Ceramic Bearings

I. Part-Number Coding (GB/T 272 plus industry-standard suffixes)

Basic structure: Type code + dimension-series code + bore code + material code + seal / tolerance code

1. Core Material Codes

HC: Hybrid-ceramic (Si₃N₄ silicon nitride balls, steel inner-/outer-rings), example 6205/HC

CE: Full-ceramic (ZrO₂ zirconia / Si₃N₄ silicon nitride, fully ceramic construction), example 6205CE

Si₃N₄: Silicon nitride (high-temperature resistance up to 1200 °C, high hardness, electrically insulating)

ZrO₂: Zirconia (corrosion-resistant, good toughness, electrically insulating)

2. Type Codes (identical to steel bearings)

6: Deep-groove ball bearing (most widely used)

7: Angular-contact ball bearing

N: Cylindrical roller bearing

MR: Miniature bearing (e.g. MR105 = 5 × 11 × 4)

3. Bore Code (mm)

00 = 10 mm; 01 = 12 mm; 02 = 15 mm; 03 = 17 mm

Code ≥ 04: Last two digits × 5 (e.g. 6205 → 25 mm bore)

4. Seal / Tolerance Suffixes

2RS: Double-sided contact-type seals; Z: Metal shield

P4 / P5: Tolerance classes (P4 represents higher precision)

C3: Increased internal clearance (for high-speed / high-temperature applications)

II. Common Specifications (d × D × B, mm)

1. Deep-Groove Ball Bearings (Series 6, general-purpose)

Miniature size  604CE: 4 × 12 × 4 (full-ceramic ZrO₂)  608/HC: 8 × 22 × 7 (hybrid with Si₃N₄ balls)

Small-size (20-50 mm bore)

Part-Number	Bore d	Outer Diameter D	Width B	Type
6202/HC	15	35	11	Hybrid-ceramic
6205CE	25	52	15	Full-ceramic
6306-2RS/HC	30	72	19	Hybrid-ceramic, sealed

2. Full-Ceramic vs Hybrid-Ceramic

Full-ceramic (CE): Inner ring, outer ring and balls made of ZrO₂ / Si₃N₄. Non-magnetic, electrically insulating, resistant to strong acids and alkalis, high-temperature resistant. Applied in chemical, medical and semiconductor industries.  Hybrid-ceramic (HC): Steel rings with Si₃N₄ balls. High-speed capability, low heat generation, electrically insulating, cost-effective. Used for motors, machine-tool spindles and turbo-machinery.

III. Key Selection Guidelines

1. Material selection – Corrosion-prone environments / electrical-insulation requirement: Choose ZrO₂ full-ceramic; (CE)High-speed / high-temperature conditions: Choose Si₃N₄ hybrid-ceramic (HC);Cost-sensitive applications: Hybrid-ceramic delivers best cost-performance
2. Sealing: Add suffix 2RS for dusty or humid operating conditions
3. Internal clearance: Select C3 clearance for high-speed / high-temperature service