Miniature ball bearings are designed for compact applications, offering smooth operation, low friction, and low maintenance. Ideal for high-speed and precision requirements. Common applications include robotics, medical equipment, electronics, aerospace and aviation, automotive, precision instruments, hobby and RC models, and more.
| d | 8 mm | Bore diameter |
| D | 28 mm | Outside diameter |
| B/B1 | 9 mm | Width |
| d1 ≈ | 14.5 mm | Shoulder diameter inner ring |
| D1 ≈ | 21.3 mm | Shoulder diameter outer ring |
| r | 0.3 mm | Chamfer |
| 7 pcs | Ball qty | |
| 4.7625 mm | Ball diameter | |
| ≈m | 28.1 g | Weight |
| Cr | 4550 N | Basic dynamic load rating |
| C0r | 1970 N | Basic static load rating |
| 28000 r/min | Max speed (Grease) | |
| 34000 r/min | Max speed (Oil) | |
| P0(ABEC-1) | Tolerane | |
| CN | Clearance |
| Open | Sealing | |
| None | Locating feature outer ring | |
| 52100 | Ring Material | |
| 52100 | Ball Material | |
| SPCC | Cage Material |
| NMB | NHBB | NSK/ISC | NTN | BARDEN | RMB | MPB(TIMKEN) | SKF | ADR | GRW | EZO | DYNAROLL | FAFNIR | FAG | Gost | others |
| 638 | 638 | 38 | 638 |
