Product Specification

Ruby Through-Hole Bearing – Precision Jewel Bearing for High-Accuracy Instruments

The Ruby Through-Hole Bearing is a precision-engineered jewel component made from synthetic ruby (single-crystal Al₂O₃ with Cr doping). Known for its exceptional hardness, low friction, and excellent dimensional stability, this bearing is widely used in measuring instruments, micro-mechanical assemblies, watches, and high-precision scientific equipment.

Thanks to its wear resistance, chemical inertness, and long service life, the ruby through-hole bearing has become a preferred solution for applications where precise rotational movement and minimal friction are essential.

Product Features

1. Outstanding Hardness & Wear Resistance

Ruby, with a hardness of Mohs 9, resists abrasion, surface deformation, and dimensional drift even under continuous rotational loading.

• Maintains long-term accuracy

• Extremely low material wear

• Suitable for high-frequency micro-rotors and pointer mechanisms

2. Ultra-Smooth Low-Friction Rotation

The polished inner bore provides:

• Very low friction coefficient

• Smooth and stable rotational behavior

• Improved repeatability of measurement instruments

This makes it ideal for dial indicators, precision meters, and sensitive rotational modules.

3. High Thermal & Chemical Stability

Ruby is stable in harsh environments:

• Heat resistance above 1000°C

• Chemical inertness against acids and common solvents

• No oxidation or aging over long-term use

Suitable for laboratories, cleanrooms, and industrial environments.

4. Customizable Precision & Dimensions

We support complete customization to meet instrument and OEM requirements:

• Inner hole diameter: 0.2–20 mm

• Outer diameter: 1–50 mm

• Thickness: 0.2–10 mm

• Inner/outer chamfering

• Optical polishing or matte finish

• Special shapes (ring, crown, stepped hole, tapered hole)

Manufacturing Technology

Ultrasonic Drilling / Fine CNC Machining

Creates precise through-holes with minimal edge chipping and excellent roundness.

High-Precision Lapping & Polishing

• Bore roundness: ≤0.01 mm

• Surface roughness (Ra): <0.02 μm

• Excellent dimensional repeatability

Ensures smooth, friction-free operation in micro-mechanical systems.

Crystal Orientation Control

Single-crystal ruby allows precise control of physical properties, improving stability during long-term operation.

Applications

The ruby through-hole bearing is widely adopted in industries that require ultra-precise rotational components:

Precision Instruments

• Dial indicators

• Micrometers

• Analytical instruments

• Balance and scale mechanisms

Measuring & Control Systems

• Sensor modules

• Pointer mechanisms

• Micro-actuators

Watchmaking & Micro-Mechanics

• Mechanical watch jewel bearings

• Micro-rotor modules

• Timekeeping movement supports

Medical & Scientific Equipment

• Lab automation

• Sample handling mechanisms

• Optical positioning assemblies

Electronics & Semiconductor

• Precision guiding components

• High-stability rotating elements

Typical Specifications (Customizable)

Advantages of Our Ruby Bearings

• 10+ years of jewel bearing manufacturing experience

• Ultra-precision machining and polishing capability

• Clean chamfering and custom geometries supported

• Fast sampling and stable mass production

• 100% quality inspection (roundness, flatness, roughness)

FAQ

Q1: Can you make very small holes such as 0.2–0.5 mm?

Yes, micro-holes down to 0.2 mm are available depending on thickness and design.

Q2: Do ruby bearings provide lower friction than metal bearings?

Yes. Ruby offers extremely low friction and does not generate metal particles, making it better for precision and cleanroom environments.

Q3: Can I order special shapes or stepped holes?

Absolutely. We support stepped, tapered, crown-shaped, oval, and custom geometries.

Q4: Are ruby and sapphire interchangeable?

Yes, both are corundum materials. Ruby offers higher visibility and is often preferred in mechanical watches and precision indicators.