Materials and supplies for the job
Muffle furnace for melting aluminum with their own hands or hardening steel parts. for the production of preparing a complete set of materials. We will need:
- fireclay brick;
- thermal insulation;
- Sheet metal or any improvised material. If there is an old safe with an inner layer of sand, then you are lucky. Such a stove will last a long time and will save on the outer layer of insulation;
- Refractory clay, sand or ready-mixed masonry bricks. For caulking cracks and voids, a fireproof sealant can be purchased or a mortar can be used;
- Electric cable, ceramic insulators, automatic circuit breaker for connection in the switchboard.
How to make a muffle furnace with your own hands?
Muffle furnace is primarily used for heat treatment of various things. It produces melting, hardening and firing of metal, glass, wax and even ceramic materials. Thanks to the versatility of such a unit, a sufficiently wide temperature range of up to 1000º C is provided.
If you need to have such a device in your arsenal, you can easily make it yourself, because the of muffle furnace devices are rather high in stores. Self-assembly of such a unit is fast enough, especially if the necessary materials and tools are prepared.
What is a muffle furnace?
Muffle furnace. a thermal device designed to heat materials to a predetermined temperature. It consists of a heating chamber and a capsule (muffle) in which the object to be treated is placed.
The scope of application of the devices is quite extensive:
- Laboratory analysis. Many minerals show their properties at high temperature.
- Forging. Workpieces can be heated while keeping their shape and free from scale.
- Hardening of the metal. The heat treatment changes the crystal structure, increasing strength and hardness.
- Melting. Separation of the desired substance from the heterogeneous material. This is how ingots of aluminum, gold, and silver are produced.
- Annealing. Helps to achieve the required microstructure in the production of parts from several components.
- Annealing. Imparting the required properties to the objects, such as hardness, presentability, resistance to moisture and chemical reagents.
- Heat Treatment. Removal of water, acid, oils, and other liquids from the substance in order to dry it completely.
- Tempering. Releasing internal tensions after melting or hardening, achieving ductility.
- Ashing. Remove the foreign particles by burning them. Determining the presence of minerals in the alloy under study.
Using the functions of the device allows for beautiful ceramics, souvenirs, unique metal items.
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It all started when I needed a furnace for. stuff. I wanted to melt and steel, and burn my hands, the whole set, in short. I decided to take the easy way and ordered this one from ali for 10k (5k shipping):
Worked exactly two melts _ after which the coil leaked and spoiled the muffle:
I strongly advise against buying the furnace from Chinese. However, I was able to get a full refund, ali sided with me. But excluding shipping. I lost 5 grand, but I still have what is left of the furnace. a graphite crucible, a bunch of refractories, thermocouple and regulator, and fancy tongs. In the end almost a draw, I guess.
The furnace is dead, long live a new furnace!I have already made this one myself with these:Fireclay bricks SHL. 1 (I think, I don’t remember exactly what number):
We need a lightweight fireclay, as it is very convenient to cut grooves for the coil, and it is also very light (brittle, on the other hand). Cut grooves in four bricks so that there is a spiral, rising from the bottom up to lay in this spiral, another spiral of fehral. I made the bottom out of a couple of these bricks, and cut a couple more into plugs in the corners of the stove. You can glue everything in place with refractory masonry compound for fireplaces and stoves, refractory sealant, or refractory glue, too.
Then, be sure to need fechral, or even better superechral. Nichrome is not suitable, it burns out in contact with the air. I bought in Novosibirsk such a roll (what’s on top do not pay attention):
Sell it by weight and there are 3 kg, this wire has a resistivity of 1.78 µOhm per meter. The calculation of the required length of wire is very simple: the square of the voltage divided by the power (I needed 1.5 kW) and for resistivity. That is, in my case: 220220/1500 = 32 ohms. 32/1.78=18 meters. All in all, we take 18 meters of wire and wind it on some rod with necessary diameter. so it fits well into the grooves cut into the bricks. Fast winding can be done, for example, with an electric screwdriver. I coiled by hand %-)The spiral will need to stretch so that the coils are not touching each other and put into the grooves
The tighter you can fit the spiral into the grooves and corners, the better. The feathering gets softer when heated and can sag and fall out of the grooves. Outside of the coil comes out the top and bottom (in the top photo shows the output from above). It is worth to twist the outputs in half, so that the wire does not heat up too much. I connected the ends with copper wires to the electronic remains of the Chinese stove. I won’t disassemble my oven to photograph them, but such regulators are sold in large radio parts stores. They look like this (on the left):
In principle you can switch it on already and everything will work (for melting aluminum it should be enough). However, with more or less prolonged use there will be high heat losses and it will not be possible to develop the temperature for melting copper, for example. In this case mullite-silica wool, the same felt or some ceramic wool can help. All this stuff is sold in online stores of refractories and is quite affordable by the kilo. You should wrap it around the working chamber and in general fill up all the holes with it, so that the heat does not go out of the chamber. The lid should be made of lightweight chamotte and a lot of absorbent cotton, so that it fits better %-) In short it is better to make the chamber as more isolated as possible from outside world.
I, however, still do not get to the lid, so I just put the ceramic fiber from the Chinese oven in three layers on top (at 1000 degrees inside you can easily press the fiber on top of the unprotected hand).Oh yes, I forgot something. Mullite-silica wool impregnated with some oily nonsense to make it easier to place. When heated, it burns out and smells quite noticeable, at first the absorbent cotton will smoke, then normal.
One more thing. The thermocouple (aka thermometer) should definitely not be placed on top, like mine. The thing is that in this position it lies about the temperature, shows, in my case, about 100 degrees lower than in the work area, where the workpiece is hanging in the photo above.
And, of course, keep in mind that there is a current in the spiral. Before you get into the furnace, you should turn off the power or be extremely careful not to hit the coil under voltage.
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Classification of muffle furnaces
Muffle furnaces are subdivided according to the type of heating elements:
There are also industrial and homemade muffle furnaces.
Industrial muffle furnace with automation
But it is impossible to make gas-fired furnaces at home, although gas is cheaper than electricity, as such experiments are forbidden by law. Electric control of the furnace provides the convenience of temperature control.
According to the design type, muffle furnaces are divided into:
Heating can take place in an air environment, in a vacuum or in a gas environment. At home there is an opportunity only to design an oven with heat treatment of products in an air environment.
If you make your own muffle stove, you can give it the desired shape and volume, to decorate it in a suitable style for the interior.
The main parts of the design
- The outside part of the furnace, the shell (housing).As the body for the future muffle furnace is convenient to use a used gas stove, or rather an oven from it, or an electric stove. To use them, remove all plastic parts. When it is not possible to use such variants of the case, it is welded from sheet metal (thickness of at least two millimeters).
- Insulating layer. This part of the design is extremely important. On its quality depends on the efficiency of the furnace and the heat loss it will incur. The inner layer of thermal insulation is a refractory (fireclay) brick, capable of withstanding temperatures up to one thousand degrees.
Refractory fireclay bricks for the interior decoration of the muffle furnace
Spirals twisted from nichrome or fehral wire
The list of materials and tools for assembling the construction
- angle grinder (a machine for grinding and cutting materials) with cutting discs for metal;
- 2mm thick sheet steel;
- metal corners;
- fireclay fireproof brick;
- refractory mix;
- heat-resistant silicone;
- basalt thermal insulator (wool, density 200 kg/m3) or perlite;
- safety glasses and a respirator;
- Nichrome (Fechral) wire of 1 mm cross-section;
- wire cutters or metal scissors.
Muffle kiln for melting aluminum with your own hands
What is a muffle furnace and what is it for. Muffle furnace is an indispensable device for heating various metals at home.
Such a furnace allows you to successfully melt metals such as aluminum, copper, many non-ferrous metals, as well as drying, firing ceramic products, as well as cremation.
Muffle Furnace Types. Muffle furnaces are available in different forms, they can be electric, gas, air, vacuum, and by their design: bell-shaped, horizontal, vertical and tubular.
Feature of the muffle furnace. The muffle furnace is unique in that it contains a working area called a muffle, which helps protect the metal being processed.
The process of making a muffle furnace
As a heating tool, you can opt for an electric heater, because such a heater is very easy to control.
Basic elements of a muffle furnace. The muffle furnace has components such as a heating chamber and a special heat accumulator.
It is necessary to provide heat regulation in order to ensure uninterrupted operation during aluminum processing.
If more than one material is to be melted, then it makes sense to melt aluminum more than once. Therefore, the heat accumulator will function as a heat regulator, so that the furnace does not have time to cool down in the process.
It is important not to overdo with the choice of the accumulator, so that the furnace does not become too inertial.
To make a muffle furnace, we will need the following:
- 7 bricks;
- Angle grinder;
- a metal bucket;
- an unnecessary piece of metal;
- safety goggles;
- a hammer, etc.п.
Prepare 7 plain bricks, you will need them as a temperature accumulator.
Take an angle grinder and build a compartment on each side of the brick. This will create a working space for the electric heater.
For the strength of the construction, take a wire and wrap it around the bricks.
You can use a wide metal bucket for the refractory chamber. It can also be made with your own hands.
To create the body of the future muffle furnace will need a piece of unnecessary metal sheet, 1 mm 1.5 mm thick and a layer of rust.
When designing the height of the bucket do it with a certain reserve, because the working chamber will have to install on a layer of bricks with insulation.
The process of screwing the sheet into the pipe is quite problematic, so we advise you to use special rings made of thin rebar.
Next, you need to bend the armature and connect its ends to get a circular shape take a hammer.
Take the rings and install them on the twisted sheet. Then connect them along the length of the circle.
The bottom of the furnace body can be made from a sheet that is already available. It is necessary to weld it to the bottom ring.
To set the surface of the working area of the furnace it is necessary to make a special hole in the brick for the electric heater. This action is necessary for the strength of the attachment structure.
Number the bricks and place them in order of priority, pressed tightly together. Check the stability of the structure.
To the bricks we attach the heating coil of the stove.
Delam marking grooves and install bricks, the result is a spiral arrangement of the heater.
Let’s saw through the grooves with the angle grinder. Don’t forget about personal safety! It is advisable to wear safety glasses.
For the coil, as a rule, nichrome or fechral is used.
Fechral is the best option, but in our case we will use nichrome. Heating of nichrome depends on the strength of the current, and the current depends on the voltage.
Carefully wind the spiral so that the turns are a little distance from each other. It is necessary to avoid short circuits.
Make a mortar and pour it carefully as shown on
They can be switched on at the same time and in sequence.
For example, the bottom heater is advisable to include when processing the material in small quantities at home, and two heaters will significantly increase the scale of melting.
Electric furnaces for melting metal
The basis of such a furnace is asbestos, which can be replaced by tile. Electrodes installed in the melting furnace with your own hands should have a voltage of 25 V.
They are made in the following order:
- Are made from the brushes of an electric motor.
- The assembly is drilled 6 mm holes.
- A wire with a cross section of 5 mm is hammered into it.
- A nail is hammered in to secure the wires.
- In order to improve the contact with the graphite, notches are made with a file.
Mica is placed inside the furnace as a heat insulator. When connecting to a network, a step-down transformer should be used. After making, the furnace is turned on and works for a while in idle mode.
Homemade Melting and Tempering Furnace for Metal at Home
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 large quantities of metal are installed in production. A furnace can be assembled at home to melt up to five kilograms of aluminum. Consider how to make a melting pot at home.
Melting metal at home
A device for melting aluminum and copper
Fusible metals are brittle. It is important to follow the schemes of work with this type of metals.
So, for example, to melt copper or aluminum, the muffle furnace must heat up to 1083, and to melt bronze 930 Celsius.
Muffle furnace for melting aluminum and brass
These materials have the highest melting temperatures of all the other fusible materials.
So, it begs the conclusion: to work with fusible metals, you need a furnace that heats to a maximum of 1100 degrees.
Nuance! For large castings, a hearth is used when working with low-melting metals. And you can melt the metal in a bowl with a spout (crucible). This is the easiest way to shape it afterwards.
Steps for working with fusible materials
- Heating up the furnace for casting at 600 degrees.
- Dipping mold.
- Heating the temperature to 900 degrees.
- We time the mold in the oven for 120 minutes.
- We take out the mold and cool it to 500 degrees.
- Easy-to-melt material fits into molds.