The re-tightening method is used in order to check whether the bolted joint was sufficiently tightened or not. However, characteristics of the re-tightening method were not sufficiently investigated. Therefore the behavior of retightening process of a bolted joint must be revealed. In this study, we have investigated behaviors of re-tightening torque in the re-tightening process of a bolted joint focusing on the lubricated condition. The experiments were performed using three lubricants, machine oil ISO VG46, MoS2 grease and a special lubricant for bolt tightening stabilization BTS, were used. The results showed that the re-tightening torque depends on the lubricant. Scatter band of the retightening torques for BTS was the smallest of all.
