Barden2115HDMSuper Precision Angular Contact Ball Bearing 75x115x20 mm, Duplexable, Medium Preload — ONE Bearing (Half of a Pair)

Product Description

What this part is

A Barden 2115HD super-precision angular contact ball bearing, 75 mm bore x 115 mm outside diameter x 20 mm wide — the 7015 spindle envelope. Barden built precision and super-precision bearings for machine tool spindles, instruments and aerospace, and the HD range is ground so that two bearings clamp up into a defined duplex preload.

Decoding the designation

2115 – Barden angular contact series number; the 115 size code corresponds to the 7015 envelope, 75 x 115 x 20 mm.
HD – duplexable: the ring faces are ground flush to a controlled offset so two bearings can be mounted back-to-back, face-to-face or in tandem and arrive at a repeatable preload.
M – medium preload.
-1/2PR – half of a pair. This is the detail that matters most on this listing: it means one bearing, not a set of two.

What these specs mean in practice

Duplexing is what turns two angular contact bearings into a stiff, play-free spindle bearing arrangement. Because the faces are ground to a known offset, clamping the pair produces a defined preload with no shimming and no measurement at the bench — and that preload only exists when the pair is complete and fully clamped.

Medium preload sits between light and heavy. Against light preload it gives more axial and radial stiffness, so the spindle deflects less under cutting load and holds size better; against heavy preload it runs cooler and draws less power. It is the usual choice for a general-purpose machine tool spindle that has to be both accurate and reasonably fast. Note that preload class is not interchangeable: mixing an M bearing with an L or H bearing gives you neither preload and defeats the point of buying ground faces.

Published dimensions

Bore (d): 75 mm
Outside diameter (D): 115 mm
Width (B): 20 mm
Rows: 1
Preload: medium (M)
Arrangement: HD, duplexable, universally ground
Closure: open, no seals or shields

Quantity and configuration

This listing is one bearing — half of a duplex pair, which is exactly what the -1/2PR suffix means. It is a complete, usable bearing on its own, but it will not develop a duplex preload without a matching partner of the same designation and preload class. If you need the full pair, ask us before ordering: orphaned halves of the same designation are frequently on adjacent shelves here and can be supplied as a matched pair.

Fitting notes

Orient the high shoulder towards the thrust load. Press or heat onto the shaft against the inner ring only — never hammer a super-precision bearing. Clamp the rings fully; a partially clamped duplexable bearing never develops its designed preload. Grease sparingly, roughly a quarter to a third fill, or run the oil-air system the spindle was designed around. A single angular contact bearing locates the shaft in one direction only and needs an opposing bearing in the arrangement.

Interchange guidance

Barden is part of Schaeffler (FAG), so Schaeffler Barden numbers are the current lineage. Same-envelope 75 x 115 x 20 mm super-precision equivalents, with the contact angle each one names: FAG B7015-C-T-P4S-UM at 15° and B7015-E-T-P4S-UM at 25°, NSK 7015CTYNSUMP4 at 15° and 7015A5TYNSUMP4 at 25°, SKF 7015 CD/P4A at 15° and 7015 ACD/P4A at 25°, Fafnir/Timken 2MM215WICR at 15° and 3MM215WICR at 25°, RHP 7015CTSUMP4 at 15°. All of these fit the same bore and housing, so they are dimensionally correct cross-references — match the contact angle and the medium preload class your spindle was built around. The 7115-C reading that has travelled with this record is a transcription of 7015C; the corrected ISO form is 7015 and that is what buyers should search.