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Heating Coils and Inductors

Heating Coils

Induction heating coils are used to concentrate and focus the high frequency electromagnetic field on the part to be heated.The coils are typically constructed from copper tubing and are water cooled during use.  The water cooling is necessary because the high amperage output of the power supply and matching transformer would cause the coils to heat up very rapidly without proper cooling. Coils attach to the matching transformer using 4 brass screws and 2 O rings to prevent coolant leaks.

Heating coils can be made in a wide variety of shapes and sizes. Proper design and configuration of the coil is essential for efficient part heating.  The size and shape of the coil, the number of turns in the coil, the spacing of the turns and the fit of the coil to the part must all be taken into consideration. Poorly designed coils can result in uneven, inefficient heating, producing bad parts or requiring the use of a larger, more expensive induction power supply.

Coils can be made to surround the part (helical), fit inside the part (internal), to heat a flat surface (concentric), or to come in from one side (U or C or split helical types.)  All Magneforce coils are insulated with high temperature epoxy, electrical grade epoxy powder coating or plasma spray ceramic coating for safety and to prevent arcing or short circuits during operations. Coils can also be encapsulated or encased in milled phenolic housings.

Basic Heating Coils

U shaped  coil comes around the part

The part goes inside this 2 turn 3" ID helical shaped coil with ceramic coating for high temperature protection

Flat concentric coil heats an area on the surface of a part


Inductors are similar to heating coils.  Like the coils, their purpose is to focus the high frequency field generated by the induction power supply as needed on the part to be heated.  Inductors are always custom made.  Unlike a typical heating coil they do not require the use of a matching transformer because typically inductors are larger and have more turns of copper and are able to provide the required inductance for operation of the power supply on their own.  For certain applications, the inductors can be made from heavy gauge litz wire and operate without water cooling.  When that is not possible, they are made from water cooled copper tubing formed as needed to the shape of the part. Typically a housing is constructed around the wound coil to insulate it and provide mounting points and a hub for electrical connections. 

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This specialty inductor is used to heat the drill coupling  to 500º F to thermally expand it for heat shrink attachment to the drill shaft.

This air cooled inductor is enclosed in a stainless steel housing and is used to heat a 2" diameter round barrel for a plastic extrusion operation

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