1. The calibration conditions — the calibration allowance and the taper angle of the penetrating parts of the calibrating elements, as well as the structure, porosity, and dimensions of the bearings — exert a definite influence on the degree of plastic deformation to which the surface layers are subjected, the magnitude of elastic lag, and the calibration force. On the basis of the experimental results, recommendations are given concerning the determination of calibration allowances and of the allowance for the effect of elastic lag on the working dimensions of calibration press-dies. 2. Investigations of the calibration process on massive specimens did not make it possible to obtain reliable data on the calibration process. The most complete data on the calibration process can be obtained in experiments on specimens with a cavity or on bushing-type bearings. 3. In comparison with two-stage calibration, the combined calibration method is more suitable for processing porous bearing billets. In using this method, the bearing's outside surface is compressed to a higher degree than the inside surface and, which is most important, the compression of the inside surface is effected only by the action of forces which are normal to the surface to be calibrated. In using the two-stage calibration method, the outside surface is insufficiently calibrated, while the inside surface may be excessively compressed. Therefore, when deciding upon the method for calibrating porous bearings, combined calibration should be preferred. 4. Combined calibration is especially effective if the dimensions of the sintered bearing billets are determined in advance by the dimensions of the die and the punch. Therefore, this article provides the equations necessary for determining the operating elements of press-dies.