SNFASuper Precision Angular Contact Ball Bearing 12x28x8 mm 15° ABEC 9 Duplex Universal Medium Preload Matched Pair

Product Description

What this part is

An SNFA VX12-9CE1DUM super-precision angular contact ball bearing in the 12 x 28 x 8 mm envelope, supplied as a matched duplex universal pair. That envelope is the ISO 7001 size, which is why the listing carries a 7001-C-P2 cross alongside the SNFA designation.

Decoding the designation

VX identifies the SNFA super-precision angular contact spindle bearing series. 12 is the 12 mm bore. 9 denotes ABEC 9 precision. CE1 denotes a 15° contact angle in the SNFA scheme. DU denotes duplex universal grinding, so the pair mounts back-to-back, face-to-face or in tandem. M denotes medium preload.

What these specs mean in practice

A 15° contact angle favours speed and radial stiffness over thrust capacity, the reverse of a 25° bearing in the same envelope, which is why this angle dominates high-speed grinding and small milling spindles. Medium preload sits between light and heavy: more axial stiffness and better running accuracy than light preload, with a higher equilibrium temperature and a lower speed ceiling. ABEC 9 is the tightest class in general super-precision production, controlling bore, outside diameter and raceway runout to the levels a high-speed spindle needs to stay in balance.

Published specifications

Bore: 12 mm (0.4724 in). Outside diameter: 28 mm (1.1024 in). Width per bearing: 8 mm (0.3150 in). Total width of the pair: 16 mm (0.6299 in). Contact angle: 15°. Precision class: ABEC 9. Rows: single row per bearing. Closure: open. ISO envelope equivalent: 7001.

Quantity and configuration

2 Pcs, a duplex universal matched pair at medium preload. Universal grinding means the two bearings deliver the intended preload in any of the three standard arrangements when mounted as a pair.

Fitting notes

The bearings mount with the marked faces adjacent for a back-to-back or face-to-face set, on a ground shaft seat and into a ground housing bore held to the ABEC 9 class. The pair stays together in handling, since the preload comes from the matched grinding of the two rings rather than from any adjustment at assembly.

Interchange guidance

Genuine equivalents are 15°, P4 or better, duplex universal medium-preload pairs in the 7001 envelope — SKF 7001 CD/P4ADGB, FAG B7001-C-T-P4S-UM and NSK 7001CTRDUMP4 fall in that group. A 25° bearing in the same envelope (7001 AC, SNFA CE2 variants), a light or heavy preload grade (DUL, DUH) or a lower precision class is a related size rather than an interchange.