So, it’s worth starting with the fact that only those people who are engaged in roasting, hardening or smelting any materials need to assemble a muffle furnace with their own hands. This equipment is not intended for space heating. It is also worth noting that a homemade model will, of course, take a long time, several days to dry, but it will be much cheaper than buying a ready-made fixture, since its price is very high.
Oven description
It is possible to smelt in a furnace not only metal, but also ceramics, glass, wax. A wide variety of work that can be performed with this equipment is due to the fact that the operating temperature range inside the furnace is from +20 to +1000 degrees Celsius. The process of assembling a muffle furnace with your own hands can be carried out quickly enough, provided that all the necessary components are at hand. However, you will have to give a few days for the material to dry, as it is often made from fireclay bricks.
Use the unit
Naturally, for a home-made device to be made, it is necessary to clearly understand the principle of operation of the device, otherwise the work will initially be doomed to failure. It’s worth starting with the fact that four sources can be used as fuel for the operation of the furnace: electricity, gas, coal, firewood. Since the muffle furnace will be made by hand, it is recommended to take on the implementation of the electric version of the power source. It consists of two main components: a heating chamber and thermal insulation that retains heat inside. A refractory brick should be used as a heat accumulator. Heat treatment takes place inside the working chamber - the muffle. Hence the name of the unit. To assemble a muffle furnace with your own hands, it is best to use a porcelain mold, for example, from ceramic plates.
Naturally, you need to take into account the fact that the melting temperature of the selected material for the mold must be higher than the melting temperature of the material being processed. Most often, a homemade muffle furnace made from such materials is used to melt a small amount of metal at a time, as well as to harden tools.
Types of ovens
Before proceeding to the assembly, you need to decide what kind of equipment you need to assemble. From a structural point of view, there are tubular or cylindrical, horizontal or vertical types.
They also differ in the type of heat treatment composition. A do-it-yourself muffle furnace for melting metal can be air, vacuum type or use an inert gas. However, it is worth noting that only one option can be implemented at home - air. Therefore, this option will be described. Furnaces can also be divided into two classes according to the features of their thermoelectric heater. It can be gas or electric type. Of course, it is more profitable to use the gas option in terms of fuel costs, however, firstly, it is very difficult to create it technically, and secondly, it is prohibited by law to make muffle furnaces for melting with a gas heater.
Begin assembly
It will be about creating a unit for firing ceramics at home. For this, a vertical type of furnace will be assembled. As the main tools you will need: a grinder and two circles, arc welding and electrodes, a metalwork tool, nichrome wire 2 mm thick. As materials you need to have on hand: a used oven body or a steel sheet 2.5 mm thick, corners, fittings, bas alt wool, refractory mortar and fireclay bricks, silicone sealant.
Production of basic elements
Assembling a metal muffle furnace with your own hands includes the production of three main elements: a body, a heating element, and a thermal insulation layer.
The ideal option is to use the case from an old electric oven. Here already providedall means of protection and thermal insulation. It will only be necessary to remove all unnecessary plastic parts. If this is not possible, then the body is welded from a metal sheet, which is first cut into blanks of the desired size. After welding, be sure to clean the seams with a grinder or a metal brush and coat them with a primer.
Further, to make a do-it-yourself muffle furnace for vertical-type ceramics, you will need a heating element - this is a key part of the entire furnace. The heating rate and maximum temperature will depend on it. It is worth adding here that for such furnaces a necessary element is a thermostat, which you can assemble with your own hands or buy. Nichrome wire will be used as the heating part in this example. It is important to know here that its diameter depends on the maximum heating temperature. The higher the temperature, the thicker the element should be. Today, the minimum and most popular diameter is 1.5-2 mm.
It can also be noted that nichrome can withstand heating temperatures up to 1100 degrees, but burns out if air enters the heated element. If it is not possible to cover the wire, then it is better to use fechral. The maximum temperature for this substance is 1300 degrees, and there will be no problems with air entering.
Another important part is thermal insulation, which is responsible for the efficiency of the structure. The installation of this layer is carried out inside the muffle furnace. For this, fire-resistant glue and fireclay bricks are used.
How to make a muffle furnace with your own hands?
The case is made as follows. A rectangle of the required dimensions is cut out of sheet metal. After that, it is bent into a cylinder, and the seam is welded. The next step is to cut a circle out of the same metal and weld it to one side of the cylinder. Thus, it will look like a barrel. The bottom will need to be reinforced with corners and reinforcement. You can also use a rectangular shape of the oven, rather than a cylindrical one, it does not matter.
Insulation Arrangement
Bas alt wool is laid out around the entire perimeter of the rectangle or cylinder. This material should be used for the following reasons:
- Off. The material can withstand temperatures up to 1114 degrees. Upon reaching this threshold, the cotton wool will melt, it will not start burning.
- Eco-friendly. This resource has no harmful impurities, as it is made from natural materials. Therefore, when heated, there will also be no harmful fumes.
Special buttons are used to fix cotton wool on the body of the oven.
The second step in arranging insulation is laying fireclay bricks. Only this material can be used, since 75% of the composition is refractory clay. This ensures normal operation, and even at high temperatures, the raw material will not burst.
Finishing work
The working chamber for the oven is made of brick or ceramic. AfterTo do this, it is placed in a steel case prepared in advance, which already has thermal insulation. It is very important to note here that there must be a distance of at least 4 cm between the walls of the chamber and the walls of the housing. A heater is placed in this gap. The cover for the muffle furnace should be made of two layers of metal, between which there is a layer of thermal insulation. Naturally, we must not forget about the arrangement of the handle for opening the oven.
After that, several holes must be made in the case through which the wires of the heating element and the thermal sensor can be brought out. The connection is made to a separate cable, which, to increase security, will be attached to the 20A machine. A ceramic cartridge can be used as a connection between the output and the cable. Steel pipes are used as legs for the body. They can be welded or screwed on. If a bolted connection is used, the bottom of the chamber must be raised so that the bolts are on the outside.
