"We try to give our customers a clear idea of what induction heating is, and how this non-contact method of heating works so fast. The alternating current in the work coil sets up an electromagnetic field that creates a circulating current in the work piece. This circulating current in the work piece flows against the resistivity of the material and generates heat. It's really that simple!"
Induction heating is a method of providing fast, consistent heat for manufacturing applications which involve bonding or changing the properties of metals or other electrically-conductive materials. The process relies on induced electrical currents within the material to produce heat. Although the basic principles of induction are well known, modern advances in solid state technology have made induction heating a remarkably simple, cost-effective heating method for applications which involve joining, treating, heating and materials testing.
A Typical Induction Heating System (click here!)
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The basic components of an induction heating system are an AC power supply, induction coil, and workpiece (material to be heated or treated). The power supply sends alternating current through the coil, generating a magnetic field. When the workpiece is placed in the coil, the magnetic field induces eddy currents |
Operating Frequency (click here!)
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There is a relationship between the frequency of the RF field and the depth to which it penetrates your workpiece; low frequencies (up to 30kHz) are effective for thicker materials requiring deep heat penetration, while higher frequencies (100 to 400kHz) are effective for smaller parts or shallow penetration. The higher the frequency, the higher the heat rate. |
Magnetic Vs. Non-Magnetic Materials (click here!)
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Due to the effects of hysteresis |
Depth of Penetration (click here!)
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The induced current flow within the part is most intense on the surface, and decays rapidly below the surface. So the outside will heat more quickly than the inside; 80% of the heat produced in the part is produced in the outer "skin". This is described as the "skin depth" of the part. The skin depth decreases when resistivity decreases, permeability increases or frequency increases. |
Coupling Efficiency (click here!)
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Coupling refers to the proportional relationship between the amount of current flow in the workpiece and the distance between the workpiece and the coil. Close coupling generally increases the flow of current and therefore increases the amount of heat produced in the workpiece. |
The Importance of Coil Design (click here!)
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The induction coil, made from copper tubing, is water-cooled. The size and shape of the coil (single or multiple turn; helical, round or square; internal or external) follows the shape of your workpiece and variables of your process so that the proper heat pattern is achieved and the efficiency of the induction system is maximized. You can read more about this important aspect of induction heating in our free tech note, "Coil Design and Fabrication". |
Applied Power (click here!)
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The system generates an RF field in the induction coil,producing a magnetic field around your workpiece. System output determines the relative speed at which the workpiece is heated: a brazing process accomplished with a 3 kW system could be completed more quickly with a 5 kW system. However, additional power capability may increase the system's, size and weight and utility requirements; larger ones require 3-phase electrical connections and facilities for water cooling. For more information about RF power supplies, go to our Product Catalog. |
Your Power Requirements (click here!)
For your application, you must consider: the degree of temperature change required, the mass, specific heat and electrical properties of the workpiece, the coupling efficiency of the coil design and thermal losses due to conduction of heat into workpiece fixturing, convection and radiation.
NOTE: our Applications Lab Engineers have extensive experience in balancing these variables and are ready to assist you - keep reading!
Will Induction Work For Your Application? (click here!)
At our Applications Lab in Scottsville, NY, we are constantly evaluating and developing new uses for precision induction heating with our advanced solid state technology. We invite you to contact us about sending samples of your parts to our lab for a NO CHARGE evaluation and system recommendation. We may already have a solution for you! Send us your parts, describe your process, tell us what is most important to you, and we will provide you with our best advice. For more information, visit our Applications Laboratory page or send us an e-mail with your questions. We'll look forward to working with you on a precision heating solution!