NKI15-20-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 NKI15-20-XL model number is decoded

envelope 15×27×20 mm: 15 mm bore accepts a normal-tolerance machined shaft via the integral inner ring, with a thin 6.0 mm radial section packed with small-diameter needle rollers C is 18.7 kN and C0 23.6 kN at the 15 mm seat; the C/C0 ratio of 0.79 is characteristic of a needle bearing — high static rating relative to dynamic in a compact 27 mm outside diameter the fatigue load limit Cur is 4.2 kN, the limiting speed 21,600 r/min and the thermal reference speed 12,100 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 1.25 kN/mm and per millimetre of width 0.93 kN/mm — the reason 20 mm-wide needle bearings routinely replace much larger ball or roller positions mass is 48.7 g, just 0.09 g per mm² of projected 27×20 mm envelope, which keeps unbalanced forces low in fast-actuating linkages at 15 mm bore this size balances the 27 mm outside diameter against machineability of the adjacent parts — the most frequently specified band in the HR1 range The 6.0 mm section still holds a full needle pack; like all needle bearings it cannot tolerate angular misalignment, so shaft and housing axes must be parallel Reading the NKI prefix: machined-ring needle bearing with inner ring, one roller row, capable of pure radial load at 18.7 kN C X-life status (-XL) indicates the current Schaeffler premium execution at 15 mm bore; the 23.6 kN C0 rating reflects the improved rolling-contact geometry. Typical applications include connecting-rod small ends, textile machine heald and cam shafts and motorcycle and light-vehicle transmissions, where the 27 mm outside diameter and 18.7 kN dynamic rating match the duty. In connecting-rod small ends the unit fits a compact 15 mm seat, and in textile machine heald and cam shafts the 48.7 g mass keeps unbalanced forces low in fast linkages. Designers also specify it for motorcycle and light-vehicle transmissions, relying on the 20 mm width and the published 23.6 kN static rating. Without an inner ring the shaft is the raceway: 58–64 HRC and a ground, polished journal are mandatory, not recommendations. Adding an IR inner ring changes the envelope logic: the same outer assembly then fits a smaller shaft — recheck bore, clearance and ratings when substituting.

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• Without an inner ring the shaft is the raceway: 58–64 HRC and a ground, polished journal are mandatory, not recommendations.
• Adding an IR inner ring changes the envelope logic: the same outer assembly then fits a smaller shaft — recheck bore, clearance and ratings when substituting.
• Keep the specified radial clearance; an oversized shaft or heavy interference removes it and the needles bind hot immediately.