1. Electromagnetic induction
Alternating current in the coil creates a time-varying magnetic field. When a conductive workpiece couples with that field, voltage and circulating eddy currents are induced in the part.
Induction heating fundamentals
How induction heating works
An induction heating system uses alternating current in a coil to create a changing magnetic field. That field induces electrical currents in a conductive workpiece, generating heat directly within the material.
Electromagnetic inductionChanging fields induce current
Skin effectFrequency influences current depth
Heat conductionEnergy spreads through the workpiece
Three connected principles
From magnetic field to useful heat
These principles explain why material, frequency, coil geometry and time have such a strong influence on the final temperature pattern.
2. Resistance and skin effect
The induced current generates heat through electrical resistance. Alternating current tends to concentrate near the surface; higher frequencies generally produce shallower current penetration.
3. Heat transfer
Heat generated in the electrically active region spreads through the workpiece by conduction. Heating time, thermal conductivity, geometry and heat loss shape the final temperature distribution.
The induction circuit
Power supply, matching network, coil and workpiece
The generator converts utility power into controlled alternating current. The resonant circuit and workhead deliver that current to the coil, which couples energy into the part.
Induction power supply
Converts incoming electrical power into controlled AC at the frequency and power required by the application.
View power supplies
Matching and resonant components
Capacitors and transformers help match the generator to the coil and load so current can be delivered efficiently within the operating range.
Induction coil
The coil creates the magnetic field. Its shape, turn direction, spacing, coupling and cooling are designed around the workpiece.
Explore coil designFrequency and heating depth
Frequency changes where current concentrates
There is no universally “best” induction frequency. The appropriate range depends on material properties, dimensions, required depth, coil configuration and heating time.
| Frequency tendency | Current penetration | Typical application direction |
|---|---|---|
| Higher frequency | Shallower concentration near the surface | Smaller parts, localized surface heating, precision brazing and soldering |
| Middle frequency | Intermediate penetration | General industrial heating, brazing, shrink fitting and heat treatment |
| Lower frequency | Deeper current penetration | Larger cross-sections, billet heating, forging and through-heating |
These are directional tendencies, not fixed selection rules. Heating time allows thermal conduction to change the final temperature profile.
Material response
Different materials do not heat the same way
Electrical resistivity, magnetic permeability, thermal conductivity and heat capacity affect how a workpiece couples and how quickly its temperature changes.
Ferromagnetic steels can couple strongly below their Curie temperature and may receive additional heating associated with magnetic losses. Nonmagnetic conductive materials—including copper, brass and aluminum—can also be heated, but the required frequency, coil and power may differ substantially.
Process variables
What controls the heating result?
Induction is a system-level process. Changing one variable can change power transfer, temperature uniformity and cycle performance.
Material
Electrical and thermal properties, magnetic state and starting condition.
Geometry
Mass, cross-section, edges, holes, neighboring features and heat sinks.
Coil and coupling
Shape, position, turn spacing, clearance and magnetic flux control.
Power and time
Energy rate, frequency, ramp, soak, motion and total heating duration.
Ready to apply the theory to a real part?
Describe the material, dimensions, target temperature, heating time and production goal. We can help translate those requirements into a practical induction approach.
Induction heating fundamentals
How induction heating works
An induction heating system uses alternating current in a coil to create a changing magnetic field. That field induces electrical currents in a conductive workpiece, generating heat directly within the material.
Electromagnetic inductionChanging fields induce current
Skin effectFrequency influences current depth
Heat conductionEnergy spreads through the workpiece
Three connected principles
From magnetic field to useful heat
These principles explain why material, frequency, coil geometry and time have such a strong influence on the final temperature pattern.
1. Electromagnetic induction
Alternating current in the coil creates a time-varying magnetic field. When a conductive workpiece couples with that field, voltage and circulating eddy currents are induced in the part.
2. Resistance and skin effect
The induced current generates heat through electrical resistance. Alternating current tends to concentrate near the surface; higher frequencies generally produce shallower current penetration.
3. Heat transfer
Heat generated in the electrically active region spreads through the workpiece by conduction. Heating time, thermal conductivity, geometry and heat loss shape the final temperature distribution.
The induction circuit
Power supply, matching network, coil and workpiece
The generator converts utility power into controlled alternating current. The resonant circuit and workhead deliver that current to the coil, which couples energy into the part.
Induction power supply
Converts incoming electrical power into controlled AC at the frequency and power required by the application.
View power suppliesMatching and resonant components
Capacitors and transformers help match the generator to the coil and load so current can be delivered efficiently within the operating range.
Induction coil
The coil creates the magnetic field. Its shape, turn direction, spacing, coupling and cooling are designed around the workpiece.
Explore coil designFrequency and heating depth
Frequency changes where current concentrates
There is no universally “best” induction frequency. The appropriate range depends on material properties, dimensions, required depth, coil configuration and heating time.
| Frequency tendency | Current penetration | Typical application direction |
|---|---|---|
| Higher frequency | Shallower concentration near the surface | Smaller parts, localized surface heating, precision brazing and soldering |
| Middle frequency | Intermediate penetration | General industrial heating, brazing, shrink fitting and heat treatment |
| Lower frequency | Deeper current penetration | Larger cross-sections, billet heating, forging and through-heating |
These are directional tendencies, not fixed selection rules. Heating time allows thermal conduction to change the final temperature profile.
Material response
Different materials do not heat the same way
Electrical resistivity, magnetic permeability, thermal conductivity and heat capacity affect how a workpiece couples and how quickly its temperature changes.
Ferromagnetic steels can couple strongly below their Curie temperature and may receive additional heating associated with magnetic losses. Nonmagnetic conductive materials—including copper, brass and aluminum—can also be heated, but the required frequency, coil and power may differ substantially.
Process variables
What controls the heating result?
Induction is a system-level process. Changing one variable can change power transfer, temperature uniformity and cycle performance.
Material
Electrical and thermal properties, magnetic state and starting condition.
Geometry
Mass, cross-section, edges, holes, neighboring features and heat sinks.
Coil and coupling
Shape, position, turn spacing, clearance and magnetic flux control.
Power and time
Energy rate, frequency, ramp, soak, motion and total heating duration.
Ready to apply the theory to a real part?
Describe the material, dimensions, target temperature, heating time and production goal. We can help translate those requirements into a practical induction approach.