NSK7928CTYNSULP4Super Precision Angular Contact Spindle Bearing 140 x 190 x 24 mm 15 Degree Contact Angle ABEC 7 P4 Light Preload Universally Ground Single

Product Description

What this part is

NSK 7928CTYNSULP4 super-precision single-row angular contact ball bearing. Bore: 140 mm. Outside Diameter: 190 mm. Width: 24 mm. Series: 79, ISO base designation 71928. Contact Angle: 15°. Precision Class: ISO P4, equivalent to ABEC 7. Preload Class: light. Cage: moulded polyamide, ball-guided. Closure: open. Grinding: single, universally ground. Rolling Elements: steel balls. A thin-section, large-bore spindle bearing for machine-tool spindle noses, grinding and boring spindles, rotary tables, indexing heads and large-diameter positioning axes.

Decoding the designation

7928: 79-series single-row angular contact ball bearing, 140 mm bore. C: 15° contact angle in NSK’s scheme. TYN: moulded polyamide cage, ball-guided. SU: single, universally ground. L: light preload. P4: ISO tolerance class 4, ABEC 7. Searchable forms of the designation: 7928CTYNSULP4, 7928C TYN SUL P4, 7928-C-TYN-SUL-P4, 7928C, 71928, 71928-C, 71928CTYNSULP4.

Published ratings and mass

Basic Dynamic Load Rating (Cr): 100 kN. Basic Static Load Rating (C0r): 95.5 kN. Permissible Axial Load (Pa): 58.0 kN. Limiting Speed, grease lubrication: 7,000 rpm. Limiting Speed, oil or oil-air lubrication: 8,500 rpm. Effective Load Centre (a): 34.1 mm. Mass: 1.63 kg (3.59 lb). Recommended grease quantity: 9.2 g per bearing. Calculation factor f0: 16.7.

Preload and axial rigidity

Preload force and rigidity for this bearing in a back-to-back or face-to-face pair, by preload class. Light (L): 632 N preload, 150 N per micrometre axial rigidity, measured axial clearance –19 micrometres. This bearing is the light class. Extra light (EL): 334 N, 115 N per micrometre. Medium (M): 1,459 N, 217 N per micrometre. Heavy (H): 2,967 N, 308 N per micrometre. Light preload runs cooler, tolerates higher speed and accommodates more thermal growth in shaft and housing; it gives the least axial stiffness of the four classes. Preload classes are matched across a whole stack, since a mixed stack clamps up to a preload neither bearing was ground for.

Abutment and fillet dimensions

Chamfer Dimension r (min): 1.5 mm. Chamfer Dimension r1 (min): 1 mm. Diameter of Shaft Abutment da (min): 149 mm. Diameter of Housing Abutment Da (max): 181 mm. Diameter of Housing Abutment Db (max): 184 mm. Radius of Shaft or Housing Fillet ra (max): 1.5 mm. Radius of Shaft or Housing Fillet rb (max): 0.8 mm.

What a 15° contact angle buys

A 15° bearing carries its load closer to the radial plane than a 25° or 30° bearing. The shallower angle puts less centrifugal and gyroscopic loading on the balls, generates less heat and less contact spin, and raises the speed ceiling. Thrust capacity and axial stiffness are lower than a steeper angle delivers. That is the trade for high-speed, lighter-cut duty such as grinding and high-rpm milling. Thrust-dominated boring and facing spindles use a steeper angle.

What universal grinding lets you do

Universally ground rings are ground to a controlled face offset, so any two or more bearings of this designation come up to the intended preload when clamped together in any orientation, with no shims and no factory-matched set paperwork. Arrangements available from universally ground singles: back-to-back (DB) for maximum moment stiffness and bidirectional thrust, face-to-face (DF) where misalignment tolerance matters, tandem (DT) to multiply thrust in one direction, and triplex and quadruplex stacks.

Quantity and configuration

One bearing. SU is NSK’s code for a single universally ground bearing, as distinct from DU, duplex, which describes a pair supplied together. A single universally ground bearing is a complete building block on its own, and a matched pair, triplex or quadruplex is built from the corresponding number of pieces of the same designation and preload class.

Mounting data

The shoulder and fillet dimensions above give the clearances for the bearing corners. On a thin-section 79-series ring, housing distortion and shoulder squareness matter more than they do on a heavier section.

Interchange guidance

Catalogued as 7928C, 7928CTYNSULP4, 7928-C-TYN-SUL-P4 and under the ISO base number 71928 / 71928-C. Same-envelope 140 x 190 x 24 mm, 15°, P4 universally ground singles: Schaeffler / FAG B71928-C-T-P4S-UL, SKF 71928 CD/P4A, NTN 7928C. RHP precision bearing lines were absorbed into NSK, so an RHP-era spindle part number crosses to an NSK designation. A substitution matches contact angle, preload class and tolerance class, and keeps one cage type within a preloaded stack.