HK0509FM bearing: complete specifications & equivalents
The HK0509FM is a ISO 3245 radial bearing sized 5 x 9 x 9 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 5 mm |
| Outer diameter D | 9 mm |
| Width B | 9 mm |
| Seal / shield | open |
| Basic dynamic load rating C | 2.45 kN |
| Basic static load rating C0 | 1.99 kN |
| Fatigue load limit Pu | 0.243 kN |
| Limiting speed (mechanical) | 27000 rpm |
| Mass | 2 g |
| Manufacturer designation | HK0509FM |
| 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 | 0.197 in |
|---|---|
| Outer diameter D | 0.354 in |
| Width B | 0.354 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) | 3 of 24 |
| Bore above smallest HK-series size | 2 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the HK0509FM model number is decoded
HK0509FM is an NTN drawn-cup needle roller bearing with open ends in the HK-series (ISO 3245 boundary dimensions).The designation encodes the shaft fit directly: Fw = 5 mm is the under-roller diameter, i.e. the shaft journal that serves as the inner raceway; the cup outside diameter is 9 mm and the width is 9 mm. 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. At this miniature shaft size the cup wall is fractions of a millimetre thick, so handling cleanliness and housing-bore accuracy matter more than the paper load rating. 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
- office machine and printer mechanisms
- small appliance gear drives
- instrument and meter linkages
- 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
- At a 5 mm shaft diameter the cup wall of HK0509FM is extremely thin; inspect for transportation dents before pressing in, and deburr the housing bore edge or the cup will score and split on entry.
- The cage in HK0509FM 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 5 mm.
- The 9 mm narrow section of HK0509FM is the compact option at 5 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 5×9 mm envelope.
- HK0509FM runs directly on the shaft: the 5 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 HK0509FM retain no lubricant: grease must be supplied by the housing arrangement, and adjacent seals are needed in dirty or washdown duty.
Frequently asked questions
What are the dimensions of a HK0509FM needle roller bearing?
A HK0509FM drawn-cup needle roller bearing has a 5 mm shaft diameter (Fw, under-roller diameter), 9 mm outside diameter and 9 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 HK0509FM drawn-cup bearing?
Fw is the under-roller diameter — the diameter of the shaft journal on which the needle rollers run directly. For HK0509FM, Fw = 5 mm, so the shaft must be machined to 5 mm, hardened to 58–64 HRC and ground, unless a separate IR inner ring is fitted.
Can a HK0509FM needle roller bearing carry axial load?
No. Drawn-cup needle roller bearings like HK0509FM 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.
How is a HK0509FM retained in the housing?
The thin-walled drawn cup of HK0509FM is press-fitted into a 9 mm housing bore (typically N6/N7 tolerance for steel housings). The press fit alone retains the cup — no snap rings or shoulders are needed, but the bore must be round and rigid.
What duty conditions suit a HK0509FM drawn-cup bearing?
HK0509FM is typically specified for reciprocating or oscillating motion where the rollers never complete a full revolution; match the grease/oil speed limits (27000/40000 rpm) and radial load against the actual duty before finalizing.
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.