How to choose the right bearing

Like plain bearings, rolling bearings reduce friction on a rotating guideway between two components. There are different types of bearings depending on the direction of the force, axial or radial. Bearings consist of rolling elements, usually balls, cylindrical rollers, tapered rollers or needle rollers.

A bearing is a mechanical component whose function is to guide a rotating assembly. Thus, bearings allow one component to rotate relative to another. Bearings are high-precision components that allow equipment to move horizontally at different speeds by efficiently transporting and loading them. A bearing must have high precision and durability, and be able to operate at high speeds with minimal noise and vibration. This type of equipment is used in many projects, such as the automotive industry, aerospace, construction equipment, machine tools, etc. There are many types of bearings, the four main types are: ball bearings, cylindrical roller bearings, tapered roller bearings and needle roller bearings. While ball bearings are the most common device, each type has its own advantages and disadvantages. That's why we recommend that you compare each bearing type to determine which bearing system is best for you.

How to choose bearings?

When selecting a bearing, you must consider several important factors. The first factor to consider is the load the bearing can handle. There are two types of loads:

- Axial load : Parallel to the axis of rotation

- Radial load : perpendicular to the axis

Each bearing is specially designed to support axial or radial loads. Some bearings can accommodate both types of loads at the same time: we call them combined loads. For example, if your bearing must carry combined loads, we recommend that you choose a tapered roller bearing. If you need a bearing that can withstand high radial loads, we recommend cylindrical roller bearings. On the other hand, if your bearings need to support lighter loads, ball bearings may suffice as they are usually less expensive.

Spin speed is another factor to consider. Some bearings can withstand higher speeds. Therefore, cylindrical roller bearings and needle roller bearings with cages have higher speeds than bearings without cages. However, sometimes higher speeds come at the expense of payload.

You also need to account for possible misalignment; some bearings are not suitable for this, such as double row ball bearings. Therefore, attention needs to be paid to the structure of the bearing: embedded bearings and spherical bearings are prone to some misalignment. We recommend that you use self-aligning bearings for adjustment, so that alignment defects caused by shaft bending or installation errors are automatically corrected.

Likewise, operating conditions are also very important when selecting the ideal bearing. Therefore, it is necessary to analyze the working environment when the bearing is in operation. Your bearings can be contaminated in a variety of ways. Some uses may cause noise disturbance, shock and/or vibration. Therefore, your bearings must be able to withstand these shocks without causing inconvenience.

Another fundamental factor to consider is bearing life. Various factors such as speed or repeated use can affect bearing life.

The choice of the sealing system is key to ensure the correct and long-lasting operation of the bearing; therefore, it must be ensured that the bearing is always well protected from any impurities and external factors such as dust, water, corrosive liquids or even used lubricants. The choice depends on the type of lubricant, ambient conditions (and therefore also on the type of contamination), fluid pressure and rotational speed.

To give you a good starting point, fluid pressure is the deciding factor in choosing a seal system. If the pressure is high enough (like in the 2-3 bar range), a mechanical seal is ideal. Otherwise, the choice is directly related to the type of lubricant, grease or oil. For example, for grease lubrication, the most common solutions are: deflectors or gaskets, machined or narrow channels with grooves; in the case of oil lubrication, the sealing system is usually accompanied by grooves for oil recovery.

Conditions of use can also affect your choice, especially when assembling bearings. Consideration must also be given to the rigidity and precision required for the bearing to be used. In some cases, a preload can be applied to the bearing assembly to increase its stiffness. In addition, preload will have a positive impact on bearing life and system noise levels. Note that if you choose preload (radial or axial), you need to know the stiffness of all parts through software or experiment.

In your selection criteria, you must also consider the ideal material for the bearing. Bearings can be made of metal, plastic or ceramic. Bearing material depends on its intended use. We recommend that you choose the most compression resistant bearing. However, the material used affects the price of the bearing.