SNR7205CG1DUJ84Super Precision Angular Contact Ball Bearing 25x52x15 mm, 15 Degree Contact Angle, Stratified Phenolic Cage, Universal Duplex Pair Medium Preload, ISO Class 4

Product Description

What this part is

An SNR Machline super-precision angular contact ball bearing, 25 mm bore × 52 mm outside diameter × 15 mm width, 15° contact angle, supplied as a universal duplex pair at medium preload and held to ISO class 4. Mounted as a pair the set occupies 30 mm of shaft length. SNR is part of the NTN-SNR group, and Machline is its machine tool spindle range.

Decoding the designation

SNR’s suffix scheme is opaque until someone spells it out, so here it is in full:

7205 — ISO 72-dimension series angular contact, 25 × 52 × 15 mm.
C — 15° contact angle in SNR’s scheme. SNR uses C for 15° and H for 25°.
G1 — an SNR internal-design variant of the C-type Machline bearing. SNR does not publish a definition of this letter code, so no meaning is asserted for it here.
DU — duplex universal, flush ground. Two bearings, mountable back-to-back, face-to-face or in tandem, with the preload produced by clamping alone.
J84 — preload and precision combined in one code. The middle digit gives preload class, where 7 is light and 8 is medium; the final digit gives precision, where 4 is ISO class 4. So J84 means medium preload, ISO class 4 — confirmed against SNR’s own published data for this part number.

That J-code structure is the useful takeaway: it is not a grease code and not a matched-set code. The set information lives separately in the DU block, and preload plus precision live in the J block.

What these specs mean in practice

15° is the high-speed spindle angle. It biases the bearing toward radial load, runs cooler than a steeper angle at the same rpm, holds radial running accuracy better and reaches a higher limiting speed. What it gives up is axial capacity and axial stiffness, so a 15° set is the wrong choice for a heavy one-way thrust position.

Medium preload pushes back the other way: more stiffness and better positional accuracy than a light-preload set, at the cost of some heat and speed headroom. Preload is ground into the ring faces and cannot be adjusted at assembly, so the class is a purchase-time decision, not a fitting-time one.

The stratified phenolic cage — cotton-fabric-reinforced phenolic, machined and guided on the outer ring land — is a genuine specification that distributors routinely omit. Phenolic damps ball-passage excitation, tolerates marginal lubrication far better than steel or brass, and is what makes the published speeds achievable. Its constraint is temperature: the published operating range is −40 to 120 °C.

Published ratings and mounting data

Dynamic load rating Cr — 17.6 kN (3,957 lbf), single bearing
Static load rating Cor — 11.1 kN (2,495 lbf), single bearing
Limiting speed — 27,000 rpm grease, 42,000 rpm oil
Axial load centre offset a — 13 mm
Assembled pair width — 30 mm
Operating temperature range — −40 to 120 °C
Internal geometry — d2 34.0 mm, D1 44.5 mm, D4 46.9 mm, D5 36.8 mm; r2 max 1.0 mm, r3 max 0.3 mm

Ratings are per single bearing, from SNR’s data for the matching single, which uses the same rings. SNR publishes no set rating for the duplex item, so for a mounted pair apply the standard duplex factors rather than doubling — the two bearings do not share load equally. Ball count, ball diameter and preload force in newtons are not published.

Quantity and configuration

DU designates a matched pair ground as a set. Surplus duplex stock is regularly split, so no pair-count claim is published on this listing. Only bearings from a common original set will produce the specified medium preload when clamped together.

Fitting notes

Keep the pair together and align the etched face marks as ground. Observe thrust direction on each bearing. Avoid aggressive solvent flushing of the phenolic cage, and confirm the position stays inside the 120 °C limit. Bearings ship preserved rather than charged with service lubricant. ISO class 4 running accuracy is only realised if the shaft and housing seats are ground to matching tolerance.

Interchange guidance

The carton cross-reference 7205C-T-DUM-P4 checks out cleanly and is a genuine equivalent: C denotes 15° in both schemes, T is the machined phenolic cage, DUM is duplex universal medium preload matching SNR’s J84, and P4 is ISO class 4. Also worth searching: B7205-C-T-P4S-DUM in Schaeffler format and 7205CD in SKF format, where plain C denotes 15°.

A 2MM205WI CR DUM marking also circulates against this envelope, and in the Fafnir/Timken scheme 2MM likewise denotes 15°, so that one is angle-consistent too. Be careful in the other direction, though: 7205A5 is 25° and 7205A is 30° in NSK’s scheme, and neither substitutes for a 15° bearing despite sharing the identical 25 × 52 × 15 envelope. NTN-SNR is the current source.