In this report are studied the influences of surface roughness on the contacting pres-sure, tightness of fits and ratio of contact.
Transfiguration of the surfaces under the repeating fits is analysed by introducing the idea of real ratio of contact which has been reported by Bowden and Holm, into the distribution of surface roughness, and thus the actural fitting pressure, which is as a rule, different from the theoretical value, becomes possible to be estimated. As the number of repeating fits increases and the tightness becomes lower, the peaks of the surface profiles are flattened, and the bearing surface draws near to the position a little apart from the center surface of the initial irregular profiles of the surface.
Hence the final tightness after repeating fits can be estimated if the initial diameters and the figures of surface irregularities are known.