Induction heating of non-magnetic metal?

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SUMMARY

The forum discussion centers on the challenges of induction heating non-magnetic metals, specifically aluminum, using a 100W Royer oscillator operating at 200kHz. While the device successfully heats steel to incandescence, aluminum remains unaffected, raising questions about the role of eddy currents and magnetic hysteresis in heating efficiency. The user notes that larger steel pieces cause the coil and MOSFETs to heat up, while aluminum results in a hot coil but cold transistors, indicating a frequency mismatch for optimal heating. The discussion highlights the importance of material properties and frequency in induction heating applications.

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  • Understanding of induction heating principles
  • Familiarity with Royer oscillator circuits
  • Knowledge of eddy currents and magnetic hysteresis
  • Basic electronics, particularly MOSFET operation
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Engineers, hobbyists, and researchers involved in induction heating applications, particularly those working with non-magnetic metals like aluminum.

Artlav
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I'm experimenting with induction heating, and made a simple ~100W device.
Royer oscillator type, 200kHz frequency.
It readily heats a steel blade to the point of incandescence.

However, a piece of aluminium of a similar size doesn't even get warm.
I understand that magnetic hysteresis helps a lot in iron and other magnetic materials, but i thought eddy currents do their job too, so zero result on aluminium seems just wrong.

Is that normal?
I've seen videos of 2kW units melting aluminium, how is that possible if at 20 times less it's not even heating up?

Also,
With big steel piece the coil is hot and MOSFETs are getting hot.
With small steel piece the coil stays warm, but transistors still heat up.
But, with aluminium the coil is getting hot rather quickly, and the transistors stay completely cold.
When empty, it behaves like with aluminium.
Oscillations are going in all cases.

How does that happen (coil hot, transistors cold)?
 
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You didn't mention frequency. The optimum frequency depends on the permitivity of the material.
 

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