RHPB7016X2TADUMEP7Super Precision Angular Contact Ball Bearing Set 80x125x22 mm, 30° Contact Angle, Phenolic Cage, EP7 Precision, Medium Preload, Duplex Universally Ground

Product Description

What this part is

Super precision angular contact ball bearings for a machine tool spindle, 80 mm bore, 125 mm outside diameter, 22 mm width — the same envelope as an ISO 7016. These are the high-speed B-prefix spindle type: 30° contact angle, machined phenolic cage, EP7 precision grade, faces universally ground so the bearings come up to a specified medium preload when mounted as a duplex set.

Decoding the designation

B – RHP/NSK high-speed spindle bearing series prefix
7016 – angular contact ball bearing, 80 mm bore, 80x125x22 mm envelope
X2 – internal design variant. This element is not decoded from any manufacturer source we can verify, and it is deliberately not interpreted here
T – machined phenolic cage
A – 30° nominal contact angle, read in the NSK scheme
DUM – duplex, universally ground, medium preload
EP7 – RHP/NSK precision grade; EP7 approximates ISO class 4 / ABEC 7

A caution on the contact-angle letter. Suffix schemes are brand-specific and the same letter means different angles across makers: in the NSK scheme A is 30°, C is 15° and A5 is 25°, whereas SKF uses AC for 25° and RHP’s own 70-series numbers use E for 25°. This decode is read in the NSK scheme because RHP’s super precision line became NSK’s. If your application is angle-critical, confirm the angle against the current NSK catalogue rather than against a cross-brand letter.

Correcting the source data

The listing previously carried “Made In England” as a condition note and “England” in the title. No carton or ring marking has been verified to support an origin claim, and origin errors on surplus super precision bearings are common enough that we do not repeat them, so no origin is claimed on this page.

What these specs mean in practice

The 30° contact angle is the axial-rigidity end of the range. The steeper the angle, the more of each ball’s contact load acts along the shaft axis, so thrust capacity and axial stiffness are markedly higher than a 15° C bearing in the same envelope. That is what you want where axial deflection sets the accuracy — heavy face milling, drilling thrust, a preloaded screw drive, a vertical spindle. The trade is speed: steeper angles raise ball centrifugal and gyroscopic effects and load the cage harder, so the permissible speed and thermal headroom are lower than the 15° version of the same size.

Medium preload sits between light and heavy. Preload takes out internal looseness so balls roll rather than skid and stiffness becomes predictable; more preload means more stiffness and more friction heat. Medium is the general-purpose and light-roughing choice, and it pairs sensibly with a 30° angle, where the point of the bearing is rigidity rather than maximum rpm.

The phenolic cage is light, damps vibration and retains lubricant in its own porosity, which is why phenolic-caged bearings tolerate marginal lubrication far better than steel or brass. Phenolic sets an upper operating temperature, so it is the wrong cage for a hot, uncooled housing.

EP7 is the precision grade, approximately ISO class 4 / ABEC 7. It is a statement about running accuracy — bore, outside diameter and above all radial and axial runout — and it only reaches the workpiece if the shaft and housing are machined to a matching standard.

Quantity and configuration

The source listing describes this as a set, and DUM designates duplex universal grinding at medium preload, so it is offered as a matched duplex set rather than a loose single. Because surplus duplex sets are frequently split, please confirm the piece count with us before ordering if the number of bearings matters to your build. What is certain either way is the design intent: a duplex position takes two bearings of this identical designation, and mixing designations, angles or preload grades in one set defeats the reason for buying preload-matched bearings.

Fitting notes

Mount in the ground orientation. A universally ground bearing has a defined high face and low face, and the medium preload the grind establishes only appears when the marked faces meet as intended. Choose the arrangement deliberately: back-to-back (DB) for maximum radial and moment stiffness, which is the normal spindle answer and the one that lets a pair resist shaft tilting; face-to-face (DF) where shaft-to-housing alignment cannot be held tightly; tandem (DT) where two bearings share thrust in one direction.

Precision practice throughout: clean, round, burr-free shaft and housing seats to the tolerances an EP7/P4-class bearing assumes; even, symmetrical clamping so no ring is pinched out of round; a controlled fill of clean lubricant, because over-greasing a preloaded spindle bearing raises running temperature and pushes the preload away from its set value. Never hammer, and never let mounting force pass through the balls.

Published ratings and mounting data

Basic dynamic load rating, basic static load rating and limiting speed are left blank. NSK’s super precision bearing tables were not retrievable at the time of writing, and the X2 design variant in particular cannot be assumed to share the ratings of a standard 7016A. Borrowing a standard-design or different-angle figure onto this page would be a guess dressed as a specification, so the cells are empty; take the values from the current NSK super precision catalogue.

Interchange guidance

RHP is now NSK, and NSK continues this line, so the B7016 high-speed spindle family is the place to look for a current equivalent. Useful search forms include B7016X2TADUMEP7, B7016X2 TADUM EP7, B7016X2TADUM, and the base 7016A for the 30° envelope. Same-envelope 30° bearings from other makers use their own schemes and their own internal designs — treat them as candidates to verify, not as drop-ins. Central Surplus also stocks RHP 7016CTSULP4 in this identical 80x125x22 envelope; that is a 15°, light-preload, single universally ground bearing, so it fits the same hole but gives a faster, less axially rigid spindle. It is an alternative, not a substitute.