Ball bearings are rolling-elements bearings that reduce rotational friction. The rolling parts in a ball bearing are the balls. They roll between the inner and outer ring and thus, load is transmitted through them. A typical ball bearing has at least 2 balls and they roll in places that are called races. What holds them in place is the cage that keeps them evenly spaced around the races.
Another thing that’s important to know about ball bearings is they are made of steel. The reason behind this is that they have to stand up to a lot of stress and they need to be firm. The standard industry classification for the steel in the bearings is 52100. And when rusting is a potential problem, ball bearings are made out of 440C stainless steel.
The life expectancy of a ball bearing depends on the load it carries and its operating speed. To find out more about them, check out the video below!