Electric impact screwdrivers are widely used in the assembly process of fixed threaded joints. They have a number of advantages over hydraulic or pneumatic tools with similar performance - they have the ability to adjust the rotation frequency of the chuck, relatively light weight, as well as they are high-yielding. The main technical parameters of an electric impact screwdriver are: power; speed; maximum torque. Impact screwdrivers differ from conventional (impact-free) analogues with significantly higher achievable tightening torques at the lowest possible return to the tool body. This effect is achieved by the fact that the nut or screw head is not subjected to a constant tightening force, but to a series of powerful but sufficiently short impacts directed tangentially to the screw head. In the event that the tool switches from tightening mode to impact tightening mode, the rotational speed of the rotor head decreases rapidly, while the resulting torque increases, and the total value of this moment becomes equal to the sum of the individual moments of each impact. Taking into account the results of research, when assembling fixed threaded connections with a short impactor operating time, it is recommended to choose screws with minimal protrusion in relation to the nut (assembled position), thus reducing the screw length, which is also associated with power consumption before impactor operation. When assembling with a larger impactor operating time, the effect of screw length on total energy consumption is reduced.