How To Select Bearings

Bearing selection can be a bit confusing sometimes especially in complex applications. But when you get it right, you just sign a deal for optimal performance and longevity of your machinery.

Criteria For Selecting Bearing

Rotational Speed

Every bearing is engineered to perform at its best within a specific speed range. You’ll need different bearings for a system that moves faster than the ones that move slowly. If high-speed bearings are somewhat misaligned, they still need to work safely, and this might have a considerably greater impact when turning swiftly.

Bearing Runabout And Rigidity

Generally speaking, this amount of change is negligible and unimportant. But in some machines such as machine tool spindle systems, the bearing’s static and dynamic stiffness greatly influence the system’s functionality.

Load And Capacity

You can measure bearing load in a few different methods. The shaft receives a radial load at the right angle. Measuring forces acting in the same direction as the shaft is possible with axial load. You can combine axial and radial loads to work together to make a moment in a system. Over its anticipated range, a bearing must be able to support all three kinds of loads.

Tolerance

The ISO and JIS standards define the dimensions and rotational performance of cylindrical roller bearings with spacers. For machines that require great precision and speed, it’s advisable to employ pathways with an accuracy level of 5 or higher. Devices that require extreme precision can make use of deep groove ball bearings, radial thrust ball bearings, or cylindrical roller bearings.

Temperature

To get the most out of a spinning system, you must comprehend how temperature fluctuations affect its components. Journal bearings can generate a great amount of heat in a system, and it’s crucial to understand how they respond to heat from other sources. You need to adjust the lubrication of the bearing for the temperature you want to use it for.

Bearing Lubrication

Knowing your bearing lubrication requirement is another factor to consider. This is because improper lubrication is one major reason bearing fails. Lubricating your bearing will create a film of oil between the rolling elements and the bearing raceways which helps to prevent overheating and friction. If your application is a high-speed application, then you need to calculate the n*dm value. You’ll know the grease is not capable of providing enough lubrication if the n*dm value is greater than the maximum speed of the grease.

Friction Torque

Ball bearings are less susceptible to friction than roller bearings. When you subject radial contact bearing to a pure radial load, the friction resistance is minimal. Friction resistance usually arises in an axial contact bearing under pure axial load.

Rotational Accuracy

The majority of journals with O-level tolerance bearings are sufficient to satisfy the host’s requirement. Nevertheless, you can utilize higher tolerance deep groove ball bearings in applications like machine tool spindles, precision machinery, and instruments where the accuracy of the shaft’s rotation is important.

Sealing

A retention compound is also known as a sealant. It’s used to lessen excessive evaporation and lubricant contamination. There are two main types. The first is a shield-like encasement that is a component of the bearing and is frequently made of the same materials. When high load temperatures and speeds are not a problem for the operation, these shields can alternatively take the shape of a rubber seal. The alternative approach involves adding a retention compound to the spinning component’s shaft. When you fit the bearing, the inner ring will pull an even bead-on compound down the shaft to fill in any assembly flaws.

Maintenance

Maintenance in this aspect consists of three types which are preventive, reactive, and predictive. To guarantee continual activities the three are essential. However, you must utilize renewed maintenance if your equipment is equipped with special bearings. For instance, bearings that use lubricants based on oil need more frequent maintenance. Furthermore, cheaper bearings may require more frequent predictive and preventive maintenance. which could raise the overall cost. Unlike unbranded bearings, bearings from reliable manufacturers like SKF and INA require less maintenance.

Environment

The operating environment is also a factor to consider when selecting the ideal bearing from your bearing provider. The transmission module needs to use particular lubricants, shields, and bearing material in hostile environments. Seven basic materials are needed to make bearings namely; Polymer plastic, ceramic, stainless steel, carbon steel, chrome steel, and hybrid metals. The most popular materials for bearings are stainless and chrome steel. Ceramic bearings are harder, less prone to corrosion, stronger, lighter, resistant to high temperatures, and require less lubrication and maintenance.

Bearing Installation And Removal

Installing and removing your bearing also depends on your type of bearing, individual preference, and your operating environment. Nevertheless, your available space can also influence it. Generally, bearings that you can easily separate are easier to install and remove. Some include cylindrical roller bearings and needle roller bearings. These are the ideal bearings for applications that require regular inspection.

Misalignment

Mutual inclinations of bearing rings occur in the housing due to manufacturing errors and spindle deflections. You should expect this phenomenon, therefore it’s vital to use bearings that compensate for misalignment and installation errors. These include spherical-roller thrust bearings, double-row spherical roller thrust bearings, and self-aligning ball bearings. These bearings’ inclination angle varies according to their kind, size, and load. If you do not overload them, high-stiffness bearings like ball or roller-contact bearings can make up for little misalignments.

Conclusion

In the process of bearing selection, bear in mind that the load, rigidity, bearing installation and removal, bearing lubrication, temperature, and other factors outlined in this article are important for long-lasting engines and performance.