Product Specification

Customized Ruby Jewel Bearings (Al₂O₃) for Precision Instruments and Watch Movements

Ruby bearings are manufactured from synthetic corundum (Al₂O₃) doped with chromium to produce their characteristic red color. With a Mohs hardness of 9 and extremely low friction characteristics, ruby jewel bearings are essential components in micro-precision mechanisms requiring long-term stability, dimensional accuracy, and superior wear resistance.

Engineered through ultra-precision grinding and optical-grade polishing (Ra < 0.3 nm), these bearings deliver outstanding performance in high-sensitivity, low-load rotational systems such as watch movements, metering instruments, aerospace navigation equipment, and scientific measuring devices.

Key Parameters

Key Features

1. Material & Mechanical Properties

• Material: Synthetic corundum (Al₂O₃), chromium-doped

• Mohs Hardness: 9 (second only to diamond)

• Knoop Hardness: ~1,800

• Surface Roughness: Ra < 0.3 nm (optical-grade polish)

• Static Friction Coefficient: 0.10–0.15 (ruby vs. steel)

• Corrosion Resistance: Resistant to acids, alkalis, oxidation, moisture

Benefits: Extremely low wear, minimal frictional loss, exceptional operational precision.

2. Performance Advantages

• High Temperature Stability: Operates from –200°C to +800°C

• Lubrication-Free Operation: Ultra-smooth crystal structure

• High Dimensional Stability: Low thermal expansion and excellent rigidity

• Long Service Life: No metallic abrasion, minimal deformation

• Non-Magnetic & Electrically Insulating: Ideal for sensitive instruments

3. Customization Options

Available in multiple precision geometries:

• Spherical jewel bearings

• Conical / V-cup bearings

• Straight-hole (through-hole) bearings

• Ring-type jewel bearings

Dimensions:

• OD: 0.8–10 mm

• Height: 0.6–5 mm

• Bore diameter: 0.05–3.0 mm (±0.001 mm tolerance)

Customization based on drawings is supported.

Application Fields

1. Watch Movements

• Balance wheel pivots

• Escapement components

• Gear train pivots
  Typical mechanical watches use 17–25 jewels to minimize friction and improve accuracy.

2. Precision Instruments

• Galvanometers

• Micrometers

• Flow meters & energy meters

• Gyroscopes & metrology equipment

Ensures low starting torque, low drift, and stable long-term accuracy.

3. Aerospace & Defense

• Inertial navigation systems

• Gyro-stabilized platforms

• High-vibration, high-temperature environments

4. Medical & Laboratory Equipment

• Dental handpieces

• Surgical instruments

• Pump mechanisms

• Blood analysis devices

5. Semiconductor & Industrial Automation

• Wafer-handling robots

• Precision stages

• Optical alignment modules

FAQ

1. Why is ruby used for precision bearings?

Because it provides extremely low friction, exceptional wear resistance, and long-term dimensional stability—far superior to metal bearings.

2. Do ruby bearings require lubrication?

In many applications, no. The polished crystal structure provides natural low-friction performance.

3. Are ruby and sapphire bearings the same?

Yes—both are Al₂O₃ single crystals. Ruby contains chromium (red color), sapphire is typically clear/blue.

4. Can ruby bearings work in harsh environments?

Yes. They resist acids, alkalis, high temperature, humidity, and vibration.

5. Are jewel bearings suitable for high-speed micro-rotation?

Yes. Their low friction and micro-scale precision make them ideal for watch escapements, micro-motors, and sensitive instruments.

Related Products

Ruby Bearings Al₂O₃ Single Crystal for Precision Instruments and Meters