Press mounting require a large force. When attaching the inner ring firmly to the shaft, the force to press-mount an inner ring in the axial direction varies depending on interference and shaft diameter. Moreover, during press mounting work, brinelling indentations may be caused on the raceway surfaces by rolling elements if force is applied to the outer ring. Thus, it is critical to know the fitting surface pressure on mounting performing.

● Pressure and maximum allowable stress
The press fitting force or withdrawal force of the fitted surface, and maximum allowable stress between fitting surfaces which are applied to a solid shaft or hollow shaft, can be expressed by the following equations.

Fit conditions		Equation	Codes (units: N {kgf}, mm)
Fitted surface pressure Mpa {kgf/mm2}	Solid steel shaft/inner ring fit		d: Shaft diameter, inner ring bore diameter d0: Hollow shaft inner diameter Di: Inner ring average groove diameter Δdeff: Effective interference E: Elasticity factor
	Hollow steel shaft/inner ring fit
	Steel housing/ outer ring fit		D: Housing inner diameter, bearing outer diameter D0: Outer ring average groove diameter Dh: Housing outer diameter ΔDeff: Effective interference
Maximun allowable stress	Shaft/inner ring fit		Inner ring bore diameter face maximum allowable stress
Mpa {kgf/mm2}	Housing/ outer ring fit		Outer ring inner diameter face maximum allowable stress

Average fit interference as it relates to surface pressure and max. allowable stress	Maximum fit interference as it relates to surface pressure and max. allowable stress

● Necessary press fit and pullout force
Excessive interference can sometimes produce abnormally large stress in the inner ring, which may cause the inner ring to crack or be otherwise damaged. Euquation below can be used to calculate the necessary pullout force for press fit for inner rings and shafts or outer rings and housings.

● Press fit and pullout sliding friction coefficient