How to Read High-Speed Dental Handpiece Bearing Codes
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A bearing should not be selected by appearance alone. Parts with the same outside diameter may differ in ring width, shield arrangement, cage construction, ball material or contact geometry. These details must be checked before a replacement is ordered.
Identification summary
Record the bearing code, then measure the inner diameter, outer diameter and width. Check the cage, shield, flange or groove, and ball material. Supplier suffixes are not universal, so the dimensions and construction listed on the individual product page remain the final reference.
Measurement comes first
Measure the removed bearing as ID × OD × W. If the inner and outer rings have different widths, record both values. Take clear front and side photographs before cleaning or discarding the old bearing. A side view often reveals a flange, groove, shield or stepped outer ring that is not obvious from the front.
Code reference used in this catalog
The table below describes the supplier convention used for the high-speed bearings listed by Handpiece Parts Hub. It should not be treated as a universal bearing standard.
| Code | Catalog reference |
|---|---|
| R144, R133 and similar | Basic bearing series. Confirm the dimensions shown on the product page. |
| F | Outer-ring flange or thrust edge. |
| K1 / K2 | Angular-contact construction. K1 identifies a separable inner ring; K2 identifies a separable outer ring. |
| TA / TL / Ti | Cage variants. TL commonly identifies a black polyimide cage, TA a yellow polyimide cage, and Ti a fabric-reinforced phenolic cage in this catalog. |
| K / G | Stepped or grooved outer-ring form. |
| Z / Z1 | One-sided shield variants. |
| W / W02 | Ring-width variants. W commonly indicates 2.78 mm for both rings. W02 commonly indicates a 2.38 mm outer ring and 2.78 mm inner ring. Verify the listed dimensions. |
| N | Si3N4 ceramic balls. A code without N commonly uses 440C stainless-steel balls in this catalog. |
| S | Supplier or material-series prefix. The Material field on the product page takes priority. |
Example: SR144TLZN
Under this catalog convention, R144 is the basic series, TL identifies the cage variant, Z identifies a shield detail, and N indicates ceramic balls. The code alone does not confirm fitment. Dimensions and construction must also match. For reference, HP-HS-A1 is listed as 3.175 × 6.35 × 2.38 mm.
Technical references
- NSK Air Turbine Bearings — official application and operating reference for dental air-turbine bearings.
- NSK Formulation of Bearing Designations — official designation examples covering bearing width, materials, shields, tolerance and lubrication codes.