NSK7208A5TYDULSuper Precision Angular Contact Ball Bearing 40x80x18 mm, 25 Degree Contact Angle, Polyamide Cage, Duplex Universally Ground Light Preload

Product Description

What this part is

An NSK super-precision angular contact ball bearing in the 72-dimension series, 40 mm bore × 80 mm outside diameter × 18 mm width, 25° contact angle, universally ground as a duplex set at light preload. A machine tool spindle bearing.

Decoding the designation

7208 — 72-dimension series angular contact, 40 × 80 × 18 mm.
A5 — 25° contact angle in NSK’s scheme, where C is 15°, A5 is 25°, A is 30° and B is 40°. A 7208A and a 7208A5 are different bearings, not two renderings of one number.
TY — cage code. NSK’s published designation for its moulded polyamide, ball-guided cage is TYN, rated to around 120 °C. TY alone does not appear in NSK’s published cage list and is read here as the polyamide cage.
DUL — duplex universally ground, light preload. The ground faces produce the specified preload when the set is simply clamped together, in whichever arrangement is chosen.

The cross-designation 7208E carried on this part corroborates the angle independently: in the Schaeffler and ISO world-number schemes, E denotes 25°. Two different naming systems agreeing on the same angle is a good identity check.

What 25° and light preload mean in practice

25° is the middle spindle angle — substantially more axial capacity and axial stiffness than a 15° bearing, without the speed penalty and heat generation of a 30° or 40° bearing. Light preload pushes the specification toward speed: the lowest friction and heat of the preload classes, the highest speed capability, and the least axial stiffness. Together, 25° and light preload describe a bearing chosen for a high-speed spindle that still carries genuine cutting thrust.

Preload is ground into the ring faces and cannot be adjusted at assembly, so the class must be right at purchase. And contact angles have to match across a spindle stack — a 25° bearing stacked against a 15° one takes most of the thrust while the shallower bearing runs underloaded and skids, a failure that looks like poor lubrication and is really a specification error.

Published ratings and mounting data

Load ratings and limiting speed are not published on this listing. NSK’s own pages for the base 7208A5 designation were unreachable at the time of writing, and the figures circulating on aggregator sites could not be corroborated against NSK.

One trap is worth naming so it is not repeated later. NSK publishes ratings for 7208A5SN24-series bearings in the region of Cr 34 kN, but SN24 denotes ceramic balls. Those figures describe a hybrid bearing with different internal geometry and different capability, and they do not apply to a steel-ball 7208A5. They were declined rather than borrowed.

Quantity and configuration

DUL designates a matched pair ground as a set. Surplus duplex stock is regularly split, leaving a single bearing in a carton still marked DUL, so no pair-count claim is published on this listing. Confirm the physical piece count before ordering if a complete matched set is required, and note that only bearings from a common original set will produce the specified preload when clamped together.

Fitting notes

Keep the set together and align the etched face marks as ground. Observe thrust direction on each bearing — reversing a single angular contact bearing leaves it unloaded under working load. A polyamide cage is temperature-limited to roughly 120 °C and can be attacked by certain synthetic lubricants and solvents, so confirm compatibility before charging the bearing. Ship preservative should be removed and the correct spindle lubricant applied before running.

Interchange guidance

Angle-equivalent designations at 25° in this envelope: 7208E in ISO world-number style, B7208-E-T-P4S-DUL in Schaeffler format, 7208AC in SKF format where AC denotes 25°, and the 3MM208WI family in Fafnir/Timken format where the 3MM prefix denotes 25°. Note that 7208C is 15° and 7208A is 30°; both share this envelope and neither is a substitute. Because the same-looking suffix letter means different angles in different makers’ schemes, always state which scheme is being read.