Most people take advantage of the utility of ball bearings on a daily basis without giving any thought to how important ball bearings are or how they work. Ball bearings are the most common type of bearing. They can be found everywhere—from computers and semiconductors to airport security systems and garage door openers. They’re even found in microwaves, gas pumps, and lawn mowers. In fact, ball bearings are found in most applications that involve moving parts. Ball bearings are generally used in applications where the load is comparatively small.
The Basics / Concept
The basic premise behind ball bearings is relatively simple: replace a sliding component with a rolling component (ball) to reduce the amount of friction generated. Ball bearings need to be lubricated to operate properly. A bearing that supports a load by placing round elements between the two pieces is known as a rolling-element bearing or a rolling bearing. Ball bearings are one type of rolling-element bearings. Ball bearings use balls to keep the bearing races separate which reduces friction and assists in supporting radial and axial loads. Ball bearings use at least two races to restrain the balls and pass the loads through the balls. Typically one race is immobile while the other is fixed to a rotating assembly such as a shaft or hub. When one of the bearings rotates it causes the balls to rotate too.
Types of Bearings
There are many different types of ball bearings and each can be made from different materials, including ceramic, stainless steel, and chrome steel. For example, commercial, private and military aircraft use aerospace bearings in a lot of applications like jet engine shafts, pulleys, and gearboxes. Materials used to construct these sorts of bearings may include M50 tool steel, carbon chrome steel, 440C stainless steel, silicon nitride, or titanium carbide-coated 440C.
There are many different types of ball bearings; much too many to discuss in detail here. Some common types of bearings include:
- Conrad— Robert Conrad first patented this ball bearing in 1903. It is one of the most common industrial ball bearings and is used in the majority of the mechanical industries.
- Slot-fill— Also known as a full complement design, the slot-fill radial bearing has a higher radial load capacity than a Conrad bearing of similar dimensions and materials.
- Flanged—These bearings have a flange on the outer ring simplify axial location and are very costly to produce.
- Self-aligning—When the inner ring and ball assembly is housed within an outer ring with a spherical raceway, a ball bearing is considered to be self-aligning.
Uses of Bearings
As stated previously, ball bearings are used in a variety of settings. Some common examples include:
- Skateboarding—The wheels in a skateboard contain two bearings in each of the four wheels.
- Inline skates — Ball bearings allow the wheels to rotate freely and smoothly.
- DVD players —Many DVD players contain ball bearings in the tri-saucer disc on top of each base.
- Air conditioners— Window and portable air conditioners frequently use ball bearings to keep the units running quietly.