an overview of ball bearings and their types
An Overview of Ball Bearings and Their Types
A rolling element bearing is a type of bearing used to ensure smooth and efficient operation in machines with rotary motion such as car automobile wheels, engines, turbines, medical equipment, and more. A ball bearing is a type of rolling element bearing that, while facilitating motion, serves three main functions: carrying loads, reducing friction, and positioning moving machine parts. Ball bearings use balls to separate races, reducing surface contact and friction across moving planes. The rotation of the balls creates far less friction than two flat surfaces rubbing against each other. However, because there is less surface contact, ball bearings typically have a lower load capacity than other rolling element bearings of similar sizes.
There are many types of ball bearings with different designs and intended applications, with designs specific to their industrial uses and load type. The most common types of ball bearings are angular contact bearings, axial bearings, deep-groove bearings, linear bearings, self-aligning ball bearings, and high-speed angular contact bearings.
An angular contact ball bearing uses axially asymmetric races. An axial load passes through the bearing in a straight line, while radial loads take a path that axially separates the races. Therefore, the angle of contact on the inner race is the same as the outer race. Ball bearings of this type do a better job of supporting combined loads (simultaneous radial and axial loads) and the contact angle of the bearing should be matched to the relative proportions of each. With higher contact angles, the higher the axial load is supported and the lower the radial load. Axial bearings, also known as thrust bearings, use side-by-side races. In these, an axial load is transmitted directly through the bearing. Radial loads are poorly supported and tend to separate the races, meaning axial bearings are not suited for large radial loads that are likely to damage the bearing.
In deep-groove radial bearings, the race dimensions are similar to that of the balls that run within it. These bearings support higher loads than bearings with shallower grooves. Similar to angular contact bearings, deep-groove bearings support both radial and axial loads, but do not offer the choice of contact angle to better control the relative proportion of these load capacities. Linear bearings, as their name suggests, are designed to allow movement in one direction along a linear axis. Because they generate much less friction than other types of bearings, these are used in many critical industrial applications. Their low friction allows them to run at considerably higher speeds.
A self-aligning ball bearing is a bearing with two sets of self-aligning balls that carry both radial and light axial loads. These bearings are constructed with the inner ring and ball assembly enclosed within an outer ring that has a spherical raceway. This construction allows the bearing to withstand a slight angular misalignment resulting from shaft or housing deflections, improper mounting, or other factors. The final type of ball bearing is the high-speed angular contact bearing. These are similar to angular contact bearings, but are specially designed to tolerate high speeds with precision and accuracy.
The sizes of ball bearings vary according to their intended use, as do the materials they are made from. The majority of ball bearings are made from steel but other common materials include stainless steel, which offers improved corrosion resistance, and hybrid bearings which utilize ceramic balls.