# Axial angular contact ball bearings

## Description

Double-acting axial angular contact ball bearings of the 2344 design type are used to mount precision spindles in machine tools. Their design makes them very stiff high-precision bearings with axial preload and tight tolerances. These bearings are designed to be mounted in combination with cylindrical roller bearings in the NN 30.. K or N 10.. K series in the same housing hole. They carry high axial loads thanks to the 60° contact angle.

## Dimensions/standards

In double-acting axial angular contact ball bearings, the hole and outer diameters are standardized according to ISO 15 (Radial bearings – boundary dimensions). The other main dimensions are not standardized but are widely available on the market.

## Tolerances

Due to their stringent use requirements, axial angular contact ball bearings in the 2344 series are highly accurate and are normally produced in the HP tolerance class.

## Bearing design types

Double-acting axial angular contact ball bearings in the 2344 series are designed as detachable bearings composed of solid shaft washers, distance washers, housing washers and ball cage assemblies with solid cages. The bearing components are aligned with one another and can be assembled independently; however, they are not interchangeable with components from other bearings.
To mount the main spindles, the axial angular contact ball bearings are arranged next to a double row cylindrical roller bearing with tapered hole, which carries the radial forces. In bearings in the 2344 series, the nominal size of the outer diameter is the same as in the cylindrical roller bearings in the NN30 series. When the seating faces of the axial angular contact ball bearing and the cylindrical roller bearing are machined together, we obtain the fit clearance; this is because the outer diameter tolerance of the axial angular contact ball bearing is correspondingly defined.

Double-acting axial angular contact ball bearings are produced so that they provide the required operating preload after installation/mounting.

## Cage

Double-acting axial angular contact ball bearings in the 2344 series are normally equipped with ball-guided solid brass cages. The maximal working temperature of brass cages is +150 °C.

## Working temperature

SLF- axial angular contact ball bearings with an outer diameter up to 240 mm are stabilized in dimensions by S0, meaning that they are heat treated to make them usable up to a working temperature of 150 °C. At greater than 240 mm outer diameter, the axial angular contact ball bearings are standard stabilized in dimensions by S1, meaning that they are heat treated to make them usable up to a working temperature of 200 °C. However, as a rule, the maximum operating temperature is not limited by the dimensional stability of the bearing rings and balls. In many cases, it is limited by cage or lubricant. When using brass cages, the maximal working temperature is +150 °C. If you feel uncertain or have specific questions regarding the temperature limits of our bearings, the SLF team is ready to support you.

## Greasing/lubrication & sealing

Double-acting axial angular contact ball bearings are produced without seals; consequently, the bearing location must be sealed around/ on the surrounding components. The sealing must ensure that no moisture and contaminants enter the bearing, and that no lubricant is lost.

Axial angular contact ball bearings are delivered ungreased, but must be lubricated with oil or grease. Choose lubricant according to the application. An oil groove with oil holes is situated in the center of the housing washer. Due to the high-level of conveyor action, the bearings need more oil than, for instance, adjacent cylindrical roller bearings.

## Dimensioning

### Dynamic equivalent load

$$P = F_a$$
 P dynamic equivalent load [kN] Fa axial dynamic load [kN]

### Statically equivalent load

$$P_0 = F_{0a}$$
 P0 static equivalent load [kN] F0a axial static load [kN]

### Static load safety factor

It is possible to verify by means of the static load safety factor S0, whether a bearing’s static load carrying capacity is sufficient for a defined static load.

$$S_{0} = \frac{C_0}{P_0}$$

To make use of the bearings’ precision, the static load safety factor for axial angular contact ball bearings S0 must be >2.5.

 S0 static load safety factor [-] C0 static load rating [kN] P0 static equivalent load [kN]