RHPSuper-Precision Angular Contact Ball Bearing 40 x 80 x 18 mm, ABEC 7, Universal Duplex, Light Preload, Phenolic Cage

Product Description

What this part is

A single super-precision angular contact ball bearing in the ISO 7208 envelope: 40 mm bore, 80 mm outside diameter, 18 mm width. It is ground to ABEC 7 and universally ground, meaning two of them can be stacked face-to-face, back-to-back or in tandem without shims or measuring, and will settle at a repeatable light preload on their own. This is spindle-grade hardware, not a general-purpose ball bearing.

Decoding the designation

B — RHP super-precision spindle bearing prefix.

7208 — ISO angular contact base number, 40x80x18 mm, light 72xx series.

X2 — RHP design variant covering the internal geometry and contact angle of the X2 specification.

TA — phenolic (laminated fabric) cage.

DUL — duplex, universally ground, light preload.

EP7 — RHP precision grade corresponding to ABEC 7.

What these specs mean in practice

The phenolic cage is the reason this bearing tolerates speed. Laminated fabric is far lighter than steel or brass, so cage inertia and ball pocket friction stay low, and phenolic absorbs oil, which helps it survive marginal lubrication at start-up. The trade-off is temperature: phenolic is not a high-temperature material, so sustained running much above roughly 120 °C will degrade it.

Light preload is the setting for applications where speed and heat matter more than absolute stiffness. Heavier preload buys rigidity but generates more heat and shortens life at high speed. Preload is built into the ground faces of a universally ground bearing, so it cannot be dialled in later, and preload classes must not be mixed across a pair.

Published ratings

Dynamic load rating 36.5 kN. Static load rating 24.1 kN. Limiting speed 19000 rpm. Contact angle 15°. Temperature range -30 °C to 120 °C. Mass 0.81 lbs.

Mounting data

Boundary dimensions 40 x 80 x 18 mm, straight bore, open. Universal grind permits back-to-back (DB), face-to-face (DF) or tandem (DT) pairing without calculated spacers or shims.

Quantity and configuration

One bearing is supplied. DUL describes how two of these behave once mounted together as a set; it does not mean two are in the box. A duplex pair requires two units, taken from the same lot so the ground faces match.

Interchange guidance

RHP is now part of NSK, so current-production equivalents carry NSK designations. Same-envelope super-precision alternatives from other makers include 7208 C and 7208 A5 type numbers at 40x80x18 mm, but confirm contact angle, cage material and preload class before substituting; matching only the boundary dimensions is not enough on a spindle bearing.