Fafnir2MM210WICRTUHSuper Precision Angular Contact Ball Bearing – Triplex Universal Set, 50 mm ID, 90 mm OD, 20 mm Width, 15 Degree Contact Angle, Heavy Preload, P4S

Product Description

What this part is

Fafnir 2MM210WICR-TUH super-precision angular contact ball bearing, supplied as a triplex universal set of three bearings. Bore 50 mm, outside diameter 90 mm, width 20 mm per bearing, giving 60 mm across the assembled stack. Open on both faces, with a phenolic outer-land-riding cage and steel balls on chrome steel races.

Decoding the designation

The leading 2MM sets a 15° contact angle. The MM prefix marks the Fafnir super-precision spindle range and carries P4S accuracy, equivalent to ABEC 7 running accuracy with ABEC 9 geometry on the critical surfaces. 210 is the bore code within the 200WI series, which follows the ISO 7200 light dimension series, so this bearing is dimensionally a 7210. CR denotes the phenolic cage riding on the outer ring land. TUH is a triplex universally ground set at heavy preload.

What these specs mean in practice

A 15° contact angle favours speed and radial stiffness over thrust capacity; a 25° bearing of the same envelope would carry more axial load and turn more slowly. The phenolic outer-land-riding cage is light and tolerant of marginal lubrication, which is why it is standard on high-speed machine tool spindles. Heavy preload maximises axial and radial stiffness and holds running accuracy under cutting load, at the cost of higher running heat and a lower speed ceiling than a light-preload set.

Quantity and configuration

Three bearings, matched and universally ground as one triplex set at heavy preload. Universal grinding means the three rings can be stacked back-to-back, face-to-face or in tandem and the built-in preload is established by clamping the rings together, with no spacers or shims required.

Fitting notes

The three bearings are ground as a matched group and are installed together in the order and orientation marked on the outer ring faces. A preloaded set is clamped solid against its shoulders; no internal clearance is set at assembly.

Interchange guidance

Matching 15° phenolic-cage triplex sets at heavy preload: FAG B7210-C-T-P4S-TUH and RHP 7210CTTUHP4. A 3MM210WI bearing has the same 50 x 90 x 20 mm size but a 25° contact angle, so it carries more thrust at a lower speed and is not a drop-in.