An induction furnace is an electrical furnace in which the heat is applied by induction heating of a conductive medium (usually a metal) in a crucible around which water-cooled magnetic coils are wound. The advantage of the induction furnace is a clean, energy-efficient and well-controllable melting process compared to most other means of metal melting. Most modern foundries use this type of furnace and now also more iron foundries are replacing cupolas with induction furnaces to melt cast iron, as the former emit lots of dust and other pollutants. Induction furnace capacities range from less than one kilogram to one hundred tonnes capacity, and are used to melt iron and steel, copper, aluminium, and precious metals. The one major drawback to induction furnace usage in a foundry is the lack of refining capacity; charge materials must be clean of oxidation products and of a known composition, and some alloying elements may be lost due to oxidation (and must be re-added to the melt). Image File history File links No higher resolution available. ... Image File history File links Induction-furnace-pic. ... A furnace is a device for heating air or any other fluid. ... A semiconductor induction heater with a small inductor Induction heating is the process of heating a metal object by electromagnetic induction, where eddy currents are generated within the metal and resistance leads to Joule heating of the metal. ... Hot metal work from a blacksmith In chemistry, a metal (Greek: Metallon) is an element that readily loses electrons to form positive ions (cations) and has metallic bonds between metal atoms. ... Crucibles used in Czochralski method A crucible is a cup-shaped piece of laboratory equipment used to contain chemical compounds when heating them to very high temperatures. ... A coil is a series of loops. ... The term foundry originally was a synonym for an ironworks or general metal works where metal casting operations were performed. ... Blast furnace in Sestao, Spain. ... Cast iron usually refers to grey cast iron, but can mean any of a group of iron-based alloys containing more than 2% carbon (alloys with less carbon are carbon steel by definition). ... After just three years of use, dust has blocked this laptop heat sink, making the computer unusable Dust is a general name for minute solid particles with diameters less than 500 micrometers (otherwise, please see sand or granulates and, more generally, finely divided matter). ... Many of the compounds which are dangerous to the environment can also be harmful to humans in the long-term range and come from mineral and fossil sources or are produced by humans themselves. ... General Name, Symbol, Number iron, Fe, 26 Chemical series transition metals Group, Period, Block 8, 4, d Appearance lustrous metallic with a grayish tinge Standard atomic weight 55. ... The steel cable of a colliery winding tower. ... General Name, Symbol, Number copper, Cu, 29 Chemical series transition metals Group, Period, Block 11, 4, d Appearance metallic pinkish red Standard atomic weight 63. ... General Name, Symbol, Number aluminium, Al, 13 Chemical series poor metals Group, Period, Block 13, 3, p Appearance silvery Standard atomic weight 26. ... A precious metal is a rare metallic element of high, durable economic value. ...

Operating frequencies range from mains frequency (50 or 60 Hz) to 10 kHz, usually depending on the material being melted, the capacity of the furnace and the melting speed required - a higher frequency furnace is usually faster to melt a charge. Lower frequencies generate more turbulence in the metal, reducing the power that can be applied to the melt. The utility frequency (American English) or mains frequency (British English) is the frequency at which alternating current (AC) is transmitted from a power plant to the end user. ... The hertz (symbol: Hz) is the SI unit of frequency. ...

A preheated 1-tonne furnace melting iron can melt cold charge to tapping readiness within an hour.

An operating induction furnace usually emits a hum or whine (due to magnetostriction), the pitch of which can be used by operators to identify whether the furnace is operating correctly, or at what power level. Magnetostriction is a property of ferromagnetic materials that causes them to change their shape when subjected to a magnetic field. ...

See also

• Electric arc furnace - for another type of electric furnace, used in larger foundries and mini-mill steelmaking operations

An electric arc furnace is a system that heats the charged material by means of an electric arc. ...

References

• Foseco Ferrous Foundryman's Handbook, Elsevier, 2000