Secrets To DC Motor Magnet Placement

Basic Principles of Magnet Placement
DC motor magnets aren't placed randomly! Like dancers, they must maintain precise positioning:

1. Alternating Polarity: Adjacent magnets must alternate their north and south poles to form a closed magnetic field loop.
2. Symmetrical Distribution: All magnets must be evenly spaced at equal angles to ensure balanced forces on the rotor.
3. Air Gap Control: Maintain a 0.5-2mm gap between the magnets and the rotor. Too close will cause friction, while too far will weaken the magnetic field.
4. Special Layout of Four Magnets: When a motor uses four magnets, a classic "cross" magnetic field is formed:
5. 90-degree Equal Division: Each magnet is installed 90 degrees apart, like the 3/6/9/12 o'clock positions on a clock.
6. Poles Pairing: Magnets on a diagonal line have the same polarity (e.g., both 3 and 9 o'clock have north poles).
7. Magnetic field superposition: Adjacent magnetic fields of opposite polarity form a strong interaction zone at the center, driving the rotor.
8. The butterfly effect of placement errors: A slight error can lead to a huge difference. Magnet misalignment can trigger a chain reaction:

• Increased vibration: A 1mm misalignment can cause speed fluctuations exceeding 10%.
• Reduced efficiency: A 5-degree angular deviation can reduce torque output by 8-12%.
• Double noise: Asymmetrical magnetic fields produce a harsh electromagnetic buzzing sound.
• Shortened lifespan: Long-term uneven loads can cause bearings to retire prematurely.