The Function of the Iron Core in a Coil

The Function of the Iron Core in a Coil

The purpose of adding an iron core or a magnetic core to a coil is to increase the magnetic field strength. The iron core can concentrate the magnetic field lines around the coil and make them all flow through the iron core. Without an iron core, the magnetic induction between the coils will decrease. Just like in an electric circuit, the magnetic circuit always seeks the path with lower magnetic resistance (equivalent to resistance in an electric circuit). The magnetic resistance of the iron core is much smaller than that of air, so the magnetic flux mainly passes through the iron core. When an iron core is inserted into an energized solenoid, the iron core is magnetized by the magnetic field of the energized solenoid. The magnetized iron core also becomes a magnet. In this way, due to the superposition of the two magnetic fields, the magnetism of the solenoid is significantly enhanced. To make the electromagnet stronger, the iron core is usually made into a U-shaped (horseshoe-shaped). However, it should be noted that the winding directions of the coils on the U-shaped iron core are opposite. One side is wound clockwise, and the other side must be wound counterclockwise. If the winding directions are the same, the magnetization effects of the two coils on the iron core will cancel each other out, and the iron core will not exhibit magnetism. The iron core of an electromagnet is made of soft iron instead of steel. Otherwise, once the steel is magnetized, it will retain its magnetism for a long time and cannot be demagnetized. Then, the strength of its magnetism cannot be controlled by the magnitude of the current, resulting in the uncontrollability of the magnetism of the electromagnet. Dongguan Golden Eagle Coil&Plastic Co., Ltd. has been engaged in the R&D and production of coils for more than 20 years and has accumulated rich experience in the coil industry.