A New Tightening Technique for Threaded Fasteners

A new technique for tightening threaded fasteners was proposed aiming to assure the quality and the reliability in the tightening operations. The technique is based on the torque difference and the relative rotation angle in tightening and loosening process, and no preliminary experiment is required. Repeated tightening (and loosening) experiments were performed for different types of lubricant to verify the applicability of this technique. Experimental results show that the preload provided to the joint can be estimated with high accuracy and precision by this technique, and the possibility to boost the reliability of tightening control is confirmed.