SKF7024CTCC78Angular Contact Ball Bearing – 120 mm ID, 180 mm OD, 28 mm Width, Open, 15°, Light preload.

Product Description

What this part is

An SKF 7024CTCC78 single row angular contact ball bearing. Bore 120 mm, outside diameter 180 mm, width 28 mm. One row of balls on a 15 degree contact angle, straight bore, open on both faces, supplied to ABEC 5 running accuracy at light preload. This is a spindle-class bearing rather than a general purpose ball bearing: the raceways are ground to closer tolerances than a standard 7024 and the bearing is intended to be mounted against a second bearing in a preloaded set.

Decoding the designation

7024 places the bearing in the 70 dimension series at a 120 mm bore. C is SKF’s code for a 15 degree contact angle. TC and C78 are SKF execution and tolerance suffixes belonging to the older North American super-precision range; the same CTC/C78 combination appears across that family, for example on a 7009 CTC/C78. The carton also carries 2M9124WI CR, the Fafnir interchange for the same envelope, and ABEC5.

What these specs mean in practice

A 15 degree contact angle is the shallow end of the angular contact range. It carries axial load in one direction and favours speed and radial stiffness over thrust capacity, which is why 15 degree bearings are the usual choice for machine tool spindles and other high speed positioning work. Published radial dynamic load capacity is 114 kN and static capacity is 122 kN, with a limiting speed of 7000 rpm.

Light preload sets the working clearance negative from the start, so the balls stay loaded and the shaft has no radial or axial play at rest. That is what gives a spindle its stiffness and its repeatability under cutting load. Light preload is the lowest of the standard grades and trades a little stiffness for lower running temperature and a higher speed ceiling.

Because the bearing takes thrust in one direction only, it is mounted in pairs or larger sets. Two bearings back to back give axial location in both directions and high moment stiffness; face to face is more tolerant of misalignment; tandem shares thrust in one direction between two bearings.

Published ratings and mounting data

Bore: 120 mm (4.7244 in)

Outside diameter: 180 mm (7.0866 in)

Width: 28 mm (1.1024 in)

Contact angle: 15 degrees

Rows of balls: 1

Radial dynamic load rating: 114 kN (25,628 lbf)

Radial static load rating: 122 kN (27,427 lbf)

Limiting speed: 7000 rpm

Running accuracy: ABEC 5 (P5)

Preload: light

Closure: open, no seals or shields

Operating temperature range: -30 to +150 degrees C

Approximate mass: 4.61 lb (2.09 kg)

Quantity and configuration

Priced and sold per bearing. Sets are built by ordering the number of pieces the arrangement calls for.

Fitting notes

Angular contact bearings are directional. The wide shoulder of the outer ring carries the thrust, and the ring faces are marked so that a set can be assembled in the intended orientation. Mounting force is applied squarely to the ring being fitted and never passed through the balls. Abutment faces on the shaft and in the housing are ground square to the axis, since an out of square face tilts the ring and loses the running accuracy the bearing was ground for. Open bearings are supplied without lubricant and are greased or oil fed on assembly.

Interchange guidance

The 120 x 180 x 28 mm envelope at 15 degrees is shared across the precision bearing makers. Comparable designations include SKF 7024 CD/P4A, NSK 7024CTYSULP5 and 7024CTRSULP3, Fafnir 2MM9124WI-CR, FAG B7024C.T.P4S and NTN 7024CGD2. Contact angle is the dimension that must match: an SKF 7024 ACD/P4A is a 25 degree bearing in the same envelope and is a different part, as is any A5 suffixed NSK. Precision grade and preload class also need to match the position, since a P5 light preload bearing and a P4 medium preload bearing of the same number behave differently in a spindle.