FAGB7024CAP4ULSuper Precision Angular Contact Ball Bearing 120 x 180 x 28 mm, 15° Contact Angle, P4S Tolerance, Phenolic Cage, Universal Light Preload

Product Description

What this part is

A super precision angular contact ball bearing in the 7024 envelope — 120 mm bore, 180 mm outside diameter, 28 mm width. Single row, open, universally ground, made to the tolerance grade machine tool builders specify for main spindle positions.

Decoding the designation

B — FAG spindle bearing series, a higher-precision execution than a standard 70-series angular contact bearing.
7024 — ISO boundary dimensions, 120 x 180 x 28 mm.
C — 15° contact angle in FAG nomenclature. This is the character that decides whether a replacement will behave like the bearing it replaces.
T — phenolic (textile laminate) cage.
P4S — super precision tolerance, ABEC 7 running accuracy with tighter bore and outside diameter control and matched widths for universal grinding.
UL — universal grinding, light preload. Any two bearings of this designation clamped together give the specified light preload without shims.

What these specs mean in practice

A 15° contact angle biases the bearing towards speed. The shallow angle limits how far the ball climbs the raceway shoulder, so ball spin, friction and heat generation all drop and the permissible rpm rises compared with the 25° (FAG suffix E) version of the same envelope. The cost is axial load capacity and axial stiffness. Choose 15° when the spindle is limited by speed and thermal growth, 25° when it is limited by deflection under cutting load.

The phenolic cage supports the same goal. Roughly a fifth the density of brass, it generates far less centrifugal stress on itself at high rpm, and the laminate holds a small oil reserve that helps the bearing through a brief lubrication interruption. It is heat-sensitive in exchange, so keep the lubrication clean and grease fills light.

Light preload minimises internal friction and heat rise, which is why it is the default for most spindle positions. Medium (UM) and heavy (UH) buy rigidity at the cost of speed.

Quantity and configuration

UL denotes a universally ground single bearing and one bearing is the sale unit. Universal grinding is the point: clamp two together back to back (DB) for maximum moment stiffness and two-direction thrust, face to face (DF) where housing bores may be slightly misaligned, or in tandem (DT) to double thrust in one direction, and the light preload appears automatically. Three can be stacked as a triplex. Buy one to replace a failed half of an existing pair, or the matching count to build a whole set.

Fitting notes

The mounting has to be as accurate as the bearing. Grind shaft journal and housing bore with runout and roundness held to a few microns and keep the abutment faces square. Mount with controlled heat on the inner ring or a press acting only on the ring being fitted; never drive load through the balls. When assembling a set, keep the marked faces oriented correctly — reversing a bearing changes the preload. Lubricate with a spindle grease or an oil mist or oil-air system sized for the bore and target speed, and do not over-fill.

Interchange guidance

Same-envelope 15° super precision equivalents include NSK 7024C, SKF 7024 CD/P4A, NTN 7024C and Fafnir/Timken 2MM9124WI, where the Fafnir 2MM prefix is 15° and therefore a true angle match. FAG B7024-E and Fafnir 3MM9124WI are the 25° versions of the same 120 x 180 x 28 mm envelope — dimensionally interchangeable but not a like-for-like substitute in a preloaded stack, so they are carried here as dimensional cross-references. The source designation B7024CA.P4.UL is retained as a searchable reference.