SKF7004CCPA9BDTSuper-Precision Angular Contact Ball Bearing, Matched Tandem Pair – Straight Bore, 20 mm ID, 42 mm OD, 12 mm Width, Open, 15° Contact Angle, Light Preload

Product Description

What this part is

An SKF 7004 CC/PA9B DT super-precision angular contact ball bearing set. Bore 20 mm, outside diameter 42 mm, width 12 mm per bearing, 24 mm across the pair. Open on both faces, one row of balls per bearing, fabric-base laminate phenolic cage. Supplied as a factory-matched tandem pair of two bearings.

Decoding the designation

7004 is the ISO 70 light dimension series on a 20 mm bore. The C reading gives a 15° contact angle. DT marks a matched tandem set of two bearings. The carton also carries the Timken Fafnir designation 2MMV9104WI CR DTL for the same bearing: the leading 9 there is the ISO 70 series so 9104 is a 7004, 2MM is 15°, CR is the outer-land-riding phenolic cage, and DTL is a light-preload duplex tandem set. The two schemes agree on angle, series and cage.

What these specs mean in practice

A 15° contact angle favours speed and radial stiffness over thrust capacity, which is why this execution reaches a 43 000 r/min limiting speed. Basic dynamic load rating is 8.71 kN and basic static load rating 4.3 kN per bearing. Running accuracy is ABEC 9 territory, the tightest class in general spindle use.

Tandem arrangement

In a tandem set both bearings face the same direction, so their contact lines run parallel and the two share a single-direction thrust load between them. That roughly doubles axial capacity in that one direction compared with a single bearing, which is the reason tandem stacks appear on the drive end of loaded spindles.

Preload and clearance

The set is ground for light preload, so clamping the rings axially establishes a defined internal load. Preload replaces running clearance, and a radial internal clearance class therefore does not apply.

Quantity and configuration

Two bearings, one matched tandem set, 24 mm total width.

Fitting notes

Shaft and housing seats are ground to suit the super-precision ring tolerances, and the rings are clamped against ground abutment faces so the ground offsets set the preload as intended. Tandem orientation is marked on the ring faces and both bearings mount the same way round.

Interchange guidance

Timken Fafnir 2MMV9104WI CR DTL is the carton-marked equivalent. FAG B7004-C-T-P2S and NSK 7004CTYNSULP2 are the matching 15° super-precision executions from the other makers. SKF 7004 ACD/P4A shares the envelope on a 25° contact angle, making it a related size rather than a substitution.