Have you ever wondered what is the difference in bearings? Well if you have today I'll give you some insight about what a ball bearing is, and how it can make your life easier! Ball Bearings are a type of rolling-element bearing that uses balls to maintain the separation between the bearing race. The mechanical purpose of a radial bearing is to reduce rotational friction, and support radial and axial load. A ball bearing achieves this by using at least two races to contain the balls and distribute the loads through the balls. In most applications, one race is stationary and the other is attached to the rotating assembly (such as a hub or shaft). As one of the bearing races rotates, it causes the balls to rotate as well. Because the balls are rolling they have a much lower friction than if two flat surfaces were sliding against each other.
Ball bearings tend to have lower load capacity for their size than other kinds of rolling-element bearings due to the smaller contact area between the balls and races. However, they can tolerate some misalignment of the inner and outer races.
Common Elements/Compounds used to manufacture a ball bearing
There are several common designs of ball bearing, each offering various trade-offs. They can be made from many different materials, including: stainless steel, chrome steel, and ceramic (silicon nitride (Si3N4)). A hybrid ball bearing is a bearing with ceramic balls and races of metal.
Common ball bearing designs
Angular contactAn angular contact ball bearing uses axially asymmetric races. An axial load passes in a straight line through the bearing, whereas a radial load takes an oblique path that tends to want to separate the races axially. So the angle of contact on the inner race is the same as that on the outer race. Angular contact bearings better support "combined loads" (loading in both the radial and axial directions) and the contact angle of the bearing should be matched to the relative proportions of each. The larger the contact angle (typically in the range 10 to 45 degrees), the higher the axial load supported, but the lower the radial load. In high speed applications, such as turbines, jet engines, and dentistry equipment, the centrifugal forces generated by the balls changes the contact angle at the inner and outer race. Ceramics such as silicon nitride are now regularly used in such applications due to their low density (40% of steel). These materials significantly reduce centrifugal force and function well in high temperature environments. They also tend to wear in a similar way to steel bearing, rather than cracking or shattering like glass or porcelain.
Most bicycles use angular-contact bearings in the headsets because the forces on these bearings are in both the radial and axial direction.
AxialThe design of axial ball bearings is intended solely to operate with considerable axial load, any radial load is unacceptable for them. Axial ball bearings can accommodate axial loads in one direction only.
As a rule, one of the bearing washers is produced tight to fit on the shaft and the others are loose to be installed in the housing. Axial ball bearings with flat loose washer do not allow any, even slight, angular misalignment between the shaft and the housing. If it is necessary to provide unit operation with initial angular misalignment, bearings with loose sphered seat washers should be used. Usually axial ball bearings are produced split, which simplifies their mounting. Some special applications have stamped protective shield, which makes the whole construction undetachable.
Axial ball bearings are produced with pressed steel cages, with machined cages of brass, steel, aluminum alloys or glass fiber reinforced polyamide.
An axial ball bearing uses side-by-side races. An axial load is transmitted directly through the bearing, while a radial load is poorly supported and tends to separate the races, so that a larger radial load is likely to damage the bearing.
Deep-grooveIn a deep-groove radial bearing, the race dimensions are close to the dimensions of the balls that run in it. Deep-groove bearings can support higher loads. This style is typically used in precision instruments, low noise motor, automobiles, and motorcycles.
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