbors too, because the machines in the entrance are also designed for average power.

For those who do not like to read instructions for a long time, I post a cheat sheet with coefficients and settings for a specific oven. After setting the Thermodata, turn on the trance and go.
The indicator of the current consumed from the network, due to the inertia of the arrow, also shows the average power. While the heater is cold, the current will be closer to 5 amps, as it warms up a little lower (due to the increase in heater resistance). As it approaches the setpoint, it will drop to almost zero (PID operation).

We load a full crucible with bronze scrap, close the lid. The lid is lined from the inside with fireclay lightweight on a mortar for fireplaces and stoves. For those who are especially curious (I myself am), there is a window covered with mica in the lid.

The temperature is over 1000, and the surface of the melter has not yet warmed up. This speaks volumes about the quality of the lining. After 30-40 minutes, the contents of the crucible melted.
After the end of melting, we press the elevator lever, after which we can already pick up the crucible with a grip. The photo shows a recess in the upper part of the crucible just for a secure grip.

P.S. About crucibles. YaSAM completes its furnaces with graphite crucibles that work with these heaters. If you work with gold and silver, it makes sense to buy them. But I am against these bourgeois excesses. The fact is that the F32/28 stainless pipe miraculously coincides with the diameter of the graphite crucible. Draw your own conclusion

We isolate the heater leads from the body with ceramic tubes. Ceramic tubes - from fuses, it is possible from resistors.

The top row of bricks is flush with the edge of the hull. Don't forget the hole for the elevator rod.

Third layer of lining. In this layer we make holes for the heater leads and for the thermocouple (pictured).

The second layer of lining. Cut for the upper output of the heater.

In induction furnaces, the metal is heated by currents excited in the non-variable field of the inductor. In essence, induction furnaces are also resistance furnaces, but differ from them in the way that energy is transferred to the heated metal. Unlike resistance furnaces, electrical energy in induction furnaces is first converted into electromagnetic energy, then again into electrical energy, and finally into thermal energy.

With induction heating, heat is released directly in the heated metal, so the use of heat is the most complete. From this point of view, these furnaces are the most advanced type of electric furnaces.

There are two types of induction furnaces: with a core and without a core, crucible. In core furnaces, the metal is in an annular trough around the inductor, inside of which the core passes. In crucible furnaces, a crucible with metal is located inside the inductor. It is impossible to use a closed core in this case.

Due to a number of electrodynamic effects that occur in the metal ring around the inductor, the specific power of channel furnaces is limited to certain limits. Therefore, these furnaces are mainly used for melting low-melting non-ferrous metals and only in some cases are used for melting and overheating cast iron in foundries.

The specific power of induction crucible furnaces can be quite high, and the forces resulting from the interaction of metal and inductor magnetic furnaces have a positive effect on the process in these furnaces, contributing to metal mixing.

How to assemble an induction furnace - diagrams and instructions

Coreless induction furnaces are used for smelting special, especially low-carbon steels and alloys based on nickel, chromium, iron, cobalt.

An important advantage of crucible furnaces is the simplicity of design and small dimensions. Thanks to this, they can be completely placed in a vacuum chamber and it is possible to process the metal with vacuum during the melting process. As vacuum steel-smelting units, induction crucible furnaces are becoming more and more widespread in the metallurgy of high-quality steels.

Figure 3. Schematic representation of an induction channel furnace (a) and a transformer (b)

Induction furnaces. Melting technology in induction furnaces

INDUCTION CRUCIBLE FURNACES.

Alloys of ferrous and non-ferrous metals and pure Me (cast iron, steel, bronze, brass, copper, and aluminum) are smelted in these furnaces. By current frequency: 1) Furnaces of industrial frequency 50 Hz. 2) Medium frequency up to 600 Hz. (up to 2400 Hz also included). 3) High frequency up to 18000Hz.

Often ind. ovens work in pairs (duplex process). In the first furnace, the mixture is melted, in the second, Me is brought to the desired chemical. composition or withstand Me at the desired t-re until the moment of pouring. The transfer of Mel from furnace to furnace can be carried out continuously along the chute using crane ladles or ladles on an electric car. In induction furnaces, the composition of the charge changes, instead of pig iron, lightweight low-quality materials are used (chips, lightweight scrap metal, waste from own production, i.e. trimmings).

Operating principle The charge is loaded into the crucible, variable el. the current passing through the inductor (coil) creates a magnetic field that induces an electromotive force in the metal cage, which is caused by induced currents, which cause heating and melting of Mel. Inside the coil there is a crucible made of refractory material, which protects the inductor from exposure to liquid Mel. The primary winding is an inductor. Secondary winding and at the same time load - Me-l in the crucible.

The efficiency of the furnace depends on the electrical resistance of Me-la and on the frequency of the current. For high efficiency, it is necessary that the diameter of the charge (d of the crucible) be at least 3.5-7 depths of current penetration in Me-l. Approximate ratios between the crucible capacity and the current frequency for steel and cast iron. The productivity of the furnaces is usually 30-40 t/h for cast iron and steel. With an electric power consumption of 500-1000 kWh / ton. For bronze, copper 15-22 t/h, for aluminum 8-9 t/h. Most often, a cylindrical crucible is used. The magnetic flux created by the inductor passes through closed lines both inside the inductor and outside.

Depending on the way the magnetic flux passes from the outside, there are: 1) open; 2) shielded; 3) closed oven design

With an open design, the magnetic flux passes through the air, so the structural elements (for example, the frame) are non-metallic or placed at a great distance from the inductor. When shielding, the magnetic flux from steel structures is separated by a copper screen. When closed - the magnetic flux passes through the radially arranged packages of transformer steel - magnetic circuits.

Scheme of the device of an electric induction furnace: 1 - cover, 2 turning unit, 3 - inductor, 4 - magnetic circuits, 5 - metal structure, 6 - water cooling inlets, 7 - crucible, 8 - platform

The furnace includes sl. nodes:Inductor, Lining, Frame, Magnetic circuits, Cover, Padina, Tilt mechanisms.

Aluminum Smelting Furnace

In addition to the main purpose, the inductor also performs the function of the element that perceives the fur. and thermal load from the side of the crucible. In addition, the cooling of the inductor ensures the removal of heat that occurs due to electrical losses, therefore, the inductors are made either in the form of a cylindrical single-layer coil, where all the turns are arranged in the form of a spiral with a constant angle of inclination, or in the form of a coil, all the turns of which are laid in a horizontal plane , and the transitions between them are in the form of short inclined sections.

Depending on the Me-la brand and the t-r level, 3 types of lining are used:

1. Sour(contains > 90% SiO2) withstands 80-100 melts

2. Main(up to 85% MgO) withstands 40-50 melts for small furnaces and up to 20 melts for furnaces with a capacity of >1 ton

3. Neutral(based on Al2O3 or CrO2 oxides)

Schemes of induction melting furnaces: a - crucible, b - channel; 1 - inductor; 2 - molten metal; 3 - crucible; 4 - magnetic core; 5 - a hearth stone with a heat release channel.

The padina is made of fireclay bricks for large ovens or aspot cement for small ones. Issue cover from structural steel and lined from the inside. Advantages of crucible furnaces:1) Intensive circulation of the melt in the crucible; 2) The ability to create an atmosphere of any type (oxidizing, reducing, neutral) at any pressure; 3) High performance; 4) Possibility of complete draining of Me-la from the oven; 5) Ease of maintenance, the possibility of mechanization and automation. Disadvantages: 1) Relatively low t-ra of slags induced on the Me-la mirror; 2) Relatively low durability of the lining at high melt t-p and in the presence of heat cycles.

INDUCTION DUCT FURNACES.

The principle of operation is that a variable magnetic flux permeates a closed circuit formed by liquid Chalk and excites a current in this circuit.

The contour of liquid Me-la is surrounded by a refractory material, which is baked into a steel case. The space filled with liquid Chalk has the shape of a curved channel. The working space of the furnace (bath) is connected to the channel by 2 holes, due to which a closed circuit is formed. During operation of the furnace, liquid Me-l moves in the channel and at the junctions with the bath. The movement is caused by Mel-la overheating (in the channel it is 50-100 ºС higher than in the bath), as well as by the influence of a magnetic field.

When all Mel is drained from the furnace, an electrical circuit breaks, which is created by liquid Mel in the channel. Therefore, in channel furnaces produce a partial discharge of liquid Me-la. The mass of the "swamp" is determined based on the fact that the mass of the column of liquid Mel above the channel exceeds the electrodynamic force pushing Mel out of the channel.

Channel furnaces are used as a mixer for holding and melting furnaces. The mixer is designed to accumulate a certain mass of Me-la and hold Me-la at a certain t-re. The capacity of the mixer is assumed to be at least twice the hourly output of the melting furnace. Dispensing ovens are used to pour liquid Me-la directly into molds.

Compared to crucible furnaces, channel furnaces have lower capital investments (50-70% of crucible furnaces), low specific power consumption (higher efficiency). Flaw: Lack of flexibility in chemical composition regulation.

The main nodes include: Furnace frame; lining; Inductor; Fur-zm tilt; Electrical equipment; Water cooling system.

The induction furnace is often used in the field of metallurgy, so this concept is well known to people who are more or less connected with the process of smelting various metals. The device allows you to convert electricity generated by a magnetic field into heat.

Such devices are sold in stores at a fairly high price, but if you have minimal skills in using a soldering iron and can read electronic circuits, then you can try to make an induction furnace with your own hands.

A homemade device is unlikely to be suitable for complex tasks, but it will cope with basic functions. You can assemble the device on the basis of a working welding inverter from transistors, or on lamps. The most productive in this case is the device on the lamps due to the high efficiency.

The principle of operation of the induction furnace

The heating of the metal placed inside the device occurs by the transition of electromagnetic pulses into heat energy. Electromagnetic impulses are produced by a coil with turns of copper wire or pipe.

Scheme of the induction furnace and heating schemes

When the device is connected, an electric current begins to pass through the coil, and an electric field appears around it, changing its direction over time. For the first time, the performance of such an installation was described by James Maxwell.

The object to be heated must be placed inside the coil or close to it. The target object will be pierced by a flux of magnetic induction, and a vortex-type magnetic field will appear inside. Thus, inductive energy will turn into heat.

Varieties

Furnaces on an induction coil are usually divided into two types depending on the type of construction:

• Channel;
• Crucible.

In the first devices, the metal for melting is located in front of the induction coil, and in the furnaces of the second type it is placed inside it.

You can assemble the oven by following the steps below:

1. We bend the copper pipe in the form of a spiral. In total, it is necessary to make about 15 turns, the distance between which should be at least 5 mm. Inside the spiral, a crucible should be freely located, where the smelting process will take place;
2. We make a reliable case for the device, which should not conduct electric current, and must withstand high air temperatures;
3. Chokes and capacitors are assembled according to the scheme indicated above;
4. A neon lamp is connected to the circuit, which will signal that the device is ready for operation;
5. A capacitor is also soldered to adjust the capacitance.

Heating use

Induction furnaces of this type can also be used for space heating. Most often they are used together with a boiler, which additionally produces cold water heating. In fact, designs are used extremely rarely due to the fact that, as a result of electromagnetic energy losses, the efficiency of the device is minimal.

Another drawback is based on the consumption of large amounts of electricity by the device during operation, because the device is classified as economically unprofitable.

System cooling

A self-assembled device must be equipped with a cooling system, since during operation all components will be exposed to high temperatures, the structure may overheat and break. Store-bought ovens are cooled with water or antifreeze.

When choosing a cooler for the home, preference is given to options that are most beneficial for implementation from an economic point of view.

For home ovens, you can try using a conventional blade fan. Pay attention to the fact that the device should not be too close to the oven, as the metal parts of the fan negatively affect the performance of the device, and can also open the vortex flows and reduce the performance of the entire system.

Precautions for using the device

When working with the device, you must adhere to the following rules:

• Some elements of the installation, as well as the metal that melts, are exposed to strong heat, as a result of which there is a risk of getting burned;
• When using a lamp oven, be sure to place it in a closed case, otherwise there is a high probability of electric shock;
• Before working with the device, remove all metal elements and complex electronic devices from the working area of ​​the device. The device should not be used by people who have a pacemaker installed.

The induction type metal melting furnace can be used in tinning and forming metal parts.

A home-made installation is easy to adjust to work in specific conditions by changing some settings. If you follow the indicated schemes when assembling the structure, as well as follow the elementary safety rules, a home-made device will practically not be inferior to store-bought household appliances.

A household induction stove can easily heat a home. In industry, these devices are involved in the smelting of various metals. Additionally, they can participate in the heat treatment of parts, as well as their hardening. The main advantage of an induction type oven is its ease of use. In addition, they are easy to maintain and do not require periodic inspections, which is very important.

There is absolutely no need to allocate a separate room for the installation of this device. The performance of these devices is very good. This is largely due to the fact that there are no parts in the design that are subject to mechanical wear. In general, induction-type furnaces are safe for human health and do not pose a danger during operation.

How it works?

The operation of the induction furnace begins with the supply of alternating current to the generator. At the same time, it passes through a special inductor, which is located inside the structure. Next, a capacitor is used in the device. Its main task is to form an oscillatory circuit. In this case, the entire system is tuned to the operating frequency. The inductor in the furnace creates an alternating magnetic field. At this time, the voltage in the device rises to 200 V.

To complete the circuit, the system has a ferromagnetic core, however, it is not installed on all models. Subsequently, the magnetic field interacts with the workpiece and creates a powerful flux. Next, the electrically conductive element is induced and a secondary voltage occurs. This creates an eddy current in the capacitor. According to the Joule-Lenz law, he gives his energy to the inductor. As a result, the workpiece in the furnace heats up.

Homemade induction type ovens

Do-it-yourself induction furnace is made strictly according to the drawings in compliance with safety rules. The body of the device should be selected from aluminum alloy. A large platform should be provided at the top of the structure. Its thickness must be at least 10 mm. Most often, a steel template is used to stuff the crucible. To drain the molten metal, a lining cavity in the form of a spout is required. In this case, the structure must have a pad for stuffing.

For sections, an insulating stand is installed above the template. Directly below it will be a hinged support. In order to cool the inductor, the furnace must have a fitting. Voltage is supplied to the device through the bridge, which is located at the bottom of the device. To tilt the container, a do-it-yourself induction furnace must have a separate gearbox. In this case, it is best to make a handle so that it is possible to merge the metal manually.

Furnaces of the company "Termolit"

Induction furnaces for melting metal of this brand have an acceptable converter power. At the same time, the capacity of the cameras in the models can vary greatly. The average metal melting rate is 0.4 t/h. At the same time, the nominal voltage of the supply network fluctuates around 0.3 V. The water consumption in an induction type furnace depends on the cooling system. Usually this parameter is 10 cubic meters / h. At the same time, the specific power consumption is quite high.

Characteristics of the furnace "Termolit TM1"

This melting furnace (induction) has a total capacity of 0.03 tons. At the same time, the converter power is only 50 kW, and the average melting speed is 0.04 tons per hour. The voltage of the supply medium must be at least 0.38 V. The water consumption for cooling in this model is negligible. This is largely due to the low power of the device.

Of the shortcomings, a high power consumption should be highlighted. On average, approximately 650 kW are consumed per hour of operation of the furnace. The frequency converter in this model has a class "TPCh-50". In general, "Termolit TM1" is an economical equipment, but with poor performance.

Induction furnace "TG-2"

Induction melting furnaces of the TG series are produced with a chamber capacity of 0.6 tons. The rated power of the device is 100 kW. At the same time, it is possible to melt 0.16 tons of non-ferrous metals per hour of continuous operation. This model is powered by a network with a voltage of 0.3 V.

The water consumption of the TG-2 furnace of the induction type is quite significant and, on average, up to 10 cubic meters of liquid is consumed per hour of operation. All this is due to the need for intensive cooling of the gearbox. The positive side is moderate power consumption. Typically, up to 530 kW of electricity is consumed per hour of operation. The frequency converter in the "TG-2" model is installed in the "TPCh-100" class.

Furnaces "Thermo Pro"

The main modifications of the equipment from this company are induction melting furnaces SAT 05, SAK-1, and SOT 05. Their average nominal melting point is 900 degrees. At the same time, the power of the devices fluctuates around 150 kW. In addition, it should be noted their good performance. For an hour of work of non-ferrous metals, 80 kg can be melted. At the same time, many Thermo Pro models are made for narrowly targeted use. Some of them are designed exclusively for working with aluminum, while other modifications are used to melt lead or tin.

Modification "SAT 05"

This induction furnace is designed for aluminum melt. The power of this device is exactly 20 kW. At the same time, up to 20 kg of metal can be passed per hour of work. The capacity of the chamber in the "SAT 05" model is 50 kg, and the frequency converter is of the "TFC" class.

Batteries in the device are installed capacitor type. In the lower part of the structure, the manufacturer installed a special water-cooled cable. The control panel in this model is available. Among other things, it should be noted a large set of furnace "SAT 05". It includes all mounting accessories, as well as operating documents.

Parameters of the furnace "SAK-1"

This induction furnace is most commonly used for melting lead as well as tin. In some cases, it is allowed to lay copper, but the performance drops significantly. The average melting temperature fluctuates around 1000 degrees, this device has a power of 250 kW. For an hour of continuous operation, it is possible to skip up to 400 kg of non-ferrous metals. At the same time, the capacity of the equipment allows loading up to 1000 kg of material. The supply voltage is 0.3 kV.

Water consumption for cooling the SAK-1 model is insignificant. The oven consumes approximately 10 cubic meters of liquid per hour. The specific power consumption is also small and amounts to 530 kW. The frequency converter in this design is provided for the brand "TPC-400". In general, the SAK-1 model turned out to be economical and easy to use.

Overview of the "SAK 05" model

Induction furnaces for melting metal "SAK 05" have a large capacity - 0.5 tons. At the same time, the power of the supply converter is 400 kW. The working speed of melting in this furnace is quite high. The rated voltage of the device is 0.3 kV. For an hour of water operation, approximately 11 cubic meters are consumed to cool the system. It should also be noted that the power consumption is considerable and amounts to 530 kW. The frequency converter in the device has a class "TPCh-400". At the same time, it is able to pump the maximum temperature up to 800 degrees. The induction furnace "SAK 05" is designed exclusively for melting aluminum and bronze. The heat exchange cabinet is installed by the manufacturer brand "IM". It should also be noted convenient remote control. There is an alarm system and a hydraulic station in the system.

Among other things, a set of turbo tires and mounting accessories are included as standard. In general, the SAK 05 model turned out to be quite secure, and you can use it without risk to health. This was largely achieved through rods that are mounted on hydraulic cylinders. At the same time, the metal practically does not splash. Direct frequency adjustment during operation occurs in automatic mode. Capacitors are used in this medium voltage model.

Induction furnaces are used for smelting metals and are distinguished by the fact that they are heated by means of electric current. The excitation of the current occurs in the inductor, or rather in a non-variable field.

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

• into the electromagnetic
• electrical;
• thermal.

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

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

In today's article we will talk about how to makeDIY induction oven.

Among the many benefits are the following:

• environmental cleanliness and safety;
• increased homogeneity of the melt due to the active movement of the metal;
• speed - the oven can be used almost immediately after switching on;
• zone and focused orientation of energy;
• high melting rate;
• lack of 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. Between the coil and the melting metal, the magnetic field dissipates, so a reduction in lining thickness will be required. This will soon lead to the fact that the lining itself will fail.

Video - Induction furnace

Industrial Application

Both design options are used in the smelting of iron, aluminium, steel, magnesium, copper and precious metals. The useful volume of such structures can range from several kilograms to several hundred tons.

Furnaces for 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, non-ferrous metals are also melted.
2. Industrial frequency designs are used in iron smelting.
3. Resistance structures are intended for melting aluminum, aluminum alloys, zinc.

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

domestic use

For obvious reasons, the induction melting furnace is rarely used in the home. But the technology described in the article is found in almost all modern houses and apartments. These are the microwaves mentioned above, and induction cookers, and electric ovens.

Consider, for example, plates. They heat the dishes due to inductive eddy currents, as a result of which the heating occurs almost instantly. It is characteristic that it is impossible to turn on the burner on which there are no dishes.

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

Homemade induction oven

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

Induction furnace from high frequency generator

Below is an electrical circuit for making a homemade device from a high-frequency (27.22 megahertz) generator.

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

Note! The main difference between the 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 manufacturing, it is necessary to remember some important points that affect the speed of metal boarding. This:

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

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

Video - Welding inverter design

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

Assembly technology

Step 1. The base is assembled - a box of fireclay bricks measuring 10x10x18 cm, laid on a refractory tile.

Step 2. Boxing is finished with asbestos cardboard. 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 is a transformer from a 0.63 kW welding machine. If the transformer is designed for 380 V, then it can be rewound, although many experienced electricians say that you can leave everything 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 suitable even 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 smelted at a time). For this reason, a different design will be required for melting large volumes.

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

Step 1. For the spiral, nichrome ø0.3 mm is used, about 11 m long.

Step 2. The wire must be wound. To do this, you need a straight copper tube ø5 mm - a spiral is wound on it.

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

Step 4. After checking the performance and the spiral is laid around the pipe. At the same time, the same asbestos thread is placed between the turns - it will prevent a short circuit and limit the access of oxygen.

Step 5. The finished coil is placed in a cartridge from a high power lamp. Such cartridges are usually ceramic and have the required size.

The advantages of such a design:

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

But there are, of course, downsides:

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

Note! You can not add metal to the stove if the previous portion is already melted there. Otherwise, all the material will scatter around the room, moreover, it may injure the eyes.

As a conclusion

As you can see, you can still make an induction furnace on your own. But to be frank, the described design (like everything available on the Internet) is not quite a furnace, but a Kukhtetsky laboratory inverter. It is simply impossible to assemble a full-fledged induction structure at home.