FAGB7030CTPAP4K5ULSuper Precision Angular Contact Ball Bearing 160 x 220 x 28 mm, 15° Contact Angle, P4S / ABEC 7 Class, Phenolic Cage, Extra-Thin 719 Section, Universal Light Preload

Product Description

What this part is

A super precision angular contact ball bearing in the 71932 envelope — 160 mm bore, 220 mm outside diameter, 28 mm width. This is FAG’s spindle bearing range: single row, open, universally ground, and 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 angular contact bearing.
71932 — ISO boundary dimensions in the extra-thin 719 dimension series: 160 x 220 x 28 mm. The 32 is the bore code, 32 x 5 = 160 mm.
C — 15° contact angle in FAG nomenclature. This is the single most important character in the number and the one most often misread.
T — phenolic (textile laminate) cage.
P4S — super precision tolerance: ABEC 7 running accuracy with tighter bore and outside diameter control, plus matched width for universal grinding.
UL — universal grinding, light preload. Any two bearings of this designation clamped together produce the specified light preload with no shims.

What these specs mean in practice

The 719 series is the thinnest section FAG makes in a spindle bearing. At 160 mm bore the ring wall is only 30 mm of radial section, and that slimness is the whole design intent: less mass to accelerate, a smaller outside diameter so the housing and the surrounding spindle structure stay compact, and a lower ball pitch diameter than a 70xx or 72xx section would give at the same bore. All of that raises the speed the bearing can run. The trade-off is load capacity — a thin ring in a large diameter needs a well supported, accurately machined seat and will not tolerate a distorted housing.

The 15° contact angle reinforces the same priority. A shallow angle keeps the ball from climbing the raceway shoulder, which cuts ball spin, friction and heat, so the bearing runs faster and cooler than the 25° (FAG suffix E) version of the same envelope. What you give up is thrust capacity and axial stiffness. If your spindle’s limiting factor is rpm, 15° is right; if it is deflection under heavy cutting load, the E variant is the better tool.

The phenolic cage follows suit. At roughly a fifth the density of brass it puts far less centrifugal load on itself at speed, and the laminate holds a small oil reserve that helps the bearing survive a brief lubrication interruption. In exchange it will not tolerate sustained high temperature, so lubrication needs to be clean and grease fills need to be light. Light preload keeps friction and heat generation to a minimum; medium (UM) and heavy (UH) trade speed for rigidity.

Quantity and configuration

The UL suffix denotes a universally ground single bearing, and one bearing is what ships. Universal grinding is what makes that useful: two or more of these can be clamped into a back-to-back (DB) set for maximum moment stiffness and two-direction thrust, a face-to-face (DF) set where housing alignment is imperfect, a tandem (DT) set to double one-direction thrust, or a triplex stack — each combination developing the specified light preload automatically. Buy one to replace a damaged half of an existing pair, or the matching count to build a complete set.

Fitting notes

Super precision bearings only deliver their accuracy on seats ground to match, and a 719-section bearing is more sensitive to this than most because the thin rings will take up whatever shape the seat gives them. Hold shaft journal and housing bore runout and roundness to a few microns, keep the abutment faces square, and make sure the housing bore is continuous and evenly supported rather than a bolted assembly with soft spots. 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 building a set, keep the marked faces oriented as intended; reversing a bearing changes the preload and can turn a light-preload stack into a clamped one. Lubricate with a spindle grease or an oil mist or oil-air system sized for the bore and speed, and resist over-filling.

Interchange guidance

Same-envelope 15° super precision equivalents include NSK 71932C, SKF 71932 CD/P4A, NTN 71932C and RHP 71932-C-T-SUL-P4, all in the corresponding precision grade. Within FAG, B71932-E-T-P4S-UL is the 25° version of the same envelope — identical dimensions, different contact angle, and not a substitute inside an existing preloaded set. The 71932TGP4 form carried in the source record is retained as a searchable reference. When cross-referencing, match the contact angle, the cage code and the preload class, not just the base number.