A ball bearing is a type of rolling-element bearing that uses balls to maintain the separation between the bearing races. The purpose of a ball bearing is to reduce rotational friction and support radial and axial loads.
Where are ball bearings used?
Ball bearings have been around for a long time and have been used in many applications over hundreds of years.
Arguably the most common type of bearing, ball bearings are used in a wide variety of products and applications. From hard drives to skateboards, ball bearings are designed to handle both thrust and radial loads. However, ball bearings are usually found in applications with smaller loads.
In order to serve all these functions, bearings make use of a relatively simple structure: a ball with internal and external smooth metal surfaces, to aid in rolling. The ball itself carries the weight of the load—the force of the load’s weight is what drives the bearing’s rotation.
However, not all loads put force on a bearing in the same manner. There are two different kinds of loading: radial and thrust.
A radial load, as in a pulley, simply puts weight on the bearing in a manner that causes the bearing to roll or rotate as a result of tension. A thrust load is significantly different and puts stress on the bearing in an entirely different way.
If a bearing (think of a tire) is flipped on its side (think now of a tire swing) and subject to complete force at that angle (think of three children sitting on the tire swing), this is called thrust load. A bearing that is used to support a bar stool is an example of a bearing that is subject only to thrust load.
Ball bearings work by transferring the load from the outer race to the ball and onto the inner race. Everything is able to spin smoothly since the spherical shape of the ball only touches the inner and outer races at very small points.
However, this can also be a hindrance as well if the bearing is not used properly. Because of the small area of contact that is holding a particular load, the balls may become deformed and ruin the bearing if it becomes overloaded.
Since ball bearings have proven to do their job well and are also fairly easy to manufacture, they are used in many products and applications. Part of our everyday life, ball bearings are found in things such as blenders and exercise equipment.
The list goes on and on. Bicycles, DVD players, water pumps, washing machines, and fans are just a few of many day-to-day products that we use that use ball bearings.
Aside from everyday objects, ball bearings are also used in more technologically advanced applications as well. For example, the Hubble telescope, the Mars Rover, and weather satellites all use ball bearings.
With continuous use in both old and new applications, improvements in lubrication have helped to extend the life of ball bearings. This has helped to reduce the need for maintenance and replacement. Some ball bearings are sealed and therefore do not require lubricant. Ball bearings that do require lubricant typically use grease.
Ball bearings are the most common type of bearings and are found in many everyday objects, such as skateboards, blenders, bicycles, DVD players, and photocopiers. This type of bearing is typically used in applications that have a high speed and a low load.
Ball bearings consist of two raceways, with a series of smooth metal balls in between, which enable rotation. These balls support the load of the application, as well as reduce friction between the surfaces.
If the load on a ball bearing is too high, there is the risk that the balls may become deformed and cause the bearing to fail prematurely.
It is important that a ball bearing is lubricated effectively, usually with grease, as well as sealed to retain the grease and prevent the ingress of contamination. This is even more paramount in industries where the contamination levels are high, for example in mining & quarrying applications, and in the agriculture industry.