Bearing Stiffness

Bearing stiffness is the resistance of a ball bearing assembly to deformation under an applied load or force. The stiffness of a ball bearing is a measure of how much it resists deformation against that load or force.  More specifically, stiffness is the ability of a bearing to maintain its shape while supporting a load. When a load is applied to a bearing, it causes the races and balls within the bearing to deform. The stiffness of the bearing determines how much (or how little) this deformation occurs. A stiffer bearing will deform less, leading to better support for the load and less loss of energy due to the friction generated within the altered geometry of the bearing assembly.

Stiffness is influenced by the material properties of the bearing components (such as the races and balls), the design of the bearing, and the preload applied during assembly. Proper preload ensures that the bearing components are in contact and distribute the load evenly, which helps maintain the proper stiffness.

In systems where precision is important, maintaining tight tolerances and minimizing deflection is vital to proper operation.  Examples of such systems are machine tools, robotics, and aerospace systems.  Proper stiffness contributes greatly to the overall accuracy, performance, and efficiency of the system.

A few things to note  (see graphs on this page showing stiffness vs. preload methodology and deflection vs applied load with these preload methods):

• The stiffness of a rolling element bearing is dependent on the bearing type, size, materials, as well clearance and or preload.
• Rolling element bearing stiffness is typically expressed as a spring rate (force versus deflection).
• It is important to understand that rolling element bearing deflection as a function of force is not linear.
• The bearing deflection as a function of force is also different in each axis of applied load.

Learn more about preloading with these other resources:

• Preloading Angular Contact Ball Bearings
• Principles of Preloading Angular Contact Ball Bearings