RHP7018CTDUMP2Super-Precision Angular Contact Ball Bearing – Straight Bore, 90 mm ID, 140 mm OD, 24 mm Width, Open, 15° Contact Angle, Phenolic Cage, Medium Preload, Duplex Ground, ABEC 9

Product Description

What this part is

RHP 7018CTDUMP2 super-precision single-row angular contact ball bearing, 90 mm bore, 140 mm outside diameter, 24 mm width. Steel balls, phenolic cage, open on both faces, straight bore, duplex ground to the medium preload class.

Decoding the designation

70 is the ISO light dimension series and 18 is the bore code — 18 × 5 = 90 mm. In the RHP scheme the C is a 15° contact angle, the T is a phenolic cage, DU marks duplex grinding, M calls medium preload, and P2 is the tolerance class, equal to ABEC 9. The carton’s alternate designation B7018X2TADULEP9 reads the same bearing in RHP’s B-series codes, where X2 is again 15° and EP9 is again ABEC 9, so angle and class are cross-confirmed by two independent markings.

What these specs mean in practice

ABEC 9 is the tightest tolerance class in general commercial use, held for grinding spindles and high-accuracy rotary tables where runout drives the finished part. The 15° contact angle biases the bearing toward speed and radial rigidity; the same envelope at 25° carries more thrust and turns slower. Medium preload buys stiffness over the light class at the cost of some heat generation. The phenolic cage is rated to 120 °C.

Thrust direction and arrangement

Each row of angular contact balls takes thrust in one direction, toward the high shoulder of the outer ring. Duplex grinding means the mating faces are relieved so that a set clamps up to the ground preload with no shims. A back-to-back or face-to-face set locates the shaft in both directions and resists moment loads; a tandem set stays one direction and shares the thrust.

Quantity and configuration

Duplex-ground DUM set designation, medium preload class, no spacers.

Fitting notes

The face marks establish which arrangement the ground relief produces, so a duplex set stays together and keeps its marked orientation. Interference on the shaft and housing seats adds to the ground preload, so at ABEC 9 the seats are ground and measured rather than cut to nominal 90 mm and 140 mm.

Interchange guidance

The same-spec 15° duplex-medium designations at this envelope and class are the FAG B7018-C-T-P2S-DUM, the SKF 7018 CD/P2ADGB and the Timken Fafnir 2MMV9118WI CR DUM. The NSK 7018CTYNDUMP2 matches on angle, arrangement and class but carries a polyamide cage instead of phenolic, so it is a related designation. A 7018 in the P4 class or at 25° is a related size rather than a substitution.