RHP7205CTDULP4Super-Precision Angular Contact Ball Bearing, 25 x 52 x 15 mm, 15 Degree Contact Angle, ABEC 7 / P4, Phenolic Cage, Universally Ground Duplex, Light Preload – 1 Pc (Half Pair)

Product Description

What this part is

An RHP 7205 C.T.DUL.P4 super-precision angular contact ball bearing, 25 mm bore x 52 mm outside diameter x 15 mm wide, with a 15° contact angle. It is built to ABEC 7 / ISO P4 accuracy with a phenolic cage, and its faces are universally ground so it can be stacked with another bearing of the same designation to give a defined light preload. This is spindle-grade hardware, not a general-purpose bearing.

Quantity and configuration

Read this before ordering: the −1/2PR suffix means half of a pair, so what ships is ONE bearing — 1 Pc — not a matched set of two. That is not a shortfall; it is how universally ground bearings are catalogued and sold. Because the rings are universally ground, a single piece is genuinely useful on its own: it can be run as a single bearing, or matched with any other bearing of the same designation to build a back-to-back (DB), face-to-face (DF) or tandem (DT) set, and the ground offsets deliver the specified preload automatically without shims or spacers. Buy two if you need the pair.

Decoding the designation

7205 — single-row angular contact ball bearing, ISO 72 series, 25 mm bore. 25 x 52 x 15 mm.
C — 15° contact angle in RHP nomenclature. RHP’s other common angle code is E for 25°.
T — phenolic (laminated fabric) cage. Light, self-lubricating and quiet at speed, which is why it is the standard super-precision spindle cage.
DU — duplex universally ground. The ring faces are ground so any two pieces of the same designation stack to a known preload in any orientation.
L — light preload. RHP’s scale runs L light, M medium, H heavy.
P4 — ISO tolerance class 4, equivalent to ABEC 7. RHP also writes this class EP7, which is why the title carries 7205X2TADUEP7.
−1/2PR — half a pair. One bearing.

DU and SU are mutually exclusive: DU means universally ground for duplex mounting, SU means universally ground as a single. This bearing is the DU form.

What these specs mean in practice

The 15° contact angle is the defining spec and it is a deliberate trade. A shallow angle puts the ball load path closer to radial, so the bearing runs faster and cooler and handles radial load well, but it carries less thrust and gives less axial stiffness than a 25° or 30° bearing. That is the right choice for a high-speed spindle where the cutting thrust is modest. Fit a 15° bearing where a 25° was specified and the spindle loses axial rigidity and can deflect under thrust; fit a 25° where 15° was specified and it runs hotter at the same speed. The angle is not interchangeable, and it is the single most common way a super-precision replacement goes wrong.

Preload is the second trade. Preload removes internal clearance, so the spindle gains stiffness and the balls are prevented from skidding at high speed — that is what holds a cutting tool on size. It also generates friction heat continuously, cutting or idling. Light preload is the high-speed choice: less heat, less stiffness. Never mix preload classes in one stack.

Universal grinding is what makes a single piece worth buying. On a non-universally-ground bearing you have to order a factory-matched set and keep the pieces together for life. Here the offsets are ground to a standard, so any two same-designation pieces mate correctly — which also means a stray half found on a shelf can be reunited with another to make a complete working pair.

P4 / ABEC 7 is about running accuracy, not load. It tightens bore, outside diameter, width and runout tolerances so the spindle turns true. That accuracy is worth nothing if the housing and shaft seats are not ground to matching tolerance.

Published specifications

Bore d: 25 mm
Outside diameter D: 52 mm
Width B: 15 mm
Contact angle: 15°
Bearing type: single-row angular contact ball, ISO 72 series
Precision class: ISO P4 / ABEC 7 (RHP EP7)
Cage: phenolic (laminated fabric)
Grinding: universally ground for duplex mounting (DU)
Preload: light (L)
Closure: open
Sale unit: 1 Pc — half of a pair

Installation and setup notes

Handle super-precision bearings clean and cool: unwrap only at the machine, keep the preservative oil on until fitting unless you are flushing to a specified lubricant, and never spin a dry bearing with compressed air. Mount with a press against the ring being fitted, never through the balls. For a duplex stack, check that both pieces carry the same designation, the same contact angle and the same preload letter, and set them in the orientation the spindle drawing calls for — back-to-back for moment stiffness, face-to-face for a self-aligning tendency, tandem for one-direction thrust. Both housing and shaft seats need to be ground to a tolerance that matches the bearing, or the P4 accuracy is wasted.

Interchange guidance

RHP’s bearing business became part of NSK, so the current-brand equivalent is an NSK 7205 super-precision at 15°. 2MM205WI-CR-DUL is carried on this listing as the Fafnir and Timken designation for the same bearing: the 2MM prefix is Fafnir’s 15° code, CR is a phenolic outer-land-riding cage and DUL is duplex universally ground light preload — a genuine like-for-like interchange, and its 15° independently confirms the RHP C code. Other same-angle equivalents: FAG B7205-C-T-P4S-UL, NSK 7205 CTYDULP4, SKF 7205 CD/P4A, NTN 7205 C GD2GLP4. Beware the near-misses: Fafnir 3MM205WI is 25°, NSK 7205 A5 is 25° and 7205 A is 30°, and SKF 7205 ACD is 25°. Those are dimensionally identical — same 25 x 52 x 15 mm envelope — but they are related sizes with a different contact angle, not equivalents. Always carry across the contact angle, the grinding code and the preload letter as well as the size.