DIY mini melting furnace. Tin cans and other scrap are recyclable! How to make a furnace for melting aluminum with your own hands

A furnace for melting metals at home can also be used to quickly heat metal elements, for example, when tinning or forming them. The operating characteristics of the presented installations can be adjusted to a specific task by changing the parameters of the inductor and the output signal generator sets- this is how you can achieve their maximum efficiency.

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

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

The process of making a homemade melting furnace

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

Materials and tools:

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

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

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

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

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

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

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

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

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

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

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

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How to make a transformer?

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

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

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

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

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

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

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How is metal melted in a furnace?

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

If the pieces of metal to be melted have various sizes, then first of all they lay big piece. After it melts, add small pieces.

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

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

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

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

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

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

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

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

If you have a need for annealing metals, creating ceramics, melting non-ferrous materials, etc. precious metals, you can build yourself such a simple oven. Most of these stoves cost a lot of money; according to the author, in his region prices are in the region of $600-12,000 per stove. In our case, the oven cost only $120, not counting the temperature controller. This small oven can produce temperatures around 1100 o C.

The homemade product is easy to assemble, all the parts are not expensive, and they can also be quickly replaced if the stove malfunctions.

Some craftsmen manage to make in such ovens wedding rings, various talismans, brass knuckles and much more.

Materials and tools for homemade work:

Materials:
- bolts and nuts (8x10, 1/4 inch);
- seven fire bricks (they must be soft as they will need to be grooved, dimensions 4 1/2" x 9" x 2 1/2");
- corner for creating a frame;
- a square sheet of metal for the door (the author used aluminum);
- heating element (you can buy ready-made spirals for the oven, or wind your own from nichrome)
- heat-resistant contact screws for fastening the spiral;
- a piece of good cable (must withstand at least 10A).

From the tools:
- hand drill with a suitable attachment for cutting grooves in brick;
- wrench;
- pliers;
- hacksaw;
- drill;
- wire cutters and more.

The process of making a homemade stove:

Step one. Making grooves
First you need to decide how wide the spiral is; depending on this, the depth and width of future grooves in the bricks are determined. Next, you need to draw them on the brick with a pencil. The author’s grooves are shaped like the letter “U”; there are two grooves of this shape in total, that is, they are cut out on two bricks. On the brick that will be located at the back of the stove, you need to make two parallel grooves as in the photo. As a result, after assembling the furnace, the spiral will receive approximately a “U”-shape.

Well, then you can lay the stove in the groove. To fix the spiral, the author uses metal brackets, for which holes will need to be made in the brick. Special attention You need to pay attention to connecting the spiral to the wire. Here special screws with ceramic washers must be used, and the screws must be longer. Otherwise, the wire insulation will either constantly burn and stink, or it will constantly burn due to the high temperature.

Our people learned to make such contacts from old car spark plugs when the ancient open-coil electric hot plates were used.

Particular attention should be paid to the choice of material from which the spiral is made. It will depend on this Maximum temperature, which the oven can produce. The spiral must withstand high temperature loads. For such purposes, the author chose a NiCr type wire. Most of such wires are designed for temperatures of about 1340 o C. If you require higher temperatures, then you can choose other types of wires that are suitable for this.

Step three. Making the stove frame
To create a frame you will need a corner; you can use steel or aluminum. Four pieces of aluminum form the legs, and two more go to the bottom to support the weight of all the bricks. You can use not two corners, but four, to create the lower support. However, this is not necessary; in the end, the structure is still tightened with bolts and nuts, these bolts hold the bricks down.

In the upper part of the stove you will need to lay two or one and a half bricks, as well as below. Well, you can see in detail how everything is assembled in the photo.

The car used Kaowool plate as a fireproof material. It needs to be cut to the size of the previously drawn square. Well, then the slab is laid on the sheet, and the remaining edges of the sheet are folded, thereby holding the slab.

Step five. We supply electricity
To connect the spiral you need to use good wire with a thick core that can withstand at least 10A. Among other things, the oven is connected through a regulator, which will allow you to maintain the temperature in the desired state. You will also need a stove thermometer, which will help you more accurately monitor the temperature in the stove.

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

Induction furnace structure

The oven consists of 3 elements:

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

In order to assemble a working furnace for melting metal, it is enough to assemble a working electrical diagram and an inductor cooling system. The simplest version of metal melting is shown in the video below. Melting is carried out in the counter electromagnetic field of the inductor, which interacts with induced electro-eddy currents in the metal, which holds a piece of aluminum in the space of the inductor.

In order to effectively melt metal, large currents and high frequencies of the order of 400-600 Hz are required. The voltage from a regular 220V home socket is sufficient to melt metals. It is only necessary to turn 50 Hz into 400-600 Hz.
Any circuit for creating a Tesla coil is suitable for this. I liked the following 2 circuits on the GU 80, GU 81(M) lamp the most. And the lamp is powered by an MOT transformer from a microwave oven.

These circuits are intended for a Tesla coil, but they make an excellent induction furnace; instead of the secondary coil L2, it is enough to place a piece of iron in the internal space of the primary winding L1.

The primary coil L1 or inductor consists of a copper tube rolled into 5-6 turns, the ends of which are threaded to connect the cooling system. For levitation melting, the last turn should be done in the opposite direction.
Capacitor C2 in the first circuit and an identical one in the second sets the frequency of the generator. At a value of 1000 picoFarads, the frequency is about 400 kHz. This capacitor must be a high-frequency ceramic capacitor and designed for high voltage of about 10 kV (KVI-2, KVI-3, K15U-1), other types are not suitable! It's better to use K15U. Capacitors can be connected in parallel. It is also worth taking into account the power for which the capacitors are designed (this is written on their case), take it with a reserve. the other two capacitors KVI-3 and KVI-2 heat up at long work. 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 is a schematic diagram of what should happen. I circled 3 blocks in frames.

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

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

And the main tool for extracting new ore from ore is extremely useful materials steel thermomelting forges. Their designs have come a long way in development: from primitive disposable clay domes heated with wood to modern electric furnaces with automatic control melting process.

Metal-smelting units are needed not only by the giants of the ferrous metallurgy industry, which use cupola furnaces, blast furnaces, open-hearth furnaces and regenerative 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% industrial production all metals.
In non-ferrous metallurgy and recycling, the volumes are much smaller. And the global turnover of production of rare earth metals is generally calculated at several kilograms per year.

But the need for melting metal products arises not only during their mass production. A significant sector of the metalworking market is occupied by foundry production, which requires metal-smelting units of relatively small output - from several tons to tens of kilograms. And for piece craft, arts and crafts production and jewelry making, melting machines with a production capacity 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 coolant is flue gas or highly heated air.
2. Electrical. Use various thermal effects electric current:
   • Muffle. Heating of materials placed in a thermally insulated housing with a spiral heating element.
   • Resistance. Heating a sample by passing a large current through it.
   • Arc. Use high temperature electric arc.
   • Induction. Melting metal raw materials internal heat from the action of eddy currents.
3. Streaming. Exotic plasma and electron beam devices.

Flow electron beam melting furnace Thermal open hearth furnace Electric arc furnace

For small production volumes, the most expedient and economical is the use of electric ones, especially induction melting furnaces (IPP).

Construction of induction electric furnaces

In short, their action is based on the phenomenon of Foucault currents - eddy induction currents in a conductor. In most cases, electrical engineers deal with them as a harmful phenomenon.
For example, it is because of them that transformer cores 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 an induction melting electric furnace, this phenomenon is used to advantage. In essence, 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 molten 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 kitchen appliances that have become extremely popular operate on the same principle. hobs with induction high frequency heating. A piece of ice placed on them will not even melt, but placed 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 crucible type.

Selection options

Thus, the main criteria for choosing one or another type of thermal furnace are volumes 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 plant.

In addition, one of the main parameters of a crucible hot furnace is the volume of one melt, based on which you should choose specific model. Important characteristics are also the maximum operating power and the type of current: single-phase or three-phase.

Choosing a location for installation

The location of the induction furnace in a workshop or workshop should provide free access to it for the safe performance of all technological operations during the smelting process:

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

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

Tabletop structures of small dimensions must nevertheless be installed on strong and reliable individual bases not intended for other operations. Floor-standing units also need to be provided with a solid, reinforced foundation.

It is prohibited to place fire and explosive materials in the melt unloading 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 energy consumption. Their installation and electrical installation must be carried out qualified specialists. Connection of small units with a load of up to 150 kg can be carried out by a qualified electrician in compliance with normal rules installation of electrical installations.

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

1. Choice suitable place accommodation with a solid foundation for thermomelting unit and high-voltage water-cooled induction unit with capacitor bank. The location of the unit must comply with all operational requirements and electrical and fire safety regulations.
2. Providing the installation with a water cooling line. The described electric melting furnace does not include cooling means in the delivery set, which must be purchased additionally. The best solution it will have a double-circuit closed-cycle cooling tower.
3. Connection of protective grounding.
   

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

4. Supplying a separate electrical line with a cable whose cross-section provides the appropriate load. The power shield must also provide the required load with a power reserve

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 are 40x25x25 cm. Its installation consists of placing it on metal workbench, connecting flow water cooling and plugging it into a power outlet.

Technology of use

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

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

Operating procedure:

• Insert the crucible inside the inductor and, after loading it with the working material, cover it with a heat-insulating lid.
• Turn on water cooling. Many models of electric melting units will not start if not required pressure water.

• The melting process in a crucible IPP begins with its switching on and entering the operating mode. If there is a power regulator, set it to the minimum position before turning it on.
• Smoothly increase the power to operating power corresponding to the loaded material.
• After melting the metal, reduce the power to a quarter of the working power to maintain the material in a molten state.
• Before spilling, turn the regulator down to minimum.
• Upon completion of melting, turn off the power to the installation. Turn off water cooling after it has cooled down.

The unit must be under supervision throughout the melting process. Any manipulations with crucibles must be done using tongs and wearing protective gloves. In the event of a fire, the installation should be immediately de-energized and the flames should be knocked out 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-smelting thermal furnaces, there is usually direct contact of the coolant with the material, and, as a result, contamination of the latter. In IPP, heating is produced by the 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 reducing the content of phosphorus and sulfur in ferrous metal melts, which deteriorate their quality.

• High efficiency of induction melting devices, reaching up to 98%.
• High melting speed due to 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 up of an electric muffle furnace with a load of 5 kg occurs within several hours, while the IPP takes no more than an hour.

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

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

The video shows an induction oven in operation.