Development of Loosening Tester for Small-size Threaded Fasteners

Screw loosening tests are often performed with a size of about M10. Ease of load application to screw fasteners and ease of measurement of axial force for detecting loosening are the main reasons. In comparison with that, in the loosening test of small diameter screws, since the sample of the test is small, it is difficult to detect the load applied to the screw fastener, addition of displacement, loosening, and the like. This study proposes a method of looseness test and a method of detecting looseness for a small diameter screw of about M1. In this study, we proposed a method to test for screw loosening using inertia. We also proposed a method to detect the occurrence of looseness during the test. Experiments were performed to confirm that they were effective.