What is Magnetic Flux Control?

Magnetic Flux Control Explained

For the purposes of Induction Heating, we can define Magnetic Flux Control as a generic term for the modification of an induction coil's magnetic flux by installing magnetic templates (magnetic flux controllers). Magnetic flux control using the application of non-magnetic entities, such as Faraday rings or flux robbers, are not considered when speaking about induction.

Magnetic Flux Controllers can change magnetic pattern and coil parameters significantly, and when using a controller, their application should be incorporated into the whole induction system design.

Depending on the application, controllers are called a few different names such as:

• Concentrators
• Cores
• Shields

They are given different names because a controller can play different roles such as magnetic flux concentration, shielding, and distribution.

For more information on Induction Heating, visit the Center for Induction Technology at www.fluxtrol.com.

Magneto Dielectric Materials

What exactly are magneto dielectric materials? 

To most of the world, this term doesn’t mean much.  To those of us in the realm of induction heating, magneto dielectrics have very important characteristics that apply themselves to a wide range of possibilities.

MagnetoDielectric Materials are evolving as a material class, and rapid progress is being made on improvements and understanding.  The specific properties of electrical resistivity and anisotropy have not been explored enough to allow for wide use of these materials. Research at the Center for Induction Technology has brought to light the possibility of a wide range of applications.

Essentially, magneto dielectrics are magnetic materials that don't conduct electricity.  Fluxtrol material, with enough voltage, could begin to conduct electricity, but then theoretically so will everything. Essentially, magneto dielectrics are magnetic materials that don't conduct electricity.  

There are essentially three groups of magnetic materials that can be used for magnetic flux control: laminations, ferrites, and MagnetoDielectric Materials, or MDMs.  Laminations are limited in manufacturing and frequency, a fact that is well documented.  Ferrites are used sparingly in induction heating due to their low machinability, sensitivity to thermal shock, and a low saturation flux density. 

MagnetoDielectric Materials are very well suited to fit the requirements of a wide range induction heating applications.

For more information on Induction Heating, visit the Center for Induction Technology at www.fluxtrol.com.

Seven Advantages of Using Magnetic Flux Controllers

In the world of Induction Heating engineers are always trying to make their applications more efficient and more controlled.  Using a magnetic flux controller has many distinct advantages to help us achieve our induction goals.  They are:

1. Very precise heat pattern control
2. The ability to save power or increase production rate due to the increased efficiency and better utilization of power
3. Less current demand for the same amount of power
4. Extended lifetime of the coil
5. Enhancements in power supply performance from higher coil power factor and lower current demand
6. Shielding of the part or machine components from unintended heating
7. Reduction or complete elimination of external magnetic fields, important concerning safety and electromagnetic compatibility issues

For more information on Induction Heating, visit the Center for Induction Technology at www.fluxtrol.com.

Types of Coils for Surface Heating

There are generally four types of induction heating coils for surface heating.  They are:

1. Inductor with central rod
2. Hairpin
3. Single-turn cylindrical
4. Multi-turn cylindrical

It should be noted as well that a magnetic flux controller will greatly improve induction heating coil performance.  That magnetic flux controller should contain a core and poles for optimum design.  These items are just part of creating an optimal design to achieve peak performance.

For more information on Induction Heating, visit the Center for Induction Technology at www.fluxtrol.com.

Improve Induction Heating Coil with a Magnetic Flux Concentrator

The dramatic difference between a bare induction heating coil versus using a magnetic flux controller is astounding.

In the video below, a coil with a flux concentrator is compared to just a bare coil.  

Flux concentrator material performance is advanced when it is in the best possible thermal contact with the induction coil.  This can be achieved through the use of a uniform and thin layer of a thermally conductive “medium” in–between the contact surfaces. 

 For more information on Induction Heating, visit the Center for Induction Technology at www.fluxtrol.com.

Cylindrical Melting Induction Heating Coils

There is a large variety of melting coils, ranging in sizes and designs.  The frequency range is very wide from line frequency for large furnaces to radio frequency for melting of small parts, precious metals, etc.

Big furnaces usually have lamination shunts for parameter improvement, magnetic field shielding and as construction components, while small high and middle frequency furnaces usually have no concentrators or shunts.

Flux controllers may be effectively used in a vacuum or special atmosphere furnaces mainly for shielding purposes.  Coils for melting radioactive materials should be done in a protective atmosphere.  The image below shows a cylindrical coil with a Fluxtrol A shield.  This greatly improves efficiency and power factor and allows for the use of a larger furnace in the same chamber.

 For more information on Induction Heating, visit the Center for Induction Technology at www.fluxtrol.com.

Improved Induction Heating Coil Design

It is difficult to make a coil that does not work at all - Anatoly Smimov, old coil master, 1958

Some of us like to say "It's difficult to make a coil that doesn't work, but it's also difficult to make a coil that fits or exceeds modern expectations."

The fact is, magnetic flux control plays a key role in optimal coil design.

Original induction coils for plastic coating applications of stub shafts produced improper temperature distribution and was subject to mechanical damage.

The modern potted coil with a local Fluxtrol controller and stainless steel protective cap provides excellent heat pattern control, improves the mechanical strength of the coil and greatly improves efficiency.

For more information on Induction Heating, visit the Center for Induction Technology at www.fluxtrol.com.