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Induction Dictionary Created On : 05/16/2007 Category : General Interest List of terms commonly used in the induction heating industry. If you have an item you would like added, email me your information.	Article Submitted By: Sherlock Holmes Sherlock Holmes   (USA)
Anneal To soften by heating.   Axial Parallel to the axis or centerline   Billet A pre-cut length of material to be heated. Usually associated with a forging heater.  e.g. The billets in the billet heater were 7-1/2" long.     Brazing To solder (join) with a hard solder that has a high melting point. Usually associated with metals such as copper, brass, zinc.     Bussbar Any of a variety of solid and rigid electrical conductors. A bussbar may or may not be water cooled. Also referred to as a Buss.     Cable Any of a variety of non-rigid electrical conductors, often consisting of many strands of wire. A cable may or may not be water cooled.     Capacitor A device for storing charge of electricity. A capacitor is mainly used for determining the frequency of an induction heater. Units for a capacitor may be given in KVAR or micro-farads.     Channel Coil A type of induction coil that does not completely encompass the object to be heated, allowing the object to pass laterally through the coil.     Charge The material to be melted in the crucible of a melting furnace.   Chassis Ground Specifically meaning a connection to the machine chassis itself, however is more often used as a synonym for "common" and "earth ground". An electrical connection to the earth.     Coreless Furnace An induction coil assembly, including a high temperature refractory to protect the coil winding, and usually containing shunts. This term is usually associated with melting operations.     Crucible A container within which metals are heated. The crucible itself is non-conductive and therefore does not heat directly by the induction. Crucibles are often made of ceramic or refractory.     Curie Temperature. The point at which a magnetic object loses its magnetic capabilities. Typical of carbon steel, the Curie point occurs near 1300 degrees F. Magnetic permeability then equals unity.     Eddy Current Generally used to mean ANY current induced into an object by an adjacent magnetic field.  Specifically meaning "local eddies" of current.     Emissivity The coefficient of Emissivity is a unit used to describe the absorption or reflection of infra-red energy. The maximum value being unity (1). Each metal or alloy has a unique emissivity and the emissivity can (and does) change with temperature. When measuring temperature using Infra-Red Detectors, it is common to have to correct for emissivity of the object being measured.     End Effects Usually describing the divergence of magnetic field lines, (equipotentials), at the open ends of an induction coil. The diverging lines are a complex function of the coil geometry and the geometry of the heated object. The usage of "end effect" is normally an attempt at explaining how a part heats if the part is near the "end" of the coil.     Flux Concentrator A material that possess a magnetic permeability greater than unity and is used to focus or deflect magnetic fields. Typically ferrites, emulsified iron powders, or steel laminations.     Frequency Number of cycles per second. Expressed in units of Hertz (Hz) or kilo-Hertz (kHz). Historically called cycles per second (cps).     Fringe Effect  (Fringing)   The divergence (spreading out) of the magnetic field at the ends of a coil, resulting in less induction heating near the ends of a coil.   Furnace An induction coil assembly usually including high temperature refractory protecting the coil winding. This term is usually associated with melting operations.     Ground Specifically meaning the Earth itself, however is more often used as a synonym for "common", "chassis", and "earth ground". An electrical connection to the earth.     Hair Pin Coil A coil normally of less than one turn in the proximity of the heated object. (Single turn coils sometimes referred to as hairpin)     Harmonics A power supply may create multiples, (harmonics), of the intended fundamental output frequency. Also, a power supply may induce multiples, (harmonics), of the electrical utility BACK onto the electrical utility. Harmonics on the output of the power supply may or may not be desired. Harmonics induced back onto the electrical utility are definitely undesirable.     Inverter That portion of a power supply that creates the high frequency. Does not include the rectifier section nor the tuning, (load), section. However, in common usage a power supply is sometimes called an inverter.     KVA Volts times Amps times 1000.  A unit of measurement of Imaginary Power.   KVAR An acronym for "kilo volt amperes reactive". Essentially this is the volts across the capacitor times the current (amps) through the capacitor (at a given frequency).     Laminations Thin sheets of steel that also have an oxide coating. The coating acts as an electrical insulator. Normally hundreds (or thousands) of laminations are stacked together to form a flux concentrator or transformer core.     Line Frequency The frequency of electrical power supplied by the electrical utility. 60 Hz in the USA, and commonly 50 Hz in the UK.     Litz Wire A multi-stranded cable that is woven with a geometry to encourage current flow in all strands. The purpose being to reduce the high frequency resistance of the cable.     Load Matching The adjusting of several different quantities in the induction heater to produce the desired power and frequency to accomplish the task. Typical items adjusted are : capacitance, transformer taps, and coil taps (turns).     Load Station The portion of the heating unit that contains the tuning components (transformer & capacitors). Sometimes called the Work Station.     MIQ Coil Machined Integral Quench : A coil with a quenching circuit machined directly into the coil. The coil cooling may have its own distinct circuit or may use the quenchant to also cool the coil.     Oscillator Oscillator usually describes an entire induction power supply that uses a vacuum tube to create the high frequency current. Also usually associated with Radio Frequency induction heaters.     Parallel Tuned Tuning an induction coil by placing a capacitor in parallel with the induction coil.   Quench To cool a heated object. Quenching may be rapid or slow. The rate of quenching often effects the hardness or softness of the work piece.     Quenchant The media used to quench (cool) an object. Quenchant may be of water, oil, or polymer mixture, etc.     Radial Perpendicular to the axis or centerline.   Radiation The giving off of heat by infra-red emission. E.G. A light bulb has visible light radiation as well as infra-red (heat) radiation.     Refractory Essentially a high temperature cement (concrete). Most often refractory is silicon based, and is mixed with water to produce a substance similar to concrete for operations at high temperatures.     RF Radio Frequency   Series Tuned Tuning an induction coil by placing a capacitor in series with the induction coil.   Shunt A magnetic material, usually laminated iron, spanning from one end of an induction coil to the opposite end. The purpose is to reduce the external reluctance path of the magnetic field. By reducing the external reluctance, the efficiency is increased, inductance decreased, and stray magnetic fields are reduced.     Skid Rails Hard objects along which heated material may be pushed (skidded). Mostly associated with the water cooled stainless steel rails installed in the bottom of forging coils.     Slot Coil (or Slot Furnace) See Channel Coil     Slug A synonym for "billet".  Also an old British unit of measure of mass.   Stirring (Stirring Action) The process of moving a molten charge of metal by electromotive force. This occurs naturally in a crucible of molten metal when the induction heating magnetic fields are applied.     Susceptor A crucible that is made of a conducting material. This way, the induction heating directly heats the crucible. Items in the crucible, (non-conductors), then are heated by conduction.     Tank Circuit A capacitor and an inductor coil, in a series or parallel configuration, forming a resonant circuit. Typically referred to in the load matching portion of an induction power system.     Tripler A power supply that operates at 3 times the frequency of its own fundamental oscillator.   Work Station The area where the heating or heat assembling takes place. Often, the tuning components (transformer & capacitors) are inside of the work station. Sometimes called the Load Station.     Workpiece The object to be heated by induction.