FAGB7004CBTPAP4DULSuper Precision Angular Contact Ball Bearing Matched Duplex Pair 20x42x12mm 15 Degree P4 ABEC 7 Polyamide Cage Light Preload

Product Description

What this part is

A matched duplex pair of FAG B7004 super-precision angular contact ball bearings, 15° contact angle, glass-fibre reinforced polyamide cage, P4 tolerance class, universally ground for light preload. Each bearing is 20 mm bore x 42 mm OD x 12 mm wide, so the pair stacks to 24 mm overall. The B prefix marks FAG’s spindle-bearing line: high-speed grinding and machining spindles, small ball screw supports, precision indexing heads and instrument spindles.

Decoding the designation

B — FAG super-precision spindle bearing series7004 — ISO angular contact envelope, light series, 20 x 42 x 12 mmC — 15° contact angleTPA — glass-fibre reinforced polyamide cageP4 — ABEC 7 tolerance classDUL — duplex, universally ground, light preload

What these specs mean in practice

15° favours speed and radial capacity over thrust, which is the usual choice at the high-speed end of a spindle. Light preload keeps friction and heat low — on a bearing this small that is what protects the grease and lets it run fast. The polyamide cage is very light, quiet and inexpensive with excellent high-speed behaviour, but it has a temperature ceiling that a phenolic or machined cage does not: sustained running above roughly 120 °C, or exposure to some synthetic oils and aggressive additives, will attack it. Where a machine specifies a T (phenolic) cage for thermal reasons, TPA is not a straight swap.

Published specifications

Bore: 20 mmOutside diameter: 42 mmWidth: 12 mm each bearingTotal width mounted as a pair: 24 mmContact angle: 15°Tolerance class: P4 / ABEC 7Preload: lightCage: glass-fibre reinforced polyamide (TPA)Rows: single row each, mounted as a duplex pairClosure: open

Quantity and configuration

Two bearings, supplied as the matched set. Universally ground rings mean the pair can be arranged back-to-back (DB), face-to-face (DF) or in tandem (DT) and still produce the intended light preload with no spacer. Do not split the pair or substitute a bearing from another set — the preload comes from the matched grind.

Fitting notes

Handle by the rings rather than the cage; polyamide cages are tough but will not survive being levered on. Mark the ring faces before removal so orientation can be reproduced. On a 20 mm bore the fits matter disproportionately — an over-tight interference fit on the bore will raise the preload and the running temperature. Grease sparingly; overfilling a small high-speed pair is the usual cause of early heat failure.

Interchange guidance

Direct equivalents are 7004-envelope 15° P4 light-preload universally ground duplex pairs, including FAG B7004-C-TPA-P4-DUL, Fafnir 2MM9104WI-DUL and NSK 7004CTYDULP4. Related but NOT interchangeable: B7004-E-TPA-P4-DUL is the same envelope at 25°, DUM and DUH carry medium and heavy preload, a T-cage version is a different cage material, and a plain 7004 without the B prefix is a standard-class industrial bearing.