Introduction
Bearing assembly is an important step in the construction of rotating machines, tools, and other equipment. It begins with the selection of the bearings appropriate for the application and then follows through with mounting the bearings in their housings and securing them in place. The actual assembly design is dictated by the loads encountered in the application, any required speed or precision, special mounting arrangement, and accessibility for maintenance. It is an important but often overlooked aspect in ensuring the reliability of rotating equipment.
Types of Bearings
The selection of bearings depends on the application or conditions in which they are intended to operate. Generally speaking, there are several types of bearings: radial, thrust, combined radial and thrust, four-point contact, and special designs.
Radial bearings, also known as deep groove ball bearings, are the most commonly used type of bearing for most light- to medium-load applications. These bearings are highly reliable in their performance and are capable of operating with only moderate clearance between the internal elements of the bearing.
Thrust bearings are used primarily to support axial loads. They are typically cylindrical or conical in shape and consist of two rotatable surfaces, between which the rolling elements of the bearing form a race.
Combined-radial and thrust bearings are designed to take both radial and axial loads. In a single bearing, part of the bearing will have a double raceway, allowing for both radial and axial load support.
Four-point contact bearings are used to support high radial and axial loads and provide high levels of precision. They consist of four precision surfaces arranged in point contact and are usually mounted between elements using a press-fit procedure.
Special bearings are made in a wide variety of shapes and sizes and have various uses. They include roller bearings and cam followers, spherical roller bearings, and flat bearings.
Bearing Mounting
Bearing mounting is the process of assembling the rotating elements of a bearing into a housing, in order to form a complete bearing assembly. Bearing mounting includes the selection of the proper bearing and housing, the selection of the proper method of assembly, and the selection of the proper lubrication.
The method of mounting a bearing depends mainly on the type of bearing and its application. Generally, bearing mounting can be divided into two main categories: presetting and press-fitting. Both of these methods are discussed in more detail below.
Presetting
Presetting is an assembly method in which the bearing, housing, and other components are assembled before the final installation. This method is often used when assembling large shafts and other high-precision bearings and components. This method eliminates the need to install the bearings out of the housing, which decreases the possibility of contamination during assembly.
Press-fitting
Press-fitting is a popular assembly method in which the bearing, housing, and other elements are assembled together in a single, complete unit. A press-fit process can be used to assemble components ranging from bearings and housings to gears, shafts, and other rotating elements. This method is particularly popular for medium- to high-load applications, as press-fitting eliminates the need for additional assembly steps, shortening the assembly time.
Conclusion
Bearing assembly is an important step in the construction of rotating machines, tools, and other equipment. It begins with the selection of the bearings that are appropriate for the application, after which the bearing and its elements are assembled into a housing or onto a shaft. The actual assembly design is dictated by the loads encountered in the application, any required speed or precision, special mounting arrangement, and accessibility for maintenance. Bearing mounting is the process of assembling the rotating elements of the bearing, and is usually divided into two main categories: presetting and press-fitting.
