The choice of bearing products involves many different aspects. One of them is the bearing clearance. It is the interval that exists between the balls and the inner and outer races of the bearing. Clearance is important for a bearing as it can have an effect on bearing life and other factors related to the cohesiveness of the bearing.
The bearing clearance of a ball bearing is a measure of the geometrical space between three parts, i.e. outer ring, ball, and inner ring. Different clearances may have different functions and features. It is very important for you to choose the proper bearing products. Therefore, before selecting your bearings, it's important to have an understanding of what kind of clearances you are working with. Many things are related with clearance choices.
There are different kinds of clearances. As to the ball bearing clearance, it is necessary to make a distinction between axial and radial. Generally, the axial clearance refers to the space between ball and races parallel to the bearing access, while the radial clearance refers to the give between ball and races perpendicular to the bearing axis.
International code classifies bearings into one of six clearance groups: C1, C2, Normal, C3, C4 and C5. Internal clearance determines bearing classification. C1 and C2 are minimum load clearance bearings. Normal load clearance bearings are used for most applications. C3, C4 and C5 are maximum load clearance bearings.
The shaft and housing you choose will determine the amount of clearance you experience with your ball bearing which is known as the "fit". An interference fit is one in which there is virtually no play between the parts. In a loose clearance fit, there is a great deal of play within the parts.
Load clearance should also be taken into consideration. Dynamic load rating includes rotational stress under load. Load conditions must include average duty, a range of loads or peak loads. Static load ratings apply to bearings rotating at less than 10 revolutions per minute, oscillate slowly or remain stationary under load.
Extremely short duration loads must be calculated because short duration loads may damage the bearings surface. External forces from the transmission of power, rotating shafts or inertia are included in load calculations. Basic calculations assume constant load or direction of force, but bearings are actually subjected to simultaneous radial and axial loads.
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