The metal melting furnace has been around for thousands of years. Today, the induction melting furnace is used in the modern world for the production of steel and other materials, and the induction forge and inductotherm metal melting furnace technology are largely taken for granted. But while the technology is somewhat new, the process is very old and in some ways things haven’t changed: we’re just as dependent on the metal melting furnace for industry today as we ever were in ancient times.
The Reason For Metallurgy
Metallurgy is the process of making metals into something else, such as a tool. Most metals are not found in their pure form and must be heated in order to remove the impurities, or things other than metal, from the ore in which they naturally exist. Our very ancient ancestors got their metal by pounding on the ore to chip off pieces, but it wasn’t long before we developed a metal melting furnace to get at this valuable material.
The first worked metals were softer metals like copper, gold, silver, lead, tin, and bronze. We have evidence of copper working as early as 6000 BC, though this was mostly for use in beads. Bronze was more valued because it is a harder metal and was useful for making tools and other useful products.
The Iron Age
The metal melting furnace really came into its own in working with iron. This did not happen until about 1200 BC because iron needs extremely hot temperatures in order to be worked properly. Before that time, kilns and forges were simply incapable of reaching the necessary melting point of iron: 1535°C. Cast-iron proved to be not only cheap, but also extremely useful in making tools, cookware, weapons, and armor.
A kind of steel made by removing carbon from iron was in use in China as early as 206 BC. However, true
reliable steel could not be made until some time later, mainly because of limitations on the ancient metal melting furnace
Important Ancient Metal Finds
Our understanding of the evolution of the forging and metallurgy process is based in part upon historical records and stories and in part upon archaeological finds. Some of the most important archaeological finds include Otzi, a naturally mummified corpse who died with a copper casted ax head on his person. Otzi died in 3300 BC. From 3000 BC we have examples of weapons and copper cult objects from the Middle East and India. In 800 BC we have the first record of cast-iron being produced by the Chinese. The first cast crucible steel object we have found comes from 500 AD. India.
Most information about forges and furnaces in antiquity is incidental and passing rather than a direct historical record. Possibly the most famous metal melting furnace from ancient history is the furnace by King Nebuchadnezzar of Babylon, recorded in the book of Daniel in the Bible. According to the story, Nebuchadnezzar used metal furnaces to work a metal image of himself, and when three captives refused to worship the image rather than their own God, Nebuchadnezzar ordered the furnaces heated to their maximum temperature and the rebellious captives thrown in. According to the story, the three came out of the furnace untouched, to the complete shock of the king and all bystanders.
The Modern Metal Melting Furnace
The most dramatic development in modern metal techniques is the use of induction heating to melt metal. Induction hardening and induction melting are far more energy-efficient ways of dealing with metals because they work by the application of an electrical current that creates a magnetic field and agitates the material to produce heat. Thus the material inside heats evenly and without coming into direct contact with the heat source, unlike the type of metal melting furnaces we have used since 6000 BC. The induction melting furnace also does not require a warm-up or cool-down and does not have to be kept in a standby mode between jobs.
Our ancient ancestors could never have imagined induction in the amazing metalworking processes we have access to today. What they would understand, though, is that metal production and casting is just as important today as it was thousands of years ago.