RHPSuper Precision Angular Contact Ball Bearing 30x55x13 mm, 25 Degree Contact Angle, Phenolic Cage, Duplex Universal Medium Preload

Product Description

What this part is

A super-precision angular contact ball bearing in the 70-series, 30 mm bore × 55 mm outside diameter × 13 mm width, built for machine tool spindle service. RHP is the British bearing maker now part of NSK, and legacy RHP spindle bearings remain widely specified for grinding and milling spindle rebuilds.

Decoding the designation

7006 is the ISO 70-series angular contact envelope, 30 x 55 x 13 mm. E is a 25° contact angle: in this scheme C denotes 15° and E denotes 25°, the high-angle variant. T is a machined laminated phenolic cage, outer-ring guided; phenolic runs quieter and tolerates higher speed than steel or brass, and is the standard spindle cage material. DUM is duplex universal, medium preload: universally ground faces mean the two rings can be assembled back-to-back, face-to-face or in tandem and the preload comes out correct without shims. P6 is ISO tolerance class 6, equivalent to ABEC 3.

What these specs mean in practice

The 25° contact angle is the trade-off that decides whether this bearing suits your spindle. Against a 15° bearing it carries substantially more axial load and holds axial stiffness better under thrust reversal, but it generates more heat at speed and gives up top-end rpm. It suits milling and drilling spindles where thrust dominates; a 15° bearing suits high-speed grinding where radial running accuracy and speed matter more. Medium preload sits between light and heavy: more stiffness and better positional accuracy than light preload, less heat generation and longer grease life than heavy. Once a duplex set is ground to a preload class the preload is built into the ring faces. Contact Angle: 25°. Cage Material: Laminated phenolic. Precision Class: P6 (ISO class 6 / ABEC 3).

Quantity and configuration

DUM denotes a matched duplex set, ground and marked as a pair for back-to-back, face-to-face or tandem mounting. Supply state: preserved for storage, with the service lubricant applied at build.

Mounting data

Ring pairing: the faces are ground as a unit, so the rings of a duplex set stay together. Face marks: the etched face marks align when the set is stacked.

Interchange guidance

The ISO equivalent designation is 7006E-T-P4S-DUM in the Fafnir/Timken world number scheme and B7006-E-T-P4S-DUM in Schaeffler format. This bearing is marked P6, a lower tolerance class than the P4 super-precision bearings usually specified for spindles; match tolerance class as well as envelope when substituting. RHP spindle bearings were absorbed into NSK, which is the current source for a new-production equivalent.