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Various Methods to Solve the Residual Magnetism of Solenoids

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Solenoid residual magnetism refers to the phenomenon where a magnetic field still exists on the iron core of an solenoid after power is cut off. Solenoid residual magnetism can cause some adverse effects, such as:

1.       Affecting the control performance of the solenoid: The residual magnetism of the solenoid can cause residual magnetic field, which affects the control performance of the solenoid, resulting in it not working as expected.

2.       Affecting the precision of the solenoid: In certain applications, the working precision of the solenoid is crucial, and residual magnetism can affect the magnetic field strength and stability of the solenoid, which in turn affects its working precision.

3.       Affecting surrounding equipment: Residual magnetism may interfere with surrounding electronic equipment and affect their normal operation.

4.       Affecting the solenoid itself: Long-term residual magnetism can cause internal heating of the solenoid, accelerate the aging of the solenoid, and shorten its service life.

To solve this problem, the following common methods can be adopted:


1.       Short-circuit method: short-circuit the two ends of the solenoids, so that the current forms a loop in the core to eliminate the residual magnetism.

2.       Reverse excitation method: by passing a reverse current into the solenoid, a magnetic field opposite to the residual magnetism direction is generated to achieve demagnetization.

3.       Induction demagnetization method: place the solenoid in an alternating magnetic field, and use the eddy current generated by the induction effect to counteract the residual magnetism.

4.       Magnetic shielding method: add magnetic shielding material around the solenoid to isolate the magnetic field of the solenoid and eliminate the residual magnetism.

In addition, heat treatment and other processes can also solve the problem of residual magnetism in solenoid coils to a certain extent. By heating the solenoid coil to a certain temperature and then rapidly cooling it, the magnetic hysteresis effect can be destroyed, thereby eliminating residual magnetism. However, it should be noted that the heat treatment process requires strict control of temperature and time, otherwise it may damage the performance of the solenoid coil. In addition, heat treatment may have different applicability to different types of electromagnetic coils and should be selected according to the specific situation.

In addition to the above methods, there are other processing techniques and materials that can reduce the residual magnetism of solenoids, such as:


1.       Neodymium iron boron magnets: This type of magnetic steel is a common magnetic material with high magnetic properties and low residual magnetism. It is often used to manufacture permanent magnets and solenoids.

2.       Magnet design: By optimizing the design of the magnet, such as increasing the reverse magnetic current, reducing the magnet cross-sectional area, etc., the residual magnetism of the solenoid can be reduced.

3.       Magnet demagnetization: Using a special magnetic field demagnetizer to demagnetize the solenoid can eliminate the residual magnetism in the solenoid.

4.       Material surface treatment: Polishing, grinding and other surface treatments of the magnetic core of the solenoid can reduce the occurrence of residual magnetism.