NSKB71906ETPAP4ULSuper-Precision Angular Contact Ball Bearing 30 x 47 x 9 mm, 25° Contact Angle, ABEC 7, Polyamide Cage, Universal Light Preload

Product Description

What this part is

A FAG B71906-E-TPA-P4-UL super-precision angular contact ball bearing, 30 mm bore, 47 mm outside diameter, 9 mm wide. This is a machine-tool spindle bearing in the super-light 719 section: raceways ground to super-precision running accuracy, a 25° contact angle, and ring faces prepared for matched stacking. A single-row angular contact bearing carries thrust in one direction only, taking that thrust and its radial load through the same contact ellipse.

Decoding the designation

B7 is the FAG super-precision spindle bearing series. 19 is the ISO 719 super-light dimension series and 06 the bore code, giving 30 mm at five millimetres per unit. E sets the contact angle at 25°; a C in that position would be 15°. TPA is the glass-fibre reinforced polyamide cage. P4 is ISO tolerance class 4, equivalent to ABEC 7. UL is the universal design at light preload.

What these specs mean in practice

The 719 super-light section is what buys the compactness: 8.5 mm of radial section and 9 mm of width across a 30 mm bore, so the bearing fits a slim spindle nose or a stacked set in a short housing. The 25° contact angle carries more thrust and less speed than a 15° bearing of the same size and gives greater axial stiffness for a given preload, which suits a spindle seeing real cutting thrust rather than maximum surface speed. Light preload keeps heat generation and power draw down at the cost of some axial rigidity. The polyamide cage is light and quiet and tolerates shock and momentary lubricant starvation, with a practical continuous ceiling of 120 °C.

Arrangement and matching

The UL universal design means the ring faces are ground so any two bearings of this designation come together at light preload in a back-to-back (DB), face-to-face (DF) or tandem (DT) stack with no spacers or shims. DB gives the widest effective bearing spread and the best resistance to moment load, DF tolerates more misalignment, and DT doubles thrust capacity in one direction only.

Quantity and configuration

1 Pc. Bearing only, open both faces, no seals or shields. Supplied without spacers, without a locknut and without a preload sleeve.

Fitting notes

Super-precision spindle bearings are mounted clean, with the marked ring faces oriented to the intended arrangement, and pressed by an even axial force on the ring being fitted rather than through the balls. The thin 719 section transmits seat form error straight into the raceway, so shaft and housing seats want to be ground to a tolerance matching P4.

Interchange guidance

The genuine interchange is another maker’s 25° super-precision 30 x 47 x 9 spindle bearing at ABEC 7 with universal light preload: NSK 7906A5TYNDULP4, SKF 71906 ACD/P4A, or the FAG HCB71906-E-T-P4S-UL hybrid-ceramic variant. B71906-C-TPA-P4-UL is a related size, not a substitution, because its 15° angle changes the thrust and speed balance, and B71906-E-TPA-P4-UM changes the preload to medium. The plain 7906 carried on this listing is the standard-precision base designation, a related size whose runout is not controlled to P4.