The Function of Adding an Iron Core to a Coil

The Function of Adding an Iron Core to a Coil

The function of adding an iron core to a coil is to enhance the magnetic field strength. The iron core can concentrate the magnetic field lines around the coil to flow through itself. Without an iron core, the magnetic induction between coils will decrease. Similar to an electric circuit, a magnetic circuit always seeks the path with lower magnetic resistance (analogous to electrical resistance). Since the magnetic resistance of iron is much lower than that of air, the magnetic flux primarily flows through the iron core.

When an iron core is inserted into a current-carrying solenoid, the core is magnetized by the magnetic field of the solenoid. The magnetized iron core itself becomes a magnet, and the superposition of the two magnetic fields significantly strengthens the magnetism of the solenoid. To further enhance the magnetism of an electromagnet, the iron core is typically shaped into a U-shape (horseshoe shape).

It should be noted that the windings on the U-shaped iron core must have opposite directions—one clockwise and the other counterclockwise. If the winding directions are the same, the magnetization effects of the two coils on the iron core will cancel each other out, making the core non-magnetic. The iron core of an electromagnet should be made of soft iron rather than steel. If steel is used, it will retain magnetism permanently after magnetization and cannot be demagnetized, making it impossible to control the magnetic strength by adjusting the current, thus rendering the electromagnet's magnetism uncontrollable.

Dongguan Golden Eagle has specialized in coil production and R&D for over 20 years, accumulating rich experience in the coil industry.