An experimental investigation of torque signature signals for self-tapping screws

The results of an experimental study on the self-tapping screw insertion process are presented. A test rig designed and constructed for measuring the torque signature signals during screw insertions is described. Experimental results for torque signature signals during general self-tapping screw fastenings are given graphically, confirming the five-stage variation with screw insertion depth predicted by an earlier theoretical study. The experimental data provide a basis for the further development of empirical and theoretical models of the self-tapping screw fastening process, in order to formulate and put into practice automated monitoring and control strategies.