HK1312FM bearing: complete specifications & equivalents
The HK1312FM is a ISO 3245 radial bearing sized 13 x 19 x 12 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 13 mm |
| Outer diameter D | 19 mm |
| Width B | 12 mm |
| Seal / shield | open |
| Basic dynamic load rating C | 6.95 kN |
| Basic static load rating C0 | 7.9 kN |
| Fatigue load limit Pu | 0.965 kN |
| Limiting speed (mechanical) | 12000 rpm |
| Mass | 10 g |
| Manufacturer designation | HK1312FM |
| 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 | 0.512 in |
|---|---|
| Outer diameter D | 0.748 in |
| Width B | 0.472 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 3 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) | 10 of 24 |
| Bore above smallest HK-series size | 10 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the HK1312FM model number is decoded
NTN HK1312FM belongs to the HK-series of open-end drawn-cup needle roller bearings (ISO 3245).Fw = 13 mm names the shaft journal that doubles as the inner raceway; around it the drawn cup measures 19 mm outside and 12 mm across. 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. This cup size is common in power-tool intermediate shafts — drills, saws, grinders — where the gearbox casing is magnesium or aluminium and the cup is pressed into a steel insert. If the shaft sees axial float, allow for it in the housing width — the cup cannot guide the shaft axially, and a shaft that walks will eventually hammer the open end of the shell.
Typical equipment & failure modes
Common applications
- power tool gear reduction stages
- small hydraulic pump drives
- automotive accessory drives
- continuous high-speed rotation where grease redistribution is the limiting factor
Known failure patterns
- cup cracking from an oval or tapered housing bore distorting the thin shell
- fretting of the cup outer surface in a soft or worn housing seat
- scoring of the needle rollers from abrasive contamination past the open ends
Selection pitfalls — read before you substitute
- HK1312FM runs directly on the shaft: the 13 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 HK1312FM 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, HK1312FM reads the 13 mm shaft surface as its raceway: hardness 58–64 HRC and a ground finish are prerequisites, not recommendations.
- The cage in HK1312FM 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 13 mm.
- The 12 mm standard width of HK1312FM is the general-purpose section at 13 mm shaft; wider HK variants in the same 13×19 mm envelope carry more load and are not interchangeable if the housing width is fixed.
Frequently asked questions
Does HK1312FM need a hardened shaft?
Either the 13 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 (IR10x13x12.5) so a standard unhardened shaft can be used.
What duty conditions suit a HK1312FM drawn-cup bearing?
HK1312FM is typically specified for intermittent duty with long standstill periods that invite false brinelling; match the grease/oil speed limits (12000/18000 rpm) and radial load against the actual duty before finalizing.
What are the dimensions of a HK1312FM needle roller bearing?
A HK1312FM drawn-cup needle roller bearing has a 13 mm shaft diameter (Fw, under-roller diameter), 19 mm outside diameter and 12 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 HK1312FM drawn-cup bearing?
Fw is the under-roller diameter — the diameter of the shaft journal on which the needle rollers run directly. For HK1312FM, Fw = 13 mm, so the shaft must be machined to 13 mm, hardened to 58–64 HRC and ground, unless a separate IR inner ring is fitted.
Can a HK1312FM needle roller bearing carry axial load?
No. Drawn-cup needle roller bearings like HK1312FM 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.