People often confuse melting furnaces and thermal processing equipment. As much as the two are often used in industries and seem to do similar jobs, they are different. For instance, thermal processing equipment is designed to increase the material’s temperature to the extent of changing its internal characteristics or surface.
When it comes to metals, they are known for their strength and hardness. However, thermal processing equipment has what it takes to increase its ductility regardless. It is important to note that the melting points of these materials are never exceeded during this process.
On the other hand, a melting furnace will heat metals beyond their boiling points. Consequently, their physical structures decompose, leading to liquefication. Whereas temperature plays a huge role during the process, pressure cannot be taken for granted.
Once the metal melts, the melting furnace generates and maintains the temperature needed to keep the mixture molten and homogenous for as long as necessary. We will be focusing on melting furnaces. So, let’s learn more about a melting furnace without further ado.
Types of Melting Furnaces
There are four major types of melting furnaces. Let’s take a look at them in detail.
⦁ Cupola Melting Furnace
This furnace is common among ferrous foundries and has a striking resemblance to blast furnaces. One major characteristic of the cupola furnaces is the chimney. It is high, cylindrical, and sturdy enough to withstand oxidation, abrasion, and too much heat. After all, its interior is well protected by a lining of blocks, bricks, and clay.
All that’s needed is placing the metal in the melting furnace. However, don’t forget to add limestone, ferroalloys, and coke before that. Their role is to initiate a chemical reaction to see any impurity inside the melting furnace float on the metal’s surface. However, it is important to note that very few foundries use cupola furnaces because they are not as energy-efficient as their counterparts.
⦁ Induction Melting Furnace
This melting furnace is suitable for ferrous alloys as well as non-ferrous ones. Its popularity is snowballing, and one of the reasons is its energy efficiency characteristic. These induction melting furnaces use AC (Alternating Electric) current to melt the metal at your preferred temperature.
For instance, if you are melting steel, the ideal temperature is 1370 degrees Celsius, equivalent to around 2500 degrees Fahrenheit. Place the metal alloy and addictive in a crucible. After that, surround that crucible with an induction heating coil. Expect it to heat the metal when charged.
It is also a popular melting furnace due to its simplicity as far as operating it is concerned. Additionally, what you get in the end once melting is over is also high-quality. However, that may not be the case if the raw materials contain impurities. After all, its refining capacity leaves a lot to be desired.
⦁ Crucible Furnaces
The materials of these melting furnaces are refractory materials, including ceramics. Their manufacturers ensure that they are hardy enough to withstand quite high temperatures, given the nature of the task they are supposed to perform. Since too much heat isn’t an issue, one will place the crucible above a source of heat.
Consequently, the metal and other addictive will melt over time. As far as the design is concerned, expect to come across different designs. The same case applies to the heating systems that various crucible melting furnaces use. Don’t expect the case to be any different regarding their sizes. Some of the different options include movable, fixed crucible furnaces and tiltable, fixed crucible furnaces.
People often choose this melting furnace because they come at a fair price. On top of that, their maintenance is easy, whereas the operation is simple. As a matter of fact, they are quite economical when melting small amounts of metal.
Nevertheless, you may want to find another alternative if you want to melt large quantities of metal. That’s because its operation is relatively manual, thus time-consuming. On the other hand, it would mean consuming a lot of energy, which is uneconomical.
⦁ Electric Arc Furnaces
Most people prefer using them to re-melt steel scrap, especially steel recycling. When the heating metal is in an electric arc furnace, the electrodes dipped in that metal play a significant role throughout the process.
They will generate the heat needed to melt your metal. As the name suggests, an electric arc is also involved during heat generation. It creates a gaseous electrical breakdown leading to plasma discharge responsible for its relatively rapid melting.
Depending on its design and size, an electric arc furnace can be in a position to heat 400 tonnes of metal at a go. Unfortunately, it is often associated with straining electrical grids. After all, such melting furnaces consume a lot of power.
That said and done, it does a good job, especially during scrap metal recycling hence worth the trouble. Equally important, a smelter is in a position to commence or halt the melting process whenever a need arises.
Conclusion
What is a melting furnace? Without any fear of contradiction, one can say that the above discussion has answered that question. Besides describing a furnace, it has also highlighted the various types of melting furnaces.
They include crucible, induction, electric arc, and cupola furnaces. They have their advantages and disadvantages, which should help you choose wisely. Weigh the two before choosing the one that suits your needs best.