A furnace in which one complete group of material is placed in the furnace, heated (and may have some other treatment) and removed before the next group is positioned in place.

A type of mobile batch furnace that is cylindrically shaped and moved from load to load with a crane. The material is placed on a fixed hearth or “base” and then covered with a retort or “inner cover” to provide a gas-tight chamber for the furnace atmosphere. The bell furnace is then placed onto the base over the inner cover. Bell furnace systems use a convection fan that is located in the base below the material. A “forced cooler” may be placed over the inner cover to reduce the temperature to a level that will not discolor the material when exposed to air.

A furnace in which material is continuously fed. For the wire industry, the material can be fed without unwinding the coil (e.g. as in a pusher-type furnace). Or, the material can be fed by unwinding one or more coils and pulling the individual strands through.

One of two major types of facilities used to produce liquid steel (the other being a Basic Oxygen Furnace). The furnace uses electrical resistance or induction to form molten steel. The product is tapped into a ladle, subsequently strand cast directly into blooms or billets, or teemed into ingots for further working.

A furnace in which convection is the most significant means of heat transfer. Also known as “convection furnaces,” such furnaces typically have some sort of fan to circulate the cold gas across the heat source and into the chamber containing the material to be heated.

A furnace whose heat is obtained from electrical current flow in the material to be heated. Alternating current in induction coils that surround, but do not touch the material, cause a second­ary current to flow in that material. The secondary electrical current generates heat in the material based on the electrical resistance characteristics of the material.

A furnace for melting metal in which the bath is heated by the convection of hot gases over the surface of the metal and by radiation from the roof. Until the second half of the 20th century, most of the world steel was produced in the open-hearth furnace. By the middle of the 20th century, the open-hearth process was surpassed by other technologies. The last open-hearth furnaces in North America were bricked up in the 1980s.

A furnace in which the material is either indexed or continuously moved through-force applied at the entry-end. Typically, the material is loaded onto some form of conveyance (e.g., trays with rollers), and then is pushed through the furnace to exit at the opposite end.

A gas furnace in which the products of combustion do not enter the furnace, but are circulated through tubular elements from which the heat is transmitted to the charge by radiation. Also called a gas tube furnace.

A furnace in which the charge is moved over driven rollers, sometimes water-cooled.

A furnace that is annular in plan, moving round continuously or intermittently, conveying its charge from the charging to the discharging doors.

A furnace in which the material to be heated is placed in or passed through molten salt. The molten salt acts both as a temperature transfer medium, as well as a protective barrier against damage to the material being heated, which could occur if it is heated in ambient air.

A furnace open at both ends in which product is passed through. Also called a pit furnace.

A furnace for small parts that are placed on a grooved or plain plate which is agitated at predetermined intervals, causing the charge to move through the heating zone at a controlled speed.

A continuous furnace in which wires are run straight from bobbins through the heating and cooling chambers, the tension being maintained by the winding frames situated adjacent to the exit end of the cooling chamber. For annealing, it is necessary for each wire to run through a small-bore tube into which the protective atmosphere is introduced.

A furnace that has tubes through which individual wires can run through continuously.

A protecting device that opens a circuit when the fusible element is severed by heating, due to over-current passing through. Rating: voltage, normal current, maximum let-thru current, time delay of interruption.

A fuse that has both an over-current limit and a time delay before activation.

A fuse that must be replaced after it interrupts a circuit. Also referred to as a one-time fuse.

A fuse that may be reused after current interruption by replacing the meltable link.