Conical rings are used to joint a shaft with other mechanical parts through frictional
forces induced by clamping of the inner ring into the outer one. In design, their coupling strength
and the allowable torque are determined with the well known analytical formulas. However, the
assumption of rigid and smooth contacts considered in the analytical solution generates technical
uncertainties for reliability of conical joints especially for their small dimensions. The coupling
strength of the conical rings is investigated at a set-up and by using Finite Element (FE) Method. A
FE model of the analytically analysed conical joint is created with friction contact conditions on all
interfaces of the joint. For a very fine mesh with the smooth interfaces, the FE contact forces differ
remarkably from the analytical solution. This confirms that the elasticity of parts has to be taken
into account in the design process. To assess an influence of real contact profiles on the coupling
performance, contours of contact surfaces are measured at a Mitutoyo coordinate measuring
machine. Based on the measured height variation in the normal to the contact plane, the surface
profiles are extrapolated by approximation functions. Then, the FE mesh is modified locally on the
contact with respect to the extrapolated profile functions and coupling strength of the conical joint
is computed with friction sliding. According to the obtained results, the implementation of the real
profile of the contact is needed in the design process to avoid failures under real operation
conditions of conical joints. According to the obtained FE static results, the contour irregularities
induces local separations in the contact, which can be monitored by measuring electrical resistance
between the outer and inner conical rings.