A ball bearing is a type of rolling bearing that has the effect of carrying loads, reducing friction, and positioning moving machine parts while facilitating motion.
They reduce contact and friction with surfaces on the moving plane by using two separate "ring gears" or bearing rings. The friction coefficient of a ball bearing is reduced due to the rotational motion of the ball compared to surfaces that rub against each other.
A ball bearing consists of four main parts: 2 rings/races, the balls (the rolling elements), and the retainer (the ball separator). Angular contact ball bearings and radial ball bearings include an inner and outer ring. Angular contact ball bearings and radial ball bearings are designed to support loads in a direction perpendicular to the axis of rotation, called radial loads.
External races are fixed and fitted to the housing. When the radial load is transferred from the bearing to the housing, the outer raceway also assists in this transfer. The inner ring supports and guides the shaft as it rotates and is mounted on the shaft. The role of the rolling elements is to carry and distribute the load over the entire raceway.
The rotational speed of the rolling elements is different from the speed of the inner ring, but they all rotate around the inner ring. The purpose of the separator is to prevent the balls from colliding with each other. The separator is located between the balls. Thrust bearings support loads parallel to the axis of rotation, which are called axial loads. Thrust ball bearings consist of two rings of equal size.
Materials Used in Balls in Ball Bearings
The materials used to manufacture rolling bearing balls vary widely, mainly focusing on the material of the rings. This ensures a coordinated interaction of cage, outer ring and inner ring in the system. This is often important when the application involves heating or cooling of the bearing. The running properties of ball bearings are critical, so they must be good. The most common materials used to manufacture ball bearings and their relationship to ring materials are listed below:
Stainless Steel 1.4401 and 14401
This material is used in ball bearings made of plastic. These stainless steel balls are not hardened. They are particularly resistant to corrosion and are also resistant to salt water and alkalis. Hardened steel balls must not be used in plastic ball bearings. The limits of the material in the plastic ring limit the maximum permissible load of the plastic ball bearing. Stainless steel balls are cheaper than glass balls.
When metal-free ball bearings are required, this is where glass balls come into play. Glass balls are also used when the chemical resistance of the ball bearing is high. Soda-lime glass is used to make bottles, flat glass, drinking glasses and ball bearing materials. The chemical properties of soda lime glass are very good and are suitable for ball bearings that need to be exposed to chemical stress for a short time, but not for large chemical stress. Lemon glass is also named for its light green color.
This material is used in the balls of ceramic ball bearings. Ceramic balls made of alumina are also known as oxide ceramics. They have a polycrystalline structure. These balls are lightweight and have the following properties: good corrosion resistance, good abrasion resistance, and good heat resistance.