The contact stress between the roller end face and the retaining edge can be calculated by the formula of contact stress and deformation introduced previously. The sub surface is usually flat, and there is an arc chamfer at the joint with the convex part of the roller shape. The flange can also be part of the plane. In cylindrical roller bearings, this is a common design. When it is required to bear the thrust load between the roller end face and the retaining edge, sometimes the retaining edge is designed as a cone. In this case, the chamfer of the roller will contact with the retaining edge, and the angle between the retaining edge and the radial plane is called the angle of the retaining edge. In addition, the roller end surface can also be designed as a spherical surface, so that the spherical end surface of the roller contacts with the inclined rib. This structure helps to improve lubrication, but reduces the guiding ability of the rib to the roller. In this case, the angle of the roller must be controlled by the cage. For the case of spherical end face roller and inclined flange, they can be simulated as the contact between sphere and cylinder. For the convenience of calculation, the radius of the sphere is equal to the radius of the spherical end face of the roller, while the radius of the cylinder can be approximated by the radius of curvature of the conical flange at the theoretical contact point. The contact stress and deformation can be calculated according to the known elastic contact load, material characteristics and contact geometric parameters of roller flange. This method can only be approximate, because the roller end face and rib do not satisfy the assumption of Hera half space. In addition, the radius of curvature of the tapered flange is not constant, but changes along the contact width. This method is only applicable to the contact between the complete spherical roller end face and the tapered flange. Improper geometry and excessive skewness may cause the contact ellipse to be cut off by the edge of flange, oil groove or roller chamfer, which is no longer suitable for Hertz theoretical model, and should be avoided in the design, otherwise it will cause high edge stress and make the lubrication worse. The contact between the flat face roller and the inclined edge is seldom attributed to the simple calculation of the contact stress, because the properties of the contact surface are difficult to be properly simulated at and near the junction of the chamfer and the flat face of the roller. For approximate calculation, the concept of effective roller radius can be adopted, which is an imaginary radius connecting the chamfer and the end face of the roller. If necessary, finite element stress analysis technology can be used to obtain more accurate contact stress distribution.