NKIS15-XL bearing: complete specifications & equivalents

Specification table

Source: catalog reference (HR1 2026-09-25) · extracted 2026-09-30

Parameters extracted from the official FAG Rolling Bearings catalogue (HR1 2026-09-25); FAG® is a trademark of Schaeffler Technologies AG & Co. KG, used here for identification only — mpnbase is not an authorized FAG/Schaeffler distributor. Boundary dimensions are ISO 15 interchangeable; current production values may differ, verify at schaeffler.com.

Cross references & equivalents

Interchange levels: full standard interchange · partial verify parameters · verify manual confirmation required. Links resolve to the equivalent model's specification page where available.

How the NKIS15-XL model number is decoded

envelope 15×35×20 mm: 15 mm bore accepts a normal-tolerance machined shaft via the integral inner ring, with a thin 10.0 mm radial section packed with small-diameter needle rollers C is 27.5 kN and C0 28 kN at the 15 mm seat; the C/C0 ratio of 0.98 is characteristic of a needle bearing — high static rating relative to dynamic in a compact 35 mm outside diameter the fatigue load limit Cur is 5 kN, the limiting speed 18,500 r/min and the thermal reference speed 9,400 r/min; for small needle bearings the reference speed can exceed the kinematic limit, so the lower of the two governs the application dynamic capacity per millimetre of bore is 1.83 kN/mm and per millimetre of width 1.38 kN/mm — the reason 20 mm-wide needle bearings routinely replace much larger ball or roller positions mass is 92 g, just 0.13 g per mm² of projected 35×20 mm envelope, which keeps unbalanced forces low in fast-actuating linkages with a 15 mm bore the 20 mm width and 27.5 kN C rating suit high-cycle industrial machinery rather than instrument duty NKIS15-XL is supplied with a machined inner ring, so it mounts on an ordinary turned and ground shaft of normal tolerance — hardening the journal is not required This is the choice for OEM production on soft shafts: machine the 15 mm seat to the recommended tolerance, fit the bearing, and let the inner ring provide the precision raceway The -XL suffix is the Schaeffler X-life mark: interchangeable envelope with the basic bearing, but higher load capacity and lower running temperature at the 18,500 r/min limit. Typical applications include rocker arms and valve trains, two-stroke and compressor piston pins and small electric motor accessory drives, where the 35 mm outside diameter and 27.5 kN dynamic rating match the duty. In rocker arms and valve trains the unit fits a compact 15 mm seat, and in two-stroke and compressor piston pins the 92 g mass keeps unbalanced forces low in fast linkages. Designers also specify it for small electric motor accessory drives, relying on the 20 mm width and the published 28 kN static rating. Keep the specified radial clearance; an oversized shaft or heavy interference removes it and the needles bind hot immediately. Without an inner ring the shaft is the raceway: 58–64 HRC and a ground, polished journal are mandatory, not recommendations.

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• Keep the specified radial clearance; an oversized shaft or heavy interference removes it and the needles bind hot immediately.
• Without an inner ring the shaft is the raceway: 58–64 HRC and a ground, polished journal are mandatory, not recommendations.
• Open ends draw contamination directly onto the needles; specify sealed or shielded positions in dusty environments rather than relying on grease alone.