NMB Ball Bearing Numbering Guide
Published: Apr 25, 2026
Engineering Team
Minebea employs a distinctive identification structure where the complete part number is formed by combining a Base Part Number with specific Specifications. Unlike the JIS system, which adheres to the regulations set forth in the JIS 1513 standard, the NMB numbering convention is proprietary and unique to our brand.
| Base Part Number | ||
|---|---|---|
| Ring & Ball Material | Series | Size |
| Details: Page 15 | - | - |
| DD | R- | 1560 |
| Base Part Number | ||
| Enclosure | Noise Grade/Special Feature | Retainer |
| No Code: SAE52100 or Equivalent Bearing Steel DD: Martensitic Stainless Steel CE: Outer/Inner Ring: SAE52100 or Equivalent Bearing Steel Ball: Ceramic | Metric Radial Ball Bearing: R-(RF-): R-Series (Flanged) L-(LF-): L-Series (Flanged) A-: Ultra Thin Type RNR-: R-Series with External Retaining Ring LNR-: L-Series with External Retaining Ring Inch Radial Ball Bearing: RI-: Inch Type (R-): Used for particular Inch Types RIF-: Inch Flanged Type Thrust Ball Bearing: T- Special Type: ZB-: Integrated Shaft Bearing AS-: Special Type | Derived from the outside and bore diameters. Ex: Metric Size 1560: OD 15mm, Bore 6mm Ex: Inch Size 418: OD 4/16 inch, Bore 1/8 inch X: If the bearing design is different from basic, this comes after basic symbols. Ex: 1560X2 OD = 15 mm Bore = 6 mm Internal Design = X2 Type |
| Details: Page 16 | - | Details: Page 17 |
| ZZ | MT | R |
| No Code: Open Z: Metallic Shield (Fitted with Snap-Ring) H: Metallic Shield (Pressed) K: Metallic Shield (Staked) D: Rubber Seal (Contact) S: Rubber Seal (Non-Contact) Note: Double symbol indicates enclosures on both sides (e.g. ZZ, DD). | No Code: Standard MT: Electric motor quality (For extremely noise sensitive applications) SD: Special Design W: Wider width than standard Y: Narrower width than standard EE: Extended Inner Ring | R: Ribbon Retainer (Steel) H: Crown Retainer (Steel) MN: Plastic Retainer (Glass Fiber reinforced) Note: Other materials are also available for the plastic retainer. |
| Bearing Specification | |||
|---|---|---|---|
| ABEC Grade | Radial Play | Lubricant | Grease Fill Amount |
| Details: Page 21 | Details: Page 28 | Details: Page 40 | Details: Page 40 |
| A1 | P25 | LY121 | L |
| A1: ABEC grade 1 A3: ABEC grade 3 A5: ABEC grade 5 A7: ABEC grade 7 | P13: .0001"~.0003" (2.5μm~ 7.5μm) P24: .0002"~.0004" (5.0μm~ 10.0μm) P25: .0002"~.0005" (5.0μm~ 12.5μm) P58: .0005"~.0008" (12.5μm~ 20.5μm) Note: Letter "P" followed by two to four numbers indicates the radial play range in ten thousandths of an inch. Ex: P25 indicates radial play of .0002" to .0005" (5.0μm to 12.5μm). | LO: Oil LG: Grease LY: Grease or Oil LD: No Lubrication | No Code: Standard (25% ~ 35%) X: 5% ~ 10% L: 10% ~ 15% T: 15% ~ 20% H: 40% ~ 50% J: 50% ~ 60% Note 1: Percentage of the void space within the assembled bearing that is filled with grease. Note 2: Some miniature ball bearings need amount adjustment. |
