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When selecting deep groove ball bearings, the base part number only tells half the story. The suffix codes attached to the model numbers are critical indicators that define the seal type, internal clearance, and precision class.
At Welink Bearing, we frequently see OEM manufacturers, distributors, and maintenance technicians face premature bearing failures simply due to a misunderstood suffix. Selecting the wrong seal or clearance can lead to unexpected downtime and unnecessary cost losses.
To help you make the right choice, we have put together this comprehensive guide breaking down the most common bearing suffixes in the global market: OPEN, ZZ, 2RS, 2RZ, C3, P5, and P6. We have also aligned these with the internationally recognized ABEC precision standards for easy reference.
① Seal & Shield Suffixes: OPEN, ZZ, 2RS, 2RZ
Seals and shields are your bearing’s first line of defense against dust, moisture, and lubricant leakage. Here is how the mainstream structural types compare:
• OPEN (No Suffix / Open Type): Open bearings feature no shields or seals on either side. Because they have a fully open structure with zero extra friction, they are ideal for ultra-high-speed operations. However, they offer no protection against debris and must operate in clean, dry environments with regular re-lubrication. Typical applications include gearboxes and clean indoor industrial equipment.
• Z / ZZ (Metal Shield): A single "Z" indicates one metal shield, while "ZZ" means both sides are fitted with stamped steel non-contact shields. This non-contact design ensures low running resistance suitable for high speeds. They are factory pre-greased and offer good dustproof performance, though they are not waterproof. You will commonly find ZZ bearings in standard electric motors, fans, and power tools.
• RS / 2RS (Contact Rubber Seal): "RS" stands for a single rubber seal, and "2RS" denotes double contact rubber seals. These provide excellent waterproof, dustproof, and anti-grease leakage performance, making them perfect for harsh, humid, or heavily polluted environments. While the contact design adds slightly higher friction, they are indispensable for water pumps, agricultural machinery, and outdoor equipment.
• RZ / 2RZ (Non-Contact Rubber Seal): Bridging the gap, "2RZ" bearings feature double non-contact rubber seals. They offer a brilliant balance: the friction is close to that of ZZ metal shields (supporting high speeds), but they provide better dust and splash resistance. They are widely used in high-speed precision fans and air compressors.
Quick Comparison: Sealing Solutions
| Suffix | Structure | Waterproof | Dustproof | Friction | Best Application Scenarios |
| OPEN | Fully open | ❌ Poor | ❌ Poor | Lowest | Clean environment, re-lubrication needed, ultra-high speed |
| ZZ | Double metal shield | ❌ Poor | ✅ Good | Low | Dry indoor equipment, general motors, fans |
| 2RZ | Double non-contact rubber seal | ⭕ Splash-proof | ✅ Very Good | Low | High-speed equipment, slightly dusty/splashy environment |
| 2RS | Double contact rubber seal | ✅ Excellent | ✅ Excellent | Slightly higher | Wet, dusty, outdoor machinery, pumps |
② Internal Clearance Suffix: C3 (Critical for High-Speed & High-Temp Work)
Bearing internal clearance is the free movement space between rolling elements and raceways. The standard clearance series progresses from small to large: C2 < Normal (No suffix) < C3 < C4 < C5.
Why is C3 so highly requested?
C3 denotes an extra-large internal clearance. During high-speed rotation, bearings generate heat and expand. A normal clearance might become too tight after this thermal expansion, leading to overheating, noise, and rapid wear. C3 provides the necessary extra space to compensate for this heat expansion, ensuring stable operation.
Welink Bearing Tip: Use standard clearance for low-speed, indoor precision equipment, but default to C3 for motors, pumps, and all high-speed rotating machinery.
③ Precision Class Suffix: P5, P6 & ABEC Standards
Precision grades define a bearing's dimensional tolerance, runout, and noise level. Globally, two main standards are used: ISO precision codes (P0/P6/P5/P4) and the American ABEC standards (ABEC 1 to 9).
ISO Grade vs. ABEC Grade Cross Reference:
▪ P0 (Standard) = ABEC 1 (Commercial standard)
▪ P6 = ABEC 3 (Medium precision)
▪ P5 = ABEC 5 (High precision)
▪ P4 = ABEC 7 (Super precision)
▪ P2 = ABEC 9 (Ultra precision)
Choosing Between P6 and P5:
▪ P6 (ABEC 3): Offers higher rotational accuracy than standard P0 bearings. It provides excellent cost performance with low noise, ideal for standard industrial motors and mass OEM production.
▪ P5 (ABEC 5): Features much stricter tolerance, ultra-low vibration, and superior concentricity. This is the reliable choice for highly demanding scenarios like servo motors, machine tools, and robotics.
④ Real-World Selection Guide (Suffix Combinations)
In actual procurement, suffixes are frequently combined. Here is how to decode them for your next order:
• 6205 OPEN C3: Open type with large clearance — Perfect for high-speed gearboxes in dry environments.
• 6206 ZZ C3: Double metal shield with large clearance — The go-to standard for high-speed motor bearings.
• 6307 2RZ P6 (ABEC 3): Double non-contact rubber seal with medium precision — Ideal for high-speed precision fans.
• 6204 2RS C3 P5 (ABEC 5): Double contact seal, large clearance, high precision — Designed for high-end pumps and servo motors.
Need Help Finding the Right Bearing?
Decoding bearing suffixes doesn't have to be a guessing game. Whether you need the dustproof reliability of a ZZ or the high-speed thermal resistance of a C3, Welink Bearing is here to supply exactly what your machinery requires.
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