Detailed description and application scope of miniature bearings

Micro bearings are small rolling bearings used in small or precision equipment, typically with an outer diameter of less than 30 millimeters (some standards are less than 20 millimeters), characterized by high precision, low friction, and durability. Here is a detailed introduction:

1. Classification

  • By type:

    • Deep groove ball bearings: the most common, capable of withstanding radial and axial loads, suitable for high-speed applications such as micro motors and hard drives.

    • Angular contact ball bearings: capable of withstanding composite loads, used for high-precision equipment such as machine tool spindles.

    • Thrust ball bearings: specializing in axial loads (such as microscope rotating platforms).

    • Cylindrical roller bearings: With strong radial load-bearing capacity, they are used in small transmission systems.

  • By material:

    • Stainless steel (440C/304): corrosion-resistant, suitable for medical or food equipment.

    • Ceramics (Si3N4/ZrO2): high temperature resistance, insulation, used in extreme environments such as aerospace.

    • Mixed ceramics: Steel ring with ceramic balls, balancing performance and cost.

2. Key characteristics

  • Accuracy level: ABEC-5/7/9 (or ISO P4/P2), with a tolerance of up to 0.001mm.

  • Rotational speed: Ceramic bearings can reach hundreds of thousands of revolutions per minute (such as dental phone bearings).

  • Load: Dynamic loads range from a few newtons to several hundred newtons (such as robot joint bearings that need to withstand repeated stresses).

3. Application Fields

  • Medical equipment: dental drill, endoscopic joint (sterile, low-noise).

  • Precision instruments: optical encoders, gyroscopes (requiring zero clearance).

  • Consumer electronics: drone motors, smartphone vibration motors (miniaturized design).

  • Industrial micro machinery: Automated robot harmonic reducer, precision gearbox.

4. Key selection points

  • Size: It needs to match the equipment space (such as the outer diameter of the watch bearing can be as small as 1.5mm).

  • Lubrication:

    • Oil lubrication: common long-lasting (such as SKF ML series).

    • Solid lubrication: molybdenum disulfide coating for vacuum environment.

    • No lubrication: Ceramic bearings are used in high-temperature and pollution-free scenarios.

  • Sealing: Rubber sealing ring for dust prevention (such as NSK ZZ sealing), or metal shielding for magnetic protection (such as MRI equipment).