A domestic metal melting furnace can also be used to quickly heat up metal elements, for example, when they are tinned or shaped. The characteristics of the operation of the presented installations can be adjusted to a specific task by changing the parameters of the inductor and the output signal of the generator sets - this way you can achieve their maximum efficiency.

Ancient potters who fired pottery in kilns sometimes found shiny hard pieces with unusual properties at the bottom of the kilns. From the very moment when they began to think about what these wonderful substances were, how they appeared there, and also where they can be used with benefit, metallurgy was born - the craft and art of metal processing.

And the main tool for extracting new extremely useful materials from ore was thermosmelting forges. Their designs have come a long way of development: from primitive disposable clay domes heated by firewood to modern electric furnaces with automatic control of the melting process.

Metal-smelting units are needed not only by the giants of ferrous metallurgy, which use cupolas, blast furnaces, open-hearth furnaces and regenerator converters with a production of several hundred tons per cycle.
Such values ​​are typical for the smelting of iron and steel, which account for up to 90% of the industrial production of all metals.
In non-ferrous metallurgy and secondary processing, the volumes are much smaller. And the world turnover of production of rare earth metals is generally estimated at several kilograms per year.

But the need for smelting of metal products arises not only in its mass production. A significant sector of the metalworking market is occupied by foundry production, where metal-smelting units of relatively small output are required - from several tons to tens of kilograms. And for piece handicraft and arts and crafts production and jewelry, melting machines with a yield of several kilograms are used.

All types of metal-smelting devices can be divided according to the type of energy source for them:

1. Thermal. The heat carrier is flue gas or strongly heated air.
2. Electrical. Various thermal effects of electric current are used:
   • Muffle. Heating of materials placed in a heat-insulated housing with a spiral heating element.
   • resistance. Heating a sample by passing a large current through it.
   • Arc. The high temperature of the electric arc is used.
   • Induction. Melting of metal raw materials by internal heat from the action of eddy currents.
3. Streaming. Exotic plasma and cathode-ray devices.

In-Line Electron Beam Melting Furnace Thermal Open Hearth Furnace Electric Arc Furnace

With small volumes of generation, the most appropriate and economical is the use of electric, in particular, induction melting furnaces(IPP).

The device of induction electric furnaces

In short, their action is based on the phenomenon of Foucault currents - eddy induced currents in a conductor. In most cases, electrical engineers deal with them as a harmful phenomenon.
For example, it is precisely because of them that the cores of transformers are made of steel plates or tape: in a solid piece of metal, these currents can reach significant values, leading to useless energy losses for heating it.

In the induction melting furnace, this phenomenon is put to good use. In fact, it is a kind of transformer, in which the role of a short-circuited secondary winding, and in some cases the core, is played by a melted metal sample. It is metallic - only materials that conduct electricity can be heated in it, while dielectrics will remain cold. The role of the inductor - the primary winding of the transformer is performed by several turns of a thick copper tube rolled into a coil, through which the coolant circulates.

By the way, the extremely popular kitchen hobs with high-frequency induction heating operate on the same principle. A piece of ice placed on them will not even melt, and the set metal utensils will heat up almost instantly.

Design features of induction thermal furnaces

There are two main types of PPIs:

For both types of metal-smelting units, there are no fundamental differences in the type of working raw materials: they successfully melt both ferrous and non-ferrous metals. It is only necessary to select the appropriate operating mode and type of crucible.

Selection Options

Thus, the main criteria for choosing one or another type of thermal furnace are the volume and continuity of production. For a small foundry, for example, in most cases, a crucible electric furnace is suitable, and a channel furnace is suitable for a recycling company.

In addition, among the main parameters of a crucible thermal furnace is the volume of one heat, on the basis of which a specific model should be chosen. Important characteristics are also the maximum operating power and the type of current: single-phase or three-phase.

Choice of mounting location

The placement of the induction furnace in a workshop or workshop should provide a free approach to it for the safe performance of all technological operations in the melting process:

• loading of raw materials;
• manipulations during the working cycle;
• unloading of the finished melt.

The installation site must be provided with the necessary electrical networks with the required operating voltage and number of phases, protective earthing with the possibility of a quick emergency shutdown of the unit. Also, the installation must be provided with a supply of water for cooling.

Desktop structures of small dimensions must nevertheless be installed on strong and reliable individual bases not intended for other operations. Floor units also need to provide a solid reinforced foundation.

It is forbidden to place flammable and explosive materials in the melt discharge area. A fire shield with extinguishing agents must be hung near the location of the stove.

Installation instructions

Industrial thermomelting units are devices with high power consumption. Their installation and wiring must be carried out by qualified specialists. The connection of small units with a load of up to 150 kg can be carried out by a qualified electrician, following the usual rules for electrical installations.

For example, an IPP-35 furnace with a power of 35 kW with a production volume of ferrous metals of 12 kg, and non-ferrous metals - up to 40 has a mass of 140 kg. Accordingly, its installation will consist of the following steps:

1. Selection of a suitable location with a solid base for the hot melt unit and the water-cooled high voltage induction unit with capacitor bank. The location of the unit must comply with all operational requirements and regulations for electrical and fire safety.
2. Providing installation with a water cooling line. The described electric melting furnace does not come with cooling equipment, which must be purchased separately. The best solution for this would be a double circuit closed circuit cooling tower.
3. Protective earth connection.
   

   The operation of any electric melting furnace without grounding is strictly prohibited.

4. Connecting a separate electrical line with a cable, the cross section of which provides the appropriate load. The power shield must also provide the required load with a power margin

For small workshops and home use, mini-furnaces are produced, for example, UPI-60-2, with a power of 2 kW with a crucible volume of 60 cm³ for melting non-ferrous metals: copper, brass, bronze ~ 0.6 kg, silver ~ 0.9 kg, gold ~ 1.2 kg. The weight of the installation itself is 11 kg, dimensions - 40x25x25 cm. Its installation consists in placing it on a metal workbench, connecting flowing water cooling and plugging it into a power outlet.

Technology of use

Before starting work with a crucible electric furnace, it is imperative to check the condition of the crucibles and lining - internal protective thermal insulation. If it is designed for the use of two types of crucibles: ceramic and graphite, it is necessary to choose the appropriate loaded material according to the instructions.

Usually ceramic crucibles are used for ferrous metals, graphite - for non-ferrous.

Operating procedure:

• Insert the crucible inside the inductor and, having loaded the working material, cover it with a heat-insulating cover.
• Turn on water cooling. Many models of electric melting units will not start if there is not the necessary water pressure.

• The melting process in the crucible IPP begins with its inclusion and access to the operating mode. If there is a power regulator, set it to the minimum position before turning it on.
• Slowly raise the power to the working power corresponding to the loaded material.
• After melting the metal, reduce the power to a quarter of the working one to maintain the material in a molten state.
• Before pouring, turn the regulator to a minimum.
• At the end of melting - de-energize the installation. Turn off water cooling after it cools down.

All the time of melting the unit must be under supervision. Any manipulations with the crucibles should be done with tongs and in protective gloves. In the event of a fire, the installation should be immediately de-energized and the flames should be extinguished with a tarpaulin or extinguished with any fire extinguisher other than acid. Filling with water is strictly prohibited.

Advantages of induction furnaces

• High purity of the resulting melt. In other types of metal-melting thermal furnaces, there is usually direct contact of the heat carrier with the material, and, as a result, contamination of the latter. In IPP, heating is produced by absorption of the electromagnetic field of the inductor by the internal structure of the conductive materials. Therefore, such furnaces are ideal for jewelry production.
  

  For thermal furnaces, the main problem is to reduce the content of phosphorus and sulfur in the melts of ferrous metals, which worsen their quality.

• High efficiency of induction-melting devices, reaching up to 98%.
• High melting speed due to the heating of the sample from the inside and, as a result, high productivity of the IPP, especially for small working volumes up to 200 kg.
  

  Heating muffle electric furnace with a load of 5 kg occurs within a few hours, IPP - no more than an hour.

• Devices with a load of up to 200 kg are easy to place, install and operate.

The main disadvantage of electric melting devices, and induction devices are no exception, is the relative high cost of electricity as a coolant. But despite this, the high efficiency and good performance of the IPP largely pay for them during operation.

The video shows an induction furnace during operation.

Now furnaces with an induction system are widely used in the process of melting metals. The current produced in the field of the inductor contributes to the heating of the substance, and this feature of such devices is not only the main, but also the most important. Processing leads to the fact that the substance undergoes several transformations. The first stage of transformation is the electromagnetic stage, after it the electrical stage, and then the thermal stage. The temperature emitted by the stove is applied almost without a trace, so this solution is the best among all others. Many may be interested in the stove made. Next, we will talk about the possibilities of implementing such a solution.

Types of furnaces for melting metals

This type of equipment can be divided into main categories. At the first, the heart channel acts as a base, and the metal is placed in such furnaces in an annular way around the inductor. The second category has no such element. This type is called a crucible, and the metal is placed inside the inductor itself. In this case, it is technically impossible to use a closed core.

Basic principles

The melting furnace in this case works on the basis of the phenomenon of magnetic induction. And there are several components. The inductor is the most important component of this device. It is a coil, the conductors in which are not ordinary wires, but copper tubes. This requirement is set by the design of melting furnaces. The current that passes in the inductor generates a magnetic field that affects the crucible, inside of which the metal is located. In this case, the role of the secondary transformer winding is assigned to the material, that is, a current passes through it, heating it. This is how melting is carried out, even if an induction furnace is made by hand. How to build this type of furnace and increase its efficiency? This is an important question that has an answer. The use of increased frequency currents can significantly increase the degree of equipment efficiency. For this, it is appropriate to use special power supplies.

Features of induction furnaces

This type of equipment has certain characteristics that are both advantages and disadvantages.

Since the distribution of the metal must be uniform, the resulting material is characterized by a good homogeneous mass. This type of furnace works by transporting energy through zones, and the function of focusing energy is also provided. Parameters such as capacity, operating frequency and lining method are available for use, as well as regulation of the temperature at which the metal melts, which greatly facilitates the workflow. The existing technological potential of the furnace creates a high melting rate, the devices are environmentally friendly, completely safe for humans and ready to work at any time.

The most noticeable drawback of such equipment is the difficulty of cleaning it. Since the heating of the slag occurs solely due to the heat released by the metal, this temperature is not enough to ensure its full use. The high temperature difference between the metal and the slag makes it impossible to make the process of waste disposal as simple as possible. As another drawback, it is customary to highlight the gap, due to which it is always necessary to reduce the thickness of the lining. Due to such actions, after a while it may turn out to be faulty.

The use of induction furnaces on an industrial scale

In industry, crucible and channel induction furnaces are most common. In the first, any metals are smelted in arbitrary quantities. Tanks for metal in such variants are able to fit up to several tons of metal. Of course, do-it-yourself induction melting furnaces in this case cannot be done. Channel furnaces are designed for smelting non-ferrous metals of various types, as well as cast iron.

Fans of radio engineering and radio technologies are often interested in this topic. Now it becomes clear that creating induction furnaces with your own hands is quite realistic, and a lot of people managed to do it. However, to create such equipment, it is required to implement the action of an electrical circuit that would contain the prescribed actions of the furnace itself. Such solutions require the involvement of those capable of producing wave oscillations. A simple do-it-yourself induction furnace according to the scheme can be built using four electronic lamps in combination with one neon, signaling that the system is ready to go.

In this case, the AC capacitor handle is not placed inside the instrument. Thanks to this, a do-it-yourself induction furnace can be created. The device diagram describes in detail the location of each individual element. You can make sure that the device is powerful enough if you use a screwdriver, which should reach a hot state in just a few seconds.

Peculiarities

If you are creating an induction furnace with your own hands, the principle of operation and assembly of which is studied and carried out according to the appropriate scheme, you should know that one or more of the factors listed below can affect the melting rate in this case:

Pulse frequency;

Hysteresis losses;

Generator power;

The period of heat release to the outside;

Losses associated with the occurrence of eddy currents.

If you are going to do an induction oven with your own hands, then when using lamps, you need to remember that their power should be distributed so that four pieces are enough. When using a rectifier, you get a network of approximately 220 V.

Domestic use of stoves

In everyday life, such devices are used quite rarely, although similar technologies can be found in heating systems. They can be seen in the form of microwave ovens and in the environment of new technologies, this development has found wide application. For example, the use of eddy currents in induction cookers allows you to cook a huge variety of dishes. Since they take very little time to warm up, the burner cannot be turned on if there is nothing on it. However, special cookware is required to use such special and useful stoves.

Assembly process

Do-it-yourself induction consists of an inductor, which is a solenoid made from a water-cooled copper tube and a crucible, which can be made of ceramic materials, and sometimes steel, graphite and others. In such a device, it is possible to smelt cast iron, steel, precious metals, aluminum, copper, magnesium. Do-it-yourself induction furnaces are made with a crucible capacity from a couple of kilograms to several tons. They can be vacuum, gas-filled, open and compressor. Furnaces are fed with currents of high, medium and low frequency.

So, if you are interested in a do-it-yourself induction furnace, the scheme involves the use of such basic components: a melting bath and an induction unit, which includes a hearth stone, an inductor and a magnetic core. The channel furnace differs from the crucible one in that the electromagnetic energy is converted into thermal energy in the heat release channel, in which there must always be an electrically conductive body. To make the initial start-up of a channel furnace, molten metal is poured into it or a template is inserted from a material that can be cracked down in the furnace. When the melt is completed, the metal is not completely drained, but a "swamp" is left, designed to fill the heat release channel for future start-ups. If you are going to do-it-yourself induction furnace, then to facilitate the replacement of the hearth stone for equipment, it is made detachable.

Furnace components

So, if you are interested in a do-it-yourself induction mini-oven, then it is important to know that its main element is a heating coil. In the case of a homemade version, it is enough to use an inductor made of a bare copper tube with a diameter of 10 mm. For the inductor, an inner diameter of 80-150 mm is used, and the number of turns is 8-10. It is important that the turns do not touch, and the distance between them is 5-7 mm. Parts of the inductor must not come into contact with its screen, the minimum clearance must be 50 mm.

If you are going to do-it-yourself induction furnace, then you should know that water or antifreeze is cooling the inductors on an industrial scale. In the case of low power and short operation of the created device, it is possible to do without cooling. But during operation, the inductor becomes very hot, and scale on copper can not only drastically reduce the efficiency of the device, but also lead to a complete loss of its performance. It is impossible to make an inductor with cooling on your own, so it will need to be replaced regularly. Forced air cooling must not be used, since the fan housing located close to the coil will “attract” EMF to itself, which will lead to overheating and a decrease in the efficiency of the furnace.

Generator

When a do-it-yourself induction furnace is assembled, the circuit involves the use of such an important element as an alternator. You should not try to make a stove if you do not know the basics of radio electronics at least at the level of an average radio amateur. The choice of the oscillator circuit must be such that it does not give a hard current spectrum.

Use of induction furnaces

This type of equipment has become widespread in areas such as foundries, where the metal has already been cleaned and needs to be given a specific shape. You can also get some alloys. In jewelry production, they also became widespread. The simple principle of operation and the possibility of assembling an induction furnace with your own hands make it possible to increase the profitability of its use. For this area, devices with a crucible capacity of up to 5 kilograms can be used. For small productions, this option will be optimal.

Aluminum alloys have low melting point and good machinability details. And on the farm there is always a lot of aluminum scrap.

Therefore, aluminum is often melted at home to replace non-standard or small parts of mechanisms: a blank is cast, and then processed on a lathe. Sometimes souvenirs and small interior items are made from aluminum with their own hands.

Melting furnace device

Homemade aluminum melting furnaces consist of a body - metal cylinder (2), lined with refractory (chamotte with sand or concrete). Inside the mine is charcoal (8) serving as fuel. It is installed crucible (3)- a container in which the metal will be melted. The crucible can be a thick tin can, teapot or any stainless steel container.

At the bottom of the mine (6) made air inlet (7) through lattice base (4), which allows you to maintain combustion and regulate the temperature in the furnace.

A hair dryer or vacuum cleaner pipe is used as a supercharger. Flap (5) needed to remove excess air.

For furnaces with a capacity of several tens of kilograms, cover (1) for fast and uniform heating of metal. In small ovens, you can do without it.

Furnace elements should not deform and melt when heated. Therefore, the use of aluminum cases, tubes and crucibles is unacceptable. It is best to take to build a structure steel or cast iron details.

Reference. Also used as a fuel for aluminum smelting natural gas or electricity.

How to make a furnace for melting metal?

Creating a small unit that allows you to melt a few kilograms of aluminum scrap is a simple task. For laying out the oven in the garden you will need the following materials:

• red bricks - 20-25 pcs.;
• high tin can - 1 pc.;
• grill grate — 1 pc.;
• drying hair dryer - 1 pc.;
• piece of pipe, in diameter suitable for the outlet of the hair dryer - 1 PC.;
• roll of electrical tape;
• line segment steel wire long 30-50 cm;
• coal for ignition (the amount depends on how much aluminum needs to be melted).

The bricks will be both housing, and fireproof coating furnace, a tin can will act as a crucible. At the top of the jar are made two holes opposite each other, and through them wire is threaded. For it it will be possible to lift and pull out the crucible with the melt from the furnace. Air will be supplied from the dryer switched on in the cold air mode. To the outlet of the hair dryer, you need to tape or tape wrap a piece of pipe- this will be the air duct.

Such simple circuit The furnace is convenient in that tools for its creation are actually not required, everything is done by hand.

Important! Do not use elements with zinc coated, because when melting aluminum, toxic zinc fumes will be released.

Brick well installation plan

1. Giving all the best one row bricks in the form of a rectangular well. The internal dimensions of the hole should be approx. length and width of one brick. On one side two bricks laid out so as to form a corridor for the duct. The width of the corridor is tube diameter for air supply.
2. On lined row grating is installed. Instead of a grill grate, you can use any metal cover or plate with holes for air supply.
3. Laid out on the grid second row bricks, already without a gap for the duct.

Photo 1. Finished brick well for the melting furnace. The edges are reinforced with metal strips, the air duct opening is visible.

1. Created duct. To the hair dryer with tape or electrical tape a piece of pipe is attached. To ensure the strength of the structure, the junction wrapped in thick paper and then connects duct tape. Insulating tape is a more elastic material compared to adhesive tape, so it is more convenient to work with it. Also, the button for supplying cold air is fixed with tape on the hair dryer. Ready the mechanism is brought to the bottom row bricks.
2. In the furnace well on the grate poured and melted coal for ignition. The hair dryer is turned on, which activates the combustion process.

Advice. The air flow rate can be adjusted by changing hair dryer mode, as well as distance between pipe and window for air duct.

1. Tin installed to the top row bricks for the wire threaded into it. Like a pot over a fire, it hangs over a grate.
2. After kindling the furnace and installing the crucible third row are placed two more bricks so as to get a square hole from a rectangular hole. This will fix the jar inside the case and heat up the oven space faster.

After heating the jar into it scrap can be loaded for meltdown. A sign of warming up the jar is its redness.

The principle of the device and operation of such a furnace is very simple and does not cause difficulties. However, you should always remember safety precautions:

• work in fireproof gloves;
• avoid getting water into the melt;
• do not use materials containing toxic substances.

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Two can design

Another type of homemade aluminum melting furnace is the design of two large jars. One of them serves corps, in which a hole is cut for air supply, and bottom second cans with holes serves as a divider.

A crucible is placed inside the jars.

Such an apparatus very compact, and small amounts of metal can be melted even in a ventilated garage. However, the design does not differ in stability and fire resistance and will last only a few cycles.

Possible problems and solutions

Carelessly assembled apparatus causes the oven to operate inefficiently and makes it dangerous to use. Here are a few points to pay attention to:

• Cracks and gaps in a brick building. They can be formed by chips on bricks or loose fit of refractories to each other. The gaps reduce the efficiency of the fuel, reduce the intensity and temperature of combustion. Aluminum in the crucible may simply not melt.

Therefore, after laying out each row, a visual check for the presence of holes is carried out. holes smeared with sand-clay mixture or covered with refractory material.

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It is recommended to use a concrete solution only in the case of a stationary unit that is not planned to be disassembled. But asbestos sheets and chips should not be used in places where the furnace is heated, because this material is a carcinogen.

• Level violation the buildings. Skewness reduces the stability of the structure and creates conditions for uneven distribution of coal. As a result - uneven heating of the crucible and the metal in it.

Laying out each, especially the bottom row of bricks level controlled. You can also check the horizontality placing a jar of water on the grate. On a flat surface, the top edge of the water will be parallel to the edge of the can.

For a long time, men began to think about how to create their own furnace for melting metal at home. It must be portable and meet all conditions. Furnaces for melting a large amount of metal are installed at the production facility. At home, you can assemble a furnace for melting up to five kilograms of aluminum. Consider how to make a smelter at home.

Equipment and materials you will need

In order to smelt metal, you need to buy the following components for manufacturing:

• refractory brick;
• nails;
• transformer;
• copper wire;
• graphite;
• mica;
• asbestos and cement tiles;
• gas-burner;
• crucible.

Dimensions will vary from the desire of the person who collects it. It is better to create a small furnace for melting metals if you want to use it only for your own needs. You will spend less time on its manufacture, and a small number of kilowatts will be spent on heating it. If you are doing it on diesel fuel or on coal, then do not forget about installing thermal insulation and air blowing.

Metals such as iron, nickel, tin, copper are melted in an electric furnace. The output voltage in the electric furnace should be greater, which means that the distance between the electrodes will increase. Brushes from an electric motor are suitable instead of electrodes.

Step-by-step instruction

How to make a melting furnace at home - read the following instructions:

• A high-frequency alternator is installed.
• Spiral winding. Made from copper wire.
• Crucible.

All these elements are placed in one case. The melting cup is placed in the inductor. The winding is connected to a power source. When the current is turned on, an electromagnetic field appears. The resulting eddy currents pass through the metal in the cup and heat it. Melting occurs.

The positive properties of an induction furnace are that during the remelting of metals a homogeneous melt is obtained, alloying components do not evaporate, and melting occurs rather quickly. In addition, the installation of such a furnace does not harm the ecosystem and is safe for those who use it.

Cooling can be done with a fan. Only the latter should be located as far as possible from the furnace, otherwise its winding will serve as an additional closure of vortex flows. This will reduce the quality of the melt.

Features of melting of some metals

In order to melt metal at home, this element must be placed in a small cup or crucible. The cup with the material is inserted into the oven. Then his melting begins. To melt precious elements, they are placed in a glass ampoule. In order to make an alloy of several components, follow these instructions:

• First, a refractory element - copper or iron - is placed in a cup for melting.
• Then a more fusible component is placed - tin, aluminum.

Steel is a refractory material. Its melting point is one thousand four hundred degrees Celsius. Therefore, in order to melt steel at home, you must follow the following instructions:

• To melt steel at home, introduce additional regenerators. If the stove is powered by electricity, then electricity is used.
• During induction heating, slags are added. They increase the speed of melting.
• Constantly monitor instrument readings. If necessary, lower the melting temperature, switching to a more moderate mode.
• It is always correct to determine whether the steel is ready for work or for melting. Follow all of the above steps. Only then will the output metal be of high quality.

To melt iron at home, the furnace must be preheated. First, a large piece is placed, and then small ones. Iron must be turned over in time. A properly molten metal will have a spherical shape.

If you are going to make bronze, then you first need to place copper in the melting hole. Since this component is more refractory. When copper is melted, tin is added.

Under no circumstances should elements such as cadmium, lead or zinc be melted. When burnt out, they form a poisonous yellowish smoke.

And when melting aluminium, tin or iron, it is necessary to observe slowness. Rivet slowly and do this with a small hammer. Frequently heat material until red and cool in cold water. Only then will you get the perfect alloy at the end.