Brushless DC (BLDC) motor bearings, also known as electric motor bearings or motor bearings, are specialized bearings designed specifically for use in electric motors and drives. Bearings support and guide the motor shaft while allowing it to rotate smoothly. They also withstand radial and axial loads from internal motor components. The most common types of bearings used in electric motors are ball bearings, sleeve bearings, journal bearings, and fluid film bearings. BLDC motors typically utilize ball bearings.

When selecting bearings for BLDC motors, engineers must consider factors such as:

Radial Internal Clearance

Insufficient clearances can lead to noise and premature failure, especially in cold operating environments. As temperature drops, the outer ring contracts, reducing internal clearance. Tight machining tolerances further compound this issue. The resulting metal-to-metal contact causes friction, vibration, and noise. Interference fits during installation can also decrease clearances.

Recommended Actions:

• Closely control precision tolerances, particularly inner and outer race dimensions, to maintain adequate clearance across operating temperature range.
• Increase radial internal clearance to 8-15 μm to allow for thermal contraction of outer ring at low temperatures. However, clearances that are too loose can also cause vibration issues at high temperatures.
• Control preload during installation to prevent over-tightening bearings.

Lubricant Characteristics

Thicker fluids impede centrifugal lubrication flow in the rolling elements. Such lubricants are also more prone to churning losses during transport, which can accelerate bearing wear.

Recommended Actions:

• Select low-viscosity lubricants designed specifically for low operating temperatures.

Concentricity Between Shaft and Inner Ring

Eccentric mounting can overload a portion of the rolling elements, causing uneven and accelerated wear.

Recommended Actions:

• Ensure concentricity between shaft and inner ring during installation to evenly distribute loads.

By considering these key factors, engineers can select bearings optimized for the operating conditions of the particular BLDC motor. Precise bearing selection and installation is crucial for reliable performance across a wide temperature range.