Ball (bearing)

Bearing balls are special, highly spherical and smooth balls. They are most commonly used inside ball bearings, but they also serve as components in other devices such as freewheel mechanisms. The balls themselves are often called ball bearings, which is an example of a synecdoche, the part standing for the whole. They are made in many different grades, and the grades are defined by standards bodies such as the American Bearing Manufacturers Association, which sets standards for the precision of bearing balls. They are manufactured in machines designed specially for the job. In 2008 the United States produced 5.778 billion bearing balls, a figure that shows how large a component business rests on such a small part.