Bearing systems

Short on time? Here’s a quick summary

1. Understanding the floating-fixed bearing principle

The floating-fixed bearing principle is a crucial concept in mechanical engineering that enables the precise and efficient functioning of rotating elements such as spindles. It involves using two specialized bearings that perform different, yet complementary, tasks to ensure stability and flexibility.

This configuration is commonly used in applications like CNC machines, robotics, and other high-precision systems to ensure accurate positioning and repeatability.

So, what's the purpose of this principle? The floating-fixed bearing principle helps minimize unwanted play or movement in mechanical components, thereby enhancing the accuracy and performance of the electromechanical drive system.

2. Bearing systems – What needs to be considered

To enable axial movements of loads and forces using spindle and guide systems, selecting the appropriate bearings or bearing systems is crucial.

In screw jacks, axial and radial bearing of the spindle is an integral part of the design. For custom designs without screw jacks, however, the statics and dynamics of the components "spindle – housing – guide" must be coordinated so that the same dimensioning criteria functionally apply and the required service life values are met by all components.

It is particularly important in bearing dimensioning to strictly separate the construction principles of "fixed and floating bearings" to avoid over-constraining the bearing system. Failure to do so can lead to stresses in the system and significantly reduce its lifespan.

3. What is the role of the fixed bearing?

The fixed bearing plays a crucial role in the axial positioning of the spindle and is also responsible for absorbing the axial forces of the system. It keeps the spindle securely in place, preventing it from moving longitudinally. This is essential to ensure positioning accuracy and to ensure that the spindle remains exactly where it should be, maintaining the necessary precision of the machine. By absorbing the axial forces, the fixed bearing significantly contributes to the overall stability of the system.

4. What is the role of the floating bearing?

In contrast, the floating bearing allows for some axial movement of the spindle, which is particularly important for compensating thermal expansions. With temperature changes, the spindle can expand or contract. The floating bearing permits this movement without causing undesirable stresses or deformations that could affect the functionality or lifespan of the spindle.

5. What to consider when installing a bearing system

Fixed bearings are essential in a bearing system, while the use of a floating bearing is optional and depends on factors such as speed, installation position, and spindle diameter.

The necessity of installing a fixed bearing arises from its role in providing the fundamental stability of the system. Fixed bearings are designed to handle high axial and radial loads, which is crucial for protecting the structure from deformations or damage. They are often placed where the main loads occur and serve as a stable base to absorb and distribute the primary forces transmitted through the system.

6. Conclusion

By intelligently arranging a fixed bearing and a floating bearing, the spindle can operate precisely while adequately responding to changes caused by temperature fluctuations. This principle plays a crucial role in the design and operation of machines that require high precision, such as in manufacturing technology or machine tool construction.