Vrp Ohlendorf GmbH

Vrp Ohlendorf GmbH in the S719 .. B (HB .. /S) and S70 .. B (HX .. /S) series are designed for high-speed operation and are best suited for light load and low temperature operating conditions.

Features of B design bearings include:

1.asymmetrical inner and outer rings

2. a high number of very small balls

3. a lightweight phenolic resin cage

4. an optimized chamfer design

The asymmetrical bearing rings enable the bearings to accommodate radial loads, and axial loads in one direction. The outer ring shoulder-guided cage is designed to enable good lubricant supply to the ball/raceway contact areas. The shape of the chamfer of the inner and outer rings is optimized for improved mounting accuracy. As a result, mounting is not only facilitated, but there is also less risk of damage to associated components.

When compared to other angular contact ball bearings in the 719 and 70 series, B design bearings have the greatest possible number of very small balls for increased rigidity.

 A non-contact seal is fitted, standard, on both sides of the bearing outer ring. The seal forms an extremely narrow gap with the cylindrical surface of the inner ring shoulder.

Bearing series

The assortment of super-precision bearings presented in this brochure includes two ISO dimensions series:

• the extremely light 719 (HB) series

• the light 70 (HX) series

Bearings in both these series are suitable for high-speed operation and tight radial mounting space. If increased rigidity is required, bearings in the 719 (HB) series are used instead of bearings in the 70 (HX) series, as they contain the greater number of balls, relative to their bore size. Bearings in the 719 (HB) series also accommodate a larger shaft diameter, relative to their outside diameter, when compared to bearings in the 70 (HX) series.

Bearing selection is paramount when dealing with applications that require a high degree of accuracy at high speeds. The many variants of SKF sealed super-precision angular contact ball bearings are well suited to accommodate the conditions dictated by these applications.

The main criteria when selecting bearings in the S719 .. B (HB .. /S) and S70 .. B (HX .. /S) series are:

1. precision

2. rigidity

3. speed

4. load

Precision

When dealing with rolling bearings, precision is described by tolerance classes for running and dimensional accuracy.

When selecting bearings in the S719 .. B (HB .. /S) and S70 .. B (HX .. /S) series, the following should be considered:

1. All bearing variants are manufactured, standard, to P4A (better than ABEC 7)  tolerance class.

2. All bearing variants can be manufactured to the higher precision PA9A (better than ABEC 9) tolerance class, on request. Rigidity

In precision applications, the rigidity of the bearing arrangement is extremely important, as the magnitude of elastic deformation under load determines the productivity and accuracy of the equipment. Although bearing stiffness contributes to system rigidity, there are other influencing factors such as the number and position of the bearings.

When selecting bearings in the S719 .. B (HB .. /S) and S70 .. B (HX .. /S) series, the following should be considered:

1. Ceramic (silicon nitride) balls provide a higher degree of stiffness than steel balls

 A larger contact angle provides a higher degree of axial stiffness.

2. When increased system rigidity is required, bearings in the 719 (HB) series accommodate a larger shaft diameter for a given outside diameter, compared to bearings in the 70 (HX) series.

3. Bearings mounted in a back-to-back  arrangement provide the highest degree of rigidity.

Speed

High-speed applications require cool-running, low-friction bearings like super-precision angular contact ball bearings.

When selecting bearings in the S719 .. B (HB .. /S) and S70 .. B (HX .. /S) series, the following should be considered:

1. Hybrid bearings can operate at higher speeds than comparably sized all-steel bearings.

2. As the contact angle increases, speed  capability decreases.

Load

In high-speed precision applications, the load carrying capacity of a bearing is typically less important than in general engineering applications. Angular contact ball bearings can accommodate radial and axial loads acting simultaneously. When these combined loads exist, the direction of the load also plays an important role in the selection

process.

When selecting bearings in the S719 .. B (HB .. /S) and S70 .. B (HX .. /S) series, the following should be considered:

1. The greater the contact angle, the higher the axial load carrying capacity of the

bearing.

2. The axial load carrying capacity of a bearing arrangement can be increased by adding bearings mounted in tandem