DC Motor Magnet Installation Method
★ Core Steps in DC Motor Magnet Installation
1. Determine Magnet Type
DC motor magnets are categorized into two types: permanent magnets (such as NdFeB and ferrite) and electromagnets. For permanent magnets, pay attention to the polarity markings (alternating N/S poles). For electromagnets, ensure that the winding direction matches the current flow. According to IEEE Standard 1138-2019, the operating temperature of NdFeB magnets should be ≤ 150°C. Before installation, check for demagnetization risks.
2. Pre-Installation Preparation
- Surface Treatment: Clean the inner wall of the motor stator and the magnet surface with alcohol to remove oil and dirt (recommended roughness Ra ≤ 1.6μm).
- Tools: Non-magnetic fixtures (such as aluminum alloy), adhesive (epoxy resin temperature resistance ≥ 120°C), and laser alignment equipment (accuracy ±0.01mm).
3. Positioning and Fixing
- Permanent Magnet Installation: Use the "segmented gluing method," attaching each magnet in polarity order. Maintain a curing pressure of 0.2-0.5 MPa (refer to the "Motor Process Manual").
- Electromagnet Installation: The coil must be tightly fitted to the core, with inter-turn insulation resistance ≥ 100 MΩ (GB/T 7345-2008 standard).
★ Key Parameters and Troubleshooting
1. Air Gap Control
The air gap size directly affects motor efficiency, with a typical value of 0.3-0.8 mm. For example, the air gap tolerance for a 12V micro DC motor must be within ±0.05 mm. Excessive gaps may cause magnetic flux leakage (measured data source: Nidec Technology Report).
2. Typical Troubleshooting
- Magnet Detachment: This is usually caused by insufficient adhesive curing. Curing at 25°C for 24 hours is required.
- Magnetic Field Unevenness: Use a gauss meter to check. If the local magnetic field intensity deviation exceeds 5%, the magnet position must be readjusted.
★ Installation Optimization for Different Scenarios
1. High-Speed Motors (>10,000 rpm)
A stainless steel sheath is required to prevent centrifugal force from damaging the magnets. The sheath thickness should be ≥ 1.5 mm (verified by ANSYS simulation).
2. High-Temperature Environments
Samarium-cobalt magnets (temperature resistant to 250°C) are preferred. They should be secured with high-temperature silicone (such as Dow Corning® 1-4173) to prevent carbonization of organic adhesives.
