Induction Heating Glossary

Eldec’s engineers explain common induction heating-related terms and phrases

Atmosphere – Also called Controlled Atmosphere -

A controlled (typically inert) atmosphere in which the heating process is performed; an inert atmosphere can be used to keep oxidation from occurring.

Audio Frequency (AF) -

See Medium Frequency

Bonding -

The curing of an adhesive using heat to join two or more similar or dissimilar materials.

Brazing -

A process in which a filler metal is melted and flowed into a joint to join two or more metal items at a high temperature. Brazing differs from welding in that brazing does not involve melting of the pieces being connected. Brazing differs from soldering in that soldering is performed at a lower temperature.

Brazing Alloy -

The filler material used to create the joint when brazing. These alloys vary in composition for a wide variety of melting points and other physical properties.

Brazing Pistol -

A pneumatic tool (with an induction coil incorporated into it) that is designed to squeeze and heat base materials for the purpose of brazing. Read more about eldec’s brazing pistols.

Cable Box -

See Heating Cable Box

Capacitor -

An electrical device used to store energy

Chiller -

An air-to-water heat exchanger with a refrigeration circuit used to provide cooling fluid (typically water)

Coax Cable / Coax Transformer -

An assembly consisting of a cable/hose bundle and a transformer (handheld or mounted) to conduct current and carry cooling fluid from an Induction Generator to a coil or heating cable box.

Coil -

Sometimes called Inductor, Induction Coil, Induction Wand, Induction Welding Head, etc. Tool used to create an alternating magnetic field, which in turn induces an alternating electrical current inside a metallic or other conductive part for the purpose of heating. Coils are designed specifically for the application in which they are being used; they are typically made of copper, and may or may not have cooling channels incorporated. eldec induction heating coils are made in the USA at our facility in Auburn Hills, MI.

Types include, but are not limited to Clamshell, Gleichfeld Inductor / Pretzel Coil, Hairpin Coil, ID Heading Coil, OD Heating Coil, Pancake Coil, etc.

Concentrator -

A magnetic material used to direct or concentrate the magnetic field in a specific direction.

See also Ferrotron and Laminations

Connection Ring -

Common rings that transmit each of the three phases from the stator bars to the output of a generator

Controlled Atmosphere -

See Atmosphere

Copper Bar Rotor -

A rotor consisting of steel laminations with copper bars connected to copper end rings; usually assembled via a brazing process

Coupling -

The electro-magnetic interaction between the induction coil and the metallic workpiece

Coupling Distance -

The distance between the induction coil and the workpiece

Curing -

The process of cross-linking a polymer (such as an adhesive, epoxy, or paint) resulting in a toughening or hardening of the material. This is commonly done through heat or chemical additives.

DA (Dual Output) -

This is a Generator with two sequential outputs; meaning only one output can be used at a time.

Decouple -

Increasing the coupling distance between an induction coil and a workpiece in order to minimize the heating effect in a specific location.

DI Water -

Also Called De-Ionized Water.Water that has had almost all of its mineral ions removed. WARNING: This type of water should NEVER be used for cooling in your induction power supply as it will damage the equipment over time.

Distilled Water -

Water that has been boiled and the steam re-captured to demineralize (not de-ionize)

EV -

Electric Vehicle

Faraday’s Law of Induction -

A basic law of electromagnetism that predicts how a magnetic field will interact with an electric circuit to produce an electromotive force. It states that the induced electromotive force in any closed circuit is equal to the negative of the time rate of change of the magnetic flux enclosed by the circuit.

Ferrotron -

Not to be confused with Laminations.

A soft magnetic composite material designed to act as a concentrator for an induction coil; able to be machined into complex shapes

Flux -

A chemical cleaning agent used to prevent oxides from forming during the brazing process

Foot / Coil Foot -

The end of the coil that connects to the coax transformer

Generator -

Also called Power Supply Equipment used to convert main AC power (low frequency–50 or 60 Hz) to a higher frequency for the purpose of induction heating. eldec induction heating systems are assembled in the USA at our facility in Auburn Hills, MI.

GMD (Gearless Mill Drive) -

A large electric motor used in the mining industry

Handheld Transformer -

A Coax Transformer sized small enough to be manipulated or held in hand. Larger transformers require mounting.

Head / Coil Head -

The part of the coil that creates the desired magnetic field for induction heating

Heating Cable -

A flexible cable used to inductively heat a workpiece. Heating cables cannot withstand temperatures as high as typical induction coils as the cables are not actively cooled. Up to 25kW can typically be used on one heating cable.

Heating Cable Box -

A box located at the end of a coax cable for connecting heating cables

High Frequency Induction Generator (HF) -

Also called Radio Frequency

Frequency range from 150 kHz up to 350 kHz


Heating, Ventilating, and Air Conditioning (and Refrigeration)

Hybrid -

A vehicle that uses two distinct sources of power; typically an internal combustion engine and an electric motor.

Hydro -

Referring to hydro-electric power generation where electricity is generated from falling or fast moving water

Impedance -

A measure of electrical resistance within an induction coil. It is also known as the inductance and is a ratio of the voltage to the rate of change of current. The unit of measure is the micro henry (µH).

Induction Coil / Induction Wand / Inductor -

See Coil

Infield -

An induction coil with a field directed toward the inside of the coil diameter; this coil would be positioned to heat the outside diameter of a part.

Joining -

The bringing together of two or more similar or dissimilar materials to form a single assembly or structure by way of a mechanical or metallurgical bond

Laminations (Lams) -

Not to be confused with Ferrotron

Thin sheets of special electrical steel that are stacked linearly to act as a concentrator for an induction coil

Leads / Coil Leads -

Conductors used to carry current from the coil foot to the coil head

Load / Workpiece -

Customer part to be heated

Matching Range -

A specific range of coil impedance values that will run on a specific Generator. A Generator’s matching range can be broadened by use of a series / parallel switch.

Medium Frequency Induction Generator (MF) -

Also called Audio Frequency.

Frequency range from 8 kHz up to 40 kHz


See Generator

Medium Frequency Generator

Motor Housing -

The outer casing of a motor that is used for mounting, grounding, and for protection from moving parts

Outfield -

An induction coil with a field directed outward (to the outside of the coil diameter); this coil would be positioned to heat the inside diameter of a part.

Overdrive -

The ability of a Generator (not on every Generator) to provide an extra boost of power for a short duration. For example, an MFG 50 (80) is a 50kW Medium Frequency Generator that would have the ability to overdrive the output power to 80kW for 2-3 minutes.

Power Supply -

See Generator

Radio Frequency (RF) -

See High Frequency

Retaining Ring -

Large steel or stainless steel ring shrunk-fit on a turbo generator rotor to retain the end windings of the field coil during operation

Rotor -

The rotating part of an electric or induction motor

SCR / Short Circuit Ring -

Solid rings that attach to the ends of all of the longitudinal conductors in a rotor

Series / Parallel Switch -

An available option for eldec Generators that broadens the range of coil impedances that can be used with the Generator

Skin Depth -

The depth at which the current density has fallen to approximately 37% of the current density at the surface of the workpiece. At higher frequencies, the skin depth is smaller.

Skin Effect -

The tendency for an alternating current to be distributed within a workpiece such that the surface of the workpiece has the highest current density; the current density then tapers off as the depth into the conductor increases. Skin effect is greater with high frequency applications.

Squirrel Cage Induction Motor -

See Copper Bar Rotor

Stator -

The stationary part of an electric or induction motor or generator used to keep the magnetic field aligned

Symmetric Output -

This is a Generator with two simultaneous outputs that are tied to a single output

TWIN Output -

This is a Generator with two simultaneous outputs that are controlled independent of one another.

Warming -

The process of increasing the temperature of a workpiece for polymer curing, welding pre-heating or post-heating, annealing, shrink-fitting, etc.

Welding -

A fabrication process in which two or more metal items are joined by melting and fusing the base metals together as well as melting a filler material. Welding differs from brazing and soldering in that brazing and soldering do not involve melting of the pieces being connected.