NSK7005A5TRDULP4YSuper Precision Angular Contact Ball Bearing Matched Pair 25x47x12 mm 25° Phenolic Cage Light Preload

Product Description

What this part is

A duplex-ground matched pair of single-row super-precision angular contact ball bearings. Each bearing is 25 mm bore, 47 mm outside diameter, 12 mm width, ground to a 25° contact angle and a light preload band, with a phenolic laminate cage guided on the outer ring. The pair clamps as one unit at 24 mm total width.

Decoding the designation

The 70 prefix and bore code 05 give ISO dimension series 70 at a 25 mm bore. In the NSK scheme A5 is a 25° contact angle — distinct from A at 30° and C at 15°. TR is a machined phenolic laminate cage guided on the outer ring land, rated to a 120 °C ceiling. DU is duplex universal grinding, L the light preload grade, and P4Y an NSK special tolerance class held tighter than standard P4. Two further carton designations agree: 7005E, whose RHP and Timken angle letter E is 25°, and the Fafnir-scheme 3MM9105WI-CR-DUL, whose 3MM prefix is 25° and whose CR is a phenolic outer-land-riding cage.

What these specs mean in practice

A 25° contact angle is the thrust-biased choice in this envelope. Axial capacity and axial stiffness both rise with contact angle, so a 25° pair holds a spindle’s axial position harder under cutting thrust than the 15° version of the same size. The cost is speed: the steeper load line increases ball centrifugal and gyroscopic effects, lowering the limiting speed and adding heat at equal duty.

A phenolic cage guided on the outer ring land is the high-speed cage arrangement. Phenolic is light, so cage inertia and ball-pocket loads stay low, and it retains an oil film well; outer-land guidance keeps the cage stable and running true at speed instead of letting it wander on the ball set. Phenolic sets the temperature ceiling at roughly 120 °C, which governs ahead of the steel.

P4Y is tighter than the ABEC 7 baseline, which is what makes the pair usable where bore and ring runout drive workpiece finish directly. Light preload adds the least friction heat of the preload grades, so it suits fast, moderately loaded spindles and grinding heads, while medium and heavy grades go into stiffer, slower stacks.

Quantity and configuration

Matched pair, 2 Pcs, duplex ground as one set.

Fitting notes

The pair is assembled in the orientation its face marks indicate, most often back-to-back for moment stiffness, and the inner rings are clamped solid against one another so the ground relief sets the preload. A duplex set behaves as a single bearing, and its preload band of a few microns belongs to that specific pair. Shaft and housing seats at this class are ground and measured, typically j4 to k4 on the shaft and H5 to J5 in the housing, and cleanliness governs the result.

Interchange guidance

7005E is the same bearing under the RHP and Timken angle scheme, and 3MM9105WI is the Fafnir-scheme number for the same 25° 70-series size. Same-envelope bearings differing in contact angle, cage, preload grade or tolerance class — 7005C at 15°, 7005A at 30°, the polyamide-caged TY and TYN variants, the medium and heavy preload grades, and standard P4 or P5 class pieces — are related sizes rather than interchanges. A single universally ground bearing of this size is a different item, since SU pieces are not ground to this pair’s stack height.