Experimental Study of the Effect of Conventional Manufacturing Geometric Deviation in the Fitted Cylindrical Joint on its Strength

Fit joints are widely used in industry to connect bush to shaft and its manufacturing process is always associated with geometric deviations similar to other processes. In a cylindrical fit connection, the geometrical deviation of the shaft and the bush is in order of one hundredth of millimeter, which is a common precision in manufacturing. This range of error seems to be significant compared to the required dimensional interference to make the connections and affects the strength of the interference fit joints. Usually, certain geometrical deviations will occur in the production process considering the selected manufacturing method. This research attempted to investigate the effect of common geometric deviations at the surface of interference of cylindrical interference fit on the experimental extraction strength. In this regard, 8 specimens of interference fit with same characteristic of dimensions, surface roughness and interference were produced. Furthermore, shafts with certain geometrical deviation (standard sample, two-lobes, three-lobes and conical) were made and fitted. Then, the extraction force of each part was extracted experimentally. Taking into consideration precise measurements of the parts dimension, the effect of shaft geometrical deviations on the strength of the joint was investigated. The results showed that the geometrical deviation affects the extraction strength. However, in the quality control process of these parts, by measuring the dimensions of the parts, the effects of these usual geometrical deviations on the joint strength could be predicted and the quality control process can be performed more effectively.