Fafnir3MM9124WIDUHSuper-Precision Angular Contact Bearing Matched Pair 120x180x28 mm 25° Heavy Preload Phenolic Cage ABEC 7/9

Product Description

What this part is

A Fafnir 3MM9124WI-CR-DUH matched duplex pair of super-precision single-row angular contact ball bearings. Each bearing is 120 mm bore, 180 mm outside diameter, 28 mm wide, giving 56 mm total stack width. Open on both faces, universally ground as a set.

Decoding the designation

3MM — 25° contact angle in the Fafnir scheme; the MM prefix carries the P4S build9124 — leading 9 marks the ISO 70 light series, 120 mm bore, so the ISO envelope is the 7024 sizeWI — super-precision spindle bearing seriesCR — phenolic outer-land-riding cageDU — duplex, ground as a matched setH — heavy preload

What these specs mean in practice

A 25° contact angle carries more thrust and less speed than a 15° of the same envelope. Combined with heavy preload it gives the stiffest axial behaviour available in this size, which suits spindles taking large axial cutting loads. The outer-land-riding phenolic cage keeps cage motion stable at speed.

Published specifications

Bore: 120 mmOutside diameter: 180 mmWidth: 28 mm per bearing, 56 mm stackedContact angle: 25°Precision: P4S — ABEC 7 / ABEC 9Preload: heavy, factory matchedCage: phenolic, outer-land ridingRows: 1 per bearingClosure: 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 25°, super precision, heavy preload: RHP 7024ETDUHP4, FAG B7024E.T.P4S.UH, SKF 7024 ACD/P4ADGC, NSK 7024A5TRDUHP4. The 15° 2MM9124WI shares the envelope and is a related size rather than an interchange.