Furnace for heating lead metal diagram. Homemade furnace for melting and hardening metal at home

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

That's why 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 structure

Homemade furnaces for melting aluminum consist of a body - metal cylinder (2), lined with refractory (clamotte 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 melt. The crucible can be a thick tin can, a teapot or any stainless steel container.

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

A hair dryer or a vacuum cleaner pipe is used as a blower. Damper (5) necessary to remove excess air.

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

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

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

How to make a furnace for melting metal?

Creating a small unit that can melt several kilograms of aluminum scrap is not a difficult task. To lay out the stove in the garden you will need following materials:

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

The bricks will appear simultaneously and body and fireproof coating oven, a tin can will act as a crucible. At the top of the can are being done two holes opposite each other, and through them the wire is threaded. It will be possible to lift and remove the crucible with the melt from the furnace. The air will be supplied from the hairdryer turned on in cold air mode. Tape or tape to the outlet of the hair dryer attach a piece of pipe- this will be the air duct.

Such simple circuit The furnace is convenient in that no tools are actually required to create it; everything is done by hand.

Important! Do not use oven elements with zinc coating, because when aluminum is melted, toxic zinc fumes will be released.

Brick well installation plan

Gives his all one row bricks in the form of a rectangular well. The internal dimensions of the hole should be approximately length and width of one brick. On one side two bricks laid out so as to form a corridor for the air duct. The width of the corridor is tube diameter for air supply.
On the laid out row grating is installed. Instead of a grill grate, you can use any metal lid or plate with holes for air supply.
Placed on the grill second row bricks, without any gap for the air duct.

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

Created air duct. Tape or tape to the hairdryer a piece of pipe is wound. To ensure structural strength, the connection point wrapped in thick paper, and then connects duct tape. Electrical tape is a more elastic material compared to adhesive tape, so it is more convenient to work with. The cold air supply button is also secured with tape on the hairdryer. Ready the mechanism is brought to the bottom row bricks.
In the stove well on the grate coal is poured and melted for ignition. The hair dryer turns on, which activates the combustion process.

Advice. The air supply intensity can be adjusted by changing hair dryer operating mode, and distance between pipe and window for the air duct.

Tin is installed to the top row bricks for the wire threaded into it. Like a pot over a fire, it hangs over the grate.
After lighting the furnace and installing the crucible third row are placed two more bricks so that from a rectangular hole you get a square one. This will fix the can inside the housing and heat up the oven space faster.

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

The principle of the design and operation of such a furnace is very simple and does not cause difficulties. However, it is always worth remembering safety precautions:

work in fire-resistant gloves;
avoid water getting into the melt;
do not use materials containing toxic substances.

Two-can design

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

A crucible is installed inside the jars.

Such a device very compact, and small volumes of metal can be melted even in a ventilated garage. However, the design is not resistant or fire resistant, and will only last a few cycles.

Possible problems and their solutions

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

Slots and gaps in a brick building. They can be caused by chips on bricks or loose fit of refractories to each other. Gaps reduce fuel efficiency and reduce combustion intensity and temperature. Aluminum in a crucible may simply not melt.

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

It is recommended to use concrete mortar 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 stove is heated, because this material is a carcinogen.

Violation of the horizontal level the buildings. Misalignment reduces the stability of the structure and creates conditions for uneven distribution of coal. The result is uneven heating of the crucible and the metal in it.

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

A muffle furnace for melting or hardening metal products is a device that allows a home craftsman to perform certain work. A simple unit that can operate on different types of fuel; for self-production, it is enough to have the skills to perform plumbing and electric welding work.

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Device and circuit

The structure of a muffle furnace for metal melting consists of:

in most cases a steel body. For home use, it is better to make it from heat-resistant metal or stainless steel. But you can use structural steel. Sheet thickness 1.5-2 mm;
layer of internal thermal insulation. For home stoves, fireclay brick or other heat-insulating material is used that can withstand heating temperatures up to 1000 0 - 1200 0;
the steel body can be lined with an outer layer of ceramic tiles or refractory bricks;
electric or gas heating elements. It is better to purchase gas burners in specialized stores. An electric oven can be equipped with homemade spirals made of nichrome or fechral. Wire thickness – 1 mm. Fechral wire is cheaper, but it is inferior to nichrome in terms of resistance to aggressive environments and the durability of the spiral;
system of automatic or manual control of equipment operation. By installing thermal sensors, you can easily control the temperature and the time to maintain the set temperature.

Conclusion

Homemade or industrial furnaces for hardening metal or melting it - all these designs should ensure safety and comfort in working with heating devices. It’s not difficult to make the design yourself; even a beginner can do it. The main thing is to carefully and responsibly follow all recommendations and rules for performing work.

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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. The production facility has furnaces for melting large quantities of metal. At home, you can assemble a furnace for melting up to five kilograms of aluminum. Let's look at how to make a smelter at home.

Equipment and materials you will need

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

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

The dimensions will vary depending on the wishes of the person collecting it. It is better to create a small furnace for melting metals if you want to use it only for your needs. You will spend less time making it, and a small amount of kilowatts will be spent heating it. If you do it using diesel fuel or coal, then do not forget about installing thermal insulation and air supply.

Metals such as iron, nickel, tin, and copper are melted in an electric furnace. The output voltage in an electric furnace should be greater, which means 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 alternating current generator is installed.
Spiral winding. Made from copper wire.
Crucible.

All these elements are placed in one housing. The melting cup is placed in the inductor. The winding is connected to the 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 when melting metals, a homogeneous melt is obtained, alloying components do not evaporate, and melting occurs quite quickly. In addition, the installation of such a stove does not harm the ecosystem and is safe for the user.

Cooling can be done using 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 the vortex flows. This will reduce the melting quality.

Features of melting 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 its melting begins. To melt the precious elements, they are placed in a glass ampoule. In order to make an alloy from several components, follow these instructions:

First, a refractory element - copper or iron - is placed in the melting cup.
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, to melt steel at home, you must follow the following instructions:

To melt steel at home, introduce additional regenerators. If the furnace runs on 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 by switching to a more moderate mode.
It is always correct to determine whether the steel is ready for work or melting. Follow all the above steps. Only then will the resulting 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, you must first place copper in the melting hole. Since this component is more refractory. When the copper is melted, tin is added.

Under no circumstances should elements such as cadmium, lead or zinc be melted. When burned, they produce toxic yellowish smoke.

And when melting aluminum, tin or iron, you must be careful. Rivet slowly and should be done with a small hammer. Heat the material frequently until reddened and cool in cold water. Only then will you get the perfect alloy at the end.

An induction furnace is used for melting non-ferrous and ferrous metals. Units of this operating principle are used in the following areas: from the finest jewelry making to large-scale industrial smelting of metals. This article will discuss the features of various induction furnaces.

Induction furnaces for metal melting

Principle of operation

Induction heating is the basis for the operation of the furnace. In other words, electric current creates an electromagnetic field and heat is obtained, which is used on an industrial scale. This law of physics is studied in the last grades of secondary school. But the concept of an electric unit and electromagnetic induction boilers should not be confused. Although the basis of work here and there is electricity.

How does this happen

The generator is connected to an alternating current source, which enters it through an inductor located inside. The capacitor is used to create an oscillation circuit, which is based on a constant operating frequency to which the system is tuned. When the voltage in the generator increases to a limit of 200 V, the inductor creates an alternating magnetic field.

The circuit is closed, most often, through a ferromagnetic alloy core. The alternating magnetic field begins to interact with the workpiece material and creates a powerful flow of electrons. After the electrically conductive element enters into inductive action, the system experiences occurrence of residual stress, which in the capacitor contributes to the occurrence of eddy current. The energy of the eddy current is converted into thermal energy of the inductor and the desired metal is heated to high melting temperatures.

The heat produced by the inductor is used:

for melting soft and hard metals;
for hardening the surface of metal parts (for example, tools);
for thermal treatment of already produced parts;
household needs (heating and cooking).

Brief characteristics of various furnaces

Types of devices

Induction crucible furnaces

It is the most common type of induction heating furnace. A distinctive feature that differs from other types is that an alternating magnetic field appears in it in the absence of a standard core. Cylinder shaped crucible located inside the inductor cavity. The furnace, or crucible, is made of a material that perfectly resists fire and is connected to alternating electric current.

Positive aspects

Crucible units include to environmentally friendly heat sources, the environment is not polluted from metal smelting.

There are disadvantages in the operation of crucible furnaces:

during technological processing, slags at low temperatures are used;
The produced lining of crucible furnaces has low resistance to destruction, this is most noticeable during sudden temperature changes.

The existing disadvantages do not pose any particular difficulties; the advantages of a crucible induction unit for melting metal are obvious and have made this type of device popular and in demand among a wide range of consumers.

Channel induction melting furnaces

This type is widely used in the smelting of non-ferrous metals. Effectively used for copper and copper alloys based on brass, cupronickel, bronze. Aluminum, zinc and alloys containing these metals are actively melted in channel units. The widespread use of furnaces of this type is limited due to the inability to provide a fracture-resistant lining on the inner walls of the chamber.

Molten metal in channel induction furnaces undergoes thermal and electrodynamic movement, which ensures constant homogeneity of mixing of alloy components in the furnace bath. The use of channel furnaces of the induction principle is justified in cases where special requirements are imposed on the molten metal and manufactured ingots. The alloys are of high quality in terms of gas saturation coefficient and the presence of organic and synthetic impurities in the metal.

Channel induction furnaces operate like a mixer and are designed to level the composition, maintain a constant process temperature, and select the pouring speed into crystallizers or molds. For each alloy and casting composition, there are parameters for a special charge.

Advantages

the alloy is heated in the lower part, to which there is no air access, which reduces evaporation from the upper surface, heated to a minimum temperature;
channel furnaces are classified as economical induction furnaces, since the melting that occurs is ensured by a low consumption of electrical energy;
the furnace has a high efficiency due to the use of a closed loop magnetic wire;
Constant circulation of molten metal in the furnace accelerates the melting process and promotes uniform mixing of alloy components.

Flaws

the durability of the stone internal lining decreases when high temperatures are used;
the lining is destroyed when melting chemically aggressive alloys of bronze, tin and lead.
when melting contaminated low-grade charge, the channels become clogged;
the surface slag in the bath does not heat up to a high temperature, which does not allow operations to be carried out in the gap between the metal and the shelter and to melt chips and scrap;
channel units do not tolerate interruptions in operation, which forces them to constantly store a significant amount of liquid alloy in the furnace mouth.

Complete removal of molten metal from the furnace leads to its rapid cracking. For the same reason, it is impossible to perform a quick conversion from one alloy to another, you have to make several intermediate melts, called ballast.

Vacuum induction furnaces

This type is widely used for melting high quality steels and heat-resistant nickel, cobalt and iron alloys. The unit successfully copes with the melting of non-ferrous metals. Glass is boiled in vacuum units, parts are treated with high temperature, produce single crystals.

The furnace is classified as a high-frequency generator located in an inductor isolated from the external environment, passing a high-frequency current. To create a vacuum, air masses are pumped out of it. All operations for introducing additives, loading the charge, and dispensing metal are carried out by automatic mechanisms with electrical or hydraulic control. Alloys with small admixtures of oxygen, hydrogen, nitrogen, and organics are obtained from vacuum furnaces. The result is far superior to open induction ovens.

Heat-resistant steel from vacuum furnaces used in tool and weapons production. Some nickel alloys containing nickel and titanium are chemically active, and it is problematic to obtain them in other types of furnaces. Vacuum furnaces perform metal pouring by rotating the crucible in the internal space of the casing or by rotating the chamber with a fixed furnace. Some models have an opening hole in the bottom to drain metal into an installed container.

Crucible furnaces with transistor converter

Used for limited weight non-ferrous metals. They are mobile, light in weight and can be easily moved from place to place. The furnace package includes a high-voltage transistor universal converter. Allows you to select the power recommended for connecting to the network, and, accordingly, the type of converter that is needed in this case with changing the weight parameters of the alloy.

Transistor Induction Furnace Widely used for metallurgical processing. With its help, parts are heated in blacksmithing and metal objects are hardened. Crucibles in transistor furnaces are made of ceramics or graphite; the former are designed to melt ferromagnetic metals such as cast iron or steel. Graphite is installed to melt brass, copper, silver, bronze and gold. They melt glass and silicon. Aluminum melts well using cast iron or steel crucibles.

What is the lining of induction furnaces

Its purpose is to protect the furnace casing from the destructive effects of high temperatures. A side effect is the preservation of heat, therefore process efficiency increases.

The crucible in the design of an induction furnace is made in one of the following ways:

by the method of excavation in small-volume ovens;
by the printed method from refractory material in the form of masonry;
combined, combining ceramics and a buffer layer between the masonry and the indicator.

The lining is made of quartzite, corundum, graphite, fireclay graphite, magnesite. Additives are added to all these materials to improve the characteristics of the lining, reduce volume changes, improve sintering, and increase the resistance of the layer to aggressive materials.

To select a particular material for lining take into account a number of accompanying conditions, namely, the type of metal, the price and refractory properties of the crucible, the service life of the composition. A correctly selected lining composition should provide the technical requirements for the process:

obtaining high quality ingots;
the largest amount of full melting without repair work;
safe work of specialists;
stability and continuity of the smelting process;
obtaining high-quality material using an economical amount of resources;
use of common materials for lining at a low price;
minimal impact on the surrounding space.

The use of induction furnaces allows you to obtain alloys and metals of excellent quality with a minimum content of various impurities and oxygen, which increases their use in complex areas of production.

MELTING FURNACE is a foundry furnace with an inductor for melting metal. The advantage is that the melting mass is perfectly mixed to a homogeneous composition if an induction melting furnace is used. Induction technology speeds up the process of metal melting (melting time 45 minutes), such furnaces have good characteristics! ZAVODRR – melting furnaces for steel, aluminum, copper from professionals!

How do smelting furnaces work?

Melting furnaces are a working chamber into which the feedstock (charge), materials and materials that intensify the formation of the melt are placed. The chamber is separated from the outer casing by a fire-resistant lining, as well as a heat-insulating layer. Depending on the type of energy carrier used or the heating method (induction method, graphite electrodes, gas burners), the design of the chamber depends, as well as the time and quality of the output material. Let's look at the design of melting furnaces.

- IN arc melting furnaces a device for draining the melt and separating slag masses is located in the lower part of the furnace. Electrodes are placed on top; their number is from 1 to 4 pieces. A transformer acts as a power source. The disadvantage of this method may be sintering of the metal.

– Induction melting furnace consists of an inductor, inside of which there is a crucible with a refractory lining. The equipment is equipped with charge loading mechanisms, systems ensuring complete drainage of the finished melt, control and adjustment systems. In induction melting furnaces, the metal is poured from the top. Thyristor or transistor converters act as a power source. The quality of the melted metal in this way is the best, because the induction method is constant uniform mixing of the charge during melting; The design of melting furnaces depends on their type.

– Gas melting furnaces have the simplest and cheapest design. A gas burner is connected to the melting unit in the lower part, which runs on regular main gas (methane). Typically, these furnaces are used to smelt metals with low specific calorific value, such as aluminum or copper.

Melting furnaces - advantages

When choosing a melting furnace, you need to know its disadvantages and advantages. The main advantage of gas melting furnaces is the minimal cost of metal melting, because gas is the cheapest energy carrier. Induction melting furnaces allow you to obtain excellent melt quality at the output. Electric arc – to achieve the maximum melting temperature for refractory materials or alloys. All types of furnaces have good process automation and a small amount of harmful atmospheric emissions.

The advantages of using induction furnaces are obvious:

production technology makes it possible to obtain high-quality melts with a homogeneous chemical composition,
it is possible to introduce additional alloying elements,
furnaces have a high efficiency of about 95%,
relatively small waste,
production technology that is safe for personnel health,
production efficiency achieved by releasing a large amount of heat from the metal, which allows consuming less power.

The main characteristics of thermal installations are the capacity of the working chamber, which determines the productivity, the type of material for which it is intended for smelting and the rated power of the heating element, which sets the maximum operating temperature, as well as the energy intensity of the process.

Paying attention to the characteristics of the equipment when choosing induction furnaces, it is worth paying special attention to the quality of the crucible. On average, the crucible is designed for a number of melts from 20 to 60. The induction furnace set, in addition to the crucible, includes:

frequency converter (transistor or thyristor),
capacitor banks,
melting units,
water-cooled cables,
cooling systems and control panels.

Management and control of the smelting process must be carried out by specially trained personnel.

The heating element of such installations can operate at both industrial and medium frequencies. The advantages of this solution are complete control over oxidative processes, as well as complete drainage of the melt. Both acidic and basic materials can be used as linings.

Melting furnaces for melting metal are the most popular equipment for metallurgical enterprises. Induction melting furnaces make the smelting process more economical and of higher quality. Depending on the type of metal and the volume of the charge, the process of melting metal in an induction furnace takes on average from 30 minutes to 1.5 hours. Induction furnaces allow for heat treatment of ferrous, non-ferrous and even precious metals.

Steel melting occurs at a temperature of 1500-1600 degrees Celsius. During the smelting process, it is necessary to reduce the content of substances that degrade the quality of steel, such as sulfur, phosphorus and oxygen. The choice of lining depends on the composition of the desired melt. Induction furnaces are ideal for the production of alloy steels. On average, steel melting time takes about 1 hour.

These furnaces operate primarily at industrial frequencies of 50 Hz and are equipped with high-precision automation that allows you to control both the temperature and the intensity of segregation. The amount of waste in them barely reaches 2%, in addition, they are not demanding on the quality of preparation of charge materials.

The melting point of aluminum is 660 degrees Celsius, so it is important that the thyristor converter is not too powerful. A melting unit for melting aluminum should not be used for melting other metals. Using an induction furnace for melting aluminum and its alloys will produce a homogeneous, high-quality melt.

A distinctive feature of such furnaces is their low heating temperature and... as a result, low power consumption. Graphite is common as the main material for the crucible; in addition, to intensify the process, a metal core can be used, connected to a mid-frequency network through a step-down transformer. The maximum heating temperature, as a rule, does not exceed 750 ºС.

Copper Melting Furnaces

Melting copper in an induction furnace takes no more than 40 minutes. The process of obtaining the melt occurs at a temperature of 1000-1300 degrees Celsius. Melting can be done in a vacuum, in a protective gas environment or in an open environment. Due to its high thermal and electrical conductivity and flexibility, copper is widely used in various industries.

When producing copper melt, it is very important to ensure chemical purity, therefore, furnaces, in some cases, have a sealed working chamber, and induction heating is carried out in a soft mode. There are no significant design differences from induction furnaces for non-ferrous metals, but the main requirement is the absence of a direct reaction between the crucible material and the melt.

Melting furnaces - transistorized

Small foundries use transistor furnaces to melt the charge. These furnaces use a mid-frequency induction heater. Melting of metals is carried out in a graphite crucible. In transistor furnaces, dynamic circulation of the metal melt inside the crucible occurs, due to which the temperature is equalized throughout the entire volume of the crucible, which helps to obtain a homogeneous chemical composition of the multicomponent alloy. In such furnaces, a quick transition from one grade of alloy to another is possible.

Transistor induction furnaces are distinguished by their versatility and extremely high efficiency, which can reach 99%; instead of the usual copper winding, they use an induction heater assembled on a system of interconnected transistors. Another advantage is the electrodynamic circulation, which ensures uniform mixing of the melt.

Another type of induction furnace is installation. In which, to stabilize the heating process and ensure the possibility of its regulation, thyristor frequency converters of current are used, ensuring the formation of an electromagnetic field.