I. Weakening of Magnetic Force
Causes
1. Long-term Use and Natural Demagnetization: During long-term use, magnets are affected by external environmental factors (such as temperature changes and vibrations), and the arrangement of magnetic domains inside them will gradually become disordered, resulting in weakened magnetic force. For example, in a high-temperature environment, the thermal motion of magnetic domains intensifies, which may disrupt the original orderly arrangement and reduce the magnetism. For neodymium-iron-boron magnets, when the working temperature exceeds a certain limit (usually around 180 degrees Celsius), obvious demagnetization will occur.
2. Interference from Reverse Magnetic Fields: If there are other magnetic field sources around the automatic door and the directions of these magnetic fields are opposite to that of the magnet's magnetic field, they may have a demagnetizing effect on the magnet. For example, in some places where there are large motors or transformers, the magnetic fields generated by these devices may interfere with the magnetic field of the automatic door magnet, causing the magnetic force to decline.
Impacts and Manifestations
1. Once the magnetic force is weakened, the automatic door may not be able to close or lock properly. For example, if the suction force of the electromagnet in the automatic door lock is insufficient to firmly hold the adsorption iron plate, the door will not close tightly, affecting safety and performance. In a magnetic lock system, if the magnetic force is not enough, the door cannot be effectively kept in a closed state and may open automatically.
II. Adsorption of Foreign Objects
Causes
1. Magnetic Adsorption Effect: Magnets have the property of adsorbing ferromagnetic substances. In the usage environment of automatic doors, there may be some ferromagnetic impurities such as iron filings and small screws. These impurities will be adsorbed on the surface of the magnets, and over time, more and more foreign objects will accumulate.
2. Installation Location Factors: If the magnets of the automatic door are installed near the ground or in the
passageway, they are more likely to come into contact with external foreign objects. For example, at the automatic doors in some factory workshops or warehouses, there may be more metal debris on the ground, which can be easily adsorbed by the magnets.
3. Impacts and Manifestations
The adsorbed foreign objects will affect the performance of the magnets. On the one hand, the foreign objects will increase the distance between the magnet and the adsorption iron plate. According to the inverse square law of the magnetic field, an increase in distance will lead to a significant decrease in suction force. On the other hand, the foreign objects may cause wear on the surface of the magnet, further affecting its performance. For example, the adsorbed metal particles may scratch the coating on the surface of the magnet during the opening and closing of the door, destroying its protective layer and accelerating the corrosion of the magnet, thus affecting the magnetic force.
III. Physical Damage
Causes
1. Collision and Impact: Automatic doors may be accidentally collided or impacted during daily use, for example, being hit by vehicles, goods, or people. Since magnets themselves may be relatively brittle (such as neodymium-iron-boron magnets), such physical impacts may cause the magnets to crack or develop cracks.
2. Improper Installation and Maintenance: During the installation or disassembly of automatic door components, if the operations are not carried out properly, the magnets may also be damaged. For example, using inappropriate tools to forcibly disassemble or install the magnets, or failing to properly fix the magnets during the installation process, resulting in the magnets shaking and colliding during the movement of the door.
Impacts and Manifestations
Physical damage will directly affect the magnetic field distribution and strength of the magnets. If the magnet is cracked, the arrangement of the magnetic domains inside it will be disrupted, and the magnetic force will decline significantly. Moreover, the fragments of the broken magnet may enter the mechanical components of the automatic door, causing the movement of the door to be blocked, resulting in problems such as jamming and abnormal noise, and may even damage other components, such as motors and transmission devices.
