Within a series of thin section bearings, the size of the cross-section remains the same even when the bore size increases. This makes thin section bearings a good choice for applications where space is limited or weight savings is important. However, the thinness of a bearing’s cross-section will result in distortion.
Cross-Sectional Rigidity and Bearing Performance
When a thin section bearing is rigidly supported, cross-sectional rigidity won’t affect performance. But that’s not the case if a bearing is mounted improperly or if its races aren’t supported uniformly. If the fit that’s required for radial support isn’t rigid enough, thin section bearings are more sensitive to deflection under thrust or moment loading. This includes distortions from housings and shafts.
Outer Ring to Housing Fit Up
The interference fit between an outer ring and a housing will deform the outer ring inwards and the housing outward. When hoop stress is imparted, there are different stiffness values for each component. Consequently, they will deform differently as a function of the interference pressure. The total interference fit can be calculated by adding the outer ring and housing deflections together.
Shaft to Inner Ring Fit Up
The interference fit between an inner ring and a shaft will deform the shaft inward and the inner ring outward. This is similar to the outer ring to housing fit up but with an important difference. With shaft to inner ring fit up, internal bearing reactions generate an external pressure on the inner ring. Shaft deflection can be calculated as a function of the shaft geometry, material properties, and external pressure.
Get the System Integration of Thin Section Ball Bearings White Paper
Thin section bearings have applications ranging from robots and rotary indexing tables to textile machines, printing presses, and machine tools. They’re also used in X-ray scanners, helicopter rotors, and gun turrets. Although thin section bearings offer important advantages, they are more affected by the system around them than other bearings. To learn how to account for this, request this white paper from Schatz.
