HK0810FM bearing: complete specifications & equivalents
The HK0810FM is a ISO 3245 radial bearing sized 8 x 12 x 10 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 8 mm |
| Outer diameter D | 12 mm |
| Width B | 10 mm |
| Seal / shield | open |
| Basic dynamic load rating C | 3.85 kN |
| Basic static load rating C0 | 3.95 kN |
| Fatigue load limit Pu | 0.48 kN |
| Limiting speed (mechanical) | 20000 rpm |
| Mass | 3 g |
| Manufacturer designation | HK0810FM |
| Standard | ISO 3245 |
| Catalog version | CAT. No. 2203-3/E 2024 |
| Last verified | 2026-09-25 |
Source: catalog reference (CAT. No. 2203-3/E 2024) · extracted 2026-09-25
Parameters extracted from the official NTN Ball and Roller Bearings catalogue (CAT. No. 2203-3/E 2024); NTN® is a trademark of NTN Corporation, used here for identification only — mpnbase is not an authorized NTN distributor. Boundary dimensions are ISO 15 interchangeable; current production values may differ, verify at ntnglobal.com.
Dimensions in inches & HK-series range
| Bore d | 0.315 in |
|---|---|
| Outer diameter D | 0.472 in |
| Width B | 0.394 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 2 mm |
| Smallest bore in HK-series | 3 mm |
| Largest outer diameter in HK-series | 58 mm |
| Width range across HK-series | 6–38 mm |
| Bore position in HK-series (smallest first) | 6 of 24 |
| Bore above smallest HK-series size | 5 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the HK0810FM model number is decoded
As an open-end drawn-cup needle roller bearing in the HK-series (ISO 3245), NTN HK0810FM is built around a thin hardened steel cup.Its printed envelope — 8 mm under-roller diameter, 12 mm outside diameter, 10 mm width — is fixed by ISO 3245; the 8 mm figure is the shaft journal itself, which carries the rollers directly. There is no separate inner ring — the thin-walled cup is drawn from sheet steel, hardened, and press-fitted into the housing, giving the smallest radial section of any rolling bearing at this shaft size. The FM/FT2 suffix marks NTN's caged drawn-cup execution: a formed steel cage keeps the rollers evenly spaced, lowering friction and noise versus full-complement drawn cups. In this size range the drawn cup gives a far smaller radial section than any machined-ring needle bearing of the same shaft, which is why it dominates in compact transmissions. Conveyor and packaging-machinery builders choose this size for idler and tensioner rollers: the open ends accept a grease fill at assembly and the cup survives the life of the roller shell. When the housing is aluminium or magnesium, press this cup into a steel insert rather than the bare casting — differential thermal expansion will walk the cup out of a soft bore at operating temperature.
Typical equipment & failure modes
Common applications
- lawn and garden equipment spindles
- motorcycle and scooter transmissions
- two-stroke engine crank and piston pins
- compact linkages where the cup doubles as both bearing and structural spacer
Known failure patterns
- grease starvation in the open-end arrangement with no relubrication path
- raceway spalling on a shaft that was below the required 58–64 HRC hardness
- edge loading and needle skewing under shaft misalignment or deflection
Selection pitfalls — read before you substitute
- Needle rollers tolerate almost no misalignment; if the 12 mm housing seat cannot be held square to the shaft, expect edge loading and early spalling.
- Press the drawn cup in with a mandrel bearing on the stamped face only — never hammer the cup or press through the rollers, that cracks or brinells the shell.
- At a 8 mm shaft diameter, shaft surface finish is critical for HK0810FM: grinding marks, corrosion pits or chrome flaking on the journal will fluke the rollers within hours — polish or replace a suspect shaft.
- The cage in HK0810FM spaces the rollers but is not a seal: it retains nothing against dust or washdown, so the housing still needs its own sealing arrangement at 8 mm.
- The 10 mm narrow section of HK0810FM is the compact option at 8 mm shaft: load capacity is limited by the short roller length, so verify the required rating before choosing it over a wider HK variant in the same 8×12 mm envelope.
Frequently asked questions
Does HK0810FM need a hardened shaft?
Either the 8 mm shaft journal must be hardened to 58–64 HRC and ground to Ra ≤ 0.2 µm, or you can fit the matching inner ring (IR5x8x12) so a standard unhardened shaft can be used.
What duty conditions suit a HK0810FM drawn-cup bearing?
HK0810FM is typically specified for lightly loaded high-speed idler positions where roller skidding must be watched; match the grease/oil speed limits (20000/30000 rpm) and radial load against the actual duty before finalizing.
What are the dimensions of a HK0810FM needle roller bearing?
A HK0810FM drawn-cup needle roller bearing has a 8 mm shaft diameter (Fw, under-roller diameter), 12 mm outside diameter and 10 mm width, per ISO 3245 boundary dimensions. It has no inner ring — the shaft journal serves as the raceway.
What does Fw mean on a HK0810FM drawn-cup bearing?
Fw is the under-roller diameter — the diameter of the shaft journal on which the needle rollers run directly. For HK0810FM, Fw = 8 mm, so the shaft must be machined to 8 mm, hardened to 58–64 HRC and ground, unless a separate IR inner ring is fitted.
Can a HK0810FM needle roller bearing carry axial load?
No. Drawn-cup needle roller bearings like HK0810FM carry radial load only and provide no axial shaft location. Axial forces must be carried by separate thrust washers or a locating bearing in the arrangement.
Reviewed & verified by the MPN Base engineering desk against source catalog CAT. No. 2203-3/E 2024 on 2026-09-25. Read our editorial & correction policy.