Details
The basic setup is an AC power supply that provides electricity with low voltage but very high current and high frequency. The workpiece to heat is placed inside an air coil driven by the power supply, usually in combination with a resonant tank capacitor to increase the reactive power. The alternating magnetic field induces eddy currents in the workpiece.
| Frequency (kHz) | Workpiece type |
|---|---|
| 5–30 | Thick materials |
| 100–400 | Small workpieces or shallow penetration |
| 480 | Microscopic pieces |
Magnetic materials improve the induction heat process because of hysteresis. Materials with high permeability (100–500) are easier to heat with induction heating. Hysteresis heating occurs below the Curie temperature where materials lose their magnetic properties. High permeability below the Curie temperature in the workpiece is useful. Temperature difference, mass, and specific heat influence the workpiece heating.
The energy transfer of induction heating is affected by the distance between the coil and the workpiece. Energy losses occur through heat conduction from workpiece to fixture, natural convection, and thermal radiation.
The induction coil is usually made of copper tubing and fluid cooled. Diameter, shape, and number of turns influence the efficiency and field pattern.
Read more about this topic: Induction Heating