Bearing Selection
The selection of bearings is an important factor in the successful operation of any rotating machine. To ensure a long service life and efficient operation of the machine, it is important to choose the right bearing for the job. This article provides an overview of the main aspects to consider when selecting a bearing.
The first factor to consider when selecting a bearing is the type of bearing needed. There are two main types of bearings: fluid-dynamic bearings and rolling element bearings. Fluid-dynamic bearings consist of two circular plates, between which lubricant (usually oil or grease) is used to reduce friction and prevent metal-to-metal contact. Rolling element bearings consist of two, or sometimes more, rows of metal balls or rollers, which act as a low-friction interface between the inner and outer rings. Depending on the application, different types of bearings will be suitable; understanding the different types is key to selecting the right bearing.
The next factor to consider when selecting a bearing is the load capacity required. The load capacity of a bearing is the amount of weight it can support before it begins to experience failure. This will be determined by the application; for example, linear motion bearings need to be capable of accommodating the axial load generated by the application, whereas radial bearings will need to be able to cope with the radial load. Knowing the load direction and magnitude at which the bearing will operate is a key part of selecting the right bearing.
The third factor to consider when selecting a bearing is its material. Bearings are made from a wide range of materials, including steel, stainless steel, titanium, and various plastics. The choice of material will be determined by the application; for example, a bearing intended for use in a wet environment may require stainless steel or titanium to resist corrosion, while a bearing operating at high temperatures may require a plastic-based material to minimise wear and tear.
The fourth factor to consider when selecting a bearing is its wear properties. Wear is the result of the moving parts of the bearing rubbing together, which may cause damage over time. The rate of wear will depend on the bearings design, as well as the application environment; for example, acidic or salt-filled environments will increase the rate of bearing wear. Choosing a bearing with abrasion-resistant materials or coatings can help to reduce the rate of wear and elongate the bearings service life.
Finally, the cost of the bearing should be taken into account. Generally, the more expensive bearings tend to provide greater precision and reliability. Therefore, cost should be taken into consideration in the context of the total cost of ownership of the machine, as the long-term cost of replacing a low-quality bearing can sometimes be greater than the initial cost of the bearing.
In summary, the selection of a bearing is a critical factor in the success of any rotating machine. By understanding the different types of bearings, their load capacities and materials, as well as the rate of wear and cost considerations, it is possible to select the right bearing for the job.
