HK1210FM bearing: complete specifications & equivalents
The HK1210FM is a ISO 3245 radial bearing sized 12 x 16 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 | 12 mm |
| Outer diameter D | 16 mm |
| Width B | 10 mm |
| Seal / shield | open |
| Basic dynamic load rating C | 5.05 kN |
| Basic static load rating C0 | 6.25 kN |
| Fatigue load limit Pu | 0.76 kN |
| Limiting speed (mechanical) | 13000 rpm |
| Mass | 5 g |
| Manufacturer designation | HK1210FM |
| 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 | 0.472 in |
|---|---|
| Outer diameter D | 0.63 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) | 9 of 24 |
| Bore above smallest HK-series size | 9 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the HK1210FM model number is decoded
As an open-end drawn-cup needle roller bearing in the HK-series (ISO 3245), NTN HK1210FM is built around a thin hardened steel cup.Its printed envelope — 12 mm under-roller diameter, 16 mm outside diameter, 10 mm width — is fixed by ISO 3245; the 12 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. This is the classic two-wheeler and small-engine size class: the cup replaces a bulky machined bearing and lets the gearbox casing shrink around it. Industrial sewing machines and textile equipment run this size on their shuttle and needle-bar drive shafts, where the compact radial section keeps the arm profile slim. Shaft tolerance for this size is h5 or j5: the roller complement needs a controlled radial clearance, and a shaft ground to general-purpose tolerances can leave the bearing either slack or pinched.
Typical equipment & failure modes
Common applications
- two-stroke engine crank and piston pins
- power tool gear reduction stages
- small hydraulic pump drives
- heavily loaded slow pivots where static rating, not dynamic life, governs the choice
Known failure patterns
- scoring of the needle rollers from abrasive contamination past the open ends
- brinelling of the drawn cup from hammer blows during press-in mounting
- grease starvation in the open-end arrangement with no relubrication path
Selection pitfalls — read before you substitute
- HK1210FM runs directly on the shaft: the 12 mm shaft journal must be hardened to 58–64 HRC and ground to Ra ≤ 0.2 µm, or fit the matching IR inner ring instead.
- The open ends of HK1210FM retain no lubricant: grease must be supplied by the housing arrangement, and adjacent seals are needed in dirty or washdown duty.
- With no inner ring, HK1210FM reads the 12 mm shaft surface as its raceway: hardness 58–64 HRC and a ground finish are prerequisites, not recommendations.
- The cage in HK1210FM 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 12 mm.
- The 10 mm narrow section of HK1210FM is the compact option at 12 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 12×16 mm envelope.
Frequently asked questions
Does HK1210FM need a hardened shaft?
Either the 12 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 (IR8x12x10.5) so a standard unhardened shaft can be used.
What duty conditions suit a HK1210FM drawn-cup bearing?
HK1210FM is typically specified for reciprocating or oscillating motion where the rollers never complete a full revolution; match the grease/oil speed limits (13000/20000 rpm) and radial load against the actual duty before finalizing.
What are the dimensions of a HK1210FM needle roller bearing?
A HK1210FM drawn-cup needle roller bearing has a 12 mm shaft diameter (Fw, under-roller diameter), 16 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 HK1210FM drawn-cup bearing?
Fw is the under-roller diameter — the diameter of the shaft journal on which the needle rollers run directly. For HK1210FM, Fw = 12 mm, so the shaft must be machined to 12 mm, hardened to 58–64 HRC and ground, unless a separate IR inner ring is fitted.
Can a HK1210FM needle roller bearing carry axial load?
No. Drawn-cup needle roller bearings like HK1210FM 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.