Fafnir2MM9121WI DULSuper-Precision Angular Contact Bearing Matched Pair 105x160x26 mm 15° Light Preload Phenolic Cage ABEC 7/9

Product Description

What this part is:

A Fafnir 2MM9121WI-CR-DUL matched duplex pair of super-precision single-row angular contact ball bearings. Each bearing is 105 mm bore, 160 mm outside diameter, 26 mm wide, giving 52 mm total stack width. Open on both faces, universally ground as a set.

Decoding the designation:

• 2MM — 15° contact angle in the Fafnir scheme; the MM prefix carries the P4S build
• 9121 — leading 9 marks the ISO 70 light series, 105 mm bore, so the ISO equivalent is 7021-C
• WI — super-precision spindle bearing series
• CR — phenolic outer-land-riding cage
• DU — duplex, ground as a matched set
• L — light preload

What these specs mean in practice:

An outer-land-riding phenolic cage is guided on the outer ring rather than the balls, which keeps cage motion stable at high speed and holds oil in the pocket faces. The 15° angle favours speed and radial stiffness; light preload gives the lowest running temperature of the three grades.

Published specifications:

• Bore: 105 mm
• Outside diameter: 160 mm
• Width: 26 mm per bearing, 52 mm stacked
• Contact angle: 15°
• Precision: P4S — ABEC 7 / ABEC 9
• Preload: light, factory matched
• Cage: phenolic, outer-land riding
• Rows: 1 per bearing
• Closure: open

Quantity and configuration:

Matched duplex pair. 2 Pcs per sale unit.

Fitting notes:

Each bearing carries thrust in one direction; the pair mounted back-to-back or face-to-face covers both. The etched marks on the outer rings align to hold the matched offset as ground.

Interchange guidance:

Same-spec matched pairs at 15°, super precision, light preload: RHP 7021CTDULP4, FAG B7021C.T.P4S.UL, SKF 7021 CD/P4ADGA, NSK 7021CTRDULP4, SNR 7021CG1DUJ74. The 25° 3MM9121WI is a related size rather than an interchange.