Engineering Reference
Miniature & Instrument Ball Bearings
Cages (Retainers and Separators)
The cage is the ball bearing component that separates and positions the balls at equal intervals around the bearing's raceway. This component is also called the retainer or separator. When selecting the most appropriate cage for your application, some factors to consider are bearing rotational speed (rpm), starting and running torque limitations, operating temperature range, and noise limitations. In some cases, such as in high-load applications, a full complement design may be the best choice. NHBB can also supply specially designed cages to meet your specific requirements. Please contact NHBB for assistance with optimum cage selection.
Tables of Cages and Separators
The tables and descriptions provided below are a starting point for selecting the appropriate retainer design for most applications. The two standard cage designs are the ribbon, two-piece stamped and crimped (AISI 300 series CRES), and the crown, one-piece stamped (AISI 400 series CRES). In addition to these standard cages, NHBB offers many other retainer designs to meet specific requirements, including precision-machined retainers for ultra-high-speed applications.
Cages
| Description | P/N Code | Material | Max. Speed (Ref.) dN** | Max. Operating Temp.* | Comments | Typical Applications |
|---|---|---|---|---|---|---|
| Ribbon Two-piece stamped, crimped | R | AISI 305 Steel | 150,000 | 900 °F | Superior starting torque, low cost | General purpose |
| Crown One-piece stamped | H | AISI 410 Steel | 150,000 | 900 °F | Higher speed capability than ribbon retainer, low cost | General purpose |
| Crown One-piece machined | KB KC | Phenolic-paper base Phenolic-linen base | 1,200,000 | 250 °F | High speed capability Porous material Vacuum impregnated with oil | Medical |
| Crown One-piece machined | M5 | Polyamide-imide | 1,200,000 | 500 °F | High speed capability Requires lubrication Fully autoclavable | Medical/Dental |
| Crown One-piece machined Silver coated | SC | Patented composite metal-polymer | 1,200,000 | 500 °F | High speed capability Self-lubricating Fully autoclavable | Medical/Dental |
| Full type One-piece machined | KN KM | Phenolic-paper base Phenolic-linen base | 2,000,000 | 250 °F | Ultra-high speed capability Angular contact bearing only Porous material Vacuum impregnated with oil | Machine tool spindles |
| Full type One-piece machined | M4 | Polyamide-imide | 2,000,000 | 500 °F | Ultra-high speed capability Angular contact bearing only Requires lubrication Fully autoclavable | Medical/Dental |
| Full type One-piece machined Silver coated | SF | Patented composite metal-polymer | 2,200,000 | 500 °F | Ultra-high speed capability Angular contact bearing only Requires lubrication Fully autoclavable | Medical/Dental |
| Crown/Full type | T1 | Meldin® PGM | Consult Factory | 500 °F
| Pourous polyamide-imide material Vacuum impregnated with oil Self-lubricating | Low to medium speed Low speed Light load |
Cage Diagrams
R
H
KB / KC
M5
SC
KN / KM
M4
SF
T1 (Meldin® & PGM)
Additional Ball Separator Designs
| Description | P/N Code | Material | Max Speed (Ref.) dN** | Max. Operating Temp.* | Comments | Typical Applications |
|---|---|---|---|---|---|---|
| Toroid | TT | PTFE | 5,000 | 450 °F | Low torque Low speed Angular contact bearing only | Slow rotation |
| Slug | SL | PTFE | 1,000 | 450 °F | Low torque | Gimbal assembly Slow rotation Low speed |
Diagrams of Additional Ball Separators
TT
SL
Table Footnotes
+ Typical Part Number Designation.
* Rings and balls are heat stabilized to 300 °F.
**dN is bore (in millimeters) x rpm.
Additional cage designs and materials available. Please consult with factory.
Standard Cages
Ribbon, Two-Piece, Stamped & Crimped
Ribbon.
Crown, One-Piece, Stamped
The one-piece stamped crown retainer is manufactured from hardened stainless steel and has coined ball pockets, which provide a hard, smooth, low-friction contact surface to the balls. This design is very lightweight, smooth running, cost effective, and readily available. The one-piece stamped crown retainer is also used in radial bearings, but it has a slightly higher speed capability than the stamped ribbon design. For speeds exceeding the capabilities of this retainer, a machined retainer should be considered.
Crown.
Machined Cages
Crown, One-Piece
Crown.
Full Type, One-Piece
This retainer design is best suited for ultra-high speed applications. Its balanced, symmetrical design makes it stable at very high speeds. This retainer, which can only be utilized with angular contact bearings, is manufactured from a variety of materials to meet specific application requirements, including paper and linen-based phenolics and polyamide-imide. Both phenolic materials may be vacuum impregnated with oil, allowing for better lubricity within the ball pockets. The polyamide-imide material is fully autoclavable, making it well suited for many medical and dental applications. Additionally, polyamide-imide contains a small amount of graphite and PTFE, which aids in lubricity properties. Its lubricity may be further enhanced by a patented silver coating.
Full.
Alternative Machined Cage Materials
NHBB manufactures machined cages from the following materials (consult with factory for availability):
- Meldin® 8100/9000
- Delrin®
- PGM
- PEEK
- Patented Composite Metal-Polymer (Silver-coated polyamide-imide)
Molded Cages
In addition to the machined retainers listed, the NHBB Precision Division offers a limited variety of molded retainers. These may have a lower speed capability as compared to machined retainers mainly due to the fact that machined retainers can be held to tighter tolerances for critical dimensions.
Trademarks
Meldin® is a registered trademark of Saint-Gobain Performance Plastics Corporation.
Delrin® is a registered trademark of DuPont.
