Theoretical modelling of the self-tapping screw fastening process

The results of a theoretical study of the self-tapping screw insertion process are presented. Fundamental concepts of engineering mechanics are employed to analyse the axial torque required to complete a general self-tapping screw insertion operation. Equations for the screw insertion torque as a function of screw, hole and material properties are presented. Experimental results for torque signature signals are compared with the predictions of the theoretical model, confirming the validity of the model. The theoretical model provides a basis for developing automated monitoring and control strategies for self-tapping screw fastenings.