NSK7206A5TYDUMMatched Pair Super-Precision Angular Contact Ball Bearings, 30x62x16 mm Each, 25° Contact Angle, Medium Preload, Polyamide Cage, P4

Product Description

What this part is

A universally ground duplex pair of NSK super-precision angular contact ball bearings, 30 mm bore by 62 mm outside diameter by 16 mm wide per bearing, open, with a moulded polyamide cage and medium preload.

Decoding the designation

7206 — angular contact ball bearing, 72 dimension series, 30 mm bore
A5 — 25° contact angle. NSK’s plain A is 30° and C is 15°, so 7206A, 7206A5 and 7206C are three different bearings in the same envelope
TY — moulded polyamide resin cage, ball guided
DUM — duplex, universally ground, medium preload; mountable DF, DB or DT with no shimming

Published ratings and mounting data

Figures below are per single bearing, from NSK super-precision catalogue data for this designation:

Basic dynamic load rating, Cr — 23.2 kN
Basic static load rating, C0r — 14.1 kN
Permissible axial load, Pa — 12.0 kN
Limiting speed — 21,800 rpm grease lubricated, 30,000 rpm oil lubricated
Effective load centre, a — 18.7 mm
Chamfer dimensions — r min 1 mm, r1 min 0.6 mm
Shaft abutment diameter, da min — 36 mm
Housing abutment diameters — Da max 56 mm, Db max 57 mm
Fillet radii — ra max 1 mm, rb max 0.5 mm
Mass — 0.194 kg per bearing

Note the sanity check: static rating below dynamic rating is normal and correct for a ball bearing of this size, and these figures are consistent. Preload force and axial rigidity are not quoted, because NSK publishes those per preload class and the published values readily available were for the light class, not the medium class fitted here.

What these specs mean in practice

25° is the middle ground: roughly double the axial capacity and axial stiffness of a 15° bearing in the same envelope, at the cost of some top speed. Medium preload firms the arrangement up further and runs a little warmer than a light set. The polyamide cage is quiet, light and cheap to run at speed, but it sets a temperature ceiling around 120 °C, so oil-mist spindles running hot want a phenolic or machined-brass cage instead.

The abutment dimensions above are the ones people skip and then regret. The shaft shoulder must be at least 36 mm diameter and the housing shoulder no more than 56 mm, or the shoulder fouls the wrong ring and the bearing is loaded through the cage. The effective load centre of 18.7 mm is what you need to calculate the induced axial force under radial load and the real span of a DB pair.

Quantity and configuration

Sold as matched pairs of two bearings. Stock shows 11, and whether that counts pairs or individual bearings is not established, so no firm piece count is claimed. Do not split a universally ground pair — the medium preload only exists as the set.

Interchange guidance

25° bearings in the same envelope from other makers: SKF 7206 ACDGB/P4A (AC = 25°), Fafnir/Timken 3MM206WI DUM (3MM = 25°), FAG B7206-E (E = 25°) and NTN 7206A5; on the FAG and NTN numbers the full suffix sets cage, class and preload. NSK 7206A5TYNSULP4 – light-preload universal single, not a medium-preload pair. Do not substitute a 15° or 30° bearing on envelope alone.