Fafnir2MMV9122HXCRSULHybrid Ceramic Super-Precision Angular Contact Ball Bearing – Straight Bore, 110 mm ID, 170 mm OD, 28 mm Width, Open, 15° Contact Angle, Phenolic Cage, Light Preload, 1 Pc

Product Description

What this part is

A Timken Fafnir hybrid ceramic super-precision angular contact ball bearing for machine tool spindle service. Silicon nitride ceramic balls run on bearing steel rings, held in a phenolic cage that rides on the outer ring land. Bore 110 mm, outside diameter 170 mm, width 28 mm. Single row, open on both faces, universally ground to the light preload class, and built to P4S tolerances.

Decoding the designation

2MM sets the contact angle and the class: 2 is a 15° contact angle, and the MM prefix denotes P4S, which is ABEC 7 dimensional accuracy with ABEC 9 running accuracy. 9122 is the size code, and the leading 9 marks the ISO 70 light series, so the envelope is the ISO 7022 size of 110 x 170 x 28 mm. HX identifies the hybrid ceramic build. CR is the phenolic outer-land-riding cage. SUL is a single universally ground bearing in the light preload class.

What these specs mean in practice

Silicon nitride balls weigh about 40 percent of a steel ball of the same size, so centrifugal loading on the outer raceway falls sharply at speed. The result is a higher speed ceiling, less heat generation and lower thermal growth than the all-steel equivalent, along with greater stiffness from the higher ceramic modulus. Ceramic and steel also resist adhesive wear against each other, which extends life under thin-film and oil-mist lubrication. A 15° contact angle favours speed and radial stiffness where a 25° angle favours thrust capacity, and light preload is the setting chosen when maximum speed matters more than maximum rigidity.

Quantity and configuration

One bearing. Universal grinding means it can run alone or be stacked with further SUL bearings of the same number, where the ground offsets develop light preload in back-to-back, face-to-face or tandem arrangements without shims or spacers.

Fitting notes

Shaft and housing seats are prepared to P4S practice, and clamping is applied evenly across the full ring face so the ground offset closes uniformly. Ceramic balls tolerate marginal lubrication better than steel but the phenolic cage sets the upper service temperature for the assembly. Where several SUL bearings are stacked, the ring marks are aligned to the intended arrangement so the offsets add in the right direction.

Interchange guidance

The ISO base number is 7022, and the equivalent hybrid ceramic super-precision builds are SKF 7022 CD/HC/P4A and FAG HCB7022-C-T-P2-UL, both at the same 15° angle. The all-steel Fafnir 2MM9122WI CR SUL shares the envelope, the angle and the preload class but uses steel balls, so it is a related size rather than a substitution. The 3MM9122 build shares the envelope at a 25° angle, which is likewise a different part.